cifs_get_root shouldn't use path with tree name

When a server returns the optional flag SMB_SHARE_IS_IN_DFS in response
to a tree connect, cifs_build_path_to_root() will return a pathname
which includes the hostname. This causes problems with cifs_get_root()
which separates each component and does a lookup for each component of
the path which in this case will incorrectly include looking up the
hostname component as a path component.

We encountered a problem with dfs shares hosted by a Netapp. When
connecting to nodes pointed to by the DFS share. The tree connect for
these nodes return SMB_SHARE_IS_IN_DFS resulting failures in lookup
in cifs_get_root().

RH bz: 1373153
The patch was tested against a Netapp simulator and by a user using an
actual Netapp server.

Signed-off-by: Sachin Prabhu <sprabhu@redhat.com>
Reported-by: Pierguido Lambri <plambri@redhat.com>
Reviewed-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Steve French <smfrench@gmail.com>

1 files changed, 2 insertions, 2 deletions

diff --git a/fs/cifs/dir.c b/fs/cifs/dir.c
index 789ff1df2d8d..2c227a99f369 100644
--- a/fs/cifs/dir.c
+++ b/fs/cifs/dir.c
@@ -47,7 +47,7 @@ renew_parental_timestamps(struct dentry *direntry)
 
 char *
 cifs_build_path_to_root(struct smb_vol *vol, struct cifs_sb_info *cifs_sb,
-			struct cifs_tcon *tcon)
+			struct cifs_tcon *tcon, int add_treename)
 {
 	int pplen = vol->prepath ? strlen(vol->prepath) + 1 : 0;
 	int dfsplen;
@@ -59,7 +59,7 @@ cifs_build_path_to_root(struct smb_vol *vol, struct cifs_sb_info *cifs_sb,
 		return full_path;
 	}
 
-	if (tcon->Flags & SMB_SHARE_IS_IN_DFS)
+	if (add_treename)
 		dfsplen = strnlen(tcon->treeName, MAX_TREE_SIZE + 1);
 	else
 		dfsplen = 0;