[PATCH v4] NFSv4: Fix dropped lock for racing OPEN and delegation return

[Benjamin Coddington <bcodding@redhat.com>]

Commmit f5ea16137a3f ("NFSv4: Retry LOCK on OLD_STATEID during delegation
return") attempted to solve this problem by using nfs4's generic async error
handling, but introduced a regression where v4.0 lock recovery would hang.
The additional complexity introduced by overloading that error handling is
not necessary for this case.  This patch expects that commit to be
reverted.

The problem as originally explained in the above commit is:

    There's a small window where a LOCK sent during a delegation return can
    race with another OPEN on client, but the open stateid has not yet been
    updated.  In this case, the client doesn't handle the OLD_STATEID error
    from the server and will lose this lock, emitting:
    "NFS: nfs4_handle_delegation_recall_error: unhandled error -10024".

Fix this by using the old_stateid refresh helpers if the server replies
with OLD_STATEID.

Suggested-by: Trond Myklebust <trondmy@hammerspace.com>
Signed-off-by: Benjamin Coddington <bcodding@redhat.com>
---
 fs/nfs/nfs4proc.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index 6bb14f6cfbc0..30c564f053fd 100644
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -7180,8 +7180,15 @@ static void nfs4_lock_done(struct rpc_task *task, void *calldata)
 		} else if (!nfs4_update_lock_stateid(lsp, &data->res.stateid))
 			goto out_restart;
 		break;
-	case -NFS4ERR_BAD_STATEID:
 	case -NFS4ERR_OLD_STATEID:
+		if (data->arg.new_lock_owner != 0) {
+			if (nfs4_refresh_open_old_stateid(&data->arg.open_stateid,
+					lsp->ls_state))
+				goto out_restart;
+		} else if (nfs4_refresh_lock_old_stateid(&data->arg.lock_stateid, lsp))
+			goto out_restart;
+		fallthrough;
+	case -NFS4ERR_BAD_STATEID:
 	case -NFS4ERR_STALE_STATEID:
 	case -NFS4ERR_EXPIRED:
 		if (data->arg.new_lock_owner != 0) {
-- 
2.40.1