linux-ext4 - Re: [PATCH 03/11] mm: Protect operations adding pages to page cache with invalidate

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Date:   Thu, 13 May 2021 19:49:35 +0200
From:   Jan Kara <jack@...e.cz>
To:     Matthew Wilcox <willy@...radead.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>
Subject: Re: [PATCH 03/11] mm: Protect operations adding pages to page cache
 with invalidate_lock

On Wed 12-05-21 15:20:44, Matthew Wilcox wrote:
> On Wed, May 12, 2021 at 03:46:11PM +0200, Jan Kara wrote:
> 
> > diff --git a/mm/truncate.c b/mm/truncate.c
> > index 57a618c4a0d6..93bde2741e0e 100644
> > --- a/mm/truncate.c
> > +++ b/mm/truncate.c
> > @@ -415,7 +415,7 @@ EXPORT_SYMBOL(truncate_inode_pages_range);
> >   * @mapping: mapping to truncate
> >   * @lstart: offset from which to truncate
> >   *
> > - * Called under (and serialised by) inode->i_rwsem.
> > + * Called under (and serialised by) inode->i_rwsem and inode->i_mapping_rwsem.
> 
> mapping->invalidate_lock, surely?

Right, thanks for noticing. 

> And could we ask lockdep to assert this for us instead of just a comment?

That's the plan but currently it would trip for filesystems unaware of
invalidate_lock. Once all filesystems are converted I plan to transform the
comments into actual asserts. In this series I aim at fixing the data
corruption issues, I plan the cleanups for later...

								Honza

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