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Subject[PATCH 22/22] jbd2: Checksum data blocks that are stored in the journal
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Calculate and verify checksums of each data block being stored in the journal.

Signed-off-by: Darrick J. Wong <djwong@us.ibm.com>
---
fs/jbd2/commit.c | 22 ++++++++++++++++++++++
fs/jbd2/journal.c | 10 ++++++++--
fs/jbd2/recovery.c | 30 ++++++++++++++++++++++++++++++
include/linux/jbd2.h | 1 +
4 files changed, 61 insertions(+), 2 deletions(-)

diff --git a/fs/jbd2/commit.c b/fs/jbd2/commit.c
index e083e55..231a02f 100644
--- a/fs/jbd2/commit.c
+++ b/fs/jbd2/commit.c
@@ -339,6 +339,26 @@ 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_uuid_csum, (__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
*
@@ -649,6 +669,8 @@ 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_be32(tag_flag);
+ jbd2_block_tag_csum_set(journal, tag, jh2bh(new_jh),
+ commit_transaction->t_tid);
tagp += tag_bytes;
space_left -= tag_bytes;

diff --git a/fs/jbd2/journal.c b/fs/jbd2/journal.c
index bea3c6e..e7e414f 100644
--- a/fs/jbd2/journal.c
+++ b/fs/jbd2/journal.c
@@ -1989,10 +1989,16 @@ 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;
}

/*
diff --git a/fs/jbd2/recovery.c b/fs/jbd2/recovery.c
index 173e543..d4ad942 100644
--- a/fs/jbd2/recovery.c
+++ b/fs/jbd2/recovery.c
@@ -390,6 +390,23 @@ 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_uuid_csum, (__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)
{
@@ -566,6 +583,19 @@ 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,
diff --git a/include/linux/jbd2.h b/include/linux/jbd2.h
index d948ddf..3ca096f 100644
--- a/include/linux/jbd2.h
+++ b/include/linux/jbd2.h
@@ -190,6 +190,7 @@ typedef struct journal_block_tag_s
__be32 t_blocknr; /* The on-disk block number */
__be32 t_flags; /* See below */
__be32 t_blocknr_high; /* most-significant high 32bits. */
+ __be32 t_checksum; /* crc32c(uuid+seq+block) */
} journal_block_tag_t;

#define JBD2_TAG_SIZE32 (offsetof(journal_block_tag_t, t_blocknr_high))


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