From 1d16c2761bcc412ae4d9fb9fd9934cd426814191 Mon Sep 17 00:00:00 2001 From: Robbie Ko Date: Thu, 24 Oct 2024 10:31:42 +0800 Subject: [PATCH] btrfs: reduce extent tree lock contention when searching for inline backref When inserting extent backref, in order to check whether refs other than inline refs are used, we always use path keep locks for tree search, which will increase the lock contention of extent tree. We do not need the parent node every time to determine whether normal refs are used. It is only needed when the extent item is the last item in a leaf. Therefore, we change it to first use keep_locks=0 for search. If the extent item happens to be the last item in the leaf, we then change to keep_locks=1 for the second search to reduce lock contention. Reviewed-by: Filipe Manana Signed-off-by: Robbie Ko Signed-off-by: David Sterba --- fs/btrfs/extent-tree.c | 26 +++++++++++++++++++++++--- 1 file changed, 23 insertions(+), 3 deletions(-) diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c index e29024c66edbf..594d18ed908c4 100644 --- a/fs/btrfs/extent-tree.c +++ b/fs/btrfs/extent-tree.c @@ -795,7 +795,6 @@ int lookup_inline_extent_backref(struct btrfs_trans_handle *trans, if (insert) { extra_size = btrfs_extent_inline_ref_size(want); path->search_for_extension = 1; - path->keep_locks = 1; } else extra_size = -1; @@ -946,6 +945,25 @@ again: ret = -EAGAIN; goto out; } + + if (path->slots[0] + 1 < btrfs_header_nritems(path->nodes[0])) { + struct btrfs_key tmp_key; + + btrfs_item_key_to_cpu(path->nodes[0], &tmp_key, path->slots[0] + 1); + if (tmp_key.objectid == bytenr && + tmp_key.type < BTRFS_BLOCK_GROUP_ITEM_KEY) { + ret = -EAGAIN; + goto out; + } + goto out_no_entry; + } + + if (!path->keep_locks) { + btrfs_release_path(path); + path->keep_locks = 1; + goto again; + } + /* * To add new inline back ref, we have to make sure * there is no corresponding back ref item. @@ -959,13 +977,15 @@ again: goto out; } } +out_no_entry: *ref_ret = (struct btrfs_extent_inline_ref *)ptr; out: - if (insert) { + if (path->keep_locks) { path->keep_locks = 0; - path->search_for_extension = 0; btrfs_unlock_up_safe(path, 1); } + if (insert) + path->search_for_extension = 0; return ret; } -- 2.39.5