[PATCH 42/43] btrfs: add a leak check for roots

Josef Bacik
2020-01-17T13:49:15Z

Now that we're going to start relying on getting ref counting right for
roots, add a list to track allocated roots and print out any roots that
aren't free'd up at free_fs_info time. Hide this behind
CONFIG_BTRFS_DEBUG because this will just be used for developers to
verify they aren't breaking things.

Signed-off-by: Josef Bacik <josef@toxicpanda.com>
---
fs/btrfs/ctree.h | 5 +++++
fs/btrfs/disk-io.c | 28 ++++++++++++++++++++++++++++
fs/btrfs/disk-io.h | 9 ++++++++-
fs/btrfs/tests/btrfs-tests.c | 1 +
4 files changed, 42 insertions(+), 1 deletion(-)

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 68510af4cacf..6006e10f371f 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -949,6 +949,7 @@ struct btrfs_fs_info {
#ifdef CONFIG_BTRFS_DEBUG
struct kobject *debug_kobj;
struct kobject *discard_debug_kobj;
+ struct list_head alloced_roots;
#endif
};

@@ -1151,6 +1152,10 @@ struct btrfs_root {
#ifdef CONFIG_BTRFS_FS_RUN_SANITY_TESTS
u64 alloc_bytenr;
#endif
+
+#ifdef CONFIG_BTRFS_DEBUG
+ struct list_head leak_list;
+#endif
};

struct btrfs_clone_extent_info {
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 87bad959b1a5..c01cade1a935 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -1202,6 +1202,12 @@ static void __setup_root(struct btrfs_root *root, struct btrfs_fs_info *fs_info,

spin_lock_init(&root->root_item_lock);
btrfs_qgroup_init_swapped_blocks(&root->swapped_blocks);
+#ifdef CONFIG_BTRFS_DEBUG
+ INIT_LIST_HEAD(&root->leak_list);
+ spin_lock(&fs_info->fs_roots_radix_lock);
+ list_add_tail(&root->leak_list, &fs_info->alloced_roots);
+ spin_unlock(&fs_info->fs_roots_radix_lock);
+#endif
}

static struct btrfs_root *btrfs_alloc_root(struct btrfs_fs_info *fs_info,
@@ -1531,6 +1537,24 @@ int btrfs_insert_fs_root(struct btrfs_fs_info *fs_info,
return ret;
}

+void btrfs_check_leaked_roots(struct btrfs_fs_info *fs_info)
+{
+#ifdef CONFIG_BTRFS_DEBUG
+ struct btrfs_root *root;
+
+ while (!list_empty(&fs_info->alloced_roots)) {
+ root = list_first_entry(&fs_info->alloced_roots,
+ struct btrfs_root, leak_list);
+ btrfs_err(fs_info, "leaked root %llu-%llu refcount %d",
+ root->root_key.objectid, root->root_key.offset,
+ refcount_read(&root->refs));
+ while (refcount_read(&root->refs) > 1)
+ btrfs_put_fs_root(root);
+ btrfs_put_fs_root(root);
+ }
+#endif
+}
+
void btrfs_free_fs_info(struct btrfs_fs_info *fs_info)
{
percpu_counter_destroy(&fs_info->dirty_metadata_bytes);
@@ -1551,6 +1575,7 @@ void btrfs_free_fs_info(struct btrfs_fs_info *fs_info)
btrfs_put_fs_root(fs_info->uuid_root);
btrfs_put_fs_root(fs_info->free_space_root);
btrfs_put_fs_root(fs_info->fs_root);
+ btrfs_check_leaked_roots(fs_info);
kfree(fs_info->super_copy);
kfree(fs_info->super_for_commit);
kvfree(fs_info);
@@ -2678,6 +2703,9 @@ void btrfs_init_fs_info(struct btrfs_fs_info *fs_info)
INIT_LIST_HEAD(&fs_info->space_info);
INIT_LIST_HEAD(&fs_info->tree_mod_seq_list);
INIT_LIST_HEAD(&fs_info->unused_bgs);
+#ifdef CONFIG_BTRFS_DEBUG
+ INIT_LIST_HEAD(&fs_info->alloced_roots);
+#endif
extent_map_tree_init(&fs_info->mapping_tree);
btrfs_init_block_rsv(&fs_info->global_block_rsv,
BTRFS_BLOCK_RSV_GLOBAL);
diff --git a/fs/btrfs/disk-io.h b/fs/btrfs/disk-io.h
index 2414d572bc9a..04a29f961527 100644
--- a/fs/btrfs/disk-io.h
+++ b/fs/btrfs/disk-io.h
@@ -39,6 +39,7 @@ static inline u64 btrfs_sb_offset(int mirror)
struct btrfs_device;
struct btrfs_fs_devices;

+void btrfs_check_leaked_roots(struct btrfs_fs_info *fs_info);
void btrfs_init_fs_info(struct btrfs_fs_info *fs_info);
int btrfs_verify_level_key(struct extent_buffer *eb, int level,
struct btrfs_key *first_key, u64 parent_transid);
@@ -101,8 +102,14 @@ static inline void btrfs_put_fs_root(struct btrfs_root *root)
{
if (!root)
return;
- if (refcount_dec_and_test(&root->refs))
+ if (refcount_dec_and_test(&root->refs)) {
+#ifdef CONFIG_BTRFS_DEBUG
+ spin_lock(&root->fs_info->fs_roots_radix_lock);
+ list_del_init(&root->leak_list);
+ spin_unlock(&root->fs_info->fs_roots_radix_lock);
+#endif
kfree(root);
+ }
}

void btrfs_mark_buffer_dirty(struct extent_buffer *buf);
diff --git a/fs/btrfs/tests/btrfs-tests.c b/fs/btrfs/tests/btrfs-tests.c
index 683381a692bc..609abca4fe3a 100644
--- a/fs/btrfs/tests/btrfs-tests.c
+++ b/fs/btrfs/tests/btrfs-tests.c
@@ -193,6 +193,7 @@ void btrfs_free_dummy_fs_info(struct btrfs_fs_info *fs_info)
btrfs_free_fs_roots(fs_info);
cleanup_srcu_struct(&fs_info->subvol_srcu);
kfree(fs_info->super_copy);
+ btrfs_check_leaked_roots(fs_info);
kfree(fs_info->fs_devices);
kfree(fs_info);
}
--
2.24.1