[Qemu-devel] [PATCH v2 05/12] block/io: bdrv_co_do_copy_on_readv: use and support qiov_offset

[Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>]

Use and support new API in bdrv_co_do_copy_on_readv. Note that in case
of allocated-in-top we need to shrink read size to MIN(..) by hand, as
pre-patch this was actually done implicitly by qemu_iovec_concat (and
we used local_qiov.size).

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
---
 block/io.c | 19 ++++++++++---------
 1 file changed, 10 insertions(+), 9 deletions(-)

diff --git a/block/io.c b/block/io.c
index 7e53a11492..efd2b80293 100644
--- a/block/io.c
+++ b/block/io.c
@@ -1161,7 +1161,8 @@ bdrv_driver_pwritev_compressed(BlockDriverState *bs, uint64_t offset,
 }
 
 static int coroutine_fn bdrv_co_do_copy_on_readv(BdrvChild *child,
-        int64_t offset, unsigned int bytes, QEMUIOVector *qiov)
+        int64_t offset, unsigned int bytes,
+        QEMUIOVector *qiov, size_t qiov_offset)
 {
     BlockDriverState *bs = child->bs;
 
@@ -1173,7 +1174,6 @@ static int coroutine_fn bdrv_co_do_copy_on_readv(BdrvChild *child,
     void *bounce_buffer;
 
     BlockDriver *drv = bs->drv;
-    QEMUIOVector local_qiov;
     int64_t cluster_offset;
     int64_t cluster_bytes;
     size_t skip_bytes;
@@ -1236,6 +1236,8 @@ static int coroutine_fn bdrv_co_do_copy_on_readv(BdrvChild *child,
         assert(skip_bytes < pnum);
 
         if (ret <= 0) {
+            QEMUIOVector local_qiov;
+
             /* Must copy-on-read; use the bounce buffer */
             pnum = MIN(pnum, MAX_BOUNCE_BUFFER);
             qemu_iovec_init_buf(&local_qiov, bounce_buffer, pnum);
@@ -1272,15 +1274,14 @@ static int coroutine_fn bdrv_co_do_copy_on_readv(BdrvChild *child,
                 goto err;
             }
 
-            qemu_iovec_from_buf(qiov, progress, bounce_buffer + skip_bytes,
+            qemu_iovec_from_buf(qiov, qiov_offset + progress,
+                                bounce_buffer + skip_bytes,
                                 pnum - skip_bytes);
         } else {
             /* Read directly into the destination */
-            qemu_iovec_init(&local_qiov, qiov->niov);
-            qemu_iovec_concat(&local_qiov, qiov, progress, pnum - skip_bytes);
-            ret = bdrv_driver_preadv(bs, offset + progress, local_qiov.size,
-                                     &local_qiov, 0, 0);
-            qemu_iovec_destroy(&local_qiov);
+            ret = bdrv_driver_preadv(bs, offset + progress,
+                                     MIN(pnum - skip_bytes, bytes - progress),
+                                     qiov, qiov_offset + progress, 0);
             if (ret < 0) {
                 goto err;
             }
@@ -1353,7 +1354,7 @@ static int coroutine_fn bdrv_aligned_preadv(BdrvChild *child,
         }
 
         if (!ret || pnum != bytes) {
-            ret = bdrv_co_do_copy_on_readv(child, offset, bytes, qiov);
+            ret = bdrv_co_do_copy_on_readv(child, offset, bytes, qiov, 0);
             goto out;
         }
     }
-- 
2.18.0