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Date: Thu, 22 Jan 2015 17:48:03 -0800
From: Jaegeuk Kim <jaegeuk@...nel.org>
To: Chao Yu <chao2.yu@...sung.com>
Cc: Changman Lee <cm224.lee@...sung.com>,
linux-f2fs-devel@...ts.sourceforge.net,
linux-kernel@...r.kernel.org
Subject: Re: [f2fs-dev][RFC PATCH 06/10] f2fs: add core functions for rb-tree
extent cache
On Mon, Jan 12, 2015 at 03:14:48PM +0800, Chao Yu wrote:
> 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:
> * add a cached_ei into struct extent_tree for a quick recent cache.
> * register rb-based extent cache shrink with mm shrink interface.
> * disable dir inode's extent cache.
>
> Signed-off-by: Chao Yu <chao2.yu@...sung.com>
> Signed-off-by: Jaegeuk Kim <jaegeuk@...nel.org>
> Signed-off-by: Changman Lee <cm224.lee@...sung.com>
> ---
> fs/f2fs/data.c | 458 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
> fs/f2fs/node.c | 9 +-
> 2 files changed, 466 insertions(+), 1 deletion(-)
>
> diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
> index 4f5b871e..bf8c5eb 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;
> @@ -373,6 +376,430 @@ end_update:
> return need_update;
> }
>
> +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 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 bool __is_back_mergeable(struct extent_info *cur,
> + struct extent_info *back)
> +{
> + return __is_extent_mergeable(back, cur);
> +}
> +
> +static bool __is_front_mergeable(struct extent_info *cur,
> + struct extent_info *front)
> +{
> + return __is_extent_mergeable(cur, front);
> +}
How about declaring these four functions as inline ones and locating them
inside f2fs.h?
> +
> +static struct extent_node *__try_back_merge(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;
> + rb_erase(&prev->rb_node, &et->root);
> + et->count--;
> + return prev;
> + }
> + return NULL;
> +}
> +
> +static struct extent_node *__try_front_merge(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;
> + rb_erase(&next->rb_node, &et->root);
> + et->count--;
> + 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(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(et, en);
> + return en;
> + }
> + p = &(*p)->rb_right;
> + } else
> + f2fs_bug_on(F2FS_I_SB(inode), 1);
Coding style.
} else {
...
}
> + }
How about adding __attach_extent_node()?
{
> +
> + en = kmem_cache_alloc(extent_node_slab, GFP_ATOMIC);
en = f2fs_kmem_cache_alloc(.., GFP_ATOMIC);
> + en->ei = *ei;
> + INIT_LIST_HEAD(&en->list);
> +
> + rb_link_node(&en->rb_node, parent, p);
> + rb_insert_color(&en->rb_node, &et->root);
> + atomic_inc(&sbi->total_ext_node);
> + et->count++;
}
> +
> + return en;
> +}
> +
> +static struct extent_node *__remove_extent_tree(struct extent_tree *et,
> + unsigned int fofs)
This is __detach_extent_node()?
> +{
> + struct rb_node *p = et->root.rb_node;
> + struct extent_node *en;
> +
> + while (p) {
> + en = rb_entry(p, struct extent_node, rb_node);
> +
> + if (fofs < en->ei.fofs)
> + p = p->rb_left;
Coding style.
if () {
} else {
}
> + else if (fofs >= en->ei.fofs + en->ei.len)
> + p = p->rb_right;
> + else {
> + rb_erase(&en->rb_node, &et->root);
> + et->count--;
Add here?
atomic_dec(&sbi->total_ext_node);
> + return en;
> + }
> + }
> + return NULL;
> +}
> +
> +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)) {
> + rb_erase(node, &et->root);
> + kmem_cache_free(extent_node_slab, en);
> + atomic_dec(&sbi->total_ext_node);
> + et->count--;
> + }
> + 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 *pei;
> + struct extent_info ei;
> + unsigned int endofs;
> +
> + if (is_inode_flag_set(F2FS_I(inode), FI_NO_EXTENT))
> + return;
> +
> +retry:
> + down_write(&sbi->extent_tree_lock);
> + et = radix_tree_lookup(&sbi->extent_tree_root, ino);
> + if (!et) {
> + et = kmem_cache_alloc(extent_tree_slab, GFP_ATOMIC);
et = f2fs_kmem_cache_alloc(.., GFP_ATOMIC);
> + if (!et) {
> + up_write(&sbi->extent_tree_lock);
> + goto retry;
> + }
> + if (radix_tree_insert(&sbi->extent_tree_root, ino, et)) {
> + up_write(&sbi->extent_tree_lock);
> + kmem_cache_free(extent_tree_slab, et);
> + goto retry;
> + }
> + 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 exist extent info in cache */
existing
> + en = __remove_extent_tree(et, fofs);
en = __detach_extent_node();?
> + if (!en)
> + goto update_extent;
> +
> + pei = &en->ei;
> + /* 2. if extent can be split more, split and insert the left part */
> + if (pei->len > 1) {
> + /* insert left part of split extent into cache */
> + if (pei->fofs < fofs) {
> + set_extent_info(&ei, pei->fofs, pei->blk,
> + fofs - pei->fofs);
> + en1 = __insert_extent_tree(sbi, et, &ei, NULL);
> + }
> +
> + /* insert right part of split extent into cache */
> + endofs = pei->fofs + pei->len - 1;
> + if (endofs > fofs) {
> + set_extent_info(&ei, fofs + 1,
> + fofs - pei->fofs + pei->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_init(&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_list,
> + * but just waiting shrinker to free them for reclaiming when OOM.
> + */
Can we just remove en1 and en2 in __insert_extent_tree?
> + if (en1 && en1->ei.len >= F2FS_MIN_EXTENT_LEN)
> + list_add_tail(&en1->list, &sbi->extent_list);
> + if (en2 && en2->ei.len >= F2FS_MIN_EXTENT_LEN)
> + 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_init(&den->list);
> + spin_unlock(&sbi->extent_lock);
> +
> + if (en) {
> + kmem_cache_free(extent_node_slab, en);
> + atomic_dec(&sbi->total_ext_node);
--> move into __detach_extent_node().
> + }
> + if (den) {
> + kmem_cache_free(extent_node_slab, den);
> + atomic_dec(&sbi->total_ext_node);
> + }
> +
> + 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;
> + unsigned int node_cnt = 0, tree_cnt = 0;
> +
> + 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);
> + node_cnt += __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--;
> + tree_cnt++;
No use of tree_cnt.
Thanks,
> + }
> + }
> + 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;
> + unsigned int node_cnt = 0;
> +
> + 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);
> + node_cnt = __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)
> {
> @@ -1198,6 +1625,37 @@ 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_NOFS);
> + 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/node.c b/fs/f2fs/node.c
> index d7c1436..387017f 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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