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Date:	Fri, 10 Oct 2014 16:23:09 +0200
From:	Jan Kara <jack@...e.cz>
To:	linux-fsdevel@...r.kernel.org
Cc:	linux-ext4@...r.kernel.org, Dave Chinner <david@...morbit.com>,
	xfs@....sgi.com, cluster-devel@...hat.com,
	Steven Whitehouse <swhiteho@...hat.com>,
	Mark Fasheh <mfasheh@...e.com>,
	Joel Becker <jlbec@...lplan.org>, ocfs2-devel@....oracle.com,
	reiserfs-devel@...r.kernel.org, Jeff Mahoney <jeffm@...e.de>,
	Dave Kleikamp <shaggy@...nel.org>,
	jfs-discussion@...ts.sourceforge.net, tytso@....edu,
	viro@...iv.linux.org.uk, Tao Ma <boyu.mt@...bao.com>,
	Christoph Hellwig <hch@...radead.org>,
	Roland Dreier <roland@...estorage.com>,
	Dan Williams <dan.j.williams@...el.com>,
	Jens Axboe <jaxboe@...ionio.com>
Subject: [PATCH] block: Make rq_affinity = 1 work as expected

From: Tao Ma <boyu.mt@...bao.com>

Commit 5757a6d76c introduced a new rq_affinity = 2 so as to make
the request completed in the __make_request cpu. But it makes the
old rq_affinity = 1 not work any more. The root cause is that
if the 'cpu' and 'req->cpu' is in the same group and cpu != req->cpu,
ccpu will be the same as group_cpu, so the completion will be
excuted in the 'cpu' not 'group_cpu'.

This patch fix problem by simpling removing group_cpu and the codes
are more explicit now. If ccpu == cpu, we complete in cpu, otherwise
we raise_blk_irq to ccpu.

Cc: Christoph Hellwig <hch@...radead.org>
Cc: Roland Dreier <roland@...estorage.com>
Cc: Dan Williams <dan.j.williams@...el.com>
Cc: Jens Axboe <jaxboe@...ionio.com>
Signed-off-by: Tao Ma <boyu.mt@...bao.com>
Reviewed-by: Shaohua Li <shaohua.li@...el.com>
Signed-off-by: Jens Axboe <jaxboe@...ionio.com>
---
 block/blk-softirq.c | 8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/block/blk-softirq.c b/block/blk-softirq.c
index 475fab809a80..487addc85bb5 100644
--- a/block/blk-softirq.c
+++ b/block/blk-softirq.c
@@ -103,7 +103,7 @@ static struct notifier_block __cpuinitdata blk_cpu_notifier = {
 
 void __blk_complete_request(struct request *req)
 {
-	int ccpu, cpu, group_cpu = NR_CPUS;
+	int ccpu, cpu;
 	struct request_queue *q = req->q;
 	unsigned long flags;
 
@@ -117,14 +117,12 @@ void __blk_complete_request(struct request *req)
 	 */
 	if (test_bit(QUEUE_FLAG_SAME_COMP, &q->queue_flags) && req->cpu != -1) {
 		ccpu = req->cpu;
-		if (!test_bit(QUEUE_FLAG_SAME_FORCE, &q->queue_flags)) {
+		if (!test_bit(QUEUE_FLAG_SAME_FORCE, &q->queue_flags))
 			ccpu = blk_cpu_to_group(ccpu);
-			group_cpu = blk_cpu_to_group(cpu);
-		}
 	} else
 		ccpu = cpu;
 
-	if (ccpu == cpu || ccpu == group_cpu) {
+	if (ccpu == cpu) {
 		struct list_head *list;
 do_local:
 		list = &__get_cpu_var(blk_cpu_done);
-- 
1.8.1.4

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