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From: "Arnd Bergmann" <arnd@arndb.de>
To: "Hungyu Lin" <dennylin0707@gmail.com>, "Jens Axboe" <axboe@kernel.dk>
Cc: ben.hutchings@codethink.co.uk, linux-block@vger.kernel.org,
	linux-kernel@vger.kernel.org, stable@vger.kernel.org
Subject: Re: [PATCH] block: Return the soft block size for compat BLKBSZGET
Date: Fri, 23 Oct 2026 18:27:07 +0200	[thread overview]
Message-ID: <0241d3be-82d3-4ad0-a055-3897e7dfc475@app.fastmail.com> (raw)
In-Reply-To: <20261023153645.37546-1-dennylin0707@gmail.com>

On Fri, Oct 23, 2026, at 17:36, Hungyu Lin wrote:
> BLKBSZGET returns the block device's soft block size, while BLKSSZGET
> returns its logical sector size. The compat BLKBSZGET_32 handler uses
> bdev_logical_block_size(), so it returns the wrong value when these
> sizes differ.
>
> For example, on an x86_64 kernel a native query of a RAM or loop device
> with 512-byte logical sectors returns the initial soft block size of
> 4096 bytes, but an i386 process gets 512 bytes. This makes 32-bit
> blockdev --getbsz and the BSZ column of --report disagree with native
> queries, even without a preceding BLKBSZSET.
>
> Use block_size() as the native handler and the pre-regression compat
> handler do, and correct the case comment to describe the soft size.
>
> Fixes: 9b81648cb5e3 ("compat_ioctl: simplify up block/ioctl.c")
> Cc: stable@vger.kernel.org
> Signed-off-by: Hungyu Lin <dennylin0707@gmail.com>

Reviewed-by: Arnd Bergmann <arnd@arndb.de>

      reply	other threads:[~2026-10-23 16:27 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-10-23 15:36 Hungyu Lin
2026-10-23 16:27 ` Arnd Bergmann [this message]

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