linux-ext4 - Re: [PATCH 07/13] xfs: Convert to use invalidate

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Date:   Wed, 26 May 2021 12:18:40 +0200
From:   Jan Kara <jack@...e.cz>
To:     "Darrick J. Wong" <djwong@...nel.org>
Cc:     Jan Kara <jack@...e.cz>, linux-fsdevel@...r.kernel.org,
        Christoph Hellwig <hch@...radead.org>,
        Dave Chinner <david@...morbit.com>, ceph-devel@...r.kernel.org,
        Chao Yu <yuchao0@...wei.com>,
        Damien Le Moal <damien.lemoal@....com>,
        "Darrick J. Wong" <darrick.wong@...cle.com>,
        Jaegeuk Kim <jaegeuk@...nel.org>,
        Jeff Layton <jlayton@...nel.org>,
        Johannes Thumshirn <jth@...nel.org>,
        linux-cifs@...r.kernel.org, linux-ext4@...r.kernel.org,
        linux-f2fs-devel@...ts.sourceforge.net, linux-mm@...ck.org,
        linux-xfs@...r.kernel.org, Miklos Szeredi <miklos@...redi.hu>,
        Steve French <sfrench@...ba.org>, Ted Tso <tytso@....edu>,
        Matthew Wilcox <willy@...radead.org>,
        Christoph Hellwig <hch@....de>
Subject: Re: [PATCH 07/13] xfs: Convert to use invalidate_lock

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@....de>
> > CC: <linux-xfs@...r.kernel.org>
> > CC: "Darrick J. Wong" <darrick.wong@...cle.com>
> 
> It's djwong@...nel.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@...e.com>
SUSE Labs, CR