Date:   Tue, 6 Dec 2022 11:05:46 -0800
From:   Jaegeuk Kim <jaegeuk@...nel.org>
To:     linux-kernel@...r.kernel.org,
        linux-f2fs-devel@...ts.sourceforge.net
Subject: Re: [PATCH 4/6 v2] f2fs: refactor extent_cache to support for read
 and more

This patch prepares extent_cache to get more use-cases.

Signed-off-by: Jaegeuk Kim <jaegeuk@...nel.org>
---

 Change log from v1:
  - fix a bug

 fs/f2fs/data.c         | 14 +++----
 fs/f2fs/debug.c        | 53 +++++++++++++++++---------
 fs/f2fs/extent_cache.c | 85 +++++++++++++++++++++++++++---------------
 3 files changed, 97 insertions(+), 55 deletions(-)

diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
index 35c19248b1e2..031fa27d194e 100644
--- a/fs/f2fs/data.c
+++ b/fs/f2fs/data.c
@@ -1195,7 +1195,7 @@ int f2fs_get_block(struct dnode_of_data *dn, pgoff_t index)
 	struct extent_info ei = {0, };
 	struct inode *inode = dn->inode;
 
-	if (f2fs_lookup_extent_cache(inode, index, &ei)) {
+	if (f2fs_lookup_extent_cache(inode, index, &ei, EX_READ)) {
 		dn->data_blkaddr = ei.blk + index - ei.fofs;
 		return 0;
 	}
@@ -1217,7 +1217,7 @@ struct page *f2fs_get_read_data_page(struct inode *inode, pgoff_t index,
 	if (!page)
 		return ERR_PTR(-ENOMEM);
 
-	if (f2fs_lookup_extent_cache(inode, index, &ei)) {
+	if (f2fs_lookup_extent_cache(inode, index, &ei, EX_READ)) {
 		dn.data_blkaddr = ei.blk + index - ei.fofs;
 		if (!f2fs_is_valid_blkaddr(F2FS_I_SB(inode), dn.data_blkaddr,
 						DATA_GENERIC_ENHANCE_READ)) {
@@ -1485,7 +1485,7 @@ int f2fs_map_blocks(struct inode *inode, struct f2fs_map_blocks *map,
 	pgofs =	(pgoff_t)map->m_lblk;
 	end = pgofs + maxblocks;
 
-	if (!create && f2fs_lookup_extent_cache(inode, pgofs, &ei)) {
+	if (!create && f2fs_lookup_extent_cache(inode, pgofs, &ei, EX_READ)) {
 		if (f2fs_lfs_mode(sbi) && flag == F2FS_GET_BLOCK_DIO &&
 							map->m_may_create)
 			goto next_dnode;
@@ -2201,7 +2201,7 @@ int f2fs_read_multi_pages(struct compress_ctx *cc, struct bio **bio_ret,
 	if (f2fs_cluster_is_empty(cc))
 		goto out;
 
-	if (f2fs_lookup_extent_cache(inode, start_idx, &ei))
+	if (f2fs_lookup_extent_cache(inode, start_idx, &ei, EX_READ))
 		from_dnode = false;
 
 	if (!from_dnode)
@@ -2635,7 +2635,7 @@ int f2fs_do_write_data_page(struct f2fs_io_info *fio)
 		set_new_dnode(&dn, inode, NULL, NULL, 0);
 
 	if (need_inplace_update(fio) &&
-			f2fs_lookup_extent_cache(inode, page->index, &ei)) {
+	    f2fs_lookup_extent_cache(inode, page->index, &ei, EX_READ)) {
 		fio->old_blkaddr = ei.blk + page->index - ei.fofs;
 
 		if (!f2fs_is_valid_blkaddr(fio->sbi, fio->old_blkaddr,
@@ -3359,7 +3359,7 @@ static int prepare_write_begin(struct f2fs_sb_info *sbi,
 	} else if (locked) {
 		err = f2fs_get_block(&dn, index);
 	} else {
-		if (f2fs_lookup_extent_cache(inode, index, &ei)) {
+		if (f2fs_lookup_extent_cache(inode, index, &ei, EX_READ)) {
 			dn.data_blkaddr = ei.blk + index - ei.fofs;
 		} else {
 			/* hole case */
@@ -3400,7 +3400,7 @@ static int __find_data_block(struct inode *inode, pgoff_t index,
 
 	set_new_dnode(&dn, inode, ipage, ipage, 0);
 
-	if (f2fs_lookup_extent_cache(inode, index, &ei)) {
+	if (f2fs_lookup_extent_cache(inode, index, &ei, EX_READ)) {
 		dn.data_blkaddr = ei.blk + index - ei.fofs;
 	} else {
 		/* hole case */
diff --git a/fs/f2fs/debug.c b/fs/f2fs/debug.c
index a216dcdf6941..71eb4c50edf6 100644
--- a/fs/f2fs/debug.c
+++ b/fs/f2fs/debug.c
@@ -72,15 +72,23 @@ static void update_general_status(struct f2fs_sb_info *sbi)
 	si->main_area_zones = si->main_area_sections /
 				le32_to_cpu(raw_super->secs_per_zone);
 
-	/* validation check of the segment numbers */
+	/* general extent cache stats */
+	for (i = 0; i < NR_EXTENT_CACHES; i++) {
+		struct extent_tree_info *eti = &sbi->extent_tree[i];
+
+		si->hit_cached[i] = atomic64_read(&sbi->read_hit_cached[i]);
+		si->hit_rbtree[i] = atomic64_read(&sbi->read_hit_rbtree[i]);
+		si->total_ext[i] = atomic64_read(&sbi->total_hit_ext[i]);
+		si->hit_total[i] = si->hit_cached[i] + si->hit_rbtree[i];
+		si->ext_tree[i] = atomic_read(&eti->total_ext_tree);
+		si->zombie_tree[i] = atomic_read(&eti->total_zombie_tree);
+		si->ext_node[i] = atomic_read(&eti->total_ext_node);
+	}
+	/* read extent_cache only */
 	si->hit_largest = atomic64_read(&sbi->read_hit_largest);
-	si->hit_cached = atomic64_read(&sbi->read_hit_cached);
-	si->hit_rbtree = atomic64_read(&sbi->read_hit_rbtree);
-	si->hit_total = si->hit_largest + si->hit_cached + si->hit_rbtree;
-	si->total_ext = atomic64_read(&sbi->total_hit_ext);
-	si->ext_tree = atomic_read(&sbi->total_ext_tree);
-	si->zombie_tree = atomic_read(&sbi->total_zombie_tree);
-	si->ext_node = atomic_read(&sbi->total_ext_node);
+	si->hit_total[EX_READ] += si->hit_largest;
+
+	/* validation check of the segment numbers */
 	si->ndirty_node = get_pages(sbi, F2FS_DIRTY_NODES);
 	si->ndirty_dent = get_pages(sbi, F2FS_DIRTY_DENTS);
 	si->ndirty_meta = get_pages(sbi, F2FS_DIRTY_META);
@@ -294,10 +302,16 @@ static void update_mem_info(struct f2fs_sb_info *sbi)
 				sizeof(struct nat_entry_set);
 	for (i = 0; i < MAX_INO_ENTRY; i++)
 		si->cache_mem += sbi->im[i].ino_num * sizeof(struct ino_entry);
-	si->cache_mem += atomic_read(&sbi->total_ext_tree) *
+
+	for (i = 0; i < NR_EXTENT_CACHES; i++) {
+		struct extent_tree_info *eti = &sbi->extent_tree[i];
+
+		si->ext_mem[i] += atomic_read(&eti->total_ext_tree) *
 						sizeof(struct extent_tree);
-	si->cache_mem += atomic_read(&sbi->total_ext_node) *
+		si->ext_mem[i] += atomic_read(&eti->total_ext_node) *
 						sizeof(struct extent_node);
+		si->cache_mem += si->ext_mem[i];
+	}
 
 	si->page_mem = 0;
 	if (sbi->node_inode) {
@@ -490,16 +504,19 @@ static int stat_show(struct seq_file *s, void *v)
 				si->bg_node_blks);
 		seq_printf(s, "BG skip : IO: %u, Other: %u\n",
 				si->io_skip_bggc, si->other_skip_bggc);
-		seq_puts(s, "\nExtent Cache:\n");
+		seq_puts(s, "\nExtent Cache (Read):\n");
 		seq_printf(s, "  - Hit Count: L1-1:%llu L1-2:%llu L2:%llu\n",
 				si->hit_largest, si->hit_cached,
-				si->hit_rbtree);
+				si->hit_largest, si->hit_cached[EX_READ],
+				si->hit_rbtree[EX_READ]);
 		seq_printf(s, "  - Hit Ratio: %llu%% (%llu / %llu)\n",
-				!si->total_ext ? 0 :
-				div64_u64(si->hit_total * 100, si->total_ext),
-				si->hit_total, si->total_ext);
+				!si->total_ext[EX_READ] ? 0 :
+				div64_u64(si->hit_total[EX_READ] * 100,
+				si->total_ext[EX_READ]),
+				si->hit_total[EX_READ], si->total_ext[EX_READ]);
 		seq_printf(s, "  - Inner Struct Count: tree: %d(%d), node: %d\n",
-				si->ext_tree, si->zombie_tree, si->ext_node);
+				si->ext_tree[EX_READ], si->zombie_tree[EX_READ],
+				si->ext_node[EX_READ]);
 		seq_puts(s, "\nBalancing F2FS Async:\n");
 		seq_printf(s, "  - DIO (R: %4d, W: %4d)\n",
 			   si->nr_dio_read, si->nr_dio_write);
@@ -566,8 +583,10 @@ static int stat_show(struct seq_file *s, void *v)
 			(si->base_mem + si->cache_mem + si->page_mem) >> 10);
 		seq_printf(s, "  - static: %llu KB\n",
 				si->base_mem >> 10);
-		seq_printf(s, "  - cached: %llu KB\n",
+		seq_printf(s, "  - cached all: %llu KB\n",
 				si->cache_mem >> 10);
+		seq_printf(s, "  - read extent cache: %llu KB\n",
+				si->ext_mem[EX_READ] >> 10);
 		seq_printf(s, "  - paged : %llu KB\n",
 				si->page_mem >> 10);
 	}
diff --git a/fs/f2fs/extent_cache.c b/fs/f2fs/extent_cache.c
index 22a51934cd45..46dbe3629245 100644
--- a/fs/f2fs/extent_cache.c
+++ b/fs/f2fs/extent_cache.c
@@ -15,7 +15,21 @@
 #include "node.h"
 #include <trace/events/f2fs.h>
 
-static bool f2fs_may_extent_tree(struct inode *inode)
+static bool f2fs_may_read_extent_tree(struct inode *inode)
+{
+	struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
+
+	if (!test_opt(sbi, READ_EXTENT_CACHE))
+		return false;
+	if (is_inode_flag_set(inode, FI_NO_EXTENT))
+		return false;
+	if (is_inode_flag_set(inode, FI_COMPRESSED_FILE) &&
+			 !f2fs_sb_has_readonly(sbi))
+		return false;
+	return S_ISREG(inode->i_mode);
+}
+
+static bool f2fs_may_extent_tree(struct inode *inode, enum extent_type type)
 {
 	struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
 
@@ -26,18 +40,16 @@ static bool f2fs_may_extent_tree(struct inode *inode)
 	if (list_empty(&sbi->s_list))
 		return false;
 
-	if (!test_opt(sbi, READ_EXTENT_CACHE) ||
-			is_inode_flag_set(inode, FI_NO_EXTENT) ||
-			(is_inode_flag_set(inode, FI_COMPRESSED_FILE) &&
-			 !f2fs_sb_has_readonly(sbi)))
-		return false;
-
-	return S_ISREG(inode->i_mode);
+	if (type == EX_READ)
+		return f2fs_may_read_extent_tree(inode);
+	return false;
 }
 
 static void __try_update_largest_extent(struct extent_tree *et,
 						struct extent_node *en)
 {
+	if (et->type != EX_READ)
+		return;
 	if (en->ei.len <= et->largest.len)
 		return;
 
@@ -46,28 +58,31 @@ static void __try_update_largest_extent(struct extent_tree *et,
 }
 
 static bool __is_extent_mergeable(struct extent_info *back,
-				struct extent_info *front)
+		struct extent_info *front, enum extent_type type)
 {
+	if (type == EX_READ) {
 #ifdef CONFIG_F2FS_FS_COMPRESSION
-	if (back->c_len && back->len != back->c_len)
-		return false;
-	if (front->c_len && front->len != front->c_len)
-		return false;
+		if (back->c_len && back->len != back->c_len)
+			return false;
+		if (front->c_len && front->len != front->c_len)
+			return false;
 #endif
-	return (back->fofs + back->len == front->fofs &&
-			back->blk + back->len == front->blk);
+		return (back->fofs + back->len == front->fofs &&
+				back->blk + back->len == front->blk);
+	}
+	return false;
 }
 
 static bool __is_back_mergeable(struct extent_info *cur,
-				struct extent_info *back)
+		struct extent_info *back, enum extent_type type)
 {
-	return __is_extent_mergeable(back, cur);
+	return __is_extent_mergeable(back, cur, type);
 }
 
 static bool __is_front_mergeable(struct extent_info *cur,
-				struct extent_info *front)
+		struct extent_info *front, enum extent_type type)
 {
-	return __is_extent_mergeable(cur, front);
+	return __is_extent_mergeable(cur, front, type);
 }
 
 static struct rb_entry *__lookup_rb_tree_fast(struct rb_entry *cached_re,
@@ -292,6 +307,7 @@ static struct extent_node *__attach_extent_node(struct f2fs_sb_info *sbi,
 				struct rb_node *parent, struct rb_node **p,
 				bool leftmost)
 {
+	struct extent_tree_info *eti = &sbi->extent_tree[et->type];
 	struct extent_node *en;
 
 	en = f2fs_kmem_cache_alloc(extent_node_slab, GFP_ATOMIC, false, sbi);
@@ -305,16 +321,18 @@ static struct extent_node *__attach_extent_node(struct f2fs_sb_info *sbi,
 	rb_link_node(&en->rb_node, parent, p);
 	rb_insert_color_cached(&en->rb_node, &et->root, leftmost);
 	atomic_inc(&et->node_cnt);
-	atomic_inc(&sbi->total_ext_node);
+	atomic_inc(&eti->total_ext_node);
 	return en;
 }
 
 static void __detach_extent_node(struct f2fs_sb_info *sbi,
 				struct extent_tree *et, struct extent_node *en)
 {
+	struct extent_tree_info *eti = &sbi->extent_tree[et->type];
+
 	rb_erase_cached(&en->rb_node, &et->root);
 	atomic_dec(&et->node_cnt);
-	atomic_dec(&sbi->total_ext_node);
+	atomic_dec(&eti->total_ext_node);
 
 	if (et->cached_en == en)
 		et->cached_en = NULL;
@@ -330,42 +348,47 @@ static void __detach_extent_node(struct f2fs_sb_info *sbi,
 static void __release_extent_node(struct f2fs_sb_info *sbi,
 			struct extent_tree *et, struct extent_node *en)
 {
-	spin_lock(&sbi->extent_lock);
+	struct extent_tree_info *eti = &sbi->extent_tree[et->type];
+
+	spin_lock(&eti->extent_lock);
 	f2fs_bug_on(sbi, list_empty(&en->list));
 	list_del_init(&en->list);
-	spin_unlock(&sbi->extent_lock);
+	spin_unlock(&eti->extent_lock);
 
 	__detach_extent_node(sbi, et, en);
 }
 
-static struct extent_tree *__grab_extent_tree(struct inode *inode)
+static struct extent_tree *__grab_extent_tree(struct inode *inode,
+						enum extent_type type)
 {
 	struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
+	struct extent_tree_info *eti = &sbi->extent_tree[type];
 	struct extent_tree *et;
 	nid_t ino = inode->i_ino;
 
-	mutex_lock(&sbi->extent_tree_lock);
-	et = radix_tree_lookup(&sbi->extent_tree_root, ino);
+	mutex_lock(&eti->extent_tree_lock);
+	et = radix_tree_lookup(&eti->extent_tree_root, ino);
 	if (!et) {
 		et = f2fs_kmem_cache_alloc(extent_tree_slab,
 					GFP_NOFS, true, NULL);
-		f2fs_radix_tree_insert(&sbi->extent_tree_root, ino, et);
+		f2fs_radix_tree_insert(&eti->extent_tree_root, ino, et);
 		memset(et, 0, sizeof(struct extent_tree));
 		et->ino = ino;
+		et->type = type;
 		et->root = RB_ROOT_CACHED;
 		et->cached_en = NULL;
 		rwlock_init(&et->lock);
 		INIT_LIST_HEAD(&et->list);
 		atomic_set(&et->node_cnt, 0);
-		atomic_inc(&sbi->total_ext_tree);
+		atomic_inc(&eti->total_ext_tree);
 	} else {
-		atomic_dec(&sbi->total_zombie_tree);
+		atomic_dec(&eti->total_zombie_tree);
 		list_del_init(&et->list);
 	}
-	mutex_unlock(&sbi->extent_tree_lock);
+	mutex_unlock(&eti->extent_tree_lock);
 
 	/* never died until evict_inode */
-	F2FS_I(inode)->extent_tree = et;
+	F2FS_I(inode)->extent_tree[type] = et;
 
 	return et;
 }
-- 
2.38.1.584.g0f3c55d4c2-goog

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