block: add REQ_BACKGROUND

This adds a new request flag, REQ_BACKGROUND, that callers can use to
tell the block layer that this is background (non-urgent) IO.

Signed-off-by: Jens Axboe <axboe@fb.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>

1 files changed, 2 insertions, 0 deletions

diff --git a/include/linux/blk_types.h b/include/linux/blk_types.h
index bb921028e7c5..562ac46cb790 100644
--- a/include/linux/blk_types.h
+++ b/include/linux/blk_types.h
@@ -177,6 +177,7 @@ enum req_flag_bits {
         __REQ_FUA,              /* forced unit access */
         __REQ_PREFLUSH,         /* request for cache flush */
         __REQ_RAHEAD,           /* read ahead, can fail anytime */
+        __REQ_BACKGROUND,       /* background IO */
         __REQ_NR_BITS,          /* stops here */
 };
 
@@ -192,6 +193,7 @@ enum req_flag_bits {
 #define REQ_FUA                 (1ULL << __REQ_FUA)
 #define REQ_PREFLUSH            (1ULL << __REQ_PREFLUSH)
 #define REQ_RAHEAD              (1ULL << __REQ_RAHEAD)
+#define REQ_BACKGROUND          (1ULL << __REQ_BACKGROUND)
 
 #define REQ_FAILFAST_MASK \
         (REQ_FAILFAST_DEV | REQ_FAILFAST_TRANSPORT | REQ_FAILFAST_DRIVER)