[Qemu-block] [PATCH v2 3/5] block: Introduce and make use of blk_new_with_root

[Fam Zheng]

The idiom of "blk_new() + blk_insert_bs()" is common. Use a new
BB interface that does both things to make the coming transition that
adds AioContext to BB easier.

The added blk_new_with_ctx doesn't handle the passed ctx and is purely
here to avoid a small code churn.

Signed-off-by: Fam Zheng <address@hidden>
---
 block/backup.c                   |  3 +--
 block/block-backend.c            | 24 ++++++++++++++++++------
 block/commit.c                   | 12 ++++--------
 block/mirror.c                   |  3 +--
 blockjob.c                       |  3 +--
 hmp.c                            |  3 +--
 hw/core/qdev-properties-system.c |  3 +--
 include/sysemu/block-backend.h   |  1 +
 nbd/server.c                     |  3 +--
 tests/test-blockjob.c            |  3 +--
 10 files changed, 30 insertions(+), 28 deletions(-)

diff --git a/block/backup.c b/block/backup.c
index 582bd0f..3eed9a1 100644
--- a/block/backup.c
+++ b/block/backup.c
@@ -601,8 +601,7 @@ void backup_start(const char *job_id, BlockDriverState *bs,
         goto error;
     }
 
-    job->target = blk_new();
-    blk_insert_bs(job->target, target);
+    job->target = blk_new_with_root(target);
 
     job->on_source_error = on_source_error;
     job->on_target_error = on_target_error;
diff --git a/block/block-backend.c b/block/block-backend.c
index 0bd19ab..b71babe 100644
--- a/block/block-backend.c
+++ b/block/block-backend.c
@@ -115,12 +115,7 @@ static const BdrvChildRole child_root = {
     .drained_end        = blk_root_drained_end,
 };
 
-/*
- * Create a new BlockBackend with a reference count of one.
- * Store an error through @errp on failure, unless it's null.
- * Return the new BlockBackend on success, null on failure.
- */
-BlockBackend *blk_new(void)
+static BlockBackend *blk_new_with_ctx(AioContext *ctx)
 {
     BlockBackend *blk;
 
@@ -139,6 +134,23 @@ BlockBackend *blk_new(void)
 }
 
 /*
+ * Create a new BlockBackend with a reference count of one.
+ * Store an error through @errp on failure, unless it's null.
+ * Return the new BlockBackend on success, null on failure.
+ */
+BlockBackend *blk_new(void)
+{
+    return blk_new_with_ctx(qemu_get_aio_context());
+}
+
+BlockBackend *blk_new_with_root(BlockDriverState *root)
+{
+    BlockBackend *blk = blk_new_with_ctx(bdrv_get_aio_context(root));
+    blk_insert_bs(blk, root);
+    return blk;
+}
+
+/*
  * Creates a new BlockBackend, opens a new BlockDriverState, and connects both.
  *
  * Just as with bdrv_open(), after having called this function the reference to
diff --git a/block/commit.c b/block/commit.c
index 9f67a8b..45d4f96 100644
--- a/block/commit.c
+++ b/block/commit.c
@@ -260,11 +260,9 @@ void commit_start(const char *job_id, BlockDriverState *bs,
     }
 
 
-    s->base = blk_new();
-    blk_insert_bs(s->base, base);
+    s->base = blk_new_with_root(base);
 
-    s->top = blk_new();
-    blk_insert_bs(s->top, top);
+    s->top = blk_new_with_root(top);
 
     s->active = bs;
 
@@ -314,11 +312,9 @@ int bdrv_commit(BlockDriverState *bs)
         }
     }
 
-    src = blk_new();
-    blk_insert_bs(src, bs);
+    src = blk_new_with_root(bs);
 
-    backing = blk_new();
-    blk_insert_bs(backing, bs->backing->bs);
+    backing = blk_new_with_root(bs->backing->bs);
 
     length = blk_getlength(src);
     if (length < 0) {
diff --git a/block/mirror.c b/block/mirror.c
index f9d1fec..8910d53 100644
--- a/block/mirror.c
+++ b/block/mirror.c
@@ -941,8 +941,7 @@ static void mirror_start_job(const char *job_id, 
BlockDriverState *bs,
         return;
     }
 
-    s->target = blk_new();
-    blk_insert_bs(s->target, target);
+    s->target = blk_new_with_root(target);
 
     s->replaces = g_strdup(replaces);
     s->on_source_error = on_source_error;
diff --git a/blockjob.c b/blockjob.c
index a167f96..8fe6d5d 100644
--- a/blockjob.c
+++ b/blockjob.c
@@ -148,8 +148,7 @@ void *block_job_create(const char *job_id, const 
BlockJobDriver *driver,
         return NULL;
     }
 
-    blk = blk_new();
-    blk_insert_bs(blk, bs);
+    blk = blk_new_with_root(bs);
 
     job = g_malloc0(driver->instance_size);
     error_setg(&job->blocker, "block device is in use by block job: %s",
diff --git a/hmp.c b/hmp.c
index 336e7bf..1ee83d2 100644
--- a/hmp.c
+++ b/hmp.c
@@ -1934,8 +1934,7 @@ void hmp_qemu_io(Monitor *mon, const QDict *qdict)
     if (!blk) {
         BlockDriverState *bs = bdrv_lookup_bs(NULL, device, &err);
         if (bs) {
-            blk = local_blk = blk_new();
-            blk_insert_bs(blk, bs);
+            blk = local_blk = blk_new_with_root(bs);
         } else {
             goto fail;
         }
diff --git a/hw/core/qdev-properties-system.c b/hw/core/qdev-properties-system.c
index e55afe6..2b07beb 100644
--- a/hw/core/qdev-properties-system.c
+++ b/hw/core/qdev-properties-system.c
@@ -78,8 +78,7 @@ static void parse_drive(DeviceState *dev, const char *str, 
void **ptr,
     if (!blk) {
         BlockDriverState *bs = bdrv_lookup_bs(NULL, str, NULL);
         if (bs) {
-            blk = blk_new();
-            blk_insert_bs(blk, bs);
+            blk = blk_new_with_root(bs);
             blk_created = true;
         }
     }
diff --git a/include/sysemu/block-backend.h b/include/sysemu/block-backend.h
index 3b29317..a25ee69 100644
--- a/include/sysemu/block-backend.h
+++ b/include/sysemu/block-backend.h
@@ -79,6 +79,7 @@ typedef struct BlockBackendPublic {
 } BlockBackendPublic;
 
 BlockBackend *blk_new(void);
+BlockBackend *blk_new_with_root(BlockDriverState *root);
 BlockBackend *blk_new_open(const char *filename, const char *reference,
                            QDict *options, int flags, Error **errp);
 int blk_get_refcnt(BlockBackend *blk);
diff --git a/nbd/server.c b/nbd/server.c
index 472f584..c965cce 100644
--- a/nbd/server.c
+++ b/nbd/server.c
@@ -816,8 +816,7 @@ NBDExport *nbd_export_new(BlockDriverState *bs, off_t 
dev_offset, off_t size,
     BlockBackend *blk;
     NBDExport *exp = g_malloc0(sizeof(NBDExport));
 
-    blk = blk_new();
-    blk_insert_bs(blk, bs);
+    blk = blk_new_with_root(bs);
     blk_set_enable_write_cache(blk, !writethrough);
 
     exp->refcount = 1;
diff --git a/tests/test-blockjob.c b/tests/test-blockjob.c
index 5b0e934..74dc750 100644
--- a/tests/test-blockjob.c
+++ b/tests/test-blockjob.c
@@ -53,10 +53,9 @@ static BlockJob *do_test_id(BlockBackend *blk, const char 
*id,
  * BlockDriverState inserted. */
 static BlockBackend *create_blk(const char *name)
 {
-    BlockBackend *blk = blk_new();
     BlockDriverState *bs = bdrv_new();
+    BlockBackend *blk = blk_new_with_root(bs);
 
-    blk_insert_bs(blk, bs);
     bdrv_unref(bs);
 
     if (name) {
-- 
2.7.4