From: Christoph Hellwig <hch@infradead.org>
To: Brian Foster <bfoster@redhat.com>
Cc: "Darrick J. Wong" <djwong@kernel.org>,
linux-fsdevel@vger.kernel.org, linux-xfs@vger.kernel.org
Subject: Re: [PATCH 2/6] iomap, xfs: lift zero range hole mapping flush into xfs
Date: Fri, 7 Nov 2025 05:57:43 -0800 [thread overview]
Message-ID: <aQ3612r1qKFeM9Ur@infradead.org> (raw)
In-Reply-To: <aQzEQtynNsJLdLcD@bfoster>
On Thu, Nov 06, 2025 at 10:52:34AM -0500, Brian Foster wrote:
> > An unaligned pagecache write to an uncached region uses the read mapping
> > to pull data into the pagecache. For writeback, we'd use the write
> > mapping if it's non-null, or else the read mapping.
> >
>
> Or perhaps let the read/write mappings overlap? It's not clear to me if
> that's better or worse. ;P
It is much better for the case where they actually are different.
> > This might not move the needle much wrt to fixing your problem, but at
> > least it eliminates the weirdness around "@iomap is for reads except
> > when you're doing a write but you have to do a read *and* @srcmap isn't
> > a hole".
> >
>
> Yeah.. it might be reaching a pedantic level, but to me having a couple
> mappings that say "you can read from this range, write to that range,
> and they might be the same" is more clear than the srcmap/dstmap/maybe
> both logic we have today.
It is a lot better.
next prev parent reply other threads:[~2025-11-07 13:57 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-10-16 19:02 [PATCH 0/6] iomap, xfs: improve zero range flushing and lookup Brian Foster
2025-10-16 19:02 ` [PATCH 1/6] iomap: replace folio_batch allocation with stack allocation Brian Foster
2025-11-05 0:07 ` Darrick J. Wong
2025-11-05 15:27 ` Brian Foster
2025-11-05 21:41 ` Darrick J. Wong
2025-11-06 15:51 ` Brian Foster
2025-11-06 15:58 ` Darrick J. Wong
2025-10-16 19:02 ` [PATCH 2/6] iomap, xfs: lift zero range hole mapping flush into xfs Brian Foster
2025-11-05 0:31 ` Darrick J. Wong
2025-11-05 15:33 ` Brian Foster
2025-11-05 22:23 ` Darrick J. Wong
2025-11-06 15:52 ` Brian Foster
2025-11-06 23:32 ` Darrick J. Wong
2025-11-07 13:52 ` Brian Foster
2025-11-07 13:59 ` Christoph Hellwig
2025-11-07 13:57 ` Christoph Hellwig [this message]
2025-11-07 13:55 ` Christoph Hellwig
2025-10-16 19:03 ` [PATCH 3/6] xfs: flush eof folio before insert range size update Brian Foster
2025-11-05 0:14 ` Darrick J. Wong
2025-11-05 15:34 ` Brian Foster
2025-11-05 22:15 ` Darrick J. Wong
2025-10-16 19:03 ` [PATCH 4/6] xfs: look up cow fork extent earlier for buffered iomap_begin Brian Foster
2025-11-05 22:26 ` Darrick J. Wong
2025-10-16 19:03 ` [PATCH 5/6] xfs: only flush when COW fork blocks overlap data fork holes Brian Foster
2025-10-16 19:03 ` [PATCH 6/6] xfs: replace zero range flush with folio batch Brian Foster
2025-11-05 22:37 ` Darrick J. Wong
2025-11-06 15:53 ` Brian Foster
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