[34-longterm 055/196] cifs: always do is_path_accessible check in cifs_mount

[Paul Gortmaker]

From: Jeff Layton <jlayton@xxxxxxxxxx>

                   -------------------
    This is a commit scheduled for the next v2.6.34 longterm release.
    If you see a problem with using this for longterm, please comment.
                   -------------------

commit 70945643722ffeac779d2529a348f99567fa5c33 upstream.

Currently, we skip doing the is_path_accessible check in cifs_mount if
there is no prefixpath. I have a report of at least one server however
that allows a TREE_CONNECT to a share that has a DFS referral at its
root. The reporter in this case was using a UNC that had no prefixpath,
so the is_path_accessible check was not triggered and the box later hit
a BUG() because we were chasing a DFS referral on the root dentry for
the mount.

This patch fixes this by removing the check for a zero-length
prefixpath.  That should make the is_path_accessible check be done in
this situation and should allow the client to chase the DFS referral at
mount time instead.

Reported-and-Tested-by: Yogesh Sharma <ysharma@xxxxxxxxx>
Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxx>
Signed-off-by: Steve French <sfrench@xxxxxxxxxx>
Signed-off-by: Paul Gortmaker <paul.gortmaker@xxxxxxxxxxxxx>
---
 fs/cifs/connect.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
index d9566bf..f6afb59 100644
--- a/fs/cifs/connect.c
+++ b/fs/cifs/connect.c
@@ -2555,7 +2555,7 @@ try_mount_again:
 
 remote_path_check:
 	/* check if a whole path (including prepath) is not remote */
-	if (!rc && cifs_sb->prepathlen && tcon) {
+	if (!rc && tcon) {
 		/* build_path_to_root works only when we have a valid tcon */
 		full_path = cifs_build_path_to_root(cifs_sb);
 		if (full_path == NULL) {
-- 
1.7.9.3

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