block: simplify I/O stat accounting

This simplifies I/O stat accounting switching code and separates it
completely from I/O scheduler switch code.

Requests are accounted according to the state of their request queue
at the time of the request allocation. There is no need anymore to
flush the request queue when switching I/O accounting state.

Signed-off-by: Jerome Marchand <jmarchan@redhat.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

1 files changed, 3 insertions, 0 deletions

diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index ba54c834a59..2755d5c6da2 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -118,6 +118,7 @@ enum rq_flag_bits {
         __REQ_COPY_USER,        /* contains copies of user pages */
         __REQ_INTEGRITY,        /* integrity metadata has been remapped */
         __REQ_NOIDLE,           /* Don't anticipate more IO after this one */
+        __REQ_IO_STAT,          /* account I/O stat */
         __REQ_NR_BITS,          /* stops here */
 };
 
@@ -145,6 +146,7 @@ enum rq_flag_bits {
 #define REQ_COPY_USER   (1 << __REQ_COPY_USER)
 #define REQ_INTEGRITY   (1 << __REQ_INTEGRITY)
 #define REQ_NOIDLE      (1 << __REQ_NOIDLE)
+#define REQ_IO_STAT     (1 << __REQ_IO_STAT)
 
 #define BLK_MAX_CDB     16
 
@@ -598,6 +600,7 @@ enum {
                                  blk_failfast_transport(rq) ||  \
                                  blk_failfast_driver(rq))
 #define blk_rq_started(rq)      ((rq)->cmd_flags & REQ_STARTED)
+#define blk_rq_io_stat(rq)      ((rq)->cmd_flags & REQ_IO_STAT)
 
 #define blk_account_rq(rq)      (blk_rq_started(rq) && (blk_fs_request(rq) || blk_discard_rq(rq)))