* Why isnt NOCOW attributes propogated on snapshot transfers?
@ 2017-10-15 1:19 Cerem Cem ASLAN
2017-10-16 0:51 ` Qu Wenruo
2017-10-16 13:28 ` David Sterba
0 siblings, 2 replies; 4+ messages in thread
From: Cerem Cem ASLAN @ 2017-10-15 1:19 UTC (permalink / raw)
To: linux-btrfs
`btrfs send | btrfs receive` removes NOCOW attributes. Is it a bug or
a feature? If it's a feature, how can we keep these attributes if we
need to?
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: Why isnt NOCOW attributes propogated on snapshot transfers?
2017-10-15 1:19 Why isnt NOCOW attributes propogated on snapshot transfers? Cerem Cem ASLAN
@ 2017-10-16 0:51 ` Qu Wenruo
2017-10-16 13:28 ` David Sterba
1 sibling, 0 replies; 4+ messages in thread
From: Qu Wenruo @ 2017-10-16 0:51 UTC (permalink / raw)
To: Cerem Cem ASLAN, linux-btrfs
On 2017年10月15日 09:19, Cerem Cem ASLAN wrote:
> `btrfs send | btrfs receive` removes NOCOW attributes. Is it a bug or
> a feature? If it's a feature, how can we keep these attributes if we
> need to?
It seems that, current send doesn't have support for extra inode flags.
Send can only send out c/m/atime, uid/gid and xattr.
Since NODATACOW is stored in inode item flags, not xattr, so it's not
supported yet.
Thanks,
Qu
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^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: Why isnt NOCOW attributes propogated on snapshot transfers?
2017-10-15 1:19 Why isnt NOCOW attributes propogated on snapshot transfers? Cerem Cem ASLAN
2017-10-16 0:51 ` Qu Wenruo
@ 2017-10-16 13:28 ` David Sterba
2017-10-16 15:59 ` Graham Cobb
1 sibling, 1 reply; 4+ messages in thread
From: David Sterba @ 2017-10-16 13:28 UTC (permalink / raw)
To: Cerem Cem ASLAN; +Cc: linux-btrfs
On Sun, Oct 15, 2017 at 04:19:23AM +0300, Cerem Cem ASLAN wrote:
> `btrfs send | btrfs receive` removes NOCOW attributes. Is it a bug or
> a feature? If it's a feature, how can we keep these attributes if we
> need to?
This is a known defficiency of send protocol v1. And there are more,
listed on
https://btrfs.wiki.kernel.org/index.php/Design_notes_on_Send/Receive#Send_stream_v2_draft
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: Why isnt NOCOW attributes propogated on snapshot transfers?
2017-10-16 13:28 ` David Sterba
@ 2017-10-16 15:59 ` Graham Cobb
0 siblings, 0 replies; 4+ messages in thread
From: Graham Cobb @ 2017-10-16 15:59 UTC (permalink / raw)
To: linux-btrfs
On 16/10/17 14:28, David Sterba wrote:
> On Sun, Oct 15, 2017 at 04:19:23AM +0300, Cerem Cem ASLAN wrote:
>> `btrfs send | btrfs receive` removes NOCOW attributes. Is it a bug or
>> a feature? If it's a feature, how can we keep these attributes if we
>> need to?
>
> This is a known defficiency of send protocol v1. And there are more,
> listed on
> https://btrfs.wiki.kernel.org/index.php/Design_notes_on_Send/Receive#Send_stream_v2_draft
It is not mentioned on the list (and I haven't tested to find out)...
but if xattr are supported in the V1 protocol, any chance of `send`
converting these file flags to xattr, and `receive` converting back? No
need for a protocol bump and would even preserve the information
(although not the effect) in the case of an old receiver.
^ permalink raw reply [flat|nested] 4+ messages in thread
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2017-10-15 1:19 Why isnt NOCOW attributes propogated on snapshot transfers? Cerem Cem ASLAN
2017-10-16 0:51 ` Qu Wenruo
2017-10-16 13:28 ` David Sterba
2017-10-16 15:59 ` Graham Cobb
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