ext4: mark group corrupt on group descriptor checksum

If the group descriptor fails validation, mark the whole blockgroup
corrupt so that the inode/block allocators skip this group.  The
previous approach takes the risk of writing to a damaged group
descriptor; hopefully it was never the case that the [ib]bitmap fields
pointed to another valid block and got dirtied, since the memset would
fill the page with 1s.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

fs/ext4/balloc.c

@@ -184,6 +184,7 @@ void ext4_init_block_bitmap(struct super_block *sb, struct buffer_head *bh,
 	struct ext4_sb_info *sbi = EXT4_SB(sb);
 	ext4_fsblk_t start, tmp;
 	int flex_bg = 0;
+	struct ext4_group_info *grp;
 
 	J_ASSERT_BH(bh, buffer_locked(bh));
 
@@ -191,11 +192,9 @@ void ext4_init_block_bitmap(struct super_block *sb, struct buffer_head *bh,
 	 * essentially implementing a per-group read-only flag. */
 	if (!ext4_group_desc_csum_verify(sb, block_group, gdp)) {
 		ext4_error(sb, "Checksum bad for group %u", block_group);
-		ext4_free_group_clusters_set(sb, gdp, 0);
-		ext4_free_inodes_set(sb, gdp, 0);
-		ext4_itable_unused_set(sb, gdp, 0);
-		memset(bh->b_data, 0xff, sb->s_blocksize);
-		ext4_block_bitmap_csum_set(sb, block_group, gdp, bh);
+		grp = ext4_get_group_info(sb, block_group);
+		set_bit(EXT4_GROUP_INFO_BBITMAP_CORRUPT_BIT, &grp->bb_state);
+		set_bit(EXT4_GROUP_INFO_IBITMAP_CORRUPT_BIT, &grp->bb_state);
 		return;
 	}
 	memset(bh->b_data, 0, sb->s_blocksize);

fs/ext4/ialloc.c

@@ -70,18 +70,16 @@ static unsigned ext4_init_inode_bitmap(struct super_block *sb,
 				       ext4_group_t block_group,
 				       struct ext4_group_desc *gdp)
 {
+	struct ext4_group_info *grp;
 	J_ASSERT_BH(bh, buffer_locked(bh));
 
 	/* If checksum is bad mark all blocks and inodes use to prevent
 	 * allocation, essentially implementing a per-group read-only flag. */
 	if (!ext4_group_desc_csum_verify(sb, block_group, gdp)) {
 		ext4_error(sb, "Checksum bad for group %u", block_group);
-		ext4_free_group_clusters_set(sb, gdp, 0);
-		ext4_free_inodes_set(sb, gdp, 0);
-		ext4_itable_unused_set(sb, gdp, 0);
-		memset(bh->b_data, 0xff, sb->s_blocksize);
-		ext4_inode_bitmap_csum_set(sb, block_group, gdp, bh,
-					   EXT4_INODES_PER_GROUP(sb) / 8);
+		grp = ext4_get_group_info(sb, block_group);
+		set_bit(EXT4_GROUP_INFO_BBITMAP_CORRUPT_BIT, &grp->bb_state);
+		set_bit(EXT4_GROUP_INFO_IBITMAP_CORRUPT_BIT, &grp->bb_state);
 		return 0;
 	}