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* [PATCH] btrfs: qgroup: Dirty all qgroups before rescan
@ 2018-08-09  7:03 Qu Wenruo
  2018-08-09  7:05 ` Nikolay Borisov
  0 siblings, 1 reply; 3+ messages in thread
From: Qu Wenruo @ 2018-08-09  7:03 UTC (permalink / raw)
  To: linux-btrfs

[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.tomohiro@jp.fujitsu.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
---
 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);
 }
-- 
2.18.0


^ permalink raw reply related	[flat|nested] 3+ messages in thread

end of thread, other threads:[~2018-08-09  9:33 UTC | newest]

Thread overview: 3+ messages (download: mbox.gz follow: Atom feed
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2018-08-09  7:03 [PATCH] btrfs: qgroup: Dirty all qgroups before rescan Qu Wenruo
2018-08-09  7:05 ` Nikolay Borisov
2018-08-09  7:09   ` Qu Wenruo

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