On Fri, Sep 07, 2018 at 12:43:09PM +0200, Roger Pau Monné wrote:
> I would prefer if you could avoid open-coding this here, and instead
> use xen_vbd_create or similar. I would also prefer that the call to
> xen_vbd_create in backend_changed was removed and we had a single call
> to xen_vbd_create that's used for both initial device connection and
> reconnection.
>
> Also, I think this could cause issues if for some reason the frontend
> switches to state 'Connected' before hotplug scripts have run, in
> which case you would try to open an unexpected device because pdevice
> won't be correctly set.
Sure, this is just to test if the idea would work and needs a lot of
cleanup. Unfortunately it does not seem to help with the original
problem because this case is not executed on VM shutdown:
case XenbusStateClosed:
xen_blkif_disconnect(be->blkif);
xen_vbd_free(&be->blkif->vbd);
xenbus_switch_state(dev, XenbusStateClosed);
Instead xen_vbd_free gets run from a different code path after the
remove script has already failed:
[ 337.407634] block drbd0: State change failed: Device is held open by someone
[ 337.407673] block drbd0: state = { cs:Connected ro:Primary/Secondary ds:UpToDate/UpToDate r----- }
[ 337.407713] block drbd0: wanted = { cs:Connected ro:Secondary/Secondary ds:UpToDate/UpToDate r----- }
...
[ 340.109459] Workqueue: events xen_blkif_deferred_free [xen_blkback]
[ 340.109461] 0000000000000000 ffffffff81331e54 ffff883f84d19d38 ffff883f84d19d32
[ 340.109463] ffffffffc058169e ffff883f84d19d88 ffff883f84d19d20 ffffffffc05816f7
[ 340.109465] ffff883f84d19d88 ffff883f87b5a900 ffffffff81092fea 0000000088ec3080
[ 340.109467] Call Trace:
[ 340.109471] [<ffffffff81331e54>] ? dump_stack+0x5c/0x78
[ 340.109473] [<ffffffffc058169e>] ? xen_vbd_free.isra.9+0x2e/0x60 [xen_blkback]
[ 340.109475] [<ffffffffc05816f7>] ? xen_blkif_deferred_free+0x27/0x70 [xen_blkback]
[ 340.109477] [<ffffffff81092fea>] ? process_one_work+0x18a/0x420
[ 340.109479] [<ffffffff810932cd>] ? worker_thread+0x4d/0x490
[ 340.109480] [<ffffffff81093280>] ? process_one_work+0x420/0x420
[ 340.109482] [<ffffffff81099329>] ? kthread+0xd9/0xf0
[ 340.109484] [<ffffffff81099250>] ? kthread_park+0x60/0x60
[ 340.109486] [<ffffffff81615df7>] ? ret_from_fork+0x57/0x70
--
Valentin
