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_pwrite_zeroes() now. Patch-correctness audit by Eric Blake: Widens from 32- to 64-bit. Callers: bdrv_co_do_copy_on_readv() - passes 'int64_t pnum' bounded by fragmenting loop limited to MAX_BOUNCE_BUFFER bdrv_aligned_pwritev() - passes 'unsigned int bytes' - latent bug fix for sizes between 2G and 4G, if any to see if that bug could be tickled, look at callers of bdrv_aligned_pwritev: bdrv_co_do_zero_pwritev() - splits 'unsigned int bytes' into head|body|tail; head and tail are safe but body could be > 2G bdrv_co_pwritev_part() - gates with bdrv_check_byte_request() continuing the audit, callers of bdrv_co_do_zero_pwritev: bdrv_co_pwritev_part() - gates with bdrv_check_byte_request() okay, all callers pass < 2G per our current code in bdrv_check_byte_request(), so there is no actual bug. Use of 'bytes' within the function: compute 'int tail' via % 'int alignment' - safe fragmentation loop 'int num' - still fragments with a cap on max_transfer use of 'num' within the loop compute 'int head' via % 'int alignment' - safe clamp size by 'int max_write_zeroes' - safe drv->bdrv_co_pwrite_zeroes(int) - safe because of clamping clamp size by 'int max_transfer' - safe qemu_iovec_init_buf(size_t) - safe because of clamping bdrv_driver_pwritev(uint64_t) [well, int64_t after 4/17] - safe So even with the wider type, we aren't exceeding the contract of anything we pass it on to. Later patches may improve drv->bdrv_co_pwrite_zeroes and qemu_iovec_init_buf to be 64-bit clean, at which point we would want to revisit this function to use 64-bit clamping rather than 32-bit clamping, but it does not have to happen here. Series: 64bit-block-status Signed-off-by: Vladimir Sementsov-Ogievskiy <vsement...@virtuozzo.com> Reviewed-by: Eric Blake <ebl...@redhat.com> --- block/io.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/block/io.c b/block/io.c index eeba3b828c..b83749cc50 100644 --- a/block/io.c +++ b/block/io.c @@ -42,7 +42,7 @@ static void bdrv_parent_cb_resize(BlockDriverState *bs); static int coroutine_fn bdrv_co_do_pwrite_zeroes(BlockDriverState *bs, - int64_t offset, int bytes, BdrvRequestFlags flags); + int64_t offset, int64_t bytes, BdrvRequestFlags flags); static void bdrv_parent_drained_begin(BlockDriverState *bs, BdrvChild *ignore, bool ignore_bds_parents) @@ -1575,7 +1575,7 @@ int coroutine_fn bdrv_co_preadv_part(BdrvChild *child, } static int coroutine_fn bdrv_co_do_pwrite_zeroes(BlockDriverState *bs, - int64_t offset, int bytes, BdrvRequestFlags flags) + int64_t offset, int64_t bytes, BdrvRequestFlags flags) { BlockDriver *drv = bs->drv; QEMUIOVector qiov; @@ -1605,7 +1605,7 @@ static int coroutine_fn bdrv_co_do_pwrite_zeroes(BlockDriverState *bs, assert(max_write_zeroes >= bs->bl.request_alignment); while (bytes > 0 && !ret) { - int num = bytes; + int64_t num = bytes; /* Align request. Block drivers can expect the "bulk" of the request * to be aligned, and that unaligned requests do not cross cluster -- 2.21.0