Commit 004a26b3 authored by Bart Van Assche's avatar Bart Van Assche Committed by Jens Axboe
Browse files

block/mq-deadline: Improve compile-time argument checking 



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.

Reviewed-by: default avatarChaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
Reviewed-by: default avatarHannes Reinecke <hare@suse.de>
Reviewed-by: default avatarJohannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: default avatarHimanshu Madhani <himanshu.madhani@oracle.com>
Cc: Damien Le Moal <damien.lemoal@wdc.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Ming Lei <ming.lei@redhat.com>
Signed-off-by: default avatarBart Van Assche <bvanassche@acm.org>
Link: https://lore.kernel.org/r/20210618004456.7280-10-bvanassche@acm.org


Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 3e9a99eb

block/mq-deadline.c

+49 −47
Original line number Diff line number Diff line
@@ -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,

};



enum { DD_DIR_COUNT = 2 };



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)