On Fri, Oct 13, 2017 at 5:35 PM, Rakesh Pandit <rakesh@xxxxxxxxxx> wrote: > On Fri, Oct 13, 2017 at 07:58:09AM -0700, Christoph Hellwig wrote: >> On Fri, Oct 13, 2017 at 02:45:51PM +0200, Matias Bjørling wrote: >> > From: Rakesh Pandit <rakesh@xxxxxxxxxx> >> > >> > When a virtual block device is formatted and mounted after creating >> > with "nvme lnvm create... -t pblk", a removal from "nvm lnvm remove" >> > would result in this: >> > >> > 446416.309757] bdi-block not registered >> > [446416.309773] ------------[ cut here ]------------ >> > [446416.309780] WARNING: CPU: 3 PID: 4319 at fs/fs-writeback.c:2159 >> > __mark_inode_dirty+0x268/0x340 >> > >> > Ideally removal should return -EBUSY as block device is mounted after >> > formatting. This patch tries to address this checking if whole device >> > or any partition of it already mounted or not before removal. >> >> How is this different from any other block device that can be >> removed even if a file system is mounted? > > One can create many virtual block devices on top of physical using: > nvme lnvm create ... -t pblk > > And remove them using: > nvme lnvm remove > > Because the block devices are virtual in nature created by a program I was > expecting removal to tell me they are busy instead of bdi-block not registered > following by a WARNING (above). My use case was writing automatic test case > but I assumed this is useful in general. > >> >> > >> > Whole device is checked using "bd_super" member of block device. This >> > member is always set once block device has been mounted using a >> > filesystem. Another member "bd_part_count" takes care of checking any >> > if any partitions are under use. "bd_part_count" is only updated >> > under locks when partitions are opened or closed (first open and last >> > release). This at least does take care sending -EBUSY if removal is >> > being attempted while whole block device or any partition is mounted. >> > >> >> That's a massive layering violation, and a driver has no business >> looking at these fields. > > Okay, I didn't consider this earlier. I would suggest a revert for this. I see you've already done it. Thanks Jens.
