On 12/11/20 12:39 PM, Vladimir Sementsov-Ogievskiy wrote:
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_aligned_preadv() now.
Make byte variable in bdrv_padding_rmw_read() int64_t, as it defined
only to be passed to bdrv_aligned_preadv().
Reads awkwardly, how about:
Make the byte variable in bdrv_padding_rmw_read() int64_t, as it is only
used for pass-through to bdrv_aligned_preadv().
All bdrv_aligned_preadv() callers are safe as type is widening. Let's
look inside:
- add a new-style assertion that request is good.
- callees bdrv_is_allocated(), bdrv_co_do_copy_on_readv() supports
int64_t bytes
- conversion of bytes_remaining is OK, as we never has requests
have
overflowing BDRV_MAX_LENGTH
- looping through bytes_remaining is ok, num is updated to int64_t
- for bdrv_driver_preadv we have same limit of max_transfer
- qemu_iovec_memset is OK, as bytes+qiov_offset should not overflow
qiov->size anyway (thanks to bdrv_check_qiov_request())
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
---
block/io.c | 9 +++++----
1 file changed, 5 insertions(+), 4 deletions(-)
Reviewed-by: Eric Blake <eblake@redhat.com>