3 files changed, 24 insertions, 8 deletions

diff --git a/fs/ext4/balloc.c b/fs/ext4/balloc.c
index df77ea891f29..3dacb124b8c8 100644
--- a/fs/ext4/balloc.c
+++ b/fs/ext4/balloc.c
@@ -74,10 +74,12 @@ struct ext4_group_desc * ext4_get_group_desc(struct super_block * sb,
                 return NULL;
         }
 
-        desc = (struct ext4_group_desc *) sbi->s_group_desc[group_desc]->b_data;
+        desc = (struct ext4_group_desc *)(
+                (__u8 *)sbi->s_group_desc[group_desc]->b_data +
+                offset * EXT4_DESC_SIZE(sb));
         if (bh)
                 *bh = sbi->s_group_desc[group_desc];
-        return desc + offset;
+        return desc;
 }
 
 /**
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index c05dc57148bb..d03e7d85a638 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -2432,14 +2432,16 @@ static ext4_fsblk_t ext4_get_inode_block(struct super_block *sb,
                 return 0;
         }
 
-        gdp = (struct ext4_group_desc *)bh->b_data;
+        gdp = (struct ext4_group_desc *)((__u8 *)bh->b_data +
+                desc * EXT4_DESC_SIZE(sb));
         /*
          * Figure out the offset within the block group inode table
          */
         offset = ((ino - 1) % EXT4_INODES_PER_GROUP(sb)) *
                 EXT4_INODE_SIZE(sb);
-        block = ext4_inode_table(gdp + desc) +
-                        (offset >> EXT4_BLOCK_SIZE_BITS(sb));
+        block = ext4_inode_table(gdp) + (offset >> EXT4_BLOCK_SIZE_BITS(sb));
+
+
 
         iloc->block_group = block_group;
         iloc->offset = offset & (EXT4_BLOCK_SIZE(sb) - 1);
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index d844175e60e8..bc8848bff2f1 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -1268,7 +1268,8 @@ static int ext4_check_descriptors (struct super_block * sb)
                         return 0;
                 }
                 first_block += EXT4_BLOCKS_PER_GROUP(sb);
-                gdp++;
+                gdp = (struct ext4_group_desc *)
+                        ((__u8 *)gdp + EXT4_DESC_SIZE(sb));
         }
 
         ext4_free_blocks_count_set(sbi->s_es, ext4_count_free_blocks(sb));
@@ -1619,7 +1620,18 @@ static int ext4_fill_super (struct super_block *sb, void *data, int silent)
                        sbi->s_frag_size, blocksize);
                 goto failed_mount;
         }
-        sbi->s_frags_per_block = 1;
+        sbi->s_desc_size = le16_to_cpu(es->s_desc_size);
+        if (EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_64BIT)) {
+                if (sbi->s_desc_size < EXT4_MIN_DESC_SIZE ||
+                    sbi->s_desc_size > EXT4_MAX_DESC_SIZE ||
+                    sbi->s_desc_size & (sbi->s_desc_size - 1)) {
+                        printk(KERN_ERR
+                               "EXT4-fs: unsupported descriptor size %ld\n",
+                               sbi->s_desc_size);
+                        goto failed_mount;
+                }
+        } else
+                sbi->s_desc_size = EXT4_MIN_DESC_SIZE;
         sbi->s_blocks_per_group = le32_to_cpu(es->s_blocks_per_group);
         sbi->s_frags_per_group = le32_to_cpu(es->s_frags_per_group);
         sbi->s_inodes_per_group = le32_to_cpu(es->s_inodes_per_group);
@@ -1630,7 +1642,7 @@ static int ext4_fill_super (struct super_block *sb, void *data, int silent)
                 goto cantfind_ext4;
         sbi->s_itb_per_group = sbi->s_inodes_per_group /
                                         sbi->s_inodes_per_block;
-        sbi->s_desc_per_block = blocksize / sizeof(struct ext4_group_desc);
+        sbi->s_desc_per_block = blocksize / EXT4_DESC_SIZE(sb);
         sbi->s_sbh = bh;
         sbi->s_mount_state = le16_to_cpu(es->s_state);
         sbi->s_addr_per_block_bits = log2(EXT4_ADDR_PER_BLOCK(sb));