From 07e1ce096db3605f3e0c98695df66a51e2be9f05 Mon Sep 17 00:00:00 2001 From: Liu Bo Date: Thu, 23 Aug 2018 03:51:52 +0800 Subject: [PATCH] Btrfs: extent_map: use rb_first_cached MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit rb_first_cached() trades an extra pointer "leftmost" for doing the same job as rb_first() but in O(1). As evict_inode_truncate_pages() removes all extent mapping by always looking for the first rb entry, it's helpful to use rb_first_cached instead. For more details about the optimization see patch "Btrfs: delayed-refs: use rb_first_cached for href_root". Tested-by: Holger Hoffstätte Signed-off-by: Liu Bo Reviewed-by: David Sterba Signed-off-by: David Sterba --- fs/btrfs/extent_map.c | 27 +++++++++++++++------------ fs/btrfs/extent_map.h | 2 +- fs/btrfs/inode.c | 4 ++-- fs/btrfs/tests/extent-map-tests.c | 4 ++-- fs/btrfs/volumes.c | 4 ++-- 5 files changed, 22 insertions(+), 19 deletions(-) diff --git a/fs/btrfs/extent_map.c b/fs/btrfs/extent_map.c index 2382b949cef8..7eea8b6e2cd3 100644 --- a/fs/btrfs/extent_map.c +++ b/fs/btrfs/extent_map.c @@ -34,7 +34,7 @@ void __cold extent_map_exit(void) */ void extent_map_tree_init(struct extent_map_tree *tree) { - tree->map = RB_ROOT; + tree->map = RB_ROOT_CACHED; INIT_LIST_HEAD(&tree->modified_extents); rwlock_init(&tree->lock); } @@ -90,24 +90,27 @@ static u64 range_end(u64 start, u64 len) return start + len; } -static int tree_insert(struct rb_root *root, struct extent_map *em) +static int tree_insert(struct rb_root_cached *root, struct extent_map *em) { - struct rb_node **p = &root->rb_node; + struct rb_node **p = &root->rb_root.rb_node; struct rb_node *parent = NULL; struct extent_map *entry = NULL; struct rb_node *orig_parent = NULL; u64 end = range_end(em->start, em->len); + bool leftmost = true; while (*p) { parent = *p; entry = rb_entry(parent, struct extent_map, rb_node); - if (em->start < entry->start) + if (em->start < entry->start) { p = &(*p)->rb_left; - else if (em->start >= extent_map_end(entry)) + } else if (em->start >= extent_map_end(entry)) { p = &(*p)->rb_right; - else + leftmost = false; + } else { return -EEXIST; + } } orig_parent = parent; @@ -130,7 +133,7 @@ static int tree_insert(struct rb_root *root, struct extent_map *em) return -EEXIST; rb_link_node(&em->rb_node, orig_parent, p); - rb_insert_color(&em->rb_node, root); + rb_insert_color_cached(&em->rb_node, root, leftmost); return 0; } @@ -242,7 +245,7 @@ static void try_merge_map(struct extent_map_tree *tree, struct extent_map *em) em->mod_start = merge->mod_start; em->generation = max(em->generation, merge->generation); - rb_erase(&merge->rb_node, &tree->map); + rb_erase_cached(&merge->rb_node, &tree->map); RB_CLEAR_NODE(&merge->rb_node); free_extent_map(merge); } @@ -254,7 +257,7 @@ static void try_merge_map(struct extent_map_tree *tree, struct extent_map *em) if (rb && mergable_maps(em, merge)) { em->len += merge->len; em->block_len += merge->block_len; - rb_erase(&merge->rb_node, &tree->map); + rb_erase_cached(&merge->rb_node, &tree->map); RB_CLEAR_NODE(&merge->rb_node); em->mod_len = (merge->mod_start + merge->mod_len) - em->mod_start; em->generation = max(em->generation, merge->generation); @@ -367,7 +370,7 @@ __lookup_extent_mapping(struct extent_map_tree *tree, struct rb_node *next = NULL; u64 end = range_end(start, len); - rb_node = __tree_search(&tree->map, start, &prev, &next); + rb_node = __tree_search(&tree->map.rb_root, start, &prev, &next); if (!rb_node) { if (prev) rb_node = prev; @@ -431,7 +434,7 @@ struct extent_map *search_extent_mapping(struct extent_map_tree *tree, void remove_extent_mapping(struct extent_map_tree *tree, struct extent_map *em) { WARN_ON(test_bit(EXTENT_FLAG_PINNED, &em->flags)); - rb_erase(&em->rb_node, &tree->map); + rb_erase_cached(&em->rb_node, &tree->map); if (!test_bit(EXTENT_FLAG_LOGGING, &em->flags)) list_del_init(&em->list); RB_CLEAR_NODE(&em->rb_node); @@ -446,7 +449,7 @@ void replace_extent_mapping(struct extent_map_tree *tree, ASSERT(extent_map_in_tree(cur)); if (!test_bit(EXTENT_FLAG_LOGGING, &cur->flags)) list_del_init(&cur->list); - rb_replace_node(&cur->rb_node, &new->rb_node, &tree->map); + rb_replace_node_cached(&cur->rb_node, &new->rb_node, &tree->map); RB_CLEAR_NODE(&cur->rb_node); setup_extent_mapping(tree, new, modified); diff --git a/fs/btrfs/extent_map.h b/fs/btrfs/extent_map.h index a7ceb30449fc..31977ffd6190 100644 --- a/fs/btrfs/extent_map.h +++ b/fs/btrfs/extent_map.h @@ -49,7 +49,7 @@ struct extent_map { }; struct extent_map_tree { - struct rb_root map; + struct rb_root_cached map; struct list_head modified_extents; rwlock_t lock; }; diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index 8ba7e5d5071e..dd2140d3e354 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -5222,10 +5222,10 @@ static void evict_inode_truncate_pages(struct inode *inode) truncate_inode_pages_final(&inode->i_data); write_lock(&map_tree->lock); - while (!RB_EMPTY_ROOT(&map_tree->map)) { + while (!RB_EMPTY_ROOT(&map_tree->map.rb_root)) { struct extent_map *em; - node = rb_first(&map_tree->map); + node = rb_first_cached(&map_tree->map); em = rb_entry(node, struct extent_map, rb_node); clear_bit(EXTENT_FLAG_PINNED, &em->flags); clear_bit(EXTENT_FLAG_LOGGING, &em->flags); diff --git a/fs/btrfs/tests/extent-map-tests.c b/fs/btrfs/tests/extent-map-tests.c index 385a5316e4bf..bf15d3a7f20e 100644 --- a/fs/btrfs/tests/extent-map-tests.c +++ b/fs/btrfs/tests/extent-map-tests.c @@ -12,8 +12,8 @@ static void free_extent_map_tree(struct extent_map_tree *em_tree) struct extent_map *em; struct rb_node *node; - while (!RB_EMPTY_ROOT(&em_tree->map)) { - node = rb_first(&em_tree->map); + while (!RB_EMPTY_ROOT(&em_tree->map.rb_root)) { + node = rb_first_cached(&em_tree->map); em = rb_entry(node, struct extent_map, rb_node); remove_extent_mapping(em_tree, em); diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c index 86c2330ac83f..909c578506ee 100644 --- a/fs/btrfs/volumes.c +++ b/fs/btrfs/volumes.c @@ -1613,7 +1613,7 @@ static u64 find_next_chunk(struct btrfs_fs_info *fs_info) em_tree = &fs_info->mapping_tree.map_tree; read_lock(&em_tree->lock); - n = rb_last(&em_tree->map); + n = rb_last(&em_tree->map.rb_root); if (n) { em = rb_entry(n, struct extent_map, rb_node); ret = em->start + em->len; @@ -7445,7 +7445,7 @@ static int verify_chunk_dev_extent_mapping(struct btrfs_fs_info *fs_info) int ret = 0; read_lock(&em_tree->lock); - for (node = rb_first(&em_tree->map); node; node = rb_next(node)) { + for (node = rb_first_cached(&em_tree->map); node; node = rb_next(node)) { em = rb_entry(node, struct extent_map, rb_node); if (em->map_lookup->num_stripes != em->map_lookup->verified_stripes) {