3.19.8-ckt8 -stable review patch.  If anyone has any objections, please let me 
know.

------------------

From: NeilBrown <ne...@suse.com>

commit efcbc04e16dfa95fef76309f89710dd1d99a5453 upstream.

It is unusual to combine the open flags O_RDONLY and O_EXCL, but
it appears that libre-office does just that.

[pid  3250] stat("/home/USER/.config", {st_mode=S_IFDIR|0700, st_size=8192, 
...}) = 0
[pid  3250] 
open("/home/USER/.config/libreoffice/4-suse/user/extensions/buildid", 
O_RDONLY|O_EXCL <unfinished ...>

NFSv4 takes O_EXCL as a sign that a setattr command should be sent,
probably to reset the timestamps.

When it was an O_RDONLY open, the SETATTR command does not
identify any actual attributes to change.
If no delegation was provided to the open, the SETATTR uses the
all-zeros stateid and the request is accepted (at least by the
Linux NFS server - no harm, no foul).

If a read-delegation was provided, this is used in the SETATTR
request, and a Netapp filer will justifiably claim
NFS4ERR_BAD_STATEID, which the Linux client takes as a sign
to retry - indefinitely.

So only treat O_EXCL specially if O_CREAT was also given.

Signed-off-by: NeilBrown <ne...@suse.com>
Signed-off-by: Trond Myklebust <trond.mykleb...@primarydata.com>
Signed-off-by: Kamal Mostafa <ka...@canonical.com>
---
 fs/nfs/nfs4proc.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index 89f6827..4b10259 100644
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -2341,7 +2341,7 @@ static int _nfs4_do_open(struct inode *dir,
                goto err_free_label;
        state = ctx->state;
 
-       if ((opendata->o_arg.open_flags & O_EXCL) &&
+       if ((opendata->o_arg.open_flags & (O_CREAT|O_EXCL)) == (O_CREAT|O_EXCL) 
&&
            (opendata->o_arg.createmode != NFS4_CREATE_GUARDED)) {
                nfs4_exclusive_attrset(opendata, sattr);
 
-- 
1.9.1

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