[PATCH v8 9/9] null_blk: add support for copy offload

Anuj Gupta
2023-03-29T08:16:44Z

From: Nitesh Shetty <nj.shetty@samsung.com>

Implementaion is based on existing read and write infrastructure.

Suggested-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>
Signed-off-by: Anuj Gupta <anuj20.g@samsung.com>
Signed-off-by: Nitesh Shetty <nj.shetty@samsung.com>
Signed-off-by: Vincent Fu <vincent.fu@samsung.com>
---
drivers/block/null_blk/main.c | 94 +++++++++++++++++++++++++++++++
drivers/block/null_blk/null_blk.h | 7 +++
2 files changed, 101 insertions(+)

diff --git a/drivers/block/null_blk/main.c b/drivers/block/null_blk/main.c
index 9e6b032c8ecc..84c5fbcd67a5 100644
--- a/drivers/block/null_blk/main.c
+++ b/drivers/block/null_blk/main.c
@@ -1257,6 +1257,81 @@ static int null_transfer(struct nullb *nullb, struct page *page,
return err;
}

+static inline int nullb_setup_copy_read(struct nullb *nullb,
+ struct bio *bio)
+{
+ struct nullb_copy_token *token = bvec_kmap_local(&bio->bi_io_vec[0]);
+
+ memcpy(token->subsys, "nullb", 5);
+ token->sector_in = bio->bi_iter.bi_sector;
+ token->nullb = nullb;
+ token->sectors = bio->bi_iter.bi_size >> SECTOR_SHIFT;
+
+ return 0;
+}
+
+static inline int nullb_setup_copy_write(struct nullb *nullb,
+ struct bio *bio, bool is_fua)
+{
+ struct nullb_copy_token *token = bvec_kmap_local(&bio->bi_io_vec[0]);
+ sector_t sector_in, sector_out;
+ void *in, *out;
+ size_t rem, temp;
+ unsigned long offset_in, offset_out;
+ struct nullb_page *t_page_in, *t_page_out;
+ int ret = -EIO;
+
+ if (unlikely(memcmp(token->subsys, "nullb", 5)))
+ return -EOPNOTSUPP;
+ if (unlikely(token->nullb != nullb))
+ return -EOPNOTSUPP;
+ if (WARN_ON(token->sectors != bio->bi_iter.bi_size >> SECTOR_SHIFT))
+ return -EOPNOTSUPP;
+
+ sector_in = token->sector_in;
+ sector_out = bio->bi_iter.bi_sector;
+ rem = token->sectors << SECTOR_SHIFT;
+
+ spin_lock_irq(&nullb->lock);
+ while (rem > 0) {
+ temp = min_t(size_t, nullb->dev->blocksize, rem);
+ offset_in = (sector_in & SECTOR_MASK) << SECTOR_SHIFT;
+ offset_out = (sector_out & SECTOR_MASK) << SECTOR_SHIFT;
+
+ if (null_cache_active(nullb) && !is_fua)
+ null_make_cache_space(nullb, PAGE_SIZE);
+
+ t_page_in = null_lookup_page(nullb, sector_in, false,
+ !null_cache_active(nullb));
+ if (!t_page_in)
+ goto err;
+ t_page_out = null_insert_page(nullb, sector_out,
+ !null_cache_active(nullb) || is_fua);
+ if (!t_page_out)
+ goto err;
+
+ in = kmap_local_page(t_page_in->page);
+ out = kmap_local_page(t_page_out->page);
+
+ memcpy(out + offset_out, in + offset_in, temp);
+ kunmap_local(out);
+ kunmap_local(in);
+ __set_bit(sector_out & SECTOR_MASK, t_page_out->bitmap);
+
+ if (is_fua)
+ null_free_sector(nullb, sector_out, true);
+
+ rem -= temp;
+ sector_in += temp >> SECTOR_SHIFT;
+ sector_out += temp >> SECTOR_SHIFT;
+ }
+
+ ret = 0;
+err:
+ spin_unlock_irq(&nullb->lock);
+ return ret;
+}
+
static int null_handle_rq(struct nullb_cmd *cmd)
{
struct request *rq = cmd->rq;
@@ -1267,6 +1342,14 @@ static int null_handle_rq(struct nullb_cmd *cmd)
struct req_iterator iter;
struct bio_vec bvec;

+ if (rq->cmd_flags & REQ_COPY) {
+ if (op_is_write(req_op(rq)))
+ return nullb_setup_copy_write(nullb, rq->bio,
+ rq->cmd_flags & REQ_FUA);
+ else
+ return nullb_setup_copy_read(nullb, rq->bio);
+ }
+
spin_lock_irq(&nullb->lock);
rq_for_each_segment(bvec, rq, iter) {
len = bvec.bv_len;
@@ -1294,6 +1377,14 @@ static int null_handle_bio(struct nullb_cmd *cmd)
struct bio_vec bvec;
struct bvec_iter iter;

+ if (bio->bi_opf & REQ_COPY) {
+ if (op_is_write(bio_op(bio)))
+ return nullb_setup_copy_write(nullb, bio,
+ bio->bi_opf & REQ_FUA);
+ else
+ return nullb_setup_copy_read(nullb, bio);
+ }
+
spin_lock_irq(&nullb->lock);
bio_for_each_segment(bvec, bio, iter) {
len = bvec.bv_len;
@@ -2146,6 +2237,9 @@ static int null_add_dev(struct nullb_device *dev)
list_add_tail(&nullb->list, &nullb_list);
mutex_unlock(&lock);

+ blk_queue_max_copy_sectors_hw(nullb->disk->queue, 1024);
+ blk_queue_flag_set(QUEUE_FLAG_COPY, nullb->disk->queue);
+
pr_info("disk %s created\n", nullb->disk_name);

return 0;
diff --git a/drivers/block/null_blk/null_blk.h b/drivers/block/null_blk/null_blk.h
index eb5972c50be8..94e524e7306a 100644
--- a/drivers/block/null_blk/null_blk.h
+++ b/drivers/block/null_blk/null_blk.h
@@ -67,6 +67,13 @@ enum {
NULL_Q_MQ = 2,
};

+struct nullb_copy_token {
+ char subsys[5];
+ struct nullb *nullb;
+ u64 sector_in;
+ u64 sectors;
+};
+
struct nullb_device {
struct nullb *nullb;
struct config_item item;
--
2.35.1.500.gb896f729e2