Use generic infrastructure for BAT writing in parallels_co_check()
On 11.08.2022 17:00, Alexander Ivanov wrote:
> It's too costly to write all the BAT to the disk. Let the flush function
> write only dirty blocks.
> Use parallels_set_bat_entry for setting a BAT entry and marking a relevant
> block as dirty.
> Move bdrv_co_flush call outside the locked area.
This is not correct too:
- with a lot of cases inside parallels_co_check, which will be split to
smaller functions, we would like to avoid writing BAT once each
stage is complete
Thus the comment should look like the following:
"BAT is written in the context of conventional operations over
the image inside bdrv_co_flush() when it calls
parallels_co_flush_to_os() callback. Thus we should not
modify BAT array directly, but call parallels_set_bat_entry()
helper and bdrv_co_flush() further on. After that there is no
need to manually write BAT and track its modification.
This makes code more generic and allows to split
parallels_set_bat_entry() for independent pieces."
> v2: Patch order was changed so the replacement is done in parallels_co_check.
> Now we use a helper to set BAT entry and mark the block dirty.
Same note about changelog as n other patches.
Side note. I like Linux kernel a lot and there is a good
guide in. Please look how commit message
https://www.kernel.org/doc/html/latest/process/submitting-patches.html
May be you could spend some more time on commit
message.
With a better message:
Reviewed-by: Denis V. Lunev <den@openvz.org>
> Signed-off-by: Alexander Ivanov <alexander.ivanov@virtuozzo.com>
> ---
> block/parallels.c | 19 +++++++------------
> 1 file changed, 7 insertions(+), 12 deletions(-)
>
> diff --git a/block/parallels.c b/block/parallels.c
> index 7f68f3cbc9..6879ea4597 100644
> --- a/block/parallels.c
> +++ b/block/parallels.c
> @@ -428,7 +428,6 @@ static int coroutine_fn parallels_co_check(BlockDriverState *bs,
> int64_t size, prev_off, high_off;
> int ret;
> uint32_t i;
> - bool flush_bat = false;
>
> size = bdrv_getlength(bs->file->bs);
> if (size < 0) {
> @@ -467,9 +466,8 @@ static int coroutine_fn parallels_co_check(BlockDriverState *bs,
> res->corruptions++;
> if (fix & BDRV_FIX_ERRORS) {
> prev_off = 0;
> - s->bat_bitmap[i] = 0;
> + parallels_set_bat_entry(s, i, 0);
> res->corruptions_fixed++;
> - flush_bat = true;
> continue;
> }
> }
> @@ -485,15 +483,6 @@ static int coroutine_fn parallels_co_check(BlockDriverState *bs,
> prev_off = off;
> }
>
> - ret = 0;
> - if (flush_bat) {
> - ret = bdrv_co_pwrite_sync(bs->file, 0, s->header_size, s->header, 0);
> - if (ret < 0) {
> - res->check_errors++;
> - goto out;
> - }
> - }
> -
> res->image_end_offset = high_off + s->cluster_size;
> if (size > res->image_end_offset) {
> int64_t count;
> @@ -522,6 +511,12 @@ static int coroutine_fn parallels_co_check(BlockDriverState *bs,
>
> out:
> qemu_co_mutex_unlock(&s->lock);
> +
> + ret = bdrv_co_flush(bs);
> + if (ret < 0) {
> + res->check_errors++;
> + }
> +
> return ret;
> }
>