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Date: Mon, 10 Apr 2017 17:05:04 -0700
From: Jaegeuk Kim <jaegeuk@...nel.org>
To: Chao Yu <yuchao0@...wei.com>
Cc: linux-f2fs-devel@...ts.sourceforge.net,
linux-kernel@...r.kernel.org, chao@...nel.org
Subject: Re: [PATCH] f2fs: extract rb-tree operation infrastructure
Hi Chao,
On 04/07, Chao Yu wrote:
> rb-tree lookup/update functions are deeply coupled into extent cache
> codes, it's very hard to reuse these basic functions, this patch
> extracts common rb-tree operation infrastructure for latter reusing.
>
> Signed-off-by: Chao Yu <yuchao0@...wei.com>
> ---
> fs/f2fs/extent_cache.c | 293 ++++++++++++++++++++++++++++---------------------
> fs/f2fs/f2fs.h | 20 +++-
> 2 files changed, 182 insertions(+), 131 deletions(-)
>
> diff --git a/fs/f2fs/extent_cache.c b/fs/f2fs/extent_cache.c
> index c6934f014e0f..1a353f8c01d9 100644
> --- a/fs/f2fs/extent_cache.c
> +++ b/fs/f2fs/extent_cache.c
> @@ -18,6 +18,147 @@
> #include "node.h"
> #include <trace/events/f2fs.h>
>
> +static struct rb_entry *__lookup_rb_tree_fast(struct rb_entry *cached_re,
> + unsigned int ofs)
> +{
> + if (cached_re) {
> + if (cached_re->ofs <= ofs &&
> + cached_re->ofs + cached_re->len > ofs) {
> + return cached_re;
> + }
> + }
> +
> + return NULL;
> +}
> +
> +static struct rb_entry *__lookup_rb_tree_slow(struct rb_root *root,
> + unsigned int ofs)
> +{
> + struct rb_node *node = root->rb_node;
> + struct rb_entry *re;
> +
> + while (node) {
> + re = rb_entry(node, struct rb_entry, rb_node);
> +
> + if (ofs < re->ofs)
> + node = node->rb_left;
> + else if (ofs >= re->ofs + re->len)
> + node = node->rb_right;
> + else
> + return re;
> + }
> + return NULL;
> +}
> +
> +static struct rb_entry *__lookup_rb_tree(struct rb_root *root,
> + struct rb_entry *cached_re, unsigned int ofs)
> +{
> + struct rb_entry *re;
> +
> + re = __lookup_rb_tree_fast(cached_re, ofs);
> + if (!re)
> + return __lookup_rb_tree_slow(root, ofs);
> +
> + return re;
> +}
> +
> +static struct rb_node **__lookup_rb_tree_for_insert(struct f2fs_sb_info *sbi,
> + struct rb_root *root, struct rb_node **parent,
> + unsigned int ofs)
> +{
> + struct rb_node **p = &root->rb_node;
> + struct rb_entry *re;
> +
> + while (*p) {
> + *parent = *p;
> + re = rb_entry(*parent, struct rb_entry, rb_node);
> +
> + if (ofs < re->ofs)
> + p = &(*p)->rb_left;
> + else if (ofs >= re->ofs + re->len)
> + p = &(*p)->rb_right;
> + else
> + f2fs_bug_on(sbi, 1);
> + }
> +
> + return p;
> +}
> +
> +/*
> + * lookup rb entry in position of @ofs in rb-tree,
> + * if hit, return the entry, otherwise, return NULL
> + * @prev_ex: extent before ofs
> + * @next_ex: extent after ofs
> + * @insert_p: insert point for new extent at ofs
> + * in order to simpfy the insertion after.
> + * tree must stay unchanged between lookup and insertion.
> + */
> +static struct rb_entry *__lookup_rb_tree_ret(struct rb_root *root,
> + struct rb_entry *cached_re,
> + unsigned int ofs,
> + struct rb_entry **prev_entry,
> + struct rb_entry **next_entry,
> + struct rb_node ***insert_p,
> + struct rb_node **insert_parent)
> +{
> + struct rb_node **pnode = &root->rb_node;
> + struct rb_node *parent = NULL, *tmp_node;
> + struct rb_entry *re = cached_re;
> +
> + *insert_p = NULL;
> + *insert_parent = NULL;
> + *prev_entry = NULL;
> + *next_entry = NULL;
> +
> + if (RB_EMPTY_ROOT(root))
> + return NULL;
> +
> + if (re) {
> + if (re->ofs <= ofs && re->ofs + re->len > ofs)
> + goto lookup_neighbors;
> + }
> +
> + while (*pnode) {
> + parent = *pnode;
> + re = rb_entry(*pnode, struct rb_entry, rb_node);
> +
> + if (ofs < re->ofs)
> + pnode = &(*pnode)->rb_left;
> + else if (ofs >= re->ofs + re->len)
> + pnode = &(*pnode)->rb_right;
> + else
> + goto lookup_neighbors;
> + }
> +
> + *insert_p = pnode;
> + *insert_parent = parent;
> +
> + re = rb_entry(parent, struct rb_entry, rb_node);
> + tmp_node = parent;
> + if (parent && ofs > re->ofs)
> + tmp_node = rb_next(parent);
> + *next_entry = rb_entry_safe(tmp_node, struct rb_entry, rb_node);
> +
> + tmp_node = parent;
> + if (parent && ofs < re->ofs)
> + tmp_node = rb_prev(parent);
> + *prev_entry = rb_entry_safe(tmp_node, struct rb_entry, rb_node);
> + return NULL;
> +
> +lookup_neighbors:
> + if (ofs == re->ofs) {
> + /* lookup prev node for merging backward later */
> + tmp_node = rb_prev(&re->rb_node);
> + *prev_entry = rb_entry_safe(tmp_node, struct rb_entry, rb_node);
> + }
> + if (ofs == re->ofs + re->len - 1) {
> + /* lookup next node for merging frontward later */
> + tmp_node = rb_next(&re->rb_node);
> + *next_entry = rb_entry_safe(tmp_node, struct rb_entry, rb_node);
> + }
> + return re;
> +}
> +
> static struct kmem_cache *extent_tree_slab;
> static struct kmem_cache *extent_node_slab;
>
> @@ -102,36 +243,6 @@ static struct extent_tree *__grab_extent_tree(struct inode *inode)
> return et;
> }
>
> -static struct extent_node *__lookup_extent_tree(struct f2fs_sb_info *sbi,
> - struct extent_tree *et, unsigned int fofs)
> -{
> - struct rb_node *node = et->root.rb_node;
> - struct extent_node *en = et->cached_en;
> -
> - if (en) {
> - struct extent_info *cei = &en->ei;
> -
> - if (cei->fofs <= fofs && cei->fofs + cei->len > fofs) {
> - stat_inc_cached_node_hit(sbi);
> - return en;
> - }
> - }
> -
> - while (node) {
> - en = rb_entry(node, struct extent_node, rb_node);
> -
> - if (fofs < en->ei.fofs) {
> - node = node->rb_left;
> - } else if (fofs >= en->ei.fofs + en->ei.len) {
> - node = node->rb_right;
> - } else {
> - stat_inc_rbtree_node_hit(sbi);
> - return en;
> - }
> - }
> - return NULL;
> -}
> -
> static struct extent_node *__init_extent_tree(struct f2fs_sb_info *sbi,
> struct extent_tree *et, struct extent_info *ei)
> {
> @@ -237,17 +348,27 @@ static bool f2fs_lookup_extent_tree(struct inode *inode, pgoff_t pgofs,
> goto out;
> }
>
> - en = __lookup_extent_tree(sbi, et, pgofs);
> + en = (struct extent_node *)__lookup_rb_tree_fast(
> + (struct rb_entry *)et->cached_en, pgofs);
> if (en) {
> - *ei = en->ei;
> - spin_lock(&sbi->extent_lock);
> - if (!list_empty(&en->list)) {
> - list_move_tail(&en->list, &sbi->extent_list);
> - et->cached_en = en;
> - }
> - spin_unlock(&sbi->extent_lock);
> - ret = true;
> + stat_inc_cached_node_hit(sbi);
> + } else {
> + en = (struct extent_node *)__lookup_rb_tree_slow(&et->root,
> + pgofs);
> + if (en)
> + stat_inc_rbtree_node_hit(sbi);
> + else
> + goto out;
> }
We can use __lookup_rb_tree() like this?
---
fs/f2fs/extent_cache.c | 18 +++++++-----------
1 file changed, 7 insertions(+), 11 deletions(-)
diff --git a/fs/f2fs/extent_cache.c b/fs/f2fs/extent_cache.c
index 1a353f8c01d9..9b86d549a829 100644
--- a/fs/f2fs/extent_cache.c
+++ b/fs/f2fs/extent_cache.c
@@ -27,7 +27,6 @@ static struct rb_entry *__lookup_rb_tree_fast(struct rb_entry *cached_re,
return cached_re;
}
}
-
return NULL;
}
@@ -348,18 +347,15 @@ static bool f2fs_lookup_extent_tree(struct inode *inode, pgoff_t pgofs,
goto out;
}
- en = (struct extent_node *)__lookup_rb_tree_fast(
+ en = (struct extent_node *)__lookup_rb_tree(&et->root,
(struct rb_entry *)et->cached_en, pgofs);
- if (en) {
+ if (!en)
+ goto out;
+
+ if (en == et->cached_en)
stat_inc_cached_node_hit(sbi);
- } else {
- en = (struct extent_node *)__lookup_rb_tree_slow(&et->root,
- pgofs);
- if (en)
- stat_inc_rbtree_node_hit(sbi);
- else
- goto out;
- }
+ else
+ stat_inc_rbtree_node_hit(sbi);
*ei = en->ei;
spin_lock(&sbi->extent_lock);
--
2.11.0
> +
> + *ei = en->ei;
> + spin_lock(&sbi->extent_lock);
> + if (!list_empty(&en->list)) {
> + list_move_tail(&en->list, &sbi->extent_list);
> + et->cached_en = en;
> + }
> + spin_unlock(&sbi->extent_lock);
> + ret = true;
> out:
> stat_inc_total_hit(sbi);
> read_unlock(&et->lock);
> @@ -256,83 +377,6 @@ static bool f2fs_lookup_extent_tree(struct inode *inode, pgoff_t pgofs,
> return ret;
> }
>
> -
> -/*
> - * lookup extent at @fofs, if hit, return the extent
> - * if not, return NULL and
> - * @prev_ex: extent before fofs
> - * @next_ex: extent after fofs
> - * @insert_p: insert point for new extent at fofs
> - * in order to simpfy the insertion after.
> - * tree must stay unchanged between lookup and insertion.
> - */
> -static struct extent_node *__lookup_extent_tree_ret(struct extent_tree *et,
> - unsigned int fofs,
> - struct extent_node **prev_ex,
> - struct extent_node **next_ex,
> - struct rb_node ***insert_p,
> - struct rb_node **insert_parent)
> -{
> - struct rb_node **pnode = &et->root.rb_node;
> - struct rb_node *parent = NULL, *tmp_node;
> - struct extent_node *en = et->cached_en;
> -
> - *insert_p = NULL;
> - *insert_parent = NULL;
> - *prev_ex = NULL;
> - *next_ex = NULL;
> -
> - if (RB_EMPTY_ROOT(&et->root))
> - return NULL;
> -
> - if (en) {
> - struct extent_info *cei = &en->ei;
> -
> - if (cei->fofs <= fofs && cei->fofs + cei->len > fofs)
> - goto lookup_neighbors;
> - }
> -
> - while (*pnode) {
> - parent = *pnode;
> - en = rb_entry(*pnode, struct extent_node, rb_node);
> -
> - if (fofs < en->ei.fofs)
> - pnode = &(*pnode)->rb_left;
> - else if (fofs >= en->ei.fofs + en->ei.len)
> - pnode = &(*pnode)->rb_right;
> - else
> - goto lookup_neighbors;
> - }
> -
> - *insert_p = pnode;
> - *insert_parent = parent;
> -
> - en = rb_entry(parent, struct extent_node, rb_node);
> - tmp_node = parent;
> - if (parent && fofs > en->ei.fofs)
> - tmp_node = rb_next(parent);
> - *next_ex = rb_entry_safe(tmp_node, struct extent_node, rb_node);
> -
> - tmp_node = parent;
> - if (parent && fofs < en->ei.fofs)
> - tmp_node = rb_prev(parent);
> - *prev_ex = rb_entry_safe(tmp_node, struct extent_node, rb_node);
> - return NULL;
> -
> -lookup_neighbors:
> - if (fofs == en->ei.fofs) {
> - /* lookup prev node for merging backward later */
> - tmp_node = rb_prev(&en->rb_node);
> - *prev_ex = rb_entry_safe(tmp_node, struct extent_node, rb_node);
> - }
> - if (fofs == en->ei.fofs + en->ei.len - 1) {
> - /* lookup next node for merging frontward later */
> - tmp_node = rb_next(&en->rb_node);
> - *next_ex = rb_entry_safe(tmp_node, struct extent_node, rb_node);
> - }
> - return en;
> -}
> -
> static struct extent_node *__try_merge_extent_node(struct inode *inode,
> struct extent_tree *et, struct extent_info *ei,
> struct extent_node *prev_ex,
> @@ -387,17 +431,7 @@ static struct extent_node *__insert_extent_tree(struct inode *inode,
> goto do_insert;
> }
>
> - while (*p) {
> - parent = *p;
> - en = rb_entry(parent, struct extent_node, rb_node);
> -
> - if (ei->fofs < en->ei.fofs)
> - p = &(*p)->rb_left;
> - else if (ei->fofs >= en->ei.fofs + en->ei.len)
> - p = &(*p)->rb_right;
> - else
> - f2fs_bug_on(sbi, 1);
> - }
> + p = __lookup_rb_tree_for_insert(sbi, &et->root, &parent, ei->fofs);
> do_insert:
> en = __attach_extent_node(sbi, et, ei, parent, p);
> if (!en)
> @@ -447,7 +481,10 @@ static void f2fs_update_extent_tree_range(struct inode *inode,
> __drop_largest_extent(inode, fofs, len);
>
> /* 1. lookup first extent node in range [fofs, fofs + len - 1] */
> - en = __lookup_extent_tree_ret(et, fofs, &prev_en, &next_en,
> + en = (struct extent_node *)__lookup_rb_tree_ret(&et->root,
> + (struct rb_entry *)et->cached_en, fofs,
> + (struct rb_entry **)&prev_en,
> + (struct rb_entry **)&next_en,
> &insert_p, &insert_parent);
> if (!en)
> en = next_en;
> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> index 5a2b8cd13c92..407a21a09fb7 100644
> --- a/fs/f2fs/f2fs.h
> +++ b/fs/f2fs/f2fs.h
> @@ -380,16 +380,30 @@ enum {
> /* number of extent info in extent cache we try to shrink */
> #define EXTENT_CACHE_SHRINK_NUMBER 128
>
> +struct rb_entry {
> + struct rb_node rb_node; /* rb node located in rb-tree */
> + unsigned int ofs; /* start offset of the entry */
> + unsigned int len; /* length of the entry */
> +};
> +
> struct extent_info {
> unsigned int fofs; /* start offset in a file */
> - u32 blk; /* start block address of the extent */
> unsigned int len; /* length of the extent */
> + u32 blk; /* start block address of the extent */
> };
>
> struct extent_node {
> - struct rb_node rb_node; /* rb node located in rb-tree */
> + struct rb_node rb_node;
> + union {
> + struct {
> + unsigned int fofs;
> + unsigned int len;
> + u32 blk;
> + };
> + struct extent_info ei; /* extent info */
> +
> + };
> struct list_head list; /* node in global extent list of sbi */
> - struct extent_info ei; /* extent info */
> struct extent_tree *et; /* extent tree pointer */
> };
>
> --
> 2.12.2.510.ge1104a5ee539
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