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Btrfs: introduce a head ref rbtree

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The way how we process delayed refs is
1) get a bunch of head refs,
2) pick up one head ref,
3) go one node back for any delayed ref updates.

The head ref is also linked in the same rbtree as the delayed ref is,
so in 1) stage, we have to walk one by one including not only head refs, but
delayed refs.

When we have a great number of delayed refs pending to process,
this'll cost time a lot.

Here we introduce a head ref specific rbtree, it only has head refs, so troubles
go away.

Signed-off-by: Liu Bo <bo.li.liu@oracle.com>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <clm@fb.com>
This commit is contained in:
Liu Bo
2013-10-14 12:59:45 +08:00
committed by Chris Mason
parent e20d6c5ba3
commit c46effa601
5 changed files with 98 additions and 59 deletions
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3
fs/btrfs/disk-io.c
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@@ -3842,6 +3842,9 @@ static int btrfs_destroy_delayed_refs(struct btrfs_transaction *trans,
ref->in_tree = 0;
rb_erase(&ref->rb_node, &delayed_refs->root);
if (head)
rb_erase(&head->href_node, &delayed_refs->href_root);
delayed_refs->num_entries--;
spin_unlock(&delayed_refs->lock);
if (head) {