On Tue, Apr 16, 2024 at 11:29 PM Mike Snitzer <snitzer@xxxxxxxxxx> wrote:
>
> From: Ming Lei <ming.lei@xxxxxxxxxx>
>
> 'dmsetup remove' and 'dmsetup remove_all' require synchronous bdev
> release. Otherwise dm_lock_for_deletion() may return -EBUSY if the open
> count is > 0, because the open count is dropped in dm_blk_close()
> which occurs after fput() completes.
>
> So if dm_blk_close() is delayed because of asynchronous fput(), this
> device mapper device is skipped during remove, which is a regression.
>
> Fix the issue by using __fput_sync().
>
> Also: DM device removal has long supported being made asynchronous by
> setting the DMF_DEFERRED_REMOVE flag on the DM device. So leverage
> using async fput() in close_table_device() if DMF_DEFERRED_REMOVE flag
> is set.
>
> Reported-by: Zhong Changhui <czhong@xxxxxxxxxx>
> Fixes: a28d893eb327 ("md: port block device access to file")
> Suggested-by: Christian Brauner <brauner@xxxxxxxxxx>
> Signed-off-by: Ming Lei <ming.lei@xxxxxxxxxx>
> [snitzer: editted commit header, use fput() if DMF_DEFERRED_REMOVE set]
> Signed-off-by: Mike Snitzer <snitzer@xxxxxxxxxx>
> ---
> drivers/md/dm.c | 10 ++++++++--
> 1 file changed, 8 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/md/dm.c b/drivers/md/dm.c
> index 56aa2a8b9d71..7d0746b37c8e 100644
> --- a/drivers/md/dm.c
> +++ b/drivers/md/dm.c
> @@ -765,7 +765,7 @@ static struct table_device *open_table_device(struct mapped_device *md,
> return td;
>
> out_blkdev_put:
> - fput(bdev_file);
> + __fput_sync(bdev_file);
> out_free_td:
> kfree(td);
> return ERR_PTR(r);
> @@ -778,7 +778,13 @@ static void close_table_device(struct table_device *td, struct mapped_device *md
> {
> if (md->disk->slave_dir)
> bd_unlink_disk_holder(td->dm_dev.bdev, md->disk);
> - fput(td->dm_dev.bdev_file);
> +
> + /* Leverage async fput() if DMF_DEFERRED_REMOVE set */
> + if (unlikely(test_bit(DMF_DEFERRED_REMOVE, &md->flags)))
> + fput(td->dm_dev.bdev_file);
> + else
> + __fput_sync(td->dm_dev.bdev_file);
> +
> put_dax(td->dm_dev.dax_dev);
> list_del(&td->list);
> kfree(td);
> --
> 2.40.0
>
I tried to apply this patch and looks this issue has solved by this patch
