f2fs: avoid infinite loop at cp_error

This patch avoids an infinite loop in sync_dirty_inode_page when -EIO was
detected.

Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
diff --git a/fs/f2fs/checkpoint.c b/fs/f2fs/checkpoint.c
index dd10a03..ca514d5 100644
--- a/fs/f2fs/checkpoint.c
+++ b/fs/f2fs/checkpoint.c
@@ -731,6 +731,9 @@
 	struct dir_inode_entry *entry;
 	struct inode *inode;
 retry:
+	if (unlikely(f2fs_cp_error(sbi)))
+		return;
+
 	spin_lock(&sbi->dir_inode_lock);
 
 	head = &sbi->dir_inode_list;