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Btrfs: extent_map: use rb_first_cached 

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 <holger@applied-asynchrony.com>
Signed-off-by: Liu Bo <bo.liu@linux.alibaba.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
Liu Bo 2018-08-23 03:51:52 +08:00 committed by David Sterba
parent 03a1d4c891
commit 07e1ce096d
5 changed files with 22 additions and 19 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

27
fs/btrfs/extent_map.c
View File

@ -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);

2
fs/btrfs/extent_map.h
View File

@ -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;
};

4
fs/btrfs/inode.c
View File

@ -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);

4
fs/btrfs/tests/extent-map-tests.c
View File

@ -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);

4
fs/btrfs/volumes.c
View File

@ -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) {