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, 7 insertions, 1 deletions

diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index 99ab428bcfa0..95a388fef397 100644
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -788,7 +788,7 @@ static int ext4_mb_init_cache(struct page *page, char *incore)
         int first_block;
         struct super_block *sb;
         struct buffer_head *bhs;
-        struct buffer_head **bh;
+        struct buffer_head **bh = NULL;
         struct inode *inode;
         char *data;
         char *bitmap;
@@ -2797,6 +2797,8 @@ ext4_mb_mark_diskspace_used(struct ext4_allocation_context *ac,
         }
         len = ext4_free_group_clusters(sb, gdp) - ac->ac_b_ex.fe_len;
         ext4_free_group_clusters_set(sb, gdp, len);
+        ext4_block_bitmap_csum_set(sb, ac->ac_b_ex.fe_group, gdp, bitmap_bh,
+                                   EXT4_BLOCKS_PER_GROUP(sb) / 8);
         gdp->bg_checksum = ext4_group_desc_csum(sbi, ac->ac_b_ex.fe_group, gdp);
 
         ext4_unlock_group(sb, ac->ac_b_ex.fe_group);
@@ -4659,6 +4661,8 @@ do_more:
 
         ret = ext4_free_group_clusters(sb, gdp) + count_clusters;
         ext4_free_group_clusters_set(sb, gdp, ret);
+        ext4_block_bitmap_csum_set(sb, block_group, gdp, bitmap_bh,
+                                   EXT4_BLOCKS_PER_GROUP(sb) / 8);
         gdp->bg_checksum = ext4_group_desc_csum(sbi, block_group, gdp);
         ext4_unlock_group(sb, block_group);
         percpu_counter_add(&sbi->s_freeclusters_counter, count_clusters);
@@ -4803,6 +4807,8 @@ int ext4_group_add_blocks(handle_t *handle, struct super_block *sb,
         mb_free_blocks(NULL, &e4b, bit, count);
         blk_free_count = blocks_freed + ext4_free_group_clusters(sb, desc);
         ext4_free_group_clusters_set(sb, desc, blk_free_count);
+        ext4_block_bitmap_csum_set(sb, block_group, desc, bitmap_bh,
+                                   EXT4_BLOCKS_PER_GROUP(sb) / 8);
         desc->bg_checksum = ext4_group_desc_csum(sbi, block_group, desc);
         ext4_unlock_group(sb, block_group);
         percpu_counter_add(&sbi->s_freeclusters_counter,