On Mon, Mar 2, 2020 at 4:16 AM Bob Liu <bob.liu@xxxxxxxxxx> wrote:
>
> 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>
Thanks for the fix. I fixed it based on the comments and applied it to md-next.
Jens, I picked the patch to md-next because md is the only user of
disk_stack_limits().
Please let me know if you prefer routing it via the block tree.
Thanks,
Song
