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Date: Thu, 17 Apr 2025 08:25:27 +0200
From: Christoph Hellwig <hch@lst.de>
To: "Darrick J. Wong" <djwong@kernel.org>
Cc: Jens Axboe <axboe@kernel.dk>, Christoph Hellwig <hch@lst.de>,
	linux-block@vger.kernel.org, ming.lei@redhat.com,
	linux-fsdevel <linux-fsdevel@vger.kernel.org>
Subject: Re: [PATCH] loop: fix min directio size detection for nested loop
 devices
Message-ID: <20250417062527.GA22173@lst.de>
References: <20250417034639.GG25659@frogsfrogsfrogs>
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On Wed, Apr 16, 2025 at 08:46:39PM -0700, Darrick J. Wong wrote:
> If however SCRATCH_DEV is itself a loop device that we've used to
> simulate 4k LBA block devices, the minimum directio size discovery
> introduced in commit f4774e92aab85d is wrong -- we should query the
> logical block size of the underlying block device because file->f_path
> points whatever filesystem /dev is.

No, the problem is that special handling of block devices in stat
sits in vfs_statx_path and not the exported vfs_getattr helper,
and thus we don't call into bdev_statx which would return the right
value.  I'll send a separate VFS-level fix for this.