On 15.10.2018 09:25, Lu Fengqi wrote:
> The find_ref_head shouldn't return the first entry even if no exact match
> is found. So move the hidden behavior to higher level.
>
> Besides, remove the useless local variables in the btrfs_select_ref_head.
>
> Signed-off-by: Lu Fengqi <lufq.f...@cn.fujitsu.com>
Reviewed-by: Nikolay Borisov <nbori...@suse.com>
> ---
> fs/btrfs/delayed-ref.c | 45 +++++++++++++++++++++++-------------------
> 1 file changed, 25 insertions(+), 20 deletions(-)
>
> diff --git a/fs/btrfs/delayed-ref.c b/fs/btrfs/delayed-ref.c
> index 6e8be384398e..a92f104cf06f 100644
> --- a/fs/btrfs/delayed-ref.c
> +++ b/fs/btrfs/delayed-ref.c
> @@ -164,14 +164,28 @@ static struct btrfs_delayed_ref_node*
> tree_insert(struct rb_root_cached *root,
> return NULL;
> }
>
> +static struct btrfs_delayed_ref_head *find_first_ref_head(
> + struct btrfs_delayed_ref_root *dr)
> +{
> + struct rb_node *n;
> + struct btrfs_delayed_ref_head *entry;
> +
> + n = rb_first_cached(&dr->href_root);
> + if (!n)
> + return NULL;
> +
> + entry = rb_entry(n, struct btrfs_delayed_ref_head, href_node);
> +
> + return entry;
> +}
> +
> /*
> * find an head entry based on bytenr. This returns the delayed ref
> * head if it was able to find one, or NULL if nothing was in that spot.
> * If return_bigger is given, the next bigger entry is returned if no exact
> - * match is found. But if no bigger one is found then the first node of the
> - * ref head tree will be returned.
> + * match is found.
> */
> -static struct btrfs_delayed_ref_head* find_ref_head(
> +static struct btrfs_delayed_ref_head *find_ref_head(
> struct btrfs_delayed_ref_root *dr, u64 bytenr,
> bool return_bigger)
> {
> @@ -195,10 +209,9 @@ static struct btrfs_delayed_ref_head* find_ref_head(
> if (bytenr > entry->bytenr) {
> n = rb_next(&entry->href_node);
> if (!n)
> - n = rb_first_cached(&dr->href_root);
> + return NULL;
> entry = rb_entry(n, struct btrfs_delayed_ref_head,
> href_node);
> - return entry;
> }
> return entry;
> }
> @@ -358,33 +371,25 @@ struct btrfs_delayed_ref_head *btrfs_select_ref_head(
> struct btrfs_delayed_ref_root *delayed_refs)
> {
> struct btrfs_delayed_ref_head *head;
> - u64 start;
> - bool loop = false;
>
> again:
> - start = delayed_refs->run_delayed_start;
> - head = find_ref_head(delayed_refs, start, true);
> - if (!head && !loop) {
> + head = find_ref_head(delayed_refs, delayed_refs->run_delayed_start,
> + true);
> + if (!head && delayed_refs->run_delayed_start != 0) {
> delayed_refs->run_delayed_start = 0;
> - start = 0;
> - loop = true;
> - head = find_ref_head(delayed_refs, start, true);
> - if (!head)
> - return NULL;
> - } else if (!head && loop) {
> - return NULL;
> + head = find_first_ref_head(delayed_refs);
> }
> + if (!head)
> + return NULL;
>
> while (head->processing) {
> struct rb_node *node;
>
> node = rb_next(&head->href_node);
> if (!node) {
> - if (loop)
> + if (delayed_refs->run_delayed_start == 0)
> return NULL;
> delayed_refs->run_delayed_start = 0;
> - start = 0;
> - loop = true;
> goto again;
> }
> head = rb_entry(node, struct btrfs_delayed_ref_head,
>
