Re: [libvirt] [PATCH] storage: Ignore block devices that fail format detection
On 11/23/2015 09:13 AM, Ján Tomko wrote:
On Fri, Oct 30, 2015 at 11:13:21AM -0400, John Ferlan wrote:
> https://bugzilla.redhat.com/show_bug.cgi?id=1276198
>
> Prior to commit id '98322052' failure to saferead the block device would
> cause an error to be logged and the device to be skipped while attempting
> to discover/create a stable target path for a new LUN (NPIV).
>
> This was because virStorageBackendSCSIFindLUs ignored errors from
> processLU and virStorageBackendSCSINewLun.
>
> Ignoring the failure allowed a multipath device with an "active" and
> "ghost" to be present on the host with the "ghost" block device
being
> ignored. This patch will return a -2 to the caller indicating the desire
> to ignore the block device since it cannot be used directly rather than
> fail the pool startup.
>
> Additionally, it was found during some debugging that it was possible
> for the virStorageBackendDetectBlockVolFormatFD to not detect a format,
> which while not a probably - we probably should at least add some sort
> of warning message.
>
> Signed-off-by: John Ferlan <jferlan(a)redhat.com>
> ---
> src/storage/storage_backend.c | 4 ++++
> src/storage/storage_backend_scsi.c | 7 ++++++-
> 2 files changed, 10 insertions(+), 1 deletion(-)
>
> diff --git a/src/storage/storage_backend.c b/src/storage/storage_backend.c
> index a375fe0..2de606f 100644
> --- a/src/storage/storage_backend.c
> +++ b/src/storage/storage_backend.c
> @@ -1393,6 +1393,10 @@ virStorageBackendDetectBlockVolFormatFD(virStorageSourcePtr
target,
> }
> }
>
> + if (target->format == VIR_STORAGE_POOL_DISK_UNKNOWN)
> + VIR_WARN("cannot determine the target format for '%s'",
> + target->path);
> +
> return 0;
> }
>
This change is unrelated to the other one. Also, is this warning really
needed? I think leaving the format as 'unknown' is visible enough.
No not needed - I can remove it or change to VIR_DEBUG - it was
certainly useful when debugging.
> diff --git a/src/storage/storage_backend_scsi.c
b/src/storage/storage_backend_scsi.c
> index a593a2b..d60473d 100644
> --- a/src/storage/storage_backend_scsi.c
> +++ b/src/storage/storage_backend_scsi.c
> @@ -224,9 +224,14 @@ virStorageBackendSCSINewLun(virStoragePoolObjPtr pool,
> goto cleanup;
> }
>
> + /* Failing to process the format is not fatal - we'll just skip
> + * this volume.
> + */
> if (virStorageBackendUpdateVolInfo(vol, true,
> - VIR_STORAGE_VOL_OPEN_DEFAULT) < 0)
> + VIR_STORAGE_VOL_OPEN_DEFAULT) < 0) {
> + retval = -2;
> goto cleanup;
Adding the VIR_STORAGE_VOL_OPEN_NOERROR flag and propagating it down to
virStorageBackendDetectBlockVolFormatFD would be nicer.
So it's not an OPEN failure rather this a READ failure. The volume could
be opened and passing OPEN_NOERROR along in the "more general" is
probably not what should be done as that opens up a new classification
of errors that could get by.
I'll work on adding a similar read noerror setting
John
That way it can return -2 on EIO if the flag is present without spamming
the logs. The other functions called by virStorageBackendUpdateVolInfo
can also return -1 on a fatal error that way (although there do not seem
to be any functions that could fail with NOERROR at the moment).
Jan