Most of our coroutine wrappers already follow this convention:

We have 'coroutine_fn bdrv_co_<something>(<normal argument list>)' as
the core function, and a wrapper 'bdrv_<something>(<same argument
list>)' which does a polling loop.

The only outsiders are the bdrv_prwv_co and
bdrv_common_block_status_above wrappers. Let's refactor them to behave
as the others, it simplifies further conversion of coroutine wrappers.

This patch adds indirection layer, but it will be compensated by
further commit, which will drop bdrv_co_prwv together with is_write
logic, to keep read and write patch separate.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
---
 block/io.c | 61 +++++++++++++++++++++++++++++-------------------------
 1 file changed, 33 insertions(+), 28 deletions(-)

diff --git a/block/io.c b/block/io.c
index 121ce17a49..bd00a70b47 100644
--- a/block/io.c
+++ b/block/io.c
@@ -900,28 +900,32 @@ typedef struct RwCo {
     BdrvRequestFlags flags;
 } RwCo;
 
+static int coroutine_fn bdrv_co_prwv(BdrvChild *child, int64_t offset,
+                                     QEMUIOVector *qiov, bool is_write,
+                                     BdrvRequestFlags flags)
+{
+    if (is_write) {
+        return bdrv_co_pwritev(child, offset, qiov->size, qiov, flags);
+    } else {
+        return bdrv_co_preadv(child, offset, qiov->size, qiov, flags);
+    }
+}
+
 static void coroutine_fn bdrv_rw_co_entry(void *opaque)
 {
     RwCo *rwco = opaque;
 
-    if (!rwco->is_write) {
-        rwco->ret = bdrv_co_preadv(rwco->child, rwco->offset,
-                                   rwco->qiov->size, rwco->qiov,
-                                   rwco->flags);
-    } else {
-        rwco->ret = bdrv_co_pwritev(rwco->child, rwco->offset,
-                                    rwco->qiov->size, rwco->qiov,
-                                    rwco->flags);
-    }
+    rwco->ret = bdrv_co_prwv(rwco->child, rwco->offset, rwco->qiov,
+                             rwco->is_write, rwco->flags);
     aio_wait_kick();
 }
 
 /*
  * Process a vectored synchronous request using coroutines
  */
-static int bdrv_prwv_co(BdrvChild *child, int64_t offset,
-                        QEMUIOVector *qiov, bool is_write,
-                        BdrvRequestFlags flags)
+static int bdrv_prwv(BdrvChild *child, int64_t offset,
+                     QEMUIOVector *qiov, bool is_write,
+                     BdrvRequestFlags flags)
 {
     Coroutine *co;
     RwCo rwco = {
@@ -949,8 +953,7 @@ int bdrv_pwrite_zeroes(BdrvChild *child, int64_t offset,
 {
     QEMUIOVector qiov = QEMU_IOVEC_INIT_BUF(qiov, NULL, bytes);
 
-    return bdrv_prwv_co(child, offset, &qiov, true,
-                        BDRV_REQ_ZERO_WRITE | flags);
+    return bdrv_prwv(child, offset, &qiov, true, BDRV_REQ_ZERO_WRITE | flags);
 }
 
 /*
@@ -999,7 +1002,7 @@ int bdrv_preadv(BdrvChild *child, int64_t offset, QEMUIOVector *qiov)
 {
     int ret;
 
-    ret = bdrv_prwv_co(child, offset, qiov, false, 0);
+    ret = bdrv_prwv(child, offset, qiov, false, 0);
     if (ret < 0) {
         return ret;
     }
@@ -1023,7 +1026,7 @@ int bdrv_pwritev(BdrvChild *child, int64_t offset, QEMUIOVector *qiov)
 {
     int ret;
 
-    ret = bdrv_prwv_co(child, offset, qiov, true, 0);
+    ret = bdrv_prwv(child, offset, qiov, true, 0);
     if (ret < 0) {
         return ret;
     }
@@ -2443,14 +2446,15 @@ early_out:
     return ret;
 }
 
-static int coroutine_fn bdrv_co_block_status_above(BlockDriverState *bs,
-                                                   BlockDriverState *base,
-                                                   bool want_zero,
-                                                   int64_t offset,
-                                                   int64_t bytes,
-                                                   int64_t *pnum,
-                                                   int64_t *map,
-                                                   BlockDriverState **file)
+static int coroutine_fn
+bdrv_co_common_block_status_above(BlockDriverState *bs,
+                                  BlockDriverState *base,
+                                  bool want_zero,
+                                  int64_t offset,
+                                  int64_t bytes,
+                                  int64_t *pnum,
+                                  int64_t *map,
+                                  BlockDriverState **file)
 {
     BlockDriverState *p;
     int ret = 0;
@@ -2488,10 +2492,11 @@ static void coroutine_fn bdrv_block_status_above_co_entry(void *opaque)
 {
     BdrvCoBlockStatusData *data = opaque;
 
-    data->ret = bdrv_co_block_status_above(data->bs, data->base,
-                                           data->want_zero,
-                                           data->offset, data->bytes,
-                                           data->pnum, data->map, data->file);
+    data->ret = bdrv_co_common_block_status_above(data->bs, data->base,
+                                                  data->want_zero,
+                                                  data->offset, data->bytes,
+                                                  data->pnum, data->map,
+                                                  data->file);
     data->done = true;
     aio_wait_kick();
 }
-- 
2.21.0