block: Add and use op_stat_group() for indexing disk_stat fields.

Add and use a new op_stat_group() function for indexing partition stat
fields rather than indexing them by rq_data_dir() or bio_data_dir().
This function works similarly to op_is_sync() in that it takes the
request::cmd_flags or bio::bi_opf flags and determines which stats
should et updated.

In addition, the second parameter to generic_start_io_acct() and
generic_end_io_acct() is now a REQ_OP rather than simply a read or
write bit and it uses op_stat_group() on the parameter to determine
the stat group.

Note that the partition in_flight counts are not part of the per-cpu
statistics and as such are not indexed via this function.  It's now
indexed by op_is_write().

tj: Refreshed on top of v4.17.  Updated to pass around REQ_OP.

Signed-off-by: Michael Callahan <michaelcallahan@fb.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Joshua Morris <josh.h.morris@us.ibm.com>
Cc: Philipp Reisner <philipp.reisner@linbit.com>
Cc: Matias Bjorling <mb@lightnvm.io>
Cc: Kent Overstreet <kent.overstreet@gmail.com>
Cc: Alasdair Kergon <agk@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

1 files changed, 2 insertions, 3 deletions

diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index 78c29044684a..2907a8156aaf 100644
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -1277,11 +1277,10 @@ static int zram_bvec_rw(struct zram *zram, struct bio_vec *bvec, u32 index,
                         int offset, unsigned int op, struct bio *bio)
 {
         unsigned long start_time = jiffies;
-        int rw_acct = op_is_write(op) ? REQ_OP_WRITE : REQ_OP_READ;
         struct request_queue *q = zram->disk->queue;
         int ret;
 
-        generic_start_io_acct(q, rw_acct, bvec->bv_len >> SECTOR_SHIFT,
+        generic_start_io_acct(q, op, bvec->bv_len >> SECTOR_SHIFT,
                         &zram->disk->part0);
 
         if (!op_is_write(op)) {
@@ -1293,7 +1292,7 @@ static int zram_bvec_rw(struct zram *zram, struct bio_vec *bvec, u32 index,
                 ret = zram_bvec_write(zram, bvec, index, offset, bio);
         }
 
-        generic_end_io_acct(q, rw_acct, &zram->disk->part0, start_time);
+        generic_end_io_acct(q, op, &zram->disk->part0, start_time);
 
         zram_slot_lock(zram, index);
         zram_accessed(zram, index);