On Mon, Dec 14, 2020 at 10:10:45AM +0000, fdman...@kernel.org wrote:
> +static bool rescan_should_stop(struct btrfs_fs_info *fs_info)
> +{
> + return btrfs_fs_closing(fs_info) ||
> + test_bit(BTRFS_FS_STATE_REMOUNTING, &fs_info->fs_state);
> +}
> +
> static void btrfs_qgroup_rescan_worker(struct btrfs_work *work)
> {
> struct btrfs_fs_info *fs_info = container_of(work, struct btrfs_fs_info,
> @@ -3198,6 +3204,7 @@ static void btrfs_qgroup_rescan_worker(struct
> btrfs_work *work)
> struct btrfs_trans_handle *trans = NULL;
> int err = -ENOMEM;
> int ret = 0;
> + bool stopped = false;
>
> path = btrfs_alloc_path();
> if (!path)
> @@ -3210,7 +3217,7 @@ static void btrfs_qgroup_rescan_worker(struct
> btrfs_work *work)
> path->skip_locking = 1;
>
> err = 0;
> - while (!err && !btrfs_fs_closing(fs_info)) {
> + while (!err && !(stopped = rescan_should_stop(fs_info))) {
> trans = btrfs_start_transaction(fs_info->fs_root, 0);
> if (IS_ERR(trans)) {
> err = PTR_ERR(trans);
> @@ -3253,7 +3260,7 @@ static void btrfs_qgroup_rescan_worker(struct
> btrfs_work *work)
> }
>
> mutex_lock(&fs_info->qgroup_rescan_lock);
> - if (!btrfs_fs_closing(fs_info))
> + if (!stopped)
> fs_info->qgroup_flags &= ~BTRFS_QGROUP_STATUS_FLAG_RESCAN;
> if (trans) {
> ret = update_qgroup_status_item(trans);
> @@ -3272,7 +3279,7 @@ static void btrfs_qgroup_rescan_worker(struct
> btrfs_work *work)
>
> btrfs_end_transaction(trans);
>
> - if (btrfs_fs_closing(fs_info)) {
> + if (stopped) {
Thinking aloud, this is slightly different as it uses the cached status
of fs_closing but there is mutex lock/unlock or transaction start/end
between the checks so the status could change.
But as the flow goes, we want to get fresh status in the while loop.
Once it stops because of the fs_closing or remount request, the
following code does the qgroup status update, wakeups, even tough this
means one more transaction. Remount needs to sync anyway and this should
be no problem.
