On Mon, Jul 21, 2025 at 08:47:12AM +0200, Christoph Hellwig wrote: > On Mon, Jul 21, 2025 at 09:20:27AM +0800, Zizhi Wo wrote: > > Sorry, disk_live() is only declared but not defined when CONFIG_BLOCK is > > not set... > > You can just add a if (IS_ENABLED(CONFIG_BLOCK)) check around it. > > > But the layering here feels wrong. sget_dev and it's helper operate > purely on the dev_t. Anything actually dealing with a block device / > gendisk should be in the helpers that otherwise use it. Either we add a lookup_bdev_alive() variant that checks whether the inode is still hashed when looking up the dev_t and we accept that this deals with the obvious cases and accept that this is racy... Or we add lookup_bdev_no_open() that returns the block device with the reference bumped, paired with lookup_bdev_put_no_open(). Afaiu, that would prevent deletion. We could even put this behind a guard(bdev_no_open)(fc->source). The reference count bump shouldn't matter there. Christoph?
