Re: [RFCv3 7/7] iomap: Optimize data access patterns for filesystems with indirect mappings

From: Christoph Hellwig <hch@infradead.org>
To: Matthew Wilcox <willy@infradead.org>
Cc: Ritesh Harjani <ritesh.list@gmail.com>,
	"Darrick J. Wong" <djwong@kernel.org>,
	linux-ext4@vger.kernel.org, linux-xfs@vger.kernel.org,
	linux-fsdevel@vger.kernel.org,
	Ojaswin Mujoo <ojaswin@linux.ibm.com>, Jan Kara <jack@suse.cz>
Subject: Re: [RFCv3 7/7] iomap: Optimize data access patterns for filesystems with indirect mappings
Date: Fri, 26 Apr 2024 21:54:46 -0700	[thread overview]
Message-ID: <ZiyFFsPlgODpc-e3@infradead.org> (raw)
In-Reply-To: <Ziv-U8-Rt9md-Npv@casper.infradead.org>

On Fri, Apr 26, 2024 at 08:19:47PM +0100, Matthew Wilcox wrote:
> > ...One small problem which I see with this approach is - we might have
> > some non-zero value in ifs->r_b_p when ifs_free() gets called and it
> > might give a warning of non-zero ifs->r_b_p, because we updated
> > ifs->r_b_p during writes to a non-zero value, but the reads
> > never happend. Then during a call to ->release_folio, it will complain
> > of a non-zero ifs->r_b_p.
> 
> Yes, we'll have to remove that assertion.  I don't think that's a
> problem, do you?

Or refine it, as the parts not read shoud not be uptodate either?

Either way I had another idea to simplify things a bit, but this might
end up beeing even simpler, so I'll stop the hacking on my version
for now.