f2fs: allocate node blocks for atomic write block replacement

When a node block is missing for atomic write block replacement, we need
to allocate it in advance of the replacement.
Signed-off-by: Daeho Jeong <daehojeong@google.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

fs/f2fs/segment.c

@@ -217,7 +217,7 @@ static int __replace_atomic_write_block(struct inode *inode, pgoff_t index,
 
 retry:
 	set_new_dnode(&dn, inode, NULL, NULL, 0);
-	err = f2fs_get_dnode_of_data(&dn, index, LOOKUP_NODE_RA);
+	err = f2fs_get_dnode_of_data(&dn, index, ALLOC_NODE);
 	if (err) {
 		if (err == -ENOMEM) {
 			f2fs_io_schedule_timeout(DEFAULT_IO_TIMEOUT);