Patch "NFS: Fix another OPEN_DOWNGRADE bug" 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: Fix another OPEN_DOWNGRADE bug

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-fix-another-open_downgrade-bug.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: Trond Myklebust <[email protected]>
Date: Sat, 25 Jun 2016 19:19:28 -0400
Subject: NFS: Fix another OPEN_DOWNGRADE bug

From: Trond Myklebust <[email protected]>

commit e547f2628327fec6afd2e03b46f113f614cca05b upstream.

Olga Kornievskaia reports that the following test fails to trigger an OPEN_DOWNGRADE on the wire, and only triggers the final CLOSE.

fd0 = open(foo, RDRW) -- should be open on the wire for "both"
fd1 = open(foo, RDONLY) -- should be open on the wire for "read" close(fd0) -- should trigger an open_downgrade read(fd1)
close(fd1)

The issue is that we're missing a check for whether or not the current state transitioned from an O_RDWR state as opposed to having transitioned from a combination of O_RDONLY and O_WRONLY.

---
 fs/nfs/nfs4proc.c |    5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

@@ -2854,12 +2854,11 @@ static void nfs4_close_prepare(struct rp
 			call_close |= is_wronly;
 		else if (is_wronly)
 			calldata->arg.fmode |= FMODE_WRITE;
+		if (calldata->arg.fmode != (FMODE_READ|FMODE_WRITE))
+			call_close |= is_rdwr;
 	} else if (is_rdwr)
 		calldata->arg.fmode |= FMODE_READ|FMODE_WRITE;
 
-	if (calldata->arg.fmode == 0)
-		call_close |= is_rdwr;
-
 	if (!nfs4_valid_open_stateid(state))
 		call_close = 0;
 	spin_unlock(&state->owner->so_lock);

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

queue-4.4/nfs-fix-another-open_downgrade-bug.patch queue-4.4/make-nfs_atomic_open-call-d_drop-on-all-open_context-errors.patch