nfs4proc.c

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/*
 *  fs/nfs/nfs4proc.c
 *
 *  Client-side procedure declarations for NFSv4.
 *
 *  Copyright (c) 2002 The Regents of the University of Michigan.
 *  All rights reserved.
 *
 *  Kendrick Smith <[email protected]>
 *  Andy Adamson   <[email protected]>
 *
 *  Redistribution and use in source and binary forms, with or without
 *  modification, are permitted provided that the following conditions
 *  are met:
 *
 *  1. Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 *  2. Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in the
 *     documentation and/or other materials provided with the distribution.
 *  3. Neither the name of the University nor the names of its
 *     contributors may be used to endorse or promote products derived
 *     from this software without specific prior written permission.
 *
 *  THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED
 *  WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
 *  MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 *  DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 *  FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 *  CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 *  SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
 *  BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 *  LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 *  NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 *  SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include <linux/mm.h>
#include <linux/delay.h>
#include <linux/errno.h>
#include <linux/string.h>
#include <linux/ratelimit.h>
#include <linux/printk.h>
#include <linux/slab.h>
#include <linux/sunrpc/clnt.h>
#include <linux/nfs.h>
#include <linux/nfs4.h>
#include <linux/nfs_fs.h>
#include <linux/nfs_page.h>
#include <linux/nfs_mount.h>
#include <linux/namei.h>
#include <linux/mount.h>
#include <linux/module.h>
#include <linux/nfs_idmap.h>
#include <linux/sunrpc/bc_xprt.h>
#include <linux/xattr.h>
#include <linux/utsname.h>
#include <linux/freezer.h>

#include "nfs4_fs.h"
#include "delegation.h"
#include "internal.h"
#include "iostat.h"
#include "callback.h"
#include "pnfs.h"
#include "netns.h"

#define NFSDBG_FACILITY     NFSDBG_PROC

#define NFS4_POLL_RETRY_MIN (HZ/10)
#define NFS4_POLL_RETRY_MAX (15*HZ)

#define NFS4_MAX_LOOP_ON_RECOVER (10)

struct nfs4_opendata;
static int _nfs4_proc_open(struct nfs4_opendata *data);
static int _nfs4_recover_proc_open(struct nfs4_opendata *data);
static int nfs4_do_fsinfo(struct nfs_server *, struct nfs_fh *, struct nfs_fsinfo *);
static int nfs4_async_handle_error(struct rpc_task *, const struct nfs_server *, struct nfs4_state *);
static void nfs_fixup_referral_attributes(struct nfs_fattr *fattr);
static int nfs4_proc_getattr(struct nfs_server *, struct nfs_fh *, struct nfs_fattr *);
static int _nfs4_proc_getattr(struct nfs_server *server, struct nfs_fh *fhandle, struct nfs_fattr *fattr);
static int nfs4_do_setattr(struct inode *inode, struct rpc_cred *cred,
                struct nfs_fattr *fattr, struct iattr *sattr,
                struct nfs4_state *state);
#ifdef CONFIG_NFS_V4_1
static int nfs41_test_stateid(struct nfs_server *, nfs4_stateid *);
static int nfs41_free_stateid(struct nfs_server *, nfs4_stateid *);
#endif
/* Prevent leaks of NFSv4 errors into userland */
static int nfs4_map_errors(int err)
{
    if (err >= -1000)
        return err;
    switch (err) {
    case -NFS4ERR_RESOURCE:
        return -EREMOTEIO;
    case -NFS4ERR_WRONGSEC:
        return -EPERM;
    case -NFS4ERR_BADOWNER:
    case -NFS4ERR_BADNAME:
        return -EINVAL;
    case -NFS4ERR_SHARE_DENIED:
        return -EACCES;
    case -NFS4ERR_MINOR_VERS_MISMATCH:
        return -EPROTONOSUPPORT;
    case -NFS4ERR_ACCESS:
        return -EACCES;
    default:
        dprintk("%s could not handle NFSv4 error %d\n",
                __func__, -err);
        break;
    }
    return -EIO;
}

/*
 * This is our standard bitmap for GETATTR requests.
 */
const u32 nfs4_fattr_bitmap[3] = {
    FATTR4_WORD0_TYPE
    | FATTR4_WORD0_CHANGE
    | FATTR4_WORD0_SIZE
    | FATTR4_WORD0_FSID
    | FATTR4_WORD0_FILEID,
    FATTR4_WORD1_MODE
    | FATTR4_WORD1_NUMLINKS
    | FATTR4_WORD1_OWNER
    | FATTR4_WORD1_OWNER_GROUP
    | FATTR4_WORD1_RAWDEV
    | FATTR4_WORD1_SPACE_USED
    | FATTR4_WORD1_TIME_ACCESS
    | FATTR4_WORD1_TIME_METADATA
    | FATTR4_WORD1_TIME_MODIFY
};

static const u32 nfs4_pnfs_open_bitmap[3] = {
    FATTR4_WORD0_TYPE
    | FATTR4_WORD0_CHANGE
    | FATTR4_WORD0_SIZE
    | FATTR4_WORD0_FSID
    | FATTR4_WORD0_FILEID,
    FATTR4_WORD1_MODE
    | FATTR4_WORD1_NUMLINKS
    | FATTR4_WORD1_OWNER
    | FATTR4_WORD1_OWNER_GROUP
    | FATTR4_WORD1_RAWDEV
    | FATTR4_WORD1_SPACE_USED
    | FATTR4_WORD1_TIME_ACCESS
    | FATTR4_WORD1_TIME_METADATA
    | FATTR4_WORD1_TIME_MODIFY,
    FATTR4_WORD2_MDSTHRESHOLD
};

static const u32 nfs4_open_noattr_bitmap[3] = {
    FATTR4_WORD0_TYPE
    | FATTR4_WORD0_CHANGE
    | FATTR4_WORD0_FILEID,
};

const u32 nfs4_statfs_bitmap[2] = {
    FATTR4_WORD0_FILES_AVAIL
    | FATTR4_WORD0_FILES_FREE
    | FATTR4_WORD0_FILES_TOTAL,
    FATTR4_WORD1_SPACE_AVAIL
    | FATTR4_WORD1_SPACE_FREE
    | FATTR4_WORD1_SPACE_TOTAL
};

const u32 nfs4_pathconf_bitmap[2] = {
    FATTR4_WORD0_MAXLINK
    | FATTR4_WORD0_MAXNAME,
    0
};

const u32 nfs4_fsinfo_bitmap[3] = { FATTR4_WORD0_MAXFILESIZE
            | FATTR4_WORD0_MAXREAD
            | FATTR4_WORD0_MAXWRITE
            | FATTR4_WORD0_LEASE_TIME,
            FATTR4_WORD1_TIME_DELTA
            | FATTR4_WORD1_FS_LAYOUT_TYPES,
            FATTR4_WORD2_LAYOUT_BLKSIZE
};

const u32 nfs4_fs_locations_bitmap[2] = {
    FATTR4_WORD0_TYPE
    | FATTR4_WORD0_CHANGE
    | FATTR4_WORD0_SIZE
    | FATTR4_WORD0_FSID
    | FATTR4_WORD0_FILEID
    | FATTR4_WORD0_FS_LOCATIONS,
    FATTR4_WORD1_MODE
    | FATTR4_WORD1_NUMLINKS
    | FATTR4_WORD1_OWNER
    | FATTR4_WORD1_OWNER_GROUP
    | FATTR4_WORD1_RAWDEV
    | FATTR4_WORD1_SPACE_USED
    | FATTR4_WORD1_TIME_ACCESS
    | FATTR4_WORD1_TIME_METADATA
    | FATTR4_WORD1_TIME_MODIFY
    | FATTR4_WORD1_MOUNTED_ON_FILEID
};

static void nfs4_setup_readdir(u64 cookie, __be32 *verifier, struct dentry *dentry,
        struct nfs4_readdir_arg *readdir)
{
    __be32 *start, *p;

    BUG_ON(readdir->count < 80);
    if (cookie > 2) {
        readdir->cookie = cookie;
        memcpy(&readdir->verifier, verifier, sizeof(readdir->verifier));
        return;
    }

    readdir->cookie = 0;
    memset(&readdir->verifier, 0, sizeof(readdir->verifier));
    if (cookie == 2)
        return;
    
    /*
     * NFSv4 servers do not return entries for '.' and '..'
     * Therefore, we fake these entries here.  We let '.'
     * have cookie 0 and '..' have cookie 1.  Note that
     * when talking to the server, we always send cookie 0
     * instead of 1 or 2.
     */
    start = p = kmap_atomic(*readdir->pages);
    
    if (cookie == 0) {
        *p++ = xdr_one;                                  /* next */
        *p++ = xdr_zero;                   /* cookie, first word */
        *p++ = xdr_one;                   /* cookie, second word */
        *p++ = xdr_one;                             /* entry len */
        memcpy(p, ".\0\0\0", 4);                        /* entry */
        p++;
        *p++ = xdr_one;                         /* bitmap length */
        *p++ = htonl(FATTR4_WORD0_FILEID);             /* bitmap */
        *p++ = htonl(8);              /* attribute buffer length */
        p = xdr_encode_hyper(p, NFS_FILEID(dentry->d_inode));
    }
    
    *p++ = xdr_one;                                  /* next */
    *p++ = xdr_zero;                   /* cookie, first word */
    *p++ = xdr_two;                   /* cookie, second word */
    *p++ = xdr_two;                             /* entry len */
    memcpy(p, "..\0\0", 4);                         /* entry */
    p++;
    *p++ = xdr_one;                         /* bitmap length */
    *p++ = htonl(FATTR4_WORD0_FILEID);             /* bitmap */
    *p++ = htonl(8);              /* attribute buffer length */
    p = xdr_encode_hyper(p, NFS_FILEID(dentry->d_parent->d_inode));

    readdir->pgbase = (char *)p - (char *)start;
    readdir->count -= readdir->pgbase;
    kunmap_atomic(start);
}

static int nfs4_wait_clnt_recover(struct nfs_client *clp)
{
    int res;

    might_sleep();

    res = wait_on_bit(&clp->cl_state, NFS4CLNT_MANAGER_RUNNING,
            nfs_wait_bit_killable, TASK_KILLABLE);
    if (res)
        return res;

    if (clp->cl_cons_state < 0)
        return clp->cl_cons_state;
    return 0;
}

static int nfs4_delay(struct rpc_clnt *clnt, long *timeout)
{
    int res = 0;

    might_sleep();

    if (*timeout <= 0)
        *timeout = NFS4_POLL_RETRY_MIN;
    if (*timeout > NFS4_POLL_RETRY_MAX)
        *timeout = NFS4_POLL_RETRY_MAX;
    freezable_schedule_timeout_killable(*timeout);
    if (fatal_signal_pending(current))
        res = -ERESTARTSYS;
    *timeout <<= 1;
    return res;
}

/* This is the error handling routine for processes that are allowed
 * to sleep.
 */
static int nfs4_handle_exception(struct nfs_server *server, int errorcode, struct nfs4_exception *exception)
{
    struct nfs_client *clp = server->nfs_client;
    struct nfs4_state *state = exception->state;
    struct inode *inode = exception->inode;
    int ret = errorcode;

    exception->retry = 0;
    switch(errorcode) {
        case 0:
            return 0;
        case -NFS4ERR_OPENMODE:
            if (inode && nfs4_have_delegation(inode, FMODE_READ)) {
                nfs4_inode_return_delegation(inode);
                exception->retry = 1;
                return 0;
            }
            if (state == NULL)
                break;
            nfs4_schedule_stateid_recovery(server, state);
            goto wait_on_recovery;
        case -NFS4ERR_DELEG_REVOKED:
        case -NFS4ERR_ADMIN_REVOKED:
        case -NFS4ERR_BAD_STATEID:
            if (state == NULL)
                break;
            nfs_remove_bad_delegation(state->inode);
            nfs4_schedule_stateid_recovery(server, state);
            goto wait_on_recovery;
        case -NFS4ERR_EXPIRED:
            if (state != NULL)
                nfs4_schedule_stateid_recovery(server, state);
        case -NFS4ERR_STALE_STATEID:
        case -NFS4ERR_STALE_CLIENTID:
            nfs4_schedule_lease_recovery(clp);
            goto wait_on_recovery;
#if defined(CONFIG_NFS_V4_1)
        case -NFS4ERR_BADSESSION:
        case -NFS4ERR_BADSLOT:
        case -NFS4ERR_BAD_HIGH_SLOT:
        case -NFS4ERR_CONN_NOT_BOUND_TO_SESSION:
        case -NFS4ERR_DEADSESSION:
        case -NFS4ERR_SEQ_FALSE_RETRY:
        case -NFS4ERR_SEQ_MISORDERED:
            dprintk("%s ERROR: %d Reset session\n", __func__,
                errorcode);
            nfs4_schedule_session_recovery(clp->cl_session, errorcode);
            goto wait_on_recovery;
#endif /* defined(CONFIG_NFS_V4_1) */
        case -NFS4ERR_FILE_OPEN:
            if (exception->timeout > HZ) {
                /* We have retried a decent amount, time to
                 * fail
                 */
                ret = -EBUSY;
                break;
            }
        case -NFS4ERR_GRACE:
        case -NFS4ERR_DELAY:
        case -EKEYEXPIRED:
            ret = nfs4_delay(server->client, &exception->timeout);
            if (ret != 0)
                break;
        case -NFS4ERR_RETRY_UNCACHED_REP:
        case -NFS4ERR_OLD_STATEID:
            exception->retry = 1;
            break;
        case -NFS4ERR_BADOWNER:
            /* The following works around a Linux server bug! */
        case -NFS4ERR_BADNAME:
            if (server->caps & NFS_CAP_UIDGID_NOMAP) {
                server->caps &= ~NFS_CAP_UIDGID_NOMAP;
                exception->retry = 1;
                printk(KERN_WARNING "NFS: v4 server %s "
                        "does not accept raw "
                        "uid/gids. "
                        "Reenabling the idmapper.\n",
                        server->nfs_client->cl_hostname);
            }
    }
    /* We failed to handle the error */
    return nfs4_map_errors(ret);
wait_on_recovery:
    ret = nfs4_wait_clnt_recover(clp);
    if (ret == 0)
        exception->retry = 1;
    return ret;
}


static void do_renew_lease(struct nfs_client *clp, unsigned long timestamp)
{
    spin_lock(&clp->cl_lock);
    if (time_before(clp->cl_last_renewal,timestamp))
        clp->cl_last_renewal = timestamp;
    spin_unlock(&clp->cl_lock);
}

static void renew_lease(const struct nfs_server *server, unsigned long timestamp)
{
    do_renew_lease(server->nfs_client, timestamp);
}

#if defined(CONFIG_NFS_V4_1)

/*
 * nfs4_free_slot - free a slot and efficiently update slot table.
 *
 * freeing a slot is trivially done by clearing its respective bit
 * in the bitmap.
 * If the freed slotid equals highest_used_slotid we want to update it
 * so that the server would be able to size down the slot table if needed,
 * otherwise we know that the highest_used_slotid is still in use.
 * When updating highest_used_slotid there may be "holes" in the bitmap
 * so we need to scan down from highest_used_slotid to 0 looking for the now
 * highest slotid in use.
 * If none found, highest_used_slotid is set to NFS4_NO_SLOT.
 *
 * Must be called while holding tbl->slot_tbl_lock
 */
static void
nfs4_free_slot(struct nfs4_slot_table *tbl, u32 slotid)
{
    BUG_ON(slotid >= NFS4_MAX_SLOT_TABLE);
    /* clear used bit in bitmap */
    __clear_bit(slotid, tbl->used_slots);

    /* update highest_used_slotid when it is freed */
    if (slotid == tbl->highest_used_slotid) {
        slotid = find_last_bit(tbl->used_slots, tbl->max_slots);
        if (slotid < tbl->max_slots)
            tbl->highest_used_slotid = slotid;
        else
            tbl->highest_used_slotid = NFS4_NO_SLOT;
    }
    dprintk("%s: slotid %u highest_used_slotid %d\n", __func__,
        slotid, tbl->highest_used_slotid);
}

bool nfs4_set_task_privileged(struct rpc_task *task, void *dummy)
{
    rpc_task_set_priority(task, RPC_PRIORITY_PRIVILEGED);
    return true;
}

/*
 * Signal state manager thread if session fore channel is drained
 */
static void nfs4_check_drain_fc_complete(struct nfs4_session *ses)
{
    if (!test_bit(NFS4_SESSION_DRAINING, &ses->session_state)) {
        rpc_wake_up_first(&ses->fc_slot_table.slot_tbl_waitq,
                nfs4_set_task_privileged, NULL);
        return;
    }

    if (ses->fc_slot_table.highest_used_slotid != NFS4_NO_SLOT)
        return;

    dprintk("%s COMPLETE: Session Fore Channel Drained\n", __func__);
    complete(&ses->fc_slot_table.complete);
}

/*
 * Signal state manager thread if session back channel is drained
 */
void nfs4_check_drain_bc_complete(struct nfs4_session *ses)
{
    if (!test_bit(NFS4_SESSION_DRAINING, &ses->session_state) ||
        ses->bc_slot_table.highest_used_slotid != NFS4_NO_SLOT)
        return;
    dprintk("%s COMPLETE: Session Back Channel Drained\n", __func__);
    complete(&ses->bc_slot_table.complete);
}

static void nfs41_sequence_free_slot(struct nfs4_sequence_res *res)
{
    struct nfs4_slot_table *tbl;

    tbl = &res->sr_session->fc_slot_table;
    if (!res->sr_slot) {
        /* just wake up the next guy waiting since
         * we may have not consumed a slot after all */
        dprintk("%s: No slot\n", __func__);
        return;
    }

    spin_lock(&tbl->slot_tbl_lock);
    nfs4_free_slot(tbl, res->sr_slot - tbl->slots);
    nfs4_check_drain_fc_complete(res->sr_session);
    spin_unlock(&tbl->slot_tbl_lock);
    res->sr_slot = NULL;
}

static int nfs41_sequence_done(struct rpc_task *task, struct nfs4_sequence_res *res)
{
    unsigned long timestamp;
    struct nfs_client *clp;

    /*
     * sr_status remains 1 if an RPC level error occurred. The server
     * may or may not have processed the sequence operation..
     * Proceed as if the server received and processed the sequence
     * operation.
     */
    if (res->sr_status == 1)
        res->sr_status = NFS_OK;

    /* don't increment the sequence number if the task wasn't sent */
    if (!RPC_WAS_SENT(task))
        goto out;

    /* Check the SEQUENCE operation status */
    switch (res->sr_status) {
    case 0:
        /* Update the slot's sequence and clientid lease timer */
        ++res->sr_slot->seq_nr;
        timestamp = res->sr_renewal_time;
        clp = res->sr_session->clp;
        do_renew_lease(clp, timestamp);
        /* Check sequence flags */
        if (res->sr_status_flags != 0)
            nfs4_schedule_lease_recovery(clp);
        break;
    case -NFS4ERR_DELAY:
        /* The server detected a resend of the RPC call and
         * returned NFS4ERR_DELAY as per Section 2.10.6.2
         * of RFC5661.
         */
        dprintk("%s: slot=%td seq=%d: Operation in progress\n",
            __func__,
            res->sr_slot - res->sr_session->fc_slot_table.slots,
            res->sr_slot->seq_nr);
        goto out_retry;
    default:
        /* Just update the slot sequence no. */
        ++res->sr_slot->seq_nr;
    }
out:
    /* The session may be reset by one of the error handlers. */
    dprintk("%s: Error %d free the slot \n", __func__, res->sr_status);
    nfs41_sequence_free_slot(res);
    return 1;
out_retry:
    if (!rpc_restart_call(task))
        goto out;
    rpc_delay(task, NFS4_POLL_RETRY_MAX);
    return 0;
}

static int nfs4_sequence_done(struct rpc_task *task,
                   struct nfs4_sequence_res *res)
{
    if (res->sr_session == NULL)
        return 1;
    return nfs41_sequence_done(task, res);
}

/*
 * nfs4_find_slot - efficiently look for a free slot
 *
 * nfs4_find_slot looks for an unset bit in the used_slots bitmap.
 * If found, we mark the slot as used, update the highest_used_slotid,
 * and respectively set up the sequence operation args.
 * The slot number is returned if found, or NFS4_NO_SLOT otherwise.
 *
 * Note: must be called with under the slot_tbl_lock.
 */
static u32
nfs4_find_slot(struct nfs4_slot_table *tbl)
{
    u32 slotid;
    u32 ret_id = NFS4_NO_SLOT;

    dprintk("--> %s used_slots=%04lx highest_used=%u max_slots=%u\n",
        __func__, tbl->used_slots[0], tbl->highest_used_slotid,
        tbl->max_slots);
    slotid = find_first_zero_bit(tbl->used_slots, tbl->max_slots);
    if (slotid >= tbl->max_slots)
        goto out;
    __set_bit(slotid, tbl->used_slots);
    if (slotid > tbl->highest_used_slotid ||
            tbl->highest_used_slotid == NFS4_NO_SLOT)
        tbl->highest_used_slotid = slotid;
    ret_id = slotid;
out:
    dprintk("<-- %s used_slots=%04lx highest_used=%d slotid=%d \n",
        __func__, tbl->used_slots[0], tbl->highest_used_slotid, ret_id);
    return ret_id;
}

static void nfs41_init_sequence(struct nfs4_sequence_args *args,
        struct nfs4_sequence_res *res, int cache_reply)
{
    args->sa_session = NULL;
    args->sa_cache_this = 0;
    if (cache_reply)
        args->sa_cache_this = 1;
    res->sr_session = NULL;
    res->sr_slot = NULL;
}

int nfs41_setup_sequence(struct nfs4_session *session,
                struct nfs4_sequence_args *args,
                struct nfs4_sequence_res *res,
                struct rpc_task *task)
{
    struct nfs4_slot *slot;
    struct nfs4_slot_table *tbl;
    u32 slotid;

    dprintk("--> %s\n", __func__);
    /* slot already allocated? */
    if (res->sr_slot != NULL)
        return 0;

    tbl = &session->fc_slot_table;

    spin_lock(&tbl->slot_tbl_lock);
    if (test_bit(NFS4_SESSION_DRAINING, &session->session_state) &&
        !rpc_task_has_priority(task, RPC_PRIORITY_PRIVILEGED)) {
        /* The state manager will wait until the slot table is empty */
        rpc_sleep_on(&tbl->slot_tbl_waitq, task, NULL);
        spin_unlock(&tbl->slot_tbl_lock);
        dprintk("%s session is draining\n", __func__);
        return -EAGAIN;
    }

    if (!rpc_queue_empty(&tbl->slot_tbl_waitq) &&
        !rpc_task_has_priority(task, RPC_PRIORITY_PRIVILEGED)) {
        rpc_sleep_on(&tbl->slot_tbl_waitq, task, NULL);
        spin_unlock(&tbl->slot_tbl_lock);
        dprintk("%s enforce FIFO order\n", __func__);
        return -EAGAIN;
    }

    slotid = nfs4_find_slot(tbl);
    if (slotid == NFS4_NO_SLOT) {
        rpc_sleep_on(&tbl->slot_tbl_waitq, task, NULL);
        spin_unlock(&tbl->slot_tbl_lock);
        dprintk("<-- %s: no free slots\n", __func__);
        return -EAGAIN;
    }
    spin_unlock(&tbl->slot_tbl_lock);

    rpc_task_set_priority(task, RPC_PRIORITY_NORMAL);
    slot = tbl->slots + slotid;
    args->sa_session = session;
    args->sa_slotid = slotid;

    dprintk("<-- %s slotid=%d seqid=%d\n", __func__, slotid, slot->seq_nr);

    res->sr_session = session;
    res->sr_slot = slot;
    res->sr_renewal_time = jiffies;
    res->sr_status_flags = 0;
    /*
     * sr_status is only set in decode_sequence, and so will remain
     * set to 1 if an rpc level failure occurs.
     */
    res->sr_status = 1;
    return 0;
}
EXPORT_SYMBOL_GPL(nfs41_setup_sequence);

int nfs4_setup_sequence(const struct nfs_server *server,
            struct nfs4_sequence_args *args,
            struct nfs4_sequence_res *res,
            struct rpc_task *task)
{
    struct nfs4_session *session = nfs4_get_session(server);
    int ret = 0;

    if (session == NULL)
        goto out;

    dprintk("--> %s clp %p session %p sr_slot %td\n",
        __func__, session->clp, session, res->sr_slot ?
            res->sr_slot - session->fc_slot_table.slots : -1);

    ret = nfs41_setup_sequence(session, args, res, task);
out:
    dprintk("<-- %s status=%d\n", __func__, ret);
    return ret;
}

struct nfs41_call_sync_data {
    const struct nfs_server *seq_server;
    struct nfs4_sequence_args *seq_args;
    struct nfs4_sequence_res *seq_res;
};

static void nfs41_call_sync_prepare(struct rpc_task *task, void *calldata)
{
    struct nfs41_call_sync_data *data = calldata;

    dprintk("--> %s data->seq_server %p\n", __func__, data->seq_server);

    if (nfs4_setup_sequence(data->seq_server, data->seq_args,
                data->seq_res, task))
        return;
    rpc_call_start(task);
}

static void nfs41_call_priv_sync_prepare(struct rpc_task *task, void *calldata)
{
    rpc_task_set_priority(task, RPC_PRIORITY_PRIVILEGED);
    nfs41_call_sync_prepare(task, calldata);
}

static void nfs41_call_sync_done(struct rpc_task *task, void *calldata)
{
    struct nfs41_call_sync_data *data = calldata;

    nfs41_sequence_done(task, data->seq_res);
}

static const struct rpc_call_ops nfs41_call_sync_ops = {
    .rpc_call_prepare = nfs41_call_sync_prepare,
    .rpc_call_done = nfs41_call_sync_done,
};

static const struct rpc_call_ops nfs41_call_priv_sync_ops = {
    .rpc_call_prepare = nfs41_call_priv_sync_prepare,
    .rpc_call_done = nfs41_call_sync_done,
};

static int nfs4_call_sync_sequence(struct rpc_clnt *clnt,
                   struct nfs_server *server,
                   struct rpc_message *msg,
                   struct nfs4_sequence_args *args,
                   struct nfs4_sequence_res *res,
                   int privileged)
{
    int ret;
    struct rpc_task *task;
    struct nfs41_call_sync_data data = {
        .seq_server = server,
        .seq_args = args,
        .seq_res = res,
    };
    struct rpc_task_setup task_setup = {
        .rpc_client = clnt,
        .rpc_message = msg,
        .callback_ops = &nfs41_call_sync_ops,
        .callback_data = &data
    };

    if (privileged)
        task_setup.callback_ops = &nfs41_call_priv_sync_ops;
    task = rpc_run_task(&task_setup);
    if (IS_ERR(task))
        ret = PTR_ERR(task);
    else {
        ret = task->tk_status;
        rpc_put_task(task);
    }
    return ret;
}

int _nfs4_call_sync_session(struct rpc_clnt *clnt,
                struct nfs_server *server,
                struct rpc_message *msg,
                struct nfs4_sequence_args *args,
                struct nfs4_sequence_res *res,
                int cache_reply)
{
    nfs41_init_sequence(args, res, cache_reply);
    return nfs4_call_sync_sequence(clnt, server, msg, args, res, 0);
}

#else
static inline
void nfs41_init_sequence(struct nfs4_sequence_args *args,
        struct nfs4_sequence_res *res, int cache_reply)
{
}

static int nfs4_sequence_done(struct rpc_task *task,
                   struct nfs4_sequence_res *res)
{
    return 1;
}
#endif /* CONFIG_NFS_V4_1 */

int _nfs4_call_sync(struct rpc_clnt *clnt,
            struct nfs_server *server,
            struct rpc_message *msg,
            struct nfs4_sequence_args *args,
            struct nfs4_sequence_res *res,
            int cache_reply)
{
    nfs41_init_sequence(args, res, cache_reply);
    return rpc_call_sync(clnt, msg, 0);
}

static inline
int nfs4_call_sync(struct rpc_clnt *clnt,
           struct nfs_server *server,
           struct rpc_message *msg,
           struct nfs4_sequence_args *args,
           struct nfs4_sequence_res *res,
           int cache_reply)
{
    return server->nfs_client->cl_mvops->call_sync(clnt, server, msg,
                        args, res, cache_reply);
}

static void update_changeattr(struct inode *dir, struct nfs4_change_info *cinfo)
{
    struct nfs_inode *nfsi = NFS_I(dir);

    spin_lock(&dir->i_lock);
    nfsi->cache_validity |= NFS_INO_INVALID_ATTR|NFS_INO_INVALID_DATA;
    if (!cinfo->atomic || cinfo->before != dir->i_version)
        nfs_force_lookup_revalidate(dir);
    dir->i_version = cinfo->after;
    spin_unlock(&dir->i_lock);
}

struct nfs4_opendata {
    struct kref kref;
    struct nfs_openargs o_arg;
    struct nfs_openres o_res;
    struct nfs_open_confirmargs c_arg;
    struct nfs_open_confirmres c_res;
    struct nfs4_string owner_name;
    struct nfs4_string group_name;
    struct nfs_fattr f_attr;
    struct dentry *dir;
    struct dentry *dentry;
    struct nfs4_state_owner *owner;
    struct nfs4_state *state;
    struct iattr attrs;
    unsigned long timestamp;
    unsigned int rpc_done : 1;
    int rpc_status;
    int cancelled;
};


static void nfs4_init_opendata_res(struct nfs4_opendata *p)
{
    p->o_res.f_attr = &p->f_attr;
    p->o_res.seqid = p->o_arg.seqid;
    p->c_res.seqid = p->c_arg.seqid;
    p->o_res.server = p->o_arg.server;
    p->o_res.access_request = p->o_arg.access;
    nfs_fattr_init(&p->f_attr);
    nfs_fattr_init_names(&p->f_attr, &p->owner_name, &p->group_name);
}

static struct nfs4_opendata *nfs4_opendata_alloc(struct dentry *dentry,
        struct nfs4_state_owner *sp, fmode_t fmode, int flags,
        const struct iattr *attrs,
        gfp_t gfp_mask)
{
    struct dentry *parent = dget_parent(dentry);
    struct inode *dir = parent->d_inode;
    struct nfs_server *server = NFS_SERVER(dir);
    struct nfs4_opendata *p;

    p = kzalloc(sizeof(*p), gfp_mask);
    if (p == NULL)
        goto err;
    p->o_arg.seqid = nfs_alloc_seqid(&sp->so_seqid, gfp_mask);
    if (p->o_arg.seqid == NULL)
        goto err_free;
    nfs_sb_active(dentry->d_sb);
    p->dentry = dget(dentry);
    p->dir = parent;
    p->owner = sp;
    atomic_inc(&sp->so_count);
    p->o_arg.fh = NFS_FH(dir);
    p->o_arg.open_flags = flags;
    p->o_arg.fmode = fmode & (FMODE_READ|FMODE_WRITE);
    /* don't put an ACCESS op in OPEN compound if O_EXCL, because ACCESS
     * will return permission denied for all bits until close */
    if (!(flags & O_EXCL)) {
        /* ask server to check for all possible rights as results
         * are cached */
        p->o_arg.access = NFS4_ACCESS_READ | NFS4_ACCESS_MODIFY |
                  NFS4_ACCESS_EXTEND | NFS4_ACCESS_EXECUTE;
    }
    p->o_arg.clientid = server->nfs_client->cl_clientid;
    p->o_arg.id.create_time = ktime_to_ns(sp->so_seqid.create_time);
    p->o_arg.id.uniquifier = sp->so_seqid.owner_id;
    p->o_arg.name = &dentry->d_name;
    p->o_arg.server = server;
    p->o_arg.bitmask = server->attr_bitmask;
    p->o_arg.open_bitmap = &nfs4_fattr_bitmap[0];
    p->o_arg.claim = NFS4_OPEN_CLAIM_NULL;
    if (attrs != NULL && attrs->ia_valid != 0) {
        __be32 verf[2];

        p->o_arg.u.attrs = &p->attrs;
        memcpy(&p->attrs, attrs, sizeof(p->attrs));

        verf[0] = jiffies;
        verf[1] = current->pid;
        memcpy(p->o_arg.u.verifier.data, verf,
                sizeof(p->o_arg.u.verifier.data));
    }
    p->c_arg.fh = &p->o_res.fh;
    p->c_arg.stateid = &p->o_res.stateid;
    p->c_arg.seqid = p->o_arg.seqid;
    nfs4_init_opendata_res(p);
    kref_init(&p->kref);
    return p;
err_free:
    kfree(p);
err:
    dput(parent);
    return NULL;
}

static void nfs4_opendata_free(struct kref *kref)
{
    struct nfs4_opendata *p = container_of(kref,
            struct nfs4_opendata, kref);
    struct super_block *sb = p->dentry->d_sb;

    nfs_free_seqid(p->o_arg.seqid);
    if (p->state != NULL)
        nfs4_put_open_state(p->state);
    nfs4_put_state_owner(p->owner);
    dput(p->dir);
    dput(p->dentry);
    nfs_sb_deactive(sb);
    nfs_fattr_free_names(&p->f_attr);
    kfree(p);
}

static void nfs4_opendata_put(struct nfs4_opendata *p)
{
    if (p != NULL)
        kref_put(&p->kref, nfs4_opendata_free);
}

static int nfs4_wait_for_completion_rpc_task(struct rpc_task *task)
{
    int ret;

    ret = rpc_wait_for_completion_task(task);
    return ret;
}

static int can_open_cached(struct nfs4_state *state, fmode_t mode, int open_mode)
{
    int ret = 0;

    if (open_mode & (O_EXCL|O_TRUNC))
        goto out;
    switch (mode & (FMODE_READ|FMODE_WRITE)) {
        case FMODE_READ:
            ret |= test_bit(NFS_O_RDONLY_STATE, &state->flags) != 0
                && state->n_rdonly != 0;
            break;
        case FMODE_WRITE:
            ret |= test_bit(NFS_O_WRONLY_STATE, &state->flags) != 0
                && state->n_wronly != 0;
            break;
        case FMODE_READ|FMODE_WRITE:
            ret |= test_bit(NFS_O_RDWR_STATE, &state->flags) != 0
                && state->n_rdwr != 0;
    }
out:
    return ret;
}

static int can_open_delegated(struct nfs_delegation *delegation, fmode_t fmode)
{
    if (delegation == NULL)
        return 0;
    if ((delegation->type & fmode) != fmode)
        return 0;
    if (test_bit(NFS_DELEGATION_NEED_RECLAIM, &delegation->flags))
        return 0;
    nfs_mark_delegation_referenced(delegation);
    return 1;
}

static void update_open_stateflags(struct nfs4_state *state, fmode_t fmode)
{
    switch (fmode) {
        case FMODE_WRITE:
            state->n_wronly++;
            break;
        case FMODE_READ:
            state->n_rdonly++;
            break;
        case FMODE_READ|FMODE_WRITE:
            state->n_rdwr++;
    }
    nfs4_state_set_mode_locked(state, state->state | fmode);
}

static void nfs_set_open_stateid_locked(struct nfs4_state *state, nfs4_stateid *stateid, fmode_t fmode)
{
    if (test_bit(NFS_DELEGATED_STATE, &state->flags) == 0)
        nfs4_stateid_copy(&state->stateid, stateid);
    nfs4_stateid_copy(&state->open_stateid, stateid);
    switch (fmode) {
        case FMODE_READ:
            set_bit(NFS_O_RDONLY_STATE, &state->flags);
            break;
        case FMODE_WRITE:
            set_bit(NFS_O_WRONLY_STATE, &state->flags);
            break;
        case FMODE_READ|FMODE_WRITE:
            set_bit(NFS_O_RDWR_STATE, &state->flags);
    }
}

static void nfs_set_open_stateid(struct nfs4_state *state, nfs4_stateid *stateid, fmode_t fmode)
{
    write_seqlock(&state->seqlock);
    nfs_set_open_stateid_locked(state, stateid, fmode);
    write_sequnlock(&state->seqlock);
}

static void __update_open_stateid(struct nfs4_state *state, nfs4_stateid *open_stateid, const nfs4_stateid *deleg_stateid, fmode_t fmode)
{
    /*
     * Protect the call to nfs4_state_set_mode_locked and
     * serialise the stateid update
     */
    write_seqlock(&state->seqlock);
    if (deleg_stateid != NULL) {
        nfs4_stateid_copy(&state->stateid, deleg_stateid);
        set_bit(NFS_DELEGATED_STATE, &state->flags);
    }
    if (open_stateid != NULL)
        nfs_set_open_stateid_locked(state, open_stateid, fmode);
    write_sequnlock(&state->seqlock);
    spin_lock(&state->owner->so_lock);
    update_open_stateflags(state, fmode);
    spin_unlock(&state->owner->so_lock);
}

static int update_open_stateid(struct nfs4_state *state, nfs4_stateid *open_stateid, nfs4_stateid *delegation, fmode_t fmode)
{
    struct nfs_inode *nfsi = NFS_I(state->inode);
    struct nfs_delegation *deleg_cur;
    int ret = 0;

    fmode &= (FMODE_READ|FMODE_WRITE);

    rcu_read_lock();
    deleg_cur = rcu_dereference(nfsi->delegation);
    if (deleg_cur == NULL)
        goto no_delegation;

    spin_lock(&deleg_cur->lock);
    if (nfsi->delegation != deleg_cur ||
        (deleg_cur->type & fmode) != fmode)
        goto no_delegation_unlock;

    if (delegation == NULL)
        delegation = &deleg_cur->stateid;
    else if (!nfs4_stateid_match(&deleg_cur->stateid, delegation))
        goto no_delegation_unlock;

    nfs_mark_delegation_referenced(deleg_cur);
    __update_open_stateid(state, open_stateid, &deleg_cur->stateid, fmode);
    ret = 1;
no_delegation_unlock:
    spin_unlock(&deleg_cur->lock);
no_delegation:
    rcu_read_unlock();

    if (!ret && open_stateid != NULL) {
        __update_open_stateid(state, open_stateid, NULL, fmode);
        ret = 1;
    }

    return ret;
}


static void nfs4_return_incompatible_delegation(struct inode *inode, fmode_t fmode)
{
    struct nfs_delegation *delegation;

    rcu_read_lock();
    delegation = rcu_dereference(NFS_I(inode)->delegation);
    if (delegation == NULL || (delegation->type & fmode) == fmode) {
        rcu_read_unlock();
        return;
    }
    rcu_read_unlock();
    nfs4_inode_return_delegation(inode);
}

static struct nfs4_state *nfs4_try_open_cached(struct nfs4_opendata *opendata)
{
    struct nfs4_state *state = opendata->state;
    struct nfs_inode *nfsi = NFS_I(state->inode);
    struct nfs_delegation *delegation;
    int open_mode = opendata->o_arg.open_flags & (O_EXCL|O_TRUNC);
    fmode_t fmode = opendata->o_arg.fmode;
    nfs4_stateid stateid;
    int ret = -EAGAIN;

    for (;;) {
        if (can_open_cached(state, fmode, open_mode)) {
            spin_lock(&state->owner->so_lock);
            if (can_open_cached(state, fmode, open_mode)) {
                update_open_stateflags(state, fmode);
                spin_unlock(&state->owner->so_lock);
                goto out_return_state;
            }
            spin_unlock(&state->owner->so_lock);
        }
        rcu_read_lock();
        delegation = rcu_dereference(nfsi->delegation);
        if (!can_open_delegated(delegation, fmode)) {
            rcu_read_unlock();
            break;
        }
        /* Save the delegation */
        nfs4_stateid_copy(&stateid, &delegation->stateid);
        rcu_read_unlock();
        ret = nfs_may_open(state->inode, state->owner->so_cred, open_mode);
        if (ret != 0)
            goto out;
        ret = -EAGAIN;

        /* Try to update the stateid using the delegation */
        if (update_open_stateid(state, NULL, &stateid, fmode))
            goto out_return_state;
    }
out:
    return ERR_PTR(ret);
out_return_state:
    atomic_inc(&state->count);
    return state;
}

static void
nfs4_opendata_check_deleg(struct nfs4_opendata *data, struct nfs4_state *state)
{
    struct nfs_client *clp = NFS_SERVER(state->inode)->nfs_client;
    struct nfs_delegation *delegation;
    int delegation_flags = 0;

    rcu_read_lock();
    delegation = rcu_dereference(NFS_I(state->inode)->delegation);
    if (delegation)
        delegation_flags = delegation->flags;
    rcu_read_unlock();
    if (data->o_arg.claim == NFS4_OPEN_CLAIM_DELEGATE_CUR) {
        pr_err_ratelimited("NFS: Broken NFSv4 server %s is "
                   "returning a delegation for "
                   "OPEN(CLAIM_DELEGATE_CUR)\n",
                   clp->cl_hostname);
    } else if ((delegation_flags & 1UL<<NFS_DELEGATION_NEED_RECLAIM) == 0)
        nfs_inode_set_delegation(state->inode,
                     data->owner->so_cred,
                     &data->o_res);
    else
        nfs_inode_reclaim_delegation(state->inode,
                         data->owner->so_cred,
                         &data->o_res);
}

/*
 * Check the inode attributes against the CLAIM_PREVIOUS returned attributes
 * and update the nfs4_state.
 */
static struct nfs4_state *
_nfs4_opendata_reclaim_to_nfs4_state(struct nfs4_opendata *data)
{
    struct inode *inode = data->state->inode;
    struct nfs4_state *state = data->state;
    int ret;

    if (!data->rpc_done) {
        ret = data->rpc_status;
        goto err;
    }

    ret = -ESTALE;
    if (!(data->f_attr.valid & NFS_ATTR_FATTR_TYPE) ||
        !(data->f_attr.valid & NFS_ATTR_FATTR_FILEID) ||
        !(data->f_attr.valid & NFS_ATTR_FATTR_CHANGE))
        goto err;

    ret = -ENOMEM;
    state = nfs4_get_open_state(inode, data->owner);
    if (state == NULL)
        goto err;

    ret = nfs_refresh_inode(inode, &data->f_attr);
    if (ret)
        goto err;

    if (data->o_res.delegation_type != 0)
        nfs4_opendata_check_deleg(data, state);
    update_open_stateid(state, &data->o_res.stateid, NULL,
                data->o_arg.fmode);

    return state;
err:
    return ERR_PTR(ret);

}

static struct nfs4_state *
_nfs4_opendata_to_nfs4_state(struct nfs4_opendata *data)
{
    struct inode *inode;
    struct nfs4_state *state = NULL;
    int ret;

    if (!data->rpc_done) {
        state = nfs4_try_open_cached(data);
        goto out;
    }

    ret = -EAGAIN;
    if (!(data->f_attr.valid & NFS_ATTR_FATTR))
        goto err;
    inode = nfs_fhget(data->dir->d_sb, &data->o_res.fh, &data->f_attr);
    ret = PTR_ERR(inode);
    if (IS_ERR(inode))
        goto err;
    ret = -ENOMEM;
    state = nfs4_get_open_state(inode, data->owner);
    if (state == NULL)
        goto err_put_inode;
    if (data->o_res.delegation_type != 0)
        nfs4_opendata_check_deleg(data, state);
    update_open_stateid(state, &data->o_res.stateid, NULL,
            data->o_arg.fmode);
    iput(inode);
out:
    return state;
err_put_inode:
    iput(inode);
err:
    return ERR_PTR(ret);
}

static struct nfs4_state *
nfs4_opendata_to_nfs4_state(struct nfs4_opendata *data)
{
    if (data->o_arg.claim == NFS4_OPEN_CLAIM_PREVIOUS)
        return _nfs4_opendata_reclaim_to_nfs4_state(data);
    return _nfs4_opendata_to_nfs4_state(data);
}

static struct nfs_open_context *nfs4_state_find_open_context(struct nfs4_state *state)
{
    struct nfs_inode *nfsi = NFS_I(state->inode);
    struct nfs_open_context *ctx;

    spin_lock(&state->inode->i_lock);
    list_for_each_entry(ctx, &nfsi->open_files, list) {
        if (ctx->state != state)
            continue;
        get_nfs_open_context(ctx);
        spin_unlock(&state->inode->i_lock);
        return ctx;
    }
    spin_unlock(&state->inode->i_lock);
    return ERR_PTR(-ENOENT);
}

static struct nfs4_opendata *nfs4_open_recoverdata_alloc(struct nfs_open_context *ctx, struct nfs4_state *state)
{
    struct nfs4_opendata *opendata;

    opendata = nfs4_opendata_alloc(ctx->dentry, state->owner, 0, 0, NULL, GFP_NOFS);
    if (opendata == NULL)
        return ERR_PTR(-ENOMEM);
    opendata->state = state;
    atomic_inc(&state->count);
    return opendata;
}

static int nfs4_open_recover_helper(struct nfs4_opendata *opendata, fmode_t fmode, struct nfs4_state **res)
{
    struct nfs4_state *newstate;
    int ret;

    opendata->o_arg.open_flags = 0;
    opendata->o_arg.fmode = fmode;
    memset(&opendata->o_res, 0, sizeof(opendata->o_res));
    memset(&opendata->c_res, 0, sizeof(opendata->c_res));
    nfs4_init_opendata_res(opendata);
    ret = _nfs4_recover_proc_open(opendata);
    if (ret != 0)
        return ret; 
    newstate = nfs4_opendata_to_nfs4_state(opendata);
    if (IS_ERR(newstate))
        return PTR_ERR(newstate);
    nfs4_close_state(newstate, fmode);
    *res = newstate;
    return 0;
}

static int nfs4_open_recover(struct nfs4_opendata *opendata, struct nfs4_state *state)
{
    struct nfs4_state *newstate;
    int ret;

    /* memory barrier prior to reading state->n_* */
    clear_bit(NFS_DELEGATED_STATE, &state->flags);
    smp_rmb();
    if (state->n_rdwr != 0) {
        clear_bit(NFS_O_RDWR_STATE, &state->flags);
        ret = nfs4_open_recover_helper(opendata, FMODE_READ|FMODE_WRITE, &newstate);
        if (ret != 0)
            return ret;
        if (newstate != state)
            return -ESTALE;
    }
    if (state->n_wronly != 0) {
        clear_bit(NFS_O_WRONLY_STATE, &state->flags);
        ret = nfs4_open_recover_helper(opendata, FMODE_WRITE, &newstate);
        if (ret != 0)
            return ret;
        if (newstate != state)
            return -ESTALE;
    }
    if (state->n_rdonly != 0) {
        clear_bit(NFS_O_RDONLY_STATE, &state->flags);
        ret = nfs4_open_recover_helper(opendata, FMODE_READ, &newstate);
        if (ret != 0)
            return ret;
        if (newstate != state)
            return -ESTALE;
    }
    /*
     * We may have performed cached opens for all three recoveries.
     * Check if we need to update the current stateid.
     */
    if (test_bit(NFS_DELEGATED_STATE, &state->flags) == 0 &&
        !nfs4_stateid_match(&state->stateid, &state->open_stateid)) {
        write_seqlock(&state->seqlock);
        if (test_bit(NFS_DELEGATED_STATE, &state->flags) == 0)
            nfs4_stateid_copy(&state->stateid, &state->open_stateid);
        write_sequnlock(&state->seqlock);
    }
    return 0;
}

/*
 * OPEN_RECLAIM:
 *  reclaim state on the server after a reboot.
 */
static int _nfs4_do_open_reclaim(struct nfs_open_context *ctx, struct nfs4_state *state)
{
    struct nfs_delegation *delegation;
    struct nfs4_opendata *opendata;
    fmode_t delegation_type = 0;
    int status;

    opendata = nfs4_open_recoverdata_alloc(ctx, state);
    if (IS_ERR(opendata))
        return PTR_ERR(opendata);
    opendata->o_arg.claim = NFS4_OPEN_CLAIM_PREVIOUS;
    opendata->o_arg.fh = NFS_FH(state->inode);
    rcu_read_lock();
    delegation = rcu_dereference(NFS_I(state->inode)->delegation);
    if (delegation != NULL && test_bit(NFS_DELEGATION_NEED_RECLAIM, &delegation->flags) != 0)
        delegation_type = delegation->type;
    rcu_read_unlock();
    opendata->o_arg.u.delegation_type = delegation_type;
    status = nfs4_open_recover(opendata, state);
    nfs4_opendata_put(opendata);
    return status;
}

static int nfs4_do_open_reclaim(struct nfs_open_context *ctx, struct nfs4_state *state)
{
    struct nfs_server *server = NFS_SERVER(state->inode);
    struct nfs4_exception exception = { };
    int err;
    do {
        err = _nfs4_do_open_reclaim(ctx, state);
        if (err != -NFS4ERR_DELAY)
            break;
        nfs4_handle_exception(server, err, &exception);
    } while (exception.retry);
    return err;
}

static int nfs4_open_reclaim(struct nfs4_state_owner *sp, struct nfs4_state *state)
{
    struct nfs_open_context *ctx;
    int ret;

    ctx = nfs4_state_find_open_context(state);
    if (IS_ERR(ctx))
        return PTR_ERR(ctx);
    ret = nfs4_do_open_reclaim(ctx, state);
    put_nfs_open_context(ctx);
    return ret;
}

static int _nfs4_open_delegation_recall(struct nfs_open_context *ctx, struct nfs4_state *state, const nfs4_stateid *stateid)
{
    struct nfs4_opendata *opendata;
    int ret;

    opendata = nfs4_open_recoverdata_alloc(ctx, state);
    if (IS_ERR(opendata))
        return PTR_ERR(opendata);
    opendata->o_arg.claim = NFS4_OPEN_CLAIM_DELEGATE_CUR;
    nfs4_stateid_copy(&opendata->o_arg.u.delegation, stateid);
    ret = nfs4_open_recover(opendata, state);
    nfs4_opendata_put(opendata);
    return ret;
}

int nfs4_open_delegation_recall(struct nfs_open_context *ctx, struct nfs4_state *state, const nfs4_stateid *stateid)
{
    struct nfs4_exception exception = { };
    struct nfs_server *server = NFS_SERVER(state->inode);
    int err;
    do {
        err = _nfs4_open_delegation_recall(ctx, state, stateid);
        switch (err) {
            case 0:
            case -ENOENT:
            case -ESTALE:
                goto out;
            case -NFS4ERR_BADSESSION:
            case -NFS4ERR_BADSLOT:
            case -NFS4ERR_BAD_HIGH_SLOT:
            case -NFS4ERR_CONN_NOT_BOUND_TO_SESSION:
            case -NFS4ERR_DEADSESSION:
                nfs4_schedule_session_recovery(server->nfs_client->cl_session, err);
                goto out;
            case -NFS4ERR_STALE_CLIENTID:
            case -NFS4ERR_STALE_STATEID:
            case -NFS4ERR_EXPIRED:
                /* Don't recall a delegation if it was lost */
                nfs4_schedule_lease_recovery(server->nfs_client);
                goto out;
            case -ERESTARTSYS:
                /*
                 * The show must go on: exit, but mark the
                 * stateid as needing recovery.
                 */
            case -NFS4ERR_DELEG_REVOKED:
            case -NFS4ERR_ADMIN_REVOKED:
            case -NFS4ERR_BAD_STATEID:
                nfs_inode_find_state_and_recover(state->inode,
                        stateid);
                nfs4_schedule_stateid_recovery(server, state);
            case -EKEYEXPIRED:
                /*
                 * User RPCSEC_GSS context has expired.
                 * We cannot recover this stateid now, so
                 * skip it and allow recovery thread to
                 * proceed.
                 */
            case -ENOMEM:
                err = 0;
                goto out;
        }
        err = nfs4_handle_exception(server, err, &exception);
    } while (exception.retry);
out:
    return err;
}

static void nfs4_open_confirm_done(struct rpc_task *task, void *calldata)
{
    struct nfs4_opendata *data = calldata;

    data->rpc_status = task->tk_status;
    if (data->rpc_status == 0) {
        nfs4_stateid_copy(&data->o_res.stateid, &data->c_res.stateid);
        nfs_confirm_seqid(&data->owner->so_seqid, 0);
        renew_lease(data->o_res.server, data->timestamp);
        data->rpc_done = 1;
    }
}

static void nfs4_open_confirm_release(void *calldata)
{
    struct nfs4_opendata *data = calldata;
    struct nfs4_state *state = NULL;

    /* If this request hasn't been cancelled, do nothing */
    if (data->cancelled == 0)
        goto out_free;
    /* In case of error, no cleanup! */
    if (!data->rpc_done)
        goto out_free;
    state = nfs4_opendata_to_nfs4_state(data);
    if (!IS_ERR(state))
        nfs4_close_state(state, data->o_arg.fmode);
out_free:
    nfs4_opendata_put(data);
}

static const struct rpc_call_ops nfs4_open_confirm_ops = {
    .rpc_call_done = nfs4_open_confirm_done,
    .rpc_release = nfs4_open_confirm_release,
};

/*
 * Note: On error, nfs4_proc_open_confirm will free the struct nfs4_opendata
 */
static int _nfs4_proc_open_confirm(struct nfs4_opendata *data)
{
    struct nfs_server *server = NFS_SERVER(data->dir->d_inode);
    struct rpc_task *task;
    struct  rpc_message msg = {
        .rpc_proc = &nfs4_procedures[NFSPROC4_CLNT_OPEN_CONFIRM],
        .rpc_argp = &data->c_arg,
        .rpc_resp = &data->c_res,
        .rpc_cred = data->owner->so_cred,
    };
    struct rpc_task_setup task_setup_data = {
        .rpc_client = server->client,
        .rpc_message = &msg,
        .callback_ops = &nfs4_open_confirm_ops,
        .callback_data = data,
        .workqueue = nfsiod_workqueue,
        .flags = RPC_TASK_ASYNC,
    };
    int status;

    kref_get(&data->kref);
    data->rpc_done = 0;
    data->rpc_status = 0;
    data->timestamp = jiffies;
    task = rpc_run_task(&task_setup_data);
    if (IS_ERR(task))
        return PTR_ERR(task);
    status = nfs4_wait_for_completion_rpc_task(task);
    if (status != 0) {
        data->cancelled = 1;
        smp_wmb();
    } else
        status = data->rpc_status;
    rpc_put_task(task);
    return status;
}

static void nfs4_open_prepare(struct rpc_task *task, void *calldata)
{
    struct nfs4_opendata *data = calldata;
    struct nfs4_state_owner *sp = data->owner;

    if (nfs_wait_on_sequence(data->o_arg.seqid, task) != 0)
        return;
    /*
     * Check if we still need to send an OPEN call, or if we can use
     * a delegation instead.
     */
    if (data->state != NULL) {
        struct nfs_delegation *delegation;

        if (can_open_cached(data->state, data->o_arg.fmode, data->o_arg.open_flags))
            goto out_no_action;
        rcu_read_lock();
        delegation = rcu_dereference(NFS_I(data->state->inode)->delegation);
        if (data->o_arg.claim != NFS4_OPEN_CLAIM_DELEGATE_CUR &&
            can_open_delegated(delegation, data->o_arg.fmode))
            goto unlock_no_action;
        rcu_read_unlock();
    }
    /* Update client id. */
    data->o_arg.clientid = sp->so_server->nfs_client->cl_clientid;
    if (data->o_arg.claim == NFS4_OPEN_CLAIM_PREVIOUS) {
        task->tk_msg.rpc_proc = &nfs4_procedures[NFSPROC4_CLNT_OPEN_NOATTR];
        data->o_arg.open_bitmap = &nfs4_open_noattr_bitmap[0];
        nfs_copy_fh(&data->o_res.fh, data->o_arg.fh);
    }
    data->timestamp = jiffies;
    if (nfs4_setup_sequence(data->o_arg.server,
                &data->o_arg.seq_args,
                &data->o_res.seq_res,
                task) != 0)
        nfs_release_seqid(data->o_arg.seqid);
    else
        rpc_call_start(task);
    return;
unlock_no_action:
    rcu_read_unlock();
out_no_action:
    task->tk_action = NULL;

}

static void nfs4_recover_open_prepare(struct rpc_task *task, void *calldata)
{
    rpc_task_set_priority(task, RPC_PRIORITY_PRIVILEGED);
    nfs4_open_prepare(task, calldata);
}

static void nfs4_open_done(struct rpc_task *task, void *calldata)
{
    struct nfs4_opendata *data = calldata;

    data->rpc_status = task->tk_status;

    if (!nfs4_sequence_done(task, &data->o_res.seq_res))
        return;

    if (task->tk_status == 0) {
        if (data->o_res.f_attr->valid & NFS_ATTR_FATTR_TYPE) {
            switch (data->o_res.f_attr->mode & S_IFMT) {
            case S_IFREG:
                break;
            case S_IFLNK:
                data->rpc_status = -ELOOP;
                break;
            case S_IFDIR:
                data->rpc_status = -EISDIR;
                break;
            default:
                data->rpc_status = -ENOTDIR;
            }
        }
        renew_lease(data->o_res.server, data->timestamp);
        if (!(data->o_res.rflags & NFS4_OPEN_RESULT_CONFIRM))
            nfs_confirm_seqid(&data->owner->so_seqid, 0);
    }
    data->rpc_done = 1;
}

static void nfs4_open_release(void *calldata)
{
    struct nfs4_opendata *data = calldata;
    struct nfs4_state *state = NULL;

    /* If this request hasn't been cancelled, do nothing */
    if (data->cancelled == 0)
        goto out_free;
    /* In case of error, no cleanup! */
    if (data->rpc_status != 0 || !data->rpc_done)
        goto out_free;
    /* In case we need an open_confirm, no cleanup! */
    if (data->o_res.rflags & NFS4_OPEN_RESULT_CONFIRM)
        goto out_free;
    state = nfs4_opendata_to_nfs4_state(data);
    if (!IS_ERR(state))
        nfs4_close_state(state, data->o_arg.fmode);
out_free:
    nfs4_opendata_put(data);
}

static const struct rpc_call_ops nfs4_open_ops = {
    .rpc_call_prepare = nfs4_open_prepare,
    .rpc_call_done = nfs4_open_done,
    .rpc_release = nfs4_open_release,
};

static const struct rpc_call_ops nfs4_recover_open_ops = {
    .rpc_call_prepare = nfs4_recover_open_prepare,
    .rpc_call_done = nfs4_open_done,
    .rpc_release = nfs4_open_release,
};

static int nfs4_run_open_task(struct nfs4_opendata *data, int isrecover)
{
    struct inode *dir = data->dir->d_inode;
    struct nfs_server *server = NFS_SERVER(dir);
    struct nfs_openargs *o_arg = &data->o_arg;
    struct nfs_openres *o_res = &data->o_res;
    struct rpc_task *task;
    struct rpc_message msg = {
        .rpc_proc = &nfs4_procedures[NFSPROC4_CLNT_OPEN],
        .rpc_argp = o_arg,
        .rpc_resp = o_res,
        .rpc_cred = data->owner->so_cred,
    };
    struct rpc_task_setup task_setup_data = {
        .rpc_client = server->client,
        .rpc_message = &msg,
        .callback_ops = &nfs4_open_ops,
        .callback_data = data,
        .workqueue = nfsiod_workqueue,
        .flags = RPC_TASK_ASYNC,
    };
    int status;

    nfs41_init_sequence(&o_arg->seq_args, &o_res->seq_res, 1);
    kref_get(&data->kref);
    data->rpc_done = 0;
    data->rpc_status = 0;
    data->cancelled = 0;
    if (isrecover)
        task_setup_data.callback_ops = &nfs4_recover_open_ops;
    task = rpc_run_task(&task_setup_data);
        if (IS_ERR(task))
                return PTR_ERR(task);
        status = nfs4_wait_for_completion_rpc_task(task);
        if (status != 0) {
                data->cancelled = 1;
                smp_wmb();
        } else
                status = data->rpc_status;
        rpc_put_task(task);

    return status;
}

static int _nfs4_recover_proc_open(struct nfs4_opendata *data)
{
    struct inode *dir = data->dir->d_inode;
    struct nfs_openres *o_res = &data->o_res;
        int status;

    status = nfs4_run_open_task(data, 1);
    if (status != 0 || !data->rpc_done)
        return status;

    nfs_fattr_map_and_free_names(NFS_SERVER(dir), &data->f_attr);

    if (o_res->rflags & NFS4_OPEN_RESULT_CONFIRM) {
        status = _nfs4_proc_open_confirm(data);
        if (status != 0)
            return status;
    }

    return status;
}

static int nfs4_opendata_access(struct rpc_cred *cred,
                struct nfs4_opendata *opendata,
                struct nfs4_state *state, fmode_t fmode)
{
    struct nfs_access_entry cache;
    u32 mask;

    /* access call failed or for some reason the server doesn't
     * support any access modes -- defer access call until later */
    if (opendata->o_res.access_supported == 0)
        return 0;

    mask = 0;
    /* don't check MAY_WRITE - a newly created file may not have
     * write mode bits, but POSIX allows the creating process to write */
    if (fmode & FMODE_READ)
        mask |= MAY_READ;
    if (fmode & FMODE_EXEC)
        mask |= MAY_EXEC;

    cache.cred = cred;
    cache.jiffies = jiffies;
    nfs_access_set_mask(&cache, opendata->o_res.access_result);
    nfs_access_add_cache(state->inode, &cache);

    if ((mask & ~cache.mask & (MAY_READ | MAY_EXEC)) == 0)
        return 0;

    /* even though OPEN succeeded, access is denied. Close the file */
    nfs4_close_state(state, fmode);
    return -EACCES;
}

/*
 * Note: On error, nfs4_proc_open will free the struct nfs4_opendata
 */
static int _nfs4_proc_open(struct nfs4_opendata *data)
{
    struct inode *dir = data->dir->d_inode;
    struct nfs_server *server = NFS_SERVER(dir);
    struct nfs_openargs *o_arg = &data->o_arg;
    struct nfs_openres *o_res = &data->o_res;
    int status;

    status = nfs4_run_open_task(data, 0);
    if (!data->rpc_done)
        return status;
    if (status != 0) {
        if (status == -NFS4ERR_BADNAME &&
                !(o_arg->open_flags & O_CREAT))
            return -ENOENT;
        return status;
    }

    nfs_fattr_map_and_free_names(server, &data->f_attr);

    if (o_arg->open_flags & O_CREAT)
        update_changeattr(dir, &o_res->cinfo);
    if ((o_res->rflags & NFS4_OPEN_RESULT_LOCKTYPE_POSIX) == 0)
        server->caps &= ~NFS_CAP_POSIX_LOCK;
    if(o_res->rflags & NFS4_OPEN_RESULT_CONFIRM) {
        status = _nfs4_proc_open_confirm(data);
        if (status != 0)
            return status;
    }
    if (!(o_res->f_attr->valid & NFS_ATTR_FATTR))
        _nfs4_proc_getattr(server, &o_res->fh, o_res->f_attr);
    return 0;
}

static int nfs4_client_recover_expired_lease(struct nfs_client *clp)
{
    unsigned int loop;
    int ret;

    for (loop = NFS4_MAX_LOOP_ON_RECOVER; loop != 0; loop--) {
        ret = nfs4_wait_clnt_recover(clp);
        if (ret != 0)
            break;
        if (!test_bit(NFS4CLNT_LEASE_EXPIRED, &clp->cl_state) &&
            !test_bit(NFS4CLNT_CHECK_LEASE,&clp->cl_state))
            break;
        nfs4_schedule_state_manager(clp);
        ret = -EIO;
    }
    return ret;
}

static int nfs4_recover_expired_lease(struct nfs_server *server)
{
    return nfs4_client_recover_expired_lease(server->nfs_client);
}

/*
 * OPEN_EXPIRED:
 *  reclaim state on the server after a network partition.
 *  Assumes caller holds the appropriate lock
 */
static int _nfs4_open_expired(struct nfs_open_context *ctx, struct nfs4_state *state)
{
    struct nfs4_opendata *opendata;
    int ret;

    opendata = nfs4_open_recoverdata_alloc(ctx, state);
    if (IS_ERR(opendata))
        return PTR_ERR(opendata);
    ret = nfs4_open_recover(opendata, state);
    if (ret == -ESTALE)
        d_drop(ctx->dentry);
    nfs4_opendata_put(opendata);
    return ret;
}

static int nfs4_do_open_expired(struct nfs_open_context *ctx, struct nfs4_state *state)
{
    struct nfs_server *server = NFS_SERVER(state->inode);
    struct nfs4_exception exception = { };
    int err;

    do {
        err = _nfs4_open_expired(ctx, state);
        switch (err) {
        default:
            goto out;
        case -NFS4ERR_GRACE:
        case -NFS4ERR_DELAY:
            nfs4_handle_exception(server, err, &exception);
            err = 0;
        }
    } while (exception.retry);
out:
    return err;
}

static int nfs4_open_expired(struct nfs4_state_owner *sp, struct nfs4_state *state)
{
    struct nfs_open_context *ctx;
    int ret;

    ctx = nfs4_state_find_open_context(state);
    if (IS_ERR(ctx))
        return PTR_ERR(ctx);
    ret = nfs4_do_open_expired(ctx, state);
    put_nfs_open_context(ctx);
    return ret;
}

#if defined(CONFIG_NFS_V4_1)
static void nfs41_clear_delegation_stateid(struct nfs4_state *state)
{
    struct nfs_server *server = NFS_SERVER(state->inode);
    nfs4_stateid *stateid = &state->stateid;
    int status;

    /* If a state reset has been done, test_stateid is unneeded */
    if (test_bit(NFS_DELEGATED_STATE, &state->flags) == 0)
        return;

    status = nfs41_test_stateid(server, stateid);
    if (status != NFS_OK) {
        /* Free the stateid unless the server explicitly
         * informs us the stateid is unrecognized. */
        if (status != -NFS4ERR_BAD_STATEID)
            nfs41_free_stateid(server, stateid);
        nfs_remove_bad_delegation(state->inode);

        write_seqlock(&state->seqlock);
        nfs4_stateid_copy(&state->stateid, &state->open_stateid);
        write_sequnlock(&state->seqlock);
        clear_bit(NFS_DELEGATED_STATE, &state->flags);
    }
}

static int nfs41_check_open_stateid(struct nfs4_state *state)
{
    struct nfs_server *server = NFS_SERVER(state->inode);
    nfs4_stateid *stateid = &state->open_stateid;
    int status;

    /* If a state reset has been done, test_stateid is unneeded */
    if ((test_bit(NFS_O_RDONLY_STATE, &state->flags) == 0) &&
        (test_bit(NFS_O_WRONLY_STATE, &state->flags) == 0) &&
        (test_bit(NFS_O_RDWR_STATE, &state->flags) == 0))
        return -NFS4ERR_BAD_STATEID;

    status = nfs41_test_stateid(server, stateid);
    if (status != NFS_OK) {
        /* Free the stateid unless the server explicitly
         * informs us the stateid is unrecognized. */
        if (status != -NFS4ERR_BAD_STATEID)
            nfs41_free_stateid(server, stateid);

        clear_bit(NFS_O_RDONLY_STATE, &state->flags);
        clear_bit(NFS_O_WRONLY_STATE, &state->flags);
        clear_bit(NFS_O_RDWR_STATE, &state->flags);
    }
    return status;
}

static int nfs41_open_expired(struct nfs4_state_owner *sp, struct nfs4_state *state)
{
    int status;

    nfs41_clear_delegation_stateid(state);
    status = nfs41_check_open_stateid(state);
    if (status != NFS_OK)
        status = nfs4_open_expired(sp, state);
    return status;
}
#endif

/*
 * on an EXCLUSIVE create, the server should send back a bitmask with FATTR4-*
 * fields corresponding to attributes that were used to store the verifier.
 * Make sure we clobber those fields in the later setattr call
 */
static inline void nfs4_exclusive_attrset(struct nfs4_opendata *opendata, struct iattr *sattr)
{
    if ((opendata->o_res.attrset[1] & FATTR4_WORD1_TIME_ACCESS) &&
        !(sattr->ia_valid & ATTR_ATIME_SET))
        sattr->ia_valid |= ATTR_ATIME;

    if ((opendata->o_res.attrset[1] & FATTR4_WORD1_TIME_MODIFY) &&
        !(sattr->ia_valid & ATTR_MTIME_SET))
        sattr->ia_valid |= ATTR_MTIME;
}

/*
 * Returns a referenced nfs4_state
 */
static int _nfs4_do_open(struct inode *dir,
            struct dentry *dentry,
            fmode_t fmode,
            int flags,
            struct iattr *sattr,
            struct rpc_cred *cred,
            struct nfs4_state **res,
            struct nfs4_threshold **ctx_th)
{
    struct nfs4_state_owner  *sp;
    struct nfs4_state     *state = NULL;
    struct nfs_server       *server = NFS_SERVER(dir);
    struct nfs4_opendata *opendata;
    int status;

    /* Protect against reboot recovery conflicts */
    status = -ENOMEM;
    sp = nfs4_get_state_owner(server, cred, GFP_KERNEL);
    if (sp == NULL) {
        dprintk("nfs4_do_open: nfs4_get_state_owner failed!\n");
        goto out_err;
    }
    status = nfs4_recover_expired_lease(server);
    if (status != 0)
        goto err_put_state_owner;
    if (dentry->d_inode != NULL)
        nfs4_return_incompatible_delegation(dentry->d_inode, fmode);
    status = -ENOMEM;
    opendata = nfs4_opendata_alloc(dentry, sp, fmode, flags, sattr, GFP_KERNEL);
    if (opendata == NULL)
        goto err_put_state_owner;

    if (ctx_th && server->attr_bitmask[2] & FATTR4_WORD2_MDSTHRESHOLD) {
        opendata->f_attr.mdsthreshold = pnfs_mdsthreshold_alloc();
        if (!opendata->f_attr.mdsthreshold)
            goto err_opendata_put;
        opendata->o_arg.open_bitmap = &nfs4_pnfs_open_bitmap[0];
    }
    if (dentry->d_inode != NULL)
        opendata->state = nfs4_get_open_state(dentry->d_inode, sp);

    status = _nfs4_proc_open(opendata);
    if (status != 0)
        goto err_opendata_put;

    state = nfs4_opendata_to_nfs4_state(opendata);
    status = PTR_ERR(state);
    if (IS_ERR(state))
        goto err_opendata_put;
    if (server->caps & NFS_CAP_POSIX_LOCK)
        set_bit(NFS_STATE_POSIX_LOCKS, &state->flags);

    status = nfs4_opendata_access(cred, opendata, state, fmode);
    if (status != 0)
        goto err_opendata_put;

    if (opendata->o_arg.open_flags & O_EXCL) {
        nfs4_exclusive_attrset(opendata, sattr);

        nfs_fattr_init(opendata->o_res.f_attr);
        status = nfs4_do_setattr(state->inode, cred,
                opendata->o_res.f_attr, sattr,
                state);
        if (status == 0)
            nfs_setattr_update_inode(state->inode, sattr);
        nfs_post_op_update_inode(state->inode, opendata->o_res.f_attr);
    }

    if (pnfs_use_threshold(ctx_th, opendata->f_attr.mdsthreshold, server))
        *ctx_th = opendata->f_attr.mdsthreshold;
    else
        kfree(opendata->f_attr.mdsthreshold);
    opendata->f_attr.mdsthreshold = NULL;

    nfs4_opendata_put(opendata);
    nfs4_put_state_owner(sp);
    *res = state;
    return 0;
err_opendata_put:
    kfree(opendata->f_attr.mdsthreshold);
    nfs4_opendata_put(opendata);
err_put_state_owner:
    nfs4_put_state_owner(sp);
out_err:
    *res = NULL;
    return status;
}


static struct nfs4_state *nfs4_do_open(struct inode *dir,
                    struct dentry *dentry,
                    fmode_t fmode,
                    int flags,
                    struct iattr *sattr,
                    struct rpc_cred *cred,
                    struct nfs4_threshold **ctx_th)
{
    struct nfs4_exception exception = { };
    struct nfs4_state *res;
    int status;

    fmode &= FMODE_READ|FMODE_WRITE|FMODE_EXEC;
    do {
        status = _nfs4_do_open(dir, dentry, fmode, flags, sattr, cred,
                       &res, ctx_th);
        if (status == 0)
            break;
        /* NOTE: BAD_SEQID means the server and client disagree about the
         * book-keeping w.r.t. state-changing operations
         * (OPEN/CLOSE/LOCK/LOCKU...)
         * It is actually a sign of a bug on the client or on the server.
         *
         * If we receive a BAD_SEQID error in the particular case of
         * doing an OPEN, we assume that nfs_increment_open_seqid() will
         * have unhashed the old state_owner for us, and that we can
         * therefore safely retry using a new one. We should still warn
         * the user though...
         */
        if (status == -NFS4ERR_BAD_SEQID) {
            pr_warn_ratelimited("NFS: v4 server %s "
                    " returned a bad sequence-id error!\n",
                    NFS_SERVER(dir)->nfs_client->cl_hostname);
            exception.retry = 1;
            continue;
        }
        /*
         * BAD_STATEID on OPEN means that the server cancelled our
         * state before it received the OPEN_CONFIRM.
         * Recover by retrying the request as per the discussion
         * on Page 181 of RFC3530.
         */
        if (status == -NFS4ERR_BAD_STATEID) {
            exception.retry = 1;
            continue;
        }
        if (status == -EAGAIN) {
            /* We must have found a delegation */
            exception.retry = 1;
            continue;
        }
        res = ERR_PTR(nfs4_handle_exception(NFS_SERVER(dir),
                    status, &exception));
    } while (exception.retry);
    return res;
}

static int _nfs4_do_setattr(struct inode *inode, struct rpc_cred *cred,
                struct nfs_fattr *fattr, struct iattr *sattr,
                struct nfs4_state *state)
{
    struct nfs_server *server = NFS_SERVER(inode);
        struct nfs_setattrargs  arg = {
                .fh             = NFS_FH(inode),
                .iap            = sattr,
        .server     = server,
        .bitmask = server->attr_bitmask,
        };
        struct nfs_setattrres  res = {
        .fattr      = fattr,
        .server     = server,
        };
        struct rpc_message msg = {
        .rpc_proc   = &nfs4_procedures[NFSPROC4_CLNT_SETATTR],
        .rpc_argp   = &arg,
        .rpc_resp   = &res,
        .rpc_cred   = cred,
        };
    unsigned long timestamp = jiffies;
    int status;

    nfs_fattr_init(fattr);

    if (state != NULL) {
        struct nfs_lockowner lockowner = {
            .l_owner = current->files,
            .l_pid = current->tgid,
        };
        nfs4_select_rw_stateid(&arg.stateid, state, FMODE_WRITE,
                &lockowner);
    } else if (nfs4_copy_delegation_stateid(&arg.stateid, inode,
                FMODE_WRITE)) {
        /* Use that stateid */
    } else
        nfs4_stateid_copy(&arg.stateid, &zero_stateid);

    status = nfs4_call_sync(server->client, server, &msg, &arg.seq_args, &res.seq_res, 1);
    if (status == 0 && state != NULL)
        renew_lease(server, timestamp);
    return status;
}

static int nfs4_do_setattr(struct inode *inode, struct rpc_cred *cred,
               struct nfs_fattr *fattr, struct iattr *sattr,
               struct nfs4_state *state)
{
    struct nfs_server *server = NFS_SERVER(inode);
    struct nfs4_exception exception = {
        .state = state,
        .inode = inode,
    };
    int err;
    do {
        err = _nfs4_do_setattr(inode, cred, fattr, sattr, state);
        switch (err) {
        case -NFS4ERR_OPENMODE:
            if (state && !(state->state & FMODE_WRITE)) {
                err = -EBADF;
                if (sattr->ia_valid & ATTR_OPEN)
                    err = -EACCES;
                goto out;
            }
        }
        err = nfs4_handle_exception(server, err, &exception);
    } while (exception.retry);
out:
    return err;
}

struct nfs4_closedata {
    struct inode *inode;
    struct nfs4_state *state;
    struct nfs_closeargs arg;
    struct nfs_closeres res;
    struct nfs_fattr fattr;
    unsigned long timestamp;
    bool roc;
    u32 roc_barrier;
};

static void nfs4_free_closedata(void *data)
{
    struct nfs4_closedata *calldata = data;
    struct nfs4_state_owner *sp = calldata->state->owner;
    struct super_block *sb = calldata->state->inode->i_sb;

    if (calldata->roc)
        pnfs_roc_release(calldata->state->inode);
    nfs4_put_open_state(calldata->state);
    nfs_free_seqid(calldata->arg.seqid);
    nfs4_put_state_owner(sp);
    nfs_sb_deactive_async(sb);
    kfree(calldata);
}

static void nfs4_close_clear_stateid_flags(struct nfs4_state *state,
        fmode_t fmode)
{
    spin_lock(&state->owner->so_lock);
    if (!(fmode & FMODE_READ))
        clear_bit(NFS_O_RDONLY_STATE, &state->flags);
    if (!(fmode & FMODE_WRITE))
        clear_bit(NFS_O_WRONLY_STATE, &state->flags);
    clear_bit(NFS_O_RDWR_STATE, &state->flags);
    spin_unlock(&state->owner->so_lock);
}

static void nfs4_close_done(struct rpc_task *task, void *data)
{
    struct nfs4_closedata *calldata = data;
    struct nfs4_state *state = calldata->state;
    struct nfs_server *server = NFS_SERVER(calldata->inode);

    dprintk("%s: begin!\n", __func__);
    if (!nfs4_sequence_done(task, &calldata->res.seq_res))
        return;
        /* hmm. we are done with the inode, and in the process of freeing
     * the state_owner. we keep this around to process errors
     */
    switch (task->tk_status) {
        case 0:
            if (calldata->roc)
                pnfs_roc_set_barrier(state->inode,
                             calldata->roc_barrier);
            nfs_set_open_stateid(state, &calldata->res.stateid, 0);
            renew_lease(server, calldata->timestamp);
            nfs4_close_clear_stateid_flags(state,
                    calldata->arg.fmode);
            break;
        case -NFS4ERR_STALE_STATEID:
        case -NFS4ERR_OLD_STATEID:
        case -NFS4ERR_BAD_STATEID:
        case -NFS4ERR_EXPIRED:
            if (calldata->arg.fmode == 0)
                break;
        default:
            if (nfs4_async_handle_error(task, server, state) == -EAGAIN)
                rpc_restart_call_prepare(task);
    }
    nfs_release_seqid(calldata->arg.seqid);
    nfs_refresh_inode(calldata->inode, calldata->res.fattr);
    dprintk("%s: done, ret = %d!\n", __func__, task->tk_status);
}

static void nfs4_close_prepare(struct rpc_task *task, void *data)
{
    struct nfs4_closedata *calldata = data;
    struct nfs4_state *state = calldata->state;
    struct inode *inode = calldata->inode;
    int call_close = 0;

    dprintk("%s: begin!\n", __func__);
    if (nfs_wait_on_sequence(calldata->arg.seqid, task) != 0)
        return;

    task->tk_msg.rpc_proc = &nfs4_procedures[NFSPROC4_CLNT_OPEN_DOWNGRADE];
    calldata->arg.fmode = FMODE_READ|FMODE_WRITE;
    spin_lock(&state->owner->so_lock);
    /* Calculate the change in open mode */
    if (state->n_rdwr == 0) {
        if (state->n_rdonly == 0) {
            call_close |= test_bit(NFS_O_RDONLY_STATE, &state->flags);
            call_close |= test_bit(NFS_O_RDWR_STATE, &state->flags);
            calldata->arg.fmode &= ~FMODE_READ;
        }
        if (state->n_wronly == 0) {
            call_close |= test_bit(NFS_O_WRONLY_STATE, &state->flags);
            call_close |= test_bit(NFS_O_RDWR_STATE, &state->flags);
            calldata->arg.fmode &= ~FMODE_WRITE;
        }
    }
    spin_unlock(&state->owner->so_lock);

    if (!call_close) {
        /* Note: exit _without_ calling nfs4_close_done */
        task->tk_action = NULL;
        goto out;
    }

    if (calldata->arg.fmode == 0) {
        task->tk_msg.rpc_proc = &nfs4_procedures[NFSPROC4_CLNT_CLOSE];
        if (calldata->roc &&
            pnfs_roc_drain(inode, &calldata->roc_barrier, task))
            goto out;
    }

    nfs_fattr_init(calldata->res.fattr);
    calldata->timestamp = jiffies;
    if (nfs4_setup_sequence(NFS_SERVER(inode),
                &calldata->arg.seq_args,
                &calldata->res.seq_res,
                task) != 0)
        nfs_release_seqid(calldata->arg.seqid);
    else
        rpc_call_start(task);
out:
    dprintk("%s: done!\n", __func__);
}

static const struct rpc_call_ops nfs4_close_ops = {
    .rpc_call_prepare = nfs4_close_prepare,
    .rpc_call_done = nfs4_close_done,
    .rpc_release = nfs4_free_closedata,
};

/* 
 * It is possible for data to be read/written from a mem-mapped file 
 * after the sys_close call (which hits the vfs layer as a flush).
 * This means that we can't safely call nfsv4 close on a file until 
 * the inode is cleared. This in turn means that we are not good
 * NFSv4 citizens - we do not indicate to the server to update the file's 
 * share state even when we are done with one of the three share 
 * stateid's in the inode.
 *
 * NOTE: Caller must be holding the sp->so_owner semaphore!
 */
int nfs4_do_close(struct nfs4_state *state, gfp_t gfp_mask, int wait)
{
    struct nfs_server *server = NFS_SERVER(state->inode);
    struct nfs4_closedata *calldata;
    struct nfs4_state_owner *sp = state->owner;
    struct rpc_task *task;
    struct rpc_message msg = {
        .rpc_proc = &nfs4_procedures[NFSPROC4_CLNT_CLOSE],
        .rpc_cred = state->owner->so_cred,
    };
    struct rpc_task_setup task_setup_data = {
        .rpc_client = server->client,
        .rpc_message = &msg,
        .callback_ops = &nfs4_close_ops,
        .workqueue = nfsiod_workqueue,
        .flags = RPC_TASK_ASYNC,
    };
    int status = -ENOMEM;

    calldata = kzalloc(sizeof(*calldata), gfp_mask);
    if (calldata == NULL)
        goto out;
    nfs41_init_sequence(&calldata->arg.seq_args, &calldata->res.seq_res, 1);
    calldata->inode = state->inode;
    calldata->state = state;
    calldata->arg.fh = NFS_FH(state->inode);
    calldata->arg.stateid = &state->open_stateid;
    /* Serialization for the sequence id */
    calldata->arg.seqid = nfs_alloc_seqid(&state->owner->so_seqid, gfp_mask);
    if (calldata->arg.seqid == NULL)
        goto out_free_calldata;
    calldata->arg.fmode = 0;
    calldata->arg.bitmask = server->cache_consistency_bitmask;
    calldata->res.fattr = &calldata->fattr;
    calldata->res.seqid = calldata->arg.seqid;
    calldata->res.server = server;
    calldata->roc = pnfs_roc(state->inode);
    nfs_sb_active(calldata->inode->i_sb);

    msg.rpc_argp = &calldata->arg;
    msg.rpc_resp = &calldata->res;
    task_setup_data.callback_data = calldata;
    task = rpc_run_task(&task_setup_data);
    if (IS_ERR(task))
        return PTR_ERR(task);
    status = 0;
    if (wait)
        status = rpc_wait_for_completion_task(task);
    rpc_put_task(task);
    return status;
out_free_calldata:
    kfree(calldata);
out:
    nfs4_put_open_state(state);
    nfs4_put_state_owner(sp);
    return status;
}

static struct inode *
nfs4_atomic_open(struct inode *dir, struct nfs_open_context *ctx, int open_flags, struct iattr *attr)
{
    struct nfs4_state *state;

    /* Protect against concurrent sillydeletes */
    state = nfs4_do_open(dir, ctx->dentry, ctx->mode, open_flags, attr,
                 ctx->cred, &ctx->mdsthreshold);
    if (IS_ERR(state))
        return ERR_CAST(state);
    ctx->state = state;
    return igrab(state->inode);
}

static void nfs4_close_context(struct nfs_open_context *ctx, int is_sync)
{
    if (ctx->state == NULL)
        return;
    if (is_sync)
        nfs4_close_sync(ctx->state, ctx->mode);
    else
        nfs4_close_state(ctx->state, ctx->mode);
}

static int _nfs4_server_capabilities(struct nfs_server *server, struct nfs_fh *fhandle)
{
    struct nfs4_server_caps_arg args = {
        .fhandle = fhandle,
    };
    struct nfs4_server_caps_res res = {};
    struct rpc_message msg = {
        .rpc_proc = &nfs4_procedures[NFSPROC4_CLNT_SERVER_CAPS],
        .rpc_argp = &args,
        .rpc_resp = &res,
    };
    int status;

    status = nfs4_call_sync(server->client, server, &msg, &args.seq_args, &res.seq_res, 0);
    if (status == 0) {
        memcpy(server->attr_bitmask, res.attr_bitmask, sizeof(server->attr_bitmask));
        server->caps &= ~(NFS_CAP_ACLS|NFS_CAP_HARDLINKS|
                NFS_CAP_SYMLINKS|NFS_CAP_FILEID|
                NFS_CAP_MODE|NFS_CAP_NLINK|NFS_CAP_OWNER|
                NFS_CAP_OWNER_GROUP|NFS_CAP_ATIME|
                NFS_CAP_CTIME|NFS_CAP_MTIME);
        if (res.attr_bitmask[0] & FATTR4_WORD0_ACL)
            server->caps |= NFS_CAP_ACLS;
        if (res.has_links != 0)
            server->caps |= NFS_CAP_HARDLINKS;
        if (res.has_symlinks != 0)
            server->caps |= NFS_CAP_SYMLINKS;
        if (res.attr_bitmask[0] & FATTR4_WORD0_FILEID)
            server->caps |= NFS_CAP_FILEID;
        if (res.attr_bitmask[1] & FATTR4_WORD1_MODE)
            server->caps |= NFS_CAP_MODE;
        if (res.attr_bitmask[1] & FATTR4_WORD1_NUMLINKS)
            server->caps |= NFS_CAP_NLINK;
        if (res.attr_bitmask[1] & FATTR4_WORD1_OWNER)
            server->caps |= NFS_CAP_OWNER;
        if (res.attr_bitmask[1] & FATTR4_WORD1_OWNER_GROUP)
            server->caps |= NFS_CAP_OWNER_GROUP;
        if (res.attr_bitmask[1] & FATTR4_WORD1_TIME_ACCESS)
            server->caps |= NFS_CAP_ATIME;
        if (res.attr_bitmask[1] & FATTR4_WORD1_TIME_METADATA)
            server->caps |= NFS_CAP_CTIME;
        if (res.attr_bitmask[1] & FATTR4_WORD1_TIME_MODIFY)
            server->caps |= NFS_CAP_MTIME;

        memcpy(server->cache_consistency_bitmask, res.attr_bitmask, sizeof(server->cache_consistency_bitmask));
        server->cache_consistency_bitmask[0] &= FATTR4_WORD0_CHANGE|FATTR4_WORD0_SIZE;
        server->cache_consistency_bitmask[1] &= FATTR4_WORD1_TIME_METADATA|FATTR4_WORD1_TIME_MODIFY;
        server->acl_bitmask = res.acl_bitmask;
        server->fh_expire_type = res.fh_expire_type;
    }

    return status;
}

int nfs4_server_capabilities(struct nfs_server *server, struct nfs_fh *fhandle)
{
    struct nfs4_exception exception = { };
    int err;
    do {
        err = nfs4_handle_exception(server,
                _nfs4_server_capabilities(server, fhandle),
                &exception);
    } while (exception.retry);
    return err;
}

static int _nfs4_lookup_root(struct nfs_server *server, struct nfs_fh *fhandle,
        struct nfs_fsinfo *info)
{
    struct nfs4_lookup_root_arg args = {
        .bitmask = nfs4_fattr_bitmap,
    };
    struct nfs4_lookup_res res = {
        .server = server,
        .fattr = info->fattr,
        .fh = fhandle,
    };
    struct rpc_message msg = {
        .rpc_proc = &nfs4_procedures[NFSPROC4_CLNT_LOOKUP_ROOT],
        .rpc_argp = &args,
        .rpc_resp = &res,
    };

    nfs_fattr_init(info->fattr);
    return nfs4_call_sync(server->client, server, &msg, &args.seq_args, &res.seq_res, 0);
}

static int nfs4_lookup_root(struct nfs_server *server, struct nfs_fh *fhandle,
        struct nfs_fsinfo *info)
{
    struct nfs4_exception exception = { };
    int err;
    do {
        err = _nfs4_lookup_root(server, fhandle, info);
        switch (err) {
        case 0:
        case -NFS4ERR_WRONGSEC:
            goto out;
        default:
            err = nfs4_handle_exception(server, err, &exception);
        }
    } while (exception.retry);
out:
    return err;
}

static int nfs4_lookup_root_sec(struct nfs_server *server, struct nfs_fh *fhandle,
                struct nfs_fsinfo *info, rpc_authflavor_t flavor)
{
    struct rpc_auth *auth;
    int ret;

    auth = rpcauth_create(flavor, server->client);
    if (IS_ERR(auth)) {
        ret = -EIO;
        goto out;
    }
    ret = nfs4_lookup_root(server, fhandle, info);
out:
    return ret;
}

static int nfs4_find_root_sec(struct nfs_server *server, struct nfs_fh *fhandle,
                  struct nfs_fsinfo *info)
{
    int i, len, status = 0;
    rpc_authflavor_t flav_array[NFS_MAX_SECFLAVORS];

    len = rpcauth_list_flavors(flav_array, ARRAY_SIZE(flav_array));
    BUG_ON(len < 0);

    for (i = 0; i < len; i++) {
        /* AUTH_UNIX is the default flavor if none was specified,
         * thus has already been tried. */
        if (flav_array[i] == RPC_AUTH_UNIX)
            continue;

        status = nfs4_lookup_root_sec(server, fhandle, info, flav_array[i]);
        if (status == -NFS4ERR_WRONGSEC || status == -EACCES)
            continue;
        break;
    }
    /*
     * -EACCESS could mean that the user doesn't have correct permissions
     * to access the mount.  It could also mean that we tried to mount
     * with a gss auth flavor, but rpc.gssd isn't running.  Either way,
     * existing mount programs don't handle -EACCES very well so it should
     * be mapped to -EPERM instead.
     */
    if (status == -EACCES)
        status = -EPERM;
    return status;
}

/*
 * get the file handle for the "/" directory on the server
 */
int nfs4_proc_get_rootfh(struct nfs_server *server, struct nfs_fh *fhandle,
             struct nfs_fsinfo *info)
{
    int minor_version = server->nfs_client->cl_minorversion;
    int status = nfs4_lookup_root(server, fhandle, info);
    if ((status == -NFS4ERR_WRONGSEC) && !(server->flags & NFS_MOUNT_SECFLAVOUR))
        /*
         * A status of -NFS4ERR_WRONGSEC will be mapped to -EPERM
         * by nfs4_map_errors() as this function exits.
         */
        status = nfs_v4_minor_ops[minor_version]->find_root_sec(server, fhandle, info);
    if (status == 0)
        status = nfs4_server_capabilities(server, fhandle);
    if (status == 0)
        status = nfs4_do_fsinfo(server, fhandle, info);
    return nfs4_map_errors(status);
}

static int nfs4_proc_get_root(struct nfs_server *server, struct nfs_fh *mntfh,
                  struct nfs_fsinfo *info)
{
    int error;
    struct nfs_fattr *fattr = info->fattr;

    error = nfs4_server_capabilities(server, mntfh);
    if (error < 0) {
        dprintk("nfs4_get_root: getcaps error = %d\n", -error);
        return error;
    }

    error = nfs4_proc_getattr(server, mntfh, fattr);
    if (error < 0) {
        dprintk("nfs4_get_root: getattr error = %d\n", -error);
        return error;
    }

    if (fattr->valid & NFS_ATTR_FATTR_FSID &&
        !nfs_fsid_equal(&server->fsid, &fattr->fsid))
        memcpy(&server->fsid, &fattr->fsid, sizeof(server->fsid));

    return error;
}

/*
 * Get locations and (maybe) other attributes of a referral.
 * Note that we'll actually follow the referral later when
 * we detect fsid mismatch in inode revalidation
 */
static int nfs4_get_referral(struct rpc_clnt *client, struct inode *dir,
                 const struct qstr *name, struct nfs_fattr *fattr,
                 struct nfs_fh *fhandle)
{
    int status = -ENOMEM;
    struct page *page = NULL;
    struct nfs4_fs_locations *locations = NULL;

    page = alloc_page(GFP_KERNEL);
    if (page == NULL)
        goto out;
    locations = kmalloc(sizeof(struct nfs4_fs_locations), GFP_KERNEL);
    if (locations == NULL)
        goto out;

    status = nfs4_proc_fs_locations(client, dir, name, locations, page);
    if (status != 0)
        goto out;
    /* Make sure server returned a different fsid for the referral */
    if (nfs_fsid_equal(&NFS_SERVER(dir)->fsid, &locations->fattr.fsid)) {
        dprintk("%s: server did not return a different fsid for"
            " a referral at %s\n", __func__, name->name);
        status = -EIO;
        goto out;
    }
    /* Fixup attributes for the nfs_lookup() call to nfs_fhget() */
    nfs_fixup_referral_attributes(&locations->fattr);

    /* replace the lookup nfs_fattr with the locations nfs_fattr */
    memcpy(fattr, &locations->fattr, sizeof(struct nfs_fattr));
    memset(fhandle, 0, sizeof(struct nfs_fh));
out:
    if (page)
        __free_page(page);
    kfree(locations);
    return status;
}

static int _nfs4_proc_getattr(struct nfs_server *server, struct nfs_fh *fhandle, struct nfs_fattr *fattr)
{
    struct nfs4_getattr_arg args = {
        .fh = fhandle,
        .bitmask = server->attr_bitmask,
    };
    struct nfs4_getattr_res res = {
        .fattr = fattr,
        .server = server,
    };
    struct rpc_message msg = {
        .rpc_proc = &nfs4_procedures[NFSPROC4_CLNT_GETATTR],
        .rpc_argp = &args,
        .rpc_resp = &res,
    };
    
    nfs_fattr_init(fattr);
    return nfs4_call_sync(server->client, server, &msg, &args.seq_args, &res.seq_res, 0);
}

static int nfs4_proc_getattr(struct nfs_server *server, struct nfs_fh *fhandle, struct nfs_fattr *fattr)
{
    struct nfs4_exception exception = { };
    int err;
    do {
        err = nfs4_handle_exception(server,
                _nfs4_proc_getattr(server, fhandle, fattr),
                &exception);
    } while (exception.retry);
    return err;
}

/* 
 * The file is not closed if it is opened due to the a request to change
 * the size of the file. The open call will not be needed once the
 * VFS layer lookup-intents are implemented.
 *
 * Close is called when the inode is destroyed.
 * If we haven't opened the file for O_WRONLY, we
 * need to in the size_change case to obtain a stateid.
 *
 * Got race?
 * Because OPEN is always done by name in nfsv4, it is
 * possible that we opened a different file by the same
 * name.  We can recognize this race condition, but we
 * can't do anything about it besides returning an error.
 *
 * This will be fixed with VFS changes (lookup-intent).
 */
static int
nfs4_proc_setattr(struct dentry *dentry, struct nfs_fattr *fattr,
          struct iattr *sattr)
{
    struct inode *inode = dentry->d_inode;
    struct rpc_cred *cred = NULL;
    struct nfs4_state *state = NULL;
    int status;

    if (pnfs_ld_layoutret_on_setattr(inode))
        pnfs_return_layout(inode);

    nfs_fattr_init(fattr);
    
    /* Deal with open(O_TRUNC) */
    if (sattr->ia_valid & ATTR_OPEN)
        sattr->ia_valid &= ~(ATTR_MTIME|ATTR_CTIME|ATTR_OPEN);

    /* Optimization: if the end result is no change, don't RPC */
    if ((sattr->ia_valid & ~(ATTR_FILE)) == 0)
        return 0;

    /* Search for an existing open(O_WRITE) file */
    if (sattr->ia_valid & ATTR_FILE) {
        struct nfs_open_context *ctx;

        ctx = nfs_file_open_context(sattr->ia_file);
        if (ctx) {
            cred = ctx->cred;
            state = ctx->state;
        }
    }

    status = nfs4_do_setattr(inode, cred, fattr, sattr, state);
    if (status == 0)
        nfs_setattr_update_inode(inode, sattr);
    return status;
}

static int _nfs4_proc_lookup(struct rpc_clnt *clnt, struct inode *dir,
        const struct qstr *name, struct nfs_fh *fhandle,
        struct nfs_fattr *fattr)
{
    struct nfs_server *server = NFS_SERVER(dir);
    int            status;
    struct nfs4_lookup_arg args = {
        .bitmask = server->attr_bitmask,
        .dir_fh = NFS_FH(dir),
        .name = name,
    };
    struct nfs4_lookup_res res = {
        .server = server,
        .fattr = fattr,
        .fh = fhandle,
    };
    struct rpc_message msg = {
        .rpc_proc = &nfs4_procedures[NFSPROC4_CLNT_LOOKUP],
        .rpc_argp = &args,
        .rpc_resp = &res,
    };

    nfs_fattr_init(fattr);

    dprintk("NFS call  lookup %s\n", name->name);
    status = nfs4_call_sync(clnt, server, &msg, &args.seq_args, &res.seq_res, 0);
    dprintk("NFS reply lookup: %d\n", status);
    return status;
}

static void nfs_fixup_secinfo_attributes(struct nfs_fattr *fattr)
{
    fattr->valid |= NFS_ATTR_FATTR_TYPE | NFS_ATTR_FATTR_MODE |
        NFS_ATTR_FATTR_NLINK | NFS_ATTR_FATTR_MOUNTPOINT;
    fattr->mode = S_IFDIR | S_IRUGO | S_IXUGO;
    fattr->nlink = 2;
}

static int nfs4_proc_lookup_common(struct rpc_clnt **clnt, struct inode *dir,
                   struct qstr *name, struct nfs_fh *fhandle,
                   struct nfs_fattr *fattr)
{
    struct nfs4_exception exception = { };
    struct rpc_clnt *client = *clnt;
    int err;
    do {
        err = _nfs4_proc_lookup(client, dir, name, fhandle, fattr);
        switch (err) {
        case -NFS4ERR_BADNAME:
            err = -ENOENT;
            goto out;
        case -NFS4ERR_MOVED:
            err = nfs4_get_referral(client, dir, name, fattr, fhandle);
            goto out;
        case -NFS4ERR_WRONGSEC:
            err = -EPERM;
            if (client != *clnt)
                goto out;

            client = nfs4_create_sec_client(client, dir, name);
            if (IS_ERR(client))
                return PTR_ERR(client);

            exception.retry = 1;
            break;
        default:
            err = nfs4_handle_exception(NFS_SERVER(dir), err, &exception);
        }
    } while (exception.retry);

out:
    if (err == 0)
        *clnt = client;
    else if (client != *clnt)
        rpc_shutdown_client(client);

    return err;
}

static int nfs4_proc_lookup(struct inode *dir, struct qstr *name,
                struct nfs_fh *fhandle, struct nfs_fattr *fattr)
{
    int status;
    struct rpc_clnt *client = NFS_CLIENT(dir);

    status = nfs4_proc_lookup_common(&client, dir, name, fhandle, fattr);
    if (client != NFS_CLIENT(dir)) {
        rpc_shutdown_client(client);
        nfs_fixup_secinfo_attributes(fattr);
    }
    return status;
}

struct rpc_clnt *
nfs4_proc_lookup_mountpoint(struct inode *dir, struct qstr *name,
                struct nfs_fh *fhandle, struct nfs_fattr *fattr)
{
    int status;
    struct rpc_clnt *client = rpc_clone_client(NFS_CLIENT(dir));

    status = nfs4_proc_lookup_common(&client, dir, name, fhandle, fattr);
    if (status < 0) {
        rpc_shutdown_client(client);
        return ERR_PTR(status);
    }
    return client;
}

static int _nfs4_proc_access(struct inode *inode, struct nfs_access_entry *entry)
{
    struct nfs_server *server = NFS_SERVER(inode);
    struct nfs4_accessargs args = {
        .fh = NFS_FH(inode),
        .bitmask = server->cache_consistency_bitmask,
    };
    struct nfs4_accessres res = {
        .server = server,
    };
    struct rpc_message msg = {
        .rpc_proc = &nfs4_procedures[NFSPROC4_CLNT_ACCESS],
        .rpc_argp = &args,
        .rpc_resp = &res,
        .rpc_cred = entry->cred,
    };
    int mode = entry->mask;
    int status;

    /*
     * Determine which access bits we want to ask for...
     */
    if (mode & MAY_READ)
        args.access |= NFS4_ACCESS_READ;
    if (S_ISDIR(inode->i_mode)) {
        if (mode & MAY_WRITE)
            args.access |= NFS4_ACCESS_MODIFY | NFS4_ACCESS_EXTEND | NFS4_ACCESS_DELETE;
        if (mode & MAY_EXEC)
            args.access |= NFS4_ACCESS_LOOKUP;
    } else {
        if (mode & MAY_WRITE)
            args.access |= NFS4_ACCESS_MODIFY | NFS4_ACCESS_EXTEND;
        if (mode & MAY_EXEC)
            args.access |= NFS4_ACCESS_EXECUTE;
    }

    res.fattr = nfs_alloc_fattr();
    if (res.fattr == NULL)
        return -ENOMEM;

    status = nfs4_call_sync(server->client, server, &msg, &args.seq_args, &res.seq_res, 0);
    if (!status) {
        nfs_access_set_mask(entry, res.access);
        nfs_refresh_inode(inode, res.fattr);
    }
    nfs_free_fattr(res.fattr);
    return status;
}

static int nfs4_proc_access(struct inode *inode, struct nfs_access_entry *entry)
{
    struct nfs4_exception exception = { };
    int err;
    do {
        err = nfs4_handle_exception(NFS_SERVER(inode),
                _nfs4_proc_access(inode, entry),
                &exception);
    } while (exception.retry);
    return err;
}

/*
 * TODO: For the time being, we don't try to get any attributes
 * along with any of the zero-copy operations READ, READDIR,
 * READLINK, WRITE.
 *
 * In the case of the first three, we want to put the GETATTR
 * after the read-type operation -- this is because it is hard
 * to predict the length of a GETATTR response in v4, and thus
 * align the READ data correctly.  This means that the GETATTR
 * may end up partially falling into the page cache, and we should
 * shift it into the 'tail' of the xdr_buf before processing.
 * To do this efficiently, we need to know the total length
 * of data received, which doesn't seem to be available outside
 * of the RPC layer.
 *
 * In the case of WRITE, we also want to put the GETATTR after
 * the operation -- in this case because we want to make sure
 * we get the post-operation mtime and size.
 *
 * Both of these changes to the XDR layer would in fact be quite
 * minor, but I decided to leave them for a subsequent patch.
 */
static int _nfs4_proc_readlink(struct inode *inode, struct page *page,
        unsigned int pgbase, unsigned int pglen)
{
    struct nfs4_readlink args = {
        .fh       = NFS_FH(inode),
        .pgbase   = pgbase,
        .pglen    = pglen,
        .pages    = &page,
    };
    struct nfs4_readlink_res res;
    struct rpc_message msg = {
        .rpc_proc = &nfs4_procedures[NFSPROC4_CLNT_READLINK],
        .rpc_argp = &args,
        .rpc_resp = &res,
    };

    return nfs4_call_sync(NFS_SERVER(inode)->client, NFS_SERVER(inode), &msg, &args.seq_args, &res.seq_res, 0);
}

static int nfs4_proc_readlink(struct inode *inode, struct page *page,
        unsigned int pgbase, unsigned int pglen)
{
    struct nfs4_exception exception = { };
    int err;
    do {
        err = nfs4_handle_exception(NFS_SERVER(inode),
                _nfs4_proc_readlink(inode, page, pgbase, pglen),
                &exception);
    } while (exception.retry);
    return err;
}

/*
 * This is just for mknod.  open(O_CREAT) will always do ->open_context().
 */
static int
nfs4_proc_create(struct inode *dir, struct dentry *dentry, struct iattr *sattr,
         int flags)
{
    struct nfs_open_context *ctx;
    struct nfs4_state *state;
    int status = 0;

    ctx = alloc_nfs_open_context(dentry, FMODE_READ);
    if (IS_ERR(ctx))
        return PTR_ERR(ctx);

    sattr->ia_mode &= ~current_umask();
    state = nfs4_do_open(dir, dentry, ctx->mode,
            flags, sattr, ctx->cred,
            &ctx->mdsthreshold);
    d_drop(dentry);
    if (IS_ERR(state)) {
        status = PTR_ERR(state);
        goto out;
    }
    d_add(dentry, igrab(state->inode));
    nfs_set_verifier(dentry, nfs_save_change_attribute(dir));
    ctx->state = state;
out:
    put_nfs_open_context(ctx);
    return status;
}

static int _nfs4_proc_remove(struct inode *dir, struct qstr *name)
{
    struct nfs_server *server = NFS_SERVER(dir);
    struct nfs_removeargs args = {
        .fh = NFS_FH(dir),
        .name = *name,
    };
    struct nfs_removeres res = {
        .server = server,
    };
    struct rpc_message msg = {
        .rpc_proc = &nfs4_procedures[NFSPROC4_CLNT_REMOVE],
        .rpc_argp = &args,
        .rpc_resp = &res,
    };
    int status;

    status = nfs4_call_sync(server->client, server, &msg, &args.seq_args, &res.seq_res, 1);
    if (status == 0)
        update_changeattr(dir, &res.cinfo);
    return status;
}

static int nfs4_proc_remove(struct inode *dir, struct qstr *name)
{
    struct nfs4_exception exception = { };
    int err;
    do {
        err = nfs4_handle_exception(NFS_SERVER(dir),
                _nfs4_proc_remove(dir, name),
                &exception);
    } while (exception.retry);
    return err;
}

static void nfs4_proc_unlink_setup(struct rpc_message *msg, struct inode *dir)
{
    struct nfs_server *server = NFS_SERVER(dir);
    struct nfs_removeargs *args = msg->rpc_argp;
    struct nfs_removeres *res = msg->rpc_resp;

    res->server = server;
    msg->rpc_proc = &nfs4_procedures[NFSPROC4_CLNT_REMOVE];
    nfs41_init_sequence(&args->seq_args, &res->seq_res, 1);
}

static void nfs4_proc_unlink_rpc_prepare(struct rpc_task *task, struct nfs_unlinkdata *data)
{
    if (nfs4_setup_sequence(NFS_SERVER(data->dir),
                &data->args.seq_args,
                &data->res.seq_res,
                task))
        return;
    rpc_call_start(task);
}

static int nfs4_proc_unlink_done(struct rpc_task *task, struct inode *dir)
{
    struct nfs_removeres *res = task->tk_msg.rpc_resp;

    if (!nfs4_sequence_done(task, &res->seq_res))
        return 0;
    if (nfs4_async_handle_error(task, res->server, NULL) == -EAGAIN)
        return 0;
    update_changeattr(dir, &res->cinfo);
    return 1;
}

static void nfs4_proc_rename_setup(struct rpc_message *msg, struct inode *dir)
{
    struct nfs_server *server = NFS_SERVER(dir);
    struct nfs_renameargs *arg = msg->rpc_argp;
    struct nfs_renameres *res = msg->rpc_resp;

    msg->rpc_proc = &nfs4_procedures[NFSPROC4_CLNT_RENAME];
    res->server = server;
    nfs41_init_sequence(&arg->seq_args, &res->seq_res, 1);
}

static void nfs4_proc_rename_rpc_prepare(struct rpc_task *task, struct nfs_renamedata *data)
{
    if (nfs4_setup_sequence(NFS_SERVER(data->old_dir),
                &data->args.seq_args,
                &data->res.seq_res,
                task))
        return;
    rpc_call_start(task);
}

static int nfs4_proc_rename_done(struct rpc_task *task, struct inode *old_dir,
                 struct inode *new_dir)
{
    struct nfs_renameres *res = task->tk_msg.rpc_resp;

    if (!nfs4_sequence_done(task, &res->seq_res))
        return 0;
    if (nfs4_async_handle_error(task, res->server, NULL) == -EAGAIN)
        return 0;

    update_changeattr(old_dir, &res->old_cinfo);
    update_changeattr(new_dir, &res->new_cinfo);
    return 1;
}

static int _nfs4_proc_rename(struct inode *old_dir, struct qstr *old_name,
        struct inode *new_dir, struct qstr *new_name)
{
    struct nfs_server *server = NFS_SERVER(old_dir);
    struct nfs_renameargs arg = {
        .old_dir = NFS_FH(old_dir),
        .new_dir = NFS_FH(new_dir),
        .old_name = old_name,
        .new_name = new_name,
    };
    struct nfs_renameres res = {
        .server = server,
    };
    struct rpc_message msg = {
        .rpc_proc = &nfs4_procedures[NFSPROC4_CLNT_RENAME],
        .rpc_argp = &arg,
        .rpc_resp = &res,
    };
    int status = -ENOMEM;
    
    status = nfs4_call_sync(server->client, server, &msg, &arg.seq_args, &res.seq_res, 1);
    if (!status) {
        update_changeattr(old_dir, &res.old_cinfo);
        update_changeattr(new_dir, &res.new_cinfo);
    }
    return status;
}

static int nfs4_proc_rename(struct inode *old_dir, struct qstr *old_name,
        struct inode *new_dir, struct qstr *new_name)
{
    struct nfs4_exception exception = { };
    int err;
    do {
        err = nfs4_handle_exception(NFS_SERVER(old_dir),
                _nfs4_proc_rename(old_dir, old_name,
                    new_dir, new_name),
                &exception);
    } while (exception.retry);
    return err;
}

static int _nfs4_proc_link(struct inode *inode, struct inode *dir, struct qstr *name)
{
    struct nfs_server *server = NFS_SERVER(inode);
    struct nfs4_link_arg arg = {
        .fh     = NFS_FH(inode),
        .dir_fh = NFS_FH(dir),
        .name   = name,
        .bitmask = server->attr_bitmask,
    };
    struct nfs4_link_res res = {
        .server = server,
    };
    struct rpc_message msg = {
        .rpc_proc = &nfs4_procedures[NFSPROC4_CLNT_LINK],
        .rpc_argp = &arg,
        .rpc_resp = &res,
    };
    int status = -ENOMEM;

    res.fattr = nfs_alloc_fattr();
    if (res.fattr == NULL)
        goto out;

    status = nfs4_call_sync(server->client, server, &msg, &arg.seq_args, &res.seq_res, 1);
    if (!status) {
        update_changeattr(dir, &res.cinfo);
        nfs_post_op_update_inode(inode, res.fattr);
    }
out:
    nfs_free_fattr(res.fattr);
    return status;
}

static int nfs4_proc_link(struct inode *inode, struct inode *dir, struct qstr *name)
{
    struct nfs4_exception exception = { };
    int err;
    do {
        err = nfs4_handle_exception(NFS_SERVER(inode),
                _nfs4_proc_link(inode, dir, name),
                &exception);
    } while (exception.retry);
    return err;
}

struct nfs4_createdata {
    struct rpc_message msg;
    struct nfs4_create_arg arg;
    struct nfs4_create_res res;
    struct nfs_fh fh;
    struct nfs_fattr fattr;
};

static struct nfs4_createdata *nfs4_alloc_createdata(struct inode *dir,
        struct qstr *name, struct iattr *sattr, u32 ftype)
{
    struct nfs4_createdata *data;

    data = kzalloc(sizeof(*data), GFP_KERNEL);
    if (data != NULL) {
        struct nfs_server *server = NFS_SERVER(dir);

        data->msg.rpc_proc = &nfs4_procedures[NFSPROC4_CLNT_CREATE];
        data->msg.rpc_argp = &data->arg;
        data->msg.rpc_resp = &data->res;
        data->arg.dir_fh = NFS_FH(dir);
        data->arg.server = server;
        data->arg.name = name;
        data->arg.attrs = sattr;
        data->arg.ftype = ftype;
        data->arg.bitmask = server->attr_bitmask;
        data->res.server = server;
        data->res.fh = &data->fh;
        data->res.fattr = &data->fattr;
        nfs_fattr_init(data->res.fattr);
    }
    return data;
}

static int nfs4_do_create(struct inode *dir, struct dentry *dentry, struct nfs4_createdata *data)
{
    int status = nfs4_call_sync(NFS_SERVER(dir)->client, NFS_SERVER(dir), &data->msg,
                    &data->arg.seq_args, &data->res.seq_res, 1);
    if (status == 0) {
        update_changeattr(dir, &data->res.dir_cinfo);
        status = nfs_instantiate(dentry, data->res.fh, data->res.fattr);
    }
    return status;
}

static void nfs4_free_createdata(struct nfs4_createdata *data)
{
    kfree(data);
}

static int _nfs4_proc_symlink(struct inode *dir, struct dentry *dentry,
        struct page *page, unsigned int len, struct iattr *sattr)
{
    struct nfs4_createdata *data;
    int status = -ENAMETOOLONG;

    if (len > NFS4_MAXPATHLEN)
        goto out;

    status = -ENOMEM;
    data = nfs4_alloc_createdata(dir, &dentry->d_name, sattr, NF4LNK);
    if (data == NULL)
        goto out;

    data->msg.rpc_proc = &nfs4_procedures[NFSPROC4_CLNT_SYMLINK];
    data->arg.u.symlink.pages = &page;
    data->arg.u.symlink.len = len;
    
    status = nfs4_do_create(dir, dentry, data);

    nfs4_free_createdata(data);
out:
    return status;
}

static int nfs4_proc_symlink(struct inode *dir, struct dentry *dentry,
        struct page *page, unsigned int len, struct iattr *sattr)
{
    struct nfs4_exception exception = { };
    int err;
    do {
        err = nfs4_handle_exception(NFS_SERVER(dir),
                _nfs4_proc_symlink(dir, dentry, page,
                            len, sattr),
                &exception);
    } while (exception.retry);
    return err;
}

static int _nfs4_proc_mkdir(struct inode *dir, struct dentry *dentry,
        struct iattr *sattr)
{
    struct nfs4_createdata *data;
    int status = -ENOMEM;

    data = nfs4_alloc_createdata(dir, &dentry->d_name, sattr, NF4DIR);
    if (data == NULL)
        goto out;

    status = nfs4_do_create(dir, dentry, data);

    nfs4_free_createdata(data);
out:
    return status;
}

static int nfs4_proc_mkdir(struct inode *dir, struct dentry *dentry,
        struct iattr *sattr)
{
    struct nfs4_exception exception = { };
    int err;

    sattr->ia_mode &= ~current_umask();
    do {
        err = nfs4_handle_exception(NFS_SERVER(dir),
                _nfs4_proc_mkdir(dir, dentry, sattr),
                &exception);
    } while (exception.retry);
    return err;
}

static int _nfs4_proc_readdir(struct dentry *dentry, struct rpc_cred *cred,
        u64 cookie, struct page **pages, unsigned int count, int plus)
{
    struct inode        *dir = dentry->d_inode;
    struct nfs4_readdir_arg args = {
        .fh = NFS_FH(dir),
        .pages = pages,
        .pgbase = 0,
        .count = count,
        .bitmask = NFS_SERVER(dentry->d_inode)->attr_bitmask,
        .plus = plus,
    };
    struct nfs4_readdir_res res;
    struct rpc_message msg = {
        .rpc_proc = &nfs4_procedures[NFSPROC4_CLNT_READDIR],
        .rpc_argp = &args,
        .rpc_resp = &res,
        .rpc_cred = cred,
    };
    int         status;

    dprintk("%s: dentry = %s/%s, cookie = %Lu\n", __func__,
            dentry->d_parent->d_name.name,
            dentry->d_name.name,
            (unsigned long long)cookie);
    nfs4_setup_readdir(cookie, NFS_I(dir)->cookieverf, dentry, &args);
    res.pgbase = args.pgbase;
    status = nfs4_call_sync(NFS_SERVER(dir)->client, NFS_SERVER(dir), &msg, &args.seq_args, &res.seq_res, 0);
    if (status >= 0) {
        memcpy(NFS_I(dir)->cookieverf, res.verifier.data, NFS4_VERIFIER_SIZE);
        status += args.pgbase;
    }

    nfs_invalidate_atime(dir);

    dprintk("%s: returns %d\n", __func__, status);
    return status;
}

static int nfs4_proc_readdir(struct dentry *dentry, struct rpc_cred *cred,
        u64 cookie, struct page **pages, unsigned int count, int plus)
{
    struct nfs4_exception exception = { };
    int err;
    do {
        err = nfs4_handle_exception(NFS_SERVER(dentry->d_inode),
                _nfs4_proc_readdir(dentry, cred, cookie,
                    pages, count, plus),
                &exception);
    } while (exception.retry);
    return err;
}

static int _nfs4_proc_mknod(struct inode *dir, struct dentry *dentry,
        struct iattr *sattr, dev_t rdev)
{
    struct nfs4_createdata *data;
    int mode = sattr->ia_mode;
    int status = -ENOMEM;

    BUG_ON(!(sattr->ia_valid & ATTR_MODE));
    BUG_ON(!S_ISFIFO(mode) && !S_ISBLK(mode) && !S_ISCHR(mode) && !S_ISSOCK(mode));

    data = nfs4_alloc_createdata(dir, &dentry->d_name, sattr, NF4SOCK);
    if (data == NULL)
        goto out;

    if (S_ISFIFO(mode))
        data->arg.ftype = NF4FIFO;
    else if (S_ISBLK(mode)) {
        data->arg.ftype = NF4BLK;
        data->arg.u.device.specdata1 = MAJOR(rdev);
        data->arg.u.device.specdata2 = MINOR(rdev);
    }
    else if (S_ISCHR(mode)) {
        data->arg.ftype = NF4CHR;
        data->arg.u.device.specdata1 = MAJOR(rdev);
        data->arg.u.device.specdata2 = MINOR(rdev);
    }
    
    status = nfs4_do_create(dir, dentry, data);

    nfs4_free_createdata(data);
out:
    return status;
}

static int nfs4_proc_mknod(struct inode *dir, struct dentry *dentry,
        struct iattr *sattr, dev_t rdev)
{
    struct nfs4_exception exception = { };
    int err;

    sattr->ia_mode &= ~current_umask();
    do {
        err = nfs4_handle_exception(NFS_SERVER(dir),
                _nfs4_proc_mknod(dir, dentry, sattr, rdev),
                &exception);
    } while (exception.retry);
    return err;
}

static int _nfs4_proc_statfs(struct nfs_server *server, struct nfs_fh *fhandle,
         struct nfs_fsstat *fsstat)
{
    struct nfs4_statfs_arg args = {
        .fh = fhandle,
        .bitmask = server->attr_bitmask,
    };
    struct nfs4_statfs_res res = {
        .fsstat = fsstat,
    };
    struct rpc_message msg = {
        .rpc_proc = &nfs4_procedures[NFSPROC4_CLNT_STATFS],
        .rpc_argp = &args,
        .rpc_resp = &res,
    };

    nfs_fattr_init(fsstat->fattr);
    return  nfs4_call_sync(server->client, server, &msg, &args.seq_args, &res.seq_res, 0);
}

static int nfs4_proc_statfs(struct nfs_server *server, struct nfs_fh *fhandle, struct nfs_fsstat *fsstat)
{
    struct nfs4_exception exception = { };
    int err;
    do {
        err = nfs4_handle_exception(server,
                _nfs4_proc_statfs(server, fhandle, fsstat),
                &exception);
    } while (exception.retry);
    return err;
}

static int _nfs4_do_fsinfo(struct nfs_server *server, struct nfs_fh *fhandle,
        struct nfs_fsinfo *fsinfo)
{
    struct nfs4_fsinfo_arg args = {
        .fh = fhandle,
        .bitmask = server->attr_bitmask,
    };
    struct nfs4_fsinfo_res res = {
        .fsinfo = fsinfo,
    };
    struct rpc_message msg = {
        .rpc_proc = &nfs4_procedures[NFSPROC4_CLNT_FSINFO],
        .rpc_argp = &args,
        .rpc_resp = &res,
    };

    return nfs4_call_sync(server->client, server, &msg, &args.seq_args, &res.seq_res, 0);
}

static int nfs4_do_fsinfo(struct nfs_server *server, struct nfs_fh *fhandle, struct nfs_fsinfo *fsinfo)
{
    struct nfs4_exception exception = { };
    int err;

    do {
        err = nfs4_handle_exception(server,
                _nfs4_do_fsinfo(server, fhandle, fsinfo),
                &exception);
    } while (exception.retry);
    return err;
}

static int nfs4_proc_fsinfo(struct nfs_server *server, struct nfs_fh *fhandle, struct nfs_fsinfo *fsinfo)
{
    int error;

    nfs_fattr_init(fsinfo->fattr);
    error = nfs4_do_fsinfo(server, fhandle, fsinfo);
    if (error == 0) {
        /* block layout checks this! */
        server->pnfs_blksize = fsinfo->blksize;
        set_pnfs_layoutdriver(server, fhandle, fsinfo->layouttype);
    }

    return error;
}

static int _nfs4_proc_pathconf(struct nfs_server *server, struct nfs_fh *fhandle,
        struct nfs_pathconf *pathconf)
{
    struct nfs4_pathconf_arg args = {
        .fh = fhandle,
        .bitmask = server->attr_bitmask,
    };
    struct nfs4_pathconf_res res = {
        .pathconf = pathconf,
    };
    struct rpc_message msg = {
        .rpc_proc = &nfs4_procedures[NFSPROC4_CLNT_PATHCONF],
        .rpc_argp = &args,
        .rpc_resp = &res,
    };

    /* None of the pathconf attributes are mandatory to implement */
    if ((args.bitmask[0] & nfs4_pathconf_bitmap[0]) == 0) {
        memset(pathconf, 0, sizeof(*pathconf));
        return 0;
    }

    nfs_fattr_init(pathconf->fattr);
    return nfs4_call_sync(server->client, server, &msg, &args.seq_args, &res.seq_res, 0);
}

static int nfs4_proc_pathconf(struct nfs_server *server, struct nfs_fh *fhandle,
        struct nfs_pathconf *pathconf)
{
    struct nfs4_exception exception = { };
    int err;

    do {
        err = nfs4_handle_exception(server,
                _nfs4_proc_pathconf(server, fhandle, pathconf),
                &exception);
    } while (exception.retry);
    return err;
}

void __nfs4_read_done_cb(struct nfs_read_data *data)
{
    nfs_invalidate_atime(data->header->inode);
}

static int nfs4_read_done_cb(struct rpc_task *task, struct nfs_read_data *data)
{
    struct nfs_server *server = NFS_SERVER(data->header->inode);

    if (nfs4_async_handle_error(task, server, data->args.context->state) == -EAGAIN) {
        rpc_restart_call_prepare(task);
        return -EAGAIN;
    }

    __nfs4_read_done_cb(data);
    if (task->tk_status > 0)
        renew_lease(server, data->timestamp);
    return 0;
}

static int nfs4_read_done(struct rpc_task *task, struct nfs_read_data *data)
{

    dprintk("--> %s\n", __func__);

    if (!nfs4_sequence_done(task, &data->res.seq_res))
        return -EAGAIN;

    return data->read_done_cb ? data->read_done_cb(task, data) :
                    nfs4_read_done_cb(task, data);
}

static void nfs4_proc_read_setup(struct nfs_read_data *data, struct rpc_message *msg)
{
    data->timestamp   = jiffies;
    data->read_done_cb = nfs4_read_done_cb;
    msg->rpc_proc = &nfs4_procedures[NFSPROC4_CLNT_READ];
    nfs41_init_sequence(&data->args.seq_args, &data->res.seq_res, 0);
}

static void nfs4_proc_read_rpc_prepare(struct rpc_task *task, struct nfs_read_data *data)
{
    if (nfs4_setup_sequence(NFS_SERVER(data->header->inode),
                &data->args.seq_args,
                &data->res.seq_res,
                task))
        return;
    rpc_call_start(task);
}

static int nfs4_write_done_cb(struct rpc_task *task, struct nfs_write_data *data)
{
    struct inode *inode = data->header->inode;
    
    if (nfs4_async_handle_error(task, NFS_SERVER(inode), data->args.context->state) == -EAGAIN) {
        rpc_restart_call_prepare(task);
        return -EAGAIN;
    }
    if (task->tk_status >= 0) {
        renew_lease(NFS_SERVER(inode), data->timestamp);
        nfs_post_op_update_inode_force_wcc(inode, &data->fattr);
    }
    return 0;
}

static int nfs4_write_done(struct rpc_task *task, struct nfs_write_data *data)
{
    if (!nfs4_sequence_done(task, &data->res.seq_res))
        return -EAGAIN;
    return data->write_done_cb ? data->write_done_cb(task, data) :
        nfs4_write_done_cb(task, data);
}

static
bool nfs4_write_need_cache_consistency_data(const struct nfs_write_data *data)
{
    const struct nfs_pgio_header *hdr = data->header;

    /* Don't request attributes for pNFS or O_DIRECT writes */
    if (data->ds_clp != NULL || hdr->dreq != NULL)
        return false;
    /* Otherwise, request attributes if and only if we don't hold
     * a delegation
     */
    return nfs4_have_delegation(hdr->inode, FMODE_READ) == 0;
}

static void nfs4_proc_write_setup(struct nfs_write_data *data, struct rpc_message *msg)
{
    struct nfs_server *server = NFS_SERVER(data->header->inode);

    if (!nfs4_write_need_cache_consistency_data(data)) {
        data->args.bitmask = NULL;
        data->res.fattr = NULL;
    } else
        data->args.bitmask = server->cache_consistency_bitmask;

    if (!data->write_done_cb)
        data->write_done_cb = nfs4_write_done_cb;
    data->res.server = server;
    data->timestamp   = jiffies;

    msg->rpc_proc = &nfs4_procedures[NFSPROC4_CLNT_WRITE];
    nfs41_init_sequence(&data->args.seq_args, &data->res.seq_res, 1);
}

static void nfs4_proc_write_rpc_prepare(struct rpc_task *task, struct nfs_write_data *data)
{
    if (nfs4_setup_sequence(NFS_SERVER(data->header->inode),
                &data->args.seq_args,
                &data->res.seq_res,
                task))
        return;
    rpc_call_start(task);
}

static void nfs4_proc_commit_rpc_prepare(struct rpc_task *task, struct nfs_commit_data *data)
{
    if (nfs4_setup_sequence(NFS_SERVER(data->inode),
                &data->args.seq_args,
                &data->res.seq_res,
                task))
        return;
    rpc_call_start(task);
}

static int nfs4_commit_done_cb(struct rpc_task *task, struct nfs_commit_data *data)
{
    struct inode *inode = data->inode;

    if (nfs4_async_handle_error(task, NFS_SERVER(inode), NULL) == -EAGAIN) {
        rpc_restart_call_prepare(task);
        return -EAGAIN;
    }
    return 0;
}

static int nfs4_commit_done(struct rpc_task *task, struct nfs_commit_data *data)
{
    if (!nfs4_sequence_done(task, &data->res.seq_res))
        return -EAGAIN;
    return data->commit_done_cb(task, data);
}

static void nfs4_proc_commit_setup(struct nfs_commit_data *data, struct rpc_message *msg)
{
    struct nfs_server *server = NFS_SERVER(data->inode);

    if (data->commit_done_cb == NULL)
        data->commit_done_cb = nfs4_commit_done_cb;
    data->res.server = server;
    msg->rpc_proc = &nfs4_procedures[NFSPROC4_CLNT_COMMIT];
    nfs41_init_sequence(&data->args.seq_args, &data->res.seq_res, 1);
}

struct nfs4_renewdata {
    struct nfs_client   *client;
    unsigned long       timestamp;
};

/*
 * nfs4_proc_async_renew(): This is not one of the nfs_rpc_ops; it is a special
 * standalone procedure for queueing an asynchronous RENEW.
 */
static void nfs4_renew_release(void *calldata)
{
    struct nfs4_renewdata *data = calldata;
    struct nfs_client *clp = data->client;

    if (atomic_read(&clp->cl_count) > 1)
        nfs4_schedule_state_renewal(clp);
    nfs_put_client(clp);
    kfree(data);
}

static void nfs4_renew_done(struct rpc_task *task, void *calldata)
{
    struct nfs4_renewdata *data = calldata;
    struct nfs_client *clp = data->client;
    unsigned long timestamp = data->timestamp;

    if (task->tk_status < 0) {
        /* Unless we're shutting down, schedule state recovery! */
        if (test_bit(NFS_CS_RENEWD, &clp->cl_res_state) == 0)
            return;
        if (task->tk_status != NFS4ERR_CB_PATH_DOWN) {
            nfs4_schedule_lease_recovery(clp);
            return;
        }
        nfs4_schedule_path_down_recovery(clp);
    }
    do_renew_lease(clp, timestamp);
}

static const struct rpc_call_ops nfs4_renew_ops = {
    .rpc_call_done = nfs4_renew_done,
    .rpc_release = nfs4_renew_release,
};

static int nfs4_proc_async_renew(struct nfs_client *clp, struct rpc_cred *cred, unsigned renew_flags)
{
    struct rpc_message msg = {
        .rpc_proc   = &nfs4_procedures[NFSPROC4_CLNT_RENEW],
        .rpc_argp   = clp,
        .rpc_cred   = cred,
    };
    struct nfs4_renewdata *data;

    if (renew_flags == 0)
        return 0;
    if (!atomic_inc_not_zero(&clp->cl_count))
        return -EIO;
    data = kmalloc(sizeof(*data), GFP_NOFS);
    if (data == NULL)
        return -ENOMEM;
    data->client = clp;
    data->timestamp = jiffies;
    return rpc_call_async(clp->cl_rpcclient, &msg, RPC_TASK_SOFT,
            &nfs4_renew_ops, data);
}

static int nfs4_proc_renew(struct nfs_client *clp, struct rpc_cred *cred)
{
    struct rpc_message msg = {
        .rpc_proc   = &nfs4_procedures[NFSPROC4_CLNT_RENEW],
        .rpc_argp   = clp,
        .rpc_cred   = cred,
    };
    unsigned long now = jiffies;
    int status;

    status = rpc_call_sync(clp->cl_rpcclient, &msg, 0);
    if (status < 0)
        return status;
    do_renew_lease(clp, now);
    return 0;
}

static inline int nfs4_server_supports_acls(struct nfs_server *server)
{
    return (server->caps & NFS_CAP_ACLS)
        && (server->acl_bitmask & ACL4_SUPPORT_ALLOW_ACL)
        && (server->acl_bitmask & ACL4_SUPPORT_DENY_ACL);
}

/* Assuming that XATTR_SIZE_MAX is a multiple of PAGE_SIZE, and that
 * it's OK to put sizeof(void) * (XATTR_SIZE_MAX/PAGE_SIZE) bytes on
 * the stack.
 */
#define NFS4ACL_MAXPAGES DIV_ROUND_UP(XATTR_SIZE_MAX, PAGE_SIZE)

static int buf_to_pages_noslab(const void *buf, size_t buflen,
        struct page **pages, unsigned int *pgbase)
{
    struct page *newpage, **spages;
    int rc = 0;
    size_t len;
    spages = pages;

    do {
        len = min_t(size_t, PAGE_SIZE, buflen);
        newpage = alloc_page(GFP_KERNEL);

        if (newpage == NULL)
            goto unwind;
        memcpy(page_address(newpage), buf, len);
                buf += len;
                buflen -= len;
        *pages++ = newpage;
        rc++;
    } while (buflen != 0);

    return rc;

unwind:
    for(; rc > 0; rc--)
        __free_page(spages[rc-1]);
    return -ENOMEM;
}

struct nfs4_cached_acl {
    int cached;
    size_t len;
    char data[0];
};

static void nfs4_set_cached_acl(struct inode *inode, struct nfs4_cached_acl *acl)
{
    struct nfs_inode *nfsi = NFS_I(inode);

    spin_lock(&inode->i_lock);
    kfree(nfsi->nfs4_acl);
    nfsi->nfs4_acl = acl;
    spin_unlock(&inode->i_lock);
}

static void nfs4_zap_acl_attr(struct inode *inode)
{
    nfs4_set_cached_acl(inode, NULL);
}

static inline ssize_t nfs4_read_cached_acl(struct inode *inode, char *buf, size_t buflen)
{
    struct nfs_inode *nfsi = NFS_I(inode);
    struct nfs4_cached_acl *acl;
    int ret = -ENOENT;

    spin_lock(&inode->i_lock);
    acl = nfsi->nfs4_acl;
    if (acl == NULL)
        goto out;
    if (buf == NULL) /* user is just asking for length */
        goto out_len;
    if (acl->cached == 0)
        goto out;
    ret = -ERANGE; /* see getxattr(2) man page */
    if (acl->len > buflen)
        goto out;
    memcpy(buf, acl->data, acl->len);
out_len:
    ret = acl->len;
out:
    spin_unlock(&inode->i_lock);
    return ret;
}

static void nfs4_write_cached_acl(struct inode *inode, struct page **pages, size_t pgbase, size_t acl_len)
{
    struct nfs4_cached_acl *acl;
    size_t buflen = sizeof(*acl) + acl_len;

    if (buflen <= PAGE_SIZE) {
        acl = kmalloc(buflen, GFP_KERNEL);
        if (acl == NULL)
            goto out;
        acl->cached = 1;
        _copy_from_pages(acl->data, pages, pgbase, acl_len);
    } else {
        acl = kmalloc(sizeof(*acl), GFP_KERNEL);
        if (acl == NULL)
            goto out;
        acl->cached = 0;
    }
    acl->len = acl_len;
out:
    nfs4_set_cached_acl(inode, acl);
}

/*
 * The getxattr API returns the required buffer length when called with a
 * NULL buf. The NFSv4 acl tool then calls getxattr again after allocating
 * the required buf.  On a NULL buf, we send a page of data to the server
 * guessing that the ACL request can be serviced by a page. If so, we cache
 * up to the page of ACL data, and the 2nd call to getxattr is serviced by
 * the cache. If not so, we throw away the page, and cache the required
 * length. The next getxattr call will then produce another round trip to
 * the server, this time with the input buf of the required size.
 */
static ssize_t __nfs4_get_acl_uncached(struct inode *inode, void *buf, size_t buflen)
{
    struct page *pages[NFS4ACL_MAXPAGES] = {NULL, };
    struct nfs_getaclargs args = {
        .fh = NFS_FH(inode),
        .acl_pages = pages,
        .acl_len = buflen,
    };
    struct nfs_getaclres res = {
        .acl_len = buflen,
    };
    struct rpc_message msg = {
        .rpc_proc = &nfs4_procedures[NFSPROC4_CLNT_GETACL],
        .rpc_argp = &args,
        .rpc_resp = &res,
    };
    unsigned int npages = DIV_ROUND_UP(buflen, PAGE_SIZE);
    int ret = -ENOMEM, i;

    /* As long as we're doing a round trip to the server anyway,
     * let's be prepared for a page of acl data. */
    if (npages == 0)
        npages = 1;
    if (npages > ARRAY_SIZE(pages))
        return -ERANGE;

    for (i = 0; i < npages; i++) {
        pages[i] = alloc_page(GFP_KERNEL);
        if (!pages[i])
            goto out_free;
    }

    /* for decoding across pages */
    res.acl_scratch = alloc_page(GFP_KERNEL);
    if (!res.acl_scratch)
        goto out_free;

    args.acl_len = npages * PAGE_SIZE;
    args.acl_pgbase = 0;

    dprintk("%s  buf %p buflen %zu npages %d args.acl_len %zu\n",
        __func__, buf, buflen, npages, args.acl_len);
    ret = nfs4_call_sync(NFS_SERVER(inode)->client, NFS_SERVER(inode),
                 &msg, &args.seq_args, &res.seq_res, 0);
    if (ret)
        goto out_free;

    /* Handle the case where the passed-in buffer is too short */
    if (res.acl_flags & NFS4_ACL_TRUNC) {
        /* Did the user only issue a request for the acl length? */
        if (buf == NULL)
            goto out_ok;
        ret = -ERANGE;
        goto out_free;
    }
    nfs4_write_cached_acl(inode, pages, res.acl_data_offset, res.acl_len);
    if (buf)
        _copy_from_pages(buf, pages, res.acl_data_offset, res.acl_len);
out_ok:
    ret = res.acl_len;
out_free:
    for (i = 0; i < npages; i++)
        if (pages[i])
            __free_page(pages[i]);
    if (res.acl_scratch)
        __free_page(res.acl_scratch);
    return ret;
}

static ssize_t nfs4_get_acl_uncached(struct inode *inode, void *buf, size_t buflen)
{
    struct nfs4_exception exception = { };
    ssize_t ret;
    do {
        ret = __nfs4_get_acl_uncached(inode, buf, buflen);
        if (ret >= 0)
            break;
        ret = nfs4_handle_exception(NFS_SERVER(inode), ret, &exception);
    } while (exception.retry);
    return ret;
}

static ssize_t nfs4_proc_get_acl(struct inode *inode, void *buf, size_t buflen)
{
    struct nfs_server *server = NFS_SERVER(inode);
    int ret;

    if (!nfs4_server_supports_acls(server))
        return -EOPNOTSUPP;
    ret = nfs_revalidate_inode(server, inode);
    if (ret < 0)
        return ret;
    if (NFS_I(inode)->cache_validity & NFS_INO_INVALID_ACL)
        nfs_zap_acl_cache(inode);
    ret = nfs4_read_cached_acl(inode, buf, buflen);
    if (ret != -ENOENT)
        /* -ENOENT is returned if there is no ACL or if there is an ACL
         * but no cached acl data, just the acl length */
        return ret;
    return nfs4_get_acl_uncached(inode, buf, buflen);
}

static int __nfs4_proc_set_acl(struct inode *inode, const void *buf, size_t buflen)
{
    struct nfs_server *server = NFS_SERVER(inode);
    struct page *pages[NFS4ACL_MAXPAGES];
    struct nfs_setaclargs arg = {
        .fh     = NFS_FH(inode),
        .acl_pages  = pages,
        .acl_len    = buflen,
    };
    struct nfs_setaclres res;
    struct rpc_message msg = {
        .rpc_proc   = &nfs4_procedures[NFSPROC4_CLNT_SETACL],
        .rpc_argp   = &arg,
        .rpc_resp   = &res,
    };
    unsigned int npages = DIV_ROUND_UP(buflen, PAGE_SIZE);
    int ret, i;

    if (!nfs4_server_supports_acls(server))
        return -EOPNOTSUPP;
    if (npages > ARRAY_SIZE(pages))
        return -ERANGE;
    i = buf_to_pages_noslab(buf, buflen, arg.acl_pages, &arg.acl_pgbase);
    if (i < 0)
        return i;
    nfs4_inode_return_delegation(inode);
    ret = nfs4_call_sync(server->client, server, &msg, &arg.seq_args, &res.seq_res, 1);

    /*
     * Free each page after tx, so the only ref left is
     * held by the network stack
     */
    for (; i > 0; i--)
        put_page(pages[i-1]);

    /*
     * Acl update can result in inode attribute update.
     * so mark the attribute cache invalid.
     */
    spin_lock(&inode->i_lock);
    NFS_I(inode)->cache_validity |= NFS_INO_INVALID_ATTR;
    spin_unlock(&inode->i_lock);
    nfs_access_zap_cache(inode);
    nfs_zap_acl_cache(inode);
    return ret;
}

static int nfs4_proc_set_acl(struct inode *inode, const void *buf, size_t buflen)
{
    struct nfs4_exception exception = { };
    int err;
    do {
        err = nfs4_handle_exception(NFS_SERVER(inode),
                __nfs4_proc_set_acl(inode, buf, buflen),
                &exception);
    } while (exception.retry);
    return err;
}

static int
nfs4_async_handle_error(struct rpc_task *task, const struct nfs_server *server, struct nfs4_state *state)
{
    struct nfs_client *clp = server->nfs_client;

    if (task->tk_status >= 0)
        return 0;
    switch(task->tk_status) {
        case -NFS4ERR_DELEG_REVOKED:
        case -NFS4ERR_ADMIN_REVOKED:
        case -NFS4ERR_BAD_STATEID:
            if (state == NULL)
                break;
            nfs_remove_bad_delegation(state->inode);
        case -NFS4ERR_OPENMODE:
            if (state == NULL)
                break;
            nfs4_schedule_stateid_recovery(server, state);
            goto wait_on_recovery;
        case -NFS4ERR_EXPIRED:
            if (state != NULL)
                nfs4_schedule_stateid_recovery(server, state);
        case -NFS4ERR_STALE_STATEID:
        case -NFS4ERR_STALE_CLIENTID:
            nfs4_schedule_lease_recovery(clp);
            goto wait_on_recovery;
#if defined(CONFIG_NFS_V4_1)
        case -NFS4ERR_BADSESSION:
        case -NFS4ERR_BADSLOT:
        case -NFS4ERR_BAD_HIGH_SLOT:
        case -NFS4ERR_DEADSESSION:
        case -NFS4ERR_CONN_NOT_BOUND_TO_SESSION:
        case -NFS4ERR_SEQ_FALSE_RETRY:
        case -NFS4ERR_SEQ_MISORDERED:
            dprintk("%s ERROR %d, Reset session\n", __func__,
                task->tk_status);
            nfs4_schedule_session_recovery(clp->cl_session, task->tk_status);
            task->tk_status = 0;
            return -EAGAIN;
#endif /* CONFIG_NFS_V4_1 */
        case -NFS4ERR_DELAY:
            nfs_inc_server_stats(server, NFSIOS_DELAY);
        case -NFS4ERR_GRACE:
        case -EKEYEXPIRED:
            rpc_delay(task, NFS4_POLL_RETRY_MAX);
            task->tk_status = 0;
            return -EAGAIN;
        case -NFS4ERR_RETRY_UNCACHED_REP:
        case -NFS4ERR_OLD_STATEID:
            task->tk_status = 0;
            return -EAGAIN;
    }
    task->tk_status = nfs4_map_errors(task->tk_status);
    return 0;
wait_on_recovery:
    rpc_sleep_on(&clp->cl_rpcwaitq, task, NULL);
    if (test_bit(NFS4CLNT_MANAGER_RUNNING, &clp->cl_state) == 0)
        rpc_wake_up_queued_task(&clp->cl_rpcwaitq, task);
    task->tk_status = 0;
    return -EAGAIN;
}

static void nfs4_init_boot_verifier(const struct nfs_client *clp,
                    nfs4_verifier *bootverf)
{
    __be32 verf[2];

    if (test_bit(NFS4CLNT_PURGE_STATE, &clp->cl_state)) {
        /* An impossible timestamp guarantees this value
         * will never match a generated boot time. */
        verf[0] = 0;
        verf[1] = (__be32)(NSEC_PER_SEC + 1);
    } else {
        struct nfs_net *nn = net_generic(clp->cl_net, nfs_net_id);
        verf[0] = (__be32)nn->boot_time.tv_sec;
        verf[1] = (__be32)nn->boot_time.tv_nsec;
    }
    memcpy(bootverf->data, verf, sizeof(bootverf->data));
}

static unsigned int
nfs4_init_nonuniform_client_string(const struct nfs_client *clp,
                   char *buf, size_t len)
{
    unsigned int result;

    rcu_read_lock();
    result = scnprintf(buf, len, "Linux NFSv4.0 %s/%s %s",
                clp->cl_ipaddr,
                rpc_peeraddr2str(clp->cl_rpcclient,
                            RPC_DISPLAY_ADDR),
                rpc_peeraddr2str(clp->cl_rpcclient,
                            RPC_DISPLAY_PROTO));
    rcu_read_unlock();
    return result;
}

static unsigned int
nfs4_init_uniform_client_string(const struct nfs_client *clp,
                char *buf, size_t len)
{
    char *nodename = clp->cl_rpcclient->cl_nodename;

    if (nfs4_client_id_uniquifier[0] != '\0')
        nodename = nfs4_client_id_uniquifier;
    return scnprintf(buf, len, "Linux NFSv%u.%u %s",
                clp->rpc_ops->version, clp->cl_minorversion,
                nodename);
}

int nfs4_proc_setclientid(struct nfs_client *clp, u32 program,
        unsigned short port, struct rpc_cred *cred,
        struct nfs4_setclientid_res *res)
{
    nfs4_verifier sc_verifier;
    struct nfs4_setclientid setclientid = {
        .sc_verifier = &sc_verifier,
        .sc_prog = program,
        .sc_cb_ident = clp->cl_cb_ident,
    };
    struct rpc_message msg = {
        .rpc_proc = &nfs4_procedures[NFSPROC4_CLNT_SETCLIENTID],
        .rpc_argp = &setclientid,
        .rpc_resp = res,
        .rpc_cred = cred,
    };
    int status;

    /* nfs_client_id4 */
    nfs4_init_boot_verifier(clp, &sc_verifier);
    if (test_bit(NFS_CS_MIGRATION, &clp->cl_flags))
        setclientid.sc_name_len =
                nfs4_init_uniform_client_string(clp,
                        setclientid.sc_name,
                        sizeof(setclientid.sc_name));
    else
        setclientid.sc_name_len =
                nfs4_init_nonuniform_client_string(clp,
                        setclientid.sc_name,
                        sizeof(setclientid.sc_name));
    /* cb_client4 */
    rcu_read_lock();
    setclientid.sc_netid_len = scnprintf(setclientid.sc_netid,
                sizeof(setclientid.sc_netid),
                rpc_peeraddr2str(clp->cl_rpcclient,
                            RPC_DISPLAY_NETID));
    rcu_read_unlock();
    setclientid.sc_uaddr_len = scnprintf(setclientid.sc_uaddr,
                sizeof(setclientid.sc_uaddr), "%s.%u.%u",
                clp->cl_ipaddr, port >> 8, port & 255);

    dprintk("NFS call  setclientid auth=%s, '%.*s'\n",
        clp->cl_rpcclient->cl_auth->au_ops->au_name,
        setclientid.sc_name_len, setclientid.sc_name);
    status = rpc_call_sync(clp->cl_rpcclient, &msg, RPC_TASK_TIMEOUT);
    dprintk("NFS reply setclientid: %d\n", status);
    return status;
}

int nfs4_proc_setclientid_confirm(struct nfs_client *clp,
        struct nfs4_setclientid_res *arg,
        struct rpc_cred *cred)
{
    struct nfs_fsinfo fsinfo;
    struct rpc_message msg = {
        .rpc_proc = &nfs4_procedures[NFSPROC4_CLNT_SETCLIENTID_CONFIRM],
        .rpc_argp = arg,
        .rpc_resp = &fsinfo,
        .rpc_cred = cred,
    };
    unsigned long now;
    int status;

    dprintk("NFS call  setclientid_confirm auth=%s, (client ID %llx)\n",
        clp->cl_rpcclient->cl_auth->au_ops->au_name,
        clp->cl_clientid);
    now = jiffies;
    status = rpc_call_sync(clp->cl_rpcclient, &msg, RPC_TASK_TIMEOUT);
    if (status == 0) {
        spin_lock(&clp->cl_lock);
        clp->cl_lease_time = fsinfo.lease_time * HZ;
        clp->cl_last_renewal = now;
        spin_unlock(&clp->cl_lock);
    }
    dprintk("NFS reply setclientid_confirm: %d\n", status);
    return status;
}

struct nfs4_delegreturndata {
    struct nfs4_delegreturnargs args;
    struct nfs4_delegreturnres res;
    struct nfs_fh fh;
    nfs4_stateid stateid;
    unsigned long timestamp;
    struct nfs_fattr fattr;
    int rpc_status;
};

static void nfs4_delegreturn_done(struct rpc_task *task, void *calldata)
{
    struct nfs4_delegreturndata *data = calldata;

    if (!nfs4_sequence_done(task, &data->res.seq_res))
        return;

    switch (task->tk_status) {
    case -NFS4ERR_STALE_STATEID:
    case -NFS4ERR_EXPIRED:
    case 0:
        renew_lease(data->res.server, data->timestamp);
        break;
    default:
        if (nfs4_async_handle_error(task, data->res.server, NULL) ==
                -EAGAIN) {
            rpc_restart_call_prepare(task);
            return;
        }
    }
    data->rpc_status = task->tk_status;
}

static void nfs4_delegreturn_release(void *calldata)
{
    kfree(calldata);
}

#if defined(CONFIG_NFS_V4_1)
static void nfs4_delegreturn_prepare(struct rpc_task *task, void *data)
{
    struct nfs4_delegreturndata *d_data;

    d_data = (struct nfs4_delegreturndata *)data;

    if (nfs4_setup_sequence(d_data->res.server,
                &d_data->args.seq_args,
                &d_data->res.seq_res, task))
        return;
    rpc_call_start(task);
}
#endif /* CONFIG_NFS_V4_1 */

static const struct rpc_call_ops nfs4_delegreturn_ops = {
#if defined(CONFIG_NFS_V4_1)
    .rpc_call_prepare = nfs4_delegreturn_prepare,
#endif /* CONFIG_NFS_V4_1 */
    .rpc_call_done = nfs4_delegreturn_done,
    .rpc_release = nfs4_delegreturn_release,
};

static int _nfs4_proc_delegreturn(struct inode *inode, struct rpc_cred *cred, const nfs4_stateid *stateid, int issync)
{
    struct nfs4_delegreturndata *data;
    struct nfs_server *server = NFS_SERVER(inode);
    struct rpc_task *task;
    struct rpc_message msg = {
        .rpc_proc = &nfs4_procedures[NFSPROC4_CLNT_DELEGRETURN],
        .rpc_cred = cred,
    };
    struct rpc_task_setup task_setup_data = {
        .rpc_client = server->client,
        .rpc_message = &msg,
        .callback_ops = &nfs4_delegreturn_ops,
        .flags = RPC_TASK_ASYNC,
    };
    int status = 0;

    data = kzalloc(sizeof(*data), GFP_NOFS);
    if (data == NULL)
        return -ENOMEM;
    nfs41_init_sequence(&data->args.seq_args, &data->res.seq_res, 1);
    data->args.fhandle = &data->fh;
    data->args.stateid = &data->stateid;
    data->args.bitmask = server->cache_consistency_bitmask;
    nfs_copy_fh(&data->fh, NFS_FH(inode));
    nfs4_stateid_copy(&data->stateid, stateid);
    data->res.fattr = &data->fattr;
    data->res.server = server;
    nfs_fattr_init(data->res.fattr);
    data->timestamp = jiffies;
    data->rpc_status = 0;

    task_setup_data.callback_data = data;
    msg.rpc_argp = &data->args;
    msg.rpc_resp = &data->res;
    task = rpc_run_task(&task_setup_data);
    if (IS_ERR(task))
        return PTR_ERR(task);
    if (!issync)
        goto out;
    status = nfs4_wait_for_completion_rpc_task(task);
    if (status != 0)
        goto out;
    status = data->rpc_status;
    if (status == 0)
        nfs_post_op_update_inode_force_wcc(inode, &data->fattr);
    else
        nfs_refresh_inode(inode, &data->fattr);
out:
    rpc_put_task(task);
    return status;
}

int nfs4_proc_delegreturn(struct inode *inode, struct rpc_cred *cred, const nfs4_stateid *stateid, int issync)
{
    struct nfs_server *server = NFS_SERVER(inode);
    struct nfs4_exception exception = { };
    int err;
    do {
        err = _nfs4_proc_delegreturn(inode, cred, stateid, issync);
        switch (err) {
            case -NFS4ERR_STALE_STATEID:
            case -NFS4ERR_EXPIRED:
            case 0:
                return 0;
        }
        err = nfs4_handle_exception(server, err, &exception);
    } while (exception.retry);
    return err;
}

#define NFS4_LOCK_MINTIMEOUT (1 * HZ)
#define NFS4_LOCK_MAXTIMEOUT (30 * HZ)

/* 
 * sleep, with exponential backoff, and retry the LOCK operation. 
 */
static unsigned long
nfs4_set_lock_task_retry(unsigned long timeout)
{
    freezable_schedule_timeout_killable(timeout);
    timeout <<= 1;
    if (timeout > NFS4_LOCK_MAXTIMEOUT)
        return NFS4_LOCK_MAXTIMEOUT;
    return timeout;
}

static int _nfs4_proc_getlk(struct nfs4_state *state, int cmd, struct file_lock *request)
{
    struct inode *inode = state->inode;
    struct nfs_server *server = NFS_SERVER(inode);
    struct nfs_client *clp = server->nfs_client;
    struct nfs_lockt_args arg = {
        .fh = NFS_FH(inode),
        .fl = request,
    };
    struct nfs_lockt_res res = {
        .denied = request,
    };
    struct rpc_message msg = {
        .rpc_proc   = &nfs4_procedures[NFSPROC4_CLNT_LOCKT],
        .rpc_argp       = &arg,
        .rpc_resp       = &res,
        .rpc_cred   = state->owner->so_cred,
    };
    struct nfs4_lock_state *lsp;
    int status;

    arg.lock_owner.clientid = clp->cl_clientid;
    status = nfs4_set_lock_state(state, request);
    if (status != 0)
        goto out;
    lsp = request->fl_u.nfs4_fl.owner;
    arg.lock_owner.id = lsp->ls_seqid.owner_id;
    arg.lock_owner.s_dev = server->s_dev;
    status = nfs4_call_sync(server->client, server, &msg, &arg.seq_args, &res.seq_res, 1);
    switch (status) {
        case 0:
            request->fl_type = F_UNLCK;
            break;
        case -NFS4ERR_DENIED:
            status = 0;
    }
    request->fl_ops->fl_release_private(request);
out:
    return status;
}

static int nfs4_proc_getlk(struct nfs4_state *state, int cmd, struct file_lock *request)
{
    struct nfs4_exception exception = { };
    int err;

    do {
        err = nfs4_handle_exception(NFS_SERVER(state->inode),
                _nfs4_proc_getlk(state, cmd, request),
                &exception);
    } while (exception.retry);
    return err;
}

static int do_vfs_lock(struct file *file, struct file_lock *fl)
{
    int res = 0;
    switch (fl->fl_flags & (FL_POSIX|FL_FLOCK)) {
        case FL_POSIX:
            res = posix_lock_file_wait(file, fl);
            break;
        case FL_FLOCK:
            res = flock_lock_file_wait(file, fl);
            break;
        default:
            BUG();
    }
    return res;
}

struct nfs4_unlockdata {
    struct nfs_locku_args arg;
    struct nfs_locku_res res;
    struct nfs4_lock_state *lsp;
    struct nfs_open_context *ctx;
    struct file_lock fl;
    const struct nfs_server *server;
    unsigned long timestamp;
};

static struct nfs4_unlockdata *nfs4_alloc_unlockdata(struct file_lock *fl,
        struct nfs_open_context *ctx,
        struct nfs4_lock_state *lsp,
        struct nfs_seqid *seqid)
{
    struct nfs4_unlockdata *p;
    struct inode *inode = lsp->ls_state->inode;

    p = kzalloc(sizeof(*p), GFP_NOFS);
    if (p == NULL)
        return NULL;
    p->arg.fh = NFS_FH(inode);
    p->arg.fl = &p->fl;
    p->arg.seqid = seqid;
    p->res.seqid = seqid;
    p->arg.stateid = &lsp->ls_stateid;
    p->lsp = lsp;
    atomic_inc(&lsp->ls_count);
    /* Ensure we don't close file until we're done freeing locks! */
    p->ctx = get_nfs_open_context(ctx);
    memcpy(&p->fl, fl, sizeof(p->fl));
    p->server = NFS_SERVER(inode);
    return p;
}

static void nfs4_locku_release_calldata(void *data)
{
    struct nfs4_unlockdata *calldata = data;
    nfs_free_seqid(calldata->arg.seqid);
    nfs4_put_lock_state(calldata->lsp);
    put_nfs_open_context(calldata->ctx);
    kfree(calldata);
}

static void nfs4_locku_done(struct rpc_task *task, void *data)
{
    struct nfs4_unlockdata *calldata = data;

    if (!nfs4_sequence_done(task, &calldata->res.seq_res))
        return;
    switch (task->tk_status) {
        case 0:
            nfs4_stateid_copy(&calldata->lsp->ls_stateid,
                    &calldata->res.stateid);
            renew_lease(calldata->server, calldata->timestamp);
            break;
        case -NFS4ERR_BAD_STATEID:
        case -NFS4ERR_OLD_STATEID:
        case -NFS4ERR_STALE_STATEID:
        case -NFS4ERR_EXPIRED:
            break;
        default:
            if (nfs4_async_handle_error(task, calldata->server, NULL) == -EAGAIN)
                rpc_restart_call_prepare(task);
    }
    nfs_release_seqid(calldata->arg.seqid);
}

static void nfs4_locku_prepare(struct rpc_task *task, void *data)
{
    struct nfs4_unlockdata *calldata = data;

    if (nfs_wait_on_sequence(calldata->arg.seqid, task) != 0)
        return;
    if (test_bit(NFS_LOCK_INITIALIZED, &calldata->lsp->ls_flags) == 0) {
        /* Note: exit _without_ running nfs4_locku_done */
        task->tk_action = NULL;
        return;
    }
    calldata->timestamp = jiffies;
    if (nfs4_setup_sequence(calldata->server,
                &calldata->arg.seq_args,
                &calldata->res.seq_res,
                task) != 0)
        nfs_release_seqid(calldata->arg.seqid);
    else
        rpc_call_start(task);
}

static const struct rpc_call_ops nfs4_locku_ops = {
    .rpc_call_prepare = nfs4_locku_prepare,
    .rpc_call_done = nfs4_locku_done,
    .rpc_release = nfs4_locku_release_calldata,
};

static struct rpc_task *nfs4_do_unlck(struct file_lock *fl,
        struct nfs_open_context *ctx,
        struct nfs4_lock_state *lsp,
        struct nfs_seqid *seqid)
{
    struct nfs4_unlockdata *data;
    struct rpc_message msg = {
        .rpc_proc = &nfs4_procedures[NFSPROC4_CLNT_LOCKU],
        .rpc_cred = ctx->cred,
    };
    struct rpc_task_setup task_setup_data = {
        .rpc_client = NFS_CLIENT(lsp->ls_state->inode),
        .rpc_message = &msg,
        .callback_ops = &nfs4_locku_ops,
        .workqueue = nfsiod_workqueue,
        .flags = RPC_TASK_ASYNC,
    };

    /* Ensure this is an unlock - when canceling a lock, the
     * canceled lock is passed in, and it won't be an unlock.
     */
    fl->fl_type = F_UNLCK;

    data = nfs4_alloc_unlockdata(fl, ctx, lsp, seqid);
    if (data == NULL) {
        nfs_free_seqid(seqid);
        return ERR_PTR(-ENOMEM);
    }

    nfs41_init_sequence(&data->arg.seq_args, &data->res.seq_res, 1);
    msg.rpc_argp = &data->arg;
    msg.rpc_resp = &data->res;
    task_setup_data.callback_data = data;
    return rpc_run_task(&task_setup_data);
}

static int nfs4_proc_unlck(struct nfs4_state *state, int cmd, struct file_lock *request)
{
    struct nfs_inode *nfsi = NFS_I(state->inode);
    struct nfs_seqid *seqid;
    struct nfs4_lock_state *lsp;
    struct rpc_task *task;
    int status = 0;
    unsigned char fl_flags = request->fl_flags;

    status = nfs4_set_lock_state(state, request);
    /* Unlock _before_ we do the RPC call */
    request->fl_flags |= FL_EXISTS;
    down_read(&nfsi->rwsem);
    if (do_vfs_lock(request->fl_file, request) == -ENOENT) {
        up_read(&nfsi->rwsem);
        goto out;
    }
    up_read(&nfsi->rwsem);
    if (status != 0)
        goto out;
    /* Is this a delegated lock? */
    if (test_bit(NFS_DELEGATED_STATE, &state->flags))
        goto out;
    lsp = request->fl_u.nfs4_fl.owner;
    seqid = nfs_alloc_seqid(&lsp->ls_seqid, GFP_KERNEL);
    status = -ENOMEM;
    if (seqid == NULL)
        goto out;
    task = nfs4_do_unlck(request, nfs_file_open_context(request->fl_file), lsp, seqid);
    status = PTR_ERR(task);
    if (IS_ERR(task))
        goto out;
    status = nfs4_wait_for_completion_rpc_task(task);
    rpc_put_task(task);
out:
    request->fl_flags = fl_flags;
    return status;
}

struct nfs4_lockdata {
    struct nfs_lock_args arg;
    struct nfs_lock_res res;
    struct nfs4_lock_state *lsp;
    struct nfs_open_context *ctx;
    struct file_lock fl;
    unsigned long timestamp;
    int rpc_status;
    int cancelled;
    struct nfs_server *server;
};

static struct nfs4_lockdata *nfs4_alloc_lockdata(struct file_lock *fl,
        struct nfs_open_context *ctx, struct nfs4_lock_state *lsp,
        gfp_t gfp_mask)
{
    struct nfs4_lockdata *p;
    struct inode *inode = lsp->ls_state->inode;
    struct nfs_server *server = NFS_SERVER(inode);

    p = kzalloc(sizeof(*p), gfp_mask);
    if (p == NULL)
        return NULL;

    p->arg.fh = NFS_FH(inode);
    p->arg.fl = &p->fl;
    p->arg.open_seqid = nfs_alloc_seqid(&lsp->ls_state->owner->so_seqid, gfp_mask);
    if (p->arg.open_seqid == NULL)
        goto out_free;
    p->arg.lock_seqid = nfs_alloc_seqid(&lsp->ls_seqid, gfp_mask);
    if (p->arg.lock_seqid == NULL)
        goto out_free_seqid;
    p->arg.lock_stateid = &lsp->ls_stateid;
    p->arg.lock_owner.clientid = server->nfs_client->cl_clientid;
    p->arg.lock_owner.id = lsp->ls_seqid.owner_id;
    p->arg.lock_owner.s_dev = server->s_dev;
    p->res.lock_seqid = p->arg.lock_seqid;
    p->lsp = lsp;
    p->server = server;
    atomic_inc(&lsp->ls_count);
    p->ctx = get_nfs_open_context(ctx);
    memcpy(&p->fl, fl, sizeof(p->fl));
    return p;
out_free_seqid:
    nfs_free_seqid(p->arg.open_seqid);
out_free:
    kfree(p);
    return NULL;
}

static void nfs4_lock_prepare(struct rpc_task *task, void *calldata)
{
    struct nfs4_lockdata *data = calldata;
    struct nfs4_state *state = data->lsp->ls_state;

    dprintk("%s: begin!\n", __func__);
    if (nfs_wait_on_sequence(data->arg.lock_seqid, task) != 0)
        return;
    /* Do we need to do an open_to_lock_owner? */
    if (!(data->arg.lock_seqid->sequence->flags & NFS_SEQID_CONFIRMED)) {
        if (nfs_wait_on_sequence(data->arg.open_seqid, task) != 0)
            goto out_release_lock_seqid;
        data->arg.open_stateid = &state->stateid;
        data->arg.new_lock_owner = 1;
        data->res.open_seqid = data->arg.open_seqid;
    } else
        data->arg.new_lock_owner = 0;
    data->timestamp = jiffies;
    if (nfs4_setup_sequence(data->server,
                &data->arg.seq_args,
                &data->res.seq_res,
                task) == 0) {
        rpc_call_start(task);
        return;
    }
    nfs_release_seqid(data->arg.open_seqid);
out_release_lock_seqid:
    nfs_release_seqid(data->arg.lock_seqid);
    dprintk("%s: done!, ret = %d\n", __func__, task->tk_status);
}

static void nfs4_recover_lock_prepare(struct rpc_task *task, void *calldata)
{
    rpc_task_set_priority(task, RPC_PRIORITY_PRIVILEGED);
    nfs4_lock_prepare(task, calldata);
}

static void nfs4_lock_done(struct rpc_task *task, void *calldata)
{
    struct nfs4_lockdata *data = calldata;

    dprintk("%s: begin!\n", __func__);

    if (!nfs4_sequence_done(task, &data->res.seq_res))
        return;

    data->rpc_status = task->tk_status;
    if (data->arg.new_lock_owner != 0) {
        if (data->rpc_status == 0)
            nfs_confirm_seqid(&data->lsp->ls_seqid, 0);
        else
            goto out;
    }
    if (data->rpc_status == 0) {
        nfs4_stateid_copy(&data->lsp->ls_stateid, &data->res.stateid);
        set_bit(NFS_LOCK_INITIALIZED, &data->lsp->ls_flags);
        renew_lease(NFS_SERVER(data->ctx->dentry->d_inode), data->timestamp);
    }
out:
    dprintk("%s: done, ret = %d!\n", __func__, data->rpc_status);
}

static void nfs4_lock_release(void *calldata)
{
    struct nfs4_lockdata *data = calldata;

    dprintk("%s: begin!\n", __func__);
    nfs_free_seqid(data->arg.open_seqid);
    if (data->cancelled != 0) {
        struct rpc_task *task;
        task = nfs4_do_unlck(&data->fl, data->ctx, data->lsp,
                data->arg.lock_seqid);
        if (!IS_ERR(task))
            rpc_put_task_async(task);
        dprintk("%s: cancelling lock!\n", __func__);
    } else
        nfs_free_seqid(data->arg.lock_seqid);
    nfs4_put_lock_state(data->lsp);
    put_nfs_open_context(data->ctx);
    kfree(data);
    dprintk("%s: done!\n", __func__);
}

static const struct rpc_call_ops nfs4_lock_ops = {
    .rpc_call_prepare = nfs4_lock_prepare,
    .rpc_call_done = nfs4_lock_done,
    .rpc_release = nfs4_lock_release,
};

static const struct rpc_call_ops nfs4_recover_lock_ops = {
    .rpc_call_prepare = nfs4_recover_lock_prepare,
    .rpc_call_done = nfs4_lock_done,
    .rpc_release = nfs4_lock_release,
};

static void nfs4_handle_setlk_error(struct nfs_server *server, struct nfs4_lock_state *lsp, int new_lock_owner, int error)
{
    switch (error) {
    case -NFS4ERR_ADMIN_REVOKED:
    case -NFS4ERR_BAD_STATEID:
        lsp->ls_seqid.flags &= ~NFS_SEQID_CONFIRMED;
        if (new_lock_owner != 0 ||
           test_bit(NFS_LOCK_INITIALIZED, &lsp->ls_flags) != 0)
            nfs4_schedule_stateid_recovery(server, lsp->ls_state);
        break;
    case -NFS4ERR_STALE_STATEID:
        lsp->ls_seqid.flags &= ~NFS_SEQID_CONFIRMED;
    case -NFS4ERR_EXPIRED:
        nfs4_schedule_lease_recovery(server->nfs_client);
    };
}

static int _nfs4_do_setlk(struct nfs4_state *state, int cmd, struct file_lock *fl, int recovery_type)
{
    struct nfs4_lockdata *data;
    struct rpc_task *task;
    struct rpc_message msg = {
        .rpc_proc = &nfs4_procedures[NFSPROC4_CLNT_LOCK],
        .rpc_cred = state->owner->so_cred,
    };
    struct rpc_task_setup task_setup_data = {
        .rpc_client = NFS_CLIENT(state->inode),
        .rpc_message = &msg,
        .callback_ops = &nfs4_lock_ops,
        .workqueue = nfsiod_workqueue,
        .flags = RPC_TASK_ASYNC,
    };
    int ret;

    dprintk("%s: begin!\n", __func__);
    data = nfs4_alloc_lockdata(fl, nfs_file_open_context(fl->fl_file),
            fl->fl_u.nfs4_fl.owner,
            recovery_type == NFS_LOCK_NEW ? GFP_KERNEL : GFP_NOFS);
    if (data == NULL)
        return -ENOMEM;
    if (IS_SETLKW(cmd))
        data->arg.block = 1;
    if (recovery_type > NFS_LOCK_NEW) {
        if (recovery_type == NFS_LOCK_RECLAIM)
            data->arg.reclaim = NFS_LOCK_RECLAIM;
        task_setup_data.callback_ops = &nfs4_recover_lock_ops;
    }
    nfs41_init_sequence(&data->arg.seq_args, &data->res.seq_res, 1);
    msg.rpc_argp = &data->arg;
    msg.rpc_resp = &data->res;
    task_setup_data.callback_data = data;
    task = rpc_run_task(&task_setup_data);
    if (IS_ERR(task))
        return PTR_ERR(task);
    ret = nfs4_wait_for_completion_rpc_task(task);
    if (ret == 0) {
        ret = data->rpc_status;
        if (ret)
            nfs4_handle_setlk_error(data->server, data->lsp,
                    data->arg.new_lock_owner, ret);
    } else
        data->cancelled = 1;
    rpc_put_task(task);
    dprintk("%s: done, ret = %d!\n", __func__, ret);
    return ret;
}

static int nfs4_lock_reclaim(struct nfs4_state *state, struct file_lock *request)
{
    struct nfs_server *server = NFS_SERVER(state->inode);
    struct nfs4_exception exception = {
        .inode = state->inode,
    };
    int err;

    do {
        /* Cache the lock if possible... */
        if (test_bit(NFS_DELEGATED_STATE, &state->flags) != 0)
            return 0;
        err = _nfs4_do_setlk(state, F_SETLK, request, NFS_LOCK_RECLAIM);
        if (err != -NFS4ERR_DELAY)
            break;
        nfs4_handle_exception(server, err, &exception);
    } while (exception.retry);
    return err;
}

static int nfs4_lock_expired(struct nfs4_state *state, struct file_lock *request)
{
    struct nfs_server *server = NFS_SERVER(state->inode);
    struct nfs4_exception exception = {
        .inode = state->inode,
    };
    int err;

    err = nfs4_set_lock_state(state, request);
    if (err != 0)
        return err;
    do {
        if (test_bit(NFS_DELEGATED_STATE, &state->flags) != 0)
            return 0;
        err = _nfs4_do_setlk(state, F_SETLK, request, NFS_LOCK_EXPIRED);
        switch (err) {
        default:
            goto out;
        case -NFS4ERR_GRACE:
        case -NFS4ERR_DELAY:
            nfs4_handle_exception(server, err, &exception);
            err = 0;
        }
    } while (exception.retry);
out:
    return err;
}

#if defined(CONFIG_NFS_V4_1)

static int nfs41_check_expired_locks(struct nfs4_state *state)
{
    int status, ret = -NFS4ERR_BAD_STATEID;
    struct nfs4_lock_state *lsp;
    struct nfs_server *server = NFS_SERVER(state->inode);

    list_for_each_entry(lsp, &state->lock_states, ls_locks) {
        if (test_bit(NFS_LOCK_INITIALIZED, &lsp->ls_flags)) {
            status = nfs41_test_stateid(server, &lsp->ls_stateid);
            if (status != NFS_OK) {
                /* Free the stateid unless the server
                 * informs us the stateid is unrecognized. */
                if (status != -NFS4ERR_BAD_STATEID)
                    nfs41_free_stateid(server,
                            &lsp->ls_stateid);
                clear_bit(NFS_LOCK_INITIALIZED, &lsp->ls_flags);
                ret = status;
            }
        }
    };

    return ret;
}

static int nfs41_lock_expired(struct nfs4_state *state, struct file_lock *request)
{
    int status = NFS_OK;

    if (test_bit(LK_STATE_IN_USE, &state->flags))
        status = nfs41_check_expired_locks(state);
    if (status != NFS_OK)
        status = nfs4_lock_expired(state, request);
    return status;
}
#endif

static int _nfs4_proc_setlk(struct nfs4_state *state, int cmd, struct file_lock *request)
{
    struct nfs_inode *nfsi = NFS_I(state->inode);
    unsigned char fl_flags = request->fl_flags;
    int status = -ENOLCK;

    if ((fl_flags & FL_POSIX) &&
            !test_bit(NFS_STATE_POSIX_LOCKS, &state->flags))
        goto out;
    /* Is this a delegated open? */
    status = nfs4_set_lock_state(state, request);
    if (status != 0)
        goto out;
    request->fl_flags |= FL_ACCESS;
    status = do_vfs_lock(request->fl_file, request);
    if (status < 0)
        goto out;
    down_read(&nfsi->rwsem);
    if (test_bit(NFS_DELEGATED_STATE, &state->flags)) {
        /* Yes: cache locks! */
        /* ...but avoid races with delegation recall... */
        request->fl_flags = fl_flags & ~FL_SLEEP;
        status = do_vfs_lock(request->fl_file, request);
        goto out_unlock;
    }
    status = _nfs4_do_setlk(state, cmd, request, NFS_LOCK_NEW);
    if (status != 0)
        goto out_unlock;
    /* Note: we always want to sleep here! */
    request->fl_flags = fl_flags | FL_SLEEP;
    if (do_vfs_lock(request->fl_file, request) < 0)
        printk(KERN_WARNING "NFS: %s: VFS is out of sync with lock "
            "manager!\n", __func__);
out_unlock:
    up_read(&nfsi->rwsem);
out:
    request->fl_flags = fl_flags;
    return status;
}

static int nfs4_proc_setlk(struct nfs4_state *state, int cmd, struct file_lock *request)
{
    struct nfs4_exception exception = {
        .state = state,
        .inode = state->inode,
    };
    int err;

    do {
        err = _nfs4_proc_setlk(state, cmd, request);
        if (err == -NFS4ERR_DENIED)
            err = -EAGAIN;
        err = nfs4_handle_exception(NFS_SERVER(state->inode),
                err, &exception);
    } while (exception.retry);
    return err;
}

static int
nfs4_proc_lock(struct file *filp, int cmd, struct file_lock *request)
{
    struct nfs_open_context *ctx;
    struct nfs4_state *state;
    unsigned long timeout = NFS4_LOCK_MINTIMEOUT;
    int status;

    /* verify open state */
    ctx = nfs_file_open_context(filp);
    state = ctx->state;

    if (request->fl_start < 0 || request->fl_end < 0)
        return -EINVAL;

    if (IS_GETLK(cmd)) {
        if (state != NULL)
            return nfs4_proc_getlk(state, F_GETLK, request);
        return 0;
    }

    if (!(IS_SETLK(cmd) || IS_SETLKW(cmd)))
        return -EINVAL;

    if (request->fl_type == F_UNLCK) {
        if (state != NULL)
            return nfs4_proc_unlck(state, cmd, request);
        return 0;
    }

    if (state == NULL)
        return -ENOLCK;
    /*
     * Don't rely on the VFS having checked the file open mode,
     * since it won't do this for flock() locks.
     */
    switch (request->fl_type) {
    case F_RDLCK:
        if (!(filp->f_mode & FMODE_READ))
            return -EBADF;
        break;
    case F_WRLCK:
        if (!(filp->f_mode & FMODE_WRITE))
            return -EBADF;
    }

    do {
        status = nfs4_proc_setlk(state, cmd, request);
        if ((status != -EAGAIN) || IS_SETLK(cmd))
            break;
        timeout = nfs4_set_lock_task_retry(timeout);
        status = -ERESTARTSYS;
        if (signalled())
            break;
    } while(status < 0);
    return status;
}

int nfs4_lock_delegation_recall(struct nfs4_state *state, struct file_lock *fl)
{
    struct nfs_server *server = NFS_SERVER(state->inode);
    struct nfs4_exception exception = { };
    int err;

    err = nfs4_set_lock_state(state, fl);
    if (err != 0)
        goto out;
    do {
        err = _nfs4_do_setlk(state, F_SETLK, fl, NFS_LOCK_NEW);
        switch (err) {
            default:
                printk(KERN_ERR "NFS: %s: unhandled error "
                    "%d.\n", __func__, err);
            case 0:
            case -ESTALE:
                goto out;
            case -NFS4ERR_EXPIRED:
                nfs4_schedule_stateid_recovery(server, state);
            case -NFS4ERR_STALE_CLIENTID:
            case -NFS4ERR_STALE_STATEID:
                nfs4_schedule_lease_recovery(server->nfs_client);
                goto out;
            case -NFS4ERR_BADSESSION:
            case -NFS4ERR_BADSLOT:
            case -NFS4ERR_BAD_HIGH_SLOT:
            case -NFS4ERR_CONN_NOT_BOUND_TO_SESSION:
            case -NFS4ERR_DEADSESSION:
                nfs4_schedule_session_recovery(server->nfs_client->cl_session, err);
                goto out;
            case -ERESTARTSYS:
                /*
                 * The show must go on: exit, but mark the
                 * stateid as needing recovery.
                 */
            case -NFS4ERR_DELEG_REVOKED:
            case -NFS4ERR_ADMIN_REVOKED:
            case -NFS4ERR_BAD_STATEID:
            case -NFS4ERR_OPENMODE:
                nfs4_schedule_stateid_recovery(server, state);
                err = 0;
                goto out;
            case -EKEYEXPIRED:
                /*
                 * User RPCSEC_GSS context has expired.
                 * We cannot recover this stateid now, so
                 * skip it and allow recovery thread to
                 * proceed.
                 */
                err = 0;
                goto out;
            case -ENOMEM:
            case -NFS4ERR_DENIED:
                /* kill_proc(fl->fl_pid, SIGLOST, 1); */
                err = 0;
                goto out;
            case -NFS4ERR_DELAY:
                break;
        }
        err = nfs4_handle_exception(server, err, &exception);
    } while (exception.retry);
out:
    return err;
}

struct nfs_release_lockowner_data {
    struct nfs4_lock_state *lsp;
    struct nfs_server *server;
    struct nfs_release_lockowner_args args;
};

static void nfs4_release_lockowner_release(void *calldata)
{
    struct nfs_release_lockowner_data *data = calldata;
    nfs4_free_lock_state(data->server, data->lsp);
    kfree(calldata);
}

static const struct rpc_call_ops nfs4_release_lockowner_ops = {
    .rpc_release = nfs4_release_lockowner_release,
};

int nfs4_release_lockowner(struct nfs4_lock_state *lsp)
{
    struct nfs_server *server = lsp->ls_state->owner->so_server;
    struct nfs_release_lockowner_data *data;
    struct rpc_message msg = {
        .rpc_proc = &nfs4_procedures[NFSPROC4_CLNT_RELEASE_LOCKOWNER],
    };

    if (server->nfs_client->cl_mvops->minor_version != 0)
        return -EINVAL;
    data = kmalloc(sizeof(*data), GFP_NOFS);
    if (!data)
        return -ENOMEM;
    data->lsp = lsp;
    data->server = server;
    data->args.lock_owner.clientid = server->nfs_client->cl_clientid;
    data->args.lock_owner.id = lsp->ls_seqid.owner_id;
    data->args.lock_owner.s_dev = server->s_dev;
    msg.rpc_argp = &data->args;
    rpc_call_async(server->client, &msg, 0, &nfs4_release_lockowner_ops, data);
    return 0;
}

#define XATTR_NAME_NFSV4_ACL "system.nfs4_acl"

static int nfs4_xattr_set_nfs4_acl(struct dentry *dentry, const char *key,
                   const void *buf, size_t buflen,
                   int flags, int type)
{
    if (strcmp(key, "") != 0)
        return -EINVAL;

    return nfs4_proc_set_acl(dentry->d_inode, buf, buflen);
}

static int nfs4_xattr_get_nfs4_acl(struct dentry *dentry, const char *key,
                   void *buf, size_t buflen, int type)
{
    if (strcmp(key, "") != 0)
        return -EINVAL;

    return nfs4_proc_get_acl(dentry->d_inode, buf, buflen);
}

static size_t nfs4_xattr_list_nfs4_acl(struct dentry *dentry, char *list,
                       size_t list_len, const char *name,
                       size_t name_len, int type)
{
    size_t len = sizeof(XATTR_NAME_NFSV4_ACL);

    if (!nfs4_server_supports_acls(NFS_SERVER(dentry->d_inode)))
        return 0;

    if (list && len <= list_len)
        memcpy(list, XATTR_NAME_NFSV4_ACL, len);
    return len;
}

/*
 * nfs_fhget will use either the mounted_on_fileid or the fileid
 */
static void nfs_fixup_referral_attributes(struct nfs_fattr *fattr)
{
    if (!(((fattr->valid & NFS_ATTR_FATTR_MOUNTED_ON_FILEID) ||
           (fattr->valid & NFS_ATTR_FATTR_FILEID)) &&
          (fattr->valid & NFS_ATTR_FATTR_FSID) &&
          (fattr->valid & NFS_ATTR_FATTR_V4_LOCATIONS)))
        return;

    fattr->valid |= NFS_ATTR_FATTR_TYPE | NFS_ATTR_FATTR_MODE |
        NFS_ATTR_FATTR_NLINK | NFS_ATTR_FATTR_V4_REFERRAL;
    fattr->mode = S_IFDIR | S_IRUGO | S_IXUGO;
    fattr->nlink = 2;
}

static int _nfs4_proc_fs_locations(struct rpc_clnt *client, struct inode *dir,
                   const struct qstr *name,
                   struct nfs4_fs_locations *fs_locations,
                   struct page *page)
{
    struct nfs_server *server = NFS_SERVER(dir);
    u32 bitmask[2] = {
        [0] = FATTR4_WORD0_FSID | FATTR4_WORD0_FS_LOCATIONS,
    };
    struct nfs4_fs_locations_arg args = {
        .dir_fh = NFS_FH(dir),
        .name = name,
        .page = page,
        .bitmask = bitmask,
    };
    struct nfs4_fs_locations_res res = {
        .fs_locations = fs_locations,
    };
    struct rpc_message msg = {
        .rpc_proc = &nfs4_procedures[NFSPROC4_CLNT_FS_LOCATIONS],
        .rpc_argp = &args,
        .rpc_resp = &res,
    };
    int status;

    dprintk("%s: start\n", __func__);

    /* Ask for the fileid of the absent filesystem if mounted_on_fileid
     * is not supported */
    if (NFS_SERVER(dir)->attr_bitmask[1] & FATTR4_WORD1_MOUNTED_ON_FILEID)
        bitmask[1] |= FATTR4_WORD1_MOUNTED_ON_FILEID;
    else
        bitmask[0] |= FATTR4_WORD0_FILEID;

    nfs_fattr_init(&fs_locations->fattr);
    fs_locations->server = server;
    fs_locations->nlocations = 0;
    status = nfs4_call_sync(client, server, &msg, &args.seq_args, &res.seq_res, 0);
    dprintk("%s: returned status = %d\n", __func__, status);
    return status;
}

int nfs4_proc_fs_locations(struct rpc_clnt *client, struct inode *dir,
               const struct qstr *name,
               struct nfs4_fs_locations *fs_locations,
               struct page *page)
{
    struct nfs4_exception exception = { };
    int err;
    do {
        err = nfs4_handle_exception(NFS_SERVER(dir),
                _nfs4_proc_fs_locations(client, dir, name, fs_locations, page),
                &exception);
    } while (exception.retry);
    return err;
}

static int _nfs4_proc_secinfo(struct inode *dir, const struct qstr *name, struct nfs4_secinfo_flavors *flavors)
{
    int status;
    struct nfs4_secinfo_arg args = {
        .dir_fh = NFS_FH(dir),
        .name   = name,
    };
    struct nfs4_secinfo_res res = {
        .flavors     = flavors,
    };
    struct rpc_message msg = {
        .rpc_proc = &nfs4_procedures[NFSPROC4_CLNT_SECINFO],
        .rpc_argp = &args,
        .rpc_resp = &res,
    };

    dprintk("NFS call  secinfo %s\n", name->name);
    status = nfs4_call_sync(NFS_SERVER(dir)->client, NFS_SERVER(dir), &msg, &args.seq_args, &res.seq_res, 0);
    dprintk("NFS reply  secinfo: %d\n", status);
    return status;
}

int nfs4_proc_secinfo(struct inode *dir, const struct qstr *name,
              struct nfs4_secinfo_flavors *flavors)
{
    struct nfs4_exception exception = { };
    int err;
    do {
        err = nfs4_handle_exception(NFS_SERVER(dir),
                _nfs4_proc_secinfo(dir, name, flavors),
                &exception);
    } while (exception.retry);
    return err;
}

#ifdef CONFIG_NFS_V4_1
/*
 * Check the exchange flags returned by the server for invalid flags, having
 * both PNFS and NON_PNFS flags set, and not having one of NON_PNFS, PNFS, or
 * DS flags set.
 */
static int nfs4_check_cl_exchange_flags(u32 flags)
{
    if (flags & ~EXCHGID4_FLAG_MASK_R)
        goto out_inval;
    if ((flags & EXCHGID4_FLAG_USE_PNFS_MDS) &&
        (flags & EXCHGID4_FLAG_USE_NON_PNFS))
        goto out_inval;
    if (!(flags & (EXCHGID4_FLAG_MASK_PNFS)))
        goto out_inval;
    return NFS_OK;
out_inval:
    return -NFS4ERR_INVAL;
}

static bool
nfs41_same_server_scope(struct nfs41_server_scope *a,
            struct nfs41_server_scope *b)
{
    if (a->server_scope_sz == b->server_scope_sz &&
        memcmp(a->server_scope, b->server_scope, a->server_scope_sz) == 0)
        return true;

    return false;
}

/*
 * nfs4_proc_bind_conn_to_session()
 *
 * The 4.1 client currently uses the same TCP connection for the
 * fore and backchannel.
 */
int nfs4_proc_bind_conn_to_session(struct nfs_client *clp, struct rpc_cred *cred)
{
    int status;
    struct nfs41_bind_conn_to_session_res res;
    struct rpc_message msg = {
        .rpc_proc =
            &nfs4_procedures[NFSPROC4_CLNT_BIND_CONN_TO_SESSION],
        .rpc_argp = clp,
        .rpc_resp = &res,
        .rpc_cred = cred,
    };

    dprintk("--> %s\n", __func__);
    BUG_ON(clp == NULL);

    res.session = kzalloc(sizeof(struct nfs4_session), GFP_NOFS);
    if (unlikely(res.session == NULL)) {
        status = -ENOMEM;
        goto out;
    }

    status = rpc_call_sync(clp->cl_rpcclient, &msg, RPC_TASK_TIMEOUT);
    if (status == 0) {
        if (memcmp(res.session->sess_id.data,
            clp->cl_session->sess_id.data, NFS4_MAX_SESSIONID_LEN)) {
            dprintk("NFS: %s: Session ID mismatch\n", __func__);
            status = -EIO;
            goto out_session;
        }
        if (res.dir != NFS4_CDFS4_BOTH) {
            dprintk("NFS: %s: Unexpected direction from server\n",
                __func__);
            status = -EIO;
            goto out_session;
        }
        if (res.use_conn_in_rdma_mode) {
            dprintk("NFS: %s: Server returned RDMA mode = true\n",
                __func__);
            status = -EIO;
            goto out_session;
        }
    }
out_session:
    kfree(res.session);
out:
    dprintk("<-- %s status= %d\n", __func__, status);
    return status;
}

/*
 * nfs4_proc_exchange_id()
 *
 * Returns zero, a negative errno, or a negative NFS4ERR status code.
 *
 * Since the clientid has expired, all compounds using sessions
 * associated with the stale clientid will be returning
 * NFS4ERR_BADSESSION in the sequence operation, and will therefore
 * be in some phase of session reset.
 */
int nfs4_proc_exchange_id(struct nfs_client *clp, struct rpc_cred *cred)
{
    nfs4_verifier verifier;
    struct nfs41_exchange_id_args args = {
        .verifier = &verifier,
        .client = clp,
        .flags = EXCHGID4_FLAG_SUPP_MOVED_REFER,
    };
    struct nfs41_exchange_id_res res = {
        0
    };
    int status;
    struct rpc_message msg = {
        .rpc_proc = &nfs4_procedures[NFSPROC4_CLNT_EXCHANGE_ID],
        .rpc_argp = &args,
        .rpc_resp = &res,
        .rpc_cred = cred,
    };

    nfs4_init_boot_verifier(clp, &verifier);
    args.id_len = nfs4_init_uniform_client_string(clp, args.id,
                            sizeof(args.id));
    dprintk("NFS call  exchange_id auth=%s, '%.*s'\n",
        clp->cl_rpcclient->cl_auth->au_ops->au_name,
        args.id_len, args.id);

    res.server_owner = kzalloc(sizeof(struct nfs41_server_owner),
                    GFP_NOFS);
    if (unlikely(res.server_owner == NULL)) {
        status = -ENOMEM;
        goto out;
    }

    res.server_scope = kzalloc(sizeof(struct nfs41_server_scope),
                    GFP_NOFS);
    if (unlikely(res.server_scope == NULL)) {
        status = -ENOMEM;
        goto out_server_owner;
    }

    res.impl_id = kzalloc(sizeof(struct nfs41_impl_id), GFP_NOFS);
    if (unlikely(res.impl_id == NULL)) {
        status = -ENOMEM;
        goto out_server_scope;
    }

    status = rpc_call_sync(clp->cl_rpcclient, &msg, RPC_TASK_TIMEOUT);
    if (status == 0)
        status = nfs4_check_cl_exchange_flags(res.flags);

    if (status == 0) {
        clp->cl_clientid = res.clientid;
        clp->cl_exchange_flags = (res.flags & ~EXCHGID4_FLAG_CONFIRMED_R);
        if (!(res.flags & EXCHGID4_FLAG_CONFIRMED_R))
            clp->cl_seqid = res.seqid;

        kfree(clp->cl_serverowner);
        clp->cl_serverowner = res.server_owner;
        res.server_owner = NULL;

        /* use the most recent implementation id */
        kfree(clp->cl_implid);
        clp->cl_implid = res.impl_id;

        if (clp->cl_serverscope != NULL &&
            !nfs41_same_server_scope(clp->cl_serverscope,
                         res.server_scope)) {
            dprintk("%s: server_scope mismatch detected\n",
                __func__);
            set_bit(NFS4CLNT_SERVER_SCOPE_MISMATCH, &clp->cl_state);
            kfree(clp->cl_serverscope);
            clp->cl_serverscope = NULL;
        }

        if (clp->cl_serverscope == NULL) {
            clp->cl_serverscope = res.server_scope;
            goto out;
        }
    } else
        kfree(res.impl_id);

out_server_owner:
    kfree(res.server_owner);
out_server_scope:
    kfree(res.server_scope);
out:
    if (clp->cl_implid != NULL)
        dprintk("NFS reply exchange_id: Server Implementation ID: "
            "domain: %s, name: %s, date: %llu,%u\n",
            clp->cl_implid->domain, clp->cl_implid->name,
            clp->cl_implid->date.seconds,
            clp->cl_implid->date.nseconds);
    dprintk("NFS reply exchange_id: %d\n", status);
    return status;
}

static int _nfs4_proc_destroy_clientid(struct nfs_client *clp,
        struct rpc_cred *cred)
{
    struct rpc_message msg = {
        .rpc_proc = &nfs4_procedures[NFSPROC4_CLNT_DESTROY_CLIENTID],
        .rpc_argp = clp,
        .rpc_cred = cred,
    };
    int status;

    status = rpc_call_sync(clp->cl_rpcclient, &msg, RPC_TASK_TIMEOUT);
    if (status)
        dprintk("NFS: Got error %d from the server %s on "
            "DESTROY_CLIENTID.", status, clp->cl_hostname);
    return status;
}

static int nfs4_proc_destroy_clientid(struct nfs_client *clp,
        struct rpc_cred *cred)
{
    unsigned int loop;
    int ret;

    for (loop = NFS4_MAX_LOOP_ON_RECOVER; loop != 0; loop--) {
        ret = _nfs4_proc_destroy_clientid(clp, cred);
        switch (ret) {
        case -NFS4ERR_DELAY:
        case -NFS4ERR_CLIENTID_BUSY:
            ssleep(1);
            break;
        default:
            return ret;
        }
    }
    return 0;
}

int nfs4_destroy_clientid(struct nfs_client *clp)
{
    struct rpc_cred *cred;
    int ret = 0;

    if (clp->cl_mvops->minor_version < 1)
        goto out;
    if (clp->cl_exchange_flags == 0)
        goto out;
    if (clp->cl_preserve_clid)
        goto out;
    cred = nfs4_get_exchange_id_cred(clp);
    ret = nfs4_proc_destroy_clientid(clp, cred);
    if (cred)
        put_rpccred(cred);
    switch (ret) {
    case 0:
    case -NFS4ERR_STALE_CLIENTID:
        clp->cl_exchange_flags = 0;
    }
out:
    return ret;
}

struct nfs4_get_lease_time_data {
    struct nfs4_get_lease_time_args *args;
    struct nfs4_get_lease_time_res *res;
    struct nfs_client *clp;
};

static void nfs4_get_lease_time_prepare(struct rpc_task *task,
                    void *calldata)
{
    int ret;
    struct nfs4_get_lease_time_data *data =
            (struct nfs4_get_lease_time_data *)calldata;

    dprintk("--> %s\n", __func__);
    rpc_task_set_priority(task, RPC_PRIORITY_PRIVILEGED);
    /* just setup sequence, do not trigger session recovery
       since we're invoked within one */
    ret = nfs41_setup_sequence(data->clp->cl_session,
                   &data->args->la_seq_args,
                   &data->res->lr_seq_res, task);

    BUG_ON(ret == -EAGAIN);
    rpc_call_start(task);
    dprintk("<-- %s\n", __func__);
}

/*
 * Called from nfs4_state_manager thread for session setup, so don't recover
 * from sequence operation or clientid errors.
 */
static void nfs4_get_lease_time_done(struct rpc_task *task, void *calldata)
{
    struct nfs4_get_lease_time_data *data =
            (struct nfs4_get_lease_time_data *)calldata;

    dprintk("--> %s\n", __func__);
    if (!nfs41_sequence_done(task, &data->res->lr_seq_res))
        return;
    switch (task->tk_status) {
    case -NFS4ERR_DELAY:
    case -NFS4ERR_GRACE:
        dprintk("%s Retry: tk_status %d\n", __func__, task->tk_status);
        rpc_delay(task, NFS4_POLL_RETRY_MIN);
        task->tk_status = 0;
        /* fall through */
    case -NFS4ERR_RETRY_UNCACHED_REP:
        rpc_restart_call_prepare(task);
        return;
    }
    dprintk("<-- %s\n", __func__);
}

static const struct rpc_call_ops nfs4_get_lease_time_ops = {
    .rpc_call_prepare = nfs4_get_lease_time_prepare,
    .rpc_call_done = nfs4_get_lease_time_done,
};

int nfs4_proc_get_lease_time(struct nfs_client *clp, struct nfs_fsinfo *fsinfo)
{
    struct rpc_task *task;
    struct nfs4_get_lease_time_args args;
    struct nfs4_get_lease_time_res res = {
        .lr_fsinfo = fsinfo,
    };
    struct nfs4_get_lease_time_data data = {
        .args = &args,
        .res = &res,
        .clp = clp,
    };
    struct rpc_message msg = {
        .rpc_proc = &nfs4_procedures[NFSPROC4_CLNT_GET_LEASE_TIME],
        .rpc_argp = &args,
        .rpc_resp = &res,
    };
    struct rpc_task_setup task_setup = {
        .rpc_client = clp->cl_rpcclient,
        .rpc_message = &msg,
        .callback_ops = &nfs4_get_lease_time_ops,
        .callback_data = &data,
        .flags = RPC_TASK_TIMEOUT,
    };
    int status;

    nfs41_init_sequence(&args.la_seq_args, &res.lr_seq_res, 0);
    dprintk("--> %s\n", __func__);
    task = rpc_run_task(&task_setup);

    if (IS_ERR(task))
        status = PTR_ERR(task);
    else {
        status = task->tk_status;
        rpc_put_task(task);
    }
    dprintk("<-- %s return %d\n", __func__, status);

    return status;
}

static struct nfs4_slot *nfs4_alloc_slots(u32 max_slots, gfp_t gfp_flags)
{
    return kcalloc(max_slots, sizeof(struct nfs4_slot), gfp_flags);
}

static void nfs4_add_and_init_slots(struct nfs4_slot_table *tbl,
        struct nfs4_slot *new,
        u32 max_slots,
        u32 ivalue)
{
    struct nfs4_slot *old = NULL;
    u32 i;

    spin_lock(&tbl->slot_tbl_lock);
    if (new) {
        old = tbl->slots;
        tbl->slots = new;
        tbl->max_slots = max_slots;
    }
    tbl->highest_used_slotid = NFS4_NO_SLOT;
    for (i = 0; i < tbl->max_slots; i++)
        tbl->slots[i].seq_nr = ivalue;
    spin_unlock(&tbl->slot_tbl_lock);
    kfree(old);
}

/*
 * (re)Initialise a slot table
 */
static int nfs4_realloc_slot_table(struct nfs4_slot_table *tbl, u32 max_reqs,
                 u32 ivalue)
{
    struct nfs4_slot *new = NULL;
    int ret = -ENOMEM;

    dprintk("--> %s: max_reqs=%u, tbl->max_slots %d\n", __func__,
        max_reqs, tbl->max_slots);

    /* Does the newly negotiated max_reqs match the existing slot table? */
    if (max_reqs != tbl->max_slots) {
        new = nfs4_alloc_slots(max_reqs, GFP_NOFS);
        if (!new)
            goto out;
    }
    ret = 0;

    nfs4_add_and_init_slots(tbl, new, max_reqs, ivalue);
    dprintk("%s: tbl=%p slots=%p max_slots=%d\n", __func__,
        tbl, tbl->slots, tbl->max_slots);
out:
    dprintk("<-- %s: return %d\n", __func__, ret);
    return ret;
}

/* Destroy the slot table */
static void nfs4_destroy_slot_tables(struct nfs4_session *session)
{
    if (session->fc_slot_table.slots != NULL) {
        kfree(session->fc_slot_table.slots);
        session->fc_slot_table.slots = NULL;
    }
    if (session->bc_slot_table.slots != NULL) {
        kfree(session->bc_slot_table.slots);
        session->bc_slot_table.slots = NULL;
    }
    return;
}

/*
 * Initialize or reset the forechannel and backchannel tables
 */
static int nfs4_setup_session_slot_tables(struct nfs4_session *ses)
{
    struct nfs4_slot_table *tbl;
    int status;

    dprintk("--> %s\n", __func__);
    /* Fore channel */
    tbl = &ses->fc_slot_table;
    status = nfs4_realloc_slot_table(tbl, ses->fc_attrs.max_reqs, 1);
    if (status) /* -ENOMEM */
        return status;
    /* Back channel */
    tbl = &ses->bc_slot_table;
    status = nfs4_realloc_slot_table(tbl, ses->bc_attrs.max_reqs, 0);
    if (status && tbl->slots == NULL)
        /* Fore and back channel share a connection so get
         * both slot tables or neither */
        nfs4_destroy_slot_tables(ses);
    return status;
}

struct nfs4_session *nfs4_alloc_session(struct nfs_client *clp)
{
    struct nfs4_session *session;
    struct nfs4_slot_table *tbl;

    session = kzalloc(sizeof(struct nfs4_session), GFP_NOFS);
    if (!session)
        return NULL;

    tbl = &session->fc_slot_table;
    tbl->highest_used_slotid = NFS4_NO_SLOT;
    spin_lock_init(&tbl->slot_tbl_lock);
    rpc_init_priority_wait_queue(&tbl->slot_tbl_waitq, "ForeChannel Slot table");
    init_completion(&tbl->complete);

    tbl = &session->bc_slot_table;
    tbl->highest_used_slotid = NFS4_NO_SLOT;
    spin_lock_init(&tbl->slot_tbl_lock);
    rpc_init_wait_queue(&tbl->slot_tbl_waitq, "BackChannel Slot table");
    init_completion(&tbl->complete);

    session->session_state = 1<<NFS4_SESSION_INITING;

    session->clp = clp;
    return session;
}

void nfs4_destroy_session(struct nfs4_session *session)
{
    struct rpc_xprt *xprt;
    struct rpc_cred *cred;

    cred = nfs4_get_exchange_id_cred(session->clp);
    nfs4_proc_destroy_session(session, cred);
    if (cred)
        put_rpccred(cred);

    rcu_read_lock();
    xprt = rcu_dereference(session->clp->cl_rpcclient->cl_xprt);
    rcu_read_unlock();
    dprintk("%s Destroy backchannel for xprt %p\n",
        __func__, xprt);
    xprt_destroy_backchannel(xprt, NFS41_BC_MIN_CALLBACKS);
    nfs4_destroy_slot_tables(session);
    kfree(session);
}

/*
 * Initialize the values to be used by the client in CREATE_SESSION
 * If nfs4_init_session set the fore channel request and response sizes,
 * use them.
 *
 * Set the back channel max_resp_sz_cached to zero to force the client to
 * always set csa_cachethis to FALSE because the current implementation
 * of the back channel DRC only supports caching the CB_SEQUENCE operation.
 */
static void nfs4_init_channel_attrs(struct nfs41_create_session_args *args)
{
    struct nfs4_session *session = args->client->cl_session;
    unsigned int mxrqst_sz = session->fc_attrs.max_rqst_sz,
             mxresp_sz = session->fc_attrs.max_resp_sz;

    if (mxrqst_sz == 0)
        mxrqst_sz = NFS_MAX_FILE_IO_SIZE;
    if (mxresp_sz == 0)
        mxresp_sz = NFS_MAX_FILE_IO_SIZE;
    /* Fore channel attributes */
    args->fc_attrs.max_rqst_sz = mxrqst_sz;
    args->fc_attrs.max_resp_sz = mxresp_sz;
    args->fc_attrs.max_ops = NFS4_MAX_OPS;
    args->fc_attrs.max_reqs = max_session_slots;

    dprintk("%s: Fore Channel : max_rqst_sz=%u max_resp_sz=%u "
        "max_ops=%u max_reqs=%u\n",
        __func__,
        args->fc_attrs.max_rqst_sz, args->fc_attrs.max_resp_sz,
        args->fc_attrs.max_ops, args->fc_attrs.max_reqs);

    /* Back channel attributes */
    args->bc_attrs.max_rqst_sz = PAGE_SIZE;
    args->bc_attrs.max_resp_sz = PAGE_SIZE;
    args->bc_attrs.max_resp_sz_cached = 0;
    args->bc_attrs.max_ops = NFS4_MAX_BACK_CHANNEL_OPS;
    args->bc_attrs.max_reqs = 1;

    dprintk("%s: Back Channel : max_rqst_sz=%u max_resp_sz=%u "
        "max_resp_sz_cached=%u max_ops=%u max_reqs=%u\n",
        __func__,
        args->bc_attrs.max_rqst_sz, args->bc_attrs.max_resp_sz,
        args->bc_attrs.max_resp_sz_cached, args->bc_attrs.max_ops,
        args->bc_attrs.max_reqs);
}

static int nfs4_verify_fore_channel_attrs(struct nfs41_create_session_args *args, struct nfs4_session *session)
{
    struct nfs4_channel_attrs *sent = &args->fc_attrs;
    struct nfs4_channel_attrs *rcvd = &session->fc_attrs;

    if (rcvd->max_resp_sz > sent->max_resp_sz)
        return -EINVAL;
    /*
     * Our requested max_ops is the minimum we need; we're not
     * prepared to break up compounds into smaller pieces than that.
     * So, no point even trying to continue if the server won't
     * cooperate:
     */
    if (rcvd->max_ops < sent->max_ops)
        return -EINVAL;
    if (rcvd->max_reqs == 0)
        return -EINVAL;
    if (rcvd->max_reqs > NFS4_MAX_SLOT_TABLE)
        rcvd->max_reqs = NFS4_MAX_SLOT_TABLE;
    return 0;
}

static int nfs4_verify_back_channel_attrs(struct nfs41_create_session_args *args, struct nfs4_session *session)
{
    struct nfs4_channel_attrs *sent = &args->bc_attrs;
    struct nfs4_channel_attrs *rcvd = &session->bc_attrs;

    if (rcvd->max_rqst_sz > sent->max_rqst_sz)
        return -EINVAL;
    if (rcvd->max_resp_sz < sent->max_resp_sz)
        return -EINVAL;
    if (rcvd->max_resp_sz_cached > sent->max_resp_sz_cached)
        return -EINVAL;
    /* These would render the backchannel useless: */
    if (rcvd->max_ops != sent->max_ops)
        return -EINVAL;
    if (rcvd->max_reqs != sent->max_reqs)
        return -EINVAL;
    return 0;
}

static int nfs4_verify_channel_attrs(struct nfs41_create_session_args *args,
                     struct nfs4_session *session)
{
    int ret;

    ret = nfs4_verify_fore_channel_attrs(args, session);
    if (ret)
        return ret;
    return nfs4_verify_back_channel_attrs(args, session);
}

static int _nfs4_proc_create_session(struct nfs_client *clp,
        struct rpc_cred *cred)
{
    struct nfs4_session *session = clp->cl_session;
    struct nfs41_create_session_args args = {
        .client = clp,
        .cb_program = NFS4_CALLBACK,
    };
    struct nfs41_create_session_res res = {
        .client = clp,
    };
    struct rpc_message msg = {
        .rpc_proc = &nfs4_procedures[NFSPROC4_CLNT_CREATE_SESSION],
        .rpc_argp = &args,
        .rpc_resp = &res,
        .rpc_cred = cred,
    };
    int status;

    nfs4_init_channel_attrs(&args);
    args.flags = (SESSION4_PERSIST | SESSION4_BACK_CHAN);

    status = rpc_call_sync(session->clp->cl_rpcclient, &msg, RPC_TASK_TIMEOUT);

    if (!status)
        /* Verify the session's negotiated channel_attrs values */
        status = nfs4_verify_channel_attrs(&args, session);
    if (!status) {
        /* Increment the clientid slot sequence id */
        clp->cl_seqid++;
    }

    return status;
}

/*
 * Issues a CREATE_SESSION operation to the server.
 * It is the responsibility of the caller to verify the session is
 * expired before calling this routine.
 */
int nfs4_proc_create_session(struct nfs_client *clp, struct rpc_cred *cred)
{
    int status;
    unsigned *ptr;
    struct nfs4_session *session = clp->cl_session;

    dprintk("--> %s clp=%p session=%p\n", __func__, clp, session);

    status = _nfs4_proc_create_session(clp, cred);
    if (status)
        goto out;

    /* Init or reset the session slot tables */
    status = nfs4_setup_session_slot_tables(session);
    dprintk("slot table setup returned %d\n", status);
    if (status)
        goto out;

    ptr = (unsigned *)&session->sess_id.data[0];
    dprintk("%s client>seqid %d sessionid %u:%u:%u:%u\n", __func__,
        clp->cl_seqid, ptr[0], ptr[1], ptr[2], ptr[3]);
out:
    dprintk("<-- %s\n", __func__);
    return status;
}

/*
 * Issue the over-the-wire RPC DESTROY_SESSION.
 * The caller must serialize access to this routine.
 */
int nfs4_proc_destroy_session(struct nfs4_session *session,
        struct rpc_cred *cred)
{
    struct rpc_message msg = {
        .rpc_proc = &nfs4_procedures[NFSPROC4_CLNT_DESTROY_SESSION],
        .rpc_argp = session,
        .rpc_cred = cred,
    };
    int status = 0;

    dprintk("--> nfs4_proc_destroy_session\n");

    /* session is still being setup */
    if (session->clp->cl_cons_state != NFS_CS_READY)
        return status;

    status = rpc_call_sync(session->clp->cl_rpcclient, &msg, RPC_TASK_TIMEOUT);

    if (status)
        dprintk("NFS: Got error %d from the server on DESTROY_SESSION. "
            "Session has been destroyed regardless...\n", status);

    dprintk("<-- nfs4_proc_destroy_session\n");
    return status;
}

/*
 * With sessions, the client is not marked ready until after a
 * successful EXCHANGE_ID and CREATE_SESSION.
 *
 * Map errors cl_cons_state errors to EPROTONOSUPPORT to indicate
 * other versions of NFS can be tried.
 */
static int nfs41_check_session_ready(struct nfs_client *clp)
{
    int ret;
    
    if (clp->cl_cons_state == NFS_CS_SESSION_INITING) {
        ret = nfs4_client_recover_expired_lease(clp);
        if (ret)
            return ret;
    }
    if (clp->cl_cons_state < NFS_CS_READY)
        return -EPROTONOSUPPORT;
    smp_rmb();
    return 0;
}

int nfs4_init_session(struct nfs_server *server)
{
    struct nfs_client *clp = server->nfs_client;
    struct nfs4_session *session;
    unsigned int rsize, wsize;

    if (!nfs4_has_session(clp))
        return 0;

    session = clp->cl_session;
    spin_lock(&clp->cl_lock);
    if (test_and_clear_bit(NFS4_SESSION_INITING, &session->session_state)) {

        rsize = server->rsize;
        if (rsize == 0)
            rsize = NFS_MAX_FILE_IO_SIZE;
        wsize = server->wsize;
        if (wsize == 0)
            wsize = NFS_MAX_FILE_IO_SIZE;

        session->fc_attrs.max_rqst_sz = wsize + nfs41_maxwrite_overhead;
        session->fc_attrs.max_resp_sz = rsize + nfs41_maxread_overhead;
    }
    spin_unlock(&clp->cl_lock);

    return nfs41_check_session_ready(clp);
}

int nfs4_init_ds_session(struct nfs_client *clp, unsigned long lease_time)
{
    struct nfs4_session *session = clp->cl_session;
    int ret;

    spin_lock(&clp->cl_lock);
    if (test_and_clear_bit(NFS4_SESSION_INITING, &session->session_state)) {
        /*
         * Do not set NFS_CS_CHECK_LEASE_TIME instead set the
         * DS lease to be equal to the MDS lease.
         */
        clp->cl_lease_time = lease_time;
        clp->cl_last_renewal = jiffies;
    }
    spin_unlock(&clp->cl_lock);

    ret = nfs41_check_session_ready(clp);
    if (ret)
        return ret;
    /* Test for the DS role */
    if (!is_ds_client(clp))
        return -ENODEV;
    return 0;
}
EXPORT_SYMBOL_GPL(nfs4_init_ds_session);


/*
 * Renew the cl_session lease.
 */
struct nfs4_sequence_data {
    struct nfs_client *clp;
    struct nfs4_sequence_args args;
    struct nfs4_sequence_res res;
};

static void nfs41_sequence_release(void *data)
{
    struct nfs4_sequence_data *calldata = data;
    struct nfs_client *clp = calldata->clp;

    if (atomic_read(&clp->cl_count) > 1)
        nfs4_schedule_state_renewal(clp);
    nfs_put_client(clp);
    kfree(calldata);
}

static int nfs41_sequence_handle_errors(struct rpc_task *task, struct nfs_client *clp)
{
    switch(task->tk_status) {
    case -NFS4ERR_DELAY:
        rpc_delay(task, NFS4_POLL_RETRY_MAX);
        return -EAGAIN;
    default:
        nfs4_schedule_lease_recovery(clp);
    }
    return 0;
}

static void nfs41_sequence_call_done(struct rpc_task *task, void *data)
{
    struct nfs4_sequence_data *calldata = data;
    struct nfs_client *clp = calldata->clp;

    if (!nfs41_sequence_done(task, task->tk_msg.rpc_resp))
        return;

    if (task->tk_status < 0) {
        dprintk("%s ERROR %d\n", __func__, task->tk_status);
        if (atomic_read(&clp->cl_count) == 1)
            goto out;

        if (nfs41_sequence_handle_errors(task, clp) == -EAGAIN) {
            rpc_restart_call_prepare(task);
            return;
        }
    }
    dprintk("%s rpc_cred %p\n", __func__, task->tk_msg.rpc_cred);
out:
    dprintk("<-- %s\n", __func__);
}

static void nfs41_sequence_prepare(struct rpc_task *task, void *data)
{
    struct nfs4_sequence_data *calldata = data;
    struct nfs_client *clp = calldata->clp;
    struct nfs4_sequence_args *args;
    struct nfs4_sequence_res *res;

    args = task->tk_msg.rpc_argp;
    res = task->tk_msg.rpc_resp;

    if (nfs41_setup_sequence(clp->cl_session, args, res, task))
        return;
    rpc_call_start(task);
}

static const struct rpc_call_ops nfs41_sequence_ops = {
    .rpc_call_done = nfs41_sequence_call_done,
    .rpc_call_prepare = nfs41_sequence_prepare,
    .rpc_release = nfs41_sequence_release,
};

static struct rpc_task *_nfs41_proc_sequence(struct nfs_client *clp, struct rpc_cred *cred)
{
    struct nfs4_sequence_data *calldata;
    struct rpc_message msg = {
        .rpc_proc = &nfs4_procedures[NFSPROC4_CLNT_SEQUENCE],
        .rpc_cred = cred,
    };
    struct rpc_task_setup task_setup_data = {
        .rpc_client = clp->cl_rpcclient,
        .rpc_message = &msg,
        .callback_ops = &nfs41_sequence_ops,
        .flags = RPC_TASK_ASYNC | RPC_TASK_SOFT,
    };

    if (!atomic_inc_not_zero(&clp->cl_count))
        return ERR_PTR(-EIO);
    calldata = kzalloc(sizeof(*calldata), GFP_NOFS);
    if (calldata == NULL) {
        nfs_put_client(clp);
        return ERR_PTR(-ENOMEM);
    }
    nfs41_init_sequence(&calldata->args, &calldata->res, 0);
    msg.rpc_argp = &calldata->args;
    msg.rpc_resp = &calldata->res;
    calldata->clp = clp;
    task_setup_data.callback_data = calldata;

    return rpc_run_task(&task_setup_data);
}

static int nfs41_proc_async_sequence(struct nfs_client *clp, struct rpc_cred *cred, unsigned renew_flags)
{
    struct rpc_task *task;
    int ret = 0;

    if ((renew_flags & NFS4_RENEW_TIMEOUT) == 0)
        return 0;
    task = _nfs41_proc_sequence(clp, cred);
    if (IS_ERR(task))
        ret = PTR_ERR(task);
    else
        rpc_put_task_async(task);
    dprintk("<-- %s status=%d\n", __func__, ret);
    return ret;
}

static int nfs4_proc_sequence(struct nfs_client *clp, struct rpc_cred *cred)
{
    struct rpc_task *task;
    int ret;

    task = _nfs41_proc_sequence(clp, cred);
    if (IS_ERR(task)) {
        ret = PTR_ERR(task);
        goto out;
    }
    ret = rpc_wait_for_completion_task(task);
    if (!ret) {
        struct nfs4_sequence_res *res = task->tk_msg.rpc_resp;

        if (task->tk_status == 0)
            nfs41_handle_sequence_flag_errors(clp, res->sr_status_flags);
        ret = task->tk_status;
    }
    rpc_put_task(task);
out:
    dprintk("<-- %s status=%d\n", __func__, ret);
    return ret;
}

struct nfs4_reclaim_complete_data {
    struct nfs_client *clp;
    struct nfs41_reclaim_complete_args arg;
    struct nfs41_reclaim_complete_res res;
};

static void nfs4_reclaim_complete_prepare(struct rpc_task *task, void *data)
{
    struct nfs4_reclaim_complete_data *calldata = data;

    rpc_task_set_priority(task, RPC_PRIORITY_PRIVILEGED);
    if (nfs41_setup_sequence(calldata->clp->cl_session,
                &calldata->arg.seq_args,
                &calldata->res.seq_res, task))
        return;

    rpc_call_start(task);
}

static int nfs41_reclaim_complete_handle_errors(struct rpc_task *task, struct nfs_client *clp)
{
    switch(task->tk_status) {
    case 0:
    case -NFS4ERR_COMPLETE_ALREADY:
    case -NFS4ERR_WRONG_CRED: /* What to do here? */
        break;
    case -NFS4ERR_DELAY:
        rpc_delay(task, NFS4_POLL_RETRY_MAX);
        /* fall through */
    case -NFS4ERR_RETRY_UNCACHED_REP:
        return -EAGAIN;
    default:
        nfs4_schedule_lease_recovery(clp);
    }
    return 0;
}

static void nfs4_reclaim_complete_done(struct rpc_task *task, void *data)
{
    struct nfs4_reclaim_complete_data *calldata = data;
    struct nfs_client *clp = calldata->clp;
    struct nfs4_sequence_res *res = &calldata->res.seq_res;

    dprintk("--> %s\n", __func__);
    if (!nfs41_sequence_done(task, res))
        return;

    if (nfs41_reclaim_complete_handle_errors(task, clp) == -EAGAIN) {
        rpc_restart_call_prepare(task);
        return;
    }
    dprintk("<-- %s\n", __func__);
}

static void nfs4_free_reclaim_complete_data(void *data)
{
    struct nfs4_reclaim_complete_data *calldata = data;

    kfree(calldata);
}

static const struct rpc_call_ops nfs4_reclaim_complete_call_ops = {
    .rpc_call_prepare = nfs4_reclaim_complete_prepare,
    .rpc_call_done = nfs4_reclaim_complete_done,
    .rpc_release = nfs4_free_reclaim_complete_data,
};

/*
 * Issue a global reclaim complete.
 */
static int nfs41_proc_reclaim_complete(struct nfs_client *clp)
{
    struct nfs4_reclaim_complete_data *calldata;
    struct rpc_task *task;
    struct rpc_message msg = {
        .rpc_proc = &nfs4_procedures[NFSPROC4_CLNT_RECLAIM_COMPLETE],
    };
    struct rpc_task_setup task_setup_data = {
        .rpc_client = clp->cl_rpcclient,
        .rpc_message = &msg,
        .callback_ops = &nfs4_reclaim_complete_call_ops,
        .flags = RPC_TASK_ASYNC,
    };
    int status = -ENOMEM;

    dprintk("--> %s\n", __func__);
    calldata = kzalloc(sizeof(*calldata), GFP_NOFS);
    if (calldata == NULL)
        goto out;
    calldata->clp = clp;
    calldata->arg.one_fs = 0;

    nfs41_init_sequence(&calldata->arg.seq_args, &calldata->res.seq_res, 0);
    msg.rpc_argp = &calldata->arg;
    msg.rpc_resp = &calldata->res;
    task_setup_data.callback_data = calldata;
    task = rpc_run_task(&task_setup_data);
    if (IS_ERR(task)) {
        status = PTR_ERR(task);
        goto out;
    }
    status = nfs4_wait_for_completion_rpc_task(task);
    if (status == 0)
        status = task->tk_status;
    rpc_put_task(task);
    return 0;
out:
    dprintk("<-- %s status=%d\n", __func__, status);
    return status;
}

static void
nfs4_layoutget_prepare(struct rpc_task *task, void *calldata)
{
    struct nfs4_layoutget *lgp = calldata;
    struct nfs_server *server = NFS_SERVER(lgp->args.inode);

    dprintk("--> %s\n", __func__);
    /* Note the is a race here, where a CB_LAYOUTRECALL can come in
     * right now covering the LAYOUTGET we are about to send.
     * However, that is not so catastrophic, and there seems
     * to be no way to prevent it completely.
     */
    if (nfs4_setup_sequence(server, &lgp->args.seq_args,
                &lgp->res.seq_res, task))
        return;
    if (pnfs_choose_layoutget_stateid(&lgp->args.stateid,
                      NFS_I(lgp->args.inode)->layout,
                      lgp->args.ctx->state)) {
        rpc_exit(task, NFS4_OK);
        return;
    }
    rpc_call_start(task);
}

static void nfs4_layoutget_done(struct rpc_task *task, void *calldata)
{
    struct nfs4_layoutget *lgp = calldata;
    struct inode *inode = lgp->args.inode;
    struct nfs_server *server = NFS_SERVER(inode);
    struct pnfs_layout_hdr *lo;
    struct nfs4_state *state = NULL;

    dprintk("--> %s\n", __func__);

    if (!nfs4_sequence_done(task, &lgp->res.seq_res))
        goto out;

    switch (task->tk_status) {
    case 0:
        goto out;
    case -NFS4ERR_LAYOUTTRYLATER:
    case -NFS4ERR_RECALLCONFLICT:
        task->tk_status = -NFS4ERR_DELAY;
        break;
    case -NFS4ERR_EXPIRED:
    case -NFS4ERR_BAD_STATEID:
        spin_lock(&inode->i_lock);
        lo = NFS_I(inode)->layout;
        if (!lo || list_empty(&lo->plh_segs)) {
            spin_unlock(&inode->i_lock);
            /* If the open stateid was bad, then recover it. */
            state = lgp->args.ctx->state;
        } else {
            LIST_HEAD(head);

            pnfs_mark_matching_lsegs_invalid(lo, &head, NULL);
            spin_unlock(&inode->i_lock);
            /* Mark the bad layout state as invalid, then
             * retry using the open stateid. */
            pnfs_free_lseg_list(&head);
        }
    }
    if (nfs4_async_handle_error(task, server, state) == -EAGAIN)
        rpc_restart_call_prepare(task);
out:
    dprintk("<-- %s\n", __func__);
}

static size_t max_response_pages(struct nfs_server *server)
{
    u32 max_resp_sz = server->nfs_client->cl_session->fc_attrs.max_resp_sz;
    return nfs_page_array_len(0, max_resp_sz);
}

static void nfs4_free_pages(struct page **pages, size_t size)
{
    int i;

    if (!pages)
        return;

    for (i = 0; i < size; i++) {
        if (!pages[i])
            break;
        __free_page(pages[i]);
    }
    kfree(pages);
}

static struct page **nfs4_alloc_pages(size_t size, gfp_t gfp_flags)
{
    struct page **pages;
    int i;

    pages = kcalloc(size, sizeof(struct page *), gfp_flags);
    if (!pages) {
        dprintk("%s: can't alloc array of %zu pages\n", __func__, size);
        return NULL;
    }

    for (i = 0; i < size; i++) {
        pages[i] = alloc_page(gfp_flags);
        if (!pages[i]) {
            dprintk("%s: failed to allocate page\n", __func__);
            nfs4_free_pages(pages, size);
            return NULL;
        }
    }

    return pages;
}

static void nfs4_layoutget_release(void *calldata)
{
    struct nfs4_layoutget *lgp = calldata;
    struct nfs_server *server = NFS_SERVER(lgp->args.inode);
    size_t max_pages = max_response_pages(server);

    dprintk("--> %s\n", __func__);
    nfs4_free_pages(lgp->args.layout.pages, max_pages);
    put_nfs_open_context(lgp->args.ctx);
    kfree(calldata);
    dprintk("<-- %s\n", __func__);
}

static const struct rpc_call_ops nfs4_layoutget_call_ops = {
    .rpc_call_prepare = nfs4_layoutget_prepare,
    .rpc_call_done = nfs4_layoutget_done,
    .rpc_release = nfs4_layoutget_release,
};

struct pnfs_layout_segment *
nfs4_proc_layoutget(struct nfs4_layoutget *lgp, gfp_t gfp_flags)
{
    struct nfs_server *server = NFS_SERVER(lgp->args.inode);
    size_t max_pages = max_response_pages(server);
    struct rpc_task *task;
    struct rpc_message msg = {
        .rpc_proc = &nfs4_procedures[NFSPROC4_CLNT_LAYOUTGET],
        .rpc_argp = &lgp->args,
        .rpc_resp = &lgp->res,
    };
    struct rpc_task_setup task_setup_data = {
        .rpc_client = server->client,
        .rpc_message = &msg,
        .callback_ops = &nfs4_layoutget_call_ops,
        .callback_data = lgp,
        .flags = RPC_TASK_ASYNC,
    };
    struct pnfs_layout_segment *lseg = NULL;
    int status = 0;

    dprintk("--> %s\n", __func__);

    lgp->args.layout.pages = nfs4_alloc_pages(max_pages, gfp_flags);
    if (!lgp->args.layout.pages) {
        nfs4_layoutget_release(lgp);
        return ERR_PTR(-ENOMEM);
    }
    lgp->args.layout.pglen = max_pages * PAGE_SIZE;

    lgp->res.layoutp = &lgp->args.layout;
    lgp->res.seq_res.sr_slot = NULL;
    nfs41_init_sequence(&lgp->args.seq_args, &lgp->res.seq_res, 0);
    task = rpc_run_task(&task_setup_data);
    if (IS_ERR(task))
        return ERR_CAST(task);
    status = nfs4_wait_for_completion_rpc_task(task);
    if (status == 0)
        status = task->tk_status;
    if (status == 0)
        lseg = pnfs_layout_process(lgp);
    rpc_put_task(task);
    dprintk("<-- %s status=%d\n", __func__, status);
    if (status)
        return ERR_PTR(status);
    return lseg;
}

static void
nfs4_layoutreturn_prepare(struct rpc_task *task, void *calldata)
{
    struct nfs4_layoutreturn *lrp = calldata;

    dprintk("--> %s\n", __func__);
    if (nfs41_setup_sequence(lrp->clp->cl_session, &lrp->args.seq_args,
                &lrp->res.seq_res, task))
        return;
    rpc_call_start(task);
}

static void nfs4_layoutreturn_done(struct rpc_task *task, void *calldata)
{
    struct nfs4_layoutreturn *lrp = calldata;
    struct nfs_server *server;

    dprintk("--> %s\n", __func__);

    if (!nfs4_sequence_done(task, &lrp->res.seq_res))
        return;

    server = NFS_SERVER(lrp->args.inode);
    if (nfs4_async_handle_error(task, server, NULL) == -EAGAIN) {
        rpc_restart_call_prepare(task);
        return;
    }
    dprintk("<-- %s\n", __func__);
}

static void nfs4_layoutreturn_release(void *calldata)
{
    struct nfs4_layoutreturn *lrp = calldata;
    struct pnfs_layout_hdr *lo = lrp->args.layout;

    dprintk("--> %s\n", __func__);
    spin_lock(&lo->plh_inode->i_lock);
    if (lrp->res.lrs_present)
        pnfs_set_layout_stateid(lo, &lrp->res.stateid, true);
    lo->plh_block_lgets--;
    spin_unlock(&lo->plh_inode->i_lock);
    pnfs_put_layout_hdr(lrp->args.layout);
    kfree(calldata);
    dprintk("<-- %s\n", __func__);
}

static const struct rpc_call_ops nfs4_layoutreturn_call_ops = {
    .rpc_call_prepare = nfs4_layoutreturn_prepare,
    .rpc_call_done = nfs4_layoutreturn_done,
    .rpc_release = nfs4_layoutreturn_release,
};

int nfs4_proc_layoutreturn(struct nfs4_layoutreturn *lrp)
{
    struct rpc_task *task;
    struct rpc_message msg = {
        .rpc_proc = &nfs4_procedures[NFSPROC4_CLNT_LAYOUTRETURN],
        .rpc_argp = &lrp->args,
        .rpc_resp = &lrp->res,
    };
    struct rpc_task_setup task_setup_data = {
        .rpc_client = lrp->clp->cl_rpcclient,
        .rpc_message = &msg,
        .callback_ops = &nfs4_layoutreturn_call_ops,
        .callback_data = lrp,
    };
    int status;

    dprintk("--> %s\n", __func__);
    nfs41_init_sequence(&lrp->args.seq_args, &lrp->res.seq_res, 1);
    task = rpc_run_task(&task_setup_data);
    if (IS_ERR(task))
        return PTR_ERR(task);
    status = task->tk_status;
    dprintk("<-- %s status=%d\n", __func__, status);
    rpc_put_task(task);
    return status;
}

/*
 * Retrieve the list of Data Server devices from the MDS.
 */
static int _nfs4_getdevicelist(struct nfs_server *server,
                    const struct nfs_fh *fh,
                    struct pnfs_devicelist *devlist)
{
    struct nfs4_getdevicelist_args args = {
        .fh = fh,
        .layoutclass = server->pnfs_curr_ld->id,
    };
    struct nfs4_getdevicelist_res res = {
        .devlist = devlist,
    };
    struct rpc_message msg = {
        .rpc_proc = &nfs4_procedures[NFSPROC4_CLNT_GETDEVICELIST],
        .rpc_argp = &args,
        .rpc_resp = &res,
    };
    int status;

    dprintk("--> %s\n", __func__);
    status = nfs4_call_sync(server->client, server, &msg, &args.seq_args,
                &res.seq_res, 0);
    dprintk("<-- %s status=%d\n", __func__, status);
    return status;
}

int nfs4_proc_getdevicelist(struct nfs_server *server,
                const struct nfs_fh *fh,
                struct pnfs_devicelist *devlist)
{
    struct nfs4_exception exception = { };
    int err;

    do {
        err = nfs4_handle_exception(server,
                _nfs4_getdevicelist(server, fh, devlist),
                &exception);
    } while (exception.retry);

    dprintk("%s: err=%d, num_devs=%u\n", __func__,
        err, devlist->num_devs);

    return err;
}
EXPORT_SYMBOL_GPL(nfs4_proc_getdevicelist);

static int
_nfs4_proc_getdeviceinfo(struct nfs_server *server, struct pnfs_device *pdev)
{
    struct nfs4_getdeviceinfo_args args = {
        .pdev = pdev,
    };
    struct nfs4_getdeviceinfo_res res = {
        .pdev = pdev,
    };
    struct rpc_message msg = {
        .rpc_proc = &nfs4_procedures[NFSPROC4_CLNT_GETDEVICEINFO],
        .rpc_argp = &args,
        .rpc_resp = &res,
    };
    int status;

    dprintk("--> %s\n", __func__);
    status = nfs4_call_sync(server->client, server, &msg, &args.seq_args, &res.seq_res, 0);
    dprintk("<-- %s status=%d\n", __func__, status);

    return status;
}

int nfs4_proc_getdeviceinfo(struct nfs_server *server, struct pnfs_device *pdev)
{
    struct nfs4_exception exception = { };
    int err;

    do {
        err = nfs4_handle_exception(server,
                    _nfs4_proc_getdeviceinfo(server, pdev),
                    &exception);
    } while (exception.retry);
    return err;
}
EXPORT_SYMBOL_GPL(nfs4_proc_getdeviceinfo);

static void nfs4_layoutcommit_prepare(struct rpc_task *task, void *calldata)
{
    struct nfs4_layoutcommit_data *data = calldata;
    struct nfs_server *server = NFS_SERVER(data->args.inode);

    if (nfs4_setup_sequence(server, &data->args.seq_args,
                &data->res.seq_res, task))
        return;
    rpc_call_start(task);
}

static void
nfs4_layoutcommit_done(struct rpc_task *task, void *calldata)
{
    struct nfs4_layoutcommit_data *data = calldata;
    struct nfs_server *server = NFS_SERVER(data->args.inode);

    if (!nfs4_sequence_done(task, &data->res.seq_res))
        return;

    switch (task->tk_status) { /* Just ignore these failures */
    case -NFS4ERR_DELEG_REVOKED: /* layout was recalled */
    case -NFS4ERR_BADIOMODE:     /* no IOMODE_RW layout for range */
    case -NFS4ERR_BADLAYOUT:     /* no layout */
    case -NFS4ERR_GRACE:        /* loca_recalim always false */
        task->tk_status = 0;
        break;
    case 0:
        nfs_post_op_update_inode_force_wcc(data->args.inode,
                           data->res.fattr);
        break;
    default:
        if (nfs4_async_handle_error(task, server, NULL) == -EAGAIN) {
            rpc_restart_call_prepare(task);
            return;
        }
    }
}

static void nfs4_layoutcommit_release(void *calldata)
{
    struct nfs4_layoutcommit_data *data = calldata;
    struct pnfs_layout_segment *lseg, *tmp;
    unsigned long *bitlock = &NFS_I(data->args.inode)->flags;

    pnfs_cleanup_layoutcommit(data);
    /* Matched by references in pnfs_set_layoutcommit */
    list_for_each_entry_safe(lseg, tmp, &data->lseg_list, pls_lc_list) {
        list_del_init(&lseg->pls_lc_list);
        if (test_and_clear_bit(NFS_LSEG_LAYOUTCOMMIT,
                       &lseg->pls_flags))
            pnfs_put_lseg(lseg);
    }

    clear_bit_unlock(NFS_INO_LAYOUTCOMMITTING, bitlock);
    smp_mb__after_clear_bit();
    wake_up_bit(bitlock, NFS_INO_LAYOUTCOMMITTING);

    put_rpccred(data->cred);
    kfree(data);
}

static const struct rpc_call_ops nfs4_layoutcommit_ops = {
    .rpc_call_prepare = nfs4_layoutcommit_prepare,
    .rpc_call_done = nfs4_layoutcommit_done,
    .rpc_release = nfs4_layoutcommit_release,
};

int
nfs4_proc_layoutcommit(struct nfs4_layoutcommit_data *data, bool sync)
{
    struct rpc_message msg = {
        .rpc_proc = &nfs4_procedures[NFSPROC4_CLNT_LAYOUTCOMMIT],
        .rpc_argp = &data->args,
        .rpc_resp = &data->res,
        .rpc_cred = data->cred,
    };
    struct rpc_task_setup task_setup_data = {
        .task = &data->task,
        .rpc_client = NFS_CLIENT(data->args.inode),
        .rpc_message = &msg,
        .callback_ops = &nfs4_layoutcommit_ops,
        .callback_data = data,
        .flags = RPC_TASK_ASYNC,
    };
    struct rpc_task *task;
    int status = 0;

    dprintk("NFS: %4d initiating layoutcommit call. sync %d "
        "lbw: %llu inode %lu\n",
        data->task.tk_pid, sync,
        data->args.lastbytewritten,
        data->args.inode->i_ino);

    nfs41_init_sequence(&data->args.seq_args, &data->res.seq_res, 1);
    task = rpc_run_task(&task_setup_data);
    if (IS_ERR(task))
        return PTR_ERR(task);
    if (sync == false)
        goto out;
    status = nfs4_wait_for_completion_rpc_task(task);
    if (status != 0)
        goto out;
    status = task->tk_status;
out:
    dprintk("%s: status %d\n", __func__, status);
    rpc_put_task(task);
    return status;
}

static int
_nfs41_proc_secinfo_no_name(struct nfs_server *server, struct nfs_fh *fhandle,
            struct nfs_fsinfo *info, struct nfs4_secinfo_flavors *flavors)
{
    struct nfs41_secinfo_no_name_args args = {
        .style = SECINFO_STYLE_CURRENT_FH,
    };
    struct nfs4_secinfo_res res = {
        .flavors = flavors,
    };
    struct rpc_message msg = {
        .rpc_proc = &nfs4_procedures[NFSPROC4_CLNT_SECINFO_NO_NAME],
        .rpc_argp = &args,
        .rpc_resp = &res,
    };
    return nfs4_call_sync(server->client, server, &msg, &args.seq_args, &res.seq_res, 0);
}

static int
nfs41_proc_secinfo_no_name(struct nfs_server *server, struct nfs_fh *fhandle,
               struct nfs_fsinfo *info, struct nfs4_secinfo_flavors *flavors)
{
    struct nfs4_exception exception = { };
    int err;
    do {
        err = _nfs41_proc_secinfo_no_name(server, fhandle, info, flavors);
        switch (err) {
        case 0:
        case -NFS4ERR_WRONGSEC:
        case -NFS4ERR_NOTSUPP:
            goto out;
        default:
            err = nfs4_handle_exception(server, err, &exception);
        }
    } while (exception.retry);
out:
    return err;
}

static int
nfs41_find_root_sec(struct nfs_server *server, struct nfs_fh *fhandle,
            struct nfs_fsinfo *info)
{
    int err;
    struct page *page;
    rpc_authflavor_t flavor;
    struct nfs4_secinfo_flavors *flavors;

    page = alloc_page(GFP_KERNEL);
    if (!page) {
        err = -ENOMEM;
        goto out;
    }

    flavors = page_address(page);
    err = nfs41_proc_secinfo_no_name(server, fhandle, info, flavors);

    /*
     * Fall back on "guess and check" method if
     * the server doesn't support SECINFO_NO_NAME
     */
    if (err == -NFS4ERR_WRONGSEC || err == -NFS4ERR_NOTSUPP) {
        err = nfs4_find_root_sec(server, fhandle, info);
        goto out_freepage;
    }
    if (err)
        goto out_freepage;

    flavor = nfs_find_best_sec(flavors);
    if (err == 0)
        err = nfs4_lookup_root_sec(server, fhandle, info, flavor);

out_freepage:
    put_page(page);
    if (err == -EACCES)
        return -EPERM;
out:
    return err;
}

static int _nfs41_test_stateid(struct nfs_server *server, nfs4_stateid *stateid)
{
    int status;
    struct nfs41_test_stateid_args args = {
        .stateid = stateid,
    };
    struct nfs41_test_stateid_res res;
    struct rpc_message msg = {
        .rpc_proc = &nfs4_procedures[NFSPROC4_CLNT_TEST_STATEID],
        .rpc_argp = &args,
        .rpc_resp = &res,
    };

    dprintk("NFS call  test_stateid %p\n", stateid);
    nfs41_init_sequence(&args.seq_args, &res.seq_res, 0);
    status = nfs4_call_sync_sequence(server->client, server, &msg, &args.seq_args, &res.seq_res, 1);
    if (status != NFS_OK) {
        dprintk("NFS reply test_stateid: failed, %d\n", status);
        return status;
    }
    dprintk("NFS reply test_stateid: succeeded, %d\n", -res.status);
    return -res.status;
}

static int nfs41_test_stateid(struct nfs_server *server, nfs4_stateid *stateid)
{
    struct nfs4_exception exception = { };
    int err;
    do {
        err = _nfs41_test_stateid(server, stateid);
        if (err != -NFS4ERR_DELAY)
            break;
        nfs4_handle_exception(server, err, &exception);
    } while (exception.retry);
    return err;
}

static int _nfs4_free_stateid(struct nfs_server *server, nfs4_stateid *stateid)
{
    struct nfs41_free_stateid_args args = {
        .stateid = stateid,
    };
    struct nfs41_free_stateid_res res;
    struct rpc_message msg = {
        .rpc_proc = &nfs4_procedures[NFSPROC4_CLNT_FREE_STATEID],
        .rpc_argp = &args,
        .rpc_resp = &res,
    };
    int status;

    dprintk("NFS call  free_stateid %p\n", stateid);
    nfs41_init_sequence(&args.seq_args, &res.seq_res, 0);
    status = nfs4_call_sync_sequence(server->client, server, &msg,
                     &args.seq_args, &res.seq_res, 1);
    dprintk("NFS reply free_stateid: %d\n", status);
    return status;
}

static int nfs41_free_stateid(struct nfs_server *server, nfs4_stateid *stateid)
{
    struct nfs4_exception exception = { };
    int err;
    do {
        err = _nfs4_free_stateid(server, stateid);
        if (err != -NFS4ERR_DELAY)
            break;
        nfs4_handle_exception(server, err, &exception);
    } while (exception.retry);
    return err;
}

static bool nfs41_match_stateid(const nfs4_stateid *s1,
        const nfs4_stateid *s2)
{
    if (memcmp(s1->other, s2->other, sizeof(s1->other)) != 0)
        return false;

    if (s1->seqid == s2->seqid)
        return true;
    if (s1->seqid == 0 || s2->seqid == 0)
        return true;

    return false;
}

#endif /* CONFIG_NFS_V4_1 */

static bool nfs4_match_stateid(const nfs4_stateid *s1,
        const nfs4_stateid *s2)
{
    return nfs4_stateid_match(s1, s2);
}


static const struct nfs4_state_recovery_ops nfs40_reboot_recovery_ops = {
    .owner_flag_bit = NFS_OWNER_RECLAIM_REBOOT,
    .state_flag_bit = NFS_STATE_RECLAIM_REBOOT,
    .recover_open   = nfs4_open_reclaim,
    .recover_lock   = nfs4_lock_reclaim,
    .establish_clid = nfs4_init_clientid,
    .get_clid_cred  = nfs4_get_setclientid_cred,
    .detect_trunking = nfs40_discover_server_trunking,
};

#if defined(CONFIG_NFS_V4_1)
static const struct nfs4_state_recovery_ops nfs41_reboot_recovery_ops = {
    .owner_flag_bit = NFS_OWNER_RECLAIM_REBOOT,
    .state_flag_bit = NFS_STATE_RECLAIM_REBOOT,
    .recover_open   = nfs4_open_reclaim,
    .recover_lock   = nfs4_lock_reclaim,
    .establish_clid = nfs41_init_clientid,
    .get_clid_cred  = nfs4_get_exchange_id_cred,
    .reclaim_complete = nfs41_proc_reclaim_complete,
    .detect_trunking = nfs41_discover_server_trunking,
};
#endif /* CONFIG_NFS_V4_1 */

static const struct nfs4_state_recovery_ops nfs40_nograce_recovery_ops = {
    .owner_flag_bit = NFS_OWNER_RECLAIM_NOGRACE,
    .state_flag_bit = NFS_STATE_RECLAIM_NOGRACE,
    .recover_open   = nfs4_open_expired,
    .recover_lock   = nfs4_lock_expired,
    .establish_clid = nfs4_init_clientid,
    .get_clid_cred  = nfs4_get_setclientid_cred,
};

#if defined(CONFIG_NFS_V4_1)
static const struct nfs4_state_recovery_ops nfs41_nograce_recovery_ops = {
    .owner_flag_bit = NFS_OWNER_RECLAIM_NOGRACE,
    .state_flag_bit = NFS_STATE_RECLAIM_NOGRACE,
    .recover_open   = nfs41_open_expired,
    .recover_lock   = nfs41_lock_expired,
    .establish_clid = nfs41_init_clientid,
    .get_clid_cred  = nfs4_get_exchange_id_cred,
};
#endif /* CONFIG_NFS_V4_1 */

static const struct nfs4_state_maintenance_ops nfs40_state_renewal_ops = {
    .sched_state_renewal = nfs4_proc_async_renew,
    .get_state_renewal_cred_locked = nfs4_get_renew_cred_locked,
    .renew_lease = nfs4_proc_renew,
};

#if defined(CONFIG_NFS_V4_1)
static const struct nfs4_state_maintenance_ops nfs41_state_renewal_ops = {
    .sched_state_renewal = nfs41_proc_async_sequence,
    .get_state_renewal_cred_locked = nfs4_get_machine_cred_locked,
    .renew_lease = nfs4_proc_sequence,
};
#endif

static const struct nfs4_minor_version_ops nfs_v4_0_minor_ops = {
    .minor_version = 0,
    .call_sync = _nfs4_call_sync,
    .match_stateid = nfs4_match_stateid,
    .find_root_sec = nfs4_find_root_sec,
    .reboot_recovery_ops = &nfs40_reboot_recovery_ops,
    .nograce_recovery_ops = &nfs40_nograce_recovery_ops,
    .state_renewal_ops = &nfs40_state_renewal_ops,
};

#if defined(CONFIG_NFS_V4_1)
static const struct nfs4_minor_version_ops nfs_v4_1_minor_ops = {
    .minor_version = 1,
    .call_sync = _nfs4_call_sync_session,
    .match_stateid = nfs41_match_stateid,
    .find_root_sec = nfs41_find_root_sec,
    .reboot_recovery_ops = &nfs41_reboot_recovery_ops,
    .nograce_recovery_ops = &nfs41_nograce_recovery_ops,
    .state_renewal_ops = &nfs41_state_renewal_ops,
};
#endif

const struct nfs4_minor_version_ops *nfs_v4_minor_ops[] = {
    [0] = &nfs_v4_0_minor_ops,
#if defined(CONFIG_NFS_V4_1)
    [1] = &nfs_v4_1_minor_ops,
#endif
};

const struct inode_operations nfs4_dir_inode_operations = {
    .create     = nfs_create,
    .lookup     = nfs_lookup,
    .atomic_open    = nfs_atomic_open,
    .link       = nfs_link,
    .unlink     = nfs_unlink,
    .symlink    = nfs_symlink,
    .mkdir      = nfs_mkdir,
    .rmdir      = nfs_rmdir,
    .mknod      = nfs_mknod,
    .rename     = nfs_rename,
    .permission = nfs_permission,
    .getattr    = nfs_getattr,
    .setattr    = nfs_setattr,
    .getxattr   = generic_getxattr,
    .setxattr   = generic_setxattr,
    .listxattr  = generic_listxattr,
    .removexattr    = generic_removexattr,
};

static const struct inode_operations nfs4_file_inode_operations = {
    .permission = nfs_permission,
    .getattr    = nfs_getattr,
    .setattr    = nfs_setattr,
    .getxattr   = generic_getxattr,
    .setxattr   = generic_setxattr,
    .listxattr  = generic_listxattr,
    .removexattr    = generic_removexattr,
};

const struct nfs_rpc_ops nfs_v4_clientops = {
    .version    = 4,            /* protocol version */
    .dentry_ops = &nfs4_dentry_operations,
    .dir_inode_ops  = &nfs4_dir_inode_operations,
    .file_inode_ops = &nfs4_file_inode_operations,
    .file_ops   = &nfs4_file_operations,
    .getroot    = nfs4_proc_get_root,
    .submount   = nfs4_submount,
    .try_mount  = nfs4_try_mount,
    .getattr    = nfs4_proc_getattr,
    .setattr    = nfs4_proc_setattr,
    .lookup     = nfs4_proc_lookup,
    .access     = nfs4_proc_access,
    .readlink   = nfs4_proc_readlink,
    .create     = nfs4_proc_create,
    .remove     = nfs4_proc_remove,
    .unlink_setup   = nfs4_proc_unlink_setup,
    .unlink_rpc_prepare = nfs4_proc_unlink_rpc_prepare,
    .unlink_done    = nfs4_proc_unlink_done,
    .rename     = nfs4_proc_rename,
    .rename_setup   = nfs4_proc_rename_setup,
    .rename_rpc_prepare = nfs4_proc_rename_rpc_prepare,
    .rename_done    = nfs4_proc_rename_done,
    .link       = nfs4_proc_link,
    .symlink    = nfs4_proc_symlink,
    .mkdir      = nfs4_proc_mkdir,
    .rmdir      = nfs4_proc_remove,
    .readdir    = nfs4_proc_readdir,
    .mknod      = nfs4_proc_mknod,
    .statfs     = nfs4_proc_statfs,
    .fsinfo     = nfs4_proc_fsinfo,
    .pathconf   = nfs4_proc_pathconf,
    .set_capabilities = nfs4_server_capabilities,
    .decode_dirent  = nfs4_decode_dirent,
    .read_setup = nfs4_proc_read_setup,
    .read_pageio_init = pnfs_pageio_init_read,
    .read_rpc_prepare = nfs4_proc_read_rpc_prepare,
    .read_done  = nfs4_read_done,
    .write_setup    = nfs4_proc_write_setup,
    .write_pageio_init = pnfs_pageio_init_write,
    .write_rpc_prepare = nfs4_proc_write_rpc_prepare,
    .write_done = nfs4_write_done,
    .commit_setup   = nfs4_proc_commit_setup,
    .commit_rpc_prepare = nfs4_proc_commit_rpc_prepare,
    .commit_done    = nfs4_commit_done,
    .lock       = nfs4_proc_lock,
    .clear_acl_cache = nfs4_zap_acl_attr,
    .close_context  = nfs4_close_context,
    .open_context   = nfs4_atomic_open,
    .have_delegation = nfs4_have_delegation,
    .return_delegation = nfs4_inode_return_delegation,
    .alloc_client   = nfs4_alloc_client,
    .init_client    = nfs4_init_client,
    .free_client    = nfs4_free_client,
    .create_server  = nfs4_create_server,
    .clone_server   = nfs_clone_server,
};

static const struct xattr_handler nfs4_xattr_nfs4_acl_handler = {
    .prefix = XATTR_NAME_NFSV4_ACL,
    .list   = nfs4_xattr_list_nfs4_acl,
    .get    = nfs4_xattr_get_nfs4_acl,
    .set    = nfs4_xattr_set_nfs4_acl,
};

const struct xattr_handler *nfs4_xattr_handlers[] = {
    &nfs4_xattr_nfs4_acl_handler,
    NULL
};

/*
 * Local variables:
 *  c-basic-offset: 8
 * End:
 */