[PATCH v3 2/4] block: expose QUEUE_FLAG_DAX in sysfs

[Mike Snitzer <snitzer-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>]

From: Yigal Korman <yigal-/8YdC2HfS5554TAoqtyWWQ@public.gmane.org>

Provides the ability to identify DAX enabled devices in userspace.

Signed-off-by: Yigal Korman <yigal-/8YdC2HfS5554TAoqtyWWQ@public.gmane.org>
Signed-off-by: Toshi Kani <toshi.kani-ZPxbGqLxI0U@public.gmane.org>
Acked-by: Dan Williams <dan.j.williams-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
Signed-off-by: Mike Snitzer <snitzer-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
---
 block/blk-sysfs.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c
index 9920596..f87a7e7 100644
--- a/block/blk-sysfs.c
+++ b/block/blk-sysfs.c
@@ -379,6 +379,11 @@ static ssize_t queue_wc_store(struct request_queue *q, const char *page,
 	return count;
 }
 
+static ssize_t queue_dax_show(struct request_queue *q, char *page)
+{
+	return queue_var_show(blk_queue_dax(q), page);
+}
+
 static struct queue_sysfs_entry queue_requests_entry = {
 	.attr = {.name = "nr_requests", .mode = S_IRUGO | S_IWUSR },
 	.show = queue_requests_show,
@@ -516,6 +521,11 @@ static struct queue_sysfs_entry queue_wc_entry = {
 	.store = queue_wc_store,
 };
 
+static struct queue_sysfs_entry queue_dax_entry = {
+	.attr = {.name = "dax", .mode = S_IRUGO },
+	.show = queue_dax_show,
+};
+
 static struct attribute *default_attrs[] = {
 	&queue_requests_entry.attr,
 	&queue_ra_entry.attr,
@@ -542,6 +552,7 @@ static struct attribute *default_attrs[] = {
 	&queue_random_entry.attr,
 	&queue_poll_entry.attr,
 	&queue_wc_entry.attr,
+	&queue_dax_entry.attr,
 	NULL,
 };
 
-- 
2.7.4 (Apple Git-66)