From: Dave Chinner <dchinner@xxxxxxxxxx> When a multilevel bmbt split occurs, we can be asked to allocate blocks from an AG that has no space left available. In the case of an extent just being allocated, the first bmbt block allocation sees the firstblock parameter is set and does not set a minleft parameter for the allocation. The allocation also does not set the total number of blocks required by the allocation, either. If the extent allocation used all the free space in the AG, the lack of a total allocation size results in a block being reserved for the AG freespace btree manipulations being used incorrectly. Secondly, the allocation is only allowed to be allocated in the current AG (NEAR_BNO) because the low space algorithm has not been activated. As a result of this, the second block allocation in the split fails to find sufficient space in the current AG and fails, resulting in a dirty transaction cancellation and a filesytem shutdown. There are two problems here - both pointed out by Lachlan McIlroy when we were first discussing a proposed fix for the problem (See http://oss.sgi.com/archives/xfs/2010-09/msg00438.html). Firstly, the missing args->total was causing the initial block to be allocated from the freespace reserve. Secondly that the NEAR_BNO allocation should probably be a START_BNO allocation to allow blocks to be taken from a higher numbered AG. With these changes, the allocation failure goes away, but we trigger asserts in xfs_bmapi() that try to ensure that bmbt block allocations only occur in the same AG as the extent allocated, except if the low space algorithm is active. In this case, we don't need to activate the low space algorithm - if a START_BNO allocation fails with minleft = 0, then there is no space we can allocate at all, and hence the low space algorithm is no help. Therefore the asserts need modification reflect the new state of affairs. This commit fixes the problem demonstrated by the test case in xfstests 250. Signed-off-by: Dave Chinner <dchinner@xxxxxxxxxx> --- fs/xfs/xfs_bmap.c | 8 ++------ fs/xfs/xfs_bmap_btree.c | 7 ++----- 2 files changed, 4 insertions(+), 11 deletions(-) diff --git a/fs/xfs/xfs_bmap.c b/fs/xfs/xfs_bmap.c index fa00788..50eed97 100644 --- a/fs/xfs/xfs_bmap.c +++ b/fs/xfs/xfs_bmap.c @@ -4917,13 +4917,9 @@ error0: if (cur) { if (!error) { ASSERT(*firstblock == NULLFSBLOCK || - XFS_FSB_TO_AGNO(mp, *firstblock) == + XFS_FSB_TO_AGNO(mp, *firstblock) <= XFS_FSB_TO_AGNO(mp, - cur->bc_private.b.firstblock) || - (flist->xbf_low && - XFS_FSB_TO_AGNO(mp, *firstblock) < - XFS_FSB_TO_AGNO(mp, - cur->bc_private.b.firstblock))); + cur->bc_private.b.firstblock)); *firstblock = cur->bc_private.b.firstblock; } xfs_btree_del_cursor(cur, diff --git a/fs/xfs/xfs_bmap_btree.c b/fs/xfs/xfs_bmap_btree.c index 87d3c10..b2cdbfe 100644 --- a/fs/xfs/xfs_bmap_btree.c +++ b/fs/xfs/xfs_bmap_btree.c @@ -518,10 +518,11 @@ xfs_bmbt_alloc_block( args.mp = cur->bc_mp; args.fsbno = cur->bc_private.b.firstblock; args.firstblock = args.fsbno; + args.total = 1; + args.type = XFS_ALLOCTYPE_START_BNO; if (args.fsbno == NULLFSBLOCK) { args.fsbno = be64_to_cpu(start->l); - args.type = XFS_ALLOCTYPE_START_BNO; /* * Make sure there is sufficient room left in the AG to * complete a full tree split for an extent insert. If @@ -534,10 +535,6 @@ xfs_bmbt_alloc_block( * block allocation here and corrupt the filesystem. */ args.minleft = xfs_trans_get_block_res(args.tp); - } else if (cur->bc_private.b.flist->xbf_low) { - args.type = XFS_ALLOCTYPE_START_BNO; - } else { - args.type = XFS_ALLOCTYPE_NEAR_BNO; } args.minlen = args.maxlen = args.prod = 1; -- 1.7.2.3 _______________________________________________ xfs mailing list xfs@xxxxxxxxxxx http://oss.sgi.com/mailman/listinfo/xfs
