On 2020/3/14 上午5:09, Josef Bacik wrote:
> READA will generate a lot of extra reads for adjacent nodes, but when
> running delayed refs we have no idea if the next ref is going to be
> adjacent or not, so this potentially just generates a lot of extra IO.
> To make matters worse each ref is truly just looking for one item, it
> doesn't generally search forward, so we simply don't need it here.
>
> Signed-off-by: Josef Bacik <josef@xxxxxxxxxxxxxx>
Reviewed-by: Qu Wenruo <wqu@xxxxxxxx>
Thanks,
Qu
> ---
> fs/btrfs/extent-tree.c | 4 ----
> 1 file changed, 4 deletions(-)
>
> diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
> index a24ef1cef9fa..8e5b49baad98 100644
> --- a/fs/btrfs/extent-tree.c
> +++ b/fs/btrfs/extent-tree.c
> @@ -1469,7 +1469,6 @@ static int __btrfs_inc_extent_ref(struct btrfs_trans_handle *trans,
> if (!path)
> return -ENOMEM;
>
> - path->reada = READA_FORWARD;
> path->leave_spinning = 1;
> /* this will setup the path even if it fails to insert the back ref */
> ret = insert_inline_extent_backref(trans, path, bytenr, num_bytes,
> @@ -1494,7 +1493,6 @@ static int __btrfs_inc_extent_ref(struct btrfs_trans_handle *trans,
> btrfs_mark_buffer_dirty(leaf);
> btrfs_release_path(path);
>
> - path->reada = READA_FORWARD;
> path->leave_spinning = 1;
> /* now insert the actual backref */
> ret = insert_extent_backref(trans, path, bytenr, parent, root_objectid,
> @@ -1604,7 +1602,6 @@ static int run_delayed_extent_op(struct btrfs_trans_handle *trans,
> }
>
> again:
> - path->reada = READA_FORWARD;
> path->leave_spinning = 1;
> ret = btrfs_search_slot(trans, fs_info->extent_root, &key, path, 0, 1);
> if (ret < 0) {
> @@ -2999,7 +2996,6 @@ static int __btrfs_free_extent(struct btrfs_trans_handle *trans,
> if (!path)
> return -ENOMEM;
>
> - path->reada = READA_FORWARD;
> path->leave_spinning = 1;
>
> is_data = owner_objectid >= BTRFS_FIRST_FREE_OBJECTID;
>
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