Re: [PATCH 2/8] block: move sync_blockdev from __blkdev_put to blkdev_put

Ming Lei
2021-05-19T09:32:21Z

On Wed, May 12, 2021 at 08:18:50AM +0200, Christoph Hellwig wrote:
> Do the early unlocked syncing even earlier to move more code out of
> the recursive path.
>
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
> fs/block_dev.c | 20 ++++++++++----------
> 1 file changed, 10 insertions(+), 10 deletions(-)
>
> diff --git a/fs/block_dev.c b/fs/block_dev.c
> index d053510d2f6a..95fde785dae7 100644
> --- a/fs/block_dev.c
> +++ b/fs/block_dev.c
> @@ -1553,16 +1553,6 @@ static void __blkdev_put(struct block_device *bdev, fmode_t mode, int for_part)
> struct gendisk *disk = bdev->bd_disk;
> struct block_device *victim = NULL;
>
> - /*
> - * Sync early if it looks like we're the last one. If someone else
> - * opens the block device between now and the decrement of bd_openers
> - * then we did a sync that we didn't need to, but that's not the end
> - * of the world and we want to avoid long (could be several minute)
> - * syncs while holding the mutex.
> - */
> - if (bdev->bd_openers == 1)
> - sync_blockdev(bdev);
> -
> mutex_lock_nested(&bdev->bd_mutex, for_part);
> if (for_part)
> bdev->bd_part_count--;
> @@ -1589,6 +1579,16 @@ void blkdev_put(struct block_device *bdev, fmode_t mode)
> {
> struct gendisk *disk = bdev->bd_disk;
>
> + /*
> + * Sync early if it looks like we're the last one. If someone else
> + * opens the block device between now and the decrement of bd_openers
> + * then we did a sync that we didn't need to, but that's not the end
> + * of the world and we want to avoid long (could be several minute)
> + * syncs while holding the mutex.
> + */
> + if (bdev->bd_openers == 1)
> + sync_blockdev(bdev);
> +

The early sync on disk is killed in case of closing partition, but there
shouldn't much dirty data on disk, so looks fine:

Reviewed-by: Ming Lei <ming.lei@redhat.com>

--
Ming