btrfs: add a leak check for roots

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 freed 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.

Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 8c1a8f2..ffd99c3 100644 (file)
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -947,6 +947,7 @@ struct btrfs_fs_info {
 #ifdef CONFIG_BTRFS_DEBUG
        struct kobject *debug_kobj;
        struct kobject *discard_debug_kobj;
+       struct list_head allocated_roots;
 #endif
 };
 
@@ -1149,6 +1150,10 @@ 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 3e4df0c..c2838a4 100644 (file)
--- 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->allocated_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->allocated_roots)) {
+               root = list_first_entry(&fs_info->allocated_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);
@@ -2677,6 +2702,9 @@ 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->allocated_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 2414d57..04a29f9 100644 (file)
--- 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 683381a..609abca 100644 (file)
--- 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);
 }