smb: client: don't trust DFSREF_STORAGE_SERVER bit

JIRA: https://issues.redhat.com/browse/RHEL-78152

commit 77c2e45
Author: Paulo Alcantara <pc@manguebit.com>
Date:   Wed Feb 5 13:03:33 2025 -0300

    smb: client: don't trust DFSREF_STORAGE_SERVER bit
    
    Some servers don't respect the DFSREF_STORAGE_SERVER bit, so
    unconditionally tree connect to DFS link target and then decide
    whether or not continue chasing DFS referrals for DFS interlinks.
    Otherwise the client would fail to mount such shares.
    
    Signed-off-by: Paulo Alcantara (Red Hat) <pc@manguebit.com>
    Signed-off-by: Steve French <stfrench@microsoft.com>

Signed-off-by: Paulo Alcantara <paalcant@redhat.com>

Author: pcacjr

fs/smb/client/dfs.c

@@ -150,25 +150,27 @@ static int __dfs_referral_walk(struct dfs_ref_walk *rw)
 			if (rc)
 				continue;
 
-			if (tgt.flags & DFSREF_STORAGE_SERVER) {
-				rc = cifs_mount_get_tcon(mnt_ctx);
-				if (!rc)
-					rc = cifs_is_path_remote(mnt_ctx);
+			rc = cifs_mount_get_tcon(mnt_ctx);
+			if (rc) {
+				if (tgt.server_type == DFS_TYPE_LINK &&
+				    DFS_INTERLINK(tgt.flags))
+					rc = -EREMOTE;
+			} else {
+				rc = cifs_is_path_remote(mnt_ctx);
 				if (!rc) {
 					ref_walk_set_tgt_hint(rw);
 					break;
 				}
-				if (rc != -EREMOTE)
-					continue;
 			}
-
-			rc = ref_walk_advance(rw);
-			if (!rc) {
-				rc = setup_dfs_ref(&tgt, rw);
-				if (rc)
-					break;
-				ref_walk_mark_end(rw);
-				goto again;
+			if (rc == -EREMOTE) {
+				rc = ref_walk_advance(rw);
+				if (!rc) {
+					rc = setup_dfs_ref(&tgt, rw);
+					if (rc)
+						break;
+					ref_walk_mark_end(rw);
+					goto again;
+				}
 			}
 		}
 	} while (rc && ref_walk_descend(rw));