From d4608632ec8f4ae3ffecdd343ede34e60eabc64f Mon Sep 17 00:00:00 2001 From: Eric Sandeen Date: Thu, 10 Jan 2013 10:41:48 -0600 Subject: [PATCH] xfs: recalculate leaf entry pointer after compacting a dir2 block Dave Jones hit this assert when doing a compile on recent git, with CONFIG_XFS_DEBUG enabled: XFS: Assertion failed: (char *)dup - (char *)hdr == be16_to_cpu(*xfs_dir2_data_unused_tag_p(dup)), file: fs/xfs/xfs_dir2_data.c, line: 828 Upon further digging, the tag found by xfs_dir2_data_unused_tag_p(dup) contained "2" and not the proper offset, and I found that this value was changed after the memmoves under "Use a stale leaf for our new entry." in xfs_dir2_block_addname(), i.e. memmove(&blp[mid + 1], &blp[mid], (highstale - mid) * sizeof(*blp)); overwrote it. What has happened is that the previous call to xfs_dir2_block_compact() has rearranged things; it changes btp->count as well as the blp array. So after we make that call, we must recalculate the proper pointer to the leaf entries by making another call to xfs_dir2_block_leaf_p(). Dave provided a metadump image which led to a simple reproducer (create a particular filename in the affected directory) and this resolves the testcase as well as the bug on his live system. Thanks also to dchinner for looking at this one with me. Signed-off-by: Eric Sandeen Tested-by: Dave Jones Reviewed-by: Dave Chinner Reviewed-by: Mark Tinguely Signed-off-by: Ben Myers --- fs/xfs/xfs_dir2_block.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/fs/xfs/xfs_dir2_block.c b/fs/xfs/xfs_dir2_block.c index 7536faaa61e7..12afe07a91d7 100644 --- a/fs/xfs/xfs_dir2_block.c +++ b/fs/xfs/xfs_dir2_block.c @@ -355,10 +355,12 @@ xfs_dir2_block_addname( /* * If need to compact the leaf entries, do it now. */ - if (compact) + if (compact) { xfs_dir2_block_compact(tp, bp, hdr, btp, blp, &needlog, &lfloghigh, &lfloglow); - else if (btp->stale) { + /* recalculate blp post-compaction */ + blp = xfs_dir2_block_leaf_p(btp); + } else if (btp->stale) { /* * Set leaf logging boundaries to impossible state. * For the no-stale case they're set explicitly. -- 2.20.1