From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from bombadil.infradead.org ([65.50.211.133]:40104 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751590AbdDAGl4 (ORCPT ); Sat, 1 Apr 2017 02:41:56 -0400 From: Christoph Hellwig Subject: [PATCH 20/27] xfs: don't reserve blocks for right shift transactions Date: Sat, 1 Apr 2017 08:40:19 +0200 Message-Id: <20170401064026.5783-21-hch@lst.de> In-Reply-To: <20170401064026.5783-1-hch@lst.de> References: <20170401064026.5783-1-hch@lst.de> Sender: linux-xfs-owner@vger.kernel.org List-ID: List-Id: xfs To: stable@vger.kernel.org Cc: linux-xfs@vger.kernel.org, Brian Foster , "Darrick J . Wong" From: Brian Foster commit 48af96ab92bc68fb645068b978ce36df2379e076 upstream. The block reservation for the transaction allocated in xfs_shift_file_space() is an artifact of the original collapse range support. It exists to handle the case where a collapse range occurs, the initial extent is left shifted into a location that forms a contiguous boundary with the previous extent and thus the extents are merged. This code was subsequently refactored and reused for insert range (right shift) support. If an insert range occurs under low free space conditions, the extent at the starting offset is split before the first shift transaction is allocated. If the block reservation fails, this leaves separate, but contiguous extents around in the inode. While not a fatal problem, this is unexpected and will flag a warning on subsequent insert range operations on the inode. This problem has been reproduce intermittently by generic/270 running against a ramdisk device. Since right shift does not create new extent boundaries in the inode, a block reservation for extent merge is unnecessary. Update xfs_shift_file_space() to conditionally reserve fs blocks for left shift transactions only. This avoids the warning reproduced by generic/270. Reported-by: Ross Zwisler Signed-off-by: Brian Foster Reviewed-by: Darrick J. Wong Signed-off-by: Darrick J. Wong --- fs/xfs/xfs_bmap_util.c | 20 ++++++++++---------- 1 file changed, 10 insertions(+), 10 deletions(-) diff --git a/fs/xfs/xfs_bmap_util.c b/fs/xfs/xfs_bmap_util.c index fd459b69161e..5c395e485170 100644 --- a/fs/xfs/xfs_bmap_util.c +++ b/fs/xfs/xfs_bmap_util.c @@ -1387,10 +1387,16 @@ xfs_shift_file_space( xfs_fileoff_t stop_fsb; xfs_fileoff_t next_fsb; xfs_fileoff_t shift_fsb; + uint resblks; ASSERT(direction == SHIFT_LEFT || direction == SHIFT_RIGHT); if (direction == SHIFT_LEFT) { + /* + * Reserve blocks to cover potential extent merges after left + * shift operations. + */ + resblks = XFS_DIOSTRAT_SPACE_RES(mp, 0); next_fsb = XFS_B_TO_FSB(mp, offset + len); stop_fsb = XFS_B_TO_FSB(mp, VFS_I(ip)->i_size); } else { @@ -1398,6 +1404,7 @@ xfs_shift_file_space( * If right shift, delegate the work of initialization of * next_fsb to xfs_bmap_shift_extent as it has ilock held. */ + resblks = 0; next_fsb = NULLFSBLOCK; stop_fsb = XFS_B_TO_FSB(mp, offset); } @@ -1439,21 +1446,14 @@ xfs_shift_file_space( } while (!error && !done) { - /* - * We would need to reserve permanent block for transaction. - * This will come into picture when after shifting extent into - * hole we found that adjacent extents can be merged which - * may lead to freeing of a block during record update. - */ - error = xfs_trans_alloc(mp, &M_RES(mp)->tr_write, - XFS_DIOSTRAT_SPACE_RES(mp, 0), 0, 0, &tp); + error = xfs_trans_alloc(mp, &M_RES(mp)->tr_write, resblks, 0, 0, + &tp); if (error) break; xfs_ilock(ip, XFS_ILOCK_EXCL); error = xfs_trans_reserve_quota(tp, mp, ip->i_udquot, - ip->i_gdquot, ip->i_pdquot, - XFS_DIOSTRAT_SPACE_RES(mp, 0), 0, + ip->i_gdquot, ip->i_pdquot, resblks, 0, XFS_QMOPT_RES_REGBLKS); if (error) goto out_trans_cancel; -- 2.11.0