[PATCH v6 10/27] libmultipath: Add mpath_bdev_get_unique_id()

[John Garry]

From: John Garry <john.garry@xxxxxxxxx>

Add mpath_bdev_get_unique_id() as a multipath block device .get_unique_id
handler.

Signed-off-by: John Garry <john.g.garry@xxxxxxxxxx>
---
 lib/multipath.c | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)

diff --git a/lib/multipath.c b/lib/multipath.c
index 2017c4d0a210c..66b3338cf8389 100644
--- a/lib/multipath.c
+++ b/lib/multipath.c
@@ -454,6 +454,27 @@ static void mpath_bdev_release(struct gendisk *disk)
 	mpath_put_head(mpath_head);
 }
 
+static int mpath_bdev_get_unique_id(struct gendisk *disk, u8 id[16],
+    enum blk_unique_id type)
+{
+	struct mpath_head *mpath_head = mpath_gendisk_to_head(disk);
+	int srcu_idx, ret = -EWOULDBLOCK;
+	struct mpath_device *mpath_device;
+
+	srcu_idx = srcu_read_lock(&mpath_head->srcu);
+	mpath_device = mpath_find_path(mpath_head);
+	if (mpath_device) {
+		if (mpath_device->disk->fops->get_unique_id)
+			ret = mpath_device->disk->fops->get_unique_id(
+					mpath_device->disk, id, type);
+		else
+			ret = 0; /* referencing __dm_get_unique_id() */
+	}
+	srcu_read_unlock(&mpath_head->srcu, srcu_idx);
+
+	return ret;
+}
+
 static int mpath_bdev_ioctl(struct block_device *bdev, blk_mode_t mode,
 		    unsigned int cmd, unsigned long arg)
 {
@@ -521,6 +542,7 @@ const struct block_device_operations mpath_ops = {
 	 * avoid their custom compat_ioctl implementation.
 	 */
 	.compat_ioctl	= blkdev_compat_ptr_ioctl,
+	.get_unique_id	= mpath_bdev_get_unique_id,
 	.getgeo		= mpath_bdev_getgeo,
 };
 EXPORT_SYMBOL_GPL(mpath_ops);
-- 
2.43.7