On 2018/07/26 18:15, Qu Wenruo wrote:
> Between btrfs_quota_enable() finished and rescan kicked in, there is a
> small window that quota status has (ON | INCONSISTENT) bits set but
> without RESCAN bits set.
>
> And transaction is committed inside the window and then power loss
> happens, we will have a quota tree with all qgroup numbers set to 0, and
> not RESCAN bit set.
>
> At next mount time, qgroup rescan will not kick in due to the missing of
> RESCAN bit, user needs to kick in rescan manually.
>
> This patch will fix it by setting RESCAN bit at btrfs_quota_enable(),
> so even after power loss we will still kick in rescan automatically.
>
> Suggested-by: Misono Tomohiro <misono.tomohiro@xxxxxxxxxxxxxx>
> Signed-off-by: Qu Wenruo <wqu@xxxxxxxx>
> ---
> fs/btrfs/qgroup.c | 5 +++--
> 1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/fs/btrfs/qgroup.c b/fs/btrfs/qgroup.c
> index c25dc47210a3..13c1c7dd278d 100644
> --- a/fs/btrfs/qgroup.c
> +++ b/fs/btrfs/qgroup.c
> @@ -930,7 +930,8 @@ int btrfs_quota_enable(struct btrfs_trans_handle *trans,
> btrfs_set_qgroup_status_generation(leaf, ptr, trans->transid);
> btrfs_set_qgroup_status_version(leaf, ptr, BTRFS_QGROUP_STATUS_VERSION);
> fs_info->qgroup_flags = BTRFS_QGROUP_STATUS_FLAG_ON |
> - BTRFS_QGROUP_STATUS_FLAG_INCONSISTENT;
> + BTRFS_QGROUP_STATUS_FLAG_INCONSISTENT |
> + BTRFS_QGROUP_STATUS_FLAG_RESCAN;
> btrfs_set_qgroup_status_flags(leaf, ptr, fs_info->qgroup_flags);
> btrfs_set_qgroup_status_rescan(leaf, ptr, 0);
>
> @@ -987,7 +988,7 @@ int btrfs_quota_enable(struct btrfs_trans_handle *trans,
> fs_info->quota_root = quota_root;
> set_bit(BTRFS_FS_QUOTA_ENABLED, &fs_info->flags);
> spin_unlock(&fs_info->qgroup_lock);
> - ret = qgroup_rescan_init(fs_info, 0, 1);
> + ret = qgroup_rescan_init(fs_info, 0, 0);
> if (!ret) {
> qgroup_rescan_zero_tracking(fs_info);
> btrfs_queue_work(fs_info->qgroup_rescan_workers,
>
This is what I think at first, but is it ok not holding fs_info->qgroup_ioctl_lock
in brfs_qgroup_rescan() as you concerned in previous thread?
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