Re: [PATCH AUTOSEL 6.11 14/76] iomap: fix iomap_dio_zero() for fs bs > system page size

[Dave Chinner]

On Fri, Oct 04, 2024 at 02:16:31PM -0400, Sasha Levin wrote:
> From: Pankaj Raghav <p.raghav@xxxxxxxxxxx>
> 
> [ 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@xxxxxxxxxxx>
> Link: https://lore.kernel.org/r/20240822135018.1931258-7-kernel@xxxxxxxxxxxxxxxx
> Reviewed-by: Hannes Reinecke <hare@xxxxxxx>
> Reviewed-by: Darrick J. Wong <djwong@xxxxxxxxxx>
> Reviewed-by: Dave Chinner <dchinner@xxxxxxxxxx>
> Reviewed-by: Daniel Gomez <da.gomez@xxxxxxxxxxx>
> Signed-off-by: Christian Brauner <brauner@xxxxxxxxxx>
> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
> ---
>  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@xxxxxxxxxxxxx