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

[Anuj Gupta <anuj20.g@xxxxxxxxxxx>]

From: Nitesh Shetty <nj.shetty@xxxxxxxxxxx>

Implementaion is based on existing read and write infrastructure.

Suggested-by: Damien Le Moal <damien.lemoal@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Anuj Gupta <anuj20.g@xxxxxxxxxxx>
Signed-off-by: Nitesh Shetty <nj.shetty@xxxxxxxxxxx>
Signed-off-by: Vincent Fu <vincent.fu@xxxxxxxxxxx>
---
 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