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Commit c5869807 authored by Tejun Heo's avatar Tejun Heo Committed by Jens Axboe
Browse files

block, cfq: reorganize cfq_io_context into generic and cfq specific parts 



Currently io_context and cfq logics are mixed without clear boundary.
Most of io_context is independent from cfq but cfq_io_context handling
logic is dispersed between generic ioc code and cfq.

cfq_io_context represents association between an io_context and a
request_queue, which is a concept useful outside of cfq, but it also
contains fields which are useful only to cfq.

This patch takes out generic part and put it into io_cq (io
context-queue) and the rest into cfq_io_cq (cic moniker remains the
same) which contains io_cq.  The following changes are made together.

* cfq_ttime and cfq_io_cq now live in cfq-iosched.c.

* All related fields, functions and constants are renamed accordingly.

* ioc->ioc_data is now "struct io_cq *" instead of "void *" and
  renamed to icq_hint.

This prepares for io_context API cleanup.  Documentation is currently
sparse.  It will be added later.

Changes in this patch are mechanical and don't cause functional
change.

Signed-off-by: default avatarTejun Heo <tj@kernel.org>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 22f746e2

block/blk-ioc.c

+28 −30
Original line number Diff line number Diff line
@@ -46,7 +46,7 @@ EXPORT_SYMBOL(get_io_context); 


/*

 * Slow path for ioc release in put_io_context().  Performs double-lock

 * dancing to unlink all cic's and then frees ioc.

 * dancing to unlink all icq's and then frees ioc.

 */

static void ioc_release_fn(struct work_struct *work)

{
@@ -56,11 +56,10 @@ static void ioc_release_fn(struct work_struct *work) 


	spin_lock_irq(&ioc->lock);



	while (!hlist_empty(&ioc->cic_list)) {

		struct cfq_io_context *cic = hlist_entry(ioc->cic_list.first,

							 struct cfq_io_context,

							 cic_list);

		struct request_queue *this_q = cic->q;

	while (!hlist_empty(&ioc->icq_list)) {

		struct io_cq *icq = hlist_entry(ioc->icq_list.first,

						struct io_cq, ioc_node);

		struct request_queue *this_q = icq->q;



		if (this_q != last_q) {

			/*
@@ -89,8 +88,8 @@ static void ioc_release_fn(struct work_struct *work) 
			continue;

		}

		ioc_release_depth_inc(this_q);

		cic->exit(cic);

		cic->release(cic);

		icq->exit(icq);

		icq->release(icq);

		ioc_release_depth_dec(this_q);

	}
@@ -131,10 +130,10 @@ void put_io_context(struct io_context *ioc, struct request_queue *locked_q) 
		return;



	/*

	 * Destroy @ioc.  This is a bit messy because cic's are chained

	 * Destroy @ioc.  This is a bit messy because icq's are chained

	 * from both ioc and queue, and ioc->lock nests inside queue_lock.

	 * The inner ioc->lock should be held to walk our cic_list and then

	 * for each cic the outer matching queue_lock should be grabbed.

	 * The inner ioc->lock should be held to walk our icq_list and then

	 * for each icq the outer matching queue_lock should be grabbed.

	 * ie. We need to do reverse-order double lock dancing.

	 *

	 * Another twist is that we are often called with one of the
@@ -153,11 +152,10 @@ void put_io_context(struct io_context *ioc, struct request_queue *locked_q) 
	spin_lock_irqsave_nested(&ioc->lock, flags,

				 ioc_release_depth(locked_q));



	while (!hlist_empty(&ioc->cic_list)) {

		struct cfq_io_context *cic = hlist_entry(ioc->cic_list.first,

							 struct cfq_io_context,

							 cic_list);

		struct request_queue *this_q = cic->q;

	while (!hlist_empty(&ioc->icq_list)) {

		struct io_cq *icq = hlist_entry(ioc->icq_list.first,

						struct io_cq, ioc_node);

		struct request_queue *this_q = icq->q;



		if (this_q != last_q) {

			if (last_q && last_q != locked_q)
@@ -170,8 +168,8 @@ void put_io_context(struct io_context *ioc, struct request_queue *locked_q) 
			continue;

		}

		ioc_release_depth_inc(this_q);

		cic->exit(cic);

		cic->release(cic);

		icq->exit(icq);

		icq->release(icq);

		ioc_release_depth_dec(this_q);

	}
@@ -180,8 +178,8 @@ void put_io_context(struct io_context *ioc, struct request_queue *locked_q) 


	spin_unlock_irqrestore(&ioc->lock, flags);



	/* if no cic's left, we're done; otherwise, kick release_work */

	if (hlist_empty(&ioc->cic_list))

	/* if no icq is left, we're done; otherwise, kick release_work */

	if (hlist_empty(&ioc->icq_list))

		kmem_cache_free(iocontext_cachep, ioc);

	else

		schedule_work(&ioc->release_work);
@@ -219,8 +217,8 @@ void create_io_context_slowpath(struct task_struct *task, gfp_t gfp_flags, 
	atomic_long_set(&ioc->refcount, 1);

	atomic_set(&ioc->nr_tasks, 1);

	spin_lock_init(&ioc->lock);

	INIT_RADIX_TREE(&ioc->radix_root, GFP_ATOMIC | __GFP_HIGH);

	INIT_HLIST_HEAD(&ioc->cic_list);

	INIT_RADIX_TREE(&ioc->icq_tree, GFP_ATOMIC | __GFP_HIGH);

	INIT_HLIST_HEAD(&ioc->icq_list);

	INIT_WORK(&ioc->release_work, ioc_release_fn);



	/* try to install, somebody might already have beaten us to it */
@@ -270,11 +268,11 @@ EXPORT_SYMBOL(get_task_io_context); 


void ioc_set_changed(struct io_context *ioc, int which)

{

	struct cfq_io_context *cic;

	struct io_cq *icq;

	struct hlist_node *n;



	hlist_for_each_entry(cic, n, &ioc->cic_list, cic_list)

		set_bit(which, &cic->changed);

	hlist_for_each_entry(icq, n, &ioc->icq_list, ioc_node)

		set_bit(which, &icq->changed);

}



/**
@@ -282,8 +280,8 @@ void ioc_set_changed(struct io_context *ioc, int which) 
 * @ioc: io_context of interest

 * @ioprio: new ioprio

 *

 * @ioc's ioprio has changed to @ioprio.  Set %CIC_IOPRIO_CHANGED for all

 * cic's.  iosched is responsible for checking the bit and applying it on

 * @ioc's ioprio has changed to @ioprio.  Set %ICQ_IOPRIO_CHANGED for all

 * icq's.  iosched is responsible for checking the bit and applying it on

 * request issue path.

 */

void ioc_ioprio_changed(struct io_context *ioc, int ioprio)
@@ -292,7 +290,7 @@ void ioc_ioprio_changed(struct io_context *ioc, int ioprio) 


	spin_lock_irqsave(&ioc->lock, flags);

	ioc->ioprio = ioprio;

	ioc_set_changed(ioc, CIC_IOPRIO_CHANGED);

	ioc_set_changed(ioc, ICQ_IOPRIO_CHANGED);

	spin_unlock_irqrestore(&ioc->lock, flags);

}
@@ -300,7 +298,7 @@ void ioc_ioprio_changed(struct io_context *ioc, int ioprio) 
 * ioc_cgroup_changed - notify cgroup change

 * @ioc: io_context of interest

 *

 * @ioc's cgroup has changed.  Set %CIC_CGROUP_CHANGED for all cic's.

 * @ioc's cgroup has changed.  Set %ICQ_CGROUP_CHANGED for all icq's.

 * iosched is responsible for checking the bit and applying it on request

 * issue path.

 */
@@ -309,7 +307,7 @@ void ioc_cgroup_changed(struct io_context *ioc) 
	unsigned long flags;



	spin_lock_irqsave(&ioc->lock, flags);

	ioc_set_changed(ioc, CIC_CGROUP_CHANGED);

	ioc_set_changed(ioc, ICQ_CGROUP_CHANGED);

	spin_unlock_irqrestore(&ioc->lock, flags);

}

block/cfq-iosched.c

+133 −115

File changed.

Preview size limit exceeded, changes collapsed.

include/linux/iocontext.h

+14 −29
Original line number Diff line number Diff line
@@ -5,38 +5,23 @@ 
#include <linux/rcupdate.h>

#include <linux/workqueue.h>



struct cfq_queue;

struct cfq_ttime {

	unsigned long last_end_request;



	unsigned long ttime_total;

	unsigned long ttime_samples;

	unsigned long ttime_mean;

};



enum {

	CIC_IOPRIO_CHANGED,

	CIC_CGROUP_CHANGED,

	ICQ_IOPRIO_CHANGED,

	ICQ_CGROUP_CHANGED,

};



struct cfq_io_context {

struct io_cq {

	struct request_queue	*q;



	struct cfq_queue *cfqq[2];



	struct io_context	*ioc;



	struct cfq_ttime ttime;



	struct list_head queue_list;

	struct hlist_node cic_list;

	struct list_head	q_node;

	struct hlist_node	ioc_node;



	unsigned long		changed;



	void (*exit)(struct cfq_io_context *);

	void (*release)(struct cfq_io_context *);



	struct rcu_head		rcu_head;



	void (*exit)(struct io_cq *);

	void (*release)(struct io_cq *);

};



/*
@@ -58,9 +43,9 @@ struct io_context { 
	int nr_batch_requests;     /* Number of requests left in the batch */

	unsigned long last_waited; /* Time last woken after wait for request */



	struct radix_tree_root radix_root;

	struct hlist_head cic_list;

	void __rcu *ioc_data;

	struct radix_tree_root	icq_tree;

	struct io_cq __rcu	*icq_hint;

	struct hlist_head	icq_list;



	struct work_struct release_work;

};