diff mbox

[v7,for,2.1,1/4] block: add helper function to determine if a BDS is in a chain

Message ID 0c52400d7448e0c27bdb07ed493c39c7f77b3516.1403723847.git.jcody@redhat.com
State New
Headers show

Commit Message

Jeff Cody June 25, 2014, 7:40 p.m. UTC 
This is a small helper function, to determine if 'base' is in the
chain of BlockDriverState 'top'.  It returns true if it is in the chain,
and false otherwise.

If either argument is NULL, it will also return false.

Reviewed-by: Benoit Canet <benoit@irqsave.net>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Jeff Cody <jcody@redhat.com>
---
 block.c               | 11 +++++++++++
 include/block/block.h |  1 +
 2 files changed, 12 insertions(+)

Comments

Kevin Wolf June 30, 2014, 2:55 p.m. UTC | #1 
Am 25.06.2014 um 21:40 hat Jeff Cody geschrieben:
> This is a small helper function, to determine if 'base' is in the
> chain of BlockDriverState 'top'.  It returns true if it is in the chain,
> and false otherwise.
> 
> If either argument is NULL, it will also return false.
> 
> Reviewed-by: Benoit Canet <benoit@irqsave.net>
> Reviewed-by: Eric Blake <eblake@redhat.com>
> Signed-off-by: Jeff Cody <jcody@redhat.com>

Reviewed-by: Kevin Wolf <kwolf@redhat.com>
diff mbox

Patch

diff --git a/block.c b/block.c
index a91809c..84ddb46 100644
--- a/block.c
+++ b/block.c
@@ -3781,6 +3781,17 @@  BlockDriverState *bdrv_lookup_bs(const char *device,
     return NULL;
 }
 
+/* If 'base' is in the same chain as 'top', return true. Otherwise,
+ * return false.  If either argument is NULL, return false. */
+bool bdrv_chain_contains(BlockDriverState *top, BlockDriverState *base)
+{
+    while (top && top != base) {
+        top = top->backing_hd;
+    }
+
+    return top != NULL;
+}
+
 BlockDriverState *bdrv_next(BlockDriverState *bs)
 {
     if (!bs) {
diff --git a/include/block/block.h b/include/block/block.h
index d0baf4f..1055990 100644
--- a/include/block/block.h
+++ b/include/block/block.h
@@ -399,6 +399,7 @@  BlockDeviceInfoList *bdrv_named_nodes_list(void);
 BlockDriverState *bdrv_lookup_bs(const char *device,
                                  const char *node_name,
                                  Error **errp);
+bool bdrv_chain_contains(BlockDriverState *top, BlockDriverState *base);
 BlockDriverState *bdrv_next(BlockDriverState *bs);
 void bdrv_iterate(void (*it)(void *opaque, BlockDriverState *bs),
                   void *opaque);