f2fs: merge {invalidate,release}page for meta/node/data pages

This patch merges ->{invalidate,release}page function for meta/node/data pages.

After this, duplication of codes could be removed.

Signed-off-by: Chao Yu <chao2.yu@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
diff --git a/fs/f2fs/checkpoint.c b/fs/f2fs/checkpoint.c
index 470fa58..31a715b5 100644
--- a/fs/f2fs/checkpoint.c
+++ b/fs/f2fs/checkpoint.c
@@ -309,32 +309,12 @@
 	return 0;
 }
 
-static void f2fs_invalidate_meta_page(struct page *page, unsigned int offset,
-				      unsigned int length)
-{
-	struct inode *inode = page->mapping->host;
-
-	if (PageDirty(page))
-		dec_page_count(F2FS_I_SB(inode), F2FS_DIRTY_META);
-	ClearPagePrivate(page);
-}
-
-static int f2fs_release_meta_page(struct page *page, gfp_t wait)
-{
-	/* If this is dirty page, keep PagePrivate */
-	if (PageDirty(page))
-		return 0;
-
-	ClearPagePrivate(page);
-	return 1;
-}
-
 const struct address_space_operations f2fs_meta_aops = {
 	.writepage	= f2fs_write_meta_page,
 	.writepages	= f2fs_write_meta_pages,
 	.set_page_dirty	= f2fs_set_meta_page_dirty,
-	.invalidatepage = f2fs_invalidate_meta_page,
-	.releasepage	= f2fs_release_meta_page,
+	.invalidatepage = f2fs_invalidate_page,
+	.releasepage	= f2fs_release_page,
 };
 
 static void __add_ino_entry(struct f2fs_sb_info *sbi, nid_t ino, int type)