On Thu, Jun 18 2015 at 3:08pm -0400, Vivek Goyal <vgoyal@xxxxxxxxxx> wrote: > On Thu, Jun 18, 2015 at 02:16:19PM -0400, Mike Snitzer wrote: > > On Thu, Jun 18 2015 at 2:08pm -0400, > > Andi Kleen <andi@xxxxxxxxxxxxxx> wrote: > > > > > > Hmm, so you have a filesystem active on it too? > > > > > > I unmounted it before. > > > > > > > > > > > > Also the VG removal did not work of course. > > > > > > > > Once you resolve the filesystem piece, from vgremove man page: > > > > > > > > "vgremove allows you to remove one or more volume groups. If one or > > > > more physical volumes in the volume group are lost, consider vgreduce > > > > --removemissing to make the volume group metadata consistent again." > > > > > > Well in any case there should not be WARN()s. > > > > Yes well I don't even know what WARN_ON you're hitting. You're running > > a 4.0.4 fedora kernel. Which WARN_ON() is triggering? The > > WARN_ON_ONCE() in bdev_write_inode()? -- likely since the only caller of > > bdev_write_inode is __blkdev_put... > > > > /** > > * write_inode_now - write an inode to disk > > * @inode: inode to write to disk > > * @sync: whether the write should be synchronous or not > > * > > * This function commits an inode to disk immediately if it is dirty. This is > > * primarily needed by knfsd. > > * > > * The caller must either have a ref on the inode or must have set I_WILL_FREE. > > */ > > > > So I have no idea why bdev_write_inode() is using WARN_ON_ONCE.. makes > > since that write_inode_now() will fail if the disk no longer exists. SO > > the WARN_ON_ONCE seems misplaced. > > > > Git blame shows its all hch's fault: > > > > 564f00f6c (Christoph Hellwig 2015-01-14 10:42:33 +0100 57) WARN_ON_ONCE(write_inode_now(inode, true)); > > > > 564f00f6c block_dev: only write bdev inode on close > > I can reproduce it too in a Fedora 22 virtual machine. I just have to do > "umount <mnt>" after hot unplugging the virtIO disk. > > But it does not happen without lvm. If I create ext4 fs directly on > /dev/vda1, then when disk goes way, fs automatically gets unmounted. > > But same does not happen when /dev/vda1 is added to a volume group and > I carve out a logical volume and create and mount fs. > > In that case if I do umount after device has gone away, I can see above > WARN(). And it does seem to be coming from. write_inode_now() should fail.. the device is no longer there. No idea how virtio-blk avoids it, devil is in the blkdev refcount details I'm sure. > WARN_ON_ONCE(write_inode_now(inode, true)) > > If we failed to write back inode, then warning about it sounds right? A warning is fine.. not a WARN_ON(). Pretty alarming backtrace spew but maybe I'm missing something and DM's blkdev refcount mgmt couldn't trigger this WARN_ON()? I fail to see how to avoid it given the device isn't thre so write_inode_now() fails. > What's wrong with that? Should it be just a kernel log of level KERN_WARN > instead? Ideally, but I honestly don't have all the details paged in my head to say definitively. First need to answer how vitrio-blk isn't hitting this (and DM is). Could it be that __blkdev_put isn't getting called for virtio-blk!? -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
