From c6fc24549960f26910cd0c6e4b5f48f2f306b11d Mon Sep 17 00:00:00 2001 From: Qu Wenruo Date: Mon, 30 Mar 2015 17:03:00 +0800 Subject: btrfs: delayed-ref: Use list to replace the ref_root in ref_head. This patch replace the rbtree used in ref_head to list. This has the following advantage: 1) Easier merge logic. With the new list implement, we only need to care merging the tail ref_node with the new ref_node. And this can be done quite easy at insert time, no need to do a indicated merge at run_delayed_refs(). Signed-off-by: Qu Wenruo Signed-off-by: Chris Mason --- fs/btrfs/delayed-ref.h | 18 +++++++++++++++++- 1 file changed, 17 insertions(+), 1 deletion(-) (limited to 'fs/btrfs/delayed-ref.h') diff --git a/fs/btrfs/delayed-ref.h b/fs/btrfs/delayed-ref.h index 5eb0892396d0..362ca57cfeb7 100644 --- a/fs/btrfs/delayed-ref.h +++ b/fs/btrfs/delayed-ref.h @@ -24,9 +24,25 @@ #define BTRFS_ADD_DELAYED_EXTENT 3 /* record a full extent allocation */ #define BTRFS_UPDATE_DELAYED_HEAD 4 /* not changing ref count on head ref */ +/* + * XXX: Qu: I really hate the design that ref_head and tree/data ref shares the + * same ref_node structure. + * Ref_head is in a higher logic level than tree/data ref, and duplicated + * bytenr/num_bytes in ref_node is really a waste or memory, they should be + * referred from ref_head. + * This gets more disgusting after we use list to store tree/data ref in + * ref_head. Must clean this mess up later. + */ struct btrfs_delayed_ref_node { + /* + * ref_head use rb tree, stored in ref_root->href. + * indexed by bytenr + */ struct rb_node rb_node; + /*data/tree ref use list, stored in ref_head->ref_list. */ + struct list_head list; + /* the starting bytenr of the extent */ u64 bytenr; @@ -83,7 +99,7 @@ struct btrfs_delayed_ref_head { struct mutex mutex; spinlock_t lock; - struct rb_root ref_root; + struct list_head ref_list; struct rb_node href_node; -- cgit v1.2.3