Re: [PATCH] bcachefs: Re-add seemingly duplicate bch2_trans_begin()

Alan Huang
2025-06-08T10:05:27Z

On Jun 8, 2025, at 08:28, Kent Overstreet <kent.overstreet@linux.dev> wrote:
>
> Include a comment this time - we can't call iter_init() in a transaction
> restart, and write bufer flush doesn't guarantee that we aren't in a
> restart when it returns.

Why would it related to iter_init(), bch2_trans_begin(trans) is at the top of for_each_btree_key_max

>
> Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
> ---
> fs/bcachefs/movinggc.c | 6 ++++++
> 1 file changed, 6 insertions(+)
>
> diff --git a/fs/bcachefs/movinggc.c b/fs/bcachefs/movinggc.c
> index 6d7b1d5f7697..697d58b0bf91 100644
> --- a/fs/bcachefs/movinggc.c
> +++ b/fs/bcachefs/movinggc.c
> @@ -154,6 +154,12 @@ static int bch2_copygc_get_buckets(struct moving_context *ctxt,
> if (bch2_fs_fatal_err_on(ret, c, "%s: from bch2_btree_write_buffer_tryflush()", bch2_err_str(ret)))
> return ret;
>
> + /*
> + * we might be in a transaction restart from write buffer flush, start a
> + * new transaction before iter_init -> path_get
> + */
> + bch2_trans_begin(trans);
> +
> ret = for_each_btree_key_max(trans, iter, BTREE_ID_lru,
> lru_pos(BCH_LRU_BUCKET_FRAGMENTATION, 0, 0),
> lru_pos(BCH_LRU_BUCKET_FRAGMENTATION, U64_MAX, LRU_TIME_MAX),
> --
> 2.49.0
>