Re: SELinux inode size gotcha in btrfs.

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

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On Tue, Feb 28, 2012 at 11:30:26AM +0000, Alex wrote:
> David Sterba <dave <at> jikos.cz> writes:
> 
> > 
> > That's right. Inode represented as btrfs_inode_item does not contain any
> > xattr fields, they're stored independently as a btrfs_dir_item of type
> > BTRFS_FT_XATTR . Due to the way the b-tree keys are built, the xattr
> > item key should be stored near the inode item key, that's for the tree
> > search side. The xattr data are always stored inline in the b-tree leaf.
> > 
> 
> 
> Thank you David and Hugo,
> 
> My bad on three counts:
> 1) My courtesy close seems to have gone missing.
>  Sorry and thank you for replying.
> 2) I, perhaps, should have pointed to
> https://wiki.debian.org/SELinux/Setup#Prerequisites
> _.28kernel_and_filesystems.29
> which gives a better explanation.

   Aaah, OK, that makes sense now. So: we don't have the issue over
xattr sizes at all. The main issue would then seem to be over
atomicity of writing xattrs -- I don't know what the APIs for this
look like, or whether we've implemented them, so I can't comment any
further on btrfs's suitability I'm afraid.

> 3) Made it clear that I wasn't attacking
>  XFS, It's my fs of (non /boot) choice
> for some years now; I'm exploring SELinux
>  (after the recent Linux conf au 2012
> talk) and know I have used inode size defaults
>  for my xfs init back in the day!

   I certainly didn't read it as such.

   Hugo.

-- 
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