On 2021/05/27 10:02, Bart Van Assche wrote:
> Modern compilers complain if an out-of-range value is passed to a function
> argument that has an enumeration type. Let the compiler detect out-of-range
> data direction arguments instead of verifying the data_dir argument at
> runtime.
>
> Cc: Damien Le Moal <damien.lemoal@xxxxxxx>
> Cc: Christoph Hellwig <hch@xxxxxx>
> Cc: Ming Lei <ming.lei@xxxxxxxxxx>
> Signed-off-by: Bart Van Assche <bvanassche@xxxxxxx>
> ---
> block/mq-deadline.c | 96 +++++++++++++++++++++++----------------------
> 1 file changed, 49 insertions(+), 47 deletions(-)
>
> diff --git a/block/mq-deadline.c b/block/mq-deadline.c
> index c4f51e7884fb..dfbc6b77fa71 100644
> --- a/block/mq-deadline.c
> +++ b/block/mq-deadline.c
> @@ -35,6 +35,13 @@ static const int writes_starved = 2; /* max times reads can starve a write */
> static const int fifo_batch = 16; /* # of sequential requests treated as one
> by the above parameters. For throughput. */
>
> +enum dd_data_dir {
> + DD_READ = READ,
> + DD_WRITE = WRITE,
> +} __packed;
Why the "__packed" here ?
> +
> +enum { DD_DIR_COUNT = 2 };
Why not a simple #define for this one ?
> +
> struct deadline_data {
> /*
> * run time data
> @@ -43,20 +50,20 @@ struct deadline_data {
> /*
> * requests (deadline_rq s) are present on both sort_list and fifo_list
> */
> - struct rb_root sort_list[2];
> - struct list_head fifo_list[2];
> + struct rb_root sort_list[DD_DIR_COUNT];
> + struct list_head fifo_list[DD_DIR_COUNT];
>
> /*
> * next in sort order. read, write or both are NULL
> */
> - struct request *next_rq[2];
> + struct request *next_rq[DD_DIR_COUNT];
> unsigned int batching; /* number of sequential requests made */
> unsigned int starved; /* times reads have starved writes */
>
> /*
> * settings that change how the i/o scheduler behaves
> */
> - int fifo_expire[2];
> + int fifo_expire[DD_DIR_COUNT];
> int fifo_batch;
> int writes_starved;
> int front_merges;
> @@ -97,7 +104,7 @@ deadline_add_rq_rb(struct deadline_data *dd, struct request *rq)
> static inline void
> deadline_del_rq_rb(struct deadline_data *dd, struct request *rq)
> {
> - const int data_dir = rq_data_dir(rq);
> + const enum dd_data_dir data_dir = rq_data_dir(rq);
>
> if (dd->next_rq[data_dir] == rq)
> dd->next_rq[data_dir] = deadline_latter_request(rq);
> @@ -169,10 +176,10 @@ static void dd_merged_requests(struct request_queue *q, struct request *req,
> static void
> deadline_move_request(struct deadline_data *dd, struct request *rq)
> {
> - const int data_dir = rq_data_dir(rq);
> + const enum dd_data_dir data_dir = rq_data_dir(rq);
>
> - dd->next_rq[READ] = NULL;
> - dd->next_rq[WRITE] = NULL;
> + dd->next_rq[DD_READ] = NULL;
> + dd->next_rq[DD_WRITE] = NULL;
> dd->next_rq[data_dir] = deadline_latter_request(rq);
>
> /*
> @@ -185,9 +192,10 @@ deadline_move_request(struct deadline_data *dd, struct request *rq)
> * deadline_check_fifo returns 0 if there are no expired requests on the fifo,
> * 1 otherwise. Requires !list_empty(&dd->fifo_list[data_dir])
> */
> -static inline int deadline_check_fifo(struct deadline_data *dd, int ddir)
> +static inline int deadline_check_fifo(struct deadline_data *dd,
> + enum dd_data_dir data_dir)
> {
> - struct request *rq = rq_entry_fifo(dd->fifo_list[ddir].next);
> + struct request *rq = rq_entry_fifo(dd->fifo_list[data_dir].next);
>
> /*
> * rq is expired!
> @@ -203,19 +211,16 @@ static inline int deadline_check_fifo(struct deadline_data *dd, int ddir)
> * dispatch using arrival ordered lists.
> */
> static struct request *
> -deadline_fifo_request(struct deadline_data *dd, int data_dir)
> +deadline_fifo_request(struct deadline_data *dd, enum dd_data_dir data_dir)
> {
> struct request *rq;
> unsigned long flags;
>
> - if (WARN_ON_ONCE(data_dir != READ && data_dir != WRITE))
> - return NULL;
> -
> if (list_empty(&dd->fifo_list[data_dir]))
> return NULL;
>
> rq = rq_entry_fifo(dd->fifo_list[data_dir].next);
> - if (data_dir == READ || !blk_queue_is_zoned(rq->q))
> + if (data_dir == DD_READ || !blk_queue_is_zoned(rq->q))
> return rq;
>
> /*
> @@ -223,7 +228,7 @@ deadline_fifo_request(struct deadline_data *dd, int data_dir)
> * an unlocked target zone.
> */
> spin_lock_irqsave(&dd->zone_lock, flags);
> - list_for_each_entry(rq, &dd->fifo_list[WRITE], queuelist) {
> + list_for_each_entry(rq, &dd->fifo_list[DD_WRITE], queuelist) {
> if (blk_req_can_dispatch_to_zone(rq))
> goto out;
> }
> @@ -239,19 +244,16 @@ deadline_fifo_request(struct deadline_data *dd, int data_dir)
> * dispatch using sector position sorted lists.
> */
> static struct request *
> -deadline_next_request(struct deadline_data *dd, int data_dir)
> +deadline_next_request(struct deadline_data *dd, enum dd_data_dir data_dir)
> {
> struct request *rq;
> unsigned long flags;
>
> - if (WARN_ON_ONCE(data_dir != READ && data_dir != WRITE))
> - return NULL;
> -
> rq = dd->next_rq[data_dir];
> if (!rq)
> return NULL;
>
> - if (data_dir == READ || !blk_queue_is_zoned(rq->q))
> + if (data_dir == DD_READ || !blk_queue_is_zoned(rq->q))
> return rq;
>
> /*
> @@ -276,7 +278,7 @@ deadline_next_request(struct deadline_data *dd, int data_dir)
> static struct request *__dd_dispatch_request(struct deadline_data *dd)
> {
> struct request *rq, *next_rq;
> - int data_dir;
> + enum dd_data_dir data_dir;
>
> lockdep_assert_held(&dd->lock);
>
> @@ -289,9 +291,9 @@ static struct request *__dd_dispatch_request(struct deadline_data *dd)
> /*
> * batches are currently reads XOR writes
> */
> - rq = deadline_next_request(dd, WRITE);
> + rq = deadline_next_request(dd, DD_WRITE);
> if (!rq)
> - rq = deadline_next_request(dd, READ);
> + rq = deadline_next_request(dd, DD_READ);
>
> if (rq && dd->batching < dd->fifo_batch)
> /* we have a next request are still entitled to batch */
> @@ -302,14 +304,14 @@ static struct request *__dd_dispatch_request(struct deadline_data *dd)
> * data direction (read / write)
> */
>
> - if (!list_empty(&dd->fifo_list[READ])) {
> - BUG_ON(RB_EMPTY_ROOT(&dd->sort_list[READ]));
> + if (!list_empty(&dd->fifo_list[DD_READ])) {
> + BUG_ON(RB_EMPTY_ROOT(&dd->sort_list[DD_READ]));
>
> - if (deadline_fifo_request(dd, WRITE) &&
> + if (deadline_fifo_request(dd, DD_WRITE) &&
> (dd->starved++ >= dd->writes_starved))
> goto dispatch_writes;
>
> - data_dir = READ;
> + data_dir = DD_READ;
>
> goto dispatch_find_request;
> }
> @@ -318,13 +320,13 @@ static struct request *__dd_dispatch_request(struct deadline_data *dd)
> * there are either no reads or writes have been starved
> */
>
> - if (!list_empty(&dd->fifo_list[WRITE])) {
> + if (!list_empty(&dd->fifo_list[DD_WRITE])) {
> dispatch_writes:
> - BUG_ON(RB_EMPTY_ROOT(&dd->sort_list[WRITE]));
> + BUG_ON(RB_EMPTY_ROOT(&dd->sort_list[DD_WRITE]));
>
> dd->starved = 0;
>
> - data_dir = WRITE;
> + data_dir = DD_WRITE;
>
> goto dispatch_find_request;
> }
> @@ -399,8 +401,8 @@ static void dd_exit_sched(struct elevator_queue *e)
> {
> struct deadline_data *dd = e->elevator_data;
>
> - BUG_ON(!list_empty(&dd->fifo_list[READ]));
> - BUG_ON(!list_empty(&dd->fifo_list[WRITE]));
> + BUG_ON(!list_empty(&dd->fifo_list[DD_READ]));
> + BUG_ON(!list_empty(&dd->fifo_list[DD_WRITE]));
>
> kfree(dd);
> }
> @@ -424,12 +426,12 @@ static int dd_init_sched(struct request_queue *q, struct elevator_type *e)
> }
> eq->elevator_data = dd;
>
> - INIT_LIST_HEAD(&dd->fifo_list[READ]);
> - INIT_LIST_HEAD(&dd->fifo_list[WRITE]);
> - dd->sort_list[READ] = RB_ROOT;
> - dd->sort_list[WRITE] = RB_ROOT;
> - dd->fifo_expire[READ] = read_expire;
> - dd->fifo_expire[WRITE] = write_expire;
> + INIT_LIST_HEAD(&dd->fifo_list[DD_READ]);
> + INIT_LIST_HEAD(&dd->fifo_list[DD_WRITE]);
> + dd->sort_list[DD_READ] = RB_ROOT;
> + dd->sort_list[DD_WRITE] = RB_ROOT;
> + dd->fifo_expire[DD_READ] = read_expire;
> + dd->fifo_expire[DD_WRITE] = write_expire;
> dd->writes_starved = writes_starved;
> dd->front_merges = 1;
> dd->fifo_batch = fifo_batch;
> @@ -497,7 +499,7 @@ static void dd_insert_request(struct blk_mq_hw_ctx *hctx, struct request *rq,
> {
> struct request_queue *q = hctx->queue;
> struct deadline_data *dd = q->elevator->elevator_data;
> - const int data_dir = rq_data_dir(rq);
> + const enum dd_data_dir data_dir = rq_data_dir(rq);>
> lockdep_assert_held(&dd->lock);
>
> @@ -585,7 +587,7 @@ static void dd_finish_request(struct request *rq)
>
> spin_lock_irqsave(&dd->zone_lock, flags);
> blk_req_zone_write_unlock(rq);
> - if (!list_empty(&dd->fifo_list[WRITE]))
> + if (!list_empty(&dd->fifo_list[DD_WRITE]))
> blk_mq_sched_mark_restart_hctx(rq->mq_hctx);
> spin_unlock_irqrestore(&dd->zone_lock, flags);
> }
> @@ -626,8 +628,8 @@ static ssize_t __FUNC(struct elevator_queue *e, char *page) \
> __data = jiffies_to_msecs(__data); \
> return deadline_var_show(__data, (page)); \
> }
> -SHOW_FUNCTION(deadline_read_expire_show, dd->fifo_expire[READ], 1);
> -SHOW_FUNCTION(deadline_write_expire_show, dd->fifo_expire[WRITE], 1);
> +SHOW_FUNCTION(deadline_read_expire_show, dd->fifo_expire[DD_READ], 1);
> +SHOW_FUNCTION(deadline_write_expire_show, dd->fifo_expire[DD_WRITE], 1);
> SHOW_FUNCTION(deadline_writes_starved_show, dd->writes_starved, 0);
> SHOW_FUNCTION(deadline_front_merges_show, dd->front_merges, 0);
> SHOW_FUNCTION(deadline_fifo_batch_show, dd->fifo_batch, 0);
> @@ -649,8 +651,8 @@ static ssize_t __FUNC(struct elevator_queue *e, const char *page, size_t count)
> *(__PTR) = __data; \
> return count; \
> }
> -STORE_FUNCTION(deadline_read_expire_store, &dd->fifo_expire[READ], 0, INT_MAX, 1);
> -STORE_FUNCTION(deadline_write_expire_store, &dd->fifo_expire[WRITE], 0, INT_MAX, 1);
> +STORE_FUNCTION(deadline_read_expire_store, &dd->fifo_expire[DD_READ], 0, INT_MAX, 1);
> +STORE_FUNCTION(deadline_write_expire_store, &dd->fifo_expire[DD_WRITE], 0, INT_MAX, 1);
> STORE_FUNCTION(deadline_writes_starved_store, &dd->writes_starved, INT_MIN, INT_MAX, 0);
> STORE_FUNCTION(deadline_front_merges_store, &dd->front_merges, 0, 1, 0);
> STORE_FUNCTION(deadline_fifo_batch_store, &dd->fifo_batch, 0, INT_MAX, 0);
> @@ -717,8 +719,8 @@ static int deadline_##name##_next_rq_show(void *data, \
> __blk_mq_debugfs_rq_show(m, rq); \
> return 0; \
> }
> -DEADLINE_DEBUGFS_DDIR_ATTRS(READ, read)
> -DEADLINE_DEBUGFS_DDIR_ATTRS(WRITE, write)
> +DEADLINE_DEBUGFS_DDIR_ATTRS(DD_READ, read)
> +DEADLINE_DEBUGFS_DDIR_ATTRS(DD_WRITE, write)
> #undef DEADLINE_DEBUGFS_DDIR_ATTRS
>
> static int deadline_batching_show(void *data, struct seq_file *m)
>
--
Damien Le Moal
Western Digital Research
