---------- Forwarded message ----------
Date: Thu, 19 Nov 2020 15:36:51 -0500 (EST)
From: Mikulas Patocka <mpatocka@xxxxxxxxxx>
To: David Teigland <teigland@xxxxxxxxxx>, Jens Axboe <axboe@xxxxxxxxx>
Cc: heinzm@xxxxxxxxxx, Zdenek Kabelac <zkabelac@xxxxxxxxxx>,
Marian Csontos <mcsontos@xxxxxxxxxx>, linux-block@xxxxxxxxxxxxxxx,
dm-devel@xxxxxxxxxx
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 <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);
