xfs: optimize the negative xattr caching

Since the addition of file capabilities every write needs to read xattrs to
check if we have any capabilities to clear.  In Linux 3.0 Andi Kleen added
a flag to cache the fact that we do not have any attributes on an inode.
Make sure to already mark a file as not having any attributes when reading
it from disk in case it doesn't even have an attribute fork.  Based on an
earlier patch from Andi Kleen.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Alex Elder <aelder@sgi.com>

diff --git a/fs/xfs/linux-2.6/xfs_iops.c b/fs/xfs/linux-2.6/xfs_iops.c
index 6544c3236bc8dd51bff1c8d9935d1f979830553c..b9c172b3fbbec1c6b8ac2874151f0bb1aa19240d 100644 (file)
--- a/fs/xfs/linux-2.6/xfs_iops.c
+++ b/fs/xfs/linux-2.6/xfs_iops.c
@@ -1194,9 +1194,14 @@ xfs_setup_inode(
                break;
        }
 
-       /* if there is no attribute fork no ACL can exist on this inode */
-       if (!XFS_IFORK_Q(ip))
+       /*
+        * If there is no attribute fork no ACL can exist on this inode,
+        * and it can't have any file capabilities attached to it either.
+        */
+       if (!XFS_IFORK_Q(ip)) {
+               inode_has_no_xattr(inode);
                cache_no_acl(inode);
+       }
 
        xfs_iflags_clear(ip, XFS_INEW);
        barrier();