On Fri, Jan 17, 2020 at 2:14 PM Josef Bacik <josef@xxxxxxxxxxxxxx> 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. The extra churn is because we need a btrfs_trans_handle, not
> the btrfs_transaction.
>
> Signed-off-by: Josef Bacik <josef@xxxxxxxxxxxxxx>
Reviewed-by: Filipe Manana <fdmanana@xxxxxxxx>
Had already reviewed it last year, and still looks right to me.
Thanks.
> ---
> v1->v2:
> - Update commit message to indicate we need the trans_handle instead of the
> transaciton.
>
> 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));
> --
> 2.24.1
>
--
Filipe David Manana,
“Whether you think you can, or you think you can't — you're right.”
