Bug 1328077

Summary:	multipath reports successful resize of math on second attempt
Product:	Red Hat Enterprise Linux 6	Reporter:	Lukas Herbolt <lherbolt>
Component:	device-mapper-multipath	Assignee:	Ben Marzinski <bmarzins>
Status:	CLOSED ERRATA	QA Contact:	Lin Li <lilin>
Severity:	high	Docs Contact:	Milan Navratil <mnavrati>
Priority:	high
Version:	6.7	CC:	agk, bmarzins, dwysocha, heinzm, lherbolt, lilin, loberman, msnitzer, prajnoha, prockai, rbalakri, yizhan, zkabelac
Target Milestone:	rc
Target Release:	---
Hardware:	x86_64
OS:	Linux
Whiteboard:
Fixed In Version:	device-mapper-multipath-0.4.9-94.el6	Doc Type:	Bug Fix
Doc Text:	multipathd no longer reports success after a failed device resizing If the multipathd service failed to resize a device, multipathd did not reset the size back to the original value internally. As a consequence, on future attempts to resize a device, multipathd reported a success even when multipathd did not resize the device. If resizing fails, multipathd now reverts the size of the device back to the original value internally. As a result, multipathd now only reports success if a device is resized successfully.	Story Points:	---
Clone Of:
Clones:	1333492 (view as bug list)		Environment:
Last Closed:	2017-03-21 10:50:21 UTC	Type:	Bug
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:
Bug Depends On:
Bug Blocks:	1269194, 1324930, 1333492

Description Lukas Herbolt 2016-04-18 11:49:39 UTC

Description of problem:
Multipath reports path as sucessfully resized after second attempt despite of the size in DM table remains.

Version-Release number of selected component (if applicable):
 - device-mapper-multipath-0.4.9-87.el6.x86_64
 - device-mapper-libs-1.02.95-2.el6.x86_64
 - device-mapper-1.02.95-2.el6.x86_64

How reproducible:
Resizing of multipath device which is on top of two devices with different 
size results with fail on first attempt but success on second one.

Steps to Reproduce:
Running on VM where I use two devices grouped to multipath over serial.
Devices has different size first 100M second 200M
(I know this is ugly hack, but it is quick way how to reproduce it.)

1.
Create two device with different size and set same serial number over
qemu or libvirt (it works on latest F23 as hypervizor)

2.
Configure mpath to group by serial

3.
Manually over dmsetup create multipath target. It's important to have the bigger device as first!
# dmsetup create mpathe --table "0 204800 multipath 0 0 2 1 round-robin 0 1 1 8:144 1 round-robin 0 1 1 8:64 1"

4.
# multipathd -d resize map /dev/mapper/mpathe
fail

You will get in messages:
Apr 18 12:13:44 rhel6-debug kernel: [ 4913.905877] device-mapper: table: 253:2: sde too small for target: start=0, len=409600, dev_size=204800

5.
On second attempt:
# multipathd -d resize map /dev/mapper/mpathe
ok

And in logs you will have message like. 
Apr 18 12:13:47 rhel6-debug multipathd: mpathe: map is still the same size (409600)
Apr 18 12:13:48 rhel6-debug multipathd: mpathe: resize map (operator)

but the actual size is still the same:

# dmsetup table mpathe
0 204800 multipath 0 0 2 1 round-robin 0 1 1 8:144 1 round-robin 0 1 1 8:64 1 


Actual results:
The mpath is reported as sucesfully resized but the size is still the same.

Expected results:
It should report fail on every attempt. 


Additional info:
[3:0:4:0]    disk    QEMU     QEMU HARDDISK    2.4.  /dev/sde [8:64]
[4:0:4:0]    disk    QEMU     QEMU HARDDISK    2.4.  /dev/sdj [8:144]

[root@rhel6-debug ~]# sg_readcap /dev/sde 
Read Capacity results:
   Last logical block address=204799 (0x31fff), Number of blocks=204800
   Logical block length=512 bytes
Hence:
   Device size: 104857600 bytes, 100.0 MiB, 0.10 GB
[root@rhel6-debug ~]# sg_readcap /dev/sdj
Read Capacity results:
   Last logical block address=409599 (0x63fff), Number of blocks=409600
   Logical block length=512 bytes
Hence:
   Device size: 209715200 bytes, 200.0 MiB, 0.21 GB


--
Lukas

Comment 6 Ben Marzinski 2016-10-15 21:44:53 UTC

Fixed this. Multipathd was updating the device size internally, even on failures. So on future attempts, it thought the device was already the new size. Now it keeps the original size, until the resize actually succeeds.

Comment 16 errata-xmlrpc 2017-03-21 10:50:21 UTC

Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory, and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://rhn.redhat.com/errata/RHBA-2017-0697.html