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Date: Tue, 18 Jul 2017 18:46:01 -0700
From: Davidlohr Bueso <dave@...olabs.net>
To: akpm@...ux-foundation.org
Cc: mingo@...nel.org, peterz@...radead.org, jack@...e.cz,
torvalds@...ux-foundation.org, kirill.shutemov@...ux.intel.com,
hch@...radead.org, ldufour@...ux.vnet.ibm.com, mhocko@...e.com,
mgorman@...hsingularity.net, dave@...olabs.net,
linux-kernel@...r.kernel.org, tytso@....edu,
Davidlohr Bueso <dbueso@...e.de>
Subject: [PATCH 15/17] fs/ext4: use cached rbtrees
This patch replaces two uses of rbtrees to the cached version for
better rb_first() performance during:
* Tree traversals to mark blocks as used during ext4_mb_init_cache()
looping. (struct ext4_group_info)
* Storing ->curr_node for dx_readdir(). (struct dir_private_info)
Caching the leftmost node comes at negligible runtime cost, thus the
only downside is that the aforementioned structures are enlarged for
the extra pointer. No changes in semantics whatsoever.
Cc: tytso@....edu
Signed-off-by: Davidlohr Bueso <dbueso@...e.de>
---
This is part of the rbtree internal caching series:
https://lwn.net/Articles/726809/
fs/ext4/dir.c | 24 ++++++++++++++----------
fs/ext4/ext4.h | 4 ++--
fs/ext4/mballoc.c | 22 ++++++++++++----------
3 files changed, 28 insertions(+), 22 deletions(-)
diff --git a/fs/ext4/dir.c b/fs/ext4/dir.c
index e8b365000d73..011df6bba13c 100644
--- a/fs/ext4/dir.c
+++ b/fs/ext4/dir.c
@@ -391,18 +391,18 @@ struct fname {
* This functoin implements a non-recursive way of freeing all of the
* nodes in the red-black tree.
*/
-static void free_rb_tree_fname(struct rb_root *root)
+static void free_rb_tree_fname(struct rb_root_cached *root)
{
struct fname *fname, *next;
- rbtree_postorder_for_each_entry_safe(fname, next, root, rb_hash)
+ rbtree_postorder_for_each_entry_safe(fname, next, &root->rb_root, rb_hash)
while (fname) {
struct fname *old = fname;
fname = fname->next;
kfree(old);
}
- *root = RB_ROOT;
+ *root = RB_ROOT_CACHED;
}
@@ -441,9 +441,10 @@ int ext4_htree_store_dirent(struct file *dir_file, __u32 hash,
struct fname *fname, *new_fn;
struct dir_private_info *info;
int len;
+ bool leftmost = true;
info = dir_file->private_data;
- p = &info->root.rb_node;
+ p = &info->root.rb_root.rb_node;
/* Create and allocate the fname structure */
len = sizeof(struct fname) + ent_name->len + 1;
@@ -475,16 +476,19 @@ int ext4_htree_store_dirent(struct file *dir_file, __u32 hash,
if (new_fn->hash < fname->hash)
p = &(*p)->rb_left;
- else if (new_fn->hash > fname->hash)
+ else if (new_fn->hash > fname->hash) {
p = &(*p)->rb_right;
- else if (new_fn->minor_hash < fname->minor_hash)
+ leftmost = false;
+ } else if (new_fn->minor_hash < fname->minor_hash)
p = &(*p)->rb_left;
- else /* if (new_fn->minor_hash > fname->minor_hash) */
+ else { /* if (new_fn->minor_hash > fname->minor_hash) */
p = &(*p)->rb_right;
+ leftmost = false;
+ }
}
rb_link_node(&new_fn->rb_hash, parent, p);
- rb_insert_color(&new_fn->rb_hash, &info->root);
+ rb_insert_color_cached(&new_fn->rb_hash, &info->root, leftmost);
return 0;
}
@@ -558,7 +562,7 @@ static int ext4_dx_readdir(struct file *file, struct dir_context *ctx)
info->extra_fname = NULL;
goto next_node;
} else if (!info->curr_node)
- info->curr_node = rb_first(&info->root);
+ info->curr_node = rb_first_cached(&info->root);
while (1) {
/*
@@ -580,7 +584,7 @@ static int ext4_dx_readdir(struct file *file, struct dir_context *ctx)
ctx->pos = ext4_get_htree_eof(file);
break;
}
- info->curr_node = rb_first(&info->root);
+ info->curr_node = rb_first_cached(&info->root);
}
fname = rb_entry(info->curr_node, struct fname, rb_hash);
diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 9ebde0cd632e..0242c6801600 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -2116,7 +2116,7 @@ static inline bool ext4_is_quota_file(struct inode *inode)
* readdir operations in hash tree order.
*/
struct dir_private_info {
- struct rb_root root;
+ struct rb_root_cached root;
struct rb_node *curr_node;
struct fname *extra_fname;
loff_t last_pos;
@@ -2883,7 +2883,7 @@ int ext4_update_disksize_before_punch(struct inode *inode, loff_t offset,
struct ext4_group_info {
unsigned long bb_state;
- struct rb_root bb_free_root;
+ struct rb_root_cached bb_free_root;
ext4_grpblk_t bb_first_free; /* first free block */
ext4_grpblk_t bb_free; /* total free blocks */
ext4_grpblk_t bb_fragments; /* nr of freespace fragments */
diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index 581e357e8406..df36f9123a99 100644
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -2462,7 +2462,7 @@ int ext4_mb_add_groupinfo(struct super_block *sb, ext4_group_t group,
INIT_LIST_HEAD(&meta_group_info[i]->bb_prealloc_list);
init_rwsem(&meta_group_info[i]->alloc_sem);
- meta_group_info[i]->bb_free_root = RB_ROOT;
+ meta_group_info[i]->bb_free_root = RB_ROOT_CACHED;
meta_group_info[i]->bb_largest_free_order = -1; /* uninit */
#ifdef DOUBLE_CHECK
@@ -2824,7 +2824,7 @@ static void ext4_free_data_in_buddy(struct super_block *sb,
count2++;
ext4_lock_group(sb, entry->efd_group);
/* Take it out of per group rb tree */
- rb_erase(&entry->efd_node, &(db->bb_free_root));
+ rb_erase_cached(&entry->efd_node, &(db->bb_free_root));
mb_free_blocks(NULL, &e4b, entry->efd_start_cluster, entry->efd_count);
/*
@@ -2836,7 +2836,7 @@ static void ext4_free_data_in_buddy(struct super_block *sb,
if (!test_opt(sb, DISCARD))
EXT4_MB_GRP_CLEAR_TRIMMED(db);
- if (!db->bb_free_root.rb_node) {
+ if (!db->bb_free_root.rb_root.rb_node) {
/* No more items in the per group rb tree
* balance refcounts from ext4_mb_free_metadata()
*/
@@ -3519,7 +3519,7 @@ static void ext4_mb_generate_from_freelist(struct super_block *sb, void *bitmap,
struct ext4_free_data *entry;
grp = ext4_get_group_info(sb, group);
- n = rb_first(&(grp->bb_free_root));
+ n = rb_first_cached(&(grp->bb_free_root));
while (n) {
entry = rb_entry(n, struct ext4_free_data, efd_node);
@@ -4624,7 +4624,7 @@ ext4_fsblk_t ext4_mb_new_blocks(handle_t *handle,
static void ext4_try_merge_freed_extent(struct ext4_sb_info *sbi,
struct ext4_free_data *entry,
struct ext4_free_data *new_entry,
- struct rb_root *entry_rb_root)
+ struct rb_root_cached *entry_rb_root)
{
if ((entry->efd_tid != new_entry->efd_tid) ||
(entry->efd_group != new_entry->efd_group))
@@ -4641,7 +4641,7 @@ static void ext4_try_merge_freed_extent(struct ext4_sb_info *sbi,
spin_lock(&sbi->s_md_lock);
list_del(&entry->efd_list);
spin_unlock(&sbi->s_md_lock);
- rb_erase(&entry->efd_node, entry_rb_root);
+ rb_erase_cached(&entry->efd_node, entry_rb_root);
kmem_cache_free(ext4_free_data_cachep, entry);
}
@@ -4656,8 +4656,9 @@ ext4_mb_free_metadata(handle_t *handle, struct ext4_buddy *e4b,
struct ext4_group_info *db = e4b->bd_info;
struct super_block *sb = e4b->bd_sb;
struct ext4_sb_info *sbi = EXT4_SB(sb);
- struct rb_node **n = &db->bb_free_root.rb_node, *node;
+ struct rb_node **n = &db->bb_free_root.rb_root.rb_node, *node;
struct rb_node *parent = NULL, *new_node;
+ bool leftmost = true;
BUG_ON(!ext4_handle_valid(handle));
BUG_ON(e4b->bd_bitmap_page == NULL);
@@ -4680,9 +4681,10 @@ ext4_mb_free_metadata(handle_t *handle, struct ext4_buddy *e4b,
entry = rb_entry(parent, struct ext4_free_data, efd_node);
if (cluster < entry->efd_start_cluster)
n = &(*n)->rb_left;
- else if (cluster >= (entry->efd_start_cluster + entry->efd_count))
+ else if (cluster >= (entry->efd_start_cluster + entry->efd_count)) {
n = &(*n)->rb_right;
- else {
+ leftmost = false;
+ } else {
ext4_grp_locked_error(sb, group, 0,
ext4_group_first_block_no(sb, group) +
EXT4_C2B(sbi, cluster),
@@ -4692,7 +4694,7 @@ ext4_mb_free_metadata(handle_t *handle, struct ext4_buddy *e4b,
}
rb_link_node(new_node, parent, n);
- rb_insert_color(new_node, &db->bb_free_root);
+ rb_insert_color_cached(new_node, &db->bb_free_root, leftmost);
/* Now try to see the extent can be merged to left and right */
node = rb_prev(new_node);
--
2.12.0
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