jbd2: checksum commit blocks

Calculate and verify the checksum of commit blocks.  In checksum v2,
deprecate most of the checksum v1 commit block checksum fields, since
each block has its own checksum.
Signed-off-by: Darrick J. Wong <djwong@us.ibm.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

fs/jbd2/commit.c

@@ -85,6 +85,24 @@ static void release_buffer_page(struct buffer_head *bh)
 	__brelse(bh);
 }
 
+static void jbd2_commit_block_csum_set(journal_t *j,
+				       struct journal_head *descriptor)
+{
+	struct commit_header *h;
+	__u32 csum;
+
+	if (!JBD2_HAS_INCOMPAT_FEATURE(j, JBD2_FEATURE_INCOMPAT_CSUM_V2))
+		return;
+
+	h = (struct commit_header *)(jh2bh(descriptor)->b_data);
+	h->h_chksum_type = 0;
+	h->h_chksum_size = 0;
+	h->h_chksum[0] = 0;
+	csum = jbd2_chksum(j, j->j_csum_seed, jh2bh(descriptor)->b_data,
+			   j->j_blocksize);
+	h->h_chksum[0] = cpu_to_be32(csum);
+}
+
 /*
  * Done it all: now submit the commit record.  We should have
  * cleaned up our previous buffers by now, so if we are in abort
@@ -128,6 +146,7 @@ static int journal_submit_commit_record(journal_t *journal,
 		tmp->h_chksum_size 	= JBD2_CRC32_CHKSUM_SIZE;
 		tmp->h_chksum[0] 	= cpu_to_be32(crc32_sum);
 	}
+	jbd2_commit_block_csum_set(journal, descriptor);
 
 	JBUFFER_TRACE(descriptor, "submit commit block");
 	lock_buffer(bh);

fs/jbd2/recovery.c

@@ -375,6 +375,24 @@ static int calc_chksums(journal_t *journal, struct buffer_head *bh,
 	return 0;
 }
 
+static int jbd2_commit_block_csum_verify(journal_t *j, void *buf)
+{
+	struct commit_header *h;
+	__u32 provided, calculated;
+
+	if (!JBD2_HAS_INCOMPAT_FEATURE(j, JBD2_FEATURE_INCOMPAT_CSUM_V2))
+		return 1;
+
+	h = buf;
+	provided = h->h_chksum[0];
+	h->h_chksum[0] = 0;
+	calculated = jbd2_chksum(j, j->j_csum_seed, buf, j->j_blocksize);
+	h->h_chksum[0] = provided;
+
+	provided = be32_to_cpu(provided);
+	return provided == calculated;
+}
+
 static int do_one_pass(journal_t *journal,
 			struct recovery_info *info, enum passtype pass)
 {
@@ -685,6 +703,19 @@ static int do_one_pass(journal_t *journal,
 				}
 				crc32_sum = ~0;
 			}
+			if (pass == PASS_SCAN &&
+			    !jbd2_commit_block_csum_verify(journal,
+							   bh->b_data)) {
+				info->end_transaction = next_commit_ID;
+
+				if (!JBD2_HAS_INCOMPAT_FEATURE(journal,
+				     JBD2_FEATURE_INCOMPAT_ASYNC_COMMIT)) {
+					journal->j_failed_commit =
+						next_commit_ID;
+					brelse(bh);
+					break;
+				}
+			}
 			brelse(bh);
 			next_commit_ID++;
 			continue;