On Wed, Mar 7, 2018 at 6:49 PM, Liu Bo <bo.li....@oracle.com> wrote: > Hi, > > In the following steps[1], if <parent> on receiver side has got > changed via 'btrfs property set', then after doing incremental > updates, receiver gets a different snapshot from what sender has sent. > > The reason behind it is that there is no change about file 'foo' in > the send stream, such that receiver simply creates a snapshot of > <parent> on its side with nothing to apply from the send stream. > > A possible way to avoid this is to check rtransid and ctranid of > <parent> on receiver side, but I'm not very sure whether the current > behavior is made deliberately, does anyone have an idea? > > Thanks, > > -liubo > > [1]: > $ btrfs sub create /mnt/send/sub > $ touch /mnt/send/sub/foo > $ btrfs sub snap -r /mnt/send/sub /mnt/send/parent > > # send parent out > $ btrfs send /mnt/send/parent | btrfs receive /mnt/recv/ > > # change parent and file under it > $ btrfs property set -t subvol /mnt/recv/parent ro false > $ truncate -s 4096 /mnt/recv/parent/foo > > $ btrfs sub snap -r /mnt/send/sub /mnt/send/update > $ btrfs send -p /mnt/send/parent /mnt/send/update | btrfs receive /mnt/recv > > $ ls -l /mnt/send/update > total 0 > -rw-r--r-- 1 root root 0 Mar 6 11:13 foo > > $ ls -l /mnt/recv/update > total 0 > -rw-r--r-- 1 root root 4096 Mar 6 11:14 foo
Interesting. I wasn't aware of that and I'm surprised too, I wouldn't expect that behaviour (and I must see the code to figure out why it behaves like that). No idea if it's intentional or not, but at a first glance it seems not. > > -- > To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in > the body of a message to majord...@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html -- Filipe David Manana, “Whether you think you can, or you think you can't — you're right.” -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
