[PATCH 7/8] null_blk: add support for configfs write_zeroes

[Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>]

This patch adds a new configfs parameter to enable REQ_OP_WRITE_ZEROES
feature for null_blk similar to REQ_OP_DISCARD when device is memory
backed.

Signed-off-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
---
 drivers/block/null_blk_main.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/block/null_blk_main.c b/drivers/block/null_blk_main.c
index 30cb90553167..c734ddaa697f 100644
--- a/drivers/block/null_blk_main.c
+++ b/drivers/block/null_blk_main.c
@@ -308,6 +308,7 @@ NULLB_DEVICE_ATTR(blocking, bool);
 NULLB_DEVICE_ATTR(use_per_node_hctx, bool);
 NULLB_DEVICE_ATTR(memory_backed, bool);
 NULLB_DEVICE_ATTR(discard, bool);
+NULLB_DEVICE_ATTR(write_zeroes, bool);
 NULLB_DEVICE_ATTR(mbps, uint);
 NULLB_DEVICE_ATTR(cache_size, ulong);
 NULLB_DEVICE_ATTR(zoned, bool);
@@ -423,6 +424,7 @@ static struct configfs_attribute *nullb_device_attrs[] = {
 	&nullb_device_attr_power,
 	&nullb_device_attr_memory_backed,
 	&nullb_device_attr_discard,
+	&nullb_device_attr_write_zeroes,
 	&nullb_device_attr_mbps,
 	&nullb_device_attr_cache_size,
 	&nullb_device_attr_badblocks,
@@ -481,7 +483,7 @@ 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\n");
+	return snprintf(page, PAGE_SIZE, "memory_backed,discard,write_zeroes,bandwidth,cache,badblocks,zoned,zone_size\n");
 }
 
 CONFIGFS_ATTR_RO(memb_group_, features);
-- 
2.17.0