From b58fa554e9b940083a0691f7234c13240fc09377 Mon Sep 17 00:00:00 2001 From: Dave Chinner Date: Wed, 28 Aug 2013 21:22:46 +1000 Subject: [PATCH] xfs: btree block LSN escaping to disk uninitialised When testing LSN ordering code for v5 superblocks, it was discovered that the the LSN embedded in the generic btree blocks was occasionally uninitialised. These values didn't get written to disk by metadata writeback - they got written by previous transactions in log recovery. The issue is here that the when the block is first allocated and initialised, the LSN field was not initialised - it gets overwritten before IO is issued on the buffer - but the value that is logged by transactions that modify the header before it is written to disk (and initialised) contain garbage. Hence the first recovery of the buffer will stamp garbage into the LSN field, and that can cause subsequent transactions to not replay correctly. The fix is simply to initialise the bb_lsn field to zero when we initialise the block for the first time. Signed-off-by: Dave Chinner Reviewed-by: Mark Tinguely Signed-off-by: Ben Myers --- fs/xfs/xfs_btree.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/fs/xfs/xfs_btree.c b/fs/xfs/xfs_btree.c index ae106f6dae4f..7a2b4da3c0db 100644 --- a/fs/xfs/xfs_btree.c +++ b/fs/xfs/xfs_btree.c @@ -978,6 +978,7 @@ xfs_btree_init_block_int( buf->bb_u.l.bb_owner = cpu_to_be64(owner); uuid_copy(&buf->bb_u.l.bb_uuid, &mp->m_sb.sb_uuid); buf->bb_u.l.bb_pad = 0; + buf->bb_u.l.bb_lsn = 0; } } else { /* owner is a 32 bit value on short blocks */ @@ -989,6 +990,7 @@ xfs_btree_init_block_int( buf->bb_u.s.bb_blkno = cpu_to_be64(blkno); buf->bb_u.s.bb_owner = cpu_to_be32(__owner); uuid_copy(&buf->bb_u.s.bb_uuid, &mp->m_sb.sb_uuid); + buf->bb_u.s.bb_lsn = 0; } } } -- 2.39.5