btrfs receive: could not find parent subvolume

btrfs receive: could not find parent subvolume

[Marc MERLIN]

While debugging a btrfs send/receive slow problem, I now getting this:
legolas:/mnt/btrfs_pool1# btrfs send -p tmp_ggm_daily_ro.20140917_06:29:58 tmp_ggm_daily_ro.20140918_02:48:24 | ssh gargamel btrfs receive -v /mnt/btrfs_pool2/backup/debian64/legolas
At subvol tmp_ggm_daily_ro.20140918_02:48:24
At snapshot tmp_ggm_daily_ro.20140918_02:48:24
receiving snapshot tmp_ggm_daily_ro.20140918_02:48:24 uuid=5d1f0454-1be3-b648-9ea5-dc427cd62d98, ctransid=310713 parent_uuid=d86e69bf-e17f-7f4c-bfb7-e571d5824687, parent_ctransid=308332
ERROR: could not find parent subvolume

The parent is there on the other side, but UUID is different:
gargamel:/mnt/btrfs_pool2/backup/debian64/legolas# btrfs subvolume show tmp_ggm_daily_ro.20140917_06:29:58
/mnt/btrfs_pool2/backup/debian64/legolas/tmp_ggm_daily_ro.20140917_06:29:58
        Name:                   tmp_ggm_daily_ro.20140917_06:29:58
        uuid:                   3d424a2b-69da-244c-bfcc-c283f9cc1f34
        Parent uuid:            05d3b9be-bfe2-bb4a-9f6a-64b9d44896c7
        Creation time:          2014-09-17 06:30:01
        Object ID:              7873
        Generation (Gen):       83621
        Gen at creation:        83476
        Parent:                 263
        Top Level:              263
        Flags:                  -
        Snapshot(s):

Now it seems that the UUID is different on all my snapshots created by
btrfs send, so maybe it doesn't match UUID?

Given that, what is btrfs receive using to get a match?

Thanks,
Marc
-- 
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Re: btrfs receive: could not find parent subvolume

[Hugo Mills]

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On Thu, Sep 18, 2014 at 08:27:18AM -0700, Marc MERLIN wrote:
> While debugging a btrfs send/receive slow problem, I now getting this:
> legolas:/mnt/btrfs_pool1# btrfs send -p tmp_ggm_daily_ro.20140917_06:29:58 tmp_ggm_daily_ro.20140918_02:48:24 | ssh gargamel btrfs receive -v /mnt/btrfs_pool2/backup/debian64/legolas
> At subvol tmp_ggm_daily_ro.20140918_02:48:24
> At snapshot tmp_ggm_daily_ro.20140918_02:48:24
> receiving snapshot tmp_ggm_daily_ro.20140918_02:48:24 uuid=5d1f0454-1be3-b648-9ea5-dc427cd62d98, ctransid=310713 parent_uuid=d86e69bf-e17f-7f4c-bfb7-e571d5824687, parent_ctransid=308332
> ERROR: could not find parent subvolume
> 
> The parent is there on the other side, but UUID is different:
> gargamel:/mnt/btrfs_pool2/backup/debian64/legolas# btrfs subvolume show tmp_ggm_daily_ro.20140917_06:29:58
> /mnt/btrfs_pool2/backup/debian64/legolas/tmp_ggm_daily_ro.20140917_06:29:58
>         Name:                   tmp_ggm_daily_ro.20140917_06:29:58
>         uuid:                   3d424a2b-69da-244c-bfcc-c283f9cc1f34
>         Parent uuid:            05d3b9be-bfe2-bb4a-9f6a-64b9d44896c7
>         Creation time:          2014-09-17 06:30:01
>         Object ID:              7873
>         Generation (Gen):       83621
>         Gen at creation:        83476
>         Parent:                 263
>         Top Level:              263
>         Flags:                  -
>         Snapshot(s):
> 
> Now it seems that the UUID is different on all my snapshots created by
> btrfs send, so maybe it doesn't match UUID?
> 
> Given that, what is btrfs receive using to get a match?

   There's a "recieved UUID" field on each subvolume. I posted a patch
to userspace a couple of weeks ago which adds a -R option to show it.
I don't think it's filtered through David's backlog yet.

   Hugo.

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Re: btrfs receive: could not find parent subvolume

[Marc MERLIN]

On Thu, Sep 18, 2014 at 04:39:34PM +0100, Hugo Mills wrote:
> > Now it seems that the UUID is different on all my snapshots created by
> > btrfs send, so maybe it doesn't match UUID?
> > 
> > Given that, what is btrfs receive using to get a match?
> 
>    There's a "recieved UUID" field on each subvolume. I posted a patch
> to userspace a couple of weeks ago which adds a -R option to show it.
> I don't think it's filtered through David's backlog yet.

Ah, thanks for that.

Now I wonder why the parent read only snapshot with the same name
on both sides (created by btrfs send) suddenly have a UUID mismatch.

Marc
-- 
"A mouse is a device used to point at the xterm you want to type in" - A.S.R.
Microsoft is to operating systems ....
                                      .... what McDonalds is to gourmet cooking
Home page: http://marc.merlins.org/                         | PGP 1024R/763BE901