[PATCH] f2fs: extract rb-tree operation infrastructure

From: Chao Yu
Date: Fri Apr 07 2017 - 06:30:25 EST

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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@xxxxxxxxxx>
---
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;
}
+
+ *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

Next message: Laxman Dewangan: "Re: [PATCH 1/1] gpio: core: Decouple open drain/source flag with active low/high"
Previous message: Joerg Roedel: "Re: AMD IOMMU causing filesystem corruption"
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