[libnbd PATCH] info: Add support for new 'qemu-nbd -A' qemu:allocation-depth

[Eric Blake]

A rather trivial decoding; we may enhance it further if qemu extends
things to give an integer depth alongside its tri-state encoding.
---

I'll wait to push this to libnbd until the counterpart qemu patches
land upstream, although it looks like I've got positive review.

 info/nbdinfo.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/info/nbdinfo.c b/info/nbdinfo.c
index 24ec129..1afdf98 100644
--- a/info/nbdinfo.c
+++ b/info/nbdinfo.c
@@ -780,6 +780,13 @@ extent_description (const char *metacontext, uint32_t type)
     case 1: return "dirty";
     }
   }
+  else if (strcmp (metacontext, "qemu:allocation-depth") == 0) {
+    switch (type & 3) {
+    case 0: return "unallocated";
+    case 1: return "local";
+    case 2: return "backing";
+    }
+  }

   return NULL;   /* Don't know - description field will be omitted. */
 }
-- 
2.29.0.rc1