On Tue, Sep 13, 2016 at 4:11 PM, Nikolay Borisov <kernel@xxxxxxxx> wrote: > > > On 09/13/2016 04:30 PM, Ilya Dryomov wrote: > [SNIP] >> >> Hmm, it could be about whether it is able to do journal replay on >> mount. When you mount a snapshot, you get a read-only block device; >> when you mount a clone image, you get a read-write block device. >> >> Let's try this again, suppose image is foo and snapshot is snap: >> >> # fsfreeze -f /mnt >> >> # rbd snap create foo@snap >> # rbd map foo@snap >> /dev/rbd0 >> # file -s /dev/rbd0 >> # fsck.ext4 -n /dev/rbd0 >> # mount /dev/rbd0 /foo >> # umount /foo >> <full dmesg> >> # file -s /dev/rbd0 >> # fsck.ext4 -n /dev/rbd0 >> >> # rbd clone foo@snap bar >> $ rbd map bar >> /dev/rbd1 >> # file -s /dev/rbd1 >> # fsck.ext4 -n /dev/rbd1 >> # mount /dev/rbd1 /bar >> # umount /bar >> <full dmesg> >> # file -s /dev/rbd1 >> # fsck.ext4 -n /dev/rbd1 >> >> Could you please provide the output for the above? > > Here you go : http://paste.ubuntu.com/23173721/ OK, so that explains it: the frozen filesystem is "needs journal recovery", so mounting it off of read-only block device leads to errors. root@alxc13:~# fsfreeze -f /var/lxc/c11579 root@alxc13:~# rbd snap create rbd/c11579@snap_test root@alxc13:~# rbd map c11579@snap_test /dev/rbd151 root@alxc13:~# fsfreeze -u /var/lxc/c11579 root@alxc13:~# file -s /dev/rbd151 /dev/rbd151: Linux rev 1.0 ext4 filesystem data (needs journal recovery) (extents) (large files) (huge files) Now, to isolate the problem, the easiest would probably be to try to reproduce it with loop devices. Can you try dding one of these images to a file, make sure that the filesystem is clean, losetup + mount, freeze, make a "snapshot" with cp and losetup -r + mount? Try sticking file -s before unfreeze and also compare md5sums: root@alxc13:~# fsfreeze -f /var/lxc/c11579 <md5sum for /var/lxc/c11579 device> root@alxc13:~# rbd snap create rbd/c11579@snap_test root@alxc13:~# rbd map c11579@snap_test <md5sum for /var/lxc/c11579 device> <md5sum for /dev/rbd151> root@alxc13:~# file -s /dev/rbd151 root@alxc13:~# fsfreeze -u /var/lxc/c11579 <md5sum for /var/lxc/c11579 device> <md5sum for /dev/rbd151> root@alxc13:~# file -s /dev/rbd151 Thanks, Ilya _______________________________________________ ceph-users mailing list ceph-users@xxxxxxxxxxxxxx http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
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