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From: Eric Biggers <ebiggers@kernel.org>
To: Stefan Hajnoczi <stefanha@redhat.com>
Cc: qemu-devel@nongnu.org, hreitz@redhat.com, qemu-block@nongnu.org,
	Kevin Wolf <kwolf@redhat.com>,
	nsoffer@redhat.com
Subject: Re: [PATCH 1/2] file-posix: fix Linux alignment probing when EIO is returned
Date: Tue, 1 Nov 2022 19:27:14 -0700	[thread overview]
Message-ID: <Y2HVgnwAPdTIaZR6@sol.localdomain> (raw)
In-Reply-To: <20221101190031.6766-2-stefanha@redhat.com>

On Tue, Nov 01, 2022 at 03:00:30PM -0400, Stefan Hajnoczi wrote:
> Linux dm-crypt returns errno EIO from unaligned O_DIRECT pread(2) calls.

Citation needed.  For direct I/O to block devices, the kernel's block layer
checks the alignment before the I/O is actually submitted to the underlying
block device.  See
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/block/fops.c?h=v6.1-rc3#n306

> Buglink: https://gitlab.com/qemu-project/qemu/-/issues/1290

That "bug" seems to be based on a misunderstanding of the kernel source code,
and not any actual testing.

I just tested it, and the error code is EINVAL.

- Eric


  reply	other threads:[~2022-11-02  2:27 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-11-01 19:00 [PATCH 0/2] file-posix: alignment probing improvements Stefan Hajnoczi
2022-11-01 19:00 ` [PATCH 1/2] file-posix: fix Linux alignment probing when EIO is returned Stefan Hajnoczi
2022-11-02  2:27   ` Eric Biggers [this message]
2022-11-02  2:49     ` Eric Biggers
2022-11-02 18:50       ` Stefan Hajnoczi
2022-11-03  9:52       ` Kevin Wolf
2022-11-03 13:57         ` Stefan Hajnoczi
2022-11-03 16:26         ` Eric Biggers
2022-11-03 16:54           ` Eric Biggers
2022-11-03 17:54             ` Stefan Hajnoczi
2022-11-01 19:00 ` [PATCH 2/2] file-posix: add statx(STATX_DIOALIGN) support Stefan Hajnoczi
2022-11-02  3:32   ` Eric Biggers
2022-11-02 18:53     ` Stefan Hajnoczi

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