[PATCH] block: don't show io_timeout if driver has no timeout handler

[Weiping Zhang <zhangweiping@xxxxxxxxxxxxxx>]

If the low level driver has no timerout handler, the
/sys/block/<disk>/queue/io_timeout will not be displayed.

Signed-off-by: Weiping Zhang <zhangweiping@xxxxxxxxxxxxxx>
---
 block/blk-sysfs.c | 33 +++++++++++++++++++++++++++++++--
 1 file changed, 31 insertions(+), 2 deletions(-)

diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c
index 0619c8922893..e9ee81c43d36 100644
--- a/block/blk-sysfs.c
+++ b/block/blk-sysfs.c
@@ -726,7 +726,7 @@ static struct queue_sysfs_entry throtl_sample_time_entry = {
 };
 #endif
 
-static struct attribute *default_attrs[] = {
+static struct attribute *queue_attrs[] = {
 	&queue_requests_entry.attr,
 	&queue_ra_entry.attr,
 	&queue_max_hw_sectors_entry.attr,
@@ -768,6 +768,26 @@ static struct attribute *default_attrs[] = {
 	NULL,
 };
 
+static umode_t queue_attr_visible(struct kobject *kobj, struct attribute *attr,
+				int n)
+{
+	struct request_queue *q =
+		container_of(kobj, struct request_queue, kobj);
+
+	if (attr == &queue_io_timeout_entry.attr) {
+		if (!q->mq_ops || !q->mq_ops->timeout)
+			return 0;
+	}
+
+	return attr->mode;
+}
+
+static struct attribute_group queue_attr_group = {
+	.attrs = queue_attrs,
+	.is_visible = queue_attr_visible,
+};
+
+
 #define to_queue(atr) container_of((atr), struct queue_sysfs_entry, attr)
 
 static ssize_t
@@ -893,7 +913,6 @@ static const struct sysfs_ops queue_sysfs_ops = {
 
 struct kobj_type blk_queue_ktype = {
 	.sysfs_ops	= &queue_sysfs_ops,
-	.default_attrs	= default_attrs,
 	.release	= blk_release_queue,
 };
 
@@ -942,6 +961,14 @@ int blk_register_queue(struct gendisk *disk)
 		goto unlock;
 	}
 
+	ret = sysfs_create_group(&q->kobj, &queue_attr_group);
+	if (ret) {
+		kobject_del(&q->kobj);
+		blk_trace_remove_sysfs(dev);
+		kobject_put(&dev->kobj);
+		goto unlock;
+	}
+
 	if (queue_is_mq(q)) {
 		__blk_mq_register_dev(dev, q);
 		blk_mq_debugfs_register(q);
@@ -958,6 +985,7 @@ int blk_register_queue(struct gendisk *disk)
 		if (ret) {
 			mutex_unlock(&q->sysfs_lock);
 			kobject_uevent(&q->kobj, KOBJ_REMOVE);
+			sysfs_remove_group(&q->kobj, &queue_attr_group);
 			kobject_del(&q->kobj);
 			blk_trace_remove_sysfs(dev);
 			kobject_put(&dev->kobj);
@@ -1006,6 +1034,7 @@ void blk_unregister_queue(struct gendisk *disk)
 		blk_mq_unregister_dev(disk_to_dev(disk), q);
 	mutex_unlock(&q->sysfs_lock);
 
+	sysfs_remove_group(&q->kobj, &queue_attr_group);
 	kobject_uevent(&q->kobj, KOBJ_REMOVE);
 	kobject_del(&q->kobj);
 	blk_trace_remove_sysfs(disk_to_dev(disk));
-- 
2.14.1