xfs: split xfs_itruncate_finish

Split the guts of xfs_itruncate_finish that loop over the existing extents
and calls xfs_bunmapi on them into a new helper, xfs_itruncate_externs.
Make xfs_attr_inactive call it directly instead of xfs_itruncate_finish,
which allows to simplify the latter a lot, by only letting it deal with
the data fork.  As a result xfs_itruncate_finish is renamed to
xfs_itruncate_data to make its use case more obvious.

Also remove the sync parameter from xfs_itruncate_data, which has been
unessecary since the introduction of the busy extent list in 2002, and
completely dead code since 2003 when the XFS_BMAPI_ASYNC parameter was
made a no-op.

I can't actually see why the xfs_attr_inactive needs to set the transaction
sync, but let's keep this patch simple and without changes in behaviour.

Also avoid passing a useless argument to xfs_isize_check, and make it
private to xfs_inode.c.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Alex Elder <aelder@sgi.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
diff --git a/fs/xfs/xfs_vnodeops.c b/fs/xfs/xfs_vnodeops.c
index 45b8ac6..11242c4 100644
--- a/fs/xfs/xfs_vnodeops.c
+++ b/fs/xfs/xfs_vnodeops.c
@@ -220,15 +220,12 @@
 		xfs_ilock(ip, XFS_ILOCK_EXCL);
 		xfs_trans_ijoin(tp, ip);
 
-		error = xfs_itruncate_finish(&tp, ip,
-					     ip->i_size,
-					     XFS_DATA_FORK,
-					     0);
-		/*
-		 * If we get an error at this point we
-		 * simply don't bother truncating the file.
-		 */
+		error = xfs_itruncate_data(&tp, ip, ip->i_size);
 		if (error) {
+			/*
+			 * If we get an error at this point we simply don't
+			 * bother truncating the file.
+			 */
 			xfs_trans_cancel(tp,
 					 (XFS_TRANS_RELEASE_LOG_RES |
 					  XFS_TRANS_ABORT));
@@ -665,16 +662,7 @@
 		xfs_ilock(ip, XFS_ILOCK_EXCL);
 		xfs_trans_ijoin(tp, ip);
 
-		/*
-		 * normally, we have to run xfs_itruncate_finish sync.
-		 * But if filesystem is wsync and we're in the inactive
-		 * path, then we know that nlink == 0, and that the
-		 * xaction that made nlink == 0 is permanently committed
-		 * since xfs_remove runs as a synchronous transaction.
-		 */
-		error = xfs_itruncate_finish(&tp, ip, 0, XFS_DATA_FORK,
-				(!(mp->m_flags & XFS_MOUNT_WSYNC) ? 1 : 0));
-
+		error = xfs_itruncate_data(&tp, ip, 0);
 		if (error) {
 			xfs_trans_cancel(tp,
 				XFS_TRANS_RELEASE_LOG_RES | XFS_TRANS_ABORT);