Re: [PATCH v1 23/54] bcache: handle bio_clone() & bvec updating for multipage bvecs

From: Ming Lei
Date: Sat Dec 31 2016 - 05:29:45 EST


Hi Coly,

On Fri, Dec 30, 2016 at 7:01 PM, Coly Li <i@xxxxxxx> wrote:
> On 2016/12/27 äå11:56, Ming Lei wrote:
>> The incoming bio may be too big to be cloned into
>> one singlepage bvecs bio, so split the bio and
>> check the splitted bio one by one.
>>
>> Signed-off-by: Ming Lei <tom.leiming@xxxxxxxxx>
>> ---
>> drivers/md/bcache/debug.c | 24 ++++++++++++++++++++++--
>> 1 file changed, 22 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/md/bcache/debug.c b/drivers/md/bcache/debug.c
>> index 48d03e8b3385..18b2d2d138e3 100644
>> --- a/drivers/md/bcache/debug.c
>> +++ b/drivers/md/bcache/debug.c
>> @@ -103,7 +103,7 @@ void bch_btree_verify(struct btree *b)
>> up(&b->io_mutex);
>> }
>>
>> -void bch_data_verify(struct cached_dev *dc, struct bio *bio)
>> +static void __bch_data_verify(struct cached_dev *dc, struct bio *bio)
>> {
>> char name[BDEVNAME_SIZE];
>> struct bio *check;
>> @@ -116,7 +116,7 @@ void bch_data_verify(struct cached_dev *dc, struct bio *bio)
>> * in the new cloned bio because each single page need
>> * to assign to each bvec of the new bio.
>> */
>> - check = bio_clone(bio, GFP_NOIO);
>> + check = bio_clone_sp(bio, GFP_NOIO);
>> if (!check)
>> return;
>> check->bi_opf = REQ_OP_READ;
>> @@ -151,6 +151,26 @@ void bch_data_verify(struct cached_dev *dc, struct bio *bio)
>> bio_put(check);
>> }
>>
>> +void bch_data_verify(struct cached_dev *dc, struct bio *bio)
>> +{
>> + struct request_queue *q = bdev_get_queue(bio->bi_bdev);
>> + struct bio *clone = bio_clone_fast(bio, GFP_NOIO, q->bio_split);
>> + unsigned sectors;
>> +
>> + while (!bio_can_convert_to_sp(clone, &sectors)) {
>> + struct bio *split = bio_split(clone, sectors,
>> + GFP_NOIO, q->bio_split);
>> +
>> + __bch_data_verify(dc, split);
>> + bio_put(split);
>> + }
>> +
>> + if (bio_sectors(clone))
>> + __bch_data_verify(dc, clone);
>> +
>> + bio_put(clone);
>> +}
>> +
>
> Hi Lei,
>
> The above patch is good IMHO. Just wondering why not use the classical
> style ? something like,

I don't know there is the classical style, :-)

>
>
> do {
> if (!bio_can_convert_to_sp(clone, &sectors))
> split = bio_split(clone, sectors,
> GFP_NOIO, q->bio_split);
> else
> split = clone;
>
> __bch_data_verity(gc, split);
> bio_put(split);
> } while (split != clone);
>
>
> I guess maybe the above style generates less binary code.

Maybe, will take this style in V2.

Thanks for the review!

--
Ming Lei