f2fs: fix to wait page writeback before update

Filesystem including f2fs should support stable page for special
device like software raid, however there is one missing path that
page could be updated while it is writeback state as below, fix
this.

- gc_node_segment
 - f2fs_move_node_page
  - __write_node_page
   - set_page_writeback

- do_read_inode
 - f2fs_init_extent_tree
  - __f2fs_init_extent_tree
    i_ext->len = 0;
Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

fs/f2fs/extent_cache.c

@@ -325,9 +325,10 @@ static void __drop_largest_extent(struct extent_tree *et,
 }
 
 /* return true, if inode page is changed */
-static bool __f2fs_init_extent_tree(struct inode *inode, struct f2fs_extent *i_ext)
+static void __f2fs_init_extent_tree(struct inode *inode, struct page *ipage)
 {
 	struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
+	struct f2fs_extent *i_ext = ipage ? &F2FS_INODE(ipage)->i_ext : NULL;
 	struct extent_tree *et;
 	struct extent_node *en;
 	struct extent_info ei;
@@ -335,16 +336,18 @@ static bool __f2fs_init_extent_tree(struct inode *inode, struct f2fs_extent *i_e
 	if (!f2fs_may_extent_tree(inode)) {
 		/* drop largest extent */
 		if (i_ext && i_ext->len) {
+			f2fs_wait_on_page_writeback(ipage, NODE, true, true);
 			i_ext->len = 0;
-			return true;
+			set_page_dirty(ipage);
+			return;
 		}
-		return false;
+		return;
 	}
 
 	et = __grab_extent_tree(inode);
 
 	if (!i_ext || !i_ext->len)
-		return false;
+		return;
 
 	get_extent_info(&ei, i_ext);
 
@@ -360,17 +363,14 @@ static bool __f2fs_init_extent_tree(struct inode *inode, struct f2fs_extent *i_e
 	}
 out:
 	write_unlock(&et->lock);
-	return false;
 }
 
-bool f2fs_init_extent_tree(struct inode *inode, struct f2fs_extent *i_ext)
+void f2fs_init_extent_tree(struct inode *inode, struct page *ipage)
 {
-	bool ret =  __f2fs_init_extent_tree(inode, i_ext);
+	__f2fs_init_extent_tree(inode, ipage);
 
 	if (!F2FS_I(inode)->extent_tree)
 		set_inode_flag(inode, FI_NO_EXTENT);
-
-	return ret;
 }
 
 static bool f2fs_lookup_extent_tree(struct inode *inode, pgoff_t pgofs,

fs/f2fs/f2fs.h

@@ -3798,7 +3798,7 @@ struct rb_entry *f2fs_lookup_rb_tree_ret(struct rb_root_cached *root,
 bool f2fs_check_rb_tree_consistence(struct f2fs_sb_info *sbi,
 						struct rb_root_cached *root);
 unsigned int f2fs_shrink_extent_tree(struct f2fs_sb_info *sbi, int nr_shrink);
-bool f2fs_init_extent_tree(struct inode *inode, struct f2fs_extent *i_ext);
+void f2fs_init_extent_tree(struct inode *inode, struct page *ipage);
 void f2fs_drop_extent_tree(struct inode *inode);
 unsigned int f2fs_destroy_extent_node(struct inode *inode);
 void f2fs_destroy_extent_tree(struct inode *inode);

fs/f2fs/inode.c

@@ -367,8 +367,7 @@ static int do_read_inode(struct inode *inode)
 	fi->i_pino = le32_to_cpu(ri->i_pino);
 	fi->i_dir_level = ri->i_dir_level;
 
-	if (f2fs_init_extent_tree(inode, &ri->i_ext))
-		set_page_dirty(node_page);
+	f2fs_init_extent_tree(inode, node_page);
 
 	get_inline_info(inode, ri);