block/io: support int64_t bytes in bdrv_co_do_copy_on_readv()

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, prepare bdrv_co_do_copy_on_readv() now.

'bytes' type widening, so callers are safe. Look at the function
itself:

bytes, skip_bytes and progress become int64_t.

bdrv_round_to_clusters() is OK, cluster_bytes now may be large.
trace_bdrv_co_do_copy_on_readv() is OK

looping through cluster_bytes is still OK.

pnum is still capped to max_transfer, and to MAX_BOUNCE_BUFFER when we
are going to do COR operation. Therefor calculations in
qemu_iovec_from_buf() and bdrv_driver_preadv() should not change.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-Id: <20201211183934.169161-13-vsementsov@virtuozzo.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Eric Blake <eblake@redhat.com>

1 files changed, 5 insertions, 3 deletions

diff --git a/block/io.c b/block/io.c
index 59ae0a110d..63b0fa0e9e 100644
--- a/block/io.c
+++ b/block/io.c
@@ -1311,7 +1311,7 @@ bdrv_driver_pwritev_compressed(BlockDriverState *bs, int64_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, int64_t bytes, QEMUIOVector *qiov,
         size_t qiov_offset, int flags)
 {
     BlockDriverState *bs = child->bs;
@@ -1326,13 +1326,15 @@ static int coroutine_fn bdrv_co_do_copy_on_readv(BdrvChild *child,
     BlockDriver *drv = bs->drv;
     int64_t cluster_offset;
     int64_t cluster_bytes;
-    size_t skip_bytes;
+    int64_t skip_bytes;
     int ret;
     int max_transfer = MIN_NON_ZERO(bs->bl.max_transfer,
                                     BDRV_REQUEST_MAX_BYTES);
-    unsigned int progress = 0;
+    int64_t progress = 0;
     bool skip_write;
 
+    bdrv_check_qiov_request(offset, bytes, qiov, qiov_offset, &error_abort);
+
     if (!drv) {
         return -ENOMEDIUM;
     }