From: Josef Bacik <josef@toxicpanda.com>
To: linux-btrfs@vger.kernel.org, kernel-team@fb.com
Subject: [PATCH 06/13] btrfs: add ASSERT()'s for deleting backref cache nodes
Date: Wed, 16 Dec 2020 11:22:10 -0500 [thread overview]
Message-ID: <3fc2e3dd35d339a7251a2ed48af3ba484769002e.1608135557.git.josef@toxicpanda.com> (raw)
In-Reply-To: <cover.1608135557.git.josef@toxicpanda.com>
A weird KASAN problem that Zygo reported could have been easily caught
if we checked for basic things in our backref freeing code. We have two
methods of freeing a backref node
- btrfs_backref_free_node: this just is kfree() essentially.
- btrfs_backref_drop_node: this actually unlinks the node and cleans up
everything and then calls btrfs_backref_free_node().
We should mostly be using btrfs_backref_drop_node(), to make sure the
node is properly unlinked from the backref cache, and only use
btrfs_backref_free_node() when we know the node isn't actually linked to
the backref cache. We made a mistake here and thus got the KASAN splat.
Make this style of issue easier to find by adding some ASSERT()'s to
btrfs_backref_free_node() and adjusting our deletion stuff to properly
init the list so we can rely on list_empty() checks working properly.
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
---
fs/btrfs/backref.h | 9 ++++++---
1 file changed, 6 insertions(+), 3 deletions(-)
diff --git a/fs/btrfs/backref.h b/fs/btrfs/backref.h
index ff705cc564a9..17abde7f794c 100644
--- a/fs/btrfs/backref.h
+++ b/fs/btrfs/backref.h
@@ -296,6 +296,9 @@ static inline void btrfs_backref_free_node(struct btrfs_backref_cache *cache,
struct btrfs_backref_node *node)
{
if (node) {
+ ASSERT(list_empty(&node->list));
+ ASSERT(list_empty(&node->lower));
+ ASSERT(node->eb == NULL);
cache->nr_nodes--;
btrfs_put_root(node->root);
kfree(node);
@@ -340,11 +343,11 @@ static inline void btrfs_backref_drop_node_buffer(
static inline void btrfs_backref_drop_node(struct btrfs_backref_cache *tree,
struct btrfs_backref_node *node)
{
- BUG_ON(!list_empty(&node->upper));
+ ASSERT(list_empty(&node->upper));
btrfs_backref_drop_node_buffer(node);
- list_del(&node->list);
- list_del(&node->lower);
+ list_del_init(&node->list);
+ list_del_init(&node->lower);
if (!RB_EMPTY_NODE(&node->rb_node))
rb_erase(&node->rb_node, &tree->rb_root);
btrfs_backref_free_node(tree, node);
--
2.26.2
next prev parent reply other threads:[~2020-12-16 16:23 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-16 16:22 [PATCH 00/13] Serious fixes for different error paths Josef Bacik
2020-12-16 16:22 ` [PATCH 01/13] btrfs: don't get an EINTR during drop_snapshot for reloc Josef Bacik
2021-01-11 21:56 ` David Sterba
2020-12-16 16:22 ` [PATCH 02/13] btrfs: initialize test inodes location Josef Bacik
2020-12-18 10:30 ` Nikolay Borisov
2020-12-21 16:58 ` David Sterba
2020-12-16 16:22 ` [PATCH 03/13] btrfs: fix reloc root leak with 0 ref reloc roots on recovery Josef Bacik
2020-12-16 16:22 ` [PATCH 04/13] btrfs: splice remaining dirty_bg's onto the transaction dirty bg list Josef Bacik
2021-01-11 22:09 ` David Sterba
2020-12-16 16:22 ` [PATCH 05/13] btrfs: do not WARN_ON() if we can't find the reloc root Josef Bacik
2021-01-11 22:14 ` David Sterba
2020-12-16 16:22 ` Josef Bacik [this message]
2021-01-11 22:18 ` [PATCH 06/13] btrfs: add ASSERT()'s for deleting backref cache nodes David Sterba
2020-12-16 16:22 ` [PATCH 07/13] btrfs: do not double free backref nodes on error Josef Bacik
2020-12-16 16:22 ` [PATCH 08/13] btrfs: abort the transaction if we fail to inc ref in btrfs_copy_root Josef Bacik
2021-01-11 22:20 ` David Sterba
2020-12-16 16:22 ` [PATCH 09/13] btrfs: modify the new_root highest_objectid under a ref count Josef Bacik
2020-12-18 11:18 ` Nikolay Borisov
2020-12-16 16:22 ` [PATCH 10/13] btrfs: fix lockdep splat in btrfs_recover_relocation Josef Bacik
2020-12-16 16:22 ` [PATCH 11/13] btrfs: keep track of the root owner for relocation reads Josef Bacik
2021-01-11 22:23 ` David Sterba
2021-01-14 18:03 ` David Sterba
2020-12-16 16:22 ` [PATCH 12/13] btrfs: do not cleanup upper nodes in btrfs_backref_cleanup_node Josef Bacik
2020-12-16 16:22 ` [PATCH 13/13] btrfs: don't clear ret in btrfs_start_dirty_block_groups Josef Bacik
2021-01-08 16:44 ` [PATCH 00/13] Serious fixes for different error paths David Sterba
2021-01-14 18:20 ` David Sterba
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