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/*-
* Copyright (c) 2003 Poul-Henning Kamp
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. The names of the authors may not be used to endorse or promote
* products derived from this software without specific prior written
* permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* $FreeBSD: src/sys/geom/geom_fox.c,v 1.3 2003/10/24 18:46:23 phk Exp $
*
* This is a GEOM module for handling path selection for multi-path
* storage devices. It is named "fox" because it, like they, prefer
* to have multiple exits to choose from.
*
*/
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/conf.h>
#include <sys/bio.h>
#include <sys/malloc.h>
#include <sys/lock.h>
#include <sys/mutex.h>
#include <sys/libkern.h>
#include <sys/endian.h>
#include <sys/md5.h>
#include <sys/errno.h>
#include <geom/geom.h>
#define FOX_CLASS_NAME "FOX"
#define FOX_MAGIC "GEOM::FOX"
struct g_fox_softc {
off_t mediasize;
u_int sectorsize;
TAILQ_HEAD(, bio) queue;
struct mtx lock;
u_char magic[16];
struct g_consumer *path;
struct g_consumer *opath;
int waiting;
int cr, cw, ce;
};
/*
* This function is called whenever we need to select a new path.
*/
static void
g_fox_select_path(void *arg, int flag)
{
struct g_geom *gp;
struct g_fox_softc *sc;
struct g_consumer *cp1;
struct bio *bp;
int error;
g_topology_assert();
if (flag == EV_CANCEL)
return;
gp = arg;
sc = gp->softc;
if (sc->opath != NULL) {
/*
* First, close the old path entirely.
*/
printf("Closing old path (%s) on fox (%s)\n",
sc->opath->provider->name, gp->name);
cp1 = LIST_NEXT(sc->opath, consumer);
error = g_access_rel(sc->opath, -sc->cr, -sc->cw, -(sc->ce + 1));
KASSERT(error == 0, ("Failed close of old path %d", error));
/*
* The attempt to reopen it with a exclusive count
*/
error = g_access_rel(sc->opath, 0, 0, 1);
if (error) {
/*
* Ok, ditch this consumer, we can't use it.
*/
printf("Drop old path (%s) on fox (%s)\n",
sc->opath->provider->name, gp->name);
g_detach(sc->opath);
g_destroy_consumer(sc->opath);
if (LIST_EMPTY(&gp->consumer)) {
/* No consumers left */
g_wither_geom(gp, ENXIO);
for (;;) {
bp = TAILQ_FIRST(&sc->queue);
if (bp == NULL)
break;
TAILQ_REMOVE(&sc->queue, bp, bio_queue);
bp->bio_error = ENXIO;
g_std_done(bp);
}
return;
}
} else {
printf("Got e-bit on old path (%s) on fox (%s)\n",
sc->opath->provider->name, gp->name);
}
sc->opath = NULL;
} else {
cp1 = LIST_FIRST(&gp->consumer);
}
if (cp1 == NULL)
cp1 = LIST_FIRST(&gp->consumer);
printf("Open new path (%s) on fox (%s)\n",
cp1->provider->name, gp->name);
error = g_access_rel(cp1, sc->cr, sc->cw, sc->ce);
if (error) {
/*
* If we failed, we take another trip through here
*/
printf("Open new path (%s) on fox (%s) failed, reselect.\n",
cp1->provider->name, gp->name);
sc->opath = cp1;
g_post_event(g_fox_select_path, gp, M_WAITOK, gp, NULL);
} else {
printf("Open new path (%s) on fox (%s) succeeded\n",
cp1->provider->name, gp->name);
mtx_lock(&sc->lock);
sc->path = cp1;
sc->waiting = 0;
for (;;) {
bp = TAILQ_FIRST(&sc->queue);
if (bp == NULL)
break;
TAILQ_REMOVE(&sc->queue, bp, bio_queue);
g_io_request(bp, sc->path);
}
mtx_unlock(&sc->lock);
}
}
static void
g_fox_orphan(struct g_consumer *cp)
{
struct g_geom *gp;
struct g_fox_softc *sc;
int error, mark;
g_topology_assert();
gp = cp->geom;
sc = gp->softc;
printf("Removing path (%s) from fox (%s)\n",
cp->provider->name, gp->name);
mtx_lock(&sc->lock);
if (cp == sc->path) {
sc->opath = NULL;
sc->path = NULL;
sc->waiting = 1;
mark = 1;
} else {
mark = 0;
}
mtx_unlock(&sc->lock);
g_access_rel(cp, -cp->acr, -cp->acw, -cp->ace);
error = cp->provider->error;
g_detach(cp);
g_destroy_consumer(cp);
if (!LIST_EMPTY(&gp->consumer)) {
if (mark)
g_post_event(g_fox_select_path, gp, M_WAITOK, gp, NULL);
return;
}
mtx_destroy(&sc->lock);
g_free(gp->softc);
gp->softc = NULL;
g_wither_geom(gp, ENXIO);
}
static void
g_fox_done(struct bio *bp)
{
struct g_geom *gp;
struct g_fox_softc *sc;
int error;
if (bp->bio_error == 0) {
g_std_done(bp);
return;
}
gp = bp->bio_from->geom;
sc = gp->softc;
if (bp->bio_from != sc->path) {
g_io_request(bp, sc->path);
return;
}
mtx_lock(&sc->lock);
sc->opath = sc->path;
sc->path = NULL;
error = g_post_event(g_fox_select_path, gp, M_NOWAIT, gp, NULL);
if (error) {
bp->bio_error = ENOMEM;
g_std_done(bp);
} else {
sc->waiting = 1;
TAILQ_INSERT_TAIL(&sc->queue, bp, bio_queue);
}
mtx_unlock(&sc->lock);
}
static void
g_fox_start(struct bio *bp)
{
struct g_geom *gp;
struct bio *bp2;
struct g_fox_softc *sc;
int error;
gp = bp->bio_to->geom;
sc = gp->softc;
if (sc == NULL) {
g_io_deliver(bp, ENXIO);
return;
}
switch(bp->bio_cmd) {
case BIO_READ:
case BIO_WRITE:
case BIO_DELETE:
bp2 = g_clone_bio(bp);
if (bp2 == NULL) {
g_io_deliver(bp, ENOMEM);
break;
}
bp2->bio_offset += sc->sectorsize;
bp2->bio_done = g_fox_done;
mtx_lock(&sc->lock);
if (sc->path == NULL || !TAILQ_EMPTY(&sc->queue)) {
if (sc->waiting == 0) {
error = g_post_event(g_fox_select_path, gp,
M_NOWAIT, gp, NULL);
if (error) {
g_destroy_bio(bp2);
bp2 = NULL;
g_io_deliver(bp, error);
} else {
sc->waiting = 1;
}
}
if (bp2 != NULL)
TAILQ_INSERT_TAIL(&sc->queue, bp2,
bio_queue);
} else {
g_io_request(bp2, sc->path);
}
mtx_unlock(&sc->lock);
break;
default:
g_io_deliver(bp, EOPNOTSUPP);
break;
}
return;
}
static int
g_fox_access(struct g_provider *pp, int dr, int dw, int de)
{
struct g_geom *gp;
struct g_fox_softc *sc;
struct g_consumer *cp1;
int error;
g_topology_assert();
gp = pp->geom;
sc = gp->softc;
if (sc == NULL)
return (ENXIO);
if (sc->cr == 0 && sc->cw == 0 && sc->ce == 0) {
/*
* First open, open all consumers with an exclusive bit
*/
error = 0;
LIST_FOREACH(cp1, &gp->consumer, consumer) {
error = g_access_rel(cp1, 0, 0, 1);
if (error) {
printf("FOX: access(%s,0,0,1) = %d\n",
cp1->provider->name, error);
break;
}
}
if (error) {
LIST_FOREACH(cp1, &gp->consumer, consumer) {
if (cp1->ace)
g_access_rel(cp1, 0, 0, -1);
}
return (error);
}
}
if (sc->path == NULL)
g_fox_select_path(gp, 0);
if (sc->path == NULL)
error = ENXIO;
else
error = g_access_rel(sc->path, dr, dw, de);
if (error == 0) {
sc->cr += dr;
sc->cw += dw;
sc->ce += de;
if (sc->cr == 0 && sc->cw == 0 && sc->ce == 0) {
/*
* Last close, remove e-bit on all consumers
*/
LIST_FOREACH(cp1, &gp->consumer, consumer)
g_access_rel(cp1, 0, 0, -1);
}
}
return (error);
}
static struct g_geom *
g_fox_taste(struct g_class *mp, struct g_provider *pp, int flags __unused)
{
struct g_geom *gp, *gp2;
struct g_provider *pp2;
struct g_consumer *cp, *cp2;
struct g_fox_softc *sc, *sc2;
int error;
u_int sectorsize;
u_char *buf;
g_trace(G_T_TOPOLOGY, "fox_taste(%s, %s)", mp->name, pp->name);
g_topology_assert();
if (!strcmp(pp->geom->class->name, mp->name))
return (NULL);
gp = g_new_geomf(mp, "%s.fox", pp->name);
gp->softc = g_malloc(sizeof(struct g_fox_softc), M_WAITOK | M_ZERO);
sc = gp->softc;
gp->start = g_fox_start;
gp->spoiled = g_fox_orphan;
gp->orphan = g_fox_orphan;
gp->access= g_fox_access;
cp = g_new_consumer(gp);
g_attach(cp, pp);
error = g_access_rel(cp, 1, 0, 0);
if (error) {
g_free(sc);
g_detach(cp);
g_destroy_consumer(cp);
g_destroy_geom(gp);
return(NULL);
}
do {
sectorsize = cp->provider->sectorsize;
g_topology_unlock();
buf = g_read_data(cp, 0, sectorsize, &error);
g_topology_lock();
if (buf == NULL || error != 0)
break;
if (memcmp(buf, FOX_MAGIC, strlen(FOX_MAGIC)))
break;
/*
* First we need to see if this a new path for an existing fox.
*/
LIST_FOREACH(gp2, &mp->geom, geom) {
sc2 = gp2->softc;
if (sc2 == NULL)
continue;
if (memcmp(buf + 16, sc2->magic, sizeof sc2->magic))
continue;
break;
}
if (gp2 != NULL) {
/*
* It was. Create a new consumer for that fox,
* attach it, and if the fox is open, open this
* path with an exclusive count of one.
*/
printf("Adding path (%s) to fox (%s)\n",
pp->name, gp2->name);
cp2 = g_new_consumer(gp2);
g_attach(cp2, pp);
pp2 = LIST_FIRST(&gp2->provider);
if (pp2->acr > 0 || pp2->acw > 0 || pp2->ace > 0) {
error = g_access_rel(cp2, 0, 0, 1);
if (error) {
/*
* This is bad, or more likely,
* the user is doing something stupid
*/
printf(
"WARNING: New path (%s) to fox(%s) not added: %s\n%s",
cp2->provider->name, gp2->name,
"Could not get exclusive bit.",
"WARNING: This indicates a risk of data inconsistency."
);
g_detach(cp2);
g_destroy_consumer(cp2);
}
}
break;
}
printf("Creating new fox (%s)\n", pp->name);
sc->path = cp;
memcpy(sc->magic, buf + 16, sizeof sc->magic);
pp2 = g_new_providerf(gp, "%s", gp->name);
pp2->mediasize = sc->mediasize = pp->mediasize - pp->sectorsize;
pp2->sectorsize = sc->sectorsize = pp->sectorsize;
printf("fox %s lock %p\n", gp->name, &sc->lock);
mtx_init(&sc->lock, "fox queue", NULL, MTX_DEF);
TAILQ_INIT(&sc->queue);
g_error_provider(pp2, 0);
} while (0);
if (buf != NULL)
g_free(buf);
g_access_rel(cp, -1, 0, 0);
if (!LIST_EMPTY(&gp->provider))
return (gp);
g_free(gp->softc);
g_detach(cp);
g_destroy_consumer(cp);
g_destroy_geom(gp);
return (NULL);
}
static int
g_fox_destroy_geom(struct gctl_req *req, struct g_class *mp, struct g_geom *gp)
{
struct g_fox_softc *sc;
g_topology_assert();
sc = gp->softc;
gp->softc = NULL;
mtx_destroy(&sc->lock);
g_free(gp->softc);
g_wither_geom(gp, ENXIO);
return (0);
}
static struct g_class g_fox_class = {
.name = FOX_CLASS_NAME,
.taste = g_fox_taste,
.destroy_geom = g_fox_destroy_geom,
};
DECLARE_GEOM_CLASS(g_fox_class, g_fox);
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