cifs: improve checking of DFS links over STATUS_OBJECT_NAME_INVALID

Do not map STATUS_OBJECT_NAME_INVALID to -EREMOTE under non-DFS
shares, or 'nodfs' mounts or CONFIG_CIFS_DFS_UPCALL=n builds.
Otherwise, in the slow path, get a referral to figure out whether it
is an actual DFS link.

This could be simply reproduced under a non-DFS share by running the
following

  $ mount.cifs //srv/share /mnt -o ...
  $ cat /mnt/$(printf '\U110000')
  cat: '/mnt/'$'\364\220\200\200': Object is remote

Fixes: c877ce47e137 ("cifs: reduce roundtrips on create/qinfo requests")
CC: stable@vger.kernel.org # 6.2
Signed-off-by: Paulo Alcantara (SUSE) <pc@manguebit.com>
Reviewed-by: Ronnie Sahlberg <lsahlber@redhat.com>
Signed-off-by: Steve French <stfrench@microsoft.com>

1 files changed, 15 insertions, 5 deletions

diff --git a/fs/cifs/cifsproto.h b/fs/cifs/cifsproto.h
index b7a36ebd0f2f..20a2f0f3f682 100644
--- a/fs/cifs/cifsproto.h
+++ b/fs/cifs/cifsproto.h
@@ -667,11 +667,21 @@ static inline int get_dfs_path(const unsigned int xid, struct cifs_ses *ses,
 int match_target_ip(struct TCP_Server_Info *server,
 		    const char *share, size_t share_len,
 		    bool *result);
-
-int cifs_dfs_query_info_nonascii_quirk(const unsigned int xid,
-				       struct cifs_tcon *tcon,
-				       struct cifs_sb_info *cifs_sb,
-				       const char *dfs_link_path);
+int cifs_inval_name_dfs_link_error(const unsigned int xid,
+				   struct cifs_tcon *tcon,
+				   struct cifs_sb_info *cifs_sb,
+				   const char *full_path,
+				   bool *islink);
+#else
+static inline int cifs_inval_name_dfs_link_error(const unsigned int xid,
+				   struct cifs_tcon *tcon,
+				   struct cifs_sb_info *cifs_sb,
+				   const char *full_path,
+				   bool *islink)
+{
+	*islink = false;
+	return 0;
+}
 #endif
 
 static inline int cifs_create_options(struct cifs_sb_info *cifs_sb, int options)