ext4: prevent a fs with errors from being resized

A filesystem with errors is not allowed to being resized, otherwise,
it is easy to destroy the filesystem.
Signed-off-by: NYongqiang Yang <xiaoqiangnk@gmail.com>
Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>

fs/ext4/resize.c

@@ -23,6 +23,16 @@ int ext4_resize_begin(struct super_block *sb)
 	if (!capable(CAP_SYS_RESOURCE))
 		return -EPERM;
 
+	/*
+	 * We are not allowed to do online-resizing on a filesystem mounted
+	 * with error, because it can destroy the filesystem easily.
+	 */
+	if (EXT4_SB(sb)->s_mount_state & EXT4_ERROR_FS) {
+		ext4_warning(sb, "There are errors in the filesystem, "
+			     "so online resizing is not allowed\n");
+		return -EPERM;
+	}
+
 	if (test_and_set_bit_lock(EXT4_RESIZING, &EXT4_SB(sb)->s_resize_flags))
 		ret = -EBUSY;