Re: [PATCH v7 0/6] block/md/dm: set chunk_sectors from stacked dev stripe size

[John Garry <john.g.garry@oracle.com>]

On 11/07/2025 11:52, John Garry wrote:

Hi Jens,

Can you please consider picking up these changes on the block tree? They 
fix real issues which we encountered.

Thanks,
John

> This value in io_min is used to configure any atomic write limit for the
> stacked device. The idea is that the atomic write unit max is a
> power-of-2 factor of the stripe size, and the stripe size is available
> in io_min.
> 
> Using io_min causes issues, as:
> a. it may be mutated
> b. the check for io_min being set for determining if we are dealing with
> a striped device is hard to get right, as reported in [0].
> 
> This series now sets chunk_sectors limit to share stripe size.
> 
> [0] https://lore.kernel.org/linux-block/888f3b1d-7817-4007-b3b3-1a2ea04df771@linux.ibm.com/T/#mecca17129f72811137d3c2f1e477634e77f06781
> 
> Based on 8b428f42f3edf nbd: fix lockdep deadlock warning
> 
> This series fixes issues for v6.16, but it's prob better to have this in
> v6.17 .
> 
> Difference to v6:
> - do comparison in sectors in 2/6
> 
> Differences to v5:
> - Neaten code in blk_validate_atomic_write_limits() (Jens)
> 
> Differences to v4:
> - Use check_shl_overflow() (Nilay)
> - Use long long in for chunk bytes in 2/6
> - Add tags from Nilay (thanks!)
> 
> John Garry (6):
>    ilog2: add max_pow_of_two_factor()
>    block: sanitize chunk_sectors for atomic write limits
>    md/raid0: set chunk_sectors limit
>    md/raid10: set chunk_sectors limit
>    dm-stripe: limit chunk_sectors to the stripe size
>    block: use chunk_sectors when evaluating stacked atomic write limits
> 
>   block/blk-settings.c   | 62 ++++++++++++++++++++++++++----------------
>   drivers/md/dm-stripe.c |  1 +
>   drivers/md/raid0.c     |  1 +
>   drivers/md/raid10.c    |  1 +
>   fs/xfs/xfs_mount.c     |  5 ----
>   include/linux/log2.h   | 14 ++++++++++
>   6 files changed, 56 insertions(+), 28 deletions(-)
>