On Wed 26-01-22 16:50:39, Christoph Hellwig wrote:
> ->release is only called after all outstanding I/O has completed, so only
> freeze the queue when clearing the backing file of a live loop device.
>
> Signed-off-by: Christoph Hellwig <hch@xxxxxx>
Looks good. I was just wondering: Is there anything which prevents us from
moving blk_mq_freeze_queue() & blk_mq_unfreeze_queue() calls to
loop_clr_fd() around __loop_clr_fd() call?
Anyway feel free to add:
Reviewed-by: Jan Kara <jack@xxxxxxx>
Honza
> ---
> drivers/block/loop.c | 18 ++++++++++++------
> 1 file changed, 12 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/block/loop.c b/drivers/block/loop.c
> index d9a0e2205762f..fc0cdd1612b1d 100644
> --- a/drivers/block/loop.c
> +++ b/drivers/block/loop.c
> @@ -1110,7 +1110,7 @@ static int loop_configure(struct loop_device *lo, fmode_t mode,
> return error;
> }
>
> -static void __loop_clr_fd(struct loop_device *lo)
> +static void __loop_clr_fd(struct loop_device *lo, bool release)
> {
> struct file *filp;
> gfp_t gfp = lo->old_gfp_mask;
> @@ -1139,8 +1139,13 @@ static void __loop_clr_fd(struct loop_device *lo)
> if (test_bit(QUEUE_FLAG_WC, &lo->lo_queue->queue_flags))
> blk_queue_write_cache(lo->lo_queue, false, false);
>
> - /* freeze request queue during the transition */
> - blk_mq_freeze_queue(lo->lo_queue);
> + /*
> + * Freeze the request queue when unbinding on a live file descriptor and
> + * thus an open device. When called from ->release we are guaranteed
> + * that there is no I/O in progress already.
> + */
> + if (!release)
> + blk_mq_freeze_queue(lo->lo_queue);
>
> destroy_workqueue(lo->workqueue);
> loop_free_idle_workers(lo, true);
> @@ -1163,7 +1168,8 @@ static void __loop_clr_fd(struct loop_device *lo)
> /* let user-space know about this change */
> kobject_uevent(&disk_to_dev(lo->lo_disk)->kobj, KOBJ_CHANGE);
> mapping_set_gfp_mask(filp->f_mapping, gfp);
> - blk_mq_unfreeze_queue(lo->lo_queue);
> + if (!release)
> + blk_mq_unfreeze_queue(lo->lo_queue);
>
> disk_force_media_change(lo->lo_disk, DISK_EVENT_MEDIA_CHANGE);
>
> @@ -1201,7 +1207,7 @@ static void loop_rundown_workfn(struct work_struct *work)
> struct block_device *bdev = lo->lo_device;
> struct gendisk *disk = lo->lo_disk;
>
> - __loop_clr_fd(lo);
> + __loop_clr_fd(lo, true);
> kobject_put(&bdev->bd_device.kobj);
> module_put(disk->fops->owner);
> loop_rundown_completed(lo);
> @@ -1247,7 +1253,7 @@ static int loop_clr_fd(struct loop_device *lo)
> lo->lo_state = Lo_rundown;
> mutex_unlock(&lo->lo_mutex);
>
> - __loop_clr_fd(lo);
> + __loop_clr_fd(lo, false);
> loop_rundown_completed(lo);
> return 0;
> }
> --
> 2.30.2
>
--
Jan Kara <jack@xxxxxxxx>
SUSE Labs, CR
