nfs41: do not return ENOMEM on LAYOUTUNAVAILABLE

commit 7ff4cff637aa0bd2abbd81f53b2a6206c50afd95 upstream.

A pNFS server may return LAYOUTUNAVAILABLE error on LAYOUTGET for files
which don't have any layout. In this situation pnfs_update_layout
currently returns NULL. As this NULL is converted into ENOMEM, IO
requests fails instead of falling back to MDS.

Do not return ENOMEM on LAYOUTUNAVAILABLE and let client retry through
MDS.

Fixes 8d40b0f14846f. I will suggest to backport this fix to affected
stable branches.

Signed-off-by: Tigran Mkrtchyan <tigran.mkrtchyan@desy.de>
[trondmy: Use IS_ERR_OR_NULL()]
Fixes: 8d40b0f14846 ("NFS filelayout:call GETDEVICEINFO after...")
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/fs/nfs/filelayout/filelayout.c b/fs/nfs/filelayout/filelayout.c
index 508126eb49f9577eeec6f9e1b97abf6286cc82eb..3db2b74647483a9c756de8b6b16ef50a9fea094f 100644 (file)
--- a/fs/nfs/filelayout/filelayout.c
+++ b/fs/nfs/filelayout/filelayout.c
@@ -895,9 +895,7 @@ fl_pnfs_update_layout(struct inode *ino,
 
        lseg = pnfs_update_layout(ino, ctx, pos, count, iomode, strict_iomode,
                                  gfp_flags);
-       if (!lseg)
-               lseg = ERR_PTR(-ENOMEM);
-       if (IS_ERR(lseg))
+       if (IS_ERR_OR_NULL(lseg))
                goto out;
 
        lo = NFS_I(ino)->layout;