On Fri, Feb 24, 2017 at 11:15:17AM +0800, Guoqing Jiang wrote:
> Since we have switched to sync way to handle METADATA_UPDATED
> msg for md-cluster, then process_metadata_update is depended
> on mddev->thread->wqueue.
>
> With the new change, clustered raid could possible hang if
> array received a METADATA_UPDATED msg after array unregistered
> mddev->thread, so we need to stop clustered raid earlier
> than before.
>
> And this change should be safe for non-clustered raid since
> all writes are stopped before the destroy. Also in md_run,
> we activate the personality (pers->run()) before activating
> the bitmap (bitmap_create()). So it is pleasingly symmetric
> to stop the bitmap (bitmap_destroy()) before stopping the
> personality (__md_stop() calls pers->free()).
There is no patch 6. So I can't judge the purpose of the patch.
The patch changed behaviors. We only destroy bitmap with mode == 0, now we do it
even for mode == 2. Please specify why it's safe. The __md_stop will wait for
behind writes for example only with bitmap set, but the patch makes us not do
the wait.
> Reviewed-by: NeilBrown <neilb@xxxxxxxx>
> Signed-off-by: Guoqing Jiang <gqjiang@xxxxxxxx>
> ---
> drivers/md/md.c | 28 +++++++++++++++-------------
> 1 file changed, 15 insertions(+), 13 deletions(-)
>
> diff --git a/drivers/md/md.c b/drivers/md/md.c
> index 6e910d99c9c1..7bcc757386e1 100644
> --- a/drivers/md/md.c
> +++ b/drivers/md/md.c
> @@ -5582,8 +5582,8 @@ void md_stop(struct mddev *mddev)
> /* stop the array and free an attached data structures.
> * This is called from dm-raid
> */
> - __md_stop(mddev);
> bitmap_destroy(mddev);
> + __md_stop(mddev);
> if (mddev->bio_set)
> bioset_free(mddev->bio_set);
> }
> @@ -5696,6 +5696,20 @@ static int do_md_stop(struct mddev *mddev, int mode,
> set_disk_ro(disk, 0);
>
> __md_stop_writes(mddev);
> +
> + /*
> + * Destroy bitmap after all writes are stopped
> + */
> + bitmap_destroy(mddev);
> + if (mddev->bitmap_info.file) {
> + struct file *f = mddev->bitmap_info.file;
> + spin_lock(&mddev->lock);
> + mddev->bitmap_info.file = NULL;
> + spin_unlock(&mddev->lock);
> + fput(f);
> + }
> + mddev->bitmap_info.offset = 0;
> +
> __md_stop(mddev);
> mddev->queue->backing_dev_info.congested_fn = NULL;
>
> @@ -5720,19 +5734,7 @@ static int do_md_stop(struct mddev *mddev, int mode,
> */
> if (mode == 0) {
> pr_info("md: %s stopped.\n", mdname(mddev));
> -
> - bitmap_destroy(mddev);
> - if (mddev->bitmap_info.file) {
> - struct file *f = mddev->bitmap_info.file;
> - spin_lock(&mddev->lock);
> - mddev->bitmap_info.file = NULL;
> - spin_unlock(&mddev->lock);
> - fput(f);
> - }
> - mddev->bitmap_info.offset = 0;
> -
> export_array(mddev);
> -
> md_clean(mddev);
> if (mddev->hold_active == UNTIL_STOP)
> mddev->hold_active = 0;
> --
> 2.6.2
>
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