On Tue, 23 Feb 2021, Ming Lei wrote:
> I'd suggest to add a helper(such as, blk_round_down_sectors()) to round_down each
> one.
Yes - Here I'm sending the updated patch.
> --
> Ming
From: Mikulas Patocka <mpatocka@xxxxxxxxxx>
We get I/O errors when we run md-raid1 on the top of dm-integrity on the
top of ramdisk.
device-mapper: integrity: Bio not aligned on 8 sectors: 0xff00, 0xff
device-mapper: integrity: Bio not aligned on 8 sectors: 0xff00, 0xff
device-mapper: integrity: Bio not aligned on 8 sectors: 0xffff, 0x1
device-mapper: integrity: Bio not aligned on 8 sectors: 0xffff, 0x1
device-mapper: integrity: Bio not aligned on 8 sectors: 0x8048, 0xff
device-mapper: integrity: Bio not aligned on 8 sectors: 0x8147, 0xff
device-mapper: integrity: Bio not aligned on 8 sectors: 0x8246, 0xff
device-mapper: integrity: Bio not aligned on 8 sectors: 0x8345, 0xbb
The ramdisk device has logical_block_size 512 and max_sectors 255. The
dm-integrity device uses logical_block_size 4096 and it doesn't affect the
"max_sectors" value - thus, it inherits 255 from the ramdisk. So, we have
a device with max_sectors not aligned on logical_block_size.
The md-raid device sees that the underlying leg has max_sectors 255 and it
will split the bios on 255-sector boundary, making the bios unaligned on
logical_block_size.
In order to fix the bug, we round down max_sectors to logical_block_size.
Signed-off-by: Mikulas Patocka <mpatocka@xxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
---
block/blk-settings.c | 12 ++++++++++++
1 file changed, 12 insertions(+)
Index: linux-2.6/block/blk-settings.c
===================================================================
--- linux-2.6.orig/block/blk-settings.c 2021-02-23 17:18:59.000000000 +0100
+++ linux-2.6/block/blk-settings.c 2021-02-23 17:23:58.000000000 +0100
@@ -481,6 +481,14 @@ void blk_queue_io_opt(struct request_que
}
EXPORT_SYMBOL(blk_queue_io_opt);
+static unsigned int blk_round_down_sectors(unsigned int sectors, unsigned int lbs)
+{
+ sectors = round_down(sectors, lbs >> SECTOR_SHIFT);
+ if (sectors < PAGE_SIZE >> SECTOR_SHIFT)
+ sectors = PAGE_SIZE >> SECTOR_SHIFT;
+ return sectors;
+}
+
/**
* blk_stack_limits - adjust queue_limits for stacked devices
* @t: the stacking driver limits (top device)
@@ -607,6 +615,10 @@ int blk_stack_limits(struct queue_limits
ret = -1;
}
+ t->max_sectors = blk_round_down_sectors(t->max_sectors, t->logical_block_size);
+ t->max_hw_sectors = blk_round_down_sectors(t->max_hw_sectors, t->logical_block_size);
+ t->max_dev_sectors = blk_round_down_sectors(t->max_dev_sectors, t->logical_block_size);
+
/* Discard alignment and granularity */
if (b->discard_granularity) {
alignment = queue_limit_discard_alignment(b, start);
