block: expose QUEUE_FLAG_DAX in sysfs

Provides the ability to identify DAX enabled devices in userspace.

Signed-off-by: Yigal Korman <yigal@plexistor.com>
Signed-off-by: Toshi Kani <toshi.kani@hpe.com>
Acked-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Jens Axboe <axboe@fb.com>

1 files changed, 11 insertions, 0 deletions

diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c
index 99205965f559..f87a7e747d36 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,
 };