[PATCH v3 06/10] f2fs: add core functions for rb-tree extent cache
From: Chao Yu
Date: Thu Feb 05 2015 - 04:55:33 EST
This patch adds core functions including slab cache init function and
init/lookup/update/shrink/destroy function for rb-tree based extent cache.
Thank Jaegeuk Kim and Changman Lee as they gave much suggestion about detail
design and implementation of extent cache.
Todo:
* register rb-based extent cache shrink with mm shrink interface.
v2:
o move set_extent_info and __is_{extent,back,front}_mergeable into f2fs.h.
o introduce __{attach,detach}_extent_node for code readability.
o add cond_resched() when fail to invoke kmem_cache_alloc/radix_tree_insert.
o fix some coding style and typo issues.
v3:
o fix oops due to using an unassigned pointer.
o use list_del to remove extent node in shrink list.
Signed-off-by: Chao Yu <chao2.yu@xxxxxxxxxxx>
Signed-off-by: Jaegeuk Kim <jaegeuk@xxxxxxxxxx>
Signed-off-by: Changman Lee <cm224.lee@xxxxxxxxxxx>
---
fs/f2fs/data.c | 411 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
fs/f2fs/f2fs.h | 27 ++++
fs/f2fs/node.c | 9 +-
3 files changed, 446 insertions(+), 1 deletion(-)
diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
index c805d2a..4b240fb 100644
--- a/fs/f2fs/data.c
+++ b/fs/f2fs/data.c
@@ -25,6 +25,9 @@
#include "trace.h"
#include <trace/events/f2fs.h>
+struct kmem_cache *extent_tree_slab;
+struct kmem_cache *extent_node_slab;
+
static void f2fs_read_end_io(struct bio *bio, int err)
{
struct bio_vec *bvec;
@@ -366,6 +369,383 @@ end_update:
return need_update;
}
+struct extent_node *__attach_extent_node(struct f2fs_sb_info *sbi,
+ struct extent_tree *et, struct extent_info *ei,
+ struct rb_node *parent, struct rb_node **p)
+{
+ struct extent_node *en;
+
+ en = kmem_cache_alloc(extent_node_slab, GFP_ATOMIC);
+ if (!en)
+ return NULL;
+
+ en->ei = *ei;
+ INIT_LIST_HEAD(&en->list);
+
+ rb_link_node(&en->rb_node, parent, p);
+ rb_insert_color(&en->rb_node, &et->root);
+ et->count++;
+ atomic_inc(&sbi->total_ext_node);
+ return en;
+}
+
+static void __detach_extent_node(struct f2fs_sb_info *sbi,
+ struct extent_tree *et, struct extent_node *en)
+{
+ rb_erase(&en->rb_node, &et->root);
+ et->count--;
+ atomic_dec(&sbi->total_ext_node);
+}
+
+static struct extent_node *__lookup_extent_tree(struct extent_tree *et,
+ unsigned int fofs)
+{
+ struct rb_node *node = et->root.rb_node;
+ struct extent_node *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
+ return en;
+ }
+ return NULL;
+}
+
+static struct extent_node *__try_back_merge(struct f2fs_sb_info *sbi,
+ struct extent_tree *et, struct extent_node *en)
+{
+ struct extent_node *prev;
+ struct rb_node *node;
+
+ node = rb_prev(&en->rb_node);
+ if (!node)
+ return NULL;
+
+ prev = rb_entry(node, struct extent_node, rb_node);
+ if (__is_back_mergeable(&en->ei, &prev->ei)) {
+ en->ei.fofs = prev->ei.fofs;
+ en->ei.blk = prev->ei.blk;
+ en->ei.len += prev->ei.len;
+ __detach_extent_node(sbi, et, prev);
+ return prev;
+ }
+ return NULL;
+}
+
+static struct extent_node *__try_front_merge(struct f2fs_sb_info *sbi,
+ struct extent_tree *et, struct extent_node *en)
+{
+ struct extent_node *next;
+ struct rb_node *node;
+
+ node = rb_next(&en->rb_node);
+ if (!node)
+ return NULL;
+
+ next = rb_entry(node, struct extent_node, rb_node);
+ if (__is_front_mergeable(&en->ei, &next->ei)) {
+ en->ei.len += next->ei.len;
+ __detach_extent_node(sbi, et, next);
+ return next;
+ }
+ return NULL;
+}
+
+static struct extent_node *__insert_extent_tree(struct f2fs_sb_info *sbi,
+ struct extent_tree *et, struct extent_info *ei,
+ struct extent_node **den)
+{
+ struct rb_node **p = &et->root.rb_node;
+ struct rb_node *parent = NULL;
+ struct extent_node *en;
+
+ while (*p) {
+ parent = *p;
+ en = rb_entry(parent, struct extent_node, rb_node);
+
+ if (ei->fofs < en->ei.fofs) {
+ if (__is_front_mergeable(ei, &en->ei)) {
+ f2fs_bug_on(sbi, !den);
+ en->ei.fofs = ei->fofs;
+ en->ei.blk = ei->blk;
+ en->ei.len += ei->len;
+ *den = __try_back_merge(sbi, et, en);
+ return en;
+ }
+ p = &(*p)->rb_left;
+ } else if (ei->fofs >= en->ei.fofs + en->ei.len) {
+ if (__is_back_mergeable(ei, &en->ei)) {
+ f2fs_bug_on(sbi, !den);
+ en->ei.len += ei->len;
+ *den = __try_front_merge(sbi, et, en);
+ return en;
+ }
+ p = &(*p)->rb_right;
+ } else {
+ f2fs_bug_on(sbi, 1);
+ }
+ }
+
+ return __attach_extent_node(sbi, et, ei, parent, p);
+}
+
+static unsigned int __free_extent_tree(struct f2fs_sb_info *sbi,
+ struct extent_tree *et, bool free_all)
+{
+ struct rb_node *node, *next;
+ struct extent_node *en;
+ unsigned int count = et->count;
+
+ node = rb_first(&et->root);
+ while (node) {
+ next = rb_next(node);
+ en = rb_entry(node, struct extent_node, rb_node);
+
+ if (free_all) {
+ spin_lock(&sbi->extent_lock);
+ if (!list_empty(&en->list))
+ list_del_init(&en->list);
+ spin_unlock(&sbi->extent_lock);
+ }
+
+ if (free_all || list_empty(&en->list)) {
+ __detach_extent_node(sbi, et, en);
+ kmem_cache_free(extent_node_slab, en);
+ }
+ node = next;
+ }
+
+ return count - et->count;
+}
+
+static bool f2fs_lookup_extent_tree(struct inode *inode, pgoff_t pgofs,
+ struct extent_info *ei)
+{
+ struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
+ struct extent_tree *et;
+ struct extent_node *en;
+
+ if (is_inode_flag_set(F2FS_I(inode), FI_NO_EXTENT))
+ return false;
+
+ down_read(&sbi->extent_tree_lock);
+ et = radix_tree_lookup(&sbi->extent_tree_root, inode->i_ino);
+ if (!et) {
+ up_read(&sbi->extent_tree_lock);
+ return false;
+ }
+ atomic_inc(&et->refcount);
+ up_read(&sbi->extent_tree_lock);
+
+ read_lock(&et->lock);
+ en = __lookup_extent_tree(et, pgofs);
+ if (en) {
+ *ei = en->ei;
+ spin_lock(&sbi->extent_lock);
+ if (!list_empty(&en->list))
+ list_move_tail(&en->list, &sbi->extent_list);
+ spin_unlock(&sbi->extent_lock);
+ stat_inc_read_hit(sbi->sb);
+ }
+ stat_inc_total_hit(sbi->sb);
+ read_unlock(&et->lock);
+
+ atomic_dec(&et->refcount);
+ return en ? true : false;
+}
+
+static void f2fs_update_extent_tree(struct inode *inode, pgoff_t fofs,
+ block_t blkaddr)
+{
+ struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
+ nid_t ino = inode->i_ino;
+ struct extent_tree *et;
+ struct extent_node *en = NULL, *en1 = NULL, *en2 = NULL, *en3 = NULL;
+ struct extent_node *den = NULL;
+ struct extent_info ei, dei;
+ unsigned int endofs;
+
+ if (is_inode_flag_set(F2FS_I(inode), FI_NO_EXTENT))
+ return;
+
+ down_write(&sbi->extent_tree_lock);
+ et = radix_tree_lookup(&sbi->extent_tree_root, ino);
+ if (!et) {
+ et = f2fs_kmem_cache_alloc(extent_tree_slab, GFP_NOFS);
+ f2fs_radix_tree_insert(&sbi->extent_tree_root, ino, et);
+ memset(et, 0, sizeof(struct extent_tree));
+ et->ino = ino;
+ et->root = RB_ROOT;
+ rwlock_init(&et->lock);
+ atomic_set(&et->refcount, 0);
+ et->count = 0;
+ sbi->total_ext_tree++;
+ }
+ atomic_inc(&et->refcount);
+ up_write(&sbi->extent_tree_lock);
+
+ write_lock(&et->lock);
+
+ /* 1. lookup and remove existing extent info in cache */
+ en = __lookup_extent_tree(et, fofs);
+ if (!en)
+ goto update_extent;
+
+ dei = en->ei;
+ __detach_extent_node(sbi, et, en);
+
+ /* 2. if extent can be split more, split and insert the left part */
+ if (dei.len > 1) {
+ /* insert left part of split extent into cache */
+ if (fofs - dei.fofs >= F2FS_MIN_EXTENT_LEN) {
+ set_extent_info(&ei, dei.fofs, dei.blk,
+ fofs - dei.fofs);
+ en1 = __insert_extent_tree(sbi, et, &ei, NULL);
+ }
+
+ /* insert right part of split extent into cache */
+ endofs = dei.fofs + dei.len - 1;
+ if (endofs - fofs >= F2FS_MIN_EXTENT_LEN) {
+ set_extent_info(&ei, fofs + 1,
+ fofs - dei.fofs + dei.blk, endofs - fofs);
+ en2 = __insert_extent_tree(sbi, et, &ei, NULL);
+ }
+ }
+
+update_extent:
+ /* 3. update extent in extent cache */
+ if (blkaddr) {
+ set_extent_info(&ei, fofs, blkaddr, 1);
+ en3 = __insert_extent_tree(sbi, et, &ei, &den);
+ }
+
+ /* 4. update in global extent list */
+ spin_lock(&sbi->extent_lock);
+ if (en && !list_empty(&en->list))
+ list_del(&en->list);
+ /*
+ * en1 and en2 split from en, they will become more and more smaller
+ * fragments after splitting several times. So if the length is smaller
+ * than F2FS_MIN_EXTENT_LEN, we will not add them into extent tree.
+ */
+ if (en1)
+ list_add_tail(&en1->list, &sbi->extent_list);
+ if (en2)
+ list_add_tail(&en2->list, &sbi->extent_list);
+ if (en3) {
+ if (list_empty(&en3->list))
+ list_add_tail(&en3->list, &sbi->extent_list);
+ else
+ list_move_tail(&en3->list, &sbi->extent_list);
+ }
+ if (den && !list_empty(&den->list))
+ list_del(&den->list);
+ spin_unlock(&sbi->extent_lock);
+
+ /* 5. release extent node */
+ if (en)
+ kmem_cache_free(extent_node_slab, en);
+ if (den)
+ kmem_cache_free(extent_node_slab, den);
+
+ write_unlock(&et->lock);
+ atomic_dec(&et->refcount);
+}
+
+void f2fs_shrink_extent_tree(struct f2fs_sb_info *sbi, int nr_shrink)
+{
+ struct extent_tree *treevec[EXT_TREE_VEC_SIZE];
+ struct extent_node *en, *tmp;
+ unsigned long ino = F2FS_ROOT_INO(sbi);
+ struct radix_tree_iter iter;
+ void **slot;
+ unsigned int found;
+
+ if (available_free_memory(sbi, EXTENT_CACHE))
+ return;
+
+ spin_lock(&sbi->extent_lock);
+ list_for_each_entry_safe(en, tmp, &sbi->extent_list, list) {
+ if (!nr_shrink--)
+ break;
+ list_del_init(&en->list);
+ }
+ spin_unlock(&sbi->extent_lock);
+
+ down_read(&sbi->extent_tree_lock);
+ while ((found = radix_tree_gang_lookup(&sbi->extent_tree_root,
+ (void **)treevec, ino, EXT_TREE_VEC_SIZE))) {
+ unsigned i;
+
+ ino = treevec[found - 1]->ino + 1;
+ for (i = 0; i < found; i++) {
+ struct extent_tree *et = treevec[i];
+
+ atomic_inc(&et->refcount);
+ write_lock(&et->lock);
+ __free_extent_tree(sbi, et, false);
+ write_unlock(&et->lock);
+ atomic_dec(&et->refcount);
+ }
+ }
+ up_read(&sbi->extent_tree_lock);
+
+ down_write(&sbi->extent_tree_lock);
+ radix_tree_for_each_slot(slot, &sbi->extent_tree_root, &iter,
+ F2FS_ROOT_INO(sbi)) {
+ struct extent_tree *et = (struct extent_tree *)*slot;
+
+ if (!atomic_read(&et->refcount) && !et->count) {
+ radix_tree_delete(&sbi->extent_tree_root, et->ino);
+ kmem_cache_free(extent_tree_slab, et);
+ sbi->total_ext_tree--;
+ }
+ }
+ up_write(&sbi->extent_tree_lock);
+}
+
+void f2fs_destroy_extent_tree(struct inode *inode)
+{
+ struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
+ struct extent_tree *et;
+
+ down_read(&sbi->extent_tree_lock);
+ et = radix_tree_lookup(&sbi->extent_tree_root, inode->i_ino);
+ if (!et) {
+ up_read(&sbi->extent_tree_lock);
+ goto out;
+ }
+ atomic_inc(&et->refcount);
+ up_read(&sbi->extent_tree_lock);
+
+ /* free all extent info belong to this extent tree */
+ write_lock(&et->lock);
+ __free_extent_tree(sbi, et, true);
+ write_unlock(&et->lock);
+
+ atomic_dec(&et->refcount);
+
+ /* try to find and delete extent tree entry in radix tree */
+ down_write(&sbi->extent_tree_lock);
+ et = radix_tree_lookup(&sbi->extent_tree_root, inode->i_ino);
+ if (!et) {
+ up_write(&sbi->extent_tree_lock);
+ goto out;
+ }
+ f2fs_bug_on(sbi, atomic_read(&et->refcount) || et->count);
+ radix_tree_delete(&sbi->extent_tree_root, inode->i_ino);
+ kmem_cache_free(extent_tree_slab, et);
+ sbi->total_ext_tree--;
+ up_write(&sbi->extent_tree_lock);
+out:
+ return;
+}
+
static bool f2fs_lookup_extent_cache(struct inode *inode, pgoff_t pgofs,
struct extent_info *ei)
{
@@ -1195,6 +1575,37 @@ static sector_t f2fs_bmap(struct address_space *mapping, sector_t block)
return generic_block_bmap(mapping, block, get_data_block);
}
+void init_extent_cache_info(struct f2fs_sb_info *sbi)
+{
+ INIT_RADIX_TREE(&sbi->extent_tree_root, GFP_NOIO);
+ init_rwsem(&sbi->extent_tree_lock);
+ INIT_LIST_HEAD(&sbi->extent_list);
+ spin_lock_init(&sbi->extent_lock);
+ sbi->total_ext_tree = 0;
+ atomic_set(&sbi->total_ext_node, 0);
+}
+
+int __init create_extent_cache(void)
+{
+ extent_tree_slab = f2fs_kmem_cache_create("f2fs_extent_tree",
+ sizeof(struct extent_tree));
+ if (!extent_tree_slab)
+ return -ENOMEM;
+ extent_node_slab = f2fs_kmem_cache_create("f2fs_extent_node",
+ sizeof(struct extent_node));
+ if (!extent_node_slab) {
+ kmem_cache_destroy(extent_tree_slab);
+ return -ENOMEM;
+ }
+ return 0;
+}
+
+void destroy_extent_cache(void)
+{
+ kmem_cache_destroy(extent_node_slab);
+ kmem_cache_destroy(extent_tree_slab);
+}
+
const struct address_space_operations f2fs_dblock_aops = {
.readpage = f2fs_read_data_page,
.readpages = f2fs_read_data_pages,
diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index 7c6c192..e184847 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -350,6 +350,33 @@ static inline void set_raw_extent(struct extent_info *ext,
i_ext->len = cpu_to_le32(ext->len);
}
+static inline void set_extent_info(struct extent_info *ei, unsigned int fofs,
+ u32 blk, unsigned int len)
+{
+ ei->fofs = fofs;
+ ei->blk = blk;
+ ei->len = len;
+}
+
+static inline bool __is_extent_mergeable(struct extent_info *back,
+ struct extent_info *front)
+{
+ return (back->fofs + back->len == front->fofs &&
+ back->blk + back->len == front->blk);
+}
+
+static inline bool __is_back_mergeable(struct extent_info *cur,
+ struct extent_info *back)
+{
+ return __is_extent_mergeable(back, cur);
+}
+
+static inline bool __is_front_mergeable(struct extent_info *cur,
+ struct extent_info *front)
+{
+ return __is_extent_mergeable(cur, front);
+}
+
struct f2fs_nm_info {
block_t nat_blkaddr; /* base disk address of NAT */
nid_t max_nid; /* maximum possible node ids */
diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c
index 9feda38..a1bc2e7 100644
--- a/fs/f2fs/node.c
+++ b/fs/f2fs/node.c
@@ -41,7 +41,9 @@ bool available_free_memory(struct f2fs_sb_info *sbi, int type)
/* only uses low memory */
avail_ram = val.totalram - val.totalhigh;
- /* give 25%, 25%, 50%, 50% memory for each components respectively */
+ /*
+ * give 25%, 25%, 50%, 50%, 50% memory for each components respectively
+ */
if (type == FREE_NIDS) {
mem_size = (nm_i->fcnt * sizeof(struct free_nid)) >>
PAGE_CACHE_SHIFT;
@@ -62,6 +64,11 @@ bool available_free_memory(struct f2fs_sb_info *sbi, int type)
mem_size += (sbi->im[i].ino_num *
sizeof(struct ino_entry)) >> PAGE_CACHE_SHIFT;
res = mem_size < ((avail_ram * nm_i->ram_thresh / 100) >> 1);
+ } else if (type == EXTENT_CACHE) {
+ mem_size = (sbi->total_ext_tree * sizeof(struct extent_tree) +
+ atomic_read(&sbi->total_ext_node) *
+ sizeof(struct extent_node)) >> PAGE_CACHE_SHIFT;
+ res = mem_size < ((avail_ram * nm_i->ram_thresh / 100) >> 1);
} else {
if (sbi->sb->s_bdi->dirty_exceeded)
return false;
--
2.2.1
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