jbd2: checksum data blocks that are stored in the journal

Calculate and verify checksums of each data block being stored in the journal.
Signed-off-by: Darrick J. Wong <djwong@us.ibm.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

fs/jbd2/commit.c

@@ -338,6 +338,26 @@ static void jbd2_descr_block_csum_set(journal_t *j,
 	tail->t_checksum = cpu_to_be32(csum);
 }
 
+static void jbd2_block_tag_csum_set(journal_t *j, journal_block_tag_t *tag,
+				    struct buffer_head *bh, __u32 sequence)
+{
+	struct page *page = bh->b_page;
+	__u8 *addr;
+	__u32 csum;
+
+	if (!JBD2_HAS_INCOMPAT_FEATURE(j, JBD2_FEATURE_INCOMPAT_CSUM_V2))
+		return;
+
+	sequence = cpu_to_be32(sequence);
+	addr = kmap_atomic(page, KM_USER0);
+	csum = jbd2_chksum(j, j->j_csum_seed, (__u8 *)&sequence,
+			  sizeof(sequence));
+	csum = jbd2_chksum(j, csum, addr + offset_in_page(bh->b_data),
+			  bh->b_size);
+	kunmap_atomic(addr, KM_USER0);
+
+	tag->t_checksum = cpu_to_be32(csum);
+}
 /*
  * jbd2_journal_commit_transaction
  *
@@ -669,6 +689,8 @@ void jbd2_journal_commit_transaction(journal_t *journal)
 		tag = (journal_block_tag_t *) tagp;
 		write_tag_block(tag_bytes, tag, jh2bh(jh)->b_blocknr);
 		tag->t_flags = cpu_to_be16(tag_flag);
+		jbd2_block_tag_csum_set(journal, tag, jh2bh(new_jh),
+					commit_transaction->t_tid);
 		tagp += tag_bytes;
 		space_left -= tag_bytes;
 

fs/jbd2/journal.c

@@ -2097,10 +2097,16 @@ int jbd2_journal_blocks_per_page(struct inode *inode)
  */
 size_t journal_tag_bytes(journal_t *journal)
 {
+	journal_block_tag_t tag;
+	size_t x = 0;
+
+	if (JBD2_HAS_INCOMPAT_FEATURE(journal, JBD2_FEATURE_INCOMPAT_CSUM_V2))
+		x += sizeof(tag.t_checksum);
+
 	if (JBD2_HAS_INCOMPAT_FEATURE(journal, JBD2_FEATURE_INCOMPAT_64BIT))
-		return JBD2_TAG_SIZE64;
+		return x + JBD2_TAG_SIZE64;
 	else
-		return JBD2_TAG_SIZE32;
+		return x + JBD2_TAG_SIZE32;
 }
 
 /*

fs/jbd2/recovery.c

@@ -393,6 +393,23 @@ static int jbd2_commit_block_csum_verify(journal_t *j, void *buf)
 	return provided == calculated;
 }
 
+static int jbd2_block_tag_csum_verify(journal_t *j, journal_block_tag_t *tag,
+				      void *buf, __u32 sequence)
+{
+	__u32 provided, calculated;
+
+	if (!JBD2_HAS_INCOMPAT_FEATURE(j, JBD2_FEATURE_INCOMPAT_CSUM_V2))
+		return 1;
+
+	sequence = cpu_to_be32(sequence);
+	calculated = jbd2_chksum(j, j->j_csum_seed, (__u8 *)&sequence,
+				 sizeof(sequence));
+	calculated = jbd2_chksum(j, calculated, buf, j->j_blocksize);
+	provided = be32_to_cpu(tag->t_checksum);
+
+	return provided == cpu_to_be32(calculated);
+}
+
 static int do_one_pass(journal_t *journal,
 			struct recovery_info *info, enum passtype pass)
 {
@@ -569,6 +586,19 @@ static int do_one_pass(journal_t *journal,
 						goto skip_write;
 					}
 
+					/* Look for block corruption */
+					if (!jbd2_block_tag_csum_verify(
+						journal, tag, obh->b_data,
+						be32_to_cpu(tmp->h_sequence))) {
+						brelse(obh);
+						success = -EIO;
+						printk(KERN_ERR "JBD: Invalid "
+						       "checksum recovering "
+						       "block %llu in log\n",
+						       blocknr);
+						continue;
+					}
+
 					/* Find a buffer for the new
 					 * data being restored */
 					nbh = __getblk(journal->j_fs_dev,