Put back devstat support that was lost during GEOM transition. Initially,

I've tried to move md(4) to use geom_disk class, like real disks do, but
this requires major rework of some of the existing features such as
configuration dumping for example. Therefore just putting devstat support
directly into md(4) seems to be optimal solution.

Now you can see md(4) stats in `systat -vm' again.

MFC after:	2 weeks

1 files changed, 12 insertions, 0 deletions

diff --git a/sys/dev/md/md.c b/sys/dev/md/md.c
index 2d63fed..b5cc37c 100644
--- a/sys/dev/md/md.c
+++ b/sys/dev/md/md.c
@@ -60,6 +60,7 @@
 #include <sys/systm.h>
 #include <sys/bio.h>
 #include <sys/conf.h>
+#include <sys/devicestat.h>
 #include <sys/fcntl.h>
 #include <sys/kernel.h>
 #include <sys/kthread.h>
@@ -181,6 +182,7 @@ struct md_s {
 	struct g_geom *gp;
 	struct g_provider *pp;
 	int (*start)(struct md_s *sc, struct bio *bp);
+	struct devstat *devstat;
 
 	/* MD_MALLOC related fields */
 	struct indir *indir;
@@ -392,6 +394,8 @@ g_md_start(struct bio *bp)
 	struct md_s *sc;
 
 	sc = bp->bio_to->geom->softc;
+	if ((bp->bio_cmd == BIO_READ) || (bp->bio_cmd == BIO_WRITE))
+		devstat_start_transaction_bio(sc->devstat, bp);
 	mtx_lock(&sc->queue_mtx);
 	bioq_disksort(&sc->bio_queue, bp);
 	mtx_unlock(&sc->queue_mtx);
@@ -725,6 +729,8 @@ md_kthread(void *arg)
 		if (error != -1) {
 			bp->bio_completed = bp->bio_length;
 			g_io_deliver(bp, error);
+			if ((bp->bio_cmd == BIO_READ) || (bp->bio_cmd == BIO_WRITE))
+				devstat_end_transaction_bio(sc->devstat, bp);
 		}
 	}
 }
@@ -792,6 +798,8 @@ mdinit(struct md_s *sc)
 	sc->pp = pp;
 	g_error_provider(pp, 0);
 	g_topology_unlock();
+	sc->devstat = devstat_new_entry("md", sc->unit, sc->sectorsize,
+	    DEVSTAT_ALL_SUPPORTED, DEVSTAT_TYPE_DIRECT, DEVSTAT_PRIORITY_MAX);
 }
 
 /*
@@ -963,6 +971,10 @@ mddestroy(struct md_s *sc, struct thread *td)
 		sc->gp = NULL;
 		sc->pp = NULL;
 	}
+	if (sc->devstat) {
+		devstat_remove_entry(sc->devstat);
+		sc->devstat = NULL;
+	}
 	mtx_lock(&sc->queue_mtx);
 	sc->flags |= MD_SHUTDOWN;
 	wakeup(sc);