From: Max Reitz <mreitz@redhat.com>
Date: Thu, 18 Jun 2020 15:39:28 +0000 (+0200)
Subject: block: Use bdrv_cow_child() in bdrv_co_truncate()
X-Git-Tag: v5.2.0-rc0~123^2~35
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=23b93525a2f30915f6c8418eb23db6912a3b5811;p=thirdparty%2Fqemu.git

block: Use bdrv_cow_child() in bdrv_co_truncate()

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 <mreitz@redhat.com>
Reviewed-by: Andrey Shinkevich <andrey.shinkevich@virtuozzo.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
---

diff --git a/block/io.c b/block/io.c
index 4ee8fe5465e..6f9402117e5 100644
--- a/block/io.c
+++ b/block/io.c
@@ -3310,7 +3310,7 @@ 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;
@@ -3363,6 +3363,7 @@ 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
@@ -3374,10 +3375,10 @@ 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");