[patch v2 1/3] block: add a non-queueable flush flag

[shaohua . li]

flush request isn't queueable in some drives. Add a flag to let driver
notify block layer about this. We can optimize flush performance with the
knowledge.

Signed-off-by: Shaohua Li <shaohua.li@xxxxxxxxx>
---
 include/linux/blkdev.h |   11 +++++++++++
 1 file changed, 11 insertions(+)

Index: linux/include/linux/blkdev.h
===================================================================
--- linux.orig/include/linux/blkdev.h	2011-05-04 14:23:42.000000000 +0800
+++ linux/include/linux/blkdev.h	2011-05-04 14:24:40.000000000 +0800
@@ -364,6 +364,7 @@ struct request_queue
 	 * for flush operations
 	 */
 	unsigned int		flush_flags;
+	unsigned int		flush_not_queueable:1;
 	unsigned int		flush_pending_idx:1;
 	unsigned int		flush_running_idx:1;
 	unsigned long		flush_pending_since;
@@ -549,6 +550,16 @@ static inline void blk_clear_queue_full(
 		queue_flag_clear(QUEUE_FLAG_ASYNCFULL, q);
 }
 
+static inline void blk_set_queue_flush_queueable(struct request_queue *q,
+		bool queueable)
+{
+	q->flush_not_queueable = !queueable;
+}
+
+static inline bool blk_queue_flush_queueable(struct request_queue *q)
+{
+	return !q->flush_not_queueable;
+}
 
 /*
  * mergeable request must not have _NOMERGE or _BARRIER bit set, nor may

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