dm stats: add support for request-based DM devices

This makes it possible to use dm stats with DM multipath.

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>

2 files changed, 26 insertions, 5 deletions

diff --git a/drivers/md/dm-stats.c b/drivers/md/dm-stats.c
index faf1071ef631..8a8b48fa901a 100644
--- a/drivers/md/dm-stats.c
+++ b/drivers/md/dm-stats.c
@@ -1155,11 +1155,6 @@ int dm_stats_message(struct mapped_device *md, unsigned argc, char **argv,
 {
         int r;
 
-        if (dm_request_based(md)) {
-                DMWARN("Statistics are only supported for bio-based devices");
-                return -EOPNOTSUPP;
-        }
-
         /* All messages here must start with '@' */
         if (!strcasecmp(argv[0], "@stats_create"))
                 r = message_stats_create(md, argc, argv, result, maxlen);
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 767bce906588..90dc49e3c78f 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -86,6 +86,9 @@ struct dm_rq_target_io {
         struct kthread_work work;
         int error;
         union map_info info;
+        struct dm_stats_aux stats_aux;
+        unsigned long duration_jiffies;
+        unsigned n_sectors;
 };
 
 /*
@@ -995,6 +998,17 @@ static struct dm_rq_target_io *tio_from_request(struct request *rq)
         return (rq->q->mq_ops ? blk_mq_rq_to_pdu(rq) : rq->special);
 }
 
+static void rq_end_stats(struct mapped_device *md, struct request *orig)
+{
+        if (unlikely(dm_stats_used(&md->stats))) {
+                struct dm_rq_target_io *tio = tio_from_request(orig);
+                tio->duration_jiffies = jiffies - tio->duration_jiffies;
+                dm_stats_account_io(&md->stats, orig->cmd_flags, blk_rq_pos(orig),
+                                    tio->n_sectors, true, tio->duration_jiffies,
+                                    &tio->stats_aux);
+        }
+}
+
 /*
  * Don't touch any member of the md after calling this function because
  * the md may be freed in dm_put() at the end of this function.
@@ -1078,6 +1092,7 @@ static void dm_end_request(struct request *clone, int error)
         }
 
         free_rq_clone(clone);
+        rq_end_stats(md, rq);
         if (!rq->q->mq_ops)
                 blk_end_request_all(rq, error);
         else
@@ -1120,6 +1135,7 @@ static void dm_requeue_original_request(struct mapped_device *md,
 
         dm_unprep_request(rq);
 
+        rq_end_stats(md, rq);
         if (!rq->q->mq_ops)
                 old_requeue_request(rq);
         else {
@@ -1211,6 +1227,7 @@ static void dm_softirq_done(struct request *rq)
         int rw;
 
         if (!clone) {
+                rq_end_stats(tio->md, rq);
                 rw = rq_data_dir(rq);
                 if (!rq->q->mq_ops) {
                         blk_end_request_all(rq, tio->error);
@@ -1943,6 +1960,14 @@ static void dm_start_request(struct mapped_device *md, struct request *orig)
                 md->last_rq_start_time = ktime_get();
         }
 
+        if (unlikely(dm_stats_used(&md->stats))) {
+                struct dm_rq_target_io *tio = tio_from_request(orig);
+                tio->duration_jiffies = jiffies;
+                tio->n_sectors = blk_rq_sectors(orig);
+                dm_stats_account_io(&md->stats, orig->cmd_flags, blk_rq_pos(orig),
+                                    tio->n_sectors, false, 0, &tio->stats_aux);
+        }
+
         /*
          * Hold the md reference here for the in-flight I/O.
          * We can't rely on the reference count by device opener,
@@ -2689,6 +2714,7 @@ static int dm_mq_queue_rq(struct blk_mq_hw_ctx *hctx,
                 /* Direct call is fine since .queue_rq allows allocations */
                 if (map_request(tio, rq, md) == DM_MAPIO_REQUEUE) {
                         /* Undo dm_start_request() before requeuing */
+                        rq_end_stats(md, rq);
                         rq_completed(md, rq_data_dir(rq), false);
                         return BLK_MQ_RQ_QUEUE_BUSY;
                 }