Re: [PATCH v4 12/16] block/io: support int64_t bytes in bdrv_co_do_copy_on_readv()

[Eric Blake <eblake@redhat.com>]

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_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>
> ---
>  block/io.c         | 8 +++++---
>  block/trace-events | 2 +-
>  2 files changed, 6 insertions(+), 4 deletions(-)
> 

Reviewed-by: Eric Blake <eblake@redhat.com>

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3226
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