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>

diff --git a/drivers/md/dm-stats.c b/drivers/md/dm-stats.c
index faf1071..8a8b48f 100644 (file)
--- 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 767bce9..90dc49e 100644 (file)
--- 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;
                }