btrfs send/receive does not preserve +C (nocow) attribute

DISCUSSION Jakub Klinkovský 2 participants 2 messages Aug 6, 2014 Btrfs file system

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Jakub Klinkovský

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2014-08-06 15:57 UTC #0 lore raw

I've been testing btrfs send/receive, and to my surprise, the +C (nocow) attribute I have set on directory for virtual machines images is not preserved. Is this expected? Having found no information about this issue, I'm asking here.

Info:

$ uname -a
Linux asusntb 3.15.8-1-ARCH #1 SMP PREEMPT Fri Aug 1 08:51:42 CEST 2014 x86_64 GNU/Linux
$ btrfs --version
Btrfs v3.14.2-dirty

Both source and target btrfs filesystems are mounted with the same mount options:
rw,nosuid,nodev,noatime,compress=lzo,space_cache,autodefrag,commit=60

$ lsattr ~/virtual_machines/
---------------C virtual_machines/archlinux-btrfs.raw
---------------C virtual_machines/archlinux.raw
---------------C virtual_machines/winxp.raw

$ lsattr /media/backup/virtual_machines/2014-08-06/
---------------- /media/backup/virtual_machines/2014-08-06/archlinux-btrfs.raw
---------------- /media/backup/virtual_machines/2014-08-06/archlinux.raw
---------------- /media/backup/virtual_machines/2014-08-06/winxp.raw

Regards,

--
jlk

Juan Orti Alcaine

2014-08-06 16:29 UTC #1 lore raw

Quoted 26 lines · El Miércoles, 6 de agosto de 2014 17:56:52 Jakub Klinkovský escribió:

I've been testing btrfs send/receive, and to my surprise, the +C (nocow) attribute I have set on directory for virtual machines images is not preserved. Is this expected? Having found no information about this issue, I'm asking here.
Info:
$ uname -a
Linux asusntb 3.15.8-1-ARCH #1 SMP PREEMPT Fri Aug 1 08:51:42 CEST 2014
x86_64 GNU/Linux $ btrfs --version
Btrfs v3.14.2-dirty
Both source and target btrfs filesystems are mounted with the same mount options:
rw,nosuid,nodev,noatime,compress=lzo,space_cache,autodefrag,commit=60
$ lsattr ~/virtual_machines/
---------------C virtual_machines/archlinux-btrfs.raw
---------------C virtual_machines/archlinux.raw
---------------C virtual_machines/winxp.raw
$ lsattr /media/backup/virtual_machines/2014-08-06/
----------------
/media/backup/virtual_machines/2014-08-06/archlinux-btrfs.raw
---------------- /media/backup/virtual_machines/2014-08-06/archlinux.raw
---------------- /media/backup/virtual_machines/2014-08-06/winxp.raw

Quoted 4 lines

Regards,
--
jlk

Nor do file capabilities get preserved:
https://bugzilla.kernel.org/show_bug.cgi?id=68891