linux-kernel - [PATCH 3.16 092/136] nfs: Fix ugly referral attributes

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Message-ID: <lsq.1518323471.601770727@decadent.org.uk>
Date:   Sun, 11 Feb 2018 04:31:11 +0000
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org,
        "Pradeep Thomas" <pradeepthomas@...il.com>,
        "Anna Schumaker" <Anna.Schumaker@...app.com>,
        "Chuck Lever" <chuck.lever@...cle.com>
Subject: [PATCH 3.16 092/136] nfs: Fix ugly referral attributes

3.16.54-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Chuck Lever <chuck.lever@...cle.com>

commit c05cefcc72416a37eba5a2b35f0704ed758a9145 upstream.

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: 6b97fd3da1ea ("NFSv4: Follow a referral")
Suggested-by: Pradeep Thomas <pradeepthomas@...il.com>
Signed-off-by: Chuck Lever <chuck.lever@...cle.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@...app.com>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 fs/nfs/nfs4proc.c | 18 ++++++++----------
 1 file changed, 8 insertions(+), 10 deletions(-)

--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -243,15 +243,12 @@ const u32 nfs4_fsinfo_bitmap[3] = { FATT
 };
 
 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
@@ -6015,9 +6012,7 @@ static int _nfs4_proc_fs_locations(struc
 				   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,
@@ -6036,12 +6031,15 @@ static int _nfs4_proc_fs_locations(struc
 
 	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;