jbd2: fix infinite loop when recovering corrupt journal blocks

When recovering the journal, don't fall into an infinite loop if we
encounter a corrupt journal block. Instead, just skip the block and
return an error, which fails the mount and thus forces the user to run
a full filesystem fsck.

Signed-off-by: Darrick J. Wong <[e-mail]>
Signed-off-by: Theodore Ts'o <[e-mail]>
Cc: [e-mail]

fs/jbd2/recovery.c

···
 	int			tag_bytes = journal_tag_bytes(journal);
 	__u32			crc32_sum = ~0; /* Transactional Checksums */
 	int			descr_csum_size = 0;
+	int			block_error = 0;
 
 	/*
 	 * First thing is to establish what we expect to find in the log
···
 						       "checksum recovering "
 						       "block %llu in log\n",
 						       blocknr);
-						continue;
+						block_error = 1;
+						goto skip_write;
 					}
 
 					/* Find a buffer for the new
···
 				success = -EIO;
 		}
 	}
-
+	if (block_error && success == 0)
+		success = -EIO;
 	return success;
 
  failed: