On Tue, Oct 17, 2023 at 08:48:20PM +0200, Christoph Hellwig wrote: > From: Christian Brauner <brauner@xxxxxxxxxx> > > The logic for disk->open_partitions is: > > blkdev_get_by_*() > -> bdev_is_partition() > -> blkdev_get_part() > -> blkdev_get_whole() // bdev_whole->bd_openers++ > -> if (part->bd_openers == 0) > disk->open_partitions++ > part->bd_openers > > In other words, when we first claim/open a partition we increment > disk->open_partitions and only when all part->bd_openers are closed will > disk->open_partitions be zero. That should mean that > disk->open_partitions is always > 0 as long as there's anyone that > has an open partition. > > So the check for disk->open_partitions should meand that we can never > remove an active partition that has a holder and holder ops set. Assert > that in the code. The main disk isn't removed so that check doesn't work > for disk->part0 which is what we want. After all we only care about > partition not about the main disk. > > Signed-off-by: Christian Brauner <brauner@xxxxxxxxxx> 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
