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, 0 insertions, 4 deletions

diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c
index cac4e9febe6a..3ff9bba3379a 100644
--- a/block/blk-sysfs.c
+++ b/block/blk-sysfs.c
@@ -209,14 +209,10 @@ static ssize_t queue_iostats_store(struct request_queue *q, const char *page,
         ssize_t ret = queue_var_store(&stats, page, count);
 
         spin_lock_irq(q->queue_lock);
-        elv_quiesce_start(q);
-
         if (stats)
                 queue_flag_set(QUEUE_FLAG_IO_STAT, q);
         else
                 queue_flag_clear(QUEUE_FLAG_IO_STAT, q);
-
-        elv_quiesce_end(q);
         spin_unlock_irq(q->queue_lock);
 
         return ret;