From: Christoph Hellwig <hch@lst.de>
To: Qu Wenruo <wqu@suse.com>
Cc: Christoph Hellwig <hch@lst.de>,
"Darrick J. Wong" <djwong@kernel.org>,
Carlos Maiolino <cem@kernel.org>,
Christian Brauner <brauner@kernel.org>, Jan Kara <jack@suse.cz>,
"Martin K. Petersen" <martin.petersen@oracle.com>,
linux-kernel@vger.kernel.org, linux-xfs@vger.kernel.org,
linux-fsdevel@vger.kernel.org, linux-raid@vger.kernel.org,
linux-block@vger.kernel.org, linux-btrfs@vger.kernel.org
Subject: Re: [PATCH 4/4] xfs: fallback to buffered I/O for direct I/O when stable writes are required
Date: Thu, 30 Oct 2025 08:17:04 +0100 [thread overview]
Message-ID: <20251030071704.GA14027@lst.de> (raw)
In-Reply-To: <c3512f2a-f995-4642-8eb9-a227890ba856@suse.com>
On Thu, Oct 30, 2025 at 05:44:22PM +1030, Qu Wenruo wrote:
> Because for whatever reasons, although the only reason I can come up with
> is performance.
>
> I thought the old kernel principle is, providing the mechanism not the
> policy.
> But the fallback-to-buffered looks more like a policy, and if that's the
> case user space should be more suitable.
I don't think so. O_DIRECT really is a hint. We already do fallbacks
for various reasons (for XFS e.g. unaligned writes on COW files), and
btrfs in fact falls back for any alignment mismatch already. And there's
really nothing an application can do when the most optimal way is not
available except for using a less optimal one. So there's really no
value add for an option to fail.
next prev parent reply other threads:[~2025-10-30 7:17 UTC|newest]
Thread overview: 54+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-10-29 7:15 fall back from direct to buffered I/O when stable writes are required Christoph Hellwig
2025-10-29 7:15 ` [PATCH 1/4] fs: replace FOP_DIO_PARALLEL_WRITE with a fmode bits Christoph Hellwig
2025-10-29 16:01 ` Darrick J. Wong
2025-11-04 7:00 ` Nirjhar Roy (IBM)
2025-11-05 14:04 ` Christoph Hellwig
2025-11-11 9:44 ` Christian Brauner
2025-10-29 7:15 ` [PATCH 2/4] fs: return writeback errors for IOCB_DONTCACHE in generic_write_sync Christoph Hellwig
2025-10-29 16:01 ` Darrick J. Wong
2025-10-29 16:37 ` Christoph Hellwig
2025-10-29 18:12 ` Darrick J. Wong
2025-10-30 5:59 ` Christoph Hellwig
2025-11-04 12:04 ` Nirjhar Roy (IBM)
2025-11-04 15:53 ` Christoph Hellwig
2025-10-29 7:15 ` [PATCH 3/4] xfs: use IOCB_DONTCACHE when falling back to buffered writes Christoph Hellwig
2025-10-29 15:57 ` Darrick J. Wong
2025-11-04 12:33 ` Nirjhar Roy (IBM)
2025-11-04 15:52 ` Christoph Hellwig
2025-10-29 7:15 ` [PATCH 4/4] xfs: fallback to buffered I/O for direct I/O when stable writes are required Christoph Hellwig
2025-10-29 15:53 ` Darrick J. Wong
2025-10-29 16:35 ` Christoph Hellwig
2025-10-29 21:23 ` Qu Wenruo
2025-10-30 5:58 ` Christoph Hellwig
2025-10-30 6:37 ` Qu Wenruo
2025-10-30 6:49 ` Christoph Hellwig
2025-10-30 6:53 ` Qu Wenruo
2025-10-30 6:55 ` Christoph Hellwig
2025-10-30 7:14 ` Qu Wenruo
2025-10-30 7:17 ` Christoph Hellwig [this message]
2025-11-10 13:38 ` Nirjhar Roy (IBM)
2025-11-10 13:59 ` Christoph Hellwig
2025-11-12 7:13 ` Nirjhar Roy (IBM)
2025-10-29 15:58 ` fall back from direct to buffered " Bart Van Assche
2025-10-29 16:14 ` Darrick J. Wong
2025-10-29 16:33 ` Christoph Hellwig
2025-10-30 11:20 ` Dave Chinner
2025-10-30 12:00 ` Geoff Back
2025-10-30 12:54 ` Jan Kara
2025-10-30 14:35 ` Christoph Hellwig
2025-10-30 22:02 ` Dave Chinner
2025-10-30 14:33 ` Christoph Hellwig
2025-10-30 23:18 ` Dave Chinner
2025-10-31 13:00 ` Christoph Hellwig
2025-10-31 15:57 ` Keith Busch
2025-10-31 16:47 ` Christoph Hellwig
2025-11-03 11:14 ` Jan Kara
2025-11-03 12:21 ` Christoph Hellwig
2025-11-03 22:47 ` Keith Busch
2025-11-04 23:38 ` Darrick J. Wong
2025-11-05 14:11 ` Christoph Hellwig
2025-11-05 21:44 ` Darrick J. Wong
2025-11-06 9:50 ` Johannes Thumshirn
2025-11-06 12:49 ` hch
2025-11-12 14:18 ` Ming Lei
2025-11-12 14:38 ` hch
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20251030071704.GA14027@lst.de \
--to=hch@lst.de \
--cc=brauner@kernel.org \
--cc=cem@kernel.org \
--cc=djwong@kernel.org \
--cc=jack@suse.cz \
--cc=linux-block@vger.kernel.org \
--cc=linux-btrfs@vger.kernel.org \
--cc=linux-fsdevel@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-raid@vger.kernel.org \
--cc=linux-xfs@vger.kernel.org \
--cc=martin.petersen@oracle.com \
--cc=wqu@suse.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).