ioprio: move io priority from task_struct to io_context

This is where it belongs and then it doesn't take up space for a
process that doesn't do IO.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

2 files changed, 37 insertions, 27 deletions

diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index 13553e015d72..533af75329e6 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -199,7 +199,7 @@ CFQ_CFQQ_FNS(sync);
 
 static void cfq_dispatch_insert(struct request_queue *, struct request *);
 static struct cfq_queue *cfq_get_queue(struct cfq_data *, int,
-                                       struct task_struct *, gfp_t);
+                                       struct io_context *, gfp_t);
 static struct cfq_io_context *cfq_cic_rb_lookup(struct cfq_data *,
                                                 struct io_context *);
 
@@ -1273,7 +1273,7 @@ cfq_alloc_io_context(struct cfq_data *cfqd, gfp_t gfp_mask)
         return cic;
 }
 
-static void cfq_init_prio_data(struct cfq_queue *cfqq)
+static void cfq_init_prio_data(struct cfq_queue *cfqq, struct io_context *ioc)
 {
         struct task_struct *tsk = current;
         int ioprio_class;
@@ -1281,7 +1281,7 @@ static void cfq_init_prio_data(struct cfq_queue *cfqq)
         if (!cfq_cfqq_prio_changed(cfqq))
                 return;
 
-        ioprio_class = IOPRIO_PRIO_CLASS(tsk->ioprio);
+        ioprio_class = IOPRIO_PRIO_CLASS(ioc->ioprio);
         switch (ioprio_class) {
                 default:
                         printk(KERN_ERR "cfq: bad prio %x\n", ioprio_class);
@@ -1293,11 +1293,11 @@ static void cfq_init_prio_data(struct cfq_queue *cfqq)
                         cfqq->ioprio_class = IOPRIO_CLASS_BE;
                         break;
                 case IOPRIO_CLASS_RT:
-                        cfqq->ioprio = task_ioprio(tsk);
+                        cfqq->ioprio = task_ioprio(ioc);
                         cfqq->ioprio_class = IOPRIO_CLASS_RT;
                         break;
                 case IOPRIO_CLASS_BE:
-                        cfqq->ioprio = task_ioprio(tsk);
+                        cfqq->ioprio = task_ioprio(ioc);
                         cfqq->ioprio_class = IOPRIO_CLASS_BE;
                         break;
                 case IOPRIO_CLASS_IDLE:
@@ -1330,8 +1330,7 @@ static inline void changed_ioprio(struct cfq_io_context *cic)
         cfqq = cic->cfqq[ASYNC];
         if (cfqq) {
                 struct cfq_queue *new_cfqq;
-                new_cfqq = cfq_get_queue(cfqd, ASYNC, cic->ioc->task,
-                                         GFP_ATOMIC);
+                new_cfqq = cfq_get_queue(cfqd, ASYNC, cic->ioc, GFP_ATOMIC);
                 if (new_cfqq) {
                         cic->cfqq[ASYNC] = new_cfqq;
                         cfq_put_queue(cfqq);
@@ -1363,13 +1362,13 @@ static void cfq_ioc_set_ioprio(struct io_context *ioc)
 
 static struct cfq_queue *
 cfq_find_alloc_queue(struct cfq_data *cfqd, int is_sync,
-                     struct task_struct *tsk, gfp_t gfp_mask)
+                     struct io_context *ioc, gfp_t gfp_mask)
 {
         struct cfq_queue *cfqq, *new_cfqq = NULL;
         struct cfq_io_context *cic;
 
 retry:
-        cic = cfq_cic_rb_lookup(cfqd, tsk->io_context);
+        cic = cfq_cic_rb_lookup(cfqd, ioc);
         /* cic always exists here */
         cfqq = cic_to_cfqq(cic, is_sync);
 
@@ -1412,7 +1411,7 @@ retry:
                 cfq_mark_cfqq_prio_changed(cfqq);
                 cfq_mark_cfqq_queue_new(cfqq);
 
-                cfq_init_prio_data(cfqq);
+                cfq_init_prio_data(cfqq, ioc);
         }
 
         if (new_cfqq)
@@ -1439,11 +1438,11 @@ cfq_async_queue_prio(struct cfq_data *cfqd, int ioprio_class, int ioprio)
 }
 
 static struct cfq_queue *
-cfq_get_queue(struct cfq_data *cfqd, int is_sync, struct task_struct *tsk,
+cfq_get_queue(struct cfq_data *cfqd, int is_sync, struct io_context *ioc,
               gfp_t gfp_mask)
 {
-        const int ioprio = task_ioprio(tsk);
-        const int ioprio_class = task_ioprio_class(tsk);
+        const int ioprio = task_ioprio(ioc);
+        const int ioprio_class = task_ioprio_class(ioc);
         struct cfq_queue **async_cfqq = NULL;
         struct cfq_queue *cfqq = NULL;
 
@@ -1453,7 +1452,7 @@ cfq_get_queue(struct cfq_data *cfqd, int is_sync, struct task_struct *tsk,
         }
 
         if (!cfqq) {
-                cfqq = cfq_find_alloc_queue(cfqd, is_sync, tsk, gfp_mask);
+                cfqq = cfq_find_alloc_queue(cfqd, is_sync, ioc, gfp_mask);
                 if (!cfqq)
                         return NULL;
         }
@@ -1793,7 +1792,7 @@ static void cfq_insert_request(struct request_queue *q, struct request *rq)
         struct cfq_data *cfqd = q->elevator->elevator_data;
         struct cfq_queue *cfqq = RQ_CFQQ(rq);
 
-        cfq_init_prio_data(cfqq);
+        cfq_init_prio_data(cfqq, RQ_CIC(rq)->ioc);
 
         cfq_add_rq_rb(rq);
 
@@ -1900,7 +1899,7 @@ static int cfq_may_queue(struct request_queue *q, int rw)
 
         cfqq = cic_to_cfqq(cic, rw & REQ_RW_SYNC);
         if (cfqq) {
-                cfq_init_prio_data(cfqq);
+                cfq_init_prio_data(cfqq, cic->ioc);
                 cfq_prio_boost(cfqq);
 
                 return __cfq_may_queue(cfqq);
@@ -1938,7 +1937,6 @@ static int
 cfq_set_request(struct request_queue *q, struct request *rq, gfp_t gfp_mask)
 {
         struct cfq_data *cfqd = q->elevator->elevator_data;
-        struct task_struct *tsk = current;
         struct cfq_io_context *cic;
         const int rw = rq_data_dir(rq);
         const int is_sync = rq_is_sync(rq);
@@ -1956,7 +1954,7 @@ cfq_set_request(struct request_queue *q, struct request *rq, gfp_t gfp_mask)
 
         cfqq = cic_to_cfqq(cic, is_sync);
         if (!cfqq) {
-                cfqq = cfq_get_queue(cfqd, is_sync, tsk, gfp_mask);
+                cfqq = cfq_get_queue(cfqd, is_sync, cic->ioc, gfp_mask);
 
                 if (!cfqq)
                         goto queue_fail;
diff --git a/block/ll_rw_blk.c b/block/ll_rw_blk.c
index 3d0422f48453..b9bb02e845cd 100644
--- a/block/ll_rw_blk.c
+++ b/block/ll_rw_blk.c
@@ -3904,6 +3904,26 @@ void exit_io_context(void)
         put_io_context(ioc);
 }
 
+struct io_context *alloc_io_context(gfp_t gfp_flags, int node)
+{
+        struct io_context *ret;
+
+        ret = kmem_cache_alloc_node(iocontext_cachep, gfp_flags, node);
+        if (ret) {
+                atomic_set(&ret->refcount, 1);
+                ret->task = current;
+                ret->ioprio_changed = 0;
+                ret->ioprio = 0;
+                ret->last_waited = jiffies; /* doesn't matter... */
+                ret->nr_batch_requests = 0; /* because this is 0 */
+                ret->aic = NULL;
+                ret->cic_root.rb_node = NULL;
+                ret->ioc_data = NULL;
+        }
+
+        return ret;
+}
+
 /*
  * If the current task has no IO context then create one and initialise it.
  * Otherwise, return its existing IO context.
@@ -3921,16 +3941,8 @@ static struct io_context *current_io_context(gfp_t gfp_flags, int node)
         if (likely(ret))
                 return ret;
 
-        ret = kmem_cache_alloc_node(iocontext_cachep, gfp_flags, node);
+        ret = alloc_io_context(gfp_flags, node);
         if (ret) {
-                atomic_set(&ret->refcount, 1);
-                ret->task = current;
-                ret->ioprio_changed = 0;
-                ret->last_waited = jiffies; /* doesn't matter... */
-                ret->nr_batch_requests = 0; /* because this is 0 */
-                ret->aic = NULL;
-                ret->cic_root.rb_node = NULL;
-                ret->ioc_data = NULL;
                 /* make sure set_task_ioprio() sees the settings above */
                 smp_wmb();
                 tsk->io_context = ret;