linux-kernel - Re: [PATCH AUTOSEL 6.11 14/76] iomap: fix iomap_dio

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Message-ID: <ZwBwRqGRwoDd2eT4@dread.disaster.area>
Date: Sat, 5 Oct 2024 08:46:30 +1000
From: Dave Chinner <david@...morbit.com>
To: Sasha Levin <sashal@...nel.org>
Cc: linux-kernel@...r.kernel.org, stable@...r.kernel.org,
	Pankaj Raghav <p.raghav@...sung.com>,
	Hannes Reinecke <hare@...e.de>,
	"Darrick J . Wong" <djwong@...nel.org>,
	Dave Chinner <dchinner@...hat.com>,
	Daniel Gomez <da.gomez@...sung.com>,
	Christian Brauner <brauner@...nel.org>, linux-xfs@...r.kernel.org,
	linux-fsdevel@...r.kernel.org
Subject: Re: [PATCH AUTOSEL 6.11 14/76] iomap: fix iomap_dio_zero() for fs bs
 > system page size

On Fri, Oct 04, 2024 at 02:16:31PM -0400, Sasha Levin wrote:
> From: Pankaj Raghav <p.raghav@...sung.com>
> 
> [ Upstream commit 10553a91652d995274da63fc317470f703765081 ]
> 
> iomap_dio_zero() will pad a fs block with zeroes if the direct IO size
> < fs block size. iomap_dio_zero() has an implicit assumption that fs block
> size < page_size. This is true for most filesystems at the moment.
> 
> If the block size > page size, this will send the contents of the page
> next to zero page(as len > PAGE_SIZE) to the underlying block device,
> causing FS corruption.
> 
> iomap is a generic infrastructure and it should not make any assumptions
> about the fs block size and the page size of the system.
> 
> Signed-off-by: Pankaj Raghav <p.raghav@...sung.com>
> Link: https://lore.kernel.org/r/20240822135018.1931258-7-kernel@pankajraghav.com
> Reviewed-by: Hannes Reinecke <hare@...e.de>
> Reviewed-by: Darrick J. Wong <djwong@...nel.org>
> Reviewed-by: Dave Chinner <dchinner@...hat.com>
> Reviewed-by: Daniel Gomez <da.gomez@...sung.com>
> Signed-off-by: Christian Brauner <brauner@...nel.org>
> Signed-off-by: Sasha Levin <sashal@...nel.org>
> ---
>  fs/iomap/buffered-io.c |  4 ++--
>  fs/iomap/direct-io.c   | 45 ++++++++++++++++++++++++++++++++++++------
>  2 files changed, 41 insertions(+), 8 deletions(-)

For the second time: NACK to this patch for -all- LTS kernels.

It is a support patch for a new feature introduced in 6.12-rc1 - it
is *not* a bug fix, it is not in any way relevant to LTS kernels,
and it will *break some architectures* as it stands.

-Dave.
-- 
Dave Chinner
david@...morbit.com