f2fs: preserve extent info for extent cache

This patch tries to preserve last extent info in extent tree cache into on-disk
inode, so this can help us to reuse the last extent info next time for
performance.

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

3 files changed, 62 insertions, 0 deletions

diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
index e3be4be3a6d8..8a940e518be8 100644
--- a/fs/f2fs/data.c
+++ b/fs/f2fs/data.c
@@ -719,6 +719,55 @@ update_extent:
         atomic_dec(&et->refcount);
 }
 
+void f2fs_preserve_extent_tree(struct inode *inode)
+{
+        struct extent_tree *et;
+        struct extent_info *ext = &F2FS_I(inode)->ext;
+        bool sync = false;
+
+        if (!test_opt(F2FS_I_SB(inode), EXTENT_CACHE))
+                return;
+
+        et = __find_extent_tree(F2FS_I_SB(inode), inode->i_ino);
+        if (!et) {
+                if (ext->len) {
+                        ext->len = 0;
+                        update_inode_page(inode);
+                }
+                return;
+        }
+
+        read_lock(&et->lock);
+        if (et->count) {
+                struct extent_node *en;
+
+                if (et->cached_en) {
+                        en = et->cached_en;
+                } else {
+                        struct rb_node *node = rb_first(&et->root);
+
+                        if (!node)
+                                node = rb_last(&et->root);
+                        en = rb_entry(node, struct extent_node, rb_node);
+                }
+
+                if (__is_extent_same(ext, &en->ei))
+                        goto out;
+
+                *ext = en->ei;
+                sync = true;
+        } else if (ext->len) {
+                ext->len = 0;
+                sync = true;
+        }
+out:
+        read_unlock(&et->lock);
+        atomic_dec(&et->refcount);
+
+        if (sync)
+                update_inode_page(inode);
+}
+
 void f2fs_shrink_extent_tree(struct f2fs_sb_info *sbi, int nr_shrink)
 {
         struct extent_tree *treevec[EXT_TREE_VEC_SIZE];
diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index 431b4af693e5..0be198339c3b 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -371,6 +371,13 @@ static inline void set_extent_info(struct extent_info *ei, unsigned int fofs,
         ei->len = len;
 }
 
+static inline bool __is_extent_same(struct extent_info *ei1,
+                                                struct extent_info *ei2)
+{
+        return (ei1->fofs == ei2->fofs && ei1->blk == ei2->blk &&
+                                                ei1->len == ei2->len);
+}
+
 static inline bool __is_extent_mergeable(struct extent_info *back,
                                                 struct extent_info *front)
 {
@@ -1598,6 +1605,7 @@ void f2fs_shrink_extent_tree(struct f2fs_sb_info *, int);
 void f2fs_destroy_extent_tree(struct inode *);
 void f2fs_init_extent_cache(struct inode *, struct f2fs_extent *);
 void f2fs_update_extent_cache(struct dnode_of_data *);
+void f2fs_preserve_extent_tree(struct inode *);
 struct page *find_data_page(struct inode *, pgoff_t, bool);
 struct page *get_lock_data_page(struct inode *, pgoff_t);
 struct page *get_new_data_page(struct inode *, struct page *, pgoff_t, bool);
diff --git a/fs/f2fs/inode.c b/fs/f2fs/inode.c
index 9e64d3efb2d2..07237ac2935e 100644
--- a/fs/f2fs/inode.c
+++ b/fs/f2fs/inode.c
@@ -343,7 +343,12 @@ void f2fs_evict_inode(struct inode *inode)
 no_delete:
         stat_dec_inline_dir(inode);
         stat_dec_inline_inode(inode);
+
+        /* update extent info in inode */
+        if (inode->i_nlink)
+                f2fs_preserve_extent_tree(inode);
         f2fs_destroy_extent_tree(inode);
+
         invalidate_mapping_pages(NODE_MAPPING(sbi), inode->i_ino, inode->i_ino);
         if (xnid)
                 invalidate_mapping_pages(NODE_MAPPING(sbi), xnid, xnid);