On Fri, Sep 11, 2020 at 05:53:37PM -0400, Mike Snitzer wrote:
> Like 'io_opt', blk_stack_limits() should stack 'chunk_sectors' using
> lcm_not_zero() rather than min_not_zero() -- otherwise the final
> 'chunk_sectors' could result in sub-optimal alignment of IO to
> component devices in the IO stack.
>
> Also, if 'chunk_sectors' isn't a multiple of 'physical_block_size'
> then it is a bug in the driver and the device should be flagged as
> 'misaligned'.
>
> Signed-off-by: Mike Snitzer <snitzer@xxxxxxxxxx>
> ---
> block/blk-settings.c | 12 ++++++++----
> 1 file changed, 8 insertions(+), 4 deletions(-)
>
> diff --git a/block/blk-settings.c b/block/blk-settings.c
> index 76a7e03bcd6c..b09642d5f15e 100644
> --- a/block/blk-settings.c
> +++ b/block/blk-settings.c
> @@ -534,6 +534,7 @@ int blk_stack_limits(struct queue_limits *t, struct queue_limits *b,
>
> t->io_min = max(t->io_min, b->io_min);
> t->io_opt = lcm_not_zero(t->io_opt, b->io_opt);
> + t->chunk_sectors = lcm_not_zero(t->chunk_sectors, b->chunk_sectors);
>
> /* Physical block size a multiple of the logical block size? */
> if (t->physical_block_size & (t->logical_block_size - 1)) {
> @@ -556,6 +557,13 @@ int blk_stack_limits(struct queue_limits *t, struct queue_limits *b,
> ret = -1;
> }
>
> + /* chunk_sectors a multiple of the physical block size? */
> + if (t->chunk_sectors & (t->physical_block_size - 1)) {
> + t->chunk_sectors = 0;
> + t->misaligned = 1;
> + ret = -1;
> + }
> +
> t->raid_partial_stripes_expensive =
> max(t->raid_partial_stripes_expensive,
> b->raid_partial_stripes_expensive);
> @@ -594,10 +602,6 @@ int blk_stack_limits(struct queue_limits *t, struct queue_limits *b,
> t->discard_granularity;
> }
>
> - if (b->chunk_sectors)
> - t->chunk_sectors = min_not_zero(t->chunk_sectors,
> - b->chunk_sectors);
> -
> t->zoned = max(t->zoned, b->zoned);
> return ret;
> }
Looks fine:
Reviewed-by: Ming Lei <ming.lei@xxxxxxxxxx>
Thanks,
Ming
