rbd: shift byte count as a 64-bit value

Otherwise, reads of more than 2GB fail.  Until commit
7bbca9e, reads of 2^41
bytes succeeded at least theoretically.

In fact, pdiscard ought to receive a 64-bit integer as the
count for the same reason.

Reported by Coverity.

Fixes: 7bbca9e
Cc: qemu-stable@nongnu.org
Cc: kwolf@redhat.com
Cc: eblake@redhat.com
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

block/rbd.c

@@ -733,7 +733,7 @@ static BlockAIOCB *qemu_rbd_aio_readv(BlockDriverState *bs,
                                       void *opaque)
 {
     return rbd_start_aio(bs, sector_num << BDRV_SECTOR_BITS, qiov,
-                         nb_sectors << BDRV_SECTOR_BITS, cb, opaque,
+                         (int64_t) nb_sectors << BDRV_SECTOR_BITS, cb, opaque,
                          RBD_AIO_READ);
 }
 
@@ -745,7 +745,7 @@ static BlockAIOCB *qemu_rbd_aio_writev(BlockDriverState *bs,
                                        void *opaque)
 {
     return rbd_start_aio(bs, sector_num << BDRV_SECTOR_BITS, qiov,
-                         nb_sectors << BDRV_SECTOR_BITS, cb, opaque,
+                         (int64_t) nb_sectors << BDRV_SECTOR_BITS, cb, opaque,
                          RBD_AIO_WRITE);
 }