file-posix: Better checks of 64-bit copy_range

file-posix.c was taking a 64-bit bytes in raw_co_copy_range_to(), passing it through a 32-bit parameter of paio_submit_co_full(), then widening it back to size_t when assigning into acb->aio_nbytes.

Looking at io.c, I can't quickly tell if bdrv_co_copy_range_internal() is fragmenting things to honor bs->bl.max_transfer, or if it can accidentally send requests larger than 2G down to the driver. If the former, then this is a no-op; if the latter, then someone needs to find a way to trigger this assertion and patch the block layer to properly fragment copy_range requests. Either way, we're better off with an assertion than the risk of silent data corruption.

Signed-off-by Eric Blake <[email protected]>

---
  block/file-posix.c | 5 +++--
  1 file changed, 3 insertions(+), 2 deletions(-)

block/file-posix.c +3 -2

index 58c86a01eaa..48ad3bb372a 100644
@@ -1821,7 +1821,7 @@ static int aio_worker(void *arg)
  static int paio_submit_co_full(BlockDriverState *bs, int fd,
                                 int64_t offset, int fd2, int64_t offset2,
                                 QEMUIOVector *qiov,
-                               int bytes, int type)
+                               uint64_t bytes, int type)
  {
      RawPosixAIOData *acb = g_new(RawPosixAIOData, 1);
      ThreadPool *pool;

@@ -1832,6 +1832,7 @@ static int paio_submit_co_full(BlockDriverState *bs, int fd,
      acb->aio_fd2 = fd2;
      acb->aio_offset2 = offset2;
 
+    assert(bytes <= SIZE_MAX);
      acb->aio_nbytes = bytes;
      acb->aio_offset = offset;
 

@@ -1848,7 +1849,7 @@ static int paio_submit_co_full(BlockDriverState *bs, int fd,
 
  static inline int paio_submit_co(BlockDriverState *bs, int fd,
                                   int64_t offset, QEMUIOVector *qiov,
-                                 int bytes, int type)
+                                 uint64_t bytes, int type)
  {
      return paio_submit_co_full(bs, fd, offset, -1, 0, qiov, bytes, type);
  }