[Qemu-devel] [PATCH V4 1/3] block: create bdrv_get_backing_file_depth()

[benoit.canet@gmail.com]

From: Benoît Canet <benoit@irqsave.net>

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>
---
 block.c |   13 +++++++++++++
 block.h |    1 +
 2 files changed, 14 insertions(+)

diff --git a/block.c b/block.c
index ce7eb8f..22ebe49 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 c89590d..650d872 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);
-- 
1.7.9.5