Re: [PATCH 07/13] xfs: Convert to use invalidate_lock

Jan Kara
2021-05-26T10:18:44Z

On Tue 25-05-21 14:37:29, Darrick J. Wong wrote:
> On Tue, May 25, 2021 at 03:50:44PM +0200, Jan Kara wrote:
> > Use invalidate_lock instead of XFS internal i_mmap_lock. The intended
> > purpose of invalidate_lock is exactly the same. Note that the locking in
> > __xfs_filemap_fault() slightly changes as filemap_fault() already takes
> > invalidate_lock.
> >
> > Reviewed-by: Christoph Hellwig <hch@lst.de>
> > CC: <linux-xfs@vger.kernel.org>
> > CC: "Darrick J. Wong" <darrick.wong@oracle.com>
>
> It's djwong@kernel.org now.

OK, updated.

> > @@ -355,8 +358,11 @@ xfs_isilocked(
> >
> > if (lock_flags & (XFS_MMAPLOCK_EXCL|XFS_MMAPLOCK_SHARED)) {
> > if (!(lock_flags & XFS_MMAPLOCK_SHARED))
> > - return !!ip->i_mmaplock.mr_writer;
> > - return rwsem_is_locked(&ip->i_mmaplock.mr_lock);
> > + return !debug_locks ||
> > + lockdep_is_held_type(
> > + &VFS_I(ip)->i_mapping->invalidate_lock,
> > + 0);
> > + return rwsem_is_locked(&VFS_I(ip)->i_mapping->invalidate_lock);
>
> This doesn't look right...
>
> If lockdep is disabled, we always return true for
> xfs_isilocked(ip, XFS_MMAPLOCK_EXCL) even if nobody holds the lock?
>
> Granted, you probably just copy-pasted from the IOLOCK_SHARED clause
> beneath it. Er... oh right, preichl was messing with all that...
>
> https://lore.kernel.org/linux-xfs/20201016021005.548850-2-preichl@redhat.com/

Indeed copy-paste programming ;) It certainly makes the assertions happy
but useless. Should I pull the patch you reference into the series? It
seems to have been uncontroversial and reviewed. Or will you pull the
series to xfs tree so I can just rebase on top?

Honza
--
Jan Kara <jack@suse.com>
SUSE Labs, CR