Re: [PATCH 1/2] Add new spin_lock for i_flags of xfs_inode [try #2]

From: Nathan Scott
Date: Thu Aug 24 2006 - 01:43:51 EST


On Thu, Aug 24, 2006 at 03:42:45PM +1000, Nathan Scott wrote:
> On Wed, Aug 23, 2006 at 09:38:17PM -0700, Andrew Morton wrote:
> > On Wed, 23 Aug 2006 20:12:51 +0900
> > Masayuki Saito <m-saito@xxxxxxxxxxxxxx> wrote:
> >
> > > It is the problem that i_flags of xfs_inode has no consistent
> > > locking protection.
> > >
> > > For the reason, I define a new spin_lock(i_flags_lock) for i_flags
> > > of xfs_inode. And I add this spin_lock for appropriate places.
> >
> > You could simply use inode.i_lock for this. i_lock is a general-purpose
> > per-inode lock. Its mandate is "use it for whatever you like, but it must
> > always be `innermost'"
>
> Sounds spot on for our needs here, and has the added benefit of
> not increasing the size of the inode (as well as not adding to
> our locking complexity). Thanks!

Oh, except that the generic inode has a different lifecycle to the
xfs_inode_t, which is going to prevent using this. Doh. I had also
looked at the other xfs_inode locks before, but not seen an easy way
to piggyback on those... perhaps a way could be found though.

cheers.

--
Nathan
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