block: use Error mechanism instead of -errno for block_job_create()

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 and use Error directly and don't convert later. Signed-off-by: Stefan Hajnoczi <[email protected]> Acked-by: Kevin Wolf <[email protected]> Signed-off-by: Luiz Capitulino <[email protected]>
dreddy · Apr 27, 2012 · fd7f8c6 · fd7f8c6
1 parent be5ea8e
commit fd7f8c6
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Showing 4 changed files with 20 additions and 22 deletions.
diff --git a/block.c b/block.c
@@ -4083,11 +4083,13 @@ int bdrv_img_create(const char *filename, const char *fmt,
 }
 
 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
@@ -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
@@ -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: 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:
@@ -417,15 +419,16 @@ 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: Error object.
  *
  * Start a streaming operation on @bs.  Clusters that are unallocated
  * in @bs, but allocated in any image between @base and @bs (both
  * exclusive) will be written to @bs.  At the end of a successful
  * 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
@@ -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;
-        }
+    stream_start(bs, base_bs, base, block_stream_cb, bs, &local_err);
+    if (error_is_set(&local_err)) {
+        error_propagate(errp, local_err);
+        return;
     }
 
     /* Grab a reference so hotplug does not delete the BlockDriverState from