block: use int64_t instead of uint64_t in driver read handlers

We are generally moving to int64_t for both offset and bytes parameters
on all io paths.

Main motivation is realization of 64-bit write_zeroes operation for
fast zeroing large disk chunks, up to the whole disk.

We chose signed type, to be consistent with off_t (which is signed) and
with possibility for signed return type (where negative value means
error).

So, convert driver read handlers parameters which are already 64bit to
signed type.

While being here, convert also flags parameter to be BdrvRequestFlags.

Now let's consider all callers. Simple

  git grep '\->bdrv_\(aio\|co\)_preadv\(_part\)\?'

shows that's there three callers of driver function:

 bdrv_driver_preadv() in block/io.c, passes int64_t, checked by
   bdrv_check_qiov_request() to be non-negative.

 qcow2_load_vmstate() does bdrv_check_qiov_request().

 do_perform_cow_read() has uint64_t argument. And a lot of things in
 qcow2 driver are uint64_t, so converting it is big job. But we must
 not work with requests that don't satisfy bdrv_check_qiov_request(),
 so let's just assert it here.

Still, the functions may be called directly, not only by drv->...
Let's check:

git grep '\.bdrv_\(aio\|co\)_preadv\(_part\)\?\s*=' | \
awk '{print $4}' | sed 's/,//' | sed 's/&//' | sort | uniq | \
while read func; do git grep "$func(" | \
grep -v "$func(BlockDriverState"; done

The only one such caller:

    QEMUIOVector qiov = QEMU_IOVEC_INIT_BUF(qiov, &data, 1);
    ...
    ret = bdrv_replace_test_co_preadv(bs, 0, 1, &qiov, 0);

in tests/unit/test-bdrv-drain.c, and it's OK obviously.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-Id: <20210903102807.27127-4-vsementsov@virtuozzo.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
[eblake: fix typos]
Signed-off-by: Eric Blake <eblake@redhat.com>

1 files changed, 9 insertions, 7 deletions

diff --git a/tests/unit/test-bdrv-drain.c b/tests/unit/test-bdrv-drain.c
index ce071b5fc5..2d3c17e566 100644
--- a/tests/unit/test-bdrv-drain.c
+++ b/tests/unit/test-bdrv-drain.c
@@ -65,8 +65,9 @@ static void co_reenter_bh(void *opaque)
 }
 
 static int coroutine_fn bdrv_test_co_preadv(BlockDriverState *bs,
-                                            uint64_t offset, uint64_t bytes,
-                                            QEMUIOVector *qiov, int flags)
+                                            int64_t offset, int64_t bytes,
+                                            QEMUIOVector *qiov,
+                                            BdrvRequestFlags flags)
 {
     BDRVTestState *s = bs->opaque;
 
@@ -1106,8 +1107,9 @@ static void bdrv_test_top_close(BlockDriverState *bs)
 }
 
 static int coroutine_fn bdrv_test_top_co_preadv(BlockDriverState *bs,
-                                                uint64_t offset, uint64_t bytes,
-                                                QEMUIOVector *qiov, int flags)
+                                                int64_t offset, int64_t bytes,
+                                                QEMUIOVector *qiov,
+                                                BdrvRequestFlags flags)
 {
     BDRVTestTopState *tts = bs->opaque;
     return bdrv_co_preadv(tts->wait_child, offset, bytes, qiov, flags);
@@ -1855,10 +1857,10 @@ static void bdrv_replace_test_close(BlockDriverState *bs)
  *   Set .has_read to true and return success.
  */
 static int coroutine_fn bdrv_replace_test_co_preadv(BlockDriverState *bs,
-                                                    uint64_t offset,
-                                                    uint64_t bytes,
+                                                    int64_t offset,
+                                                    int64_t bytes,
                                                     QEMUIOVector *qiov,
-                                                    int flags)
+                                                    BdrvRequestFlags flags)
 {
     BDRVReplaceTestState *s = bs->opaque;