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>

2 files changed, 8 insertions, 11 deletions

diff --git a/fs/ext4/balloc.c b/fs/ext4/balloc.c
index d9b66c4a26e8..dc5d572ebd6a 100644
--- a/fs/ext4/balloc.c
+++ b/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);
diff --git a/fs/ext4/ialloc.c b/fs/ext4/ialloc.c
index d5106078595e..137193ff389b 100644
--- a/fs/ext4/ialloc.c
+++ b/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;
         }