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Date: Fri, 11 May 2018 20:56:17 +0100
From: Al Viro <viro@ZenIV.linux.org.uk>
To: Dave Chinner <david@fromorbit.com>
Cc: linux-fsdevel@vger.kernel.org,
        Linus Torvalds <torvalds@linux-foundation.org>
Subject: Re: [RFC][PATCH] do d_instantiate/unlock_new_inode combinations
 safely
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On Fri, May 11, 2018 at 01:00:29PM +1000, Dave Chinner wrote:
> On Fri, May 11, 2018 at 03:18:43AM +0100, Al Viro wrote:
> > On Fri, May 11, 2018 at 11:32:08AM +1000, Dave Chinner wrote:
> > 
> > > i.e. we already have code in xfs_setup_inode() that sets the xfs
> > > inode ILOCK rwsem dir/non-dir lockdep class before the new inode is
> > > unlocked - we could just do the i_rwsem lockdep setup there, too.
> > 
> > ... which would suffice -
> > 
> >         if (S_ISDIR(inode->i_mode)) {
> >                 struct file_system_type *type = inode->i_sb->s_type;
> > 
> >                 /* Set new key only if filesystem hasn't already changed it */
> >                 if (lockdep_match_class(&inode->i_rwsem, &type->i_mutex_key)) {
> > 
> > in lockdep_annotate_inode_mutex_key() would make sure that ->i_rwsem will be
> > left alone by unlock_new_inode().
> 
> Ok, If you are happy with XFs doing that, I'll put together a patch
> and send it out.

That should probably go through xfs tree - no impact outside of fs/xfs...