NFSv4: Ensure delegation recall and byte range lock removal don't conflict
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>
diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index f7e05ad..d512273 100644
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -4485,7 +4485,9 @@
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 @@
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? */