From f9e694cb32403c7ebe8f8cc6949da47896afd561 Mon Sep 17 00:00:00 2001
From: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Date: Thu, 24 Sep 2020 21:54:09 +0300
Subject: [PATCH] block/io: refactor coroutine wrappers
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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 parameter packing and calls bdrv_run_co().

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 an indirection layer, but it will be compensated by
a further commit, which will drop bdrv_co_prwv together with the
is_write logic, to keep the read and write paths separate.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-Id: <20200924185414.28642-3-vsementsov@virtuozzo.com>
---
 block/io.c | 60 +++++++++++++++++++++++++++++-------------------------
 1 file changed, 32 insertions(+), 28 deletions(-)

diff --git a/block/io.c b/block/io.c
index 11df1889f1..b4f6ab0ab1 100644
--- a/block/io.c
+++ b/block/io.c
@@ -933,27 +933,31 @@ 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 int coroutine_fn bdrv_rw_co_entry(void *opaque)
 {
     RwCo *rwco = opaque;
 
-    if (!rwco->is_write) {
-        return bdrv_co_preadv(rwco->child, rwco->offset,
-                              rwco->qiov->size, rwco->qiov,
-                              rwco->flags);
-    } else {
-        return bdrv_co_pwritev(rwco->child, rwco->offset,
-                               rwco->qiov->size, rwco->qiov,
-                               rwco->flags);
-    }
+    return bdrv_co_prwv(rwco->child, rwco->offset, rwco->qiov,
+                        rwco->is_write, rwco->flags);
 }
 
 /*
  * 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)
 {
     RwCo rwco = {
         .child = child,
@@ -971,8 +975,7 @@ 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);
 }
 
 /*
@@ -1021,7 +1024,7 @@ 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;
     }
@@ -1045,7 +1048,7 @@ 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;
     }
@@ -2449,14 +2452,15 @@ 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;
@@ -2494,10 +2498,10 @@ static int coroutine_fn bdrv_block_status_above_co_entry(void *opaque)
 {
     BdrvCoBlockStatusData *data = opaque;
 
-    return bdrv_co_block_status_above(data->bs, data->base,
-                                      data->want_zero,
-                                      data->offset, data->bytes,
-                                      data->pnum, data->map, data->file);
+    return bdrv_co_common_block_status_above(data->bs, data->base,
+                                             data->want_zero,
+                                             data->offset, data->bytes,
+                                             data->pnum, data->map, data->file);
 }
 
 /*