On Mon, Sep 24, 2012 at 03:34:46PM -0700, Kent Overstreet wrote:
> Just a little convenience macro - main reason to add it now is preparing
> for immutable bio vecs, it'll reduce the size of the patch that puts
> bi_sector/bi_size/bi_idx into a struct bvec_iter.
For the DRBD part:
> diff --git a/drivers/block/drbd/drbd_req.c b/drivers/block/drbd/drbd_req.c
> index 01b2ac6..d90a1fd 100644
> --- a/drivers/block/drbd/drbd_req.c
> +++ b/drivers/block/drbd/drbd_req.c
> @@ -1144,7 +1144,7 @@ void drbd_make_request(struct request_queue *q, struct
> bio *bio)
> /* to make some things easier, force alignment of requests within the
> * granularity of our hash tables */
> s_enr = bio->bi_sector >> HT_SHIFT;
> - e_enr = bio->bi_size ? (bio->bi_sector+(bio->bi_size>>9)-1) >> HT_SHIFT
> : s_enr;
> + e_enr = (bio_end_sector(bio) - 1) >> HT_SHIFT;
You ignored the bio->bi_size ? : ;
#define bio_end_sector(bio) ((bio)->bi_sector + bio_sectors(bio))
which turns out (bio->bi_sector + (bio->bi_size >> 9))
Note that bi_size may be 0, bio_end_sector(bio)-1 then is bi_sector -1,
for an empty flush with bi_sector == 0, this ends up as (sector_t)-1ULL,
and this code path breaks horribly.
+ e_enr = bio->bi_size ? (bio_end_sector(bio) - 1) >> HT_SHIFT : s_enr;
Thanks,
Lars
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