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

Signed-off-by: John Garry <[email protected]>
---
 lib/multipath.c | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)

diff --git a/lib/multipath.c b/lib/multipath.c
index 26d9b17998d66..fba1716a165c7 100644
--- a/lib/multipath.c
+++ b/lib/multipath.c
@@ -515,6 +515,27 @@ 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)
 {
@@ -755,6 +776,7 @@ const struct block_device_operations mpath_ops = {
        .submit_bio     = mpath_bdev_submit_bio,
        .ioctl          = mpath_bdev_ioctl,
        .compat_ioctl   = blkdev_compat_ptr_ioctl,
+       .get_unique_id  = mpath_bdev_get_unique_id,
        .report_zones   = mpath_bdev_report_zones,
        .getgeo         = mpath_bdev_getgeo,
        .pr_ops         = &mpath_pr_ops,
-- 
2.43.7


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