dm-raid: don't set io_min and io_opt for raid1

JIRA: https://issues.redhat.com/browse/RHEL-119009
Upstream Status: kernel/git/torvalds/linux.git

commit a865562
Author: Mikulas Patocka <mpatocka@redhat.com>
Date:   Mon Sep 15 16:12:40 2025 +0200

    dm-raid: don't set io_min and io_opt for raid1

    These commands
     modprobe brd rd_size=1048576
     vgcreate vg /dev/ram*
     lvcreate -m4 -L10 -n lv vg
    trigger the following warnings:
    device-mapper: table: 252:10: adding target device (start sect 0 len 24576) caused an alignment inconsistency
    device-mapper: table: 252:10: adding target device (start sect 0 len 24576) caused an alignment inconsistency

    The warnings are caused by the fact that io_min is 512 and physical block
    size is 4096.

    If there's chunk-less raid, such as raid1, io_min shouldn't be set to zero
    because it would be raised to 512 and it would trigger the warning.

    Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
    Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
    Cc: stable@vger.kernel.org

Signed-off-by: Benjamin Marzinski <bmarzins@redhat.com>

Author: bmarzins

drivers/md/dm-raid.c

@@ -3817,8 +3817,10 @@ static void raid_io_hints(struct dm_target *ti, struct queue_limits *limits)
 	struct raid_set *rs = ti->private;
 	unsigned int chunk_size_bytes = to_bytes(rs->md.chunk_sectors);
 
-	limits->io_min = chunk_size_bytes;
-	limits->io_opt = chunk_size_bytes * mddev_data_stripes(rs);
+	if (chunk_size_bytes) {
+		limits->io_min = chunk_size_bytes;
+		limits->io_opt = chunk_size_bytes * mddev_data_stripes(rs);
+	}
 }
 
 static void raid_presuspend(struct dm_target *ti)