[Xen-devel] [PATCH] v2 - Add exclusive locking option to block-iscsi

[Steven Haigh <netwiz@xxxxxxxxx>]

On 2016-05-05 12:32, Steven Haigh wrote:
> Overview
>
> If you're using iSCSI, you can mount a target by multiple Dom0
> machines on the same target. For non-cluster aware filesystems, this
> can lead to disk corruption and general bad times by all. The iSCSI
> protocol allows the use of persistent reservations as per the SCSI
> disk spec. Low level SCSI commands for locking are handled by the
> sg_persist program (bundled with sg3_utils package in EL).
>
> The aim of this patch is to create a 'locktarget=y' option specified
> within the disk 'target' command for iSCSI to lock the target in
> exclusive mode on VM start with a key generated from the local systems
> IP, and release this lock on the shutdown of the DomU.
>
> Example Config:
> disk            =
> ['script=block-iscsi,vdev=xvda,target=iqn=iqn.1986-03.com.sun:02:mytarget,portal=iscsi.example.com,locktarget=y']
>
> In writing this, I have also re-factored parts of the script to put
> some things in what I believe to be a better place to make expansion
> easier. This is mainly in removing functions that purely call other
> functions with no actual code execution.
>
> Signed-off-by: Steven Haigh <netwiz@xxxxxxxxx>
>
> (on a side note, first time I've submitted a patch to the list and I'm
> currently stuck on a webmail client, so apologies in advance if this
> all goes wrong ;)
Changes in v2:
Bugfix: Call find_device to locate the /dev/sdX component of the iSCSI 
target before trying to run unlock_device().
Apologies for this oversight.

--
Steven Haigh

Email: netwiz@xxxxxxxxx
Web: https://www.crc.id.au
Phone: (03) 9001 6090 - 0412 935 897

Attachment: block-iscsi-locking-v2.patch
Description: Text Data

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