nfs4recover.c

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/*
*  Copyright (c) 2004 The Regents of the University of Michigan.
*  Copyright (c) 2012 Jeff Layton <[email protected]>
*  All rights reserved.
*
*  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/file.h>
#include <linux/slab.h>
#include <linux/namei.h>
#include <linux/crypto.h>
#include <linux/sched.h>
#include <linux/fs.h>
#include <linux/module.h>
#include <net/net_namespace.h>
#include <linux/sunrpc/rpc_pipe_fs.h>
#include <linux/sunrpc/clnt.h>
#include <linux/nfsd/cld.h>

#include "nfsd.h"
#include "state.h"
#include "vfs.h"
#include "netns.h"

#define NFSDDBG_FACILITY                NFSDDBG_PROC

/* Declarations */
struct nfsd4_client_tracking_ops {
    int (*init)(struct net *);
    void (*exit)(struct net *);
    void (*create)(struct nfs4_client *);
    void (*remove)(struct nfs4_client *);
    int (*check)(struct nfs4_client *);
    void (*grace_done)(struct net *, time_t);
};

/* Globals */
static struct file *rec_file;
static char user_recovery_dirname[PATH_MAX] = "/var/lib/nfs/v4recovery";
static struct nfsd4_client_tracking_ops *client_tracking_ops;

static int
nfs4_save_creds(const struct cred **original_creds)
{
    struct cred *new;

    new = prepare_creds();
    if (!new)
        return -ENOMEM;

    new->fsuid = 0;
    new->fsgid = 0;
    *original_creds = override_creds(new);
    put_cred(new);
    return 0;
}

static void
nfs4_reset_creds(const struct cred *original)
{
    revert_creds(original);
}

static void
md5_to_hex(char *out, char *md5)
{
    int i;

    for (i=0; i<16; i++) {
        unsigned char c = md5[i];

        *out++ = '0' + ((c&0xf0)>>4) + (c>=0xa0)*('a'-'9'-1);
        *out++ = '0' + (c&0x0f) + ((c&0x0f)>=0x0a)*('a'-'9'-1);
    }
    *out = '\0';
}

__be32
nfs4_make_rec_clidname(char *dname, struct xdr_netobj *clname)
{
    struct xdr_netobj cksum;
    struct hash_desc desc;
    struct scatterlist sg;
    __be32 status = nfserr_jukebox;

    dprintk("NFSD: nfs4_make_rec_clidname for %.*s\n",
            clname->len, clname->data);
    desc.flags = CRYPTO_TFM_REQ_MAY_SLEEP;
    desc.tfm = crypto_alloc_hash("md5", 0, CRYPTO_ALG_ASYNC);
    if (IS_ERR(desc.tfm))
        goto out_no_tfm;
    cksum.len = crypto_hash_digestsize(desc.tfm);
    cksum.data = kmalloc(cksum.len, GFP_KERNEL);
    if (cksum.data == NULL)
        goto out;

    sg_init_one(&sg, clname->data, clname->len);

    if (crypto_hash_digest(&desc, &sg, sg.length, cksum.data))
        goto out;

    md5_to_hex(dname, cksum.data);

    status = nfs_ok;
out:
    kfree(cksum.data);
    crypto_free_hash(desc.tfm);
out_no_tfm:
    return status;
}

static void
nfsd4_create_clid_dir(struct nfs4_client *clp)
{
    const struct cred *original_cred;
    char *dname = clp->cl_recdir;
    struct dentry *dir, *dentry;
    int status;

    dprintk("NFSD: nfsd4_create_clid_dir for \"%s\"\n", dname);

    if (test_and_set_bit(NFSD4_CLIENT_STABLE, &clp->cl_flags))
        return;
    if (!rec_file)
        return;
    status = nfs4_save_creds(&original_cred);
    if (status < 0)
        return;

    status = mnt_want_write_file(rec_file);
    if (status)
        return;

    dir = rec_file->f_path.dentry;
    /* lock the parent */
    mutex_lock(&dir->d_inode->i_mutex);

    dentry = lookup_one_len(dname, dir, HEXDIR_LEN-1);
    if (IS_ERR(dentry)) {
        status = PTR_ERR(dentry);
        goto out_unlock;
    }
    if (dentry->d_inode)
        /*
         * In the 4.1 case, where we're called from
         * reclaim_complete(), records from the previous reboot
         * may still be left, so this is OK.
         *
         * In the 4.0 case, we should never get here; but we may
         * as well be forgiving and just succeed silently.
         */
        goto out_put;
    status = vfs_mkdir(dir->d_inode, dentry, S_IRWXU);
out_put:
    dput(dentry);
out_unlock:
    mutex_unlock(&dir->d_inode->i_mutex);
    if (status == 0)
        vfs_fsync(rec_file, 0);
    else
        printk(KERN_ERR "NFSD: failed to write recovery record"
                " (err %d); please check that %s exists"
                " and is writeable", status,
                user_recovery_dirname);
    mnt_drop_write_file(rec_file);
    nfs4_reset_creds(original_cred);
}

typedef int (recdir_func)(struct dentry *, struct dentry *);

struct name_list {
    char name[HEXDIR_LEN];
    struct list_head list;
};

static int
nfsd4_build_namelist(void *arg, const char *name, int namlen,
        loff_t offset, u64 ino, unsigned int d_type)
{
    struct list_head *names = arg;
    struct name_list *entry;

    if (namlen != HEXDIR_LEN - 1)
        return 0;
    entry = kmalloc(sizeof(struct name_list), GFP_KERNEL);
    if (entry == NULL)
        return -ENOMEM;
    memcpy(entry->name, name, HEXDIR_LEN - 1);
    entry->name[HEXDIR_LEN - 1] = '\0';
    list_add(&entry->list, names);
    return 0;
}

static int
nfsd4_list_rec_dir(recdir_func *f)
{
    const struct cred *original_cred;
    struct dentry *dir = rec_file->f_path.dentry;
    LIST_HEAD(names);
    int status;

    status = nfs4_save_creds(&original_cred);
    if (status < 0)
        return status;

    status = vfs_llseek(rec_file, 0, SEEK_SET);
    if (status < 0) {
        nfs4_reset_creds(original_cred);
        return status;
    }

    status = vfs_readdir(rec_file, nfsd4_build_namelist, &names);
    mutex_lock_nested(&dir->d_inode->i_mutex, I_MUTEX_PARENT);
    while (!list_empty(&names)) {
        struct name_list *entry;
        entry = list_entry(names.next, struct name_list, list);
        if (!status) {
            struct dentry *dentry;
            dentry = lookup_one_len(entry->name, dir, HEXDIR_LEN-1);
            if (IS_ERR(dentry)) {
                status = PTR_ERR(dentry);
                break;
            }
            status = f(dir, dentry);
            dput(dentry);
        }
        list_del(&entry->list);
        kfree(entry);
    }
    mutex_unlock(&dir->d_inode->i_mutex);
    nfs4_reset_creds(original_cred);
    return status;
}

static int
nfsd4_unlink_clid_dir(char *name, int namlen)
{
    struct dentry *dir, *dentry;
    int status;

    dprintk("NFSD: nfsd4_unlink_clid_dir. name %.*s\n", namlen, name);

    dir = rec_file->f_path.dentry;
    mutex_lock_nested(&dir->d_inode->i_mutex, I_MUTEX_PARENT);
    dentry = lookup_one_len(name, dir, namlen);
    if (IS_ERR(dentry)) {
        status = PTR_ERR(dentry);
        goto out_unlock;
    }
    status = -ENOENT;
    if (!dentry->d_inode)
        goto out;
    status = vfs_rmdir(dir->d_inode, dentry);
out:
    dput(dentry);
out_unlock:
    mutex_unlock(&dir->d_inode->i_mutex);
    return status;
}

static void
nfsd4_remove_clid_dir(struct nfs4_client *clp)
{
    const struct cred *original_cred;
    int status;

    if (!rec_file || !test_bit(NFSD4_CLIENT_STABLE, &clp->cl_flags))
        return;

    status = mnt_want_write_file(rec_file);
    if (status)
        goto out;
    clear_bit(NFSD4_CLIENT_STABLE, &clp->cl_flags);

    status = nfs4_save_creds(&original_cred);
    if (status < 0)
        goto out;

    status = nfsd4_unlink_clid_dir(clp->cl_recdir, HEXDIR_LEN-1);
    nfs4_reset_creds(original_cred);
    if (status == 0)
        vfs_fsync(rec_file, 0);
    mnt_drop_write_file(rec_file);
out:
    if (status)
        printk("NFSD: Failed to remove expired client state directory"
                " %.*s\n", HEXDIR_LEN, clp->cl_recdir);
}

static int
purge_old(struct dentry *parent, struct dentry *child)
{
    int status;

    if (nfs4_has_reclaimed_state(child->d_name.name, false))
        return 0;

    status = vfs_rmdir(parent->d_inode, child);
    if (status)
        printk("failed to remove client recovery directory %s\n",
                child->d_name.name);
    /* Keep trying, success or failure: */
    return 0;
}

static void
nfsd4_recdir_purge_old(struct net *net, time_t boot_time)
{
    int status;

    if (!rec_file)
        return;
    status = mnt_want_write_file(rec_file);
    if (status)
        goto out;
    status = nfsd4_list_rec_dir(purge_old);
    if (status == 0)
        vfs_fsync(rec_file, 0);
    mnt_drop_write_file(rec_file);
out:
    if (status)
        printk("nfsd4: failed to purge old clients from recovery"
            " directory %s\n", rec_file->f_path.dentry->d_name.name);
}

static int
load_recdir(struct dentry *parent, struct dentry *child)
{
    if (child->d_name.len != HEXDIR_LEN - 1) {
        printk("nfsd4: illegal name %s in recovery directory\n",
                child->d_name.name);
        /* Keep trying; maybe the others are OK: */
        return 0;
    }
    nfs4_client_to_reclaim(child->d_name.name);
    return 0;
}

static int
nfsd4_recdir_load(void) {
    int status;

    if (!rec_file)
        return 0;

    status = nfsd4_list_rec_dir(load_recdir);
    if (status)
        printk("nfsd4: failed loading clients from recovery"
            " directory %s\n", rec_file->f_path.dentry->d_name.name);
    return status;
}

/*
 * Hold reference to the recovery directory.
 */

static int
nfsd4_init_recdir(void)
{
    const struct cred *original_cred;
    int status;

    printk("NFSD: Using %s as the NFSv4 state recovery directory\n",
            user_recovery_dirname);

    BUG_ON(rec_file);

    status = nfs4_save_creds(&original_cred);
    if (status < 0) {
        printk("NFSD: Unable to change credentials to find recovery"
               " directory: error %d\n",
               status);
        return status;
    }

    rec_file = filp_open(user_recovery_dirname, O_RDONLY | O_DIRECTORY, 0);
    if (IS_ERR(rec_file)) {
        printk("NFSD: unable to find recovery directory %s\n",
                user_recovery_dirname);
        status = PTR_ERR(rec_file);
        rec_file = NULL;
    }

    nfs4_reset_creds(original_cred);
    return status;
}

static int
nfsd4_load_reboot_recovery_data(struct net *net)
{
    int status;

    /* XXX: The legacy code won't work in a container */
    if (net != &init_net) {
        WARN(1, KERN_ERR "NFSD: attempt to initialize legacy client "
            "tracking in a container!\n");
        return -EINVAL;
    }

    nfs4_lock_state();
    status = nfsd4_init_recdir();
    if (!status)
        status = nfsd4_recdir_load();
    nfs4_unlock_state();
    if (status)
        printk(KERN_ERR "NFSD: Failure reading reboot recovery data\n");
    return status;
}

static void
nfsd4_shutdown_recdir(void)
{
    if (!rec_file)
        return;
    fput(rec_file);
    rec_file = NULL;
}

static void
nfsd4_legacy_tracking_exit(struct net *net)
{
    nfs4_release_reclaim();
    nfsd4_shutdown_recdir();
}

/*
 * Change the NFSv4 recovery directory to recdir.
 */
int
nfs4_reset_recoverydir(char *recdir)
{
    int status;
    struct path path;

    status = kern_path(recdir, LOOKUP_FOLLOW, &path);
    if (status)
        return status;
    status = -ENOTDIR;
    if (S_ISDIR(path.dentry->d_inode->i_mode)) {
        strcpy(user_recovery_dirname, recdir);
        status = 0;
    }
    path_put(&path);
    return status;
}

char *
nfs4_recoverydir(void)
{
    return user_recovery_dirname;
}

static int
nfsd4_check_legacy_client(struct nfs4_client *clp)
{
    /* did we already find that this client is stable? */
    if (test_bit(NFSD4_CLIENT_STABLE, &clp->cl_flags))
        return 0;

    /* look for it in the reclaim hashtable otherwise */
    if (nfsd4_find_reclaim_client(clp)) {
        set_bit(NFSD4_CLIENT_STABLE, &clp->cl_flags);
        return 0;
    }

    return -ENOENT;
}

static struct nfsd4_client_tracking_ops nfsd4_legacy_tracking_ops = {
    .init       = nfsd4_load_reboot_recovery_data,
    .exit       = nfsd4_legacy_tracking_exit,
    .create     = nfsd4_create_clid_dir,
    .remove     = nfsd4_remove_clid_dir,
    .check      = nfsd4_check_legacy_client,
    .grace_done = nfsd4_recdir_purge_old,
};

/* Globals */
#define NFSD_PIPE_DIR       "nfsd"
#define NFSD_CLD_PIPE       "cld"

/* per-net-ns structure for holding cld upcall info */
struct cld_net {
    struct rpc_pipe     *cn_pipe;
    spinlock_t       cn_lock;
    struct list_head     cn_list;
    unsigned int         cn_xid;
};

struct cld_upcall {
    struct list_head     cu_list;
    struct cld_net      *cu_net;
    struct task_struct  *cu_task;
    struct cld_msg       cu_msg;
};

static int
__cld_pipe_upcall(struct rpc_pipe *pipe, struct cld_msg *cmsg)
{
    int ret;
    struct rpc_pipe_msg msg;

    memset(&msg, 0, sizeof(msg));
    msg.data = cmsg;
    msg.len = sizeof(*cmsg);

    /*
     * Set task state before we queue the upcall. That prevents
     * wake_up_process in the downcall from racing with schedule.
     */
    set_current_state(TASK_UNINTERRUPTIBLE);
    ret = rpc_queue_upcall(pipe, &msg);
    if (ret < 0) {
        set_current_state(TASK_RUNNING);
        goto out;
    }

    schedule();
    set_current_state(TASK_RUNNING);

    if (msg.errno < 0)
        ret = msg.errno;
out:
    return ret;
}

static int
cld_pipe_upcall(struct rpc_pipe *pipe, struct cld_msg *cmsg)
{
    int ret;

    /*
     * -EAGAIN occurs when pipe is closed and reopened while there are
     *  upcalls queued.
     */
    do {
        ret = __cld_pipe_upcall(pipe, cmsg);
    } while (ret == -EAGAIN);

    return ret;
}

static ssize_t
cld_pipe_downcall(struct file *filp, const char __user *src, size_t mlen)
{
    struct cld_upcall *tmp, *cup;
    struct cld_msg __user *cmsg = (struct cld_msg __user *)src;
    uint32_t xid;
    struct nfsd_net *nn = net_generic(filp->f_dentry->d_sb->s_fs_info,
                        nfsd_net_id);
    struct cld_net *cn = nn->cld_net;

    if (mlen != sizeof(*cmsg)) {
        dprintk("%s: got %zu bytes, expected %zu\n", __func__, mlen,
            sizeof(*cmsg));
        return -EINVAL;
    }

    /* copy just the xid so we can try to find that */
    if (copy_from_user(&xid, &cmsg->cm_xid, sizeof(xid)) != 0) {
        dprintk("%s: error when copying xid from userspace", __func__);
        return -EFAULT;
    }

    /* walk the list and find corresponding xid */
    cup = NULL;
    spin_lock(&cn->cn_lock);
    list_for_each_entry(tmp, &cn->cn_list, cu_list) {
        if (get_unaligned(&tmp->cu_msg.cm_xid) == xid) {
            cup = tmp;
            list_del_init(&cup->cu_list);
            break;
        }
    }
    spin_unlock(&cn->cn_lock);

    /* couldn't find upcall? */
    if (!cup) {
        dprintk("%s: couldn't find upcall -- xid=%u\n", __func__, xid);
        return -EINVAL;
    }

    if (copy_from_user(&cup->cu_msg, src, mlen) != 0)
        return -EFAULT;

    wake_up_process(cup->cu_task);
    return mlen;
}

static void
cld_pipe_destroy_msg(struct rpc_pipe_msg *msg)
{
    struct cld_msg *cmsg = msg->data;
    struct cld_upcall *cup = container_of(cmsg, struct cld_upcall,
                         cu_msg);

    /* errno >= 0 means we got a downcall */
    if (msg->errno >= 0)
        return;

    wake_up_process(cup->cu_task);
}

static const struct rpc_pipe_ops cld_upcall_ops = {
    .upcall     = rpc_pipe_generic_upcall,
    .downcall   = cld_pipe_downcall,
    .destroy_msg    = cld_pipe_destroy_msg,
};

static struct dentry *
nfsd4_cld_register_sb(struct super_block *sb, struct rpc_pipe *pipe)
{
    struct dentry *dir, *dentry;

    dir = rpc_d_lookup_sb(sb, NFSD_PIPE_DIR);
    if (dir == NULL)
        return ERR_PTR(-ENOENT);
    dentry = rpc_mkpipe_dentry(dir, NFSD_CLD_PIPE, NULL, pipe);
    dput(dir);
    return dentry;
}

static void
nfsd4_cld_unregister_sb(struct rpc_pipe *pipe)
{
    if (pipe->dentry)
        rpc_unlink(pipe->dentry);
}

static struct dentry *
nfsd4_cld_register_net(struct net *net, struct rpc_pipe *pipe)
{
    struct super_block *sb;
    struct dentry *dentry;

    sb = rpc_get_sb_net(net);
    if (!sb)
        return NULL;
    dentry = nfsd4_cld_register_sb(sb, pipe);
    rpc_put_sb_net(net);
    return dentry;
}

static void
nfsd4_cld_unregister_net(struct net *net, struct rpc_pipe *pipe)
{
    struct super_block *sb;

    sb = rpc_get_sb_net(net);
    if (sb) {
        nfsd4_cld_unregister_sb(pipe);
        rpc_put_sb_net(net);
    }
}

/* Initialize rpc_pipefs pipe for communication with client tracking daemon */
static int
nfsd4_init_cld_pipe(struct net *net)
{
    int ret;
    struct dentry *dentry;
    struct nfsd_net *nn = net_generic(net, nfsd_net_id);
    struct cld_net *cn;

    if (nn->cld_net)
        return 0;

    cn = kzalloc(sizeof(*cn), GFP_KERNEL);
    if (!cn) {
        ret = -ENOMEM;
        goto err;
    }

    cn->cn_pipe = rpc_mkpipe_data(&cld_upcall_ops, RPC_PIPE_WAIT_FOR_OPEN);
    if (IS_ERR(cn->cn_pipe)) {
        ret = PTR_ERR(cn->cn_pipe);
        goto err;
    }
    spin_lock_init(&cn->cn_lock);
    INIT_LIST_HEAD(&cn->cn_list);

    dentry = nfsd4_cld_register_net(net, cn->cn_pipe);
    if (IS_ERR(dentry)) {
        ret = PTR_ERR(dentry);
        goto err_destroy_data;
    }

    cn->cn_pipe->dentry = dentry;
    nn->cld_net = cn;
    return 0;

err_destroy_data:
    rpc_destroy_pipe_data(cn->cn_pipe);
err:
    kfree(cn);
    printk(KERN_ERR "NFSD: unable to create nfsdcld upcall pipe (%d)\n",
            ret);
    return ret;
}

static void
nfsd4_remove_cld_pipe(struct net *net)
{
    struct nfsd_net *nn = net_generic(net, nfsd_net_id);
    struct cld_net *cn = nn->cld_net;

    nfsd4_cld_unregister_net(net, cn->cn_pipe);
    rpc_destroy_pipe_data(cn->cn_pipe);
    kfree(nn->cld_net);
    nn->cld_net = NULL;
}

static struct cld_upcall *
alloc_cld_upcall(struct cld_net *cn)
{
    struct cld_upcall *new, *tmp;

    new = kzalloc(sizeof(*new), GFP_KERNEL);
    if (!new)
        return new;

    /* FIXME: hard cap on number in flight? */
restart_search:
    spin_lock(&cn->cn_lock);
    list_for_each_entry(tmp, &cn->cn_list, cu_list) {
        if (tmp->cu_msg.cm_xid == cn->cn_xid) {
            cn->cn_xid++;
            spin_unlock(&cn->cn_lock);
            goto restart_search;
        }
    }
    new->cu_task = current;
    new->cu_msg.cm_vers = CLD_UPCALL_VERSION;
    put_unaligned(cn->cn_xid++, &new->cu_msg.cm_xid);
    new->cu_net = cn;
    list_add(&new->cu_list, &cn->cn_list);
    spin_unlock(&cn->cn_lock);

    dprintk("%s: allocated xid %u\n", __func__, new->cu_msg.cm_xid);

    return new;
}

static void
free_cld_upcall(struct cld_upcall *victim)
{
    struct cld_net *cn = victim->cu_net;

    spin_lock(&cn->cn_lock);
    list_del(&victim->cu_list);
    spin_unlock(&cn->cn_lock);
    kfree(victim);
}

/* Ask daemon to create a new record */
static void
nfsd4_cld_create(struct nfs4_client *clp)
{
    int ret;
    struct cld_upcall *cup;
    /* FIXME: determine net from clp */
    struct nfsd_net *nn = net_generic(&init_net, nfsd_net_id);
    struct cld_net *cn = nn->cld_net;

    /* Don't upcall if it's already stored */
    if (test_bit(NFSD4_CLIENT_STABLE, &clp->cl_flags))
        return;

    cup = alloc_cld_upcall(cn);
    if (!cup) {
        ret = -ENOMEM;
        goto out_err;
    }

    cup->cu_msg.cm_cmd = Cld_Create;
    cup->cu_msg.cm_u.cm_name.cn_len = clp->cl_name.len;
    memcpy(cup->cu_msg.cm_u.cm_name.cn_id, clp->cl_name.data,
            clp->cl_name.len);

    ret = cld_pipe_upcall(cn->cn_pipe, &cup->cu_msg);
    if (!ret) {
        ret = cup->cu_msg.cm_status;
        set_bit(NFSD4_CLIENT_STABLE, &clp->cl_flags);
    }

    free_cld_upcall(cup);
out_err:
    if (ret)
        printk(KERN_ERR "NFSD: Unable to create client "
                "record on stable storage: %d\n", ret);
}

/* Ask daemon to create a new record */
static void
nfsd4_cld_remove(struct nfs4_client *clp)
{
    int ret;
    struct cld_upcall *cup;
    /* FIXME: determine net from clp */
    struct nfsd_net *nn = net_generic(&init_net, nfsd_net_id);
    struct cld_net *cn = nn->cld_net;

    /* Don't upcall if it's already removed */
    if (!test_bit(NFSD4_CLIENT_STABLE, &clp->cl_flags))
        return;

    cup = alloc_cld_upcall(cn);
    if (!cup) {
        ret = -ENOMEM;
        goto out_err;
    }

    cup->cu_msg.cm_cmd = Cld_Remove;
    cup->cu_msg.cm_u.cm_name.cn_len = clp->cl_name.len;
    memcpy(cup->cu_msg.cm_u.cm_name.cn_id, clp->cl_name.data,
            clp->cl_name.len);

    ret = cld_pipe_upcall(cn->cn_pipe, &cup->cu_msg);
    if (!ret) {
        ret = cup->cu_msg.cm_status;
        clear_bit(NFSD4_CLIENT_STABLE, &clp->cl_flags);
    }

    free_cld_upcall(cup);
out_err:
    if (ret)
        printk(KERN_ERR "NFSD: Unable to remove client "
                "record from stable storage: %d\n", ret);
}

/* Check for presence of a record, and update its timestamp */
static int
nfsd4_cld_check(struct nfs4_client *clp)
{
    int ret;
    struct cld_upcall *cup;
    /* FIXME: determine net from clp */
    struct nfsd_net *nn = net_generic(&init_net, nfsd_net_id);
    struct cld_net *cn = nn->cld_net;

    /* Don't upcall if one was already stored during this grace pd */
    if (test_bit(NFSD4_CLIENT_STABLE, &clp->cl_flags))
        return 0;

    cup = alloc_cld_upcall(cn);
    if (!cup) {
        printk(KERN_ERR "NFSD: Unable to check client record on "
                "stable storage: %d\n", -ENOMEM);
        return -ENOMEM;
    }

    cup->cu_msg.cm_cmd = Cld_Check;
    cup->cu_msg.cm_u.cm_name.cn_len = clp->cl_name.len;
    memcpy(cup->cu_msg.cm_u.cm_name.cn_id, clp->cl_name.data,
            clp->cl_name.len);

    ret = cld_pipe_upcall(cn->cn_pipe, &cup->cu_msg);
    if (!ret) {
        ret = cup->cu_msg.cm_status;
        set_bit(NFSD4_CLIENT_STABLE, &clp->cl_flags);
    }

    free_cld_upcall(cup);
    return ret;
}

static void
nfsd4_cld_grace_done(struct net *net, time_t boot_time)
{
    int ret;
    struct cld_upcall *cup;
    struct nfsd_net *nn = net_generic(net, nfsd_net_id);
    struct cld_net *cn = nn->cld_net;

    cup = alloc_cld_upcall(cn);
    if (!cup) {
        ret = -ENOMEM;
        goto out_err;
    }

    cup->cu_msg.cm_cmd = Cld_GraceDone;
    cup->cu_msg.cm_u.cm_gracetime = (int64_t)boot_time;
    ret = cld_pipe_upcall(cn->cn_pipe, &cup->cu_msg);
    if (!ret)
        ret = cup->cu_msg.cm_status;

    free_cld_upcall(cup);
out_err:
    if (ret)
        printk(KERN_ERR "NFSD: Unable to end grace period: %d\n", ret);
}

static struct nfsd4_client_tracking_ops nfsd4_cld_tracking_ops = {
    .init       = nfsd4_init_cld_pipe,
    .exit       = nfsd4_remove_cld_pipe,
    .create     = nfsd4_cld_create,
    .remove     = nfsd4_cld_remove,
    .check      = nfsd4_cld_check,
    .grace_done = nfsd4_cld_grace_done,
};

int
nfsd4_client_tracking_init(struct net *net)
{
    int status;
    struct path path;

    if (!client_tracking_ops) {
        client_tracking_ops = &nfsd4_cld_tracking_ops;
        status = kern_path(nfs4_recoverydir(), LOOKUP_FOLLOW, &path);
        if (!status) {
            if (S_ISDIR(path.dentry->d_inode->i_mode))
                client_tracking_ops =
                        &nfsd4_legacy_tracking_ops;
            path_put(&path);
        }
    }

    status = client_tracking_ops->init(net);
    if (status) {
        printk(KERN_WARNING "NFSD: Unable to initialize client "
                    "recovery tracking! (%d)\n", status);
        client_tracking_ops = NULL;
    }
    return status;
}

void
nfsd4_client_tracking_exit(struct net *net)
{
    if (client_tracking_ops) {
        client_tracking_ops->exit(net);
        client_tracking_ops = NULL;
    }
}

void
nfsd4_client_record_create(struct nfs4_client *clp)
{
    if (client_tracking_ops)
        client_tracking_ops->create(clp);
}

void
nfsd4_client_record_remove(struct nfs4_client *clp)
{
    if (client_tracking_ops)
        client_tracking_ops->remove(clp);
}

int
nfsd4_client_record_check(struct nfs4_client *clp)
{
    if (client_tracking_ops)
        return client_tracking_ops->check(clp);

    return -EOPNOTSUPP;
}

void
nfsd4_record_grace_done(struct net *net, time_t boot_time)
{
    if (client_tracking_ops)
        client_tracking_ops->grace_done(net, boot_time);
}

static int
rpc_pipefs_event(struct notifier_block *nb, unsigned long event, void *ptr)
{
    struct super_block *sb = ptr;
    struct net *net = sb->s_fs_info;
    struct nfsd_net *nn = net_generic(net, nfsd_net_id);
    struct cld_net *cn = nn->cld_net;
    struct dentry *dentry;
    int ret = 0;

    if (!try_module_get(THIS_MODULE))
        return 0;

    if (!cn) {
        module_put(THIS_MODULE);
        return 0;
    }

    switch (event) {
    case RPC_PIPEFS_MOUNT:
        dentry = nfsd4_cld_register_sb(sb, cn->cn_pipe);
        if (IS_ERR(dentry)) {
            ret = PTR_ERR(dentry);
            break;
        }
        cn->cn_pipe->dentry = dentry;
        break;
    case RPC_PIPEFS_UMOUNT:
        if (cn->cn_pipe->dentry)
            nfsd4_cld_unregister_sb(cn->cn_pipe);
        break;
    default:
        ret = -ENOTSUPP;
        break;
    }
    module_put(THIS_MODULE);
    return ret;
}

static struct notifier_block nfsd4_cld_block = {
    .notifier_call = rpc_pipefs_event,
};

int
register_cld_notifier(void)
{
    return rpc_pipefs_notifier_register(&nfsd4_cld_block);
}

void
unregister_cld_notifier(void)
{
    rpc_pipefs_notifier_unregister(&nfsd4_cld_block);
}