btrfs: assert proper locks are held at tree_insert_offset()

There are multiple code paths leading to tree_insert_offset(), and each
path takes the necessary locks before tree_insert_offset() is called,
since they do other things that require those locks to be held. This makes
it easy to miss the locking somewhere, so make tree_insert_offset() assert
that the required locks are being held by the calling task.

Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/free-space-cache.c b/fs/btrfs/free-space-cache.c
index ced874a..be45be6 100644 (file)
--- a/fs/btrfs/free-space-cache.c
+++ b/fs/btrfs/free-space-cache.c
@@ -1598,12 +1598,25 @@ static inline u64 offset_to_bitmap(struct btrfs_free_space_ctl *ctl,
        return bitmap_start;
 }
 
-static int tree_insert_offset(struct rb_root *root,
+static int tree_insert_offset(struct btrfs_free_space_ctl *ctl,
+                             struct btrfs_free_cluster *cluster,
                              struct btrfs_free_space *new_entry)
 {
-       struct rb_node **p = &root->rb_node;
+       struct rb_root *root;
+       struct rb_node **p;
        struct rb_node *parent = NULL;
 
+       lockdep_assert_held(&ctl->tree_lock);
+
+       if (cluster) {
+               lockdep_assert_held(&cluster->lock);
+               root = &cluster->root;
+       } else {
+               root = &ctl->free_space_offset;
+       }
+
+       p = &root->rb_node;
+
        while (*p) {
                struct btrfs_free_space *info;
 
@@ -1836,7 +1849,7 @@ static int link_free_space(struct btrfs_free_space_ctl *ctl,
        int ret = 0;
 
        ASSERT(info->bytes || info->bitmap);
-       ret = tree_insert_offset(&ctl->free_space_offset, info);
+       ret = tree_insert_offset(ctl, NULL, info);
        if (ret)
                return ret;
 
@@ -3013,7 +3026,7 @@ static void __btrfs_return_cluster_to_free_space(
                                        entry->bytes;
                        }
                }
-               tree_insert_offset(&ctl->free_space_offset, entry);
+               tree_insert_offset(ctl, NULL, entry);
                rb_add_cached(&entry->bytes_index, &ctl->free_space_bytes,
                              entry_less);
        }
@@ -3387,7 +3400,7 @@ again:
         */
        RB_CLEAR_NODE(&entry->bytes_index);
 
-       ret = tree_insert_offset(&cluster->root, entry);
+       ret = tree_insert_offset(ctl, cluster, entry);
        ASSERT(!ret); /* -EEXIST; Logic error */
 
        trace_btrfs_setup_cluster(block_group, cluster,
@@ -3477,7 +3490,7 @@ setup_cluster_no_bitmap(struct btrfs_block_group *block_group,
 
                rb_erase(&entry->offset_index, &ctl->free_space_offset);
                rb_erase_cached(&entry->bytes_index, &ctl->free_space_bytes);
-               ret = tree_insert_offset(&cluster->root, entry);
+               ret = tree_insert_offset(ctl, cluster, entry);
                total_size += entry->bytes;
                ASSERT(!ret); /* -EEXIST; Logic error */
        } while (node && entry != last);