Re: [PATCH 04/35] btrfs: only track ref_heads in delayed_ref_updates

Nikolay Borisov
2018-08-31T11:59:08Z

On 30.08.2018 20:41, Josef Bacik wrote:
> From: Josef Bacik <jbacik@fb.com>
>
> We use this number to figure out how many delayed refs to run, but
> __btrfs_run_delayed_refs really only checks every time we need a new
> delayed ref head, so we always run at least one ref head completely no
> matter what the number of items on it. So instead track only the ref
> heads added by this trans handle and adjust the counting appropriately
> in __btrfs_run_delayed_refs.
>
> Signed-off-by: Josef Bacik <jbacik@fb.com>
> ---
> fs/btrfs/delayed-ref.c | 3 ---
> fs/btrfs/extent-tree.c | 5 +----
> 2 files changed, 1 insertion(+), 7 deletions(-)
>
> diff --git a/fs/btrfs/delayed-ref.c b/fs/btrfs/delayed-ref.c
> index 3a9e4ac21794..27f7dd4e3d52 100644
> --- a/fs/btrfs/delayed-ref.c
> +++ b/fs/btrfs/delayed-ref.c
> @@ -234,8 +234,6 @@ static inline void drop_delayed_ref(struct btrfs_trans_handle *trans,
> ref->in_tree = 0;
> btrfs_put_delayed_ref(ref);
> atomic_dec(&delayed_refs->num_entries);
> - if (trans->delayed_ref_updates)
> - trans->delayed_ref_updates--;

There was feedback on this particular hunk and you've completely ignored
it, that's not nice:

https://www.spinics.net/lists/linux-btrfs/msg80514.html

> }
>
> static bool merge_ref(struct btrfs_trans_handle *trans,
> @@ -460,7 +458,6 @@ static int insert_delayed_ref(struct btrfs_trans_handle *trans,
> if (ref->action == BTRFS_ADD_DELAYED_REF)
> list_add_tail(&ref->add_list, &href->ref_add_list);
> atomic_inc(&root->num_entries);
> - trans->delayed_ref_updates++;
> spin_unlock(&href->lock);
> return ret;
> }
> diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
> index 87c42a2c45b1..20531389a20a 100644
> --- a/fs/btrfs/extent-tree.c
> +++ b/fs/btrfs/extent-tree.c
> @@ -2583,6 +2583,7 @@ static noinline int __btrfs_run_delayed_refs(struct btrfs_trans_handle *trans,
> spin_unlock(&delayed_refs->lock);
> break;
> }
> + count++;
>
> /* grab the lock that says we are going to process
> * all the refs for this head */
> @@ -2596,7 +2597,6 @@ static noinline int __btrfs_run_delayed_refs(struct btrfs_trans_handle *trans,
> */
> if (ret == -EAGAIN) {
> locked_ref = NULL;
> - count++;
> continue;
> }
> }
> @@ -2624,7 +2624,6 @@ static noinline int __btrfs_run_delayed_refs(struct btrfs_trans_handle *trans,
> unselect_delayed_ref_head(delayed_refs, locked_ref);
> locked_ref = NULL;
> cond_resched();
> - count++;
> continue;
> }
>
> @@ -2642,7 +2641,6 @@ static noinline int __btrfs_run_delayed_refs(struct btrfs_trans_handle *trans,
> return ret;
> }
> locked_ref = NULL;
> - count++;
> continue;
> }
>
> @@ -2693,7 +2691,6 @@ static noinline int __btrfs_run_delayed_refs(struct btrfs_trans_handle *trans,
> }
>
> btrfs_put_delayed_ref(ref);
> - count++;
> cond_resched();
> }
>
>