xfs: use XFS_IFORK_Q to determine the presence of an xattr fork

Modify xfs_ifork_ptr to return a NULL pointer if the caller asks for the
attribute fork but i_forkoff is zero.  This eliminates the ambiguity
between i_forkoff and i_af.if_present, which should make it easier to
understand the lifetime of attr forks.

While we're at it, remove the if_present checks around calls to
xfs_idestroy_fork and xfs_ifork_zap_attr since they can both handle attr
forks that have already been torn down.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Dave Chinner <dchinner@redhat.com>

1 files changed, 4 insertions, 7 deletions

diff --git a/fs/xfs/xfs_attr_inactive.c b/fs/xfs/xfs_attr_inactive.c
index dbe715fe92ce..ec20ad7a9001 100644
--- a/fs/xfs/xfs_attr_inactive.c
+++ b/fs/xfs/xfs_attr_inactive.c
@@ -362,12 +362,11 @@ xfs_attr_inactive(
 
 	/*
 	 * Invalidate and truncate the attribute fork extents. Make sure the
-	 * fork actually has attributes as otherwise the invalidation has no
+	 * fork actually has xattr blocks as otherwise the invalidation has no
 	 * blocks to read and returns an error. In this case, just do the fork
 	 * removal below.
 	 */
-	if (xfs_inode_hasattr(dp) &&
-	    dp->i_af.if_format != XFS_DINODE_FMT_LOCAL) {
+	if (dp->i_af.if_nextents > 0) {
 		error = xfs_attr3_root_inactive(&trans, dp);
 		if (error)
 			goto out_cancel;
@@ -388,10 +387,8 @@ out_cancel:
 	xfs_trans_cancel(trans);
 out_destroy_fork:
 	/* kill the in-core attr fork before we drop the inode lock */
-	if (dp->i_af.if_present) {
-		xfs_idestroy_fork(&dp->i_af);
-		xfs_ifork_zap_attr(dp);
-	}
+	xfs_idestroy_fork(&dp->i_af);
+	xfs_ifork_zap_attr(dp);
 	if (lock_mode)
 		xfs_iunlock(dp, lock_mode);
 	return error;