[multipath-tools] kpartx -a: resume ioctl failed: Invalid argument

[multipath-tools] kpartx -a: resume ioctl failed: Invalid argument

[Petr Uzel]

Hi all,

I have a simple testing linear DM device:

dmsetup info
> Name:              test
> State:             ACTIVE
> Read Ahead:        256
> Tables present:    LIVE
> Open count:        0
> Event number:      0
> Major, minor:      253, 0
> Number of targets: 1

# Let's create a partition:
parted -s /dev/dm-0 mkpart primary ext2 0 10M

# Create devmapping with kpartx:
kpartx -v -a -p _part /dev/dm-0 
> add map test_part1 (253:1): 0 19531 linear /dev/dm-0 1

dmsetup info test_part1
> Name:              test_part1
> State:             ACTIVE
> Read Ahead:        256
> Tables present:    LIVE
> Open count:        0
> Event number:      0
> Major, minor:      253, 1
> Number of targets: 1
> UUID: part1-dm-0

# Recreate the partition with different size:
parted -s /dev/dm-0 rm 1
parted -s /dev/dm-0 mkpart primary ext2 0 20M

# Try to recreate devmappings with kpartx:
kpartx -v -a -p _part /dev/dm-0 
> device-mapper: resume ioctl failed: Invalid argument
> resume failed on test_part1
> add map test_part1 (253:1): 0 39062 linear /dev/dm-0 1

Note: the ioctl doesn't fail when kpartx is called multiple times without
changing the partition table on dm-0.

It happens with current multipath-tools from git. The bug is caused by
----
commit 44b1e84d7eb72a3c03cec486a227dc1beaa9ccd6
Author:     Hannes Reinecke <hare@suse.de>
AuthorDate: Mon Feb 9 13:59:57 2009 +0100
Commit:     Christophe Varoqui <christophe.varoqui@free.fr>
CommitDate: Wed Apr 22 01:44:53 2009 +0200

    Use noflush for kpartx

	kpartx has to use 'noflush' to be able to complete for an all-paths
	down scenario. Otherwise no uevent might be sent and multipath
	will stall.
----

The patch uses --noflush with DM_DEVICE_RESUME, but as far as I understand it,
--noflush makes sense only with DM_DEVICE_SUSPEND.

Perhaps kpartx should suspend the mapping before doing reload?


-- 
Best regards / s pozdravem

Petr Uzel, Packages maintainer
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