Commit e74d93e9 authored Feb 28, 2020 by Konstantin Khlebnikov Committed by Song Liu Mar 17, 2020

block: keep bdi->io_pages in sync with max_sectors_kb for stacked devices

Field bdi->io_pages added in commit 9491ae4a ("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 set
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 c6d6e9b0 ("dm: do not allow readahead to limit IO size") fixed
the same problem for device-mapper devices, this one fixes MD RAIDs.

Fixes: 9491ae4a ("mm: don't cap request size based on read-ahead setting")
Reviewed-by: Paul Menzel <pmenzel@molgen.mpg.de>
Reviewed-by: Bob Liu <bob.liu@oracle.com>
Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Signed-off-by: Song Liu <songliubraving@fb.com>

parent 6b40bec3

block/blk-settings.c

+3 −0

Original line number	Diff line number	Diff line
		@@ -664,6 +664,9 @@ 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);

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