block: change the request allocation/congestion logic to be sync/async based

This makes sure that we never wait on async IO for sync requests, instead
of doing the split on writes vs reads.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

3 files changed, 56 insertions, 56 deletions

diff --git a/block/blk-core.c b/block/blk-core.c
index 996ed906d8ca..a32b571aaaa2 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -484,11 +484,11 @@ static int blk_init_free_list(struct request_queue *q)
 {
         struct request_list *rl = &q->rq;
 
-        rl->count[READ] = rl->count[WRITE] = 0;
-        rl->starved[READ] = rl->starved[WRITE] = 0;
+        rl->count[BLK_RW_SYNC] = rl->count[BLK_RW_ASYNC] = 0;
+        rl->starved[BLK_RW_SYNC] = rl->starved[BLK_RW_ASYNC] = 0;
         rl->elvpriv = 0;
-        init_waitqueue_head(&rl->wait[READ]);
-        init_waitqueue_head(&rl->wait[WRITE]);
+        init_waitqueue_head(&rl->wait[BLK_RW_SYNC]);
+        init_waitqueue_head(&rl->wait[BLK_RW_ASYNC]);
 
         rl->rq_pool = mempool_create_node(BLKDEV_MIN_RQ, mempool_alloc_slab,
                                 mempool_free_slab, request_cachep, q->node);
@@ -699,18 +699,18 @@ static void ioc_set_batching(struct request_queue *q, struct io_context *ioc)
         ioc->last_waited = jiffies;
 }
 
-static void __freed_request(struct request_queue *q, int rw)
+static void __freed_request(struct request_queue *q, int sync)
 {
         struct request_list *rl = &q->rq;
 
-        if (rl->count[rw] < queue_congestion_off_threshold(q))
-                blk_clear_queue_congested(q, rw);
+        if (rl->count[sync] < queue_congestion_off_threshold(q))
+                blk_clear_queue_congested(q, sync);
 
-        if (rl->count[rw] + 1 <= q->nr_requests) {
-                if (waitqueue_active(&rl->wait[rw]))
-                        wake_up(&rl->wait[rw]);
+        if (rl->count[sync] + 1 <= q->nr_requests) {
+                if (waitqueue_active(&rl->wait[sync]))
+                        wake_up(&rl->wait[sync]);
 
-                blk_clear_queue_full(q, rw);
+                blk_clear_queue_full(q, sync);
         }
 }
 
@@ -718,18 +718,18 @@ static void __freed_request(struct request_queue *q, int rw)
  * A request has just been released.  Account for it, update the full and
  * congestion status, wake up any waiters.   Called under q->queue_lock.
  */
-static void freed_request(struct request_queue *q, int rw, int priv)
+static void freed_request(struct request_queue *q, int sync, int priv)
 {
         struct request_list *rl = &q->rq;
 
-        rl->count[rw]--;
+        rl->count[sync]--;
         if (priv)
                 rl->elvpriv--;
 
-        __freed_request(q, rw);
+        __freed_request(q, sync);
 
-        if (unlikely(rl->starved[rw ^ 1]))
-                __freed_request(q, rw ^ 1);
+        if (unlikely(rl->starved[sync ^ 1]))
+                __freed_request(q, sync ^ 1);
 }
 
 /*
@@ -743,15 +743,15 @@ static struct request *get_request(struct request_queue *q, int rw_flags,
         struct request *rq = NULL;
         struct request_list *rl = &q->rq;
         struct io_context *ioc = NULL;
-        const int rw = rw_flags & 0x01;
+        const bool is_sync = rw_is_sync(rw_flags) != 0;
         int may_queue, priv;
 
         may_queue = elv_may_queue(q, rw_flags);
         if (may_queue == ELV_MQUEUE_NO)
                 goto rq_starved;
 
-        if (rl->count[rw]+1 >= queue_congestion_on_threshold(q)) {
-                if (rl->count[rw]+1 >= q->nr_requests) {
+        if (rl->count[is_sync]+1 >= queue_congestion_on_threshold(q)) {
+                if (rl->count[is_sync]+1 >= q->nr_requests) {
                         ioc = current_io_context(GFP_ATOMIC, q->node);
                         /*
                          * The queue will fill after this allocation, so set
@@ -759,9 +759,9 @@ static struct request *get_request(struct request_queue *q, int rw_flags,
                          * This process will be allowed to complete a batch of
                          * requests, others will be blocked.
                          */
-                        if (!blk_queue_full(q, rw)) {
+                        if (!blk_queue_full(q, is_sync)) {
                                 ioc_set_batching(q, ioc);
-                                blk_set_queue_full(q, rw);
+                                blk_set_queue_full(q, is_sync);
                         } else {
                                 if (may_queue != ELV_MQUEUE_MUST
                                                 && !ioc_batching(q, ioc)) {
@@ -774,7 +774,7 @@ static struct request *get_request(struct request_queue *q, int rw_flags,
                                 }
                         }
                 }
-                blk_set_queue_congested(q, rw);
+                blk_set_queue_congested(q, is_sync);
         }
 
         /*
@@ -782,11 +782,11 @@ static struct request *get_request(struct request_queue *q, int rw_flags,
          * limit of requests, otherwise we could have thousands of requests
          * allocated with any setting of ->nr_requests
          */
-        if (rl->count[rw] >= (3 * q->nr_requests / 2))
+        if (rl->count[is_sync] >= (3 * q->nr_requests / 2))
                 goto out;
 
-        rl->count[rw]++;
-        rl->starved[rw] = 0;
+        rl->count[is_sync]++;
+        rl->starved[is_sync] = 0;
 
         priv = !test_bit(QUEUE_FLAG_ELVSWITCH, &q->queue_flags);
         if (priv)
@@ -804,7 +804,7 @@ static struct request *get_request(struct request_queue *q, int rw_flags,
                  * wait queue, but this is pretty rare.
                  */
                 spin_lock_irq(q->queue_lock);
-                freed_request(q, rw, priv);
+                freed_request(q, is_sync, priv);
 
                 /*
                  * in the very unlikely event that allocation failed and no
@@ -814,8 +814,8 @@ static struct request *get_request(struct request_queue *q, int rw_flags,
                  * rq mempool into READ and WRITE
                  */
 rq_starved:
-                if (unlikely(rl->count[rw] == 0))
-                        rl->starved[rw] = 1;
+                if (unlikely(rl->count[is_sync] == 0))
+                        rl->starved[is_sync] = 1;
 
                 goto out;
         }
@@ -829,7 +829,7 @@ rq_starved:
         if (ioc_batching(q, ioc))
                 ioc->nr_batch_requests--;
 
-        trace_block_getrq(q, bio, rw);
+        trace_block_getrq(q, bio, rw_flags & 1);
 out:
         return rq;
 }
@@ -843,7 +843,7 @@ out:
 static struct request *get_request_wait(struct request_queue *q, int rw_flags,
                                         struct bio *bio)
 {
-        const int rw = rw_flags & 0x01;
+        const bool is_sync = rw_is_sync(rw_flags) != 0;
         struct request *rq;
 
         rq = get_request(q, rw_flags, bio, GFP_NOIO);
@@ -852,10 +852,10 @@ static struct request *get_request_wait(struct request_queue *q, int rw_flags,
                 struct io_context *ioc;
                 struct request_list *rl = &q->rq;
 
-                prepare_to_wait_exclusive(&rl->wait[rw], &wait,
+                prepare_to_wait_exclusive(&rl->wait[is_sync], &wait,
                                 TASK_UNINTERRUPTIBLE);
 
-                trace_block_sleeprq(q, bio, rw);
+                trace_block_sleeprq(q, bio, rw_flags & 1);
 
                 __generic_unplug_device(q);
                 spin_unlock_irq(q->queue_lock);
@@ -871,7 +871,7 @@ static struct request *get_request_wait(struct request_queue *q, int rw_flags,
                 ioc_set_batching(q, ioc);
 
                 spin_lock_irq(q->queue_lock);
-                finish_wait(&rl->wait[rw], &wait);
+                finish_wait(&rl->wait[is_sync], &wait);
 
                 rq = get_request(q, rw_flags, bio, GFP_NOIO);
         };
@@ -1070,14 +1070,14 @@ void __blk_put_request(struct request_queue *q, struct request *req)
          * it didn't come out of our reserved rq pools
          */
         if (req->cmd_flags & REQ_ALLOCED) {
-                int rw = rq_data_dir(req);
+                int is_sync = rq_is_sync(req) != 0;
                 int priv = req->cmd_flags & REQ_ELVPRIV;
 
                 BUG_ON(!list_empty(&req->queuelist));
                 BUG_ON(!hlist_unhashed(&req->hash));
 
                 blk_free_request(q, req);
-                freed_request(q, rw, priv);
+                freed_request(q, is_sync, priv);
         }
 }
 EXPORT_SYMBOL_GPL(__blk_put_request);
diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c
index e29ddfc73cf4..3ff9bba3379a 100644
--- a/block/blk-sysfs.c
+++ b/block/blk-sysfs.c
@@ -48,28 +48,28 @@ queue_requests_store(struct request_queue *q, const char *page, size_t count)
         q->nr_requests = nr;
         blk_queue_congestion_threshold(q);
 
-        if (rl->count[READ] >= queue_congestion_on_threshold(q))
-                blk_set_queue_congested(q, READ);
-        else if (rl->count[READ] < queue_congestion_off_threshold(q))
-                blk_clear_queue_congested(q, READ);
-
-        if (rl->count[WRITE] >= queue_congestion_on_threshold(q))
-                blk_set_queue_congested(q, WRITE);
-        else if (rl->count[WRITE] < queue_congestion_off_threshold(q))
-                blk_clear_queue_congested(q, WRITE);
-
-        if (rl->count[READ] >= q->nr_requests) {
-                blk_set_queue_full(q, READ);
-        } else if (rl->count[READ]+1 <= q->nr_requests) {
-                blk_clear_queue_full(q, READ);
-                wake_up(&rl->wait[READ]);
+        if (rl->count[BLK_RW_SYNC] >= queue_congestion_on_threshold(q))
+                blk_set_queue_congested(q, BLK_RW_SYNC);
+        else if (rl->count[BLK_RW_SYNC] < queue_congestion_off_threshold(q))
+                blk_clear_queue_congested(q, BLK_RW_SYNC);
+
+        if (rl->count[BLK_RW_ASYNC] >= queue_congestion_on_threshold(q))
+                blk_set_queue_congested(q, BLK_RW_ASYNC);
+        else if (rl->count[BLK_RW_ASYNC] < queue_congestion_off_threshold(q))
+                blk_clear_queue_congested(q, BLK_RW_ASYNC);
+
+        if (rl->count[BLK_RW_SYNC] >= q->nr_requests) {
+                blk_set_queue_full(q, BLK_RW_SYNC);
+        } else if (rl->count[BLK_RW_SYNC]+1 <= q->nr_requests) {
+                blk_clear_queue_full(q, BLK_RW_SYNC);
+                wake_up(&rl->wait[BLK_RW_SYNC]);
         }
 
-        if (rl->count[WRITE] >= q->nr_requests) {
-                blk_set_queue_full(q, WRITE);
-        } else if (rl->count[WRITE]+1 <= q->nr_requests) {
-                blk_clear_queue_full(q, WRITE);
-                wake_up(&rl->wait[WRITE]);
+        if (rl->count[BLK_RW_ASYNC] >= q->nr_requests) {
+                blk_set_queue_full(q, BLK_RW_ASYNC);
+        } else if (rl->count[BLK_RW_ASYNC]+1 <= q->nr_requests) {
+                blk_clear_queue_full(q, BLK_RW_ASYNC);
+                wake_up(&rl->wait[BLK_RW_ASYNC]);
         }
         spin_unlock_irq(q->queue_lock);
         return ret;
diff --git a/block/elevator.c b/block/elevator.c
index 98259eda0ef6..ca6788a0195a 100644
--- a/block/elevator.c
+++ b/block/elevator.c
@@ -677,7 +677,7 @@ void elv_insert(struct request_queue *q, struct request *rq, int where)
         }
 
         if (unplug_it && blk_queue_plugged(q)) {
-                int nrq = q->rq.count[READ] + q->rq.count[WRITE]
+                int nrq = q->rq.count[BLK_RW_SYNC] + q->rq.count[BLK_RW_ASYNC]
                         - q->in_flight;
 
                 if (nrq >= q->unplug_thresh)