Al Viro complained of a ton of bogosity with regards to the jbd2 block tag
header checksum. This one checksum is 16 bits, so cut off the upper 16 bits
and treat it as a 16-bit value and don't mess around with be32* conversions.
Fortunately metadata checksumming is still "experimental" and not in a shipping
e2fsprogs, so there should be few users affected by this.
v2: Eliminate unnecessary variables and make it clear(er) which values are 32
bits wide.
v3: Add a comment about why we're only storing half of the crc32c.
Reported-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
---
fs/jbd2/commit.c | 13 +++++++------
fs/jbd2/recovery.c | 11 +++++------
2 files changed, 12 insertions(+), 12 deletions(-)
diff --git a/fs/jbd2/commit.c b/fs/jbd2/commit.c
index 0f53946..e61d722 100644
--- a/fs/jbd2/commit.c
+++ b/fs/jbd2/commit.c
@@ -343,20 +343,21 @@ static void jbd2_block_tag_csum_set(journal_t *j, journal_block_tag_t *tag,
{
struct page *page = bh->b_page;
__u8 *addr;
- __u32 csum;
+ __u32 csum32;
if (!JBD2_HAS_INCOMPAT_FEATURE(j, JBD2_FEATURE_INCOMPAT_CSUM_V2))
return;
sequence = cpu_to_be32(sequence);
addr = kmap_atomic(page);
- 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);
+ csum32 = jbd2_chksum(j, j->j_csum_seed, (__u8 *)&sequence,
+ sizeof(sequence));
+ csum32 = jbd2_chksum(j, csum32, addr + offset_in_page(bh->b_data),
+ bh->b_size);
kunmap_atomic(addr);
- tag->t_checksum = cpu_to_be32(csum);
+ /* We only have space to store the lower 16 bits of the crc32c. */
+ tag->t_checksum = cpu_to_be16(csum32);
}
/*
* jbd2_journal_commit_transaction
diff --git a/fs/jbd2/recovery.c b/fs/jbd2/recovery.c
index 626846b..d4851464 100644
--- a/fs/jbd2/recovery.c
+++ b/fs/jbd2/recovery.c
@@ -399,18 +399,17 @@ static int jbd2_commit_block_csum_verify(journal_t *j, void *buf)
static int jbd2_block_tag_csum_verify(journal_t *j, journal_block_tag_t *tag,
void *buf, __u32 sequence)
{
- __u32 provided, calculated;
+ __u32 csum32;
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);
+ csum32 = jbd2_chksum(j, j->j_csum_seed, (__u8 *)&sequence,
+ sizeof(sequence));
+ csum32 = jbd2_chksum(j, csum32, buf, j->j_blocksize);
- return provided == cpu_to_be32(calculated);
+ return tag->t_checksum == cpu_to_be16(csum32);
}
static int do_one_pass(journal_t *journal,
--
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