[src/trunk]: src/sys/dev/dkwedge dk(4): Omit needless sc_iopend, sc_dkdrn mec...

[riastradh <riastradh%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/2670f5547e4f
branches:  trunk
changeset: 374650:2670f5547e4f
user:      riastradh <riastradh%NetBSD.org@localhost>
date:      Tue May 09 12:49:00 2023 +0000

description:
dk(4): Omit needless sc_iopend, sc_dkdrn mechanism.

vdevgone guarantees that all instances are closed by the time it
returns, which in turn guarantees all I/O operations (read, write,
ioctl, &c.) have completed, and, if the block device is open,
vinvalbuf(V_SAVE) -> vflushbuf has completed, which forces all
buffered transfers to be issued and waits for them to complete.

So by the time vdevgone returns, no further transfers can be
submitted and the bufq must be empty.

diffstat:

 sys/dev/dkwedge/dk.c |  40 ++--------------------------------------
 1 files changed, 2 insertions(+), 38 deletions(-)

diffs (131 lines):

diff -r 0201d8a0d3b9 -r 2670f5547e4f sys/dev/dkwedge/dk.c
--- a/sys/dev/dkwedge/dk.c      Tue May 09 12:04:04 2023 +0000
+++ b/sys/dev/dkwedge/dk.c      Tue May 09 12:49:00 2023 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: dk.c,v 1.154 2023/05/09 12:04:04 riastradh Exp $       */
+/*     $NetBSD: dk.c,v 1.155 2023/05/09 12:49:00 riastradh Exp $       */
 
 /*-
  * Copyright (c) 2004, 2005, 2006, 2007 The NetBSD Foundation, Inc.
@@ -30,7 +30,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: dk.c,v 1.154 2023/05/09 12:04:04 riastradh Exp $");
+__KERNEL_RCSID(0, "$NetBSD: dk.c,v 1.155 2023/05/09 12:49:00 riastradh Exp $");
 
 #ifdef _KERNEL_OPT
 #include "opt_dkwedge.h"
@@ -91,8 +91,6 @@ struct dkwedge_softc {
        struct callout  sc_restart_ch;  /* callout to restart I/O */
 
        kmutex_t        sc_iolock;
-       kcondvar_t      sc_dkdrn;
-       u_int           sc_iopend;      /* I/Os pending */
        bool            sc_iostop;      /* don't schedule restart */
        int             sc_mode;        /* parent open mode */
 };
@@ -198,21 +196,6 @@ dkwedge_attach(device_t parent, device_t
 }
 
 /*
- * dkwedge_wait_drain:
- *
- *     Wait for I/O on the wedge to drain.
- */
-static void
-dkwedge_wait_drain(struct dkwedge_softc *sc)
-{
-
-       mutex_enter(&sc->sc_iolock);
-       while (sc->sc_iopend != 0)
-               cv_wait(&sc->sc_dkdrn, &sc->sc_iolock);
-       mutex_exit(&sc->sc_iolock);
-}
-
-/*
  * dkwedge_compute_pdev:
  *
  *     Compute the parent disk's dev_t.
@@ -441,7 +424,6 @@ dkwedge_add(struct dkwedge_info *dkw)
        callout_setfunc(&sc->sc_restart_ch, dkrestart, sc);
 
        mutex_init(&sc->sc_iolock, MUTEX_DEFAULT, IPL_BIO);
-       cv_init(&sc->sc_dkdrn, "dkdrn");
 
        /*
         * Wedge will be added; increment the wedge count for the parent.
@@ -484,7 +466,6 @@ dkwedge_add(struct dkwedge_info *dkw)
        }
        mutex_exit(&pdk->dk_openlock);
        if (error) {
-               cv_destroy(&sc->sc_dkdrn);
                mutex_destroy(&sc->sc_iolock);
                bufq_free(sc->sc_bufq);
                dkwedge_size_fini(sc);
@@ -542,7 +523,6 @@ dkwedge_add(struct dkwedge_info *dkw)
                LIST_REMOVE(sc, sc_plink);
                mutex_exit(&pdk->dk_openlock);
 
-               cv_destroy(&sc->sc_dkdrn);
                mutex_destroy(&sc->sc_iolock);
                bufq_free(sc->sc_bufq);
                dkwedge_size_fini(sc);
@@ -572,7 +552,6 @@ dkwedge_add(struct dkwedge_info *dkw)
                LIST_REMOVE(sc, sc_plink);
                mutex_exit(&pdk->dk_openlock);
 
-               cv_destroy(&sc->sc_dkdrn);
                mutex_destroy(&sc->sc_iolock);
                bufq_free(sc->sc_bufq);
                dkwedge_size_fini(sc);
@@ -710,14 +689,6 @@ dkwedge_detach(device_t self, int flags)
        mutex_exit(&sc->sc_iolock);
        callout_halt(&sc->sc_restart_ch, NULL);
 
-       /*
-        * dkstart() will kill any queued buffers now that the
-        * state of the wedge is not RUNNING.  Once we've done
-        * that, wait for any other pending I/O to complete.
-        */
-       dkstart(sc);
-       dkwedge_wait_drain(sc);
-
        /* Locate the wedge major numbers. */
        bmaj = bdevsw_lookup_major(&dk_bdevsw);
        cmaj = cdevsw_lookup_major(&dk_cdevsw);
@@ -763,7 +734,6 @@ dkwedge_detach(device_t self, int flags)
        rw_exit(&dkwedges_lock);
 
        mutex_destroy(&sc->sc_iolock);
-       cv_destroy(&sc->sc_dkdrn);
        dkwedge_size_fini(sc);
 
        free(sc, M_DKWEDGE);
@@ -1484,7 +1454,6 @@ dkstrategy(struct buf *bp)
 
        /* Place it in the queue and start I/O on the unit. */
        mutex_enter(&sc->sc_iolock);
-       sc->sc_iopend++;
        disk_wait(&sc->sc_dk);
        bufq_put(sc->sc_bufq, bp);
        mutex_exit(&sc->sc_iolock);
@@ -1514,8 +1483,6 @@ dkstart(struct dkwedge_softc *sc)
        while ((bp = bufq_peek(sc->sc_bufq)) != NULL) {
                if (sc->sc_iostop) {
                        (void) bufq_get(sc->sc_bufq);
-                       if (--sc->sc_iopend == 0)
-                               cv_broadcast(&sc->sc_dkdrn);
                        mutex_exit(&sc->sc_iolock);
                        bp->b_error = ENXIO;
                        bp->b_resid = bp->b_bcount;
@@ -1601,9 +1568,6 @@ dkiodone(struct buf *bp)
        putiobuf(bp);
 
        mutex_enter(&sc->sc_iolock);
-       if (--sc->sc_iopend == 0)
-               cv_broadcast(&sc->sc_dkdrn);
-
        disk_unbusy(&sc->sc_dk, obp->b_bcount - obp->b_resid,
            obp->b_flags & B_READ);
        mutex_exit(&sc->sc_iolock);