[PATCH 6/6] null_blk: add REQ_OP_VERIFY support

[Chaitanya Kulkarni <kch@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@nvidia.com>
---
 drivers/block/null_blk/main.c     | 20 +++++++++++++++++++-
 drivers/block/null_blk/null_blk.h |  1 +
 2 files changed, 20 insertions(+), 1 deletion(-)

diff --git a/drivers/block/null_blk/main.c b/drivers/block/null_blk/main.c
index 6b67088f4ea7..559daac83b94 100644
--- a/drivers/block/null_blk/main.c
+++ b/drivers/block/null_blk/main.c
@@ -77,6 +77,10 @@ enum {
 	NULL_IRQ_TIMER		= 2,
 };
 
+static bool g_verify = true;
+module_param_named(verify, g_verify, bool, 0444);
+MODULE_PARM_DESC(verify, "Allow REQ_OP_VERIFY processing. Default: true");
+
 static bool g_virt_boundary = false;
 module_param_named(virt_boundary, g_virt_boundary, bool, 0444);
 MODULE_PARM_DESC(virt_boundary, "Require a virtual boundary for the device. Default: False");
@@ -400,6 +404,7 @@ 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);
@@ -522,6 +527,7 @@ 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,
@@ -588,7 +594,7 @@ 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,virt_boundary\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,virt_boundary\n");
 }
 
 CONFIGFS_ATTR_RO(memb_group_, features);
@@ -651,6 +657,7 @@ static struct nullb_device *null_alloc_dev(void)
 	dev->hw_queue_depth = g_hw_queue_depth;
 	dev->blocking = g_blocking;
 	dev->use_per_node_hctx = g_use_per_node_hctx;
+	dev->verify = g_verify;
 	dev->zoned = g_zoned;
 	dev->zone_size = g_zone_size;
 	dev->zone_capacity = g_zone_capacity;
@@ -1394,6 +1401,10 @@ blk_status_t null_process_cmd(struct nullb_cmd *cmd,
 			return ret;
 	}
 
+	/* currently implemented as noop */
+	if (op == REQ_OP_VERIFY)
+		return 0;
+
 	if (dev->memory_backed)
 		return null_handle_memory_backed(cmd, op, sector, nr_sectors);
 
@@ -1769,6 +1780,12 @@ static void null_config_discard(struct nullb *nullb)
 	blk_queue_max_discard_sectors(nullb->q, UINT_MAX >> 9);
 }
 
+static void null_config_verify(struct nullb *nullb)
+{
+	blk_queue_max_verify_sectors(nullb->q,
+				     nullb->dev->verify ? UINT_MAX >> 9 : 0);
+}
+
 static const struct block_device_operations null_bio_ops = {
 	.owner		= THIS_MODULE,
 	.submit_bio	= null_submit_bio,
@@ -2059,6 +2076,7 @@ static int null_add_dev(struct nullb_device *dev)
 		blk_queue_virt_boundary(nullb->q, PAGE_SIZE - 1);
 
 	null_config_discard(nullb);
+	null_config_verify(nullb);
 
 	if (config_item_name(&dev->item)) {
 		/* Use configfs dir name as the device name */
diff --git a/drivers/block/null_blk/null_blk.h b/drivers/block/null_blk/null_blk.h
index 8359b43842f2..2a1df1bc8165 100644
--- a/drivers/block/null_blk/null_blk.h
+++ b/drivers/block/null_blk/null_blk.h
@@ -111,6 +111,7 @@ 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 */
 	bool virt_boundary; /* virtual boundary on/off for the device */
 };
-- 
2.29.0