Re: [PATCH v7 16/47] block: Use bdrv_cow_child() in bdrv_co_truncate()

[Andrey Shinkevich]

On 25.06.2020 18:21, Max Reitz wrote:

The condition modified here is not about potentially filtered children,
but only about COW sources (i.e. traditional backing files).

Signed-off-by: Max Reitz 
---
  block/io.c | 7 ---
  1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/block/io.c b/block/io.c
index dc9891d6ce..097a3861d8 100644
--- a/block/io.c
+++ b/block/io.c
@@ -3308,7 +3308,7 @@ int coroutine_fn bdrv_co_truncate(BdrvChild *child, 
int64_t offset, bool exact,
Error **errp)
  {
  BlockDriverState *bs = child->bs;
-BdrvChild *filtered;
+BdrvChild *filtered, *backing;
  BlockDriver *drv = bs->drv;
  BdrvTrackedRequest req;
  int64_t old_size, new_bytes;
@@ -3361,6 +3361,7 @@ int coroutine_fn bdrv_co_truncate(BdrvChild *child, 
int64_t offset, bool exact,
  }
  
  filtered = bdrv_filter_child(bs);

+backing = bdrv_cow_child(bs);
  
  /*

   * If the image has a backing file that is large enough that it would
@@ -3372,10 +3373,10 @@ int coroutine_fn bdrv_co_truncate(BdrvChild *child, 
int64_t offset, bool exact,
   * backing file, taking care of keeping things consistent with that 
backing
   * file is the user's responsibility.
   */
-if (new_bytes && bs->backing) {
+if (new_bytes && backing) {
  int64_t backing_len;
  
-backing_len = bdrv_getlength(backing_bs(bs));

+backing_len = bdrv_getlength(backing->bs);
  if (backing_len < 0) {
  ret = backing_len;
  error_setg_errno(errp, -ret, "Could not get backing file size");

Reviewed-by: Andrey Shinkevich 

[PATCH v7 16/47] block: Use bdrv_cow_child() in bdrv_co_truncate()

[Max Reitz]

The condition modified here is not about potentially filtered children,
but only about COW sources (i.e. traditional backing files).

Signed-off-by: Max Reitz 
---
 block/io.c | 7 ---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/block/io.c b/block/io.c
index dc9891d6ce..097a3861d8 100644
--- a/block/io.c
+++ b/block/io.c
@@ -3308,7 +3308,7 @@ int coroutine_fn bdrv_co_truncate(BdrvChild *child, 
int64_t offset, bool exact,
   Error **errp)
 {
 BlockDriverState *bs = child->bs;
-BdrvChild *filtered;
+BdrvChild *filtered, *backing;
 BlockDriver *drv = bs->drv;
 BdrvTrackedRequest req;
 int64_t old_size, new_bytes;
@@ -3361,6 +3361,7 @@ int coroutine_fn bdrv_co_truncate(BdrvChild *child, 
int64_t offset, bool exact,
 }
 
 filtered = bdrv_filter_child(bs);
+backing = bdrv_cow_child(bs);
 
 /*
  * If the image has a backing file that is large enough that it would
@@ -3372,10 +3373,10 @@ int coroutine_fn bdrv_co_truncate(BdrvChild *child, 
int64_t offset, bool exact,
  * backing file, taking care of keeping things consistent with that backing
  * file is the user's responsibility.
  */
-if (new_bytes && bs->backing) {
+if (new_bytes && backing) {
 int64_t backing_len;
 
-backing_len = bdrv_getlength(backing_bs(bs));
+backing_len = bdrv_getlength(backing->bs);
 if (backing_len < 0) {
 ret = backing_len;
 error_setg_errno(errp, -ret, "Could not get backing file size");
-- 
2.26.2