Re: [libvirt] [PATCH 3/3] scsi: Check for invalid target.path after processLU failure
On 03/31/2015 07:57 AM, Ján Tomko wrote:
On Mon, Mar 30, 2015 at 07:16:34PM -0400, John Ferlan wrote:
> https://bugzilla.redhat.com/show_bug.cgi?id=1171933
>
> After processing all the LU's and find no "real" LU's - check if
perhaps
> the cause of that was a poorly formed 'target.path'. The expection is
> generally that the path is /dev/disk/by-path or at least something in /dev.
> Although it's not impossible for the user to provide something. If they
> do provide something it should be valid or we should just cause a failure
> to start the pool with an appropriate message.
>
> Signed-off-by: John Ferlan <jferlan(a)redhat.com>
> ---
> src/storage/storage_backend_scsi.c | 9 +++++++++
> 1 file changed, 9 insertions(+)
>
> diff --git a/src/storage/storage_backend_scsi.c b/src/storage/storage_backend_scsi.c
> index 2f1f5ed..c3a1892 100644
> --- a/src/storage/storage_backend_scsi.c
> +++ b/src/storage/storage_backend_scsi.c
> @@ -467,6 +467,15 @@ virStorageBackendSCSIFindLUsInternal(virStoragePoolObjPtr pool,
> if (!*found)
> VIR_DEBUG("No LU found for pool %s", pool->def->name);
>
> + if (!*found && !virFileExists(pool->def->target.path) &&
> + !STRPREFIX(pool->def->target.path, "/dev")) {
Checking for *found here seems pointless. After the logic change in the
previous patch, it is implied by either of the following conditions:
a) If the target path does not start with "/dev", *found will be false:
virStorageBackendStablePath will short-circuit, just strduping
the volume path, and virStorageBackendSCSINewLun will return -1
in that case.
b) If the target path does not exist, it will either be rejected by the
above code path, or by the failed opendir in
virStorageBackendStablePath.
If all you want to do is forbid to start an {,i}SCSI pool that does not
start with /dev, we can do that much earlier in {,I}SCSIStartPool.
The goal was to not start one that has a non-existent pool target.path,
but where/how that's determined is a little bit more involved than other
pools which could use virFileExists() on the pool's target.path in a
Check or Refresh and decide that it's not possible to start the pool.
For iscsi, that path creation is not "managed" by libvirt, hence the
wait loop in virStorageBackendStablePath.
I suppose I could check in start/check that if the target.path doesn't
start with /dev[/], then do a virFileExists on the provided path. If
that path doesn't exist, then fail the startup. That would "solve" the
bug without messing with processLU's return values.
To catch wrong paths in /dev, I think the proper way is to stop
ignoring
the return value of processLU and make it return -1 on fatal errors
(OOM, pool target path does not exist, etc.) and -2 on errors that won't
necessarily stop us from finding other volumes.
Having processLU return 1 had more to do with distinguishing the
difference between a non disk/lun and a finding a disk/lun. What I found
was for iSCSI "found = true" was being set because of the
/sys/bus/scsi/devices/<id>/type file had 0xC (or 12 or a controller)
(<id> is the host:bus:target:lun).
The concern over wrong paths or something that doesn't start with
/dev[/] and having it be a failure is there has to be a reason a non
/dev[/] path was allowed and if we return -1 just because of that I'm
unclear what effect that has since the code is shared between scsi and
iscsi... I do agree that other failures in virStorageBackendSCSINewLun
should be differentiated.
I've made some adjustments and will repost shortly
John