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

[Hugo Mills <hugo@carfax.org.uk>]

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On Tue, Nov 12, 2013 at 08:04:47PM +0000, Filipe David Manana wrote:
> 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).

   Why only that limited set? Is that limited by POSIX, or executive
fiat? Is there any likelihood of us getting an additional namespace?
(fs.* maybe?)

   Hugo.

> 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
> >

-- 
=== Hugo Mills: hugo@... carfax.org.uk | darksatanic.net | lug.org.uk ===
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    --- I write in C because using pointer arithmetic lets people ---    
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