Patch "pNFS: Fix race in pnfs_wait_on_layoutreturn" 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

pNFS: Fix race in pnfs_wait_on_layoutreturn

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:
pnfs-fix-race-in-pnfs_wait_on_layoutreturn.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: Fri, 18 Nov 2016 15:21:30 -0500
Subject: pNFS: Fix race in pnfs_wait_on_layoutreturn

From: Trond Myklebust <[email protected]>

commit ee284e35d8c71bf5d4d807eaff6f67a17134b359 upstream.

We must put the task to sleep while holding the inode->i_lock in order to ensure atomicity with the test for NFS_LAYOUT_RETURN.

---
 fs/nfs/pnfs.c |    8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

@@ -1185,13 +1185,11 @@ bool pnfs_wait_on_layoutreturn(struct in
 	 * i_lock */
         spin_lock(&ino->i_lock);
         lo = nfsi->layout;
-        if (lo && test_bit(NFS_LAYOUT_RETURN, &lo->plh_flags))
+        if (lo && test_bit(NFS_LAYOUT_RETURN, &lo->plh_flags)) {
+                rpc_sleep_on(&NFS_SERVER(ino)->roc_rpcwaitq, task, NULL);
                 sleep = true;
+	}
         spin_unlock(&ino->i_lock);
-
-        if (sleep)
-                rpc_sleep_on(&NFS_SERVER(ino)->roc_rpcwaitq, task, NULL);
-
         return sleep;
 }
 

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

queue-4.4/pnfs-fix-race-in-pnfs_wait_on_layoutreturn.patch queue-4.4/nfs-fix-a-performance-regression-in-readdir.patch queue-4.4/nfsv4.1-nfs4_fl_prepare_ds-must-be-careful-about-reporting-success.patch