cifs: We do not drop reference to tlink in CIFSCheckMFSymlink()

When we obtain tcon from cifs_sb, we use cifs_sb_tlink() to first obtain
tlink which also grabs a reference to it. We do not drop this reference
to tlink once we are done with the call.

The patch fixes this issue by instead passing tcon as a parameter and
avoids having to obtain a reference to the tlink. A lookup for the tcon
is already made in the calling functions and this way we avoid having to
re-run the lookup. This is also consistent with the argument list for
other similar calls for M-F symlinks.

We should also return an ENOSYS when we do not find a protocol specific
function to lookup the MF Symlink data.

Signed-off-by: Sachin Prabhu <sprabhu@redhat.com>
Reviewed-by: Jeff Layton <jlayton@redhat.com>
CC: Stable <stable@kernel.org>
Signed-off-by: Steve French <smfrench@gmail.com>

1 files changed, 11 insertions, 15 deletions

diff --git a/fs/cifs/link.c b/fs/cifs/link.c
index cc023471..92aee08 100644
--- a/fs/cifs/link.c
+++ b/fs/cifs/link.c
@@ -354,34 +354,30 @@ open_query_close_cifs_symlink(const unsigned char *path, char *pbuf,
 
 
 int
-CIFSCheckMFSymlink(struct cifs_fattr *fattr,
-		   const unsigned char *path,
-		   struct cifs_sb_info *cifs_sb, unsigned int xid)
+CIFSCheckMFSymlink(unsigned int xid, struct cifs_tcon *tcon,
+		   struct cifs_sb_info *cifs_sb, struct cifs_fattr *fattr,
+		   const unsigned char *path)
 {
-	int rc = 0;
+	int rc;
 	u8 *buf = NULL;
 	unsigned int link_len = 0;
 	unsigned int bytes_read = 0;
-	struct cifs_tcon *ptcon;
 
 	if (!CIFSCouldBeMFSymlink(fattr))
 		/* it's not a symlink */
 		return 0;
 
 	buf = kmalloc(CIFS_MF_SYMLINK_FILE_SIZE, GFP_KERNEL);
-	if (!buf) {
-		rc = -ENOMEM;
-		goto out;
-	}
+	if (!buf)
+		return -ENOMEM;
 
-	ptcon = tlink_tcon(cifs_sb_tlink(cifs_sb));
-	if ((ptcon->ses) && (ptcon->ses->server->ops->query_mf_symlink))
-		rc = ptcon->ses->server->ops->query_mf_symlink(path, buf,
-						 &bytes_read, cifs_sb, xid);
+	if (tcon->ses->server->ops->query_mf_symlink)
+		rc = tcon->ses->server->ops->query_mf_symlink(path, buf,
+						&bytes_read, cifs_sb, xid);
 	else
-		goto out;
+		rc = -ENOSYS;
 
-	if (rc != 0)
+	if (rc)
 		goto out;
 
 	if (bytes_read == 0) /* not a symlink */