From ade1335afef556df6538eb02e8c0dc91fbd9cc37 Mon Sep 17 00:00:00 2001 From: Dave Chinner Date: Wed, 12 Jun 2013 12:19:08 +1000 Subject: [PATCH] xfs: ensure btree root split sets blkno correctly For CRC enabled filesystems, the BMBT is rooted in an inode, so it passes through a different code path on root splits than the freespace and inode btrees. This is much less traversed by xfstests than the other trees. When testing on a 1k block size filesystem, I've been seeing ASSERT failures in generic/234 like: XFS: Assertion failed: cur->bc_btnum != XFS_BTNUM_BMAP || cur->bc_private.b.allocated == 0, file: fs/xfs/xfs_btree.c, line: 317 which are generally preceded by a lblock check failure. I noticed this in the bmbt stats: $ pminfo -f xfs.btree.block_map xfs.btree.block_map.lookup value 39135 xfs.btree.block_map.compare value 268432 xfs.btree.block_map.insrec value 15786 xfs.btree.block_map.delrec value 13884 xfs.btree.block_map.newroot value 2 xfs.btree.block_map.killroot value 0 ..... Very little coverage of root splits and merges. Indeed, on a 4k filesystem, block_map.newroot and block_map.killroot are both zero. i.e. the code is not exercised at all, and it's the only generic btree infrastructure operation that is not exercised by a default run of xfstests. Turns out that on a 1k filesystem, generic/234 accounts for one of those two root splits, and that is somewhat of a smoking gun. In fact, it's the same problem we saw in the directory/attr code where headers are memcpy()d from one block to another without updating the self describing metadata. Simple fix - when copying the header out of the root block, make sure the block number is updated correctly. Signed-off-by: Dave Chinner Reviewed-by: Ben Myers Signed-off-by: Ben Myers --- fs/xfs/xfs_btree.c | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/fs/xfs/xfs_btree.c b/fs/xfs/xfs_btree.c index 8804b8a3c310..0903960410a2 100644 --- a/fs/xfs/xfs_btree.c +++ b/fs/xfs/xfs_btree.c @@ -2544,7 +2544,17 @@ xfs_btree_new_iroot( if (error) goto error0; + /* + * we can't just memcpy() the root in for CRC enabled btree blocks. + * In that case have to also ensure the blkno remains correct + */ memcpy(cblock, block, xfs_btree_block_len(cur)); + if (cur->bc_flags & XFS_BTREE_CRC_BLOCKS) { + if (cur->bc_flags & XFS_BTREE_LONG_PTRS) + cblock->bb_u.l.bb_blkno = cpu_to_be64(cbp->b_bn); + else + cblock->bb_u.s.bb_blkno = cpu_to_be64(cbp->b_bn); + } be16_add_cpu(&block->bb_level, 1); xfs_btree_set_numrecs(block, 1);