Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.
Ming Lin <mlin at kernel.org> writes:
> diff --git a/block/blk-core.c b/block/blk-core.c
> index fd154b9..909f317 100644
> --- a/block/blk-core.c
> +++ b/block/blk-core.c
> @@ -617,6 +617,10 @@ struct request_queue *blk_alloc_queue_node(gfp_t gfp_mask, int node_id)
> if (q->id < 0)
> goto fail_q;
>
> + q->bio_split = bioset_create(4, 0);
> + if (!q->bio_split)
> + goto fail_id;
> +
Arbitrary numbers should be documented.
> +static struct bio *blk_bio_discard_split(struct request_queue *q,
> + struct bio *bio,
> + struct bio_set *bs)
> +{
> + unsigned int max_discard_sectors, granularity;
> + int alignment;
> + sector_t tmp;
> + unsigned split_sectors;
> +
> + /* Zero-sector (unknown) and one-sector granularities are the same. */
> + granularity = max(q->limits.discard_granularity >> 9, 1U);
> +
> + max_discard_sectors = min(q->limits.max_discard_sectors, UINT_MAX >> 9);
> + max_discard_sectors -= max_discard_sectors % granularity;
> +
> + if (unlikely(!max_discard_sectors)) {
> + /* XXX: warn */
> + return NULL;
> + }
> +
> + if (bio_sectors(bio) <= max_discard_sectors)
> + return NULL;
> +
> + split_sectors = max_discard_sectors;
> +
> + /*
> + * If the next starting sector would be misaligned, stop the discard at
> + * the previous aligned sector.
> + */
> + alignment = (q->limits.discard_alignment >> 9) % granularity;
> +
> + tmp = bio->bi_iter.bi_sector + split_sectors - alignment;
> + tmp = sector_div(tmp, granularity);
> +
> + if (split_sectors > tmp)
> + split_sectors -= tmp;
> +
> + return bio_split(bio, split_sectors, GFP_NOIO, bs);
Much of this function is cut-n-paste from blk-lib.c. Is there any way
to factor it out?
> +static struct bio *blk_bio_segment_split(struct request_queue *q,
> + struct bio *bio,
> + struct bio_set *bs)
> +{
Funny name for a function that also merges segments. ;-) I admit I am
at a loss for coming up with a better name that won't overflow 80
columns.
Other than that, this looks sane.
Cheers,
Jeff