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Date: Wed, 12 Mar 2025 06:21:55 +0100
From: Christoph Hellwig <hch@lst.de>
To: Luis Chamberlain <mcgrof@kernel.org>
Cc: liwang@redhat.com, brauner@kernel.org, hare@suse.de,
	willy@infradead.org, david@fromorbit.com, djwong@kernel.org,
	kbusch@kernel.org, john.g.garry@oracle.com, hch@lst.de,
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	p.raghav@samsung.com, da.gomez@samsung.com, kernel@pankajraghav.com
Subject: Re: [PATCH] block: add BLK_FEAT_LBS to check for PAGE_SIZE limit
Message-ID: <20250312052155.GA11864@lst.de>
References: <20250312050028.1784117-1-mcgrof@kernel.org>
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User-Agent: Mutt/1.5.17 (2007-11-01)

On Tue, Mar 11, 2025 at 10:00:28PM -0700, Luis Chamberlain wrote:
> We should take time to validate each block driver before enabling
> support for larger logical block sizes, so that those that didn't
> have support stay that way and don't need modifications.
> 
> Li Wang reported this as a regression on LTP via:
> 
> testcases/kernel/syscalls/ioctl/ioctl_loop06
> 
> Which uses the loopback driver to enable larger logical block sizes
> first with LOOP_CONFIGURE and then LOOP_SET_BLOCK_SIZE. While
> I see no reason why the loopback block driver can't support
> larger logical block sizes than PAGE_SIZE, leave this validation
> step as a secondary effort for each block driver.

This doesn't really make sense.  We don't want a flag that caps driver
controlled values at a arbitrary value (and then not used it at all in
the patch).

If you need extra per-driver validatation, do it in the driver.