Re: [RFC PATCH] Btrfs: add support for inode properties

[Filipe David Manana <fdmanana@gmail.com>]

On Tue, Nov 12, 2013 at 7:24 PM, Goffredo Baroncelli <kreijack@libero.it> wrote:
> Hi Filipe,

Hi

>
> On 2013-11-12 14:42, Filipe David Borba Manana wrote:
>> This change adds infrastructure to allow for generic properties for
>> inodes via a new ioctl.
>
> I am sure that there is a valid reason, but I was not able to find it:
> why implement a new ioctl instead of using the *{set,get)xattr(2) syscall ?

Those require one of the following name prefixes: "user.",
"security.", "trusted." or "system.". Only "user." can be set from
user space and requires no special privileges/capabilities (if you
have the necessary permissions on the target inode).

It could be implemented via the "user." prefix, like
"user.btrfs.something" for example - but it can break user
applications if they use such prefix already, and we want to validate
the values set for such properties too.

>
> I noticed that you implemented the Compression properties set/get: is
> this from "chattr -c" ?

With chattr -c you can't specify the compression algorithm - it will
use the default (zlib) or the one you specified via mount options.

thanks

>
> [... cut other lines ... ]
>
> G.Baroncelli
>
> --
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-- 
Filipe David Manana,

"Reasonable men adapt themselves to the world.
 Unreasonable men adapt the world to themselves.
 That's why all progress depends on unreasonable men."