[PATCH 3.11 007/137] fuse: ignore entry-timeout on LOOKUP_REVAL

[Luis Henriques]

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

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

From: Anand Avati <avati@xxxxxxxxxx>

commit 154210ccb3a871e631bf39fdeb7a8731d98af87b upstream.

The following test case demonstrates the bug:

  sh# mount -t glusterfs localhost:meta-test /mnt/one

  sh# mount -t glusterfs localhost:meta-test /mnt/two

  sh# echo stuff > /mnt/one/file; rm -f /mnt/two/file; echo stuff > /mnt/one/file
  bash: /mnt/one/file: Stale file handle

  sh# echo stuff > /mnt/one/file; rm -f /mnt/two/file; sleep 1; echo stuff > /mnt/one/file

On the second open() on /mnt/one, FUSE would have used the old
nodeid (file handle) trying to re-open it. Gluster is returning
-ESTALE. The ESTALE propagates back to namei.c:filename_lookup()
where lookup is re-attempted with LOOKUP_REVAL. The right
behavior now, would be for FUSE to ignore the entry-timeout and
and do the up-call revalidation. Instead FUSE is ignoring
LOOKUP_REVAL, succeeding the revalidation (because entry-timeout
has not passed), and open() is again retried on the old file
handle and finally the ESTALE is going back to the application.

Fix: if revalidation is happening with LOOKUP_REVAL, then ignore
entry-timeout and always do the up-call.

Signed-off-by: Anand Avati <avati@xxxxxxxxxx>
Reviewed-by: Niels de Vos <ndevos@xxxxxxxxxx>
Signed-off-by: Miklos Szeredi <mszeredi@xxxxxxx>
[ luis: backported to 3.11: adjusted context ]
Signed-off-by: Luis Henriques <luis.henriques@xxxxxxxxxxxxx>
---
 fs/fuse/dir.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/fs/fuse/dir.c b/fs/fuse/dir.c
index ac00468b93d5..495d446b1911 100644
--- a/fs/fuse/dir.c
+++ b/fs/fuse/dir.c
@@ -186,7 +186,8 @@ static int fuse_dentry_revalidate(struct dentry *entry, unsigned int flags)
 	inode = ACCESS_ONCE(entry->d_inode);
 	if (inode && is_bad_inode(inode))
 		return 0;
-	else if (time_before64(fuse_dentry_time(entry), get_jiffies_64())) {
+	else if (time_before64(fuse_dentry_time(entry), get_jiffies_64()) ||
+		 (flags & LOOKUP_REVAL)) {
 		int err;
 		struct fuse_entry_out outarg;
 		struct fuse_req *req;
-- 
1.9.1

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