Re: [Qemu-block] [PATCH RFC 2/7] block-backend: Introduce blk_root() helper

[Hailiang Zhang]

On 2016/10/25 17:58, Changlong Xie wrote:

I know you need blk->root in the next patch, but we strongly don't
recommend your current solution.  Please refer Kevin's cf2ab8fc

1409 /* XXX Ugly way to get blk->root, but that's a feature, not a
bug. This
1410  * hack makes it obvious that vhdx_write_header() bypasses the
BlockBackend
1411  * here, which it really shouldn't be doing. */
1412 child = QLIST_FIRST(>parents);
1413 assert(!QLIST_NEXT(child, next_parent));

Then you can drop this commit.



OK, got it, I'll drop this patch in next version, thanks.


On 10/20/2016 09:57 PM, zhanghailiang wrote:

With this helper function, we can get the BdrvChild struct
from BlockBackend

Signed-off-by: zhanghailiang 
---
   block/block-backend.c  | 5 +
   include/sysemu/block-backend.h | 1 +
   2 files changed, 6 insertions(+)

diff --git a/block/block-backend.c b/block/block-backend.c
index 1a724a8..66387f0 100644
--- a/block/block-backend.c
+++ b/block/block-backend.c
@@ -389,6 +389,11 @@ BlockDriverState *blk_bs(BlockBackend *blk)
   return blk->root ? blk->root->bs : NULL;
   }

+BdrvChild *blk_root(BlockBackend *blk)
+{
+return blk->root;
+}
+
   static BlockBackend *bdrv_first_blk(BlockDriverState *bs)
   {
   BdrvChild *child;
diff --git a/include/sysemu/block-backend.h b/include/sysemu/block-backend.h
index b07159b..867f9f5 100644
--- a/include/sysemu/block-backend.h
+++ b/include/sysemu/block-backend.h
@@ -99,6 +99,7 @@ void blk_remove_bs(BlockBackend *blk);
   void blk_insert_bs(BlockBackend *blk, BlockDriverState *bs);
   bool bdrv_has_blk(BlockDriverState *bs);
   bool bdrv_is_root_node(BlockDriverState *bs);
+BdrvChild *blk_root(BlockBackend *blk);

   void blk_set_allow_write_beyond_eof(BlockBackend *blk, bool allow);
   void blk_iostatus_enable(BlockBackend *blk);





.

Re: [Qemu-block] [PATCH RFC 2/7] block-backend: Introduce blk_root() helper

[Changlong Xie]

I know you need blk->root in the next patch, but we strongly don't 
recommend your current solution.  Please refer Kevin's cf2ab8fc


1409 /* XXX Ugly way to get blk->root, but that's a feature, not a 
bug. This
1410  * hack makes it obvious that vhdx_write_header() bypasses the 
BlockBackend

1411  * here, which it really shouldn't be doing. */
1412 child = QLIST_FIRST(>parents);
1413 assert(!QLIST_NEXT(child, next_parent));

Then you can drop this commit.

On 10/20/2016 09:57 PM, zhanghailiang wrote:

With this helper function, we can get the BdrvChild struct
from BlockBackend

Signed-off-by: zhanghailiang 
---
  block/block-backend.c  | 5 +
  include/sysemu/block-backend.h | 1 +
  2 files changed, 6 insertions(+)

diff --git a/block/block-backend.c b/block/block-backend.c
index 1a724a8..66387f0 100644
--- a/block/block-backend.c
+++ b/block/block-backend.c
@@ -389,6 +389,11 @@ BlockDriverState *blk_bs(BlockBackend *blk)
  return blk->root ? blk->root->bs : NULL;
  }

+BdrvChild *blk_root(BlockBackend *blk)
+{
+return blk->root;
+}
+
  static BlockBackend *bdrv_first_blk(BlockDriverState *bs)
  {
  BdrvChild *child;
diff --git a/include/sysemu/block-backend.h b/include/sysemu/block-backend.h
index b07159b..867f9f5 100644
--- a/include/sysemu/block-backend.h
+++ b/include/sysemu/block-backend.h
@@ -99,6 +99,7 @@ void blk_remove_bs(BlockBackend *blk);
  void blk_insert_bs(BlockBackend *blk, BlockDriverState *bs);
  bool bdrv_has_blk(BlockDriverState *bs);
  bool bdrv_is_root_node(BlockDriverState *bs);
+BdrvChild *blk_root(BlockBackend *blk);

  void blk_set_allow_write_beyond_eof(BlockBackend *blk, bool allow);
  void blk_iostatus_enable(BlockBackend *blk);

[Qemu-block] [PATCH RFC 2/7] block-backend: Introduce blk_root() helper

[zhanghailiang]

With this helper function, we can get the BdrvChild struct
from BlockBackend

Signed-off-by: zhanghailiang 
---
 block/block-backend.c  | 5 +
 include/sysemu/block-backend.h | 1 +
 2 files changed, 6 insertions(+)

diff --git a/block/block-backend.c b/block/block-backend.c
index 1a724a8..66387f0 100644
--- a/block/block-backend.c
+++ b/block/block-backend.c
@@ -389,6 +389,11 @@ BlockDriverState *blk_bs(BlockBackend *blk)
 return blk->root ? blk->root->bs : NULL;
 }
 
+BdrvChild *blk_root(BlockBackend *blk)
+{
+return blk->root;
+}
+
 static BlockBackend *bdrv_first_blk(BlockDriverState *bs)
 {
 BdrvChild *child;
diff --git a/include/sysemu/block-backend.h b/include/sysemu/block-backend.h
index b07159b..867f9f5 100644
--- a/include/sysemu/block-backend.h
+++ b/include/sysemu/block-backend.h
@@ -99,6 +99,7 @@ void blk_remove_bs(BlockBackend *blk);
 void blk_insert_bs(BlockBackend *blk, BlockDriverState *bs);
 bool bdrv_has_blk(BlockDriverState *bs);
 bool bdrv_is_root_node(BlockDriverState *bs);
+BdrvChild *blk_root(BlockBackend *blk);
 
 void blk_set_allow_write_beyond_eof(BlockBackend *blk, bool allow);
 void blk_iostatus_enable(BlockBackend *blk);
-- 
1.8.3.1