[PATCH 23/60] block: introduce flag QUEUE_FLAG_NO_MP

[Ming Lei]

MD(especially raid1 and raid10) is a bit difficult to support
multipage bvec, so introduce this flag for not enabling multipage
bvec, then MD can still accept singlepage bvec only, and once
direct access to bvec table in MD and other fs/drivers are cleanuped,
the flag can be removed. BTRFS has the similar issue too.

Signed-off-by: Ming Lei <tom.leiming@xxxxxxxxx>
---
 include/linux/blkdev.h | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index c47c358ba052..e4dd25361bd6 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -505,6 +505,7 @@ struct request_queue {
 #define QUEUE_FLAG_FUA	       24	/* device supports FUA writes */
 #define QUEUE_FLAG_FLUSH_NQ    25	/* flush not queueuable */
 #define QUEUE_FLAG_DAX         26	/* device supports DAX */
+#define QUEUE_FLAG_NO_MP       27	/* multipage bvecs isn't ready */
 
 #define QUEUE_FLAG_DEFAULT	((1 << QUEUE_FLAG_IO_STAT) |		\
 				 (1 << QUEUE_FLAG_STACKABLE)	|	\
@@ -595,6 +596,7 @@ static inline void queue_flag_clear(unsigned int flag, struct request_queue *q)
 #define blk_queue_secure_erase(q) \
 	(test_bit(QUEUE_FLAG_SECERASE, &(q)->queue_flags))
 #define blk_queue_dax(q)	test_bit(QUEUE_FLAG_DAX, &(q)->queue_flags)
+#define blk_queue_no_mp(q)	test_bit(QUEUE_FLAG_NO_MP, &(q)->queue_flags)
 
 #define blk_noretry_request(rq) \
 	((rq)->cmd_flags & (REQ_FAILFAST_DEV|REQ_FAILFAST_TRANSPORT| \
-- 
2.7.4