[Qemu-devel] [PATCH v3 4/6] block: helper function, to find the base image of a chain

[Jeff Cody <jcody@redhat.com>]

This is a simple helper function, that will return the base image
of a given image chain.

Signed-off-by: Jeff Cody <jcody@redhat.com>
---
 block.c | 16 ++++++++++++++++
 block.h |  1 +
 2 files changed, 17 insertions(+)

diff --git a/block.c b/block.c
index 54209a5..d7a6d14 100644
--- a/block.c
+++ b/block.c
@@ -3117,6 +3117,22 @@ int bdrv_get_backing_file_depth(BlockDriverState *bs)
     return 1 + bdrv_get_backing_file_depth(bs->backing_hd);
 }
 
+BlockDriverState *bdrv_find_base(BlockDriverState *bs)
+{
+    BlockDriverState *curr_bs = NULL;
+
+    if (!bs) {
+        return NULL;
+    }
+
+    curr_bs = bs;
+
+    while (curr_bs->backing_hd) {
+        curr_bs = curr_bs->backing_hd;
+    }
+    return curr_bs;
+}
+
 #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 8c9b424..e9249c4 100644
--- a/block.h
+++ b/block.h
@@ -207,6 +207,7 @@ int bdrv_drop_intermediate(BlockDriverState *active, BlockDriverState *top,
                            BlockDriverState *base);
 BlockDriverState *bdrv_find_overlay(BlockDriverState *active,
                                     BlockDriverState *bs);
+BlockDriverState *bdrv_find_base(BlockDriverState *bs);
 
 
 typedef struct BdrvCheckResult {
-- 
1.7.11.4