On Mon, Aug 13, 2018 at 04:19:52AM +0200, Max Reitz wrote:
> Signed-off-by: Max Reitz
Reviewed-by: Jeff Cody
> ---
> block/mirror.c | 54 +-
> 1 file changed, 36 insertions(+), 18 deletions(-)
>
> diff --git a/block/mirror.c b/block/mirror.c
> index c28b6159d5..34cb8293b2 100644
> --- a/block/mirror.c
> +++ b/block/mirror.c
> @@ -305,42 +305,60 @@ static inline void coroutine_fn
> mirror_co_wait_for_any_operation(s, false);
> }
>
> -/* Perform a mirror copy operation.
> +/*
> + * Restrict *bytes to how much we can actually handle, and align the
> + * [*offset, *bytes] range to clusters if COW is needed.
> *
> - * *op->bytes_handled is set to the number of bytes copied after and
> + * *bytes_handled is set to the number of bytes copied after and
> * including offset, excluding any bytes copied prior to offset due
> - * to alignment. This will be op->bytes if no alignment is necessary,
> - * or (new_end - op->offset) if the tail is rounded up or down due to
> + * to alignment. This will be *bytes if no alignment is necessary, or
> + * (new_end - *offset) if the tail is rounded up or down due to
> * alignment or buffer limit.
> */
> -static void coroutine_fn mirror_co_read(void *opaque)
> +static void mirror_align_for_copy(MirrorBlockJob *s,
> + int64_t *offset, uint64_t *bytes,
> + int64_t *bytes_handled)
> {
> -MirrorOp *op = opaque;
> -MirrorBlockJob *s = op->s;
> -int nb_chunks;
> -uint64_t ret;
> uint64_t max_bytes;
>
> max_bytes = s->granularity * s->max_iov;
>
> /* We can only handle as much as buf_size at a time. */
> -op->bytes = MIN(s->buf_size, MIN(max_bytes, op->bytes));
> -assert(op->bytes);
> -assert(op->bytes < BDRV_REQUEST_MAX_BYTES);
> -*op->bytes_handled = op->bytes;
> +*bytes = MIN(s->buf_size, MIN(max_bytes, *bytes));
> +assert(*bytes);
> +assert(*bytes < BDRV_REQUEST_MAX_BYTES);
> +*bytes_handled = *bytes;
>
> if (s->cow_bitmap) {
> -*op->bytes_handled += mirror_cow_align(s, >offset, >bytes);
> +*bytes_handled += mirror_cow_align(s, offset, bytes);
> }
> /* Cannot exceed BDRV_REQUEST_MAX_BYTES + INT_MAX */
> -assert(*op->bytes_handled <= UINT_MAX);
> -assert(op->bytes <= s->buf_size);
> +assert(*bytes_handled <= UINT_MAX);
> +assert(*bytes <= s->buf_size);
> /* The offset is granularity-aligned because:
> * 1) Caller passes in aligned values;
> * 2) mirror_cow_align is used only when target cluster is larger. */
> -assert(QEMU_IS_ALIGNED(op->offset, s->granularity));
> +assert(QEMU_IS_ALIGNED(*offset, s->granularity));
> /* The range is sector-aligned, since bdrv_getlength() rounds up. */
> -assert(QEMU_IS_ALIGNED(op->bytes, BDRV_SECTOR_SIZE));
> +assert(QEMU_IS_ALIGNED(*bytes, BDRV_SECTOR_SIZE));
> +}
> +
> +/* Perform a mirror copy operation.
> + *
> + * *op->bytes_handled is set to the number of bytes copied after and
> + * including offset, excluding any bytes copied prior to offset due
> + * to alignment. This will be op->bytes if no alignment is necessary,
> + * or (new_end - op->offset) if the tail is rounded up or down due to
> + * alignment or buffer limit.
> + */
> +static void coroutine_fn mirror_co_read(void *opaque)
> +{
> +MirrorOp *op = opaque;
> +MirrorBlockJob *s = op->s;
> +int nb_chunks;
> +uint64_t ret;
> +
> +mirror_align_for_copy(s, >offset, >bytes, op->bytes_handled);
> nb_chunks = DIV_ROUND_UP(op->bytes, s->granularity);
>
> while (s->buf_free_count < nb_chunks) {
> --
> 2.17.1
>
