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Subject[PATCH] Move the second call to get_request to the end of the loop
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In function get_request_wait, the second call to get_request could be moved to the end of the while loop,
because if the first call to get_request fails, the second call will fail without sleep.

Signed-off-by: Zhang Yanmin <yanmin.zhang@intel.com>

---

--- linux-2.6.26-rc3/block/blk-core.c 2008-05-19 07:17:18.000000000 +0800
+++ linux-2.6.26-rc3_block/block/blk-core.c 2008-05-22 07:00:15.000000000 +0800
@@ -806,35 +806,32 @@ static struct request *get_request_wait(
rq = get_request(q, rw_flags, bio, GFP_NOIO);
while (!rq) {
DEFINE_WAIT(wait);
+ struct io_context *ioc;
struct request_list *rl = &q->rq;

prepare_to_wait_exclusive(&rl->wait[rw], &wait,
TASK_UNINTERRUPTIBLE);

- rq = get_request(q, rw_flags, bio, GFP_NOIO);
-
- if (!rq) {
- struct io_context *ioc;
+ blk_add_trace_generic(q, bio, rw, BLK_TA_SLEEPRQ);

- blk_add_trace_generic(q, bio, rw, BLK_TA_SLEEPRQ);
-
- __generic_unplug_device(q);
- spin_unlock_irq(q->queue_lock);
- io_schedule();
+ __generic_unplug_device(q);
+ spin_unlock_irq(q->queue_lock);
+ io_schedule();

- /*
- * After sleeping, we become a "batching" process and
- * will be able 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
- */
- ioc = current_io_context(GFP_NOIO, q->node);
- ioc_set_batching(q, ioc);
+ /*
+ * After sleeping, we become a "batching" process and
+ * will be able 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
+ */
+ ioc = current_io_context(GFP_NOIO, q->node);
+ ioc_set_batching(q, ioc);

- spin_lock_irq(q->queue_lock);
- }
+ spin_lock_irq(q->queue_lock);
finish_wait(&rl->wait[rw], &wait);
- }
+
+ rq = get_request(q, rw_flags, bio, GFP_NOIO);
+ };

return rq;
}

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