nfs: Fix ugly referral attributes

Before traversing a referral and performing a mount, the mounted-on
directory looks strange:

dr-xr-xr-x. 2 4294967294 4294967294 0 Dec 31  1969 dir.0

nfs4_get_referral is wiping out any cached attributes with what was
returned via GETATTR(fs_locations), but the bit mask for that
operation does not request any file attributes.

Retrieve owner and timestamp information so that the memcpy in
nfs4_get_referral fills in more attributes.

Changes since v1:
- Don't request attributes that the client unconditionally replaces
- Request only MOUNTED_ON_FILEID or FILEID attribute, not both
- encode_fs_locations() doesn't use the third bitmask word

Fixes: 6b97fd3d ("NFSv4: Follow a referral")
Suggested-by: Pradeep Thomas <pradeepthomas@gmail.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Cc: stable@vger.kernel.org
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>

fs/nfs/nfs4proc.c

@@ -258,15 +258,12 @@ const u32 nfs4_fsinfo_bitmap[3] = { FATTR4_WORD0_MAXFILESIZE
 };
 
 const u32 nfs4_fs_locations_bitmap[3] = {
-	FATTR4_WORD0_TYPE
-	| FATTR4_WORD0_CHANGE
+	FATTR4_WORD0_CHANGE
 	| FATTR4_WORD0_SIZE
 	| FATTR4_WORD0_FSID
 	| FATTR4_WORD0_FILEID
 	| FATTR4_WORD0_FS_LOCATIONS,
-	FATTR4_WORD1_MODE
-	| FATTR4_WORD1_NUMLINKS
-	| FATTR4_WORD1_OWNER
+	FATTR4_WORD1_OWNER
 	| FATTR4_WORD1_OWNER_GROUP
 	| FATTR4_WORD1_RAWDEV
 	| FATTR4_WORD1_SPACE_USED
@@ -6907,9 +6904,7 @@ static int _nfs4_proc_fs_locations(struct rpc_clnt *client, struct inode *dir,
 				   struct page *page)
 {
 	struct nfs_server *server = NFS_SERVER(dir);
-	u32 bitmask[3] = {
-		[0] = FATTR4_WORD0_FSID | FATTR4_WORD0_FS_LOCATIONS,
-	};
+	u32 bitmask[3];
 	struct nfs4_fs_locations_arg args = {
 		.dir_fh = NFS_FH(dir),
 		.name = name,
@@ -6928,12 +6923,15 @@ static int _nfs4_proc_fs_locations(struct rpc_clnt *client, struct inode *dir,
 
 	dprintk("%s: start\n", __func__);
 
+	bitmask[0] = nfs4_fattr_bitmap[0] | FATTR4_WORD0_FS_LOCATIONS;
+	bitmask[1] = nfs4_fattr_bitmap[1];
+
 	/* Ask for the fileid of the absent filesystem if mounted_on_fileid
 	 * is not supported */
 	if (NFS_SERVER(dir)->attr_bitmask[1] & FATTR4_WORD1_MOUNTED_ON_FILEID)
-		bitmask[1] |= FATTR4_WORD1_MOUNTED_ON_FILEID;
+		bitmask[0] &= ~FATTR4_WORD0_FILEID;
 	else
-		bitmask[0] |= FATTR4_WORD0_FILEID;
+		bitmask[1] &= ~FATTR4_WORD1_MOUNTED_ON_FILEID;
 
 	nfs_fattr_init(&fs_locations->fattr);
 	fs_locations->server = server;