io-wq: use IO_WQ_ACCT_NR rather than hardcoded number

It's better to use the defined enum stuff not the hardcoded number to
define array.

Signed-off-by: Hao Xu <haoxu@linux.alibaba.com>
Link: https://lore.kernel.org/r/20220206095241.121485-4-haoxu@linux.alibaba.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

fs/io-wq.c

@@ -92,7 +92,7 @@ enum {
  */
 struct io_wqe {
 	raw_spinlock_t lock;
-	struct io_wqe_acct acct[2];
+	struct io_wqe_acct acct[IO_WQ_ACCT_NR];
 
 	int node;
 
@@ -1376,7 +1376,7 @@ int io_wq_max_workers(struct io_wq *wq, int *new_count)
 	BUILD_BUG_ON((int) IO_WQ_ACCT_UNBOUND != (int) IO_WQ_UNBOUND);
 	BUILD_BUG_ON((int) IO_WQ_ACCT_NR      != 2);
 
-	for (i = 0; i < 2; i++) {
+	for (i = 0; i < IO_WQ_ACCT_NR; i++) {
 		if (new_count[i] > task_rlimit(current, RLIMIT_NPROC))
 			new_count[i] = task_rlimit(current, RLIMIT_NPROC);
 	}