On 7/20/22 23:24, Christoph Hellwig wrote:
> Only non-passthrough requests are split by the block layer and use the
> ->bio_split bio_set. Move it from the request_queue to the gendisk.
>
> Signed-off-by: Christoph Hellwig <hch@xxxxxx>
> ---
> block/blk-core.c | 9 +--------
> block/blk-merge.c | 20 ++++++++++----------
> block/blk-sysfs.c | 2 --
> block/genhd.c | 9 ++++++++-
> drivers/md/dm.c | 2 +-
> include/linux/blkdev.h | 3 ++-
> 6 files changed, 22 insertions(+), 23 deletions(-)
>
> diff --git a/block/blk-core.c b/block/blk-core.c
> index 123468b9d2e43..59f13d011949d 100644
> --- a/block/blk-core.c
> +++ b/block/blk-core.c
> @@ -377,7 +377,6 @@ static void blk_timeout_work(struct work_struct *work)
> struct request_queue *blk_alloc_queue(int node_id, bool alloc_srcu)
> {
> struct request_queue *q;
> - int ret;
>
> q = kmem_cache_alloc_node(blk_get_queue_kmem_cache(alloc_srcu),
> GFP_KERNEL | __GFP_ZERO, node_id);
> @@ -396,13 +395,9 @@ struct request_queue *blk_alloc_queue(int node_id, bool alloc_srcu)
> if (q->id < 0)
> goto fail_srcu;
>
> - ret = bioset_init(&q->bio_split, BIO_POOL_SIZE, 0, 0);
> - if (ret)
> - goto fail_id;
> -
> q->stats = blk_alloc_queue_stats();
> if (!q->stats)
> - goto fail_split;
> + goto fail_id;
>
> q->node = node_id;
>
> @@ -439,8 +434,6 @@ struct request_queue *blk_alloc_queue(int node_id, bool alloc_srcu)
>
> fail_stats:
> blk_free_queue_stats(q->stats);
> -fail_split:
> - bioset_exit(&q->bio_split);
> fail_id:
> ida_free(&blk_queue_ida, q->id);
> fail_srcu:
> diff --git a/block/blk-merge.c b/block/blk-merge.c
> index 3c3f785f558af..e657f1dc824cb 100644
> --- a/block/blk-merge.c
> +++ b/block/blk-merge.c
> @@ -328,26 +328,26 @@ static struct bio *blk_bio_segment_split(struct request_queue *q,
> * Split a bio into two bios, chain the two bios, submit the second half and
> * store a pointer to the first half in *@bio. If the second bio is still too
> * big it will be split by a recursive call to this function. Since this
> - * function may allocate a new bio from q->bio_split, it is the responsibility
> - * of the caller to ensure that q->bio_split is only released after processing
> - * of the split bio has finished.
> + * function may allocate a new bio from disk->bio_split, it is the
> + * responsibility of the caller to ensure that disk->bio_split is only released
> + * after processing of the split bio has finished.
> */
> void __blk_queue_split(struct request_queue *q, struct bio **bio,
> unsigned int *nr_segs)
> {
> + struct bio_set *bs = &(*bio)->bi_bdev->bd_disk->bio_split;
> struct bio *split = NULL;
>
> switch (bio_op(*bio)) {
> case REQ_OP_DISCARD:
> case REQ_OP_SECURE_ERASE:
> - split = blk_bio_discard_split(q, *bio, &q->bio_split, nr_segs);
> + split = blk_bio_discard_split(q, *bio, bs, nr_segs);
> break;
> case REQ_OP_WRITE_ZEROES:
> - split = blk_bio_write_zeroes_split(q, *bio, &q->bio_split,
> - nr_segs);
> + split = blk_bio_write_zeroes_split(q, *bio, bs, nr_segs);
> break;
> default:
> - split = blk_bio_segment_split(q, *bio, &q->bio_split, nr_segs);
> + split = blk_bio_segment_split(q, *bio, bs, nr_segs);
> break;
> }
Suggestion for a follow-up patch: we could save the *bio pointer in a
local variable instead of constantly de-referencing bio.
>
> @@ -368,9 +368,9 @@ void __blk_queue_split(struct request_queue *q, struct bio **bio,
> *
> * Split a bio into two bios, chains the two bios, submit the second half and
> * store a pointer to the first half in *@bio. Since this function may allocate
> - * a new bio from q->bio_split, it is the responsibility of the caller to ensure
> - * that q->bio_split is only released after processing of the split bio has
> - * finished.
> + * a new bio from disk->bio_split, it is the responsibility of the caller to
> + * ensure that disk->bio_split is only released after processing of the split
> + * bio has finished.
> */
> void blk_queue_split(struct bio **bio)
> {
> diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c
> index c0303026752d5..e1f009aba6fd2 100644
> --- a/block/blk-sysfs.c
> +++ b/block/blk-sysfs.c
> @@ -779,8 +779,6 @@ static void blk_release_queue(struct kobject *kobj)
> if (queue_is_mq(q))
> blk_mq_release(q);
>
> - bioset_exit(&q->bio_split);
> -
> if (blk_queue_has_srcu(q))
> cleanup_srcu_struct(q->srcu);
>
> diff --git a/block/genhd.c b/block/genhd.c
> index 44dfcf67ed96a..150494e8742b0 100644
> --- a/block/genhd.c
> +++ b/block/genhd.c
> @@ -1138,6 +1138,8 @@ static void disk_release(struct device *dev)
> might_sleep();
> WARN_ON_ONCE(disk_live(disk));
>
> + bioset_exit(&disk->bio_split);
> +
> blkcg_exit_queue(disk->queue);
>
> disk_release_events(disk);
> @@ -1330,9 +1332,12 @@ struct gendisk *__alloc_disk_node(struct request_queue *q, int node_id,
> if (!disk)
> goto out_put_queue;
>
> + if (bioset_init(&disk->bio_split, BIO_POOL_SIZE, 0, 0))
> + goto out_free_disk;
> +
> disk->bdi = bdi_alloc(node_id);
> if (!disk->bdi)
> - goto out_free_disk;
> + goto out_free_bioset;
>
> /* bdev_alloc() might need the queue, set before the first call */
> disk->queue = q;
> @@ -1370,6 +1375,8 @@ struct gendisk *__alloc_disk_node(struct request_queue *q, int node_id,
> iput(disk->part0->bd_inode);
> out_free_bdi:
> bdi_put(disk->bdi);
> +out_free_bioset:
> + bioset_exit(&disk->bio_split);
> out_free_disk:
> kfree(disk);
> out_put_queue:
> diff --git a/drivers/md/dm.c b/drivers/md/dm.c
> index 54c2a23f4e55c..b163de50f3c6b 100644
> --- a/drivers/md/dm.c
> +++ b/drivers/md/dm.c
> @@ -1693,7 +1693,7 @@ static void dm_split_and_process_bio(struct mapped_device *md,
> */
> WARN_ON_ONCE(!dm_io_flagged(io, DM_IO_WAS_SPLIT));
> io->split_bio = bio_split(bio, io->sectors, GFP_NOIO,
> - &md->queue->bio_split);
> + &md->disk->bio_split);
> bio_chain(io->split_bio, bio);
> trace_block_split(io->split_bio, bio->bi_iter.bi_sector);
> submit_bio_noacct(bio);
> diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
> index d04bdf549efa9..97d3ef8f3f416 100644
> --- a/include/linux/blkdev.h
> +++ b/include/linux/blkdev.h
> @@ -140,6 +140,8 @@ struct gendisk {
> struct request_queue *queue;
> void *private_data;
>
> + struct bio_set bio_split;
> +
> int flags;
> unsigned long state;
> #define GD_NEED_PART_SCAN 0
> @@ -531,7 +533,6 @@ struct request_queue {
>
> struct blk_mq_tag_set *tag_set;
> struct list_head tag_set_list;
> - struct bio_set bio_split;
>
> struct dentry *debugfs_dir;
> struct dentry *sched_debugfs_dir;
Looks good.
Reviewed-by: Damien Le Moal <damien.lemoal@xxxxxxxxxxxxxxxxxx>
--
Damien Le Moal
Western Digital Research
