From: Jaegeuk Kim <jaegeuk@kernel.org> To: Eric Biggers <ebiggers@kernel.org> Cc: linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, linux-xfs@vger.kernel.org, linux-api@vger.kernel.org, linux-fscrypt@vger.kernel.org, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, Keith Busch <kbusch@kernel.org> Subject: Re: [PATCH v4 6/9] f2fs: don't allow DIO reads but not DIO writes Date: Sat, 30 Jul 2022 20:08:26 -0700 [thread overview] Message-ID: <YuXyKh8Zvr56rR4R@google.com> (raw) In-Reply-To: <Yt7dCcG0ns85QqJe@sol.localdomain> On 07/25, Eric Biggers wrote: > On Sat, Jul 23, 2022 at 07:01:59PM -0700, Jaegeuk Kim wrote: > > On 07/22, Eric Biggers wrote: > > > From: Eric Biggers <ebiggers@google.com> > > > > > > Currently, if an f2fs filesystem is mounted with the mode=lfs and > > > io_bits mount options, DIO reads are allowed but DIO writes are not. > > > Allowing DIO reads but not DIO writes is an unusual restriction, which > > > is likely to be surprising to applications, namely any application that > > > both reads and writes from a file (using O_DIRECT). This behavior is > > > also incompatible with the proposed STATX_DIOALIGN extension to statx. > > > Given this, let's drop the support for DIO reads in this configuration. > > > > IIRC, we allowed DIO reads since applications complained a lower performance. > > So, I'm afraid this change will make another confusion to users. Could > > you please apply the new bahavior only for STATX_DIOALIGN? > > > > Well, the issue is that the proposed STATX_DIOALIGN fields cannot represent this > weird case where DIO reads are allowed but not DIO writes. So the question is > whether this case actually matters, in which case we should make STATX_DIOALIGN > distinguish between DIO reads and DIO writes, or whether it's some odd edge case > that doesn't really matter, in which case we could just fix it or make > STATX_DIOALIGN report that DIO is unsupported. I was hoping that you had some > insight here. What sort of applications want DIO reads but not DIO writes? > Is this common at all? I think there's no specific application to use the LFS mode at this moment, but I'd like to allow DIO read for zoned device which will be used for Android devices. > > - Eric
WARNING: multiple messages have this Message-ID (diff)
From: Jaegeuk Kim <jaegeuk@kernel.org> To: Eric Biggers <ebiggers@kernel.org> Cc: linux-block@vger.kernel.org, linux-api@vger.kernel.org, linux-kernel@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, linux-xfs@vger.kernel.org, Keith Busch <kbusch@kernel.org>, linux-fscrypt@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org Subject: Re: [f2fs-dev] [PATCH v4 6/9] f2fs: don't allow DIO reads but not DIO writes Date: Sat, 30 Jul 2022 20:08:26 -0700 [thread overview] Message-ID: <YuXyKh8Zvr56rR4R@google.com> (raw) In-Reply-To: <Yt7dCcG0ns85QqJe@sol.localdomain> On 07/25, Eric Biggers wrote: > On Sat, Jul 23, 2022 at 07:01:59PM -0700, Jaegeuk Kim wrote: > > On 07/22, Eric Biggers wrote: > > > From: Eric Biggers <ebiggers@google.com> > > > > > > Currently, if an f2fs filesystem is mounted with the mode=lfs and > > > io_bits mount options, DIO reads are allowed but DIO writes are not. > > > Allowing DIO reads but not DIO writes is an unusual restriction, which > > > is likely to be surprising to applications, namely any application that > > > both reads and writes from a file (using O_DIRECT). This behavior is > > > also incompatible with the proposed STATX_DIOALIGN extension to statx. > > > Given this, let's drop the support for DIO reads in this configuration. > > > > IIRC, we allowed DIO reads since applications complained a lower performance. > > So, I'm afraid this change will make another confusion to users. Could > > you please apply the new bahavior only for STATX_DIOALIGN? > > > > Well, the issue is that the proposed STATX_DIOALIGN fields cannot represent this > weird case where DIO reads are allowed but not DIO writes. So the question is > whether this case actually matters, in which case we should make STATX_DIOALIGN > distinguish between DIO reads and DIO writes, or whether it's some odd edge case > that doesn't really matter, in which case we could just fix it or make > STATX_DIOALIGN report that DIO is unsupported. I was hoping that you had some > insight here. What sort of applications want DIO reads but not DIO writes? > Is this common at all? I think there's no specific application to use the LFS mode at this moment, but I'd like to allow DIO read for zoned device which will be used for Android devices. > > - Eric _______________________________________________ Linux-f2fs-devel mailing list Linux-f2fs-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel
next prev parent reply other threads:[~2022-07-31 3:08 UTC|newest] Thread overview: 61+ messages / expand[flat|nested] mbox.gz Atom feed top 2022-07-22 7:12 [PATCH v4 0/9] make statx() return DIO alignment information Eric Biggers 2022-07-22 7:12 ` [f2fs-dev] " Eric Biggers 2022-07-22 7:12 ` [PATCH v4 1/9] statx: add direct I/O " Eric Biggers 2022-07-22 7:12 ` [f2fs-dev] " Eric Biggers 2022-07-22 16:32 ` Darrick J. Wong 2022-07-22 16:32 ` [f2fs-dev] " Darrick J. Wong 2022-07-22 17:31 ` Martin K. Petersen 2022-07-22 17:31 ` [f2fs-dev] " Martin K. Petersen 2022-07-22 7:12 ` [PATCH v4 2/9] vfs: support STATX_DIOALIGN on block devices Eric Biggers 2022-07-22 7:12 ` [f2fs-dev] " Eric Biggers 2022-07-22 8:10 ` Christoph Hellwig 2022-07-22 8:10 ` [f2fs-dev] " Christoph Hellwig 2022-07-22 17:32 ` Martin K. Petersen 2022-07-22 17:32 ` [f2fs-dev] " Martin K. Petersen 2022-07-22 7:12 ` [PATCH v4 3/9] fscrypt: change fscrypt_dio_supported() to prepare for STATX_DIOALIGN Eric Biggers 2022-07-22 7:12 ` [f2fs-dev] " Eric Biggers 2022-07-22 8:10 ` Christoph Hellwig 2022-07-22 8:10 ` [f2fs-dev] " Christoph Hellwig 2022-07-22 7:12 ` [PATCH v4 4/9] ext4: support STATX_DIOALIGN Eric Biggers 2022-07-22 7:12 ` [f2fs-dev] " Eric Biggers 2022-07-22 17:05 ` Theodore Ts'o 2022-07-22 17:05 ` [f2fs-dev] " Theodore Ts'o 2022-07-22 7:12 ` [PATCH v4 5/9] f2fs: move f2fs_force_buffered_io() into file.c Eric Biggers 2022-07-22 7:12 ` [f2fs-dev] " Eric Biggers 2022-07-22 7:12 ` [PATCH v4 6/9] f2fs: don't allow DIO reads but not DIO writes Eric Biggers 2022-07-22 7:12 ` [f2fs-dev] " Eric Biggers 2022-07-24 2:01 ` Jaegeuk Kim 2022-07-24 2:01 ` [f2fs-dev] " Jaegeuk Kim 2022-07-25 18:12 ` Eric Biggers 2022-07-25 18:12 ` [f2fs-dev] " Eric Biggers 2022-07-25 23:58 ` Andreas Dilger 2022-07-31 3:08 ` Jaegeuk Kim [this message] 2022-07-31 3:08 ` [f2fs-dev] " Jaegeuk Kim 2022-08-16 0:55 ` Eric Biggers 2022-08-16 0:55 ` Eric Biggers 2022-08-16 9:03 ` [f2fs-dev] " Dave Chinner 2022-08-16 9:03 ` Dave Chinner 2022-08-16 16:42 ` Andreas Dilger 2022-08-19 23:09 ` Eric Biggers 2022-08-19 23:09 ` [f2fs-dev] " Eric Biggers 2022-08-23 3:22 ` Andreas Dilger 2022-08-20 0:06 ` Jaegeuk Kim 2022-08-20 0:06 ` [f2fs-dev] " Jaegeuk Kim 2022-08-20 0:33 ` Eric Biggers 2022-08-20 0:33 ` Eric Biggers 2022-08-21 8:53 ` Christoph Hellwig 2022-08-21 8:53 ` [f2fs-dev] " Christoph Hellwig 2022-07-22 7:12 ` [PATCH v4 7/9] f2fs: simplify f2fs_force_buffered_io() Eric Biggers 2022-07-22 7:12 ` [f2fs-dev] " Eric Biggers 2022-07-22 7:12 ` [PATCH v4 8/9] f2fs: support STATX_DIOALIGN Eric Biggers 2022-07-22 7:12 ` [f2fs-dev] " Eric Biggers 2022-07-22 7:12 ` [PATCH v4 9/9] xfs: " Eric Biggers 2022-07-22 7:12 ` [f2fs-dev] " Eric Biggers 2022-07-22 8:11 ` Christoph Hellwig 2022-07-22 8:11 ` [f2fs-dev] " Christoph Hellwig 2022-07-22 16:24 ` Darrick J. Wong 2022-07-22 16:24 ` [f2fs-dev] " Darrick J. Wong 2022-08-26 17:19 ` [PATCH v4 0/9] make statx() return DIO alignment information Jeff Layton 2022-08-26 17:19 ` [f2fs-dev] " Jeff Layton 2022-08-27 7:07 ` Eric Biggers 2022-08-27 7:07 ` [f2fs-dev] " Eric Biggers
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