block-backend: update blk_co_pwrite() and blk_co_pread() wrappers

Make bytes argument int64_t to be consistent with modern block-layer.
Callers should be OK with it as type becomes wider.

What is inside functions?

- Conversion from int64_t to size_t. Still, we
can't have a buffer larger than SIZE_MAX, therefore bytes should not be
larger than SIZE_MAX as well. Add an assertion.

- Passing to blk_co_pwritev() / blk_co_preadv() which already has
  int64_t bytes argument.

Signed-off-by: Vladimir Sementsov-Ogievskiy <[email protected]>
Message-Id: <[email protected]>
Reviewed-by: Eric Blake <[email protected]>
[eblake: spelling fix]
Signed-off-by: Eric Blake <[email protected]>

Author: Vladimir Sementsov-Ogievskiy

include/sysemu/block-backend.h

@@ -137,20 +137,24 @@ int coroutine_fn blk_co_pwritev(BlockBackend *blk, int64_t offset,
                                BdrvRequestFlags flags);
 
 static inline int coroutine_fn blk_co_pread(BlockBackend *blk, int64_t offset,
-                                            unsigned int bytes, void *buf,
+                                            int64_t bytes, void *buf,
                                             BdrvRequestFlags flags)
 {
     QEMUIOVector qiov = QEMU_IOVEC_INIT_BUF(qiov, buf, bytes);
 
+    assert(bytes <= SIZE_MAX);
+
     return blk_co_preadv(blk, offset, bytes, &qiov, flags);
 }
 
 static inline int coroutine_fn blk_co_pwrite(BlockBackend *blk, int64_t offset,
-                                             unsigned int bytes, void *buf,
+                                             int64_t bytes, void *buf,
                                              BdrvRequestFlags flags)
 {
     QEMUIOVector qiov = QEMU_IOVEC_INIT_BUF(qiov, buf, bytes);
 
+    assert(bytes <= SIZE_MAX);
+
     return blk_co_pwritev(blk, offset, bytes, &qiov, flags);
 }