dm vdo: force read-only mode for a corrupt recovery journal

Ensure the recovery journal does not attempt recovery when blocks
with mismatched metadata versions are detected. This check is
performed after determining that the blocks are otherwise valid
so that it does not interfere with normal recovery.

Signed-off-by: Susan LeGendre-McGhee <[e-mail]>
Signed-off-by: Matthew Sakai <[e-mail]>
Signed-off-by: Mikulas Patocka <[e-mail]>

drivers/md/dm-vdo/repair.c

···
  * @journal: The journal to use.
  * @header: The unpacked block header to check.
  * @sequence: The expected sequence number.
- * @type: The expected metadata type.
  *
  * Return: True if the block matches.
  */
 static bool __must_check is_exact_recovery_journal_block(const struct recovery_journal *journal,
 							 const struct recovery_block_header *header,
-							 sequence_number_t sequence,
-							 enum vdo_metadata_type type)
+							 sequence_number_t sequence)
 {
-	return ((header->metadata_type == type) &&
-		(header->sequence_number == sequence) &&
+	return ((header->sequence_number == sequence) &&
 		(is_valid_recovery_journal_block(journal, header, true)));
 }
 
···
 		get_recovery_journal_block_header(journal, repair->journal_data,
 						  sequence);
 
-	if (!is_exact_recovery_journal_block(journal, &header, sequence, format)) {
+	if (!is_exact_recovery_journal_block(journal, &header, sequence) ||
+	    (header.metadata_type != format)) {
 		/* This block is invalid, so skip it. */
 		return;
 	}
···
 	sequence_number_t i, head;
 	bool found_entries = false;
 	struct recovery_journal *journal = repair->completion.vdo->recovery_journal;
+	struct recovery_block_header header;
+	enum vdo_metadata_type expected_format;
 
 	head = min(repair->block_map_head, repair->slab_journal_head);
+	header = get_recovery_journal_block_header(journal, repair->journal_data, head);
+	expected_format = header.metadata_type;
 	for (i = head; i <= repair->highest_tail; i++) {
-		struct recovery_block_header header;
 		journal_entry_count_t block_entries;
 		u8 j;
 
···
 		};
 
 		header = get_recovery_journal_block_header(journal, repair->journal_data, i);
-		if (header.metadata_type == VDO_METADATA_RECOVERY_JOURNAL) {
-			/* This is an old format block, so we need to upgrade */
-			vdo_log_error_strerror(VDO_UNSUPPORTED_VERSION,
-					       "Recovery journal is in the old format. Downgrade and complete recovery, then upgrade with a clean volume");
-			return VDO_UNSUPPORTED_VERSION;
-		}
-
-		if (!is_exact_recovery_journal_block(journal, &header, i,
-						     VDO_METADATA_RECOVERY_JOURNAL_2)) {
+		if (!is_exact_recovery_journal_block(journal, &header, i)) {
 			/* A bad block header was found so this must be the end of the journal. */
 			break;
+		} else if (header.metadata_type != expected_format) {
+			/* There is a mix of old and new format blocks, so we need to rebuild. */
+			vdo_log_error_strerror(VDO_CORRUPT_JOURNAL,
+					       "Recovery journal is in an invalid format, a read-only rebuild is required.");
+			vdo_enter_read_only_mode(repair->completion.vdo, VDO_CORRUPT_JOURNAL);
+			return VDO_CORRUPT_JOURNAL;
 		}
 
 		block_entries = header.entry_count;
···
 			break;
 	}
 
-	if (!found_entries)
+	if (!found_entries) {
 		return validate_heads(repair);
+	} else if (expected_format == VDO_METADATA_RECOVERY_JOURNAL) {
+		/* All journal blocks have the old format, so we need to upgrade. */
+		vdo_log_error_strerror(VDO_UNSUPPORTED_VERSION,
+				       "Recovery journal is in the old format. Downgrade and complete recovery, then upgrade with a clean volume");
+		return VDO_UNSUPPORTED_VERSION;
+	}
 
 	/* Set the tail to the last valid tail block, if there is one. */
 	if (repair->tail_recovery_point.sector_count == 0)

drivers/md/dm-vdo/status-codes.c

···
 	{ "VDO_LOCK_ERROR", "A lock is held incorrectly" },
 	{ "VDO_READ_ONLY", "The device is in read-only mode" },
 	{ "VDO_SHUTTING_DOWN", "The device is shutting down" },
-	{ "VDO_CORRUPT_JOURNAL", "Recovery journal entries corrupted" },
+	{ "VDO_CORRUPT_JOURNAL", "Recovery journal corrupted" },
 	{ "VDO_TOO_MANY_SLABS", "Exceeds maximum number of slabs supported" },
 	{ "VDO_INVALID_FRAGMENT", "Compressed block fragment is invalid" },
 	{ "VDO_RETRY_AFTER_REBUILD", "Retry operation after rebuilding finishes" },

drivers/md/dm-vdo/status-codes.h

···
 	VDO_READ_ONLY,
 	/* the VDO is shutting down */
 	VDO_SHUTTING_DOWN,
-	/* the recovery journal has corrupt entries */
+	/* the recovery journal has corrupt entries or corrupt metadata */
 	VDO_CORRUPT_JOURNAL,
 	/* exceeds maximum number of slabs supported */
 	VDO_TOO_MANY_SLABS,