f2fs: enable in-place-update for fdatasync

This patch enforces in-place-updates only when fdatasync is requested.
If we adopt this in-place-updates for the fdatasync, we can skip to write the
recovery information.

Reviewed-by: Chao Yu <chao2.yu@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
diff --git a/fs/f2fs/segment.h b/fs/f2fs/segment.h
index ee5c75e..55973f7 100644
--- a/fs/f2fs/segment.h
+++ b/fs/f2fs/segment.h
@@ -486,6 +486,10 @@
 	if (S_ISDIR(inode->i_mode))
 		return false;
 
+	/* this is only set during fdatasync */
+	if (is_inode_flag_set(F2FS_I(inode), FI_NEED_IPU))
+		return true;
+
 	switch (SM_I(sbi)->ipu_policy) {
 	case F2FS_IPU_FORCE:
 		return true;