ext4: calculate and verify checksums for inode bitmaps

Compute and verify the checksum of the inode bitmap; the checkum 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, 29 insertions, 5 deletions

diff --git a/fs/ext4/ialloc.c b/fs/ext4/ialloc.c
index 8207dfab2682..fb897ec183c8 100644
--- a/fs/ext4/ialloc.c
+++ b/fs/ext4/ialloc.c
@@ -82,12 +82,17 @@ static unsigned ext4_init_inode_bitmap(struct super_block *sb,
                 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);
                 return 0;
         }
 
         memset(bh->b_data, 0, (EXT4_INODES_PER_GROUP(sb) + 7) / 8);
         ext4_mark_bitmap_end(EXT4_INODES_PER_GROUP(sb), sb->s_blocksize * 8,
                         bh->b_data);
+        ext4_inode_bitmap_csum_set(sb, block_group, gdp, bh,
+                                   EXT4_INODES_PER_GROUP(sb) / 8);
+        gdp->bg_checksum = ext4_group_desc_csum(sbi, block_group, gdp);
 
         return EXT4_INODES_PER_GROUP(sb);
 }
@@ -128,12 +133,12 @@ ext4_read_inode_bitmap(struct super_block *sb, ext4_group_t block_group)
                 return NULL;
         }
         if (bitmap_uptodate(bh))
-                return bh;
+                goto verify;
 
         lock_buffer(bh);
         if (bitmap_uptodate(bh)) {
                 unlock_buffer(bh);
-                return bh;
+                goto verify;
         }
 
         ext4_lock_group(sb, block_group);
@@ -141,6 +146,7 @@ ext4_read_inode_bitmap(struct super_block *sb, ext4_group_t block_group)
                 ext4_init_inode_bitmap(sb, bh, block_group, desc);
                 set_bitmap_uptodate(bh);
                 set_buffer_uptodate(bh);
+                set_buffer_verified(bh);
                 ext4_unlock_group(sb, block_group);
                 unlock_buffer(bh);
                 return bh;
@@ -154,7 +160,7 @@ ext4_read_inode_bitmap(struct super_block *sb, ext4_group_t block_group)
                  */
                 set_bitmap_uptodate(bh);
                 unlock_buffer(bh);
-                return bh;
+                goto verify;
         }
         /*
          * submit the buffer_head for reading
@@ -171,6 +177,20 @@ ext4_read_inode_bitmap(struct super_block *sb, ext4_group_t block_group)
                            block_group, bitmap_blk);
                 return NULL;
         }
+
+verify:
+        ext4_lock_group(sb, block_group);
+        if (!buffer_verified(bh) &&
+            !ext4_inode_bitmap_csum_verify(sb, block_group, desc, bh,
+                                           EXT4_INODES_PER_GROUP(sb) / 8)) {
+                ext4_unlock_group(sb, block_group);
+                put_bh(bh);
+                ext4_error(sb, "Corrupt inode bitmap - block_group = %u, "
+                           "inode_bitmap = %llu", block_group, bitmap_blk);
+                return NULL;
+        }
+        ext4_unlock_group(sb, block_group);
+        set_buffer_verified(bh);
         return bh;
 }
 
@@ -276,6 +296,8 @@ void ext4_free_inode(handle_t *handle, struct inode *inode)
                 ext4_used_dirs_set(sb, gdp, count);
                 percpu_counter_dec(&sbi->s_dirs_counter);
         }
+        ext4_inode_bitmap_csum_set(sb, block_group, gdp, bitmap_bh,
+                                   EXT4_INODES_PER_GROUP(sb) / 8);
         gdp->bg_checksum = ext4_group_desc_csum(sbi, block_group, gdp);
         ext4_unlock_group(sb, block_group);
 
@@ -751,7 +773,7 @@ got:
                 goto fail;
 
         /* Update the relevant bg descriptor fields */
-        if (EXT4_HAS_RO_COMPAT_FEATURE(sb, EXT4_FEATURE_RO_COMPAT_GDT_CSUM)) {
+        if (ext4_has_group_desc_csum(sb)) {
                 int free;
                 struct ext4_group_info *grp = ext4_get_group_info(sb, group);
 
@@ -782,7 +804,9 @@ got:
                         atomic_inc(&sbi->s_flex_groups[f].used_dirs);
                 }
         }
-        if (EXT4_HAS_RO_COMPAT_FEATURE(sb, EXT4_FEATURE_RO_COMPAT_GDT_CSUM)) {
+        if (ext4_has_group_desc_csum(sb)) {
+                ext4_inode_bitmap_csum_set(sb, group, gdp, inode_bitmap_bh,
+                                           EXT4_INODES_PER_GROUP(sb) / 8);
                 gdp->bg_checksum = ext4_group_desc_csum(sbi, group, gdp);
                 ext4_unlock_group(sb, group);
         }