block: keep a list of block jobs

The current way to obtain the list of existing block jobs is to
iterate over all root nodes and check which ones own a job.

Since we want to be able to support block jobs in other nodes as well,
this patch keeps a list of jobs that is updated every time one is
created or destroyed.

Signed-off-by: Alberto Garcia <berto@igalia.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>

blockjob.c

@@ -50,6 +50,16 @@ struct BlockJobTxn {
     int refcnt;
 };
 
+static QLIST_HEAD(, BlockJob) block_jobs = QLIST_HEAD_INITIALIZER(block_jobs);
+
+BlockJob *block_job_next(BlockJob *job)
+{
+    if (!job) {
+        return QLIST_FIRST(&block_jobs);
+    }
+    return QLIST_NEXT(job, job_list);
+}
+
 void *block_job_create(const BlockJobDriver *driver, BlockDriverState *bs,
                        int64_t speed, BlockCompletionFunc *cb,
                        void *opaque, Error **errp)
@@ -76,6 +86,8 @@ void *block_job_create(const BlockJobDriver *driver, BlockDriverState *bs,
     job->refcnt        = 1;
     bs->job = job;
 
+    QLIST_INSERT_HEAD(&block_jobs, job, job_list);
+
     /* Only set speed when necessary to avoid NotSupported error */
     if (speed != 0) {
         Error *local_err = NULL;
@@ -103,6 +115,7 @@ void block_job_unref(BlockJob *job)
         bdrv_unref(job->bs);
         error_free(job->blocker);
         g_free(job->id);
+        QLIST_REMOVE(job, job_list);
         g_free(job);
     }
 }

include/block/blockjob.h

@@ -135,6 +135,9 @@ struct BlockJob {
      */
     bool deferred_to_main_loop;
 
+    /** Element of the list of block jobs */
+    QLIST_ENTRY(BlockJob) job_list;
+
     /** Status that is published by the query-block-jobs QMP API */
     BlockDeviceIoStatus iostatus;
 
@@ -172,6 +175,17 @@ struct BlockJob {
     QLIST_ENTRY(BlockJob) txn_list;
 };
 
+/**
+ * block_job_next:
+ * @job: A block job, or %NULL.
+ *
+ * Get the next element from the list of block jobs after @job, or the
+ * first one if @job is %NULL.
+ *
+ * Returns the requested job, or %NULL if there are no more jobs left.
+ */
+BlockJob *block_job_next(BlockJob *job);
+
 /**
  * block_job_create:
  * @job_type: The class object for the newly-created job.