NFSv4: Release the sequence id before restarting a CLOSE rpc call

If the CLOSE or OPEN_DOWNGRADE call triggers a state recovery, and has
to be resent, then we must release the seqid. Otherwise the open
recovery will wait for the close to finish, which causes a deadlock.

This is mainly a NFSv4.1 problem, although it can theoretically happen
with NFSv4.0 too, in a OPEN_DOWNGRADE situation.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

3 files changed, 11 insertions, 6 deletions

diff --git a/fs/nfs/nfs4_fs.h b/fs/nfs/nfs4_fs.h
index e8791d5a2f7..865265bdca0 100644
--- a/fs/nfs/nfs4_fs.h
+++ b/fs/nfs/nfs4_fs.h
@@ -286,6 +286,7 @@ extern struct nfs_seqid *nfs_alloc_seqid(struct nfs_seqid_counter *counter);
 extern int nfs_wait_on_sequence(struct nfs_seqid *seqid, struct rpc_task *task);
 extern void nfs_increment_open_seqid(int status, struct nfs_seqid *seqid);
 extern void nfs_increment_lock_seqid(int status, struct nfs_seqid *seqid);
+extern void nfs_release_seqid(struct nfs_seqid *seqid);
 extern void nfs_free_seqid(struct nfs_seqid *seqid);
 
 extern const nfs4_stateid zero_stateid;
diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index 019a009e73a..198d51d17c1 100644
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -1835,11 +1835,10 @@ static void nfs4_close_done(struct rpc_task *task, void *data)
                         if (calldata->arg.fmode == 0)
                                 break;
                 default:
-                        if (nfs4_async_handle_error(task, server, state) == -EAGAIN) {
-                                nfs_restart_rpc(task, server->nfs_client);
-                                return;
-                        }
+                        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);
 }
 
diff --git a/fs/nfs/nfs4state.c b/fs/nfs/nfs4state.c
index 6674b28ddb6..18e8b26878c 100644
--- a/fs/nfs/nfs4state.c
+++ b/fs/nfs/nfs4state.c
@@ -765,16 +765,21 @@ struct nfs_seqid *nfs_alloc_seqid(struct nfs_seqid_counter *counter)
         return new;
 }
 
-void nfs_free_seqid(struct nfs_seqid *seqid)
+void nfs_release_seqid(struct nfs_seqid *seqid)
 {
         if (!list_empty(&seqid->list)) {
                 struct rpc_sequence *sequence = seqid->sequence->sequence;
 
                 spin_lock(&sequence->lock);
-                list_del(&seqid->list);
+                list_del_init(&seqid->list);
                 spin_unlock(&sequence->lock);
                 rpc_wake_up(&sequence->wait);
         }
+}
+
+void nfs_free_seqid(struct nfs_seqid *seqid)
+{
+        nfs_release_seqid(seqid);
         kfree(seqid);
 }