[RFC PATCH 7/8] null_blk: add REQ_OP_VERIFY support

[Chaitanya Kulkarni]

From: Chaitanya Kulkarni <kch at nvidia.com>

Add a new module parameter, configfs attribute to configure handling of
the REQ_OP_VERIFY. This is needed for testing newly added REQ_OP_VERIFY
block layer operation.

Signed-off-by: Chaitanya Kulkarni <kch at nvidia.com>
---
 drivers/block/null_blk/main.c     | 25 ++++++++++++++++++++++++-
 drivers/block/null_blk/null_blk.h |  1 +
 2 files changed, 25 insertions(+), 1 deletion(-)

diff --git a/drivers/block/null_blk/main.c b/drivers/block/null_blk/main.c
index d6c821d48090..36a5f5343cee 100644
--- a/drivers/block/null_blk/main.c
+++ b/drivers/block/null_blk/main.c
@@ -216,6 +216,10 @@ static unsigned int g_zone_nr_conv;
 module_param_named(zone_nr_conv, g_zone_nr_conv, uint, 0444);
 MODULE_PARM_DESC(zone_nr_conv, "Number of conventional zones when block device is zoned. Default: 0");
 
+static bool g_verify;
+module_param_named(verify, g_verify, bool, 0444);
+MODULE_PARM_DESC(verify, "Allow REQ_OP_VERIFY processing. Default: false");
+
 static unsigned int g_zone_max_open;
 module_param_named(zone_max_open, g_zone_max_open, uint, 0444);
 MODULE_PARM_DESC(zone_max_open, "Maximum number of open zones when block device is zoned. Default: 0 (no limit)");
@@ -358,6 +362,7 @@ NULLB_DEVICE_ATTR(blocking, bool, NULL);
 NULLB_DEVICE_ATTR(use_per_node_hctx, bool, NULL);
 NULLB_DEVICE_ATTR(memory_backed, bool, NULL);
 NULLB_DEVICE_ATTR(discard, bool, NULL);
+NULLB_DEVICE_ATTR(verify, bool, NULL);
 NULLB_DEVICE_ATTR(mbps, uint, NULL);
 NULLB_DEVICE_ATTR(cache_size, ulong, NULL);
 NULLB_DEVICE_ATTR(zoned, bool, NULL);
@@ -477,6 +482,7 @@ static struct configfs_attribute *nullb_device_attrs[] = {
 	&nullb_device_attr_power,
 	&nullb_device_attr_memory_backed,
 	&nullb_device_attr_discard,
+	&nullb_device_attr_verify,
 	&nullb_device_attr_mbps,
 	&nullb_device_attr_cache_size,
 	&nullb_device_attr_badblocks,
@@ -539,7 +545,7 @@ nullb_group_drop_item(struct config_group *group, struct config_item *item)
 static ssize_t memb_group_features_show(struct config_item *item, char *page)
 {
 	return snprintf(page, PAGE_SIZE,
-			"memory_backed,discard,bandwidth,cache,badblocks,zoned,zone_size,zone_capacity,zone_nr_conv,zone_max_open,zone_max_active,blocksize,max_sectors\n");
+			"memory_backed,discard,verify,bandwidth,cache,badblocks,zoned,zone_size,zone_capacity,zone_nr_conv,zone_max_open,zone_max_active,blocksize,max_sectors\n");
 }
 
 CONFIGFS_ATTR_RO(memb_group_, features);
@@ -601,6 +607,7 @@ static struct nullb_device *null_alloc_dev(void)
 	dev->use_per_node_hctx = g_use_per_node_hctx;
 	dev->zoned = g_zoned;
 	dev->zone_size = g_zone_size;
+	dev->verify = g_verify;
 	dev->zone_capacity = g_zone_capacity;
 	dev->zone_nr_conv = g_zone_nr_conv;
 	dev->zone_max_open = g_zone_max_open;
@@ -1165,6 +1172,9 @@ static int null_handle_rq(struct nullb_cmd *cmd)
 	struct req_iterator iter;
 	struct bio_vec bvec;
 
+	if (req_op(rq) == REQ_OP_VERIFY)
+		return 0;
+
 	spin_lock_irq(&nullb->lock);
 	rq_for_each_segment(bvec, rq, iter) {
 		len = bvec.bv_len;
@@ -1192,6 +1202,9 @@ static int null_handle_bio(struct nullb_cmd *cmd)
 	struct bio_vec bvec;
 	struct bvec_iter iter;
 
+	if (bio_op(bio) == REQ_OP_VERIFY)
+		return 0;
+
 	spin_lock_irq(&nullb->lock);
 	bio_for_each_segment(bvec, bio, iter) {
 		len = bvec.bv_len;
@@ -1609,6 +1622,15 @@ static void null_config_discard(struct nullb *nullb)
 	blk_queue_flag_set(QUEUE_FLAG_DISCARD, nullb->q);
 }
 
+static void null_config_verify(struct nullb *nullb)
+{
+	if (nullb->dev->verify == false)
+		return;
+
+	blk_queue_max_verify_sectors(nullb->q, UINT_MAX >> 9);
+	blk_queue_flag_set(QUEUE_FLAG_VERIFY, nullb->q);
+}
+
 static const struct block_device_operations null_bio_ops = {
 	.owner		= THIS_MODULE,
 	.submit_bio	= null_submit_bio,
@@ -1881,6 +1903,7 @@ static int null_add_dev(struct nullb_device *dev)
 	blk_queue_max_hw_sectors(nullb->q, dev->max_sectors);
 
 	null_config_discard(nullb);
+	null_config_verify(nullb);
 
 	sprintf(nullb->disk_name, "nullb%d", nullb->index);
 
diff --git a/drivers/block/null_blk/null_blk.h b/drivers/block/null_blk/null_blk.h
index 83504f3cc9d6..e6913c099e71 100644
--- a/drivers/block/null_blk/null_blk.h
+++ b/drivers/block/null_blk/null_blk.h
@@ -95,6 +95,7 @@ struct nullb_device {
 	bool power; /* power on/off the device */
 	bool memory_backed; /* if data is stored in memory */
 	bool discard; /* if support discard */
+	bool verify; /* if support verify */
 	bool zoned; /* if device is zoned */
 };
 
-- 
2.22.1