On Tue, Apr 24, 2012 at 7:35 PM, Luiz Capitulino <lcapitul...@redhat.com> wrote:
> On Tue, 24 Apr 2012 14:53:55 +0100
> Stefan Hajnoczi <stefa...@linux.vnet.ibm.com> wrote:
>
>> The block job API uses -errno return values internally and we convert
>> these to Error in the QMP functions. This is ugly because the Error
>> should be created at the point where we still have all the relevant
>> information. More importantly, it is hard to add new error cases to
>> this case since we quickly run out of -errno values without losing
>> information.
>>
>> Go ahead an use Error directly and don't convert later.
>>
>> Signed-off-by: Stefan Hajnoczi <stefa...@linux.vnet.ibm.com>
>> ---
>> block.c | 4 +++-
>> block/stream.c | 11 +++++------
>> block_int.h | 11 +++++++----
>> blockdev.c | 16 +++++-----------
>> 4 files changed, 20 insertions(+), 22 deletions(-)
>>
>> diff --git a/block.c b/block.c
>> index fe74ddd..2b72a0f 100644
>> --- a/block.c
>> +++ b/block.c
>> @@ -4083,11 +4083,13 @@ out:
>> }
>>
>> void *block_job_create(const BlockJobType *job_type, BlockDriverState *bs,
>> - BlockDriverCompletionFunc *cb, void *opaque)
>> + BlockDriverCompletionFunc *cb, void *opaque,
>> + Error **errp)
>> {
>> BlockJob *job;
>>
>> if (bs->job || bdrv_in_use(bs)) {
>> + error_set(errp, QERR_DEVICE_IN_USE, bdrv_get_device_name(bs));
>> return NULL;
>> }
>> bdrv_set_in_use(bs, 1);
>> diff --git a/block/stream.c b/block/stream.c
>> index 0efe1ad..7002dc8 100644
>> --- a/block/stream.c
>> +++ b/block/stream.c
>> @@ -280,16 +280,16 @@ static BlockJobType stream_job_type = {
>> .set_speed = stream_set_speed,
>> };
>>
>> -int stream_start(BlockDriverState *bs, BlockDriverState *base,
>> - const char *base_id, BlockDriverCompletionFunc *cb,
>> - void *opaque)
>> +void stream_start(BlockDriverState *bs, BlockDriverState *base,
>> + const char *base_id, BlockDriverCompletionFunc *cb,
>> + void *opaque, Error **errp)
>> {
>> StreamBlockJob *s;
>> Coroutine *co;
>>
>> - s = block_job_create(&stream_job_type, bs, cb, opaque);
>> + s = block_job_create(&stream_job_type, bs, cb, opaque, errp);
>> if (!s) {
>> - return -EBUSY; /* bs must already be in use */
>> + return;
>> }
>>
>> s->base = base;
>> @@ -300,5 +300,4 @@ int stream_start(BlockDriverState *bs, BlockDriverState
>> *base,
>> co = qemu_coroutine_create(stream_run);
>> trace_stream_start(bs, base, s, co, opaque);
>> qemu_coroutine_enter(co, s);
>> - return 0;
>> }
>> diff --git a/block_int.h b/block_int.h
>> index 0acb49f..8cf6ce9 100644
>> --- a/block_int.h
>> +++ b/block_int.h
>> @@ -346,6 +346,7 @@ int is_windows_drive(const char *filename);
>> * @bs: The block
>> * @cb: Completion function for the job.
>> * @opaque: Opaque pointer value passed to @cb.
>> + * @errp: A location to return DeviceInUse.
>
> Quite minor, but this is not a good description. I'd say just "Error object".
I followed the style of the glib documentation for GError** arguments.
I'm happy to change to just "Error object".
>
>> *
>> * Create a new long-running block device job and return it. The job
>> * will call @cb asynchronously when the job completes. Note that
>> @@ -357,7 +358,8 @@ int is_windows_drive(const char *filename);
>> * called from a wrapper that is specific to the job type.
>> */
>> void *block_job_create(const BlockJobType *job_type, BlockDriverState *bs,
>> - BlockDriverCompletionFunc *cb, void *opaque);
>> + BlockDriverCompletionFunc *cb, void *opaque,
>> + Error **errp);
>>
>> /**
>> * block_job_complete:
>> @@ -417,6 +419,7 @@ void block_job_cancel_sync(BlockJob *job);
>> * backing file if the job completes. Ignored if @base is %NULL.
>> * @cb: Completion function for the job.
>> * @opaque: Opaque pointer value passed to @cb.
>> + * @errp: A location to return DeviceInUse.
>> *
>> * Start a streaming operation on @bs. Clusters that are unallocated
>> * in @bs, but allocated in any image between @base and @bs (both
>> @@ -424,8 +427,8 @@ void block_job_cancel_sync(BlockJob *job);
>> * streaming job, the backing file of @bs will be changed to
>> * @base_id in the written image and to @base in the live BlockDriverState.
>> */
>> -int stream_start(BlockDriverState *bs, BlockDriverState *base,
>> - const char *base_id, BlockDriverCompletionFunc *cb,
>> - void *opaque);
>> +void stream_start(BlockDriverState *bs, BlockDriverState *base,
>> + const char *base_id, BlockDriverCompletionFunc *cb,
>> + void *opaque, Error **errp);
>>
>> #endif /* BLOCK_INT_H */
>> diff --git a/blockdev.c b/blockdev.c
>> index 0c2440e..a411477 100644
>> --- a/blockdev.c
>> +++ b/blockdev.c
>> @@ -1095,7 +1095,7 @@ void qmp_block_stream(const char *device, bool
>> has_base,
>> {
>> BlockDriverState *bs;
>> BlockDriverState *base_bs = NULL;
>> - int ret;
>> + Error *local_err = NULL;
>>
>> bs = bdrv_find(device);
>> if (!bs) {
>> @@ -1111,16 +1111,10 @@ void qmp_block_stream(const char *device, bool
>> has_base,
>> }
>> }
>>
>> - ret = stream_start(bs, base_bs, base, block_stream_cb, bs);
>> - if (ret < 0) {
>> - switch (ret) {
>> - case -EBUSY:
>> - error_set(errp, QERR_DEVICE_IN_USE, device);
>> - return;
>> - default:
>> - error_set(errp, QERR_NOT_SUPPORTED);
>> - return;
>> - }
>
> Just to be sureI got this right, the default clause is not actually possible
> before this patch?
I checked, you are right. It was not used. By removing the -errno ->
Error conversion layer we ensure this kind of inconsistency cannot
happen.
Stefan
