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>

3 files changed, 11 insertions, 7 deletions

diff --git a/include/linux/ext4_fs.h b/include/linux/ext4_fs.h
index 5e2da0974d1..e1103c2a0d4 100644
--- a/include/linux/ext4_fs.h
+++ b/include/linux/ext4_fs.h
@@ -830,7 +830,7 @@ struct ext4_iloc
 {
 	struct buffer_head *bh;
 	unsigned long offset;
-	unsigned long block_group;
+	ext4_group_t block_group;
 };
 
 static inline struct ext4_inode *ext4_raw_inode(struct ext4_iloc *iloc)
@@ -855,7 +855,7 @@ struct dir_private_info {
 
 /* calculate the first block number of the group */
 static inline ext4_fsblk_t
-ext4_group_first_block_no(struct super_block *sb, unsigned long group_no)
+ext4_group_first_block_no(struct super_block *sb, ext4_group_t group_no)
 {
 	return group_no * (ext4_fsblk_t)EXT4_BLOCKS_PER_GROUP(sb) +
 		le32_to_cpu(EXT4_SB(sb)->s_es->s_first_data_block);
@@ -886,8 +886,9 @@ extern unsigned int ext4_block_group(struct super_block *sb,
 			ext4_fsblk_t blocknr);
 extern ext4_grpblk_t ext4_block_group_offset(struct super_block *sb,
 			ext4_fsblk_t blocknr);
-extern int ext4_bg_has_super(struct super_block *sb, int group);
-extern unsigned long ext4_bg_num_gdb(struct super_block *sb, int group);
+extern int ext4_bg_has_super(struct super_block *sb, ext4_group_t group);
+extern unsigned long ext4_bg_num_gdb(struct super_block *sb,
+			ext4_group_t group);
 extern ext4_fsblk_t ext4_new_block (handle_t *handle, struct inode *inode,
 			ext4_fsblk_t goal, int *errp);
 extern ext4_fsblk_t ext4_new_blocks (handle_t *handle, struct inode *inode,
@@ -900,7 +901,7 @@ extern void ext4_free_blocks_sb (handle_t *handle, struct super_block *sb,
 extern ext4_fsblk_t ext4_count_free_blocks (struct super_block *);
 extern void ext4_check_blocks_bitmap (struct super_block *);
 extern struct ext4_group_desc * ext4_get_group_desc(struct super_block * sb,
-						    unsigned int block_group,
+						    ext4_group_t block_group,
 						    struct buffer_head ** bh);
 extern int ext4_should_retry_alloc(struct super_block *sb, int *retries);
 extern void ext4_init_block_alloc_info(struct inode *);
diff --git a/include/linux/ext4_fs_i.h b/include/linux/ext4_fs_i.h
index 6c610b67b04..2b4e3700c72 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 */
diff --git a/include/linux/ext4_fs_sb.h b/include/linux/ext4_fs_sb.h
index b40e827cd49..f15821c5e4c 100644
--- a/include/linux/ext4_fs_sb.h
+++ b/include/linux/ext4_fs_sb.h
@@ -35,7 +35,7 @@ struct ext4_sb_info {
 	unsigned long s_itb_per_group;	/* Number of inode table blocks per group */
 	unsigned long s_gdb_count;	/* Number of group descriptor blocks */
 	unsigned long s_desc_per_block;	/* Number of group descriptors per block */
-	unsigned long s_groups_count;	/* Number of groups in the fs */
+	ext4_group_t s_groups_count;	/* Number of groups in the fs */
 	unsigned long s_overhead_last;  /* Last calculated overhead */
 	unsigned long s_blocks_last;    /* Last seen block count */
 	struct buffer_head * s_sbh;	/* Buffer containing the super block */