Re: [PATCH 1/5] vfs: Add additional owner identifier

[Dmitry Monakhov <dmonakhov@openvz.org>]

Christoph Hellwig <hch@infradead.org> writes:

> On Thu, Mar 04, 2010 at 09:34:33PM +0300, Dmitry Monakhov wrote:
>> This patch add project inode identifier. Project ID may be used as
>> auxiliary owner specifier in addition to standard uid/gid.
>
> There's really no reason to make this a config option.
Project id feature is not likely to be widely used (i hope only 
at the beginning). Personally this is not bad to avoid config option.
At least we will have many new users for free. But I predict
many angry voices against enabling this feature by default.
Look, we even have CONFIG_BLOCK option at the time when this option
is enabled in 99.99% of systems.

Let's ask Jan an Al:
Will they accept genetic projectid support without appropriate config option?
>  And xattrs
> are a rather bad interfaces to this, so even if a filesystem has to
> resort to implement the project ID this way, this should be hidden
> inside the filesystem.
Only one question "Why not?".
I've tried to count pro and contra options.
*PRO*
 1) xattr interface already available, we don't have to invent a new one
 2) xattrs are supported by most of backup tools and other fs-related
    tools.
 3) xattr interface is rather simple and flexible. Filesystem is free
    to store it's projectid whenever it likes to, xattr is just an
    manipulation interface.
*CONTRA*
 1) XATTR_CREATE/XATTR_REPLACE is useless for project id since
    inode is belongs to default project (id == 0)