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NFSv4: Ensure delegation recall and byte range lock removal don't conflict

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Add a mutex to the struct nfs4_state_owner to ensure that delegation
recall doesn't conflict with byte range lock removal.

Note that we nest the new mutex _outside_ the state manager reclaim
protection (nfsi->rwsem) in order to avoid deadlocks.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
This commit is contained in:
Trond Myklebust 2013-02-07 10:54:07 -05:00
parent 37380e4264
commit 65b62a29f7
4 changed files with 16 additions and 2 deletions
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7
fs/nfs/delegation.c
View file

@ -71,8 +71,10 @@ static int nfs_delegation_claim_locks(struct nfs_open_context *ctx, struct nfs4_
int status = 0;
if (inode->i_flock == NULL)
goto out;
return 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) {
@ -113,12 +115,15 @@ again:
get_nfs_open_context(ctx);
spin_unlock(&inode->i_lock);
sp = state->owner;
/* Block nfs4_proc_unlck */
mutex_lock(&sp->so_delegreturn_mutex);
seq = raw_seqcount_begin(&sp->so_reclaim_seqcount);
err = nfs4_open_delegation_recall(ctx, state, stateid);
if (!err)
err = nfs_delegation_claim_locks(ctx, state);
if (!err && read_seqcount_retry(&sp->so_reclaim_seqcount, seq))
err = -EAGAIN;
mutex_unlock(&sp->so_delegreturn_mutex);
put_nfs_open_context(ctx);
if (err != 0)
return err;

1
fs/nfs/nfs4_fs.h
View file

@ -93,6 +93,7 @@ struct nfs4_state_owner {
struct list_head so_states;
struct nfs_seqid_counter so_seqid;
seqcount_t so_reclaim_seqcount;
struct mutex so_delegreturn_mutex;
};
enum {

9
fs/nfs/nfs4proc.c
View file

@ -4485,7 +4485,9 @@ static struct rpc_task *nfs4_do_unlck(struct file_lock *fl,
static int nfs4_proc_unlck(struct nfs4_state *state, int cmd, struct file_lock *request)
{
struct nfs_inode *nfsi = NFS_I(state->inode);
struct inode *inode = state->inode;
struct nfs4_state_owner *sp = state->owner;
struct nfs_inode *nfsi = NFS_I(inode);
struct nfs_seqid *seqid;
struct nfs4_lock_state *lsp;
struct rpc_task *task;
@ -4495,12 +4497,17 @@ static int nfs4_proc_unlck(struct nfs4_state *state, int cmd, struct file_lock *
status = nfs4_set_lock_state(state, request);
/* Unlock _before_ we do the RPC call */
request->fl_flags |= FL_EXISTS;
/* Exclude nfs_delegation_claim_locks() */
mutex_lock(&sp->so_delegreturn_mutex);
/* Exclude nfs4_reclaim_open_stateid() - note nesting! */
down_read(&nfsi->rwsem);
if (do_vfs_lock(request->fl_file, request) == -ENOENT) {
up_read(&nfsi->rwsem);
mutex_unlock(&sp->so_delegreturn_mutex);
goto out;
}
up_read(&nfsi->rwsem);
mutex_unlock(&sp->so_delegreturn_mutex);
if (status != 0)
goto out;
/* Is this a delegated lock? */

1
fs/nfs/nfs4state.c
View file

@ -519,6 +519,7 @@ nfs4_alloc_state_owner(struct nfs_server *server,
atomic_set(&sp->so_count, 1);
INIT_LIST_HEAD(&sp->so_lru);
seqcount_init(&sp->so_reclaim_seqcount);
mutex_init(&sp->so_delegreturn_mutex);
return sp;
}