From d93f28b5423c37d4a884d8c10191c4d738d2b45a Mon Sep 17 00:00:00 2001
From: Tejun Heo <tj@kernel.org>
Date: Mon, 4 Jun 2012 20:40:56 -0700
Subject: [PATCH] --- yaml --- r: 320914 b: refs/heads/master c:
 7f4b35d155a5f9e5748539a79558533aa08d6a81 h: refs/heads/master v: v3

---
 [refs]                     |  2 +-
 trunk/block/blk-core.c     | 42 ++++++++++++++------------------------
 trunk/block/blk-throttle.c |  3 ---
 3 files changed, 16 insertions(+), 31 deletions(-)

diff --git a/[refs] b/[refs]
index d5f6521b7a99..d01b5247d411 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: a06e05e6afab70b4b23c0a7975aaeae24b195cd6
+refs/heads/master: 7f4b35d155a5f9e5748539a79558533aa08d6a81
diff --git a/trunk/block/blk-core.c b/trunk/block/blk-core.c
index 080204a10fcf..71894e143b91 100644
--- a/trunk/block/blk-core.c
+++ b/trunk/block/blk-core.c
@@ -855,15 +855,11 @@ static struct request *__get_request(struct request_queue *q, int rw_flags,
 {
 	struct request *rq;
 	struct request_list *rl = &q->rq;
-	struct elevator_type *et;
-	struct io_context *ioc;
+	struct elevator_type *et = q->elevator->type;
+	struct io_context *ioc = rq_ioc(bio);
 	struct io_cq *icq = NULL;
 	const bool is_sync = rw_is_sync(rw_flags) != 0;
-	bool retried = false;
 	int may_queue;
-retry:
-	et = q->elevator->type;
-	ioc = rq_ioc(bio);
 
 	if (unlikely(blk_queue_dead(q)))
 		return NULL;
@@ -874,20 +870,6 @@ static struct request *__get_request(struct request_queue *q, int rw_flags,
 
 	if (rl->count[is_sync]+1 >= queue_congestion_on_threshold(q)) {
 		if (rl->count[is_sync]+1 >= q->nr_requests) {
-			/*
-			 * We want ioc to record batching state.  If it's
-			 * not already there, creating a new one requires
-			 * dropping queue_lock, which in turn requires
-			 * retesting conditions to avoid queue hang.
-			 */
-			if (!ioc && !retried) {
-				spin_unlock_irq(q->queue_lock);
-				create_io_context(gfp_mask, q->node);
-				spin_lock_irq(q->queue_lock);
-				retried = true;
-				goto retry;
-			}
-
 			/*
 			 * The queue will fill after this allocation, so set
 			 * it as full, and mark this process as "batching".
@@ -955,12 +937,8 @@ static struct request *__get_request(struct request_queue *q, int rw_flags,
 	/* init elvpriv */
 	if (rw_flags & REQ_ELVPRIV) {
 		if (unlikely(et->icq_cache && !icq)) {
-			create_io_context(gfp_mask, q->node);
-			ioc = rq_ioc(bio);
-			if (!ioc)
-				goto fail_elvpriv;
-
-			icq = ioc_create_icq(ioc, q, gfp_mask);
+			if (ioc)
+				icq = ioc_create_icq(ioc, q, gfp_mask);
 			if (!icq)
 				goto fail_elvpriv;
 		}
@@ -1071,7 +1049,6 @@ static struct request *get_request(struct request_queue *q, int rw_flags,
 	 * to allocate at least one request, and up to a big batch of them
 	 * for a small period time.  See ioc_batching, ioc_set_batching
 	 */
-	create_io_context(GFP_NOIO, q->node);
 	ioc_set_batching(q, current->io_context);
 
 	spin_lock_irq(q->queue_lock);
@@ -1086,6 +1063,9 @@ struct request *blk_get_request(struct request_queue *q, int rw, gfp_t gfp_mask)
 
 	BUG_ON(rw != READ && rw != WRITE);
 
+	/* create ioc upfront */
+	create_io_context(gfp_mask, q->node);
+
 	spin_lock_irq(q->queue_lock);
 	rq = get_request(q, rw, NULL, gfp_mask);
 	if (!rq)
@@ -1698,6 +1678,14 @@ generic_make_request_checks(struct bio *bio)
 		goto end_io;
 	}
 
+	/*
+	 * Various block parts want %current->io_context and lazy ioc
+	 * allocation ends up trading a lot of pain for a small amount of
+	 * memory.  Just allocate it upfront.  This may fail and block
+	 * layer knows how to live with it.
+	 */
+	create_io_context(GFP_ATOMIC, q->node);
+
 	if (blk_throtl_bio(q, bio))
 		return false;	/* throttled, will be resubmitted later */
 
diff --git a/trunk/block/blk-throttle.c b/trunk/block/blk-throttle.c
index 5b0659512047..e287c19908c8 100644
--- a/trunk/block/blk-throttle.c
+++ b/trunk/block/blk-throttle.c
@@ -1123,9 +1123,6 @@ bool blk_throtl_bio(struct request_queue *q, struct bio *bio)
 		goto out;
 	}
 
-	/* bio_associate_current() needs ioc, try creating */
-	create_io_context(GFP_ATOMIC, q->node);
-
 	/*
 	 * A throtl_grp pointer retrieved under rcu can be used to access
 	 * basic fields like stats and io rates. If a group has no rules,