On 2/28/20 10:51 PM, Konstantin Khlebnikov wrote:
> Field bdi->io_pages added in commit 9491ae4aade6 ("mm: don't cap request
> size based on read-ahead setting") removes unneeded split of read requests.
>
> Stacked drivers do not call blk_queue_max_hw_sectors(). Instead they setup
> limits of their devices by blk_set_stacking_limits() + disk_stack_limits().
> Field bio->io_pages stays zero until user set max_sectors_kb via sysfs.
>
> This patch updates io_pages after merging limits in disk_stack_limits().
>
> Commit c6d6e9b0f6b4 ("dm: do not allow readahead to limit IO size") fixed
> the same problem for device-mapper devices, this one fixes MD RAIDs.
>
> Signed-off-by: Konstantin Khlebnikov <khlebnikov@xxxxxxxxxxxxxx>
> ---
> block/blk-settings.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/block/blk-settings.c b/block/blk-settings.c
> index c8eda2e7b91e..66c45fd79545 100644
> --- a/block/blk-settings.c
> +++ b/block/blk-settings.c
> @@ -664,6 +664,8 @@ void disk_stack_limits(struct gendisk *disk, struct block_device *bdev,
> printk(KERN_NOTICE "%s: Warning: Device %s is misaligned\n",
> top, bottom);
> }
> +
> + t->backing_dev_info->io_pages = t->limits.max_sectors >> (PAGE_SHIFT-9);
> }
> EXPORT_SYMBOL(disk_stack_limits);
>
>
Nitpick.. (PAGE_SHIFT - 9)
Reviewed-by: Bob Liu <bob.liu@xxxxxxxxxx>
