From: Mateusz Kusiak <mateusz.kusiak@linux.intel.com>
To: DM-devel-linux <dm-devel@lists.linux.dev>
Cc: linux-raid@vger.kernel.org
Subject: regression: mdadm detects dm-device as partition
Date: Thu, 21 Mar 2024 10:17:12 +0100 [thread overview]
Message-ID: <35e0eae0-7fb0-4029-8445-997e22c21482@linux.intel.com> (raw)
Hello,
We discovered an issue when trying to create imsm container with mdadm on dm-device.
The scenario is as follows:
1. Create dm device
# echo -e '0 195312 linear /dev/nvme2n1 0' | dmsetup create nvme2n1DM
2. Create IMSM container.
# dmdev=$(readlink -f /dev/mapper/nvme2n1DM)
# export IMSM_DEVNAME_AS_SERIAL=1 IMSM_NO_PLATFORM=1; mdadm --create /dev/md/container
--metadata=imsm --raid-disks=1 $dmdev --force
Result:
Error message is displayed
# mdadm: imsm: /dev/dm-0 is a partition, cannot be used in IMSM
Mdadm's function for checking "if partition" looks like so.
int test_partition(int fd)
{
/* Check if fd is a whole-disk or a partition.
* BLKPG will return EINVAL on a partition, and BLKPG_DEL_PARTITION
* will return ENXIO on an invalid partition number.
*/
struct blkpg_ioctl_arg a;
struct blkpg_partition p;
a.op = BLKPG_DEL_PARTITION;
a.data = (void*)&p;
a.datalen = sizeof(p);
a.flags = 0;
memset(a.data, 0, a.datalen);
p.pno = 1<<30;
if (ioctl(fd, BLKPG, &a) == 0)
/* Very unlikely, but not a partition */
return 0;
if (errno == ENXIO || errno == ENOTTY)
/* not a partition */
return 0;
return 1;
}
I plugged in with debugger and established that when ioctl is run on dm-device errno is EINVAL, as
if it was a partition.
The issue is reproducible only with newer kernels which leads me te believe there is a regression in
device mapper. This code has been working stable for last 10+ years, which is another reason. I
tested this on RHEL 8.9 with inbox 5.14 kernel and 6.5.7-1 I happen to have installed. The issue
reproduced only on 6.5.7-1 kernel. I also observed same regression on stock Ubuntu 24.04 with inbox
6.6.0 kernel.
Can you please point me to when it was introduced and are there any plans for fixing it?
Thanks,
Mateusz
next reply other threads:[~2024-03-21 9:17 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-03-21 9:17 Mateusz Kusiak [this message]
2024-03-25 2:41 ` regression: mdadm detects dm-device as partition Yu Kuai
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