From f198fd1c9aedaae2fa78eb94e236e95ce4f2aedd Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Beno=C3=AEt=20Canet?= <benoit.canet@gmail.com>
Date: Thu, 2 Aug 2012 10:22:47 +0200
Subject: [PATCH] block: create bdrv_get_backing_file_depth()

Create bdrv_get_backing_file_depth() in order to be able to show
in QMP and HMP how many ancestors backing an image a block device
have.

Signed-off-by: Benoit Canet <benoit@irqsave.net>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
---
 block.c | 13 +++++++++++++
 block.h |  1 +
 2 files changed, 14 insertions(+)

diff --git a/block.c b/block.c
index b38940bf85..1206bba84d 100644
--- a/block.c
+++ b/block.c
@@ -2754,6 +2754,19 @@ BlockDriverState *bdrv_find_backing_image(BlockDriverState *bs,
     return NULL;
 }
 
+int bdrv_get_backing_file_depth(BlockDriverState *bs)
+{
+    if (!bs->drv) {
+        return 0;
+    }
+
+    if (!bs->backing_hd) {
+        return 0;
+    }
+
+    return 1 + bdrv_get_backing_file_depth(bs->backing_hd);
+}
+
 #define NB_SUFFIXES 4
 
 char *get_human_readable_size(char *buf, int buf_size, int64_t size)
diff --git a/block.h b/block.h
index c89590df4d..650d872f46 100644
--- a/block.h
+++ b/block.h
@@ -174,6 +174,7 @@ int coroutine_fn bdrv_co_is_allocated_above(BlockDriverState *top,
                                             int nb_sectors, int *pnum);
 BlockDriverState *bdrv_find_backing_image(BlockDriverState *bs,
     const char *backing_file);
+int bdrv_get_backing_file_depth(BlockDriverState *bs);
 int bdrv_truncate(BlockDriverState *bs, int64_t offset);
 int64_t bdrv_getlength(BlockDriverState *bs);
 int64_t bdrv_get_allocated_file_size(BlockDriverState *bs);