btrfs: drop log root for dropped roots

If we fsync on a subvolume and create a log root for that volume, and
then later delete that subvolume we'll never clean up its log root.  Fix
this by making switch_commit_roots free the log for any dropped roots we
encounter.  The extra churn is because we need a btrfs_trans_handle, not
the btrfs_transaction.

CC: stable@vger.kernel.org # 5.4+
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c
index cfc08ef..55d8fd6 100644 (file)
--- a/fs/btrfs/transaction.c
+++ b/fs/btrfs/transaction.c
@@ -147,13 +147,14 @@ void btrfs_put_transaction(struct btrfs_transaction *transaction)
        }
 }
 
-static noinline void switch_commit_roots(struct btrfs_transaction *trans)
+static noinline void switch_commit_roots(struct btrfs_trans_handle *trans)
 {
+       struct btrfs_transaction *cur_trans = trans->transaction;
        struct btrfs_fs_info *fs_info = trans->fs_info;
        struct btrfs_root *root, *tmp;
 
        down_write(&fs_info->commit_root_sem);
-       list_for_each_entry_safe(root, tmp, &trans->switch_commits,
+       list_for_each_entry_safe(root, tmp, &cur_trans->switch_commits,
                                 dirty_list) {
                list_del_init(&root->dirty_list);
                free_extent_buffer(root->commit_root);
@@ -165,16 +166,17 @@ static noinline void switch_commit_roots(struct btrfs_transaction *trans)
        }
 
        /* We can free old roots now. */
-       spin_lock(&trans->dropped_roots_lock);
-       while (!list_empty(&trans->dropped_roots)) {
-               root = list_first_entry(&trans->dropped_roots,
+       spin_lock(&cur_trans->dropped_roots_lock);
+       while (!list_empty(&cur_trans->dropped_roots)) {
+               root = list_first_entry(&cur_trans->dropped_roots,
                                        struct btrfs_root, root_list);
                list_del_init(&root->root_list);
-               spin_unlock(&trans->dropped_roots_lock);
+               spin_unlock(&cur_trans->dropped_roots_lock);
+               btrfs_free_log(trans, root);
                btrfs_drop_and_free_fs_root(fs_info, root);
-               spin_lock(&trans->dropped_roots_lock);
+               spin_lock(&cur_trans->dropped_roots_lock);
        }
-       spin_unlock(&trans->dropped_roots_lock);
+       spin_unlock(&cur_trans->dropped_roots_lock);
        up_write(&fs_info->commit_root_sem);
 }
 
@@ -1421,7 +1423,7 @@ static int qgroup_account_snapshot(struct btrfs_trans_handle *trans,
        ret = commit_cowonly_roots(trans);
        if (ret)
                goto out;
-       switch_commit_roots(trans->transaction);
+       switch_commit_roots(trans);
        ret = btrfs_write_and_wait_transaction(trans);
        if (ret)
                btrfs_handle_fs_error(fs_info, ret,
@@ -2301,7 +2303,7 @@ int btrfs_commit_transaction(struct btrfs_trans_handle *trans)
        list_add_tail(&fs_info->chunk_root->dirty_list,
                      &cur_trans->switch_commits);
 
-       switch_commit_roots(cur_trans);
+       switch_commit_roots(trans);
 
        ASSERT(list_empty(&cur_trans->dirty_bgs));
        ASSERT(list_empty(&cur_trans->io_bgs));