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 <rak...@tuxera.com> > > > > 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.
