ext4: calculate and verify block bitmap checksum

Compute and verify the checksum of the block bitmap; this checksum is
stored in the block group descriptor.

Signed-off-by: Darrick J. Wong <djwong@us.ibm.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

1 files changed, 4 insertions, 0 deletions

diff --git a/fs/ext4/ialloc.c b/fs/ext4/ialloc.c
index fb897ec183c8..a6383fcb714b 100644
--- a/fs/ext4/ialloc.c
+++ b/fs/ext4/ialloc.c
@@ -753,6 +753,10 @@ got:
                         gdp->bg_flags &= cpu_to_le16(~EXT4_BG_BLOCK_UNINIT);
                         ext4_free_group_clusters_set(sb, gdp,
                                 ext4_free_clusters_after_init(sb, group, gdp));
+                        ext4_block_bitmap_csum_set(sb, group, gdp,
+                                                   block_bitmap_bh,
+                                                   EXT4_BLOCKS_PER_GROUP(sb) /
+                                                   8);
                         gdp->bg_checksum = ext4_group_desc_csum(sbi, group,
                                                                 gdp);
                 }