[PATCH] btrfs: fix qgroup record leaks when using simple quotas

[fdmanana@kernel.org]

From: Filipe Manana <fdmanana@suse.com>

When using simple quotas we are not supposed to allocate qgroup records
when adding delayed references. However we allocate them if either mode
of quotas is enabled (the new simple one or the old one), but then we
never free them because running the accounting, which frees the records,
is only run when using the old quotas (at btrfs_qgroup_account_extents()),
resulting in a memory leak of the records allocated when adding delayed
references.

Fix this by allocating the records only if the old quotas mode is enabled.
Also fix btrfs_qgroup_trace_extent_nolock() to return 1 if the old quotas
mode is not enabled - meaning the caller has to free the record.

Fixes: 182940f4f4db ("btrfs: qgroup: add new quota mode for simple quotas")
Reported-by: syzbot+d3ddc6dcc6386dea398b@syzkaller.appspotmail.com
Link: https://lore.kernel.org/linux-btrfs/00000000000004769106097f9a34@google.com/
Signed-off-by: Filipe Manana <fdmanana@suse.com>
---
 fs/btrfs/delayed-ref.c | 4 ++--
 fs/btrfs/qgroup.c      | 2 +-
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/fs/btrfs/delayed-ref.c b/fs/btrfs/delayed-ref.c
index 9223934d95f4..891ea2fa263c 100644
--- a/fs/btrfs/delayed-ref.c
+++ b/fs/btrfs/delayed-ref.c
@@ -1041,7 +1041,7 @@ int btrfs_add_delayed_tree_ref(struct btrfs_trans_handle *trans,
 		return -ENOMEM;
 	}
 
-	if (btrfs_qgroup_enabled(fs_info) && !generic_ref->skip_qgroup) {
+	if (btrfs_qgroup_full_accounting(fs_info) && !generic_ref->skip_qgroup) {
 		record = kzalloc(sizeof(*record), GFP_NOFS);
 		if (!record) {
 			kmem_cache_free(btrfs_delayed_tree_ref_cachep, ref);
@@ -1144,7 +1144,7 @@ int btrfs_add_delayed_data_ref(struct btrfs_trans_handle *trans,
 		return -ENOMEM;
 	}
 
-	if (btrfs_qgroup_enabled(fs_info) && !generic_ref->skip_qgroup) {
+	if (btrfs_qgroup_full_accounting(fs_info) && !generic_ref->skip_qgroup) {
 		record = kzalloc(sizeof(*record), GFP_NOFS);
 		if (!record) {
 			kmem_cache_free(btrfs_delayed_data_ref_cachep, ref);
diff --git a/fs/btrfs/qgroup.c b/fs/btrfs/qgroup.c
index e48eba7e9379..ce446d9d7f23 100644
--- a/fs/btrfs/qgroup.c
+++ b/fs/btrfs/qgroup.c
@@ -1888,7 +1888,7 @@ int btrfs_qgroup_trace_extent_nolock(struct btrfs_fs_info *fs_info,
 	u64 bytenr = record->bytenr;
 
 	if (!btrfs_qgroup_full_accounting(fs_info))
-		return 0;
+		return 1;
 
 	lockdep_assert_held(&delayed_refs->lock);
 	trace_btrfs_qgroup_trace_extent(fs_info, record);
-- 
2.40.1