f2fs: use wait_for_stable_page to avoid contention

In write_begin, if storage supports stable_page, we don't need to wait for
writeback to update its contents.
This patch introduces to use wait_for_stable_page instead of
wait_on_page_writeback.

Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c
index aa3ca79..a004bc0 100644
--- a/fs/f2fs/node.c
+++ b/fs/f2fs/node.c
@@ -861,7 +861,7 @@
 				f2fs_put_page(page, 1);
 				goto restart;
 			}
-			f2fs_wait_on_page_writeback(page, NODE);
+			f2fs_wait_on_page_writeback(page, NODE, true);
 			ri->i_nid[offset[0] - NODE_DIR1_BLOCK] = 0;
 			set_page_dirty(page);
 			unlock_page(page);
@@ -976,7 +976,7 @@
 	new_ni.ino = dn->inode->i_ino;
 	set_node_addr(sbi, &new_ni, NEW_ADDR, false);
 
-	f2fs_wait_on_page_writeback(page, NODE);
+	f2fs_wait_on_page_writeback(page, NODE, true);
 	fill_node_footer(page, dn->nid, dn->inode->i_ino, ofs, true);
 	set_cold_node(dn->inode, page);
 	SetPageUptodate(page);
@@ -1328,7 +1328,7 @@
 				continue;
 
 			if (ino && ino_of_node(page) == ino) {
-				f2fs_wait_on_page_writeback(page, NODE);
+				f2fs_wait_on_page_writeback(page, NODE, true);
 				if (TestClearPageError(page))
 					ret = -EIO;
 			}
@@ -1367,7 +1367,7 @@
 	if (unlikely(f2fs_cp_error(sbi)))
 		goto redirty_out;
 
-	f2fs_wait_on_page_writeback(page, NODE);
+	f2fs_wait_on_page_writeback(page, NODE, true);
 
 	/* get old block addr of this node page */
 	nid = nid_of_node(page);
@@ -1744,7 +1744,7 @@
 	src_addr = inline_xattr_addr(page);
 	inline_size = inline_xattr_size(inode);
 
-	f2fs_wait_on_page_writeback(ipage, NODE);
+	f2fs_wait_on_page_writeback(ipage, NODE, true);
 	memcpy(dst_addr, src_addr, inline_size);
 update_inode:
 	update_inode(inode, ipage);