On 9.08.2018 10:03, Qu Wenruo wrote:
> [BUG]
> In the following case, rescan won't zero out the number of qgroup 1/0:
> ------
> $ mkfs.btrfs -fq $DEV
> $ mount $DEV /mnt
>
> $ btrfs quota enable /mnt
> $ btrfs qgroup create 1/0 /mnt
> $ btrfs sub create /mnt/sub
> $ btrfs qgroup assign 0/257 1/0 /mnt
>
> $ dd if=/dev/urandom of=/mnt/sub/file bs=1k count=1000
> $ btrfs sub snap /mnt/sub /mnt/snap
> $ btrfs quota rescan -w /mnt
> $ btrfs qgroup show -pcre /mnt
> qgroupid rfer excl max_rfer max_excl parent child
> -------- ---- ---- -------- -------- ------ -----
> 0/5 16.00KiB 16.00KiB none none --- ---
> 0/257 1016.00KiB 16.00KiB none none 1/0 ---
> 0/258 1016.00KiB 16.00KiB none none --- ---
> 1/0 1016.00KiB 16.00KiB none none --- 0/257
>
> so far so good, but:
>
> $ btrfs qgroup remove 0/257 1/0 /mnt
> WARNING: quotas may be inconsistent, rescan needed
> $ btrfs quota rescan -w /mnt
> $ btrfs qgroup show -pcre /mnt
> qgoupid rfer excl max_rfer max_excl parent child
> -------- ---- ---- -------- -------- ------ -----
> 0/5 16.00KiB 16.00KiB none none --- ---
> 0/257 1016.00KiB 16.00KiB none none --- ---
> 0/258 1016.00KiB 16.00KiB none none --- ---
> 1/0 1016.00KiB 16.00KiB none none --- ---
> ^^^^^^^^^^ ^^^^^^^^ not cleared
> ------
>
> [CAUSE]
> Before rescan we call qgroup_rescan_zero_tracking() to zero out all
> qgroups' accounting numbers.
>
> However we don't mark all these qgroups dirty, but rely on rescan to
> mark qgroup dirty.
>
> If we have high level qgroup but without any child (orphan group), it
> won't be marked dirty during rescan, since we can reach that qgroup.
>
> This will cause QGROUP_INFO item of orphan qgroups never updated in
> quota tree, thus its number will stay the same in "btrfs qgroup show"
> output.
>
> [FIX]
> Just mark all qgroup dirty in qgroup_rescan_zero_tracking(), so even we
> have orphan qgroups their QGROUP_INFO item will still get updated during
> rescan.
>
> Reported-by: Misono Tomohiro <misono.tomoh...@jp.fujitsu.com>
> Signed-off-by: Qu Wenruo <w...@suse.com>
DOesn't this warrant an xfstests as well ?
> ---
> fs/btrfs/qgroup.c | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/fs/btrfs/qgroup.c b/fs/btrfs/qgroup.c
> index 48c1c3e7baf3..5a5372b33d96 100644
> --- a/fs/btrfs/qgroup.c
> +++ b/fs/btrfs/qgroup.c
> @@ -2864,6 +2864,7 @@ qgroup_rescan_zero_tracking(struct btrfs_fs_info
> *fs_info)
> qgroup->rfer_cmpr = 0;
> qgroup->excl = 0;
> qgroup->excl_cmpr = 0;
> + qgroup_dirty(fs_info, qgroup);
> }
> spin_unlock(&fs_info->qgroup_lock);
> }
>
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