ext4: add ext4_group_t, and change all group variables to this type.

In many places variables for block group are of type int, which limits the
maximum number of block groups to 2^31.  Each block group can have up to
2^15 blocks, with a 4K block size,  and the max filesystem size is limited to
2^31 * (2^15 * 2^12) = 2^58  -- or 256 PB

This patch introduces a new type ext4_group_t, of type unsigned long, to
represent block group numbers in ext4.
All occurrences of block group variables are converted to type ext4_group_t.

Signed-off-by: Avantika Mathur <mathur@us.ibm.com>

1 files changed, 4 insertions, 1 deletions

diff --git a/include/linux/ext4_fs_i.h b/include/linux/ext4_fs_i.h
index 6c610b67b047..2b4e3700c725 100644
--- a/include/linux/ext4_fs_i.h
+++ b/include/linux/ext4_fs_i.h
@@ -30,6 +30,9 @@ typedef unsigned long long ext4_fsblk_t;
 /* data type for file logical block number */
 typedef __u32 ext4_lblk_t;
 
+/* data type for block group number */
+typedef unsigned long ext4_group_t;
+
 struct ext4_reserve_window {
         ext4_fsblk_t    _rsv_start;     /* First byte reserved */
         ext4_fsblk_t    _rsv_end;       /* Last byte reserved or 0 */
@@ -92,7 +95,7 @@ struct ext4_inode_info {
          * place a file's data blocks near its inode block, and new inodes
          * near to their parent directory's inode.
          */
-        __u32   i_block_group;
+        ext4_group_t    i_block_group;
         __u32   i_state;                /* Dynamic state flags for ext4 */
 
         /* block reservation info */