ext4: set type of ac_groups_linear_remaining to __u32 to avoid overflow

Now ac_groups_linear_remaining is of type __u16 and s_mb_max_linear_groups
is of type unsigned int, so an overflow occurs when setting a value above
65535 through the mb_max_linear_groups sysfs interface. Therefore, the
type of ac_groups_linear_remaining is set to __u32 to avoid overflow.

Fixes: 196e402a ("ext4: improve cr 0 / cr 1 group scanning")
CC: stable@kernel.org
Signed-off-by: Baokun Li <libaokun1@huawei.com>
Reviewed-by: Zhang Yi <yi.zhang@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20240319113325.3110393-8-libaokun1@huawei.comSigned-off-by: Theodore Ts'o <tytso@mit.edu>

fs/ext4/mballoc.h

@@ -193,8 +193,8 @@ struct ext4_allocation_context {
 	ext4_grpblk_t	ac_orig_goal_len;
 
 	__u32 ac_flags;		/* allocation hints */
+	__u32 ac_groups_linear_remaining;
 	__u16 ac_groups_scanned;
-	__u16 ac_groups_linear_remaining;
 	__u16 ac_found;
 	__u16 ac_cX_found[EXT4_MB_NUM_CRS];
 	__u16 ac_tail;