On Fri, Jul 17, 2015 at 04:48:31PM -0700, Ming Lin wrote: > > On Fri, 2015-07-17 at 16:40 -0700, Kent Overstreet wrote: > > On Fri, Jul 17, 2015 at 04:35:55PM -0700, Ming Lin wrote: > > > > > > On Fri, 2015-07-17 at 16:17 -0700, Kent Overstreet wrote: > > > > On Wed, Jul 15, 2015 at 12:39:36AM -0700, Ming Lin wrote: > > > > > On Wed, Jul 15, 2015 at 12:15 AM, Ming Lin <mlin@xxxxxxxxxx> wrote: > > > > > > On Tue, 2015-07-14 at 23:58 -0700, Kent Overstreet wrote: > > > > > >> Can you strace it? > > > > > > > > > > > > Strange. Now error message changed. > > > > > > > > > > I mean sometimes it showed: > > > > > > > > > > mount: /dev/sdt already mounted or /mnt/ busy > > > > > > > > I have no idea what's going on, it works for me - is there anything unusual > > > > about your setup? what kind of block device is /dev/sdt? is there any chance > > > > there's another process that has it open? maybe try rebooting? > > > > > > It's a regular HDD. I tried rebooting several times. > > > > > > Now I try in qemu-kvm. Only the first time it can be mounted. > > > > > > On host: qemu-img create hdd1.img 20G > > > On guest: it's /dev/vda > > > > > > root@block:~# bcacheadm format -C /dev/vda > > > UUID: 4730ed95-4c57-42db-856c-dbce36085625 > > > Set UUID: e69ef0e0-0344-40d7-a6b1-c23d14745a32 > > > version: 6 > > > nbuckets: 40960 > > > block_size: 1 > > > bucket_size: 1024 > > > nr_in_set: 1 > > > nr_this_dev: 0 > > > first_bucket: 3 > > > > > > root@block:~# mount -t bcache /dev/vda /mnt/ > > > > > > root@block:~# mount |grep bcache > > > /dev/vda on /mnt type bcache (rw,relatime) > > > > > > root@block:~# reboot > > > > > > root@block:~# dmesg |grep -i bcache > > > [ 2.548754] bcache: bch_journal_replay() journal replay done, 1 keys in 1 entries, seq 3 > > > [ 2.636217] bcache: register_cache() registered cache device vda > > > > > > > > > root@block:~# mount -t bcache /dev/vda /mnt/ > > > mount: No such file or directory > > > > > > Now dmesg shows: > > > > > > bcache: bch_open_as_blockdevs() register_cache_set err device already registered > > > > Ohhhh. > > > > The cache set is getting registered by the udev hooks. We should be able to > > mount it anyways - same as you can mount any other fs in multiple locations. > > > > I won't be able to fix this for at least a couple days, but for now - just > > shut it down it via sysfs (echo 1 > /sys/fs/bcache/<uuid>/stop), then mount it. > > It works! > Any hint how to fix it? On udev or bcache-tool or kernel? > I'd like to fix it. The relevant code is in drivers/md/bcache/fs.c, bch_mount() -> bch_open_as_blockdevs(). Part of the problem is that bcachefs isn't able to use much of the normal generic mount path for block devices, partly because a fs can span multiple block devices (same as btrfs). I'm not sure the right way to fix it - it's going to take some thought, but we want to do something like "is it already open? just take a ref on the existing cache set". -- To unsubscribe from this list: send the line "unsubscribe linux-bcache" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
