block: separate priority boosting from REQ_META

Add a new REQ_PRIO to let requests preempt others in the cfq I/O schedule,
and lave REQ_META purely for marking requests as metadata in blktrace.

All existing callers of REQ_META except for XFS are updated to also
set REQ_PRIO for now.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Namhyung Kim <namhyung@gmail.com>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>

1 files changed, 4 insertions, 2 deletions

diff --git a/include/linux/blk_types.h b/include/linux/blk_types.h
index 32f0076e844b..71fc53bb8f1c 100644
--- a/include/linux/blk_types.h
+++ b/include/linux/blk_types.h
@@ -124,6 +124,7 @@ enum rq_flag_bits {
 
         __REQ_SYNC,             /* request is sync (sync write or read) */
         __REQ_META,             /* metadata io request */
+        __REQ_PRIO,             /* boost priority in cfq */
         __REQ_DISCARD,          /* request to discard sectors */
         __REQ_SECURE,           /* secure discard (used with __REQ_DISCARD) */
 
@@ -161,14 +162,15 @@ enum rq_flag_bits {
 #define REQ_FAILFAST_DRIVER     (1 << __REQ_FAILFAST_DRIVER)
 #define REQ_SYNC                (1 << __REQ_SYNC)
 #define REQ_META                (1 << __REQ_META)
+#define REQ_PRIO                (1 << __REQ_PRIO)
 #define REQ_DISCARD             (1 << __REQ_DISCARD)
 #define REQ_NOIDLE              (1 << __REQ_NOIDLE)
 
 #define REQ_FAILFAST_MASK \
         (REQ_FAILFAST_DEV | REQ_FAILFAST_TRANSPORT | REQ_FAILFAST_DRIVER)
 #define REQ_COMMON_MASK \
-        (REQ_WRITE | REQ_FAILFAST_MASK | REQ_SYNC | REQ_META | REQ_DISCARD | \
-         REQ_NOIDLE | REQ_FLUSH | REQ_FUA | REQ_SECURE)
+        (REQ_WRITE | REQ_FAILFAST_MASK | REQ_SYNC | REQ_META | REQ_PRIO | \
+         REQ_DISCARD | REQ_NOIDLE | REQ_FLUSH | REQ_FUA | REQ_SECURE)
 #define REQ_CLONE_MASK          REQ_COMMON_MASK
 
 #define REQ_RAHEAD              (1 << __REQ_RAHEAD)