Re: [ANNOUNCE] bcachefs!

Ming Lin
2015-07-17T23:36:22Z

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@kernel.org> 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