The commit is pushed to "branch-rh7-3.10.0-229.7.2.vz7.9.x-ovz" and will appear 
at https://src.openvz.org/scm/ovz/vzkernel.git
after rh7-3.10.0-229.7.2.vz7.9.12
------>
commit dcd21871f74e0faa10982e8de34661671c126556
Author: Tejun Heo <t...@kernel.org>
Date:   Mon Nov 23 19:30:36 2015 +0400

    ms/cfq-iosched: simplify control flow in cfq_get_queue()
    
    cfq_get_queue()'s control flow looks like the following.
    
        async_cfqq = NULL;
        cfqq = NULL;
    
        if (!is_sync) {
                ...
                async_cfqq = ...;
                cfqq = *async_cfqq;
        }
    
        if (!cfqq)
                cfqq = ...;
    
        if (!is_sync && !(*async_cfqq))
                ...;
    
    The only thing the local variable init, the second if, and the
    async_cfqq test in the third if achieves is to skip cfqq creation and
    installation if *async_cfqq was already non-NULL.  This is needlessly
    complicated with different tests examining the same condition.
    Simplify it to the following.
    
        if (!is_sync) {
                ...
                async_cfqq = ...;
                cfqq = *async_cfqq;
                if (cfqq)
                        goto out;
        }
    
        cfqq = ...;
    
        if (!is_sync)
                ...;
     out:
    
    Signed-off-by: Tejun Heo <t...@kernel.org>
    Acked-by: Jeff Moyer <jmo...@redhat.com>
    Cc: Vivek Goyal <vgo...@redhat.com>
    Cc: Arianna Avanzini <avanzini.aria...@gmail.com>
    Signed-off-by: Jens Axboe <ax...@fb.com>
    
    https://jira.sw.ru/browse/PSBM-41334
    
    (cherry picked from commit 4ebc1c61d6185604c97fd0b0355ab668052044ab)
    Signed-off-by: Andrey Ryabinin <aryabi...@virtuozzo.com>
---
 block/cfq-iosched.c | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index 987c0f9..a4149c3 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -3696,25 +3696,26 @@ cfq_get_queue(struct cfq_data *cfqd, bool is_sync, 
struct cfq_io_cq *cic,
 {
        const int ioprio_class = IOPRIO_PRIO_CLASS(cic->ioprio);
        const int ioprio = IOPRIO_PRIO_DATA(cic->ioprio);
-       struct cfq_queue **async_cfqq = NULL;
-       struct cfq_queue *cfqq = NULL;
+       struct cfq_queue **async_cfqq;
+       struct cfq_queue *cfqq;
 
        if (!is_sync) {
                async_cfqq = cfq_async_queue_prio(cfqd, ioprio_class, ioprio);
                cfqq = *async_cfqq;
+               if (cfqq)
+                       goto out;
        }
 
-       if (!cfqq)
-               cfqq = cfq_find_alloc_queue(cfqd, is_sync, cic, bio);
+       cfqq = cfq_find_alloc_queue(cfqd, is_sync, cic, bio);
 
        /*
         * pin the queue now that it's allocated, scheduler exit will prune it
         */
-       if (!is_sync && !(*async_cfqq)) {
+       if (!is_sync) {
                cfqq->ref++;
                *async_cfqq = cfqq;
        }
-
+out:
        cfqq->ref++;
        return cfqq;
 }
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