On Wed, Nov 25, 2020 at 03:20:23PM -0500, Tejun Heo wrote: > Agreed. It'd be nice to replace the stale comment. I've updated the comment. > > Jan added lookup_sem in commit 56c0908c855afbb to prevent a three way > > race between del_gendisk and blkdev_open due to the weird bdev vs > > gendisk lifetime rules. None of that can happen with the new lookup > > scheme. > > Understood. I think it'd be worthwhile to note that in the commit log. So after the idea of just holding a disk reference from each bdev did not work out very well I've reworked this a bit, and lookup_sem stays, but becomes global to protect the disk lookup (similar to the previous global bdev_map_lock).
