On Tue, Oct 17, 2023 at 08:48:19PM +0200, Christoph Hellwig wrote: > From: Christian Brauner <brauner@xxxxxxxxxx> > > BLKPG_DEL_PARTITION refuses to delete partitions that still have > openers, i.e., that has an elevated @bdev->bd_openers count. If a device > is claimed by setting @bdev->bd_holder and @bdev->bd_holder_ops > @bdev->bd_openers and @bdev->bd_holders are incremented. > @bdev->bd_openers is effectively guaranteed to be >= @bdev->bd_holders. > So as long as @bdev->bd_openers isn't zero we know that this partition > is still in active use and that there might still be @bdev->bd_holder > and @bdev->bd_holder_ops set. > > The only current example is @fs_holder_ops for filesystems. But that > means bdev_mark_dead() which calls into > bdev->bd_holder_ops->mark_dead::fs_bdev_mark_dead() is a nop. As long as > there's an elevated @bdev->bd_openers count we can't delete the > partition and if there isn't an elevated @bdev->bd_openers count then > there's no @bdev->bd_holder or @bdev->bd_holder_ops. > > So simply open-code what we need to do. This gets rid of one more > instance where we acquire s_umount under @disk->open_mutex. > > Link: https://lore.kernel.org/r/20231016-fototermin-umriss-59f1ea6c1fe6@brauner > Reviewed-by: Christoph Hellwig <hch@xxxxxx> > Reviewed-by: Jan Kara <jack@xxxxxxx> > Reviewed-by: Jens Axboe <axboe@xxxxxxxxx> > Signed-off-by: Christian Brauner <brauner@xxxxxxxxxx> > Signed-off-by: Christoph Hellwig <hch@xxxxxx> inc/dec(part->bd_openers) is always done with ->open_mutex held, so this change is correct. Reviewed-by: Ming Lei <ming.lei@xxxxxxxxxx> Thanks, Ming
