f2fs: avoid potential unnecessary codes

This patch relocates some operations to avoid unnecessary execution.

Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c
index a7cb0db2..9bed016 100644
--- a/fs/f2fs/node.c
+++ b/fs/f2fs/node.c
@@ -348,7 +348,6 @@
 	struct nat_entry *e;
 	int i;
 
-	memset(&ne, 0, sizeof(struct f2fs_nat_entry));
 	ni->nid = nid;
 
 	/* Check nat cache */
@@ -363,6 +362,8 @@
 	if (e)
 		return;
 
+	memset(&ne, 0, sizeof(struct f2fs_nat_entry));
+
 	/* Check current segment summary */
 	mutex_lock(&curseg->curseg_mutex);
 	i = lookup_journal_in_cursum(sum, NAT_JOURNAL, nid, 0);