[PATCH v2] btrfs: tests: Fix memory leak in btrfs_test_qgroups()

[PATCH v2] btrfs: tests: Fix memory leak in btrfs_test_qgroups()

[Zilin Guan]

If btrfs_insert_fs_root() fails, the tmp_root allocated by
btrfs_alloc_dummy_root() is leaked because its initial reference count
is not decremented.

Fix this by calling btrfs_put_root() unconditionally after
btrfs_insert_fs_root(). This ensures the local reference is always
dropped.

Also fix a copy-paste error in the error message where the subvolume
root insertion failure was incorrectly logged as "fs root".

Co-developed-by: Jianhao Xu <jianhao.xu@seu.edu.cn>
Signed-off-by: Jianhao Xu <jianhao.xu@seu.edu.cn>
Signed-off-by: Zilin Guan <zilin@seu.edu.cn>
---
Changes in v2:
- Reword commit message to be more concise.
- Fix copy-paste error in the error message.
- Add Co-developed-by and Signed-off-by tag.
---
 fs/btrfs/tests/qgroup-tests.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/fs/btrfs/tests/qgroup-tests.c b/fs/btrfs/tests/qgroup-tests.c
index e9124605974b..0fcc31beeffe 100644
--- a/fs/btrfs/tests/qgroup-tests.c
+++ b/fs/btrfs/tests/qgroup-tests.c
@@ -517,11 +517,11 @@ int btrfs_test_qgroups(u32 sectorsize, u32 nodesize)
 	tmp_root->root_key.objectid = BTRFS_FS_TREE_OBJECTID;
 	root->fs_info->fs_root = tmp_root;
 	ret = btrfs_insert_fs_root(root->fs_info, tmp_root);
+	btrfs_put_root(tmp_root);
 	if (ret) {
 		test_err("couldn't insert fs root %d", ret);
 		goto out;
 	}
-	btrfs_put_root(tmp_root);
 
 	tmp_root = btrfs_alloc_dummy_root(fs_info);
 	if (IS_ERR(tmp_root)) {
@@ -532,11 +532,11 @@ int btrfs_test_qgroups(u32 sectorsize, u32 nodesize)
 
 	tmp_root->root_key.objectid = BTRFS_FIRST_FREE_OBJECTID;
 	ret = btrfs_insert_fs_root(root->fs_info, tmp_root);
+	btrfs_put_root(tmp_root);
 	if (ret) {
-		test_err("couldn't insert fs root %d", ret);
+		test_err("couldn't insert subvolume root %d", ret);
 		goto out;
 	}
-	btrfs_put_root(tmp_root);
 
 	test_msg("running qgroup tests");
 	ret = test_no_shared_qgroup(root, sectorsize, nodesize);
-- 
2.34.1

Re: [PATCH v2] btrfs: tests: Fix memory leak in btrfs_test_qgroups()

[David Sterba]

On Fri, Dec 26, 2025 at 11:30:22AM +0000, Zilin Guan wrote:
> If btrfs_insert_fs_root() fails, the tmp_root allocated by
> btrfs_alloc_dummy_root() is leaked because its initial reference count
> is not decremented.
> 
> Fix this by calling btrfs_put_root() unconditionally after
> btrfs_insert_fs_root(). This ensures the local reference is always
> dropped.
> 
> Also fix a copy-paste error in the error message where the subvolume
> root insertion failure was incorrectly logged as "fs root".
> 
> Co-developed-by: Jianhao Xu <jianhao.xu@seu.edu.cn>
> Signed-off-by: Jianhao Xu <jianhao.xu@seu.edu.cn>
> Signed-off-by: Zilin Guan <zilin@seu.edu.cn>
> ---
> Changes in v2:
> - Reword commit message to be more concise.
> - Fix copy-paste error in the error message.
> - Add Co-developed-by and Signed-off-by tag.

Added to for-next, thanks.