From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx1.redhat.com ([209.132.183.28]:54100 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752597AbdBNNDP (ORCPT ); Tue, 14 Feb 2017 08:03:15 -0500 Received: from int-mx14.intmail.prod.int.phx2.redhat.com (int-mx14.intmail.prod.int.phx2.redhat.com [10.5.11.27]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id C087FC00E0BB for ; Tue, 14 Feb 2017 13:03:10 +0000 (UTC) Received: from bfoster.bfoster (dhcp-41-20.bos.redhat.com [10.18.41.20]) by int-mx14.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id v1ED3Acn020232 for ; Tue, 14 Feb 2017 08:03:10 -0500 From: Brian Foster Subject: [PATCH 3/4] xfs: handle indlen shortage on delalloc extent merge Date: Tue, 14 Feb 2017 08:03:08 -0500 Message-Id: <1487077389-5626-4-git-send-email-bfoster@redhat.com> In-Reply-To: <1487077389-5626-1-git-send-email-bfoster@redhat.com> References: <1487077389-5626-1-git-send-email-bfoster@redhat.com> Sender: linux-xfs-owner@vger.kernel.org List-ID: List-Id: xfs To: linux-xfs@vger.kernel.org When a delalloc extent is created, it can be merged with pre-existing, contiguous, delalloc extents. When this occurs, xfs_bmap_add_extent_hole_delay() merges the extents along with the associated indirect block reservations. The expectation here is that the combined worst case indlen reservation is always less than or equal to the indlen reservation for the individual extents. This is not always the case, however, as existing extents can less than the expected indlen reservation if the extent was previously split due to a hole punch. If a new extent merges with such an extent, the total indlen requirement may be larger than the sum of the indlen reservations held by both extents. xfs_bmap_add_extent_hole_delay() assumes that the worst case indlen reservation is always available and assigns it to the merged extent without consideration for the indlen held by the pre-existing extent. As a result, the subsequent xfs_mod_fdblocks() call can attempt an unintentional allocation rather than a free (indicated by an ASSERT() failure). Further, if the allocation happens to fail in this context, the failure goes unhandled and creates a filesystem wide block accounting inconsistency. Fix xfs_bmap_add_extent_hole_delay() to function as designed. Cap the indlen reservation assigned to the merged extent to the sum of the indlen reservations held by each of the individual extents. Signed-off-by: Brian Foster --- fs/xfs/libxfs/xfs_bmap.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) diff --git a/fs/xfs/libxfs/xfs_bmap.c b/fs/xfs/libxfs/xfs_bmap.c index 1cee514..73c9546 100644 --- a/fs/xfs/libxfs/xfs_bmap.c +++ b/fs/xfs/libxfs/xfs_bmap.c @@ -2805,7 +2805,8 @@ xfs_bmap_add_extent_hole_delay( oldlen = startblockval(left.br_startblock) + startblockval(new->br_startblock) + startblockval(right.br_startblock); - newlen = xfs_bmap_worst_indlen(ip, temp); + newlen = XFS_FILBLKS_MIN(xfs_bmap_worst_indlen(ip, temp), + oldlen); xfs_bmbt_set_startblock(xfs_iext_get_ext(ifp, *idx), nullstartblock((int)newlen)); trace_xfs_bmap_post_update(ip, *idx, state, _THIS_IP_); @@ -2826,7 +2827,8 @@ xfs_bmap_add_extent_hole_delay( xfs_bmbt_set_blockcount(xfs_iext_get_ext(ifp, *idx), temp); oldlen = startblockval(left.br_startblock) + startblockval(new->br_startblock); - newlen = xfs_bmap_worst_indlen(ip, temp); + newlen = XFS_FILBLKS_MIN(xfs_bmap_worst_indlen(ip, temp), + oldlen); xfs_bmbt_set_startblock(xfs_iext_get_ext(ifp, *idx), nullstartblock((int)newlen)); trace_xfs_bmap_post_update(ip, *idx, state, _THIS_IP_); @@ -2842,7 +2844,8 @@ xfs_bmap_add_extent_hole_delay( temp = new->br_blockcount + right.br_blockcount; oldlen = startblockval(new->br_startblock) + startblockval(right.br_startblock); - newlen = xfs_bmap_worst_indlen(ip, temp); + newlen = XFS_FILBLKS_MIN(xfs_bmap_worst_indlen(ip, temp), + oldlen); xfs_bmbt_set_allf(xfs_iext_get_ext(ifp, *idx), new->br_startoff, nullstartblock((int)newlen), temp, right.br_state); -- 2.7.4