[PATCH v3 08/10] null_blk: Support REQ_OP_ZONE_APPEND

[Johannes Thumshirn <johannes.thumshirn@wdc.com>]

From: Damien Le Moal <damien.lemoal@wdc.com>

Support REQ_OP_ZONE_APPEND requests for zone mode null_blk devices.
Use the internally tracked zone write pointer position as the actual
write position, which is returned using the command request __sector
field in the case of an mq device and using the command BIO sector in
the case of a BIO device. Since the write position is used for data copy
in the case of a memory backed device, reverse the order in which
null_handle_zoned() and null_handle_memory_backed() are called to ensure
that null_handle_memory_backed() sees the correct write position for
REQ_OP_ZONE_APPEND operations.

Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>
Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
---
 drivers/block/null_blk_main.c  |  9 +++++---
 drivers/block/null_blk_zoned.c | 38 +++++++++++++++++++++++++++-------
 2 files changed, 37 insertions(+), 10 deletions(-)

diff --git a/drivers/block/null_blk_main.c b/drivers/block/null_blk_main.c
index 3e45e3640c12..5492f1e49eee 100644
--- a/drivers/block/null_blk_main.c
+++ b/drivers/block/null_blk_main.c
@@ -1300,12 +1300,15 @@ static blk_status_t null_handle_cmd(struct nullb_cmd *cmd, sector_t sector,
 			goto out;
 	}
 
+	if (dev->zoned) {
+		cmd->error = null_handle_zoned(cmd, op, sector, nr_sectors);
+		if (cmd->error != BLK_STS_OK)
+			goto out;
+	}
+
 	if (dev->memory_backed)
 		cmd->error = null_handle_memory_backed(cmd, op);
 
-	if (!cmd->error && dev->zoned)
-		cmd->error = null_handle_zoned(cmd, op, sector, nr_sectors);
-
 out:
 	nullb_complete_cmd(cmd);
 	return BLK_STS_OK;
diff --git a/drivers/block/null_blk_zoned.c b/drivers/block/null_blk_zoned.c
index 8259f3212a28..f20be7b91b9f 100644
--- a/drivers/block/null_blk_zoned.c
+++ b/drivers/block/null_blk_zoned.c
@@ -67,13 +67,22 @@ int null_init_zoned_dev(struct nullb_device *dev, struct request_queue *q)
 
 int null_register_zoned_dev(struct nullb *nullb)
 {
+	struct nullb_device *dev = nullb->dev;
 	struct request_queue *q = nullb->q;
 
-	if (queue_is_mq(q))
-		return blk_revalidate_disk_zones(nullb->disk);
+	if (queue_is_mq(q)) {
+		int ret = blk_revalidate_disk_zones(nullb->disk);
+
+		if (ret)
+			return ret;
+	} else {
+		blk_queue_chunk_sectors(q, dev->zone_size_sects);
+		q->nr_zones = blkdev_nr_zones(nullb->disk);
+	}
 
-	blk_queue_chunk_sectors(q, nullb->dev->zone_size_sects);
-	q->nr_zones = blkdev_nr_zones(nullb->disk);
+	blk_queue_max_zone_append_sectors(q,
+			min_t(sector_t, q->limits.max_hw_sectors,
+			      dev->zone_size_sects));
 
 	return 0;
 }
@@ -133,7 +142,7 @@ size_t null_zone_valid_read_len(struct nullb *nullb,
 }
 
 static blk_status_t null_zone_write(struct nullb_cmd *cmd, sector_t sector,
-		     unsigned int nr_sectors)
+				    unsigned int nr_sectors, bool append)
 {
 	struct nullb_device *dev = cmd->nq->dev;
 	unsigned int zno = null_zone_no(dev, sector);
@@ -148,7 +157,20 @@ static blk_status_t null_zone_write(struct nullb_cmd *cmd, sector_t sector,
 	case BLK_ZONE_COND_IMP_OPEN:
 	case BLK_ZONE_COND_EXP_OPEN:
 	case BLK_ZONE_COND_CLOSED:
-		/* Writes must be at the write pointer position */
+		/*
+		 * Regular writes must be at the write pointer position.
+		 * Zone append writes are automatically issued at the write
+		 * pointer and the position returned using the request or BIO
+		 * sector.
+		 */
+		if (append) {
+			sector = zone->wp;
+			if (cmd->bio)
+				cmd->bio->bi_iter.bi_sector = sector;
+			else
+				cmd->rq->__sector = sector;
+		}
+
 		if (sector != zone->wp)
 			return BLK_STS_IOERR;
 
@@ -228,7 +250,9 @@ blk_status_t null_handle_zoned(struct nullb_cmd *cmd, enum req_opf op,
 {
 	switch (op) {
 	case REQ_OP_WRITE:
-		return null_zone_write(cmd, sector, nr_sectors);
+		return null_zone_write(cmd, sector, nr_sectors, false);
+	case REQ_OP_ZONE_APPEND:
+		return null_zone_write(cmd, sector, nr_sectors, true);
 	case REQ_OP_ZONE_RESET:
 	case REQ_OP_ZONE_RESET_ALL:
 	case REQ_OP_ZONE_OPEN:
-- 
2.24.1