From 484b4061e6683e0e6a09c7455f80781128dc8a6b Mon Sep 17 00:00:00 2001
From: Jens Axboe <axboe@fb.com>
Date: Wed, 21 May 2014 14:01:15 -0600
Subject: [PATCH] blk-mq: save memory by freeing requests on unused hardware
 queues

Depending on the topology of the machine and the number of queues
exposed by a device, we can end up in a situation where some of
the hardware queues are unused (as in, they don't map to any
software queues). For this case, free up the memory used by the
request map, as we will not use it. This can be a substantial
amount of memory, depending on the number of queues vs CPUs and
the queue depth of the device.

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