Re: [PATCH 1/5] btrfs: drop log root for dropped roots

[Filipe Manana <fdmanana@gmail.com>]

On Fri, Dec 6, 2019 at 2:38 PM Josef Bacik <josef@toxicpanda.com> wrote:
>
> 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.
>
> Signed-off-by: Josef Bacik <josef@toxicpanda.com>

Reviewed-by: Filipe Manana <fdmanana@suse.com>

Looks good, thanks.

> ---
>  fs/btrfs/transaction.c | 22 ++++++++++++----------
>  1 file changed, 12 insertions(+), 10 deletions(-)
>
> diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c
> index cfc08ef9b876..55d8fd68775a 100644
> --- 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));
> --
> 2.23.0
>


-- 
Filipe David Manana,

“Whether you think you can, or you think you can't — you're right.”