ext4: use ext4_grpblk_t more extensively

unsigned  short is potentially too small to track blocks within
a group; today it is safe due to restrictions in e2fsprogs but
we have _lo / _hi bits for group blocks with the intent to go
up to 32 bits, so clean this up now.

There are many more places where we use unsigned/int/unsigned int
to contain a group block but this should at least fix all the
short types.

I added a few comments to the struct ext4_group_info definition
as well.
Signed-off-by: NEric Sandeen <sandeen@redhat.com>
Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>

fs/ext4/ext4.h

@@ -1577,15 +1577,18 @@ static inline void ext4_update_i_disksize(struct inode *inode, loff_t newsize)
 struct ext4_group_info {
 	unsigned long   bb_state;
 	struct rb_root  bb_free_root;
-	unsigned short  bb_first_free;
-	unsigned short  bb_free;
-	unsigned short  bb_fragments;
+	ext4_grpblk_t	bb_first_free;	/* first free block */
+	ext4_grpblk_t	bb_free;	/* total free blocks */
+	ext4_grpblk_t	bb_fragments;	/* nr of freespace fragments */
 	struct          list_head bb_prealloc_list;
 #ifdef DOUBLE_CHECK
 	void            *bb_bitmap;
 #endif
 	struct rw_semaphore alloc_sem;
-	unsigned short  bb_counters[];
+	ext4_grpblk_t	bb_counters[];	/* Nr of free power-of-two-block
+					 * regions, index is order.
+					 * bb_counters[3] = 5 means
+					 * 5 free 8-block regions. */
 };
 
 #define EXT4_GROUP_INFO_NEED_INIT_BIT	0

fs/ext4/mballoc.c

@@ -623,13 +623,13 @@ static int __mb_check_buddy(struct ext4_buddy *e4b, char *file,
 
 /* FIXME!! need more doc */
 static void ext4_mb_mark_free_simple(struct super_block *sb,
-				void *buddy, unsigned first, int len,
+				void *buddy, ext4_grpblk_t first, ext4_grpblk_t len,
 					struct ext4_group_info *grp)
 {
 	struct ext4_sb_info *sbi = EXT4_SB(sb);
-	unsigned short min;
-	unsigned short max;
-	unsigned short chunk;
+	ext4_grpblk_t min;
+	ext4_grpblk_t max;
+	ext4_grpblk_t chunk;
 	unsigned short border;
 
 	BUG_ON(len > EXT4_BLOCKS_PER_GROUP(sb));
@@ -663,10 +663,10 @@ void ext4_mb_generate_buddy(struct super_block *sb,
 				void *buddy, void *bitmap, ext4_group_t group)
 {
 	struct ext4_group_info *grp = ext4_get_group_info(sb, group);
-	unsigned short max = EXT4_BLOCKS_PER_GROUP(sb);
-	unsigned short i = 0;
-	unsigned short first;
-	unsigned short len;
+	ext4_grpblk_t max = EXT4_BLOCKS_PER_GROUP(sb);
+	ext4_grpblk_t i = 0;
+	ext4_grpblk_t first;
+	ext4_grpblk_t len;
 	unsigned free = 0;
 	unsigned fragments = 0;
 	unsigned long long period = get_cycles();
@@ -2325,7 +2325,7 @@ static int ext4_mb_seq_groups_show(struct seq_file *seq, void *v)
 	struct ext4_buddy e4b;
 	struct sg {
 		struct ext4_group_info info;
-		unsigned short counters[16];
+		ext4_grpblk_t counters[16];
 	} sg;
 
 	group--;

fs/ext4/mballoc.h

@@ -136,8 +136,8 @@ struct ext4_prealloc_space {
 	unsigned		pa_deleted;
 	ext4_fsblk_t		pa_pstart;	/* phys. block */
 	ext4_lblk_t		pa_lstart;	/* log. block */
-	unsigned short		pa_len;		/* len of preallocated chunk */
-	unsigned short		pa_free;	/* how many blocks are free */
+	ext4_grpblk_t		pa_len;		/* len of preallocated chunk */
+	ext4_grpblk_t		pa_free;	/* how many blocks are free */
 	unsigned short		pa_type;	/* pa type. inode or group */
 	spinlock_t		*pa_obj_lock;
 	struct inode		*pa_inode;	/* hack, for history only */
@@ -152,7 +152,7 @@ struct ext4_free_extent {
 	ext4_lblk_t fe_logical;
 	ext4_grpblk_t fe_start;
 	ext4_group_t fe_group;
-	int fe_len;
+	ext4_grpblk_t fe_len;
 };
 
 /*