From 309c848002052edbec650075a1eb098b17c17f35 Mon Sep 17 00:00:00 2001 From: Dave Chinner Date: Tue, 30 Nov 2010 15:16:02 +1100 Subject: [PATCH] xfs: delayed alloc blocks beyond EOF are valid after writeback There is an assumption in the parts of XFS that flushing a dirty file will make all the delayed allocation blocks disappear from an inode. That is, that after calling xfs_flush_pages() then ip->i_delayed_blks will be zero. This is an invalid assumption as we may have specualtive preallocation beyond EOF and they are recorded in ip->i_delayed_blks. A flush of the dirty pages of an inode will not change the state of these blocks beyond EOF, so a non-zero deeelalloc block count after a flush is valid. The bmap code has an invalid ASSERT() that needs to be removed, and the swapext code has a bug in that while it swaps the data forks around, it fails to swap the i_delayed_blks counter associated with the fork and hence can get the block accounting wrong. Signed-off-by: Dave Chinner Reviewed-by: Christoph Hellwig --- fs/xfs/xfs_bmap.c | 9 +++++++-- fs/xfs/xfs_dfrag.c | 13 +++++++++++++ 2 files changed, 20 insertions(+), 2 deletions(-) diff --git a/fs/xfs/xfs_bmap.c b/fs/xfs/xfs_bmap.c index 08b179fa9e8..4111cd3966c 100644 --- a/fs/xfs/xfs_bmap.c +++ b/fs/xfs/xfs_bmap.c @@ -5471,8 +5471,13 @@ xfs_getbmap( if (error) goto out_unlock_iolock; } - - ASSERT(ip->i_delayed_blks == 0); + /* + * even after flushing the inode, there can still be delalloc + * blocks on the inode beyond EOF due to speculative + * preallocation. These are not removed until the release + * function is called or the inode is inactivated. Hence we + * cannot assert here that ip->i_delayed_blks == 0. + */ } lock = xfs_ilock_map_shared(ip); diff --git a/fs/xfs/xfs_dfrag.c b/fs/xfs/xfs_dfrag.c index 3b9582c60a2..e60490bc00a 100644 --- a/fs/xfs/xfs_dfrag.c +++ b/fs/xfs/xfs_dfrag.c @@ -377,6 +377,19 @@ xfs_swap_extents( ip->i_d.di_format = tip->i_d.di_format; tip->i_d.di_format = tmp; + /* + * The extents in the source inode could still contain speculative + * preallocation beyond EOF (e.g. the file is open but not modified + * while defrag is in progress). In that case, we need to copy over the + * number of delalloc blocks the data fork in the source inode is + * tracking beyond EOF so that when the fork is truncated away when the + * temporary inode is unlinked we don't underrun the i_delayed_blks + * counter on that inode. + */ + ASSERT(tip->i_delayed_blks == 0); + tip->i_delayed_blks = ip->i_delayed_blks; + ip->i_delayed_blks = 0; + ilf_fields = XFS_ILOG_CORE; switch(ip->i_d.di_format) { -- 2.20.1