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xfs: ensure st_blocks never goes to zero during COW writes

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COW writes remove the amount overwritten either directly for delalloc
reservations, or in earlier deferred transactions than adding the new
amount back in the bmap map transaction.  This means st_blocks on an
inode where all data is overwritten using the COW path can temporarily
show a 0 st_blocks.  This can easily be reproduced with the pending
zoned device support where all writes use this path and trips the
check in generic/615, but could also happen on a reflink file without
that.

Fix this by temporarily add the pending blocks to be mapped to
i_delayed_blks while the item is queued.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Chandan Babu R <chandanbabu@kernel.org>
This commit is contained in:
Christoph Hellwig 2024-08-27 07:03:21 +02:00 committed by Chandan Babu R
parent 866cf1dd3d
commit 90fa22da6d
2 changed files with 18 additions and 0 deletions
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1
fs/xfs/libxfs/xfs_bmap.c
View File

@ -4856,6 +4856,7 @@ xfs_bmapi_remap(
}
ip->i_nblocks += len;
ip->i_delayed_blks -= len; /* see xfs_bmap_defer_add */
xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
if (ifp->if_format == XFS_DINODE_FMT_BTREE)

17
fs/xfs/xfs_bmap_item.c
View File

@ -346,6 +346,17 @@ xfs_bmap_defer_add(
trace_xfs_bmap_defer(bi);
xfs_bmap_update_get_group(tp->t_mountp, bi);
/*
* Ensure the deferred mapping is pre-recorded in i_delayed_blks.
*
* Otherwise stat can report zero blocks for an inode that actually has
* data when the entire mapping is in the process of being overwritten
* using the out of place write path. This is undone in xfs_bmapi_remap
* after it has incremented di_nblocks for a successful operation.
*/
if (bi->bi_type == XFS_BMAP_MAP)
bi->bi_owner->i_delayed_blks += bi->bi_bmap.br_blockcount;
xfs_defer_add(tp, &bi->bi_list, &xfs_bmap_update_defer_type);
}
@ -367,6 +378,9 @@ xfs_bmap_update_cancel_item(
{
struct xfs_bmap_intent *bi = bi_entry(item);
if (bi->bi_type == XFS_BMAP_MAP)
bi->bi_owner->i_delayed_blks -= bi->bi_bmap.br_blockcount;
xfs_bmap_update_put_group(bi);
kmem_cache_free(xfs_bmap_intent_cache, bi);
}
@ -464,6 +478,9 @@ xfs_bui_recover_work(
bi->bi_owner = *ipp;
xfs_bmap_update_get_group(mp, bi);
/* see xfs_bmap_defer_add for details */
if (bi->bi_type == XFS_BMAP_MAP)
bi->bi_owner->i_delayed_blks += bi->bi_bmap.br_blockcount;
xfs_defer_add_item(dfp, &bi->bi_list);
return bi;
}