qcow2: Use coroutines
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
diff --git a/block/qcow2-cluster.c b/block/qcow2-cluster.c
index 882f50a..81cf77d 100644
--- a/block/qcow2-cluster.c
+++ b/block/qcow2-cluster.c
@@ -697,12 +697,12 @@
* m->depends_on is set to NULL and the other fields in m are meaningless.
*
* If the cluster is newly allocated, m->nb_clusters is set to the number of
- * contiguous clusters that have been allocated. This may be 0 if the request
- * conflict with another write request in flight; in this case, m->depends_on
- * is set and the remaining fields of m are meaningless.
+ * contiguous clusters that have been allocated. In this case, the other
+ * fields of m are valid and contain information about the first allocated
+ * cluster.
*
- * If m->nb_clusters is non-zero, the other fields of m are valid and contain
- * information about the first allocated cluster.
+ * If the request conflicts with another write request in flight, the coroutine
+ * is queued and will be reentered when the dependency has completed.
*
* Return 0 on success and -errno in error cases
*/
@@ -721,6 +721,7 @@
return ret;
}
+again:
nb_clusters = size_to_clusters(s, n_end << 9);
nb_clusters = MIN(nb_clusters, s->l2_size - l2_index);
@@ -792,12 +793,12 @@
}
if (nb_clusters == 0) {
- /* Set dependency and wait for a callback */
- m->depends_on = old_alloc;
- m->nb_clusters = 0;
- *num = 0;
-
- goto out_wait_dependency;
+ /* Wait for the dependency to complete. We need to recheck
+ * the free/allocated clusters when we continue. */
+ qemu_co_mutex_unlock(&s->lock);
+ qemu_co_queue_wait(&old_alloc->dependent_requests);
+ qemu_co_mutex_lock(&s->lock);
+ goto again;
}
}
}
@@ -834,9 +835,6 @@
return 0;
-out_wait_dependency:
- return qcow2_cache_put(bs, s->l2_table_cache, (void**) &l2_table);
-
fail:
qcow2_cache_put(bs, s->l2_table_cache, (void**) &l2_table);
fail_put:
