xfs: cache negative ACLs if there is no attribute fork

Always set up a negative ACL cache entry if the inode doesn't have an
attribute fork.  That behaves much better than doing this check inside
->check_acl.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs/xfs/linux-2.6/xfs_acl.c

@@ -221,21 +221,10 @@ xfs_set_acl(struct inode *inode, int type, struct posix_acl *acl)
 int
 xfs_check_acl(struct inode *inode, int mask)
 {
-	struct xfs_inode *ip;
 	struct posix_acl *acl;
 	int error = -EAGAIN;
 
-	ip = XFS_I(inode);
-	trace_xfs_check_acl(ip);
-
-	/*
-	 * If there is no attribute fork no ACL exists on this inode and
-	 * we can skip the whole exercise.
-	 *
-	 * FIXME! Fill the cache! Locking?
-	 */
-	if (!XFS_IFORK_Q(ip))
-		return -EAGAIN;
+	trace_xfs_check_acl(XFS_I(inode));
 
 	acl = xfs_get_acl(inode, ACL_TYPE_ACCESS);
 	if (IS_ERR(acl))

fs/xfs/linux-2.6/xfs_iops.c

@@ -1194,6 +1194,10 @@ xfs_setup_inode(
 		break;
 	}
 
+	/* if there is no attribute fork no ACL can exist on this inode */
+	if (!XFS_IFORK_Q(ip))
+		cache_no_acl(inode);
+
 	xfs_iflags_clear(ip, XFS_INEW);
 	barrier();