[libvirt] [PATCH] qemu: better error message when block job can't succeed

Michal Privoznik mprivozn at redhat.com
Wed Oct 29 04:28:54 UTC 2014


On 28.10.2014 15:31, Eric Blake wrote:
> https://bugzilla.redhat.com/show_bug.cgi?id=1140981 reports that
> the qemu-kvm shipped as part of RHEL 7.0 intentionally cripples
> block jobs by removing the 'block-stream' QMP command, but that
> our probe for whether block jobs work was merely whether
> 'block-job-cancel' exists.  Meanwhile, older qemu spelled the
> two commands block_stream and block_job_cancel.  We know of no
> qemu build that has block-stream while lacking block-job-cancel,
> so it is easiest to change our witness to the command that
> starts a job rather than ends one.  On RHEL, this results in
> changing the message from an ugly:
>
>   error: Requested operation is not valid: Command 'block-stream' is not found
>
> to a nicer:
>
>   error: unsupported configuration: block jobs not supported with this qemu binary
>
> * src/qemu/qemu_capabilities.h (QEMU_CAPS_BLOCKJOB_SYNC): Tweak comment.
> * src/qemu/qemu_capabilities.c (virQEMUCapsCommands): Look for stream
> rather than cancel when determining the flavor of block jobs supported.
>
> Signed-off-by: Eric Blake <eblake at redhat.com>
> ---
>   src/qemu/qemu_capabilities.c | 4 ++--
>   src/qemu/qemu_capabilities.h | 4 ++--
>   2 files changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/src/qemu/qemu_capabilities.c b/src/qemu/qemu_capabilities.c
> index 6fcb5c7..b6c0f1b 100644
> --- a/src/qemu/qemu_capabilities.c
> +++ b/src/qemu/qemu_capabilities.c
> @@ -1422,8 +1422,8 @@ struct virQEMUCapsStringFlags {
>   struct virQEMUCapsStringFlags virQEMUCapsCommands[] = {
>       { "system_wakeup", QEMU_CAPS_WAKEUP },
>       { "transaction", QEMU_CAPS_TRANSACTION },
> -    { "block_job_cancel", QEMU_CAPS_BLOCKJOB_SYNC },
> -    { "block-job-cancel", QEMU_CAPS_BLOCKJOB_ASYNC },
> +    { "block_stream", QEMU_CAPS_BLOCKJOB_SYNC },
> +    { "block-stream", QEMU_CAPS_BLOCKJOB_ASYNC },
>       { "dump-guest-memory", QEMU_CAPS_DUMP_GUEST_MEMORY },
>       { "query-spice", QEMU_CAPS_SPICE },
>       { "query-kvm", QEMU_CAPS_KVM },
> diff --git a/src/qemu/qemu_capabilities.h b/src/qemu/qemu_capabilities.h
> index 0214f30..c0e2172 100644
> --- a/src/qemu/qemu_capabilities.h
> +++ b/src/qemu/qemu_capabilities.h
> @@ -127,8 +127,8 @@ typedef enum {
>       QEMU_CAPS_SCSI_DISK_CHANNEL  = 87, /* Is scsi-disk.channel available? */
>       QEMU_CAPS_SCSI_BLOCK         = 88, /* -device scsi-block */
>       QEMU_CAPS_TRANSACTION        = 89, /* transaction monitor command */
> -    QEMU_CAPS_BLOCKJOB_SYNC      = 90, /* RHEL 6.2 block_job_cancel */
> -    QEMU_CAPS_BLOCKJOB_ASYNC     = 91, /* qemu 1.1 block-job-cancel */
> +    QEMU_CAPS_BLOCKJOB_SYNC      = 90, /* old block_job_cancel, block_stream */
> +    QEMU_CAPS_BLOCKJOB_ASYNC     = 91, /* new block-job-cancel, block-stream */
>       QEMU_CAPS_SCSI_CD            = 92, /* -device scsi-cd */
>       QEMU_CAPS_IDE_CD             = 93, /* -device ide-cd */
>       QEMU_CAPS_NO_USER_CONFIG     = 94, /* -no-user-config */
>

ACK and safe for the freeze.

Michal




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