freebsd-dev/sys/geom/bde/g_bde_work.c
Julian Elischer 3745c395ec Rename the kthread_xxx (e.g. kthread_create()) calls
to kproc_xxx as they actually make whole processes.
Thos makes way for us to add REAL kthread_create() and friends
that actually make theads. it turns out that most of these
calls actually end up being moved back to the thread version
when it's added. but we need to make this cosmetic change first.

I'd LOVE to do this rename in 7.0  so that we can eventually MFC the
new kthread_xxx() calls.
2007-10-20 23:23:23 +00:00

765 lines
20 KiB
C

/*-
* Copyright (c) 2002 Poul-Henning Kamp
* Copyright (c) 2002 Networks Associates Technology, Inc.
* All rights reserved.
*
* This software was developed for the FreeBSD Project by Poul-Henning Kamp
* and NAI Labs, the Security Research Division of Network Associates, Inc.
* under DARPA/SPAWAR contract N66001-01-C-8035 ("CBOSS"), as part of the
* DARPA CHATS research program.
*
* 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.
*
* 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.
*
* $FreeBSD$
*/
/*
* This source file contains the state-engine which makes things happen in the
* right order.
*
* Outline:
* 1) g_bde_start1()
* Break the struct bio into multiple work packets one per zone.
* 2) g_bde_start2()
* Setup the necessary sector buffers and start those read operations
* which we can start at this time and put the item on the work-list.
* 3) g_bde_worker()
* Scan the work-list for items which are ready for crypto processing
* and call the matching crypto function in g_bde_crypt.c and schedule
* any writes needed. Read operations finish here by releasing the
* sector buffers and delivering the original bio request.
* 4) g_bde_write_done()
* Release sector buffers and deliver the original bio request.
*
* Because of the C-scope rules, the functions are almost perfectly in the
* opposite order in this source file.
*
* XXX: A switch to the hardware assisted crypto in src/sys/opencrypto will add
* XXX: additional states to this state-engine. Since no hardware available
* XXX: at this time has AES support, implementing this has been postponed
* XXX: until such time as it would result in a benefit.
*/
#include <sys/param.h>
#include <sys/bio.h>
#include <sys/lock.h>
#include <sys/mutex.h>
#include <sys/queue.h>
#include <sys/malloc.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/sysctl.h>
#include <sys/proc.h>
#include <sys/kthread.h>
#include <crypto/rijndael/rijndael-api-fst.h>
#include <crypto/sha2/sha2.h>
#include <geom/geom.h>
#include <geom/bde/g_bde.h>
static void g_bde_delete_sector(struct g_bde_softc *wp, struct g_bde_sector *sp);
static struct g_bde_sector * g_bde_new_sector(struct g_bde_work *wp, u_int len);
static void g_bde_release_keysector(struct g_bde_work *wp);
static struct g_bde_sector *g_bde_get_keysector(struct g_bde_work *wp);
static int g_bde_start_read(struct g_bde_sector *sp);
static void g_bde_purge_sector(struct g_bde_softc *sc, int fraction);
/*
* Work item allocation.
*
* C++ would call these constructors and destructors.
*/
static u_int g_bde_nwork;
SYSCTL_UINT(_debug, OID_AUTO, gbde_nwork, CTLFLAG_RD, &g_bde_nwork, 0, "");
static MALLOC_DEFINE(M_GBDE, "gbde", "GBDE data structures");
static struct g_bde_work *
g_bde_new_work(struct g_bde_softc *sc)
{
struct g_bde_work *wp;
wp = malloc(sizeof *wp, M_GBDE, M_NOWAIT | M_ZERO);
if (wp == NULL)
return (wp);
wp->state = SETUP;
wp->softc = sc;
g_bde_nwork++;
sc->nwork++;
TAILQ_INSERT_TAIL(&sc->worklist, wp, list);
return (wp);
}
static void
g_bde_delete_work(struct g_bde_work *wp)
{
struct g_bde_softc *sc;
sc = wp->softc;
g_bde_nwork--;
sc->nwork--;
TAILQ_REMOVE(&sc->worklist, wp, list);
free(wp, M_GBDE);
}
/*
* Sector buffer allocation
*
* These two functions allocate and free back variable sized sector buffers
*/
static u_int g_bde_nsect;
SYSCTL_UINT(_debug, OID_AUTO, gbde_nsect, CTLFLAG_RD, &g_bde_nsect, 0, "");
static void
g_bde_delete_sector(struct g_bde_softc *sc, struct g_bde_sector *sp)
{
g_bde_nsect--;
sc->nsect--;
if (sp->malloc)
free(sp->data, M_GBDE);
free(sp, M_GBDE);
}
static struct g_bde_sector *
g_bde_new_sector(struct g_bde_work *wp, u_int len)
{
struct g_bde_sector *sp;
sp = malloc(sizeof *sp, M_GBDE, M_NOWAIT | M_ZERO);
if (sp == NULL)
return (sp);
if (len > 0) {
sp->data = malloc(len, M_GBDE, M_NOWAIT | M_ZERO);
if (sp->data == NULL) {
free(sp, M_GBDE);
return (NULL);
}
sp->malloc = 1;
}
g_bde_nsect++;
wp->softc->nsect++;
sp->size = len;
sp->softc = wp->softc;
sp->ref = 1;
sp->owner = wp;
sp->offset = wp->so;
sp->state = JUNK;
return (sp);
}
/*
* Skey sector cache.
*
* Nothing prevents two separate I/O requests from addressing the same zone
* and thereby needing the same skey sector. We therefore need to sequence
* I/O operations to the skey sectors. A certain amount of caching is also
* desirable, although the extent of benefit from this is not at this point
* determined.
*
* XXX: GEOM may be able to grow a generic caching facility at some point
* XXX: to support such needs.
*/
static u_int g_bde_ncache;
SYSCTL_UINT(_debug, OID_AUTO, gbde_ncache, CTLFLAG_RD, &g_bde_ncache, 0, "");
static void
g_bde_purge_one_sector(struct g_bde_softc *sc, struct g_bde_sector *sp)
{
g_trace(G_T_TOPOLOGY, "g_bde_purge_one_sector(%p, %p)", sc, sp);
if (sp->ref != 0)
return;
TAILQ_REMOVE(&sc->freelist, sp, list);
g_bde_ncache--;
sc->ncache--;
bzero(sp->data, sp->size);
g_bde_delete_sector(sc, sp);
}
static struct g_bde_sector *
g_bde_get_keysector(struct g_bde_work *wp)
{
struct g_bde_sector *sp;
struct g_bde_softc *sc;
off_t offset;
offset = wp->kso;
g_trace(G_T_TOPOLOGY, "g_bde_get_keysector(%p, %jd)", wp, (intmax_t)offset);
sc = wp->softc;
if (malloc_last_fail() < g_bde_ncache)
g_bde_purge_sector(sc, -1);
sp = TAILQ_FIRST(&sc->freelist);
if (sp != NULL && sp->ref == 0 && sp->used + 300 < time_uptime)
g_bde_purge_one_sector(sc, sp);
TAILQ_FOREACH(sp, &sc->freelist, list) {
if (sp->offset == offset)
break;
}
if (sp != NULL) {
sp->ref++;
KASSERT(sp->offset == offset, ("wrong offset"));
KASSERT(sp->softc == wp->softc, ("wrong softc"));
if (sp->ref == 1)
sp->owner = wp;
} else {
if (malloc_last_fail() < g_bde_ncache) {
TAILQ_FOREACH(sp, &sc->freelist, list)
if (sp->ref == 0)
break;
}
if (sp == NULL && !TAILQ_EMPTY(&sc->freelist))
sp = TAILQ_FIRST(&sc->freelist);
if (sp != NULL && sp->ref > 0)
sp = NULL;
if (sp == NULL) {
sp = g_bde_new_sector(wp, sc->sectorsize);
if (sp != NULL) {
g_bde_ncache++;
sc->ncache++;
TAILQ_INSERT_TAIL(&sc->freelist, sp, list);
sp->malloc = 2;
}
}
if (sp != NULL) {
sp->offset = offset;
sp->softc = wp->softc;
sp->ref = 1;
sp->owner = wp;
sp->state = JUNK;
sp->error = 0;
}
}
if (sp != NULL) {
TAILQ_REMOVE(&sc->freelist, sp, list);
TAILQ_INSERT_TAIL(&sc->freelist, sp, list);
sp->used = time_uptime;
}
wp->ksp = sp;
return(sp);
}
static void
g_bde_release_keysector(struct g_bde_work *wp)
{
struct g_bde_softc *sc;
struct g_bde_work *wp2;
struct g_bde_sector *sp;
sp = wp->ksp;
g_trace(G_T_TOPOLOGY, "g_bde_release_keysector(%p)", sp);
KASSERT(sp->malloc == 2, ("Wrong sector released"));
sc = sp->softc;
KASSERT(sc != NULL, ("NULL sp->softc"));
KASSERT(wp == sp->owner, ("Releasing, not owner"));
sp->owner = NULL;
wp->ksp = NULL;
sp->ref--;
if (sp->ref > 0) {
TAILQ_REMOVE(&sc->freelist, sp, list);
TAILQ_INSERT_TAIL(&sc->freelist, sp, list);
TAILQ_FOREACH(wp2, &sc->worklist, list) {
if (wp2->ksp == sp) {
KASSERT(wp2 != wp, ("Self-reowning"));
sp->owner = wp2;
wakeup(sp->softc);
break;
}
}
KASSERT(wp2 != NULL, ("Failed to pick up owner for %p\n", sp));
} else if (sp->error != 0) {
sp->offset = ~0;
sp->error = 0;
sp->state = JUNK;
}
TAILQ_REMOVE(&sc->freelist, sp, list);
TAILQ_INSERT_HEAD(&sc->freelist, sp, list);
}
static void
g_bde_purge_sector(struct g_bde_softc *sc, int fraction)
{
struct g_bde_sector *sp;
int n;
g_trace(G_T_TOPOLOGY, "g_bde_purge_sector(%p)", sc);
if (fraction > 0)
n = sc->ncache / fraction + 1;
else
n = g_bde_ncache - malloc_last_fail();
if (n < 0)
return;
if (n > sc->ncache)
n = sc->ncache;
while(n--) {
TAILQ_FOREACH(sp, &sc->freelist, list) {
if (sp->ref != 0)
continue;
TAILQ_REMOVE(&sc->freelist, sp, list);
g_bde_ncache--;
sc->ncache--;
bzero(sp->data, sp->size);
g_bde_delete_sector(sc, sp);
break;
}
}
}
static struct g_bde_sector *
g_bde_read_keysector(struct g_bde_softc *sc, struct g_bde_work *wp)
{
struct g_bde_sector *sp;
g_trace(G_T_TOPOLOGY, "g_bde_read_keysector(%p)", wp);
sp = g_bde_get_keysector(wp);
if (sp == NULL) {
g_bde_purge_sector(sc, -1);
sp = g_bde_get_keysector(wp);
}
if (sp == NULL)
return (sp);
if (sp->owner != wp)
return (sp);
if (sp->state == VALID)
return (sp);
if (g_bde_start_read(sp) == 0)
return (sp);
g_bde_release_keysector(wp);
return (NULL);
}
/*
* Contribute to the completion of the original bio request.
*
* We have no simple way to tell how many bits the original bio request has
* been segmented into, so the easiest way to determine when we can deliver
* it is to keep track of the number of bytes we have completed. We keep
* track of any errors underway and latch onto the first one.
*
* We always report "nothing done" in case of error, because random bits here
* and there may be completed and returning a number of completed bytes does
* not convey any useful information about which bytes they were. If some
* piece of broken code somewhere interprets this to mean that nothing has
* changed on the underlying media they deserve the lossage headed for them.
*
* A single mutex per g_bde instance is used to prevent contention.
*/
static void
g_bde_contribute(struct bio *bp, off_t bytes, int error)
{
g_trace(G_T_TOPOLOGY, "g_bde_contribute bp %p bytes %jd error %d",
bp, (intmax_t)bytes, error);
if (bp->bio_error == 0)
bp->bio_error = error;
bp->bio_completed += bytes;
KASSERT(bp->bio_completed <= bp->bio_length, ("Too large contribution"));
if (bp->bio_completed == bp->bio_length) {
if (bp->bio_error != 0)
bp->bio_completed = 0;
g_io_deliver(bp, bp->bio_error);
}
}
/*
* This is the common case "we're done with this work package" function
*/
static void
g_bde_work_done(struct g_bde_work *wp, int error)
{
g_bde_contribute(wp->bp, wp->length, error);
if (wp->sp != NULL)
g_bde_delete_sector(wp->softc, wp->sp);
if (wp->ksp != NULL)
g_bde_release_keysector(wp);
g_bde_delete_work(wp);
}
/*
* A write operation has finished. When we have all expected cows in the
* barn close the door and call it a day.
*/
static void
g_bde_write_done(struct bio *bp)
{
struct g_bde_sector *sp;
struct g_bde_work *wp;
struct g_bde_softc *sc;
sp = bp->bio_caller1;
sc = bp->bio_caller2;
mtx_lock(&sc->worklist_mutex);
KASSERT(sp != NULL, ("NULL sp"));
KASSERT(sc != NULL, ("NULL sc"));
KASSERT(sp->owner != NULL, ("NULL sp->owner"));
g_trace(G_T_TOPOLOGY, "g_bde_write_done(%p)", sp);
if (bp->bio_error == 0 && bp->bio_completed != sp->size)
bp->bio_error = EIO;
sp->error = bp->bio_error;
g_destroy_bio(bp);
wp = sp->owner;
if (wp->error == 0)
wp->error = sp->error;
if (wp->bp->bio_cmd == BIO_DELETE) {
KASSERT(sp == wp->sp, ("trashed delete op"));
g_bde_work_done(wp, wp->error);
mtx_unlock(&sc->worklist_mutex);
return;
}
KASSERT(wp->bp->bio_cmd == BIO_WRITE, ("Confused in g_bde_write_done()"));
KASSERT(sp == wp->sp || sp == wp->ksp, ("trashed write op"));
if (wp->sp == sp) {
g_bde_delete_sector(sc, wp->sp);
wp->sp = NULL;
} else {
sp->state = VALID;
}
if (wp->sp == NULL && wp->ksp != NULL && wp->ksp->state == VALID)
g_bde_work_done(wp, wp->error);
mtx_unlock(&sc->worklist_mutex);
return;
}
/*
* Send a write request for the given sector down the pipeline.
*/
static int
g_bde_start_write(struct g_bde_sector *sp)
{
struct bio *bp;
struct g_bde_softc *sc;
g_trace(G_T_TOPOLOGY, "g_bde_start_write(%p)", sp);
sc = sp->softc;
KASSERT(sc != NULL, ("NULL sc in g_bde_start_write"));
KASSERT(sp->owner != NULL, ("NULL sp->owner in g_bde_start_write"));
bp = g_new_bio();
if (bp == NULL)
return (ENOMEM);
bp->bio_cmd = BIO_WRITE;
bp->bio_offset = sp->offset;
bp->bio_data = sp->data;
bp->bio_length = sp->size;
bp->bio_done = g_bde_write_done;
bp->bio_caller1 = sp;
bp->bio_caller2 = sc;
sp->state = IO;
g_io_request(bp, sc->consumer);
return(0);
}
/*
* A read operation has finished. Mark the sector no longer iobusy and
* wake up the worker thread and let it do its thing.
*/
static void
g_bde_read_done(struct bio *bp)
{
struct g_bde_sector *sp;
struct g_bde_softc *sc;
sp = bp->bio_caller1;
g_trace(G_T_TOPOLOGY, "g_bde_read_done(%p)", sp);
sc = bp->bio_caller2;
mtx_lock(&sc->worklist_mutex);
if (bp->bio_error == 0 && bp->bio_completed != sp->size)
bp->bio_error = EIO;
sp->error = bp->bio_error;
if (sp->error == 0)
sp->state = VALID;
else
sp->state = JUNK;
wakeup(sc);
g_destroy_bio(bp);
mtx_unlock(&sc->worklist_mutex);
}
/*
* Send a read request for the given sector down the pipeline.
*/
static int
g_bde_start_read(struct g_bde_sector *sp)
{
struct bio *bp;
struct g_bde_softc *sc;
g_trace(G_T_TOPOLOGY, "g_bde_start_read(%p)", sp);
sc = sp->softc;
KASSERT(sc != NULL, ("Null softc in sp %p", sp));
bp = g_new_bio();
if (bp == NULL)
return (ENOMEM);
bp->bio_cmd = BIO_READ;
bp->bio_offset = sp->offset;
bp->bio_data = sp->data;
bp->bio_length = sp->size;
bp->bio_done = g_bde_read_done;
bp->bio_caller1 = sp;
bp->bio_caller2 = sc;
sp->state = IO;
g_io_request(bp, sc->consumer);
return(0);
}
/*
* The worker thread.
*
* The up/down path of GEOM is not allowed to sleep or do any major work
* so we use this thread to do the actual crypto operations and to push
* the state engine onwards.
*
* XXX: if we switch to the src/sys/opencrypt hardware assisted encryption
* XXX: using a thread here is probably not needed.
*/
void
g_bde_worker(void *arg)
{
struct g_bde_softc *sc;
struct g_bde_work *wp, *twp;
struct g_geom *gp;
int restart, error;
gp = arg;
sc = gp->softc;
mtx_lock(&sc->worklist_mutex);
for (;;) {
restart = 0;
g_trace(G_T_TOPOLOGY, "g_bde_worker scan");
TAILQ_FOREACH_SAFE(wp, &sc->worklist, list, twp) {
KASSERT(wp != NULL, ("NULL wp"));
KASSERT(wp->softc != NULL, ("NULL wp->softc"));
if (wp->state != WAIT)
continue; /* Not interesting here */
KASSERT(wp->bp != NULL, ("NULL wp->bp"));
KASSERT(wp->sp != NULL, ("NULL wp->sp"));
if (wp->ksp != NULL) {
if (wp->ksp->owner != wp)
continue;
if (wp->ksp->state == IO)
continue;
KASSERT(wp->ksp->state == VALID,
("Illegal sector state (%d)",
wp->ksp->state));
}
if (wp->bp->bio_cmd == BIO_READ && wp->sp->state == IO)
continue;
if (wp->ksp != NULL && wp->ksp->error != 0) {
g_bde_work_done(wp, wp->ksp->error);
continue;
}
switch(wp->bp->bio_cmd) {
case BIO_READ:
if (wp->ksp == NULL) {
KASSERT(wp->error != 0,
("BIO_READ, no ksp and no error"));
g_bde_work_done(wp, wp->error);
break;
}
if (wp->sp->error != 0) {
g_bde_work_done(wp, wp->sp->error);
break;
}
mtx_unlock(&sc->worklist_mutex);
g_bde_crypt_read(wp);
mtx_lock(&sc->worklist_mutex);
restart++;
g_bde_work_done(wp, wp->sp->error);
break;
case BIO_WRITE:
wp->state = FINISH;
KASSERT(wp->sp->owner == wp,
("Write not owner sp"));
KASSERT(wp->ksp->owner == wp,
("Write not owner ksp"));
mtx_unlock(&sc->worklist_mutex);
g_bde_crypt_write(wp);
mtx_lock(&sc->worklist_mutex);
restart++;
error = g_bde_start_write(wp->sp);
if (error) {
g_bde_work_done(wp, error);
break;
}
error = g_bde_start_write(wp->ksp);
if (wp->error != 0)
wp->error = error;
break;
case BIO_DELETE:
wp->state = FINISH;
mtx_unlock(&sc->worklist_mutex);
g_bde_crypt_delete(wp);
mtx_lock(&sc->worklist_mutex);
restart++;
g_bde_start_write(wp->sp);
break;
}
if (restart)
break;
}
if (!restart) {
/*
* We don't look for our death-warrant until we are
* idle. Shouldn't make a difference in practice.
*/
if (sc->dead)
break;
g_trace(G_T_TOPOLOGY, "g_bde_worker sleep");
error = msleep(sc, &sc->worklist_mutex,
PRIBIO, "-", hz);
if (error == EWOULDBLOCK) {
/*
* Lose our skey cache in an orderly fashion.
* The exact rate can be tuned to be less
* aggressive if this is desirable. 10% per
* second means that the cache is gone in a
* few minutes.
*/
g_bde_purge_sector(sc, 10);
}
}
}
g_trace(G_T_TOPOLOGY, "g_bde_worker die");
g_bde_purge_sector(sc, 1);
KASSERT(sc->nwork == 0, ("Dead but %d work remaining", sc->nwork));
KASSERT(sc->ncache == 0, ("Dead but %d cache remaining", sc->ncache));
KASSERT(sc->nsect == 0, ("Dead but %d sect remaining", sc->nsect));
mtx_unlock(&sc->worklist_mutex);
sc->dead = 2;
wakeup(sc);
kproc_exit(0);
}
/*
* g_bde_start1 has chopped the incoming request up so all the requests
* we see here are inside a single zone. Map the data and key locations
* grab the buffers we need and fire off the first volley of read requests.
*/
static void
g_bde_start2(struct g_bde_work *wp)
{
struct g_bde_softc *sc;
KASSERT(wp != NULL, ("NULL wp in g_bde_start2"));
KASSERT(wp->softc != NULL, ("NULL wp->softc"));
g_trace(G_T_TOPOLOGY, "g_bde_start2(%p)", wp);
sc = wp->softc;
switch (wp->bp->bio_cmd) {
case BIO_READ:
wp->sp = g_bde_new_sector(wp, 0);
if (wp->sp == NULL) {
g_bde_work_done(wp, ENOMEM);
return;
}
wp->sp->size = wp->length;
wp->sp->data = wp->data;
if (g_bde_start_read(wp->sp) != 0) {
g_bde_work_done(wp, ENOMEM);
return;
}
g_bde_read_keysector(sc, wp);
if (wp->ksp == NULL)
wp->error = ENOMEM;
break;
case BIO_DELETE:
wp->sp = g_bde_new_sector(wp, wp->length);
if (wp->sp == NULL) {
g_bde_work_done(wp, ENOMEM);
return;
}
break;
case BIO_WRITE:
wp->sp = g_bde_new_sector(wp, wp->length);
if (wp->sp == NULL) {
g_bde_work_done(wp, ENOMEM);
return;
}
g_bde_read_keysector(sc, wp);
if (wp->ksp == NULL) {
g_bde_work_done(wp, ENOMEM);
return;
}
break;
default:
KASSERT(0 == 1,
("Wrong bio_cmd %d in g_bde_start2", wp->bp->bio_cmd));
}
wp->state = WAIT;
wakeup(sc);
}
/*
* Create a sequence of work structures, and have g_bde_map_sector() determine
* how long they each can be. Feed them to g_bde_start2().
*/
void
g_bde_start1(struct bio *bp)
{
struct g_bde_softc *sc;
struct g_bde_work *wp;
off_t done;
sc = bp->bio_to->geom->softc;
bp->bio_driver1 = sc;
mtx_lock(&sc->worklist_mutex);
for(done = 0; done < bp->bio_length; ) {
wp = g_bde_new_work(sc);
if (wp != NULL) {
wp->bp = bp;
wp->offset = bp->bio_offset + done;
wp->data = bp->bio_data + done;
wp->length = bp->bio_length - done;
g_bde_map_sector(wp);
done += wp->length;
g_bde_start2(wp);
}
if (wp == NULL || bp->bio_error != 0) {
g_bde_contribute(bp, bp->bio_length - done, ENOMEM);
break;
}
}
mtx_unlock(&sc->worklist_mutex);
return;
}