jbd2: fix block tag checksum verification brokenness

[karo-tx-linux.git] / fs / jbd2 / commit.c

diff --git a/fs/jbd2/commit.c b/fs/jbd2/commit.c
index 0f53946f13c15d5ab53a5f46c595d2ae9eb3f652..e61d7224a729725380a8c055dbb512e57c6b869b 100644 (file)
--- 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