On Mon, Feb 22, 2021 at 01:15:32PM -0500, Mikulas Patocka wrote:
>
>
> ---------- Forwarded message ----------
> Date: Thu, 19 Nov 2020 15:36:51 -0500 (EST)
> From: Mikulas Patocka <[email protected]>
> To: David Teigland <[email protected]>, Jens Axboe <[email protected]>
> Cc: [email protected], Zdenek Kabelac <[email protected]>,
> Marian Csontos <[email protected]>, [email protected],
> [email protected]
> Subject: [PATCH] blk-settings: make sure that max_sectors is aligned on
> "logical_block_size" boundary.
>
> We get these 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 <[email protected]>
> Cc: [email protected]
>
> ---
> block/blk-settings.c | 10 ++++++++++
> 1 file changed, 10 insertions(+)
>
> Index: linux-2.6/block/blk-settings.c
> ===================================================================
> --- linux-2.6.orig/block/blk-settings.c 2020-10-29 12:20:46.000000000
> +0100
> +++ linux-2.6/block/blk-settings.c 2020-11-19 21:20:18.000000000 +0100
> @@ -591,6 +591,16 @@ int blk_stack_limits(struct queue_limits
> ret = -1;
> }
>
> + t->max_sectors = round_down(t->max_sectors, t->logical_block_size /
> 512);
> + if (t->max_sectors < PAGE_SIZE / 512)
> + t->max_sectors = PAGE_SIZE / 512;
> + t->max_hw_sectors = round_down(t->max_hw_sectors, t->logical_block_size
> / 512);
> + if (t->max_sectors < PAGE_SIZE / 512)
if (t->max_hw_sectors < PAGE_SIZE / 512)
> + t->max_hw_sectors = PAGE_SIZE / 512;
> + t->max_dev_sectors = round_down(t->max_dev_sectors,
> t->logical_block_size / 512);
> + if (t->max_sectors < PAGE_SIZE / 512)
if (t->max_dev_sectors < PAGE_SIZE / 512)
> + t->max_dev_sectors = PAGE_SIZE / 512;
I'd suggest to add a helper(such as, blk_round_down_sectors()) to round_down
each
one.
--
Ming
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