delegation.c

Go to the documentation of this file.

/*
 * linux/fs/nfs/delegation.c
 *
 * Copyright (C) 2004 Trond Myklebust
 *
 * NFS file delegation management
 *
 */
#include <linux/completion.h>
#include <linux/kthread.h>
#include <linux/module.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/spinlock.h>

#include <linux/nfs4.h>
#include <linux/nfs_fs.h>
#include <linux/nfs_xdr.h>

#include "nfs4_fs.h"
#include "delegation.h"
#include "internal.h"

static void nfs_free_delegation(struct nfs_delegation *delegation)
{
    if (delegation->cred) {
        put_rpccred(delegation->cred);
        delegation->cred = NULL;
    }
    kfree_rcu(delegation, rcu);
}

void nfs_mark_delegation_referenced(struct nfs_delegation *delegation)
{
    set_bit(NFS_DELEGATION_REFERENCED, &delegation->flags);
}

int nfs4_have_delegation(struct inode *inode, fmode_t flags)
{
    struct nfs_delegation *delegation;
    int ret = 0;

    flags &= FMODE_READ|FMODE_WRITE;
    rcu_read_lock();
    delegation = rcu_dereference(NFS_I(inode)->delegation);
    if (delegation != NULL && (delegation->type & flags) == flags) {
        nfs_mark_delegation_referenced(delegation);
        ret = 1;
    }
    rcu_read_unlock();
    return ret;
}

static int nfs_delegation_claim_locks(struct nfs_open_context *ctx, struct nfs4_state *state)
{
    struct inode *inode = state->inode;
    struct file_lock *fl;
    int status = 0;

    if (inode->i_flock == NULL)
        goto out;

    /* Protect inode->i_flock using the file locks lock */
    lock_flocks();
    for (fl = inode->i_flock; fl != NULL; fl = fl->fl_next) {
        if (!(fl->fl_flags & (FL_POSIX|FL_FLOCK)))
            continue;
        if (nfs_file_open_context(fl->fl_file) != ctx)
            continue;
        unlock_flocks();
        status = nfs4_lock_delegation_recall(state, fl);
        if (status < 0)
            goto out;
        lock_flocks();
    }
    unlock_flocks();
out:
    return status;
}

static int nfs_delegation_claim_opens(struct inode *inode, const nfs4_stateid *stateid)
{
    struct nfs_inode *nfsi = NFS_I(inode);
    struct nfs_open_context *ctx;
    struct nfs4_state *state;
    int err;

again:
    spin_lock(&inode->i_lock);
    list_for_each_entry(ctx, &nfsi->open_files, list) {
        state = ctx->state;
        if (state == NULL)
            continue;
        if (!test_bit(NFS_DELEGATED_STATE, &state->flags))
            continue;
        if (!nfs4_stateid_match(&state->stateid, stateid))
            continue;
        get_nfs_open_context(ctx);
        spin_unlock(&inode->i_lock);
        err = nfs4_open_delegation_recall(ctx, state, stateid);
        if (err >= 0)
            err = nfs_delegation_claim_locks(ctx, state);
        put_nfs_open_context(ctx);
        if (err != 0)
            return err;
        goto again;
    }
    spin_unlock(&inode->i_lock);
    return 0;
}

void nfs_inode_reclaim_delegation(struct inode *inode, struct rpc_cred *cred,
                  struct nfs_openres *res)
{
    struct nfs_delegation *delegation;
    struct rpc_cred *oldcred = NULL;

    rcu_read_lock();
    delegation = rcu_dereference(NFS_I(inode)->delegation);
    if (delegation != NULL) {
        spin_lock(&delegation->lock);
        if (delegation->inode != NULL) {
            nfs4_stateid_copy(&delegation->stateid, &res->delegation);
            delegation->type = res->delegation_type;
            delegation->maxsize = res->maxsize;
            oldcred = delegation->cred;
            delegation->cred = get_rpccred(cred);
            clear_bit(NFS_DELEGATION_NEED_RECLAIM,
                  &delegation->flags);
            NFS_I(inode)->delegation_state = delegation->type;
            spin_unlock(&delegation->lock);
            put_rpccred(oldcred);
            rcu_read_unlock();
        } else {
            /* We appear to have raced with a delegation return. */
            spin_unlock(&delegation->lock);
            rcu_read_unlock();
            nfs_inode_set_delegation(inode, cred, res);
        }
    } else {
        rcu_read_unlock();
    }
}

static int nfs_do_return_delegation(struct inode *inode, struct nfs_delegation *delegation, int issync)
{
    int res = 0;

    res = nfs4_proc_delegreturn(inode, delegation->cred, &delegation->stateid, issync);
    nfs_free_delegation(delegation);
    return res;
}

static struct inode *nfs_delegation_grab_inode(struct nfs_delegation *delegation)
{
    struct inode *inode = NULL;

    spin_lock(&delegation->lock);
    if (delegation->inode != NULL)
        inode = igrab(delegation->inode);
    spin_unlock(&delegation->lock);
    return inode;
}

static struct nfs_delegation *
nfs_detach_delegation_locked(struct nfs_inode *nfsi,
                 struct nfs_server *server)
{
    struct nfs_delegation *delegation =
        rcu_dereference_protected(nfsi->delegation,
                lockdep_is_held(&server->nfs_client->cl_lock));

    if (delegation == NULL)
        goto nomatch;

    spin_lock(&delegation->lock);
    list_del_rcu(&delegation->super_list);
    delegation->inode = NULL;
    nfsi->delegation_state = 0;
    rcu_assign_pointer(nfsi->delegation, NULL);
    spin_unlock(&delegation->lock);
    return delegation;
nomatch:
    return NULL;
}

static struct nfs_delegation *nfs_detach_delegation(struct nfs_inode *nfsi,
                            struct nfs_server *server)
{
    struct nfs_client *clp = server->nfs_client;
    struct nfs_delegation *delegation;

    spin_lock(&clp->cl_lock);
    delegation = nfs_detach_delegation_locked(nfsi, server);
    spin_unlock(&clp->cl_lock);
    return delegation;
}

int nfs_inode_set_delegation(struct inode *inode, struct rpc_cred *cred, struct nfs_openres *res)
{
    struct nfs_server *server = NFS_SERVER(inode);
    struct nfs_client *clp = server->nfs_client;
    struct nfs_inode *nfsi = NFS_I(inode);
    struct nfs_delegation *delegation, *old_delegation;
    struct nfs_delegation *freeme = NULL;
    int status = 0;

    delegation = kmalloc(sizeof(*delegation), GFP_NOFS);
    if (delegation == NULL)
        return -ENOMEM;
    nfs4_stateid_copy(&delegation->stateid, &res->delegation);
    delegation->type = res->delegation_type;
    delegation->maxsize = res->maxsize;
    delegation->change_attr = inode->i_version;
    delegation->cred = get_rpccred(cred);
    delegation->inode = inode;
    delegation->flags = 1<<NFS_DELEGATION_REFERENCED;
    spin_lock_init(&delegation->lock);

    spin_lock(&clp->cl_lock);
    old_delegation = rcu_dereference_protected(nfsi->delegation,
                    lockdep_is_held(&clp->cl_lock));
    if (old_delegation != NULL) {
        if (nfs4_stateid_match(&delegation->stateid,
                    &old_delegation->stateid) &&
                delegation->type == old_delegation->type) {
            goto out;
        }
        /*
         * Deal with broken servers that hand out two
         * delegations for the same file.
         * Allow for upgrades to a WRITE delegation, but
         * nothing else.
         */
        dfprintk(FILE, "%s: server %s handed out "
                "a duplicate delegation!\n",
                __func__, clp->cl_hostname);
        if (delegation->type == old_delegation->type ||
            !(delegation->type & FMODE_WRITE)) {
            freeme = delegation;
            delegation = NULL;
            goto out;
        }
        freeme = nfs_detach_delegation_locked(nfsi, server);
    }
    list_add_rcu(&delegation->super_list, &server->delegations);
    nfsi->delegation_state = delegation->type;
    rcu_assign_pointer(nfsi->delegation, delegation);
    delegation = NULL;

    /* Ensure we revalidate the attributes and page cache! */
    spin_lock(&inode->i_lock);
    nfsi->cache_validity |= NFS_INO_REVAL_FORCED;
    spin_unlock(&inode->i_lock);

out:
    spin_unlock(&clp->cl_lock);
    if (delegation != NULL)
        nfs_free_delegation(delegation);
    if (freeme != NULL)
        nfs_do_return_delegation(inode, freeme, 0);
    return status;
}

/*
 * Basic procedure for returning a delegation to the server
 */
static int __nfs_inode_return_delegation(struct inode *inode, struct nfs_delegation *delegation, int issync)
{
    struct nfs_inode *nfsi = NFS_I(inode);
    int err;

    /*
     * Guard against new delegated open/lock/unlock calls and against
     * state recovery
     */
    down_write(&nfsi->rwsem);
    err = nfs_delegation_claim_opens(inode, &delegation->stateid);
    up_write(&nfsi->rwsem);
    if (err)
        goto out;

    err = nfs_do_return_delegation(inode, delegation, issync);
out:
    return err;
}

int nfs_client_return_marked_delegations(struct nfs_client *clp)
{
    struct nfs_delegation *delegation;
    struct nfs_server *server;
    struct inode *inode;
    int err = 0;

restart:
    rcu_read_lock();
    list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link) {
        list_for_each_entry_rcu(delegation, &server->delegations,
                                super_list) {
            if (!test_and_clear_bit(NFS_DELEGATION_RETURN,
                            &delegation->flags))
                continue;
            inode = nfs_delegation_grab_inode(delegation);
            if (inode == NULL)
                continue;
            delegation = nfs_detach_delegation(NFS_I(inode),
                                server);
            rcu_read_unlock();

            if (delegation != NULL)
                err = __nfs_inode_return_delegation(inode,
                                delegation, 0);
            iput(inode);
            if (!err)
                goto restart;
            set_bit(NFS4CLNT_DELEGRETURN, &clp->cl_state);
            return err;
        }
    }
    rcu_read_unlock();
    return 0;
}

void nfs_inode_return_delegation_noreclaim(struct inode *inode)
{
    struct nfs_server *server = NFS_SERVER(inode);
    struct nfs_inode *nfsi = NFS_I(inode);
    struct nfs_delegation *delegation;

    if (rcu_access_pointer(nfsi->delegation) != NULL) {
        delegation = nfs_detach_delegation(nfsi, server);
        if (delegation != NULL)
            nfs_do_return_delegation(inode, delegation, 0);
    }
}

int nfs4_inode_return_delegation(struct inode *inode)
{
    struct nfs_server *server = NFS_SERVER(inode);
    struct nfs_inode *nfsi = NFS_I(inode);
    struct nfs_delegation *delegation;
    int err = 0;

    nfs_wb_all(inode);
    if (rcu_access_pointer(nfsi->delegation) != NULL) {
        delegation = nfs_detach_delegation(nfsi, server);
        if (delegation != NULL) {
            err = __nfs_inode_return_delegation(inode, delegation, 1);
        }
    }
    return err;
}

static void nfs_mark_return_delegation(struct nfs_server *server,
        struct nfs_delegation *delegation)
{
    set_bit(NFS_DELEGATION_RETURN, &delegation->flags);
    set_bit(NFS4CLNT_DELEGRETURN, &server->nfs_client->cl_state);
}

void nfs_server_return_all_delegations(struct nfs_server *server)
{
    struct nfs_client *clp = server->nfs_client;
    struct nfs_delegation *delegation;

    if (clp == NULL)
        return;

    rcu_read_lock();
    list_for_each_entry_rcu(delegation, &server->delegations, super_list) {
        spin_lock(&delegation->lock);
        set_bit(NFS_DELEGATION_RETURN, &delegation->flags);
        spin_unlock(&delegation->lock);
    }
    rcu_read_unlock();

    if (nfs_client_return_marked_delegations(clp) != 0)
        nfs4_schedule_state_manager(clp);
}

static void nfs_mark_return_all_delegation_types(struct nfs_server *server,
                         fmode_t flags)
{
    struct nfs_delegation *delegation;

    list_for_each_entry_rcu(delegation, &server->delegations, super_list) {
        if ((delegation->type == (FMODE_READ|FMODE_WRITE)) && !(flags & FMODE_WRITE))
            continue;
        if (delegation->type & flags)
            nfs_mark_return_delegation(server, delegation);
    }
}

static void nfs_client_mark_return_all_delegation_types(struct nfs_client *clp,
                            fmode_t flags)
{
    struct nfs_server *server;

    rcu_read_lock();
    list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link)
        nfs_mark_return_all_delegation_types(server, flags);
    rcu_read_unlock();
}

static void nfs_delegation_run_state_manager(struct nfs_client *clp)
{
    if (test_bit(NFS4CLNT_DELEGRETURN, &clp->cl_state))
        nfs4_schedule_state_manager(clp);
}

void nfs_remove_bad_delegation(struct inode *inode)
{
    struct nfs_delegation *delegation;

    delegation = nfs_detach_delegation(NFS_I(inode), NFS_SERVER(inode));
    if (delegation) {
        nfs_inode_find_state_and_recover(inode, &delegation->stateid);
        nfs_free_delegation(delegation);
    }
}
EXPORT_SYMBOL_GPL(nfs_remove_bad_delegation);

void nfs_expire_all_delegation_types(struct nfs_client *clp, fmode_t flags)
{
    nfs_client_mark_return_all_delegation_types(clp, flags);
    nfs_delegation_run_state_manager(clp);
}

void nfs_expire_all_delegations(struct nfs_client *clp)
{
    nfs_expire_all_delegation_types(clp, FMODE_READ|FMODE_WRITE);
}

static void nfs_mark_return_unreferenced_delegations(struct nfs_server *server)
{
    struct nfs_delegation *delegation;

    list_for_each_entry_rcu(delegation, &server->delegations, super_list) {
        if (test_and_clear_bit(NFS_DELEGATION_REFERENCED, &delegation->flags))
            continue;
        nfs_mark_return_delegation(server, delegation);
    }
}

void nfs_expire_unreferenced_delegations(struct nfs_client *clp)
{
    struct nfs_server *server;

    rcu_read_lock();
    list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link)
        nfs_mark_return_unreferenced_delegations(server);
    rcu_read_unlock();

    nfs_delegation_run_state_manager(clp);
}

int nfs_async_inode_return_delegation(struct inode *inode,
                      const nfs4_stateid *stateid)
{
    struct nfs_server *server = NFS_SERVER(inode);
    struct nfs_client *clp = server->nfs_client;
    struct nfs_delegation *delegation;

    filemap_flush(inode->i_mapping);

    rcu_read_lock();
    delegation = rcu_dereference(NFS_I(inode)->delegation);

    if (!clp->cl_mvops->match_stateid(&delegation->stateid, stateid)) {
        rcu_read_unlock();
        return -ENOENT;
    }
    nfs_mark_return_delegation(server, delegation);
    rcu_read_unlock();

    nfs_delegation_run_state_manager(clp);
    return 0;
}

static struct inode *
nfs_delegation_find_inode_server(struct nfs_server *server,
                 const struct nfs_fh *fhandle)
{
    struct nfs_delegation *delegation;
    struct inode *res = NULL;

    list_for_each_entry_rcu(delegation, &server->delegations, super_list) {
        spin_lock(&delegation->lock);
        if (delegation->inode != NULL &&
            nfs_compare_fh(fhandle, &NFS_I(delegation->inode)->fh) == 0) {
            res = igrab(delegation->inode);
        }
        spin_unlock(&delegation->lock);
        if (res != NULL)
            break;
    }
    return res;
}

struct inode *nfs_delegation_find_inode(struct nfs_client *clp,
                    const struct nfs_fh *fhandle)
{
    struct nfs_server *server;
    struct inode *res = NULL;

    rcu_read_lock();
    list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link) {
        res = nfs_delegation_find_inode_server(server, fhandle);
        if (res != NULL)
            break;
    }
    rcu_read_unlock();
    return res;
}

static void nfs_delegation_mark_reclaim_server(struct nfs_server *server)
{
    struct nfs_delegation *delegation;

    list_for_each_entry_rcu(delegation, &server->delegations, super_list)
        set_bit(NFS_DELEGATION_NEED_RECLAIM, &delegation->flags);
}

void nfs_delegation_mark_reclaim(struct nfs_client *clp)
{
    struct nfs_server *server;

    rcu_read_lock();
    list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link)
        nfs_delegation_mark_reclaim_server(server);
    rcu_read_unlock();
}

void nfs_delegation_reap_unclaimed(struct nfs_client *clp)
{
    struct nfs_delegation *delegation;
    struct nfs_server *server;
    struct inode *inode;

restart:
    rcu_read_lock();
    list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link) {
        list_for_each_entry_rcu(delegation, &server->delegations,
                                super_list) {
            if (test_bit(NFS_DELEGATION_NEED_RECLAIM,
                        &delegation->flags) == 0)
                continue;
            inode = nfs_delegation_grab_inode(delegation);
            if (inode == NULL)
                continue;
            delegation = nfs_detach_delegation(NFS_I(inode),
                                server);
            rcu_read_unlock();

            if (delegation != NULL)
                nfs_free_delegation(delegation);
            iput(inode);
            goto restart;
        }
    }
    rcu_read_unlock();
}

int nfs_delegations_present(struct nfs_client *clp)
{
    struct nfs_server *server;
    int ret = 0;

    rcu_read_lock();
    list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link)
        if (!list_empty(&server->delegations)) {
            ret = 1;
            break;
        }
    rcu_read_unlock();
    return ret;
}

bool nfs4_copy_delegation_stateid(nfs4_stateid *dst, struct inode *inode,
        fmode_t flags)
{
    struct nfs_inode *nfsi = NFS_I(inode);
    struct nfs_delegation *delegation;
    bool ret;

    flags &= FMODE_READ|FMODE_WRITE;
    rcu_read_lock();
    delegation = rcu_dereference(nfsi->delegation);
    ret = (delegation != NULL && (delegation->type & flags) == flags);
    if (ret) {
        nfs4_stateid_copy(dst, &delegation->stateid);
        nfs_mark_delegation_referenced(delegation);
    }
    rcu_read_unlock();
    return ret;
}