Patch "nfs: Don't increment lock sequence ID after NFS4ERR_MOVED" has been added to the 4.4-stable tree

This is a note to let you know that I've just added the patch titled

nfs: Don't increment lock sequence ID after NFS4ERR_MOVED

to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
nfs-don-t-increment-lock-sequence-id-after-nfs4err_moved.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Chuck Lever <[email protected]>
Date: Sun, 22 Jan 2017 14:04:29 -0500
Subject: nfs: Don't increment lock sequence ID after NFS4ERR_MOVED

From: Chuck Lever <[email protected]>

commit 059aa734824165507c65fd30a55ff000afd14983 upstream.

Xuan Qi reports that the Linux NFSv4 client failed to lock a file that was migrated. The steps he observed on the wire:

1. The client sent a LOCK request to the source server
2. The source server replied NFS4ERR_MOVED
3. The client switched to the destination server
4. The client sent the same LOCK request to the destination server with a bumped lock sequence ID
5. The destination server rejected the LOCK request with NFS4ERR_BAD_SEQID

RFC 3530 section 8.1.5 provides a list of NFS errors which do not bump a lock sequence ID.

However, RFC 3530 is now obsoleted by RFC 7530. In RFC 7530 section 9.1.7, this list has been updated by the addition of NFS4ERR_MOVED.

---
 include/linux/nfs4.h |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

@@ -266,7 +266,7 @@ enum nfsstat4 {
 
 static inline bool seqid_mutating_err(u32 err)
 {
-	/* rfc 3530 section 8.1.5: */
+	/* See RFC 7530, section 9.1.7 */
 	switch (err) {
 	case NFS4ERR_STALE_CLIENTID:
 	case NFS4ERR_STALE_STATEID:

@@ -275,6 +275,7 @@ static inline bool seqid_mutating_err(u3
 	case NFS4ERR_BADXDR:
 	case NFS4ERR_RESOURCE:
 	case NFS4ERR_NOFILEHANDLE:
+	case NFS4ERR_MOVED:
 		return false;
 	};
 	return true;

Patches currently in stable-queue which might be from [email protected] are

queue-4.4/nfs-don-t-increment-lock-sequence-id-after-nfs4err_moved.patch