f2fs: improve shrink performance of extent nodes

On the worst case, we need to scan the whole radix tree and every rb-tree to
free the victimed extent_nodes when shrinking.

Pengyang initially introduced a victim_list to record the victimed extent_nodes,
and free these extent_nodes by just scanning a list.

Later, Chao Yu enhances the original patch to improve memory footprint by
removing victim list.

The policy of lru list shrinking becomes:
1) lock lru list's lock
2) trylock extent tree's lock
3) remove extent node from lru list
4) unlock lru list's lock
5) do shrink
6) repeat 1) to 5)

Signed-off-by: Hou Pengyang <houpengyang@huawei.com>
Signed-off-by: Chao Yu <chao2.yu@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

diff --git a/fs/f2fs/extent_cache.c b/fs/f2fs/extent_cache.c
index aae99f2a4345794fc9bcdfa94d354c38ffccc268..53f49f71332316e348d986de5463c7a26ae4bd2b 100644 (file)
--- a/fs/f2fs/extent_cache.c
+++ b/fs/f2fs/extent_cache.c
@@ -33,6 +33,7 @@ static struct extent_node *__attach_extent_node(struct f2fs_sb_info *sbi,
 
        en->ei = *ei;
        INIT_LIST_HEAD(&en->list);
+       en->et = et;
 
        rb_link_node(&en->rb_node, parent, p);
        rb_insert_color(&en->rb_node, &et->root);
@@ -63,8 +64,8 @@ static void __release_extent_node(struct f2fs_sb_info *sbi,
                        struct extent_tree *et, struct extent_node *en)
 {
        spin_lock(&sbi->extent_lock);
-       if (!list_empty(&en->list))
-               list_del_init(&en->list);
+       f2fs_bug_on(sbi, list_empty(&en->list));
+       list_del_init(&en->list);
        spin_unlock(&sbi->extent_lock);
 
        __detach_extent_node(sbi, et, en);
@@ -147,7 +148,7 @@ static struct extent_node *__init_extent_tree(struct f2fs_sb_info *sbi,
 }
 
 static unsigned int __free_extent_tree(struct f2fs_sb_info *sbi,
-                                       struct extent_tree *et, bool free_all)
+                                       struct extent_tree *et)
 {
        struct rb_node *node, *next;
        struct extent_node *en;
@@ -157,11 +158,7 @@ static unsigned int __free_extent_tree(struct f2fs_sb_info *sbi,
        while (node) {
                next = rb_next(node);
                en = rb_entry(node, struct extent_node, rb_node);
-
-               if (free_all)
-                       __release_extent_node(sbi, et, en);
-               else if (list_empty(&en->list))
-                       __detach_extent_node(sbi, et, en);
+               __release_extent_node(sbi, et, en);
                node = next;
        }
 
@@ -532,7 +529,7 @@ static unsigned int f2fs_update_extent_tree_range(struct inode *inode,
        }
 
        if (is_inode_flag_set(F2FS_I(inode), FI_NO_EXTENT))
-               __free_extent_tree(sbi, et, true);
+               __free_extent_tree(sbi, et);
 
        write_unlock(&et->lock);
 
@@ -541,14 +538,10 @@ static unsigned int f2fs_update_extent_tree_range(struct inode *inode,
 
 unsigned int f2fs_shrink_extent_tree(struct f2fs_sb_info *sbi, int nr_shrink)
 {
-       struct extent_tree *treevec[EXT_TREE_VEC_SIZE];
        struct extent_tree *et, *next;
-       struct extent_node *en, *tmp;
-       unsigned long ino = F2FS_ROOT_INO(sbi);
-       unsigned int found;
+       struct extent_node *en;
        unsigned int node_cnt = 0, tree_cnt = 0;
        int remained;
-       bool do_free = false;
 
        if (!test_opt(sbi, EXTENT_CACHE))
                return 0;
@@ -563,10 +556,10 @@ unsigned int f2fs_shrink_extent_tree(struct f2fs_sb_info *sbi, int nr_shrink)
        list_for_each_entry_safe(et, next, &sbi->zombie_list, list) {
                if (atomic_read(&et->node_cnt)) {
                        write_lock(&et->lock);
-                       node_cnt += __free_extent_tree(sbi, et, true);
+                       node_cnt += __free_extent_tree(sbi, et);
                        write_unlock(&et->lock);
                }
-
+               f2fs_bug_on(sbi, atomic_read(&et->node_cnt));
                list_del_init(&et->list);
                radix_tree_delete(&sbi->extent_tree_root, et->ino);
                kmem_cache_free(extent_tree_slab, et);
@@ -587,42 +580,29 @@ free_node:
        remained = nr_shrink - (node_cnt + tree_cnt);
 
        spin_lock(&sbi->extent_lock);
-       list_for_each_entry_safe(en, tmp, &sbi->extent_list, list) {
-               if (!remained--)
+       for (; remained > 0; remained--) {
+               if (list_empty(&sbi->extent_list))
                        break;
-               list_del_init(&en->list);
-               do_free = true;
-       }
-       spin_unlock(&sbi->extent_lock);
-
-       if (do_free == false)
-               goto unlock_out;
-
-       /*
-        * reset ino for searching victims from beginning of global extent tree.
-        */
-       ino = F2FS_ROOT_INO(sbi);
-
-       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];
+               en = list_first_entry(&sbi->extent_list,
+                                       struct extent_node, list);
+               et = en->et;
+               if (!write_trylock(&et->lock)) {
+                       /* refresh this extent node's position in extent list */
+                       list_move_tail(&en->list, &sbi->extent_list);
+                       continue;
+               }
 
-                       if (!atomic_read(&et->node_cnt))
-                               continue;
+               list_del_init(&en->list);
+               spin_unlock(&sbi->extent_lock);
 
-                       if (write_trylock(&et->lock)) {
-                               node_cnt += __free_extent_tree(sbi, et, false);
-                               write_unlock(&et->lock);
-                       }
+               __detach_extent_node(sbi, et, en);
 
-                       if (node_cnt + tree_cnt >= nr_shrink)
-                               goto unlock_out;
-               }
+               write_unlock(&et->lock);
+               node_cnt++;
+               spin_lock(&sbi->extent_lock);
        }
+       spin_unlock(&sbi->extent_lock);
+
 unlock_out:
        up_write(&sbi->extent_tree_lock);
 out:
@@ -641,7 +621,7 @@ unsigned int f2fs_destroy_extent_node(struct inode *inode)
                return 0;
 
        write_lock(&et->lock);
-       node_cnt = __free_extent_tree(sbi, et, true);
+       node_cnt = __free_extent_tree(sbi, et);
        write_unlock(&et->lock);
 
        return node_cnt;

diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index c4e723b9993050433323ac7d7f0a1cf67bf3d144..4e7eab9f3f5afdf61cad38c7724b8a500268b17f 100644 (file)
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -354,6 +354,7 @@ struct extent_node {
        struct rb_node rb_node;         /* rb node located in rb-tree */
        struct list_head list;          /* node in global extent list of sbi */
        struct extent_info ei;          /* extent info */
+       struct extent_tree *et;         /* extent tree pointer */
 };
 
 struct extent_tree {