Greetings;
Might I suggest using SECTOR_SIZE instead of 512? Or, perhaps, >> SECTOR_SHIFT instead of / 512. I don't understand the three conditionals. I believe max_sectors is supposed to be <= min(max_dev_sectors, max_hw_sectors), but I don't understand why max_sectors being small should adjust max_hw_sectors and max_dev_sectors. Are the conditions perhaps supposed to be different, adjusting each max_*sectors up to at least PAGE_SIZE / SECTOR_SIZE? Perhaps, like e.g. blk_queue_max_hw_sectors(), the conditionals should log if they are adjusting max_*sectors up to the minimum.
On Thu, Nov 19, 2020 at 3:37 PM Mikulas Patocka <mpatocka@xxxxxxxxxx> wrote:
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 <mpatocka@xxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
---
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)
+ 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)
+ t->max_dev_sectors = PAGE_SIZE / 512;
+
/* Discard alignment and granularity */
if (b->discard_granularity) {
alignment = queue_limit_discard_alignment(b, start);
--
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