[Qemu-devel] [PATCH v8 01/11] block: keep a list of block jobs

[Alberto Garcia]

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.

This also updates qmp_query_block_jobs() and bdrv_drain_all() to use
this new list.

Signed-off-by: Alberto Garcia <address@hidden>
Cc: Max Reitz <address@hidden>
Cc: Eric Blake <address@hidden>
Cc: Alexander Yarygin <address@hidden>
---
 block/io.c               | 22 +++++++++++-----------
 blockdev.c               | 19 ++++++++-----------
 blockjob.c               | 13 +++++++++++++
 include/block/blockjob.h | 14 ++++++++++++++
 4 files changed, 46 insertions(+), 22 deletions(-)

diff --git a/block/io.c b/block/io.c
index 4a7a969..2fb89f2 100644
--- a/block/io.c
+++ b/block/io.c
@@ -271,16 +271,19 @@ void bdrv_drain_all(void)
     /* Always run first iteration so any pending completion BHs run */
     bool busy = true;
     BlockDriverState *bs = NULL;
+    BlockJob *job = NULL;
     GSList *aio_ctxs = NULL, *ctx;
 
-    while ((bs = bdrv_next(bs))) {
-        AioContext *aio_context = bdrv_get_aio_context(bs);
+    while ((job = block_job_next(job))) {
+        AioContext *aio_context = bdrv_get_aio_context(job->bs);
 
         aio_context_acquire(aio_context);
-        if (bs->job) {
-            block_job_pause(bs->job);
-        }
+        block_job_pause(job);
         aio_context_release(aio_context);
+    }
+
+    while ((bs = bdrv_next(bs))) {
+        AioContext *aio_context = bdrv_get_aio_context(bs);
 
         if (!aio_ctxs || !g_slist_find(aio_ctxs, aio_context)) {
             aio_ctxs = g_slist_prepend(aio_ctxs, aio_context);
@@ -309,14 +312,11 @@ void bdrv_drain_all(void)
         }
     }
 
-    bs = NULL;
-    while ((bs = bdrv_next(bs))) {
-        AioContext *aio_context = bdrv_get_aio_context(bs);
+    while ((job = block_job_next(job))) {
+        AioContext *aio_context = bdrv_get_aio_context(job->bs);
 
         aio_context_acquire(aio_context);
-        if (bs->job) {
-            block_job_resume(bs->job);
-        }
+        block_job_resume(job);
         aio_context_release(aio_context);
     }
     g_slist_free(aio_ctxs);
diff --git a/blockdev.c b/blockdev.c
index 41d7e0f..66f8515 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -3088,21 +3088,18 @@ fail:
 BlockJobInfoList *qmp_query_block_jobs(Error **errp)
 {
     BlockJobInfoList *head = NULL, **p_next = &head;
-    BlockDriverState *bs;
+    BlockJob *job;
 
-    for (bs = bdrv_next(NULL); bs; bs = bdrv_next(bs)) {
-        AioContext *aio_context = bdrv_get_aio_context(bs);
+    for (job = block_job_next(NULL); job; job = block_job_next(job)) {
+        BlockJobInfoList *elem = g_new0(BlockJobInfoList, 1);
+        AioContext *aio_context = bdrv_get_aio_context(job->bs);
 
         aio_context_acquire(aio_context);
-
-        if (bs->job) {
-            BlockJobInfoList *elem = g_new0(BlockJobInfoList, 1);
-            elem->value = block_job_query(bs->job);
-            *p_next = elem;
-            p_next = &elem->next;
-        }
-
+        elem->value = block_job_query(job);
         aio_context_release(aio_context);
+
+        *p_next = elem;
+        p_next = &elem->next;
     }
 
     return head;
diff --git a/blockjob.c b/blockjob.c
index 2755465..c46984d 100644
--- a/blockjob.c
+++ b/blockjob.c
@@ -35,6 +35,16 @@
 #include "qemu/timer.h"
 #include "qapi-event.h"
 
+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)
@@ -73,6 +83,8 @@ void *block_job_create(const BlockJobDriver *driver, 
BlockDriverState *bs,
             return NULL;
         }
     }
+
+    QLIST_INSERT_HEAD(&block_jobs, job, job_list);
     return job;
 }
 
@@ -85,6 +97,7 @@ void block_job_completed(BlockJob *job, int ret)
     bs->job = NULL;
     bdrv_op_unblock_all(bs, job->blocker);
     error_free(job->blocker);
+    QLIST_REMOVE(job, job_list);
     g_free(job);
 }
 
diff --git a/include/block/blockjob.h b/include/block/blockjob.h
index 57d8ef1..5431dd2 100644
--- a/include/block/blockjob.h
+++ b/include/block/blockjob.h
@@ -102,6 +102,9 @@ struct BlockJob {
      */
     bool ready;
 
+    /** 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;
 
@@ -125,6 +128,17 @@ struct BlockJob {
 };
 
 /**
+ * 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.
  * @bs: The block
-- 
2.1.4