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NetBSD/sys/dev/fss.c

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/* $NetBSD: fss.c,v 1.34 2007/07/29 12:50:18 ad Exp $ */
/*-
* Copyright (c) 2003 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This code is derived from software contributed to The NetBSD Foundation
* by Juergen Hannken-Illjes.
*
* 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. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the NetBSD
* Foundation, Inc. and its contributors.
* 4. Neither the name of The NetBSD Foundation nor the names of its
* contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. 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 FOUNDATION 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.
*/
/*
* File system snapshot disk driver.
*
* Block/character interface to the snapshot of a mounted file system.
*/
#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: fss.c,v 1.34 2007/07/29 12:50:18 ad Exp $");
#include "fss.h"
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/namei.h>
#include <sys/proc.h>
#include <sys/errno.h>
#include <sys/buf.h>
#include <sys/malloc.h>
#include <sys/ioctl.h>
#include <sys/disklabel.h>
#include <sys/device.h>
#include <sys/disk.h>
#include <sys/stat.h>
#include <sys/mount.h>
#include <sys/vnode.h>
#include <sys/file.h>
#include <sys/uio.h>
#include <sys/conf.h>
#include <sys/kthread.h>
#include <sys/fstrans.h>
#include <miscfs/specfs/specdev.h>
#include <dev/fssvar.h>
#include <machine/stdarg.h>
#ifdef DEBUG
#define FSS_STATISTICS
#endif
#ifdef FSS_STATISTICS
struct fss_stat {
u_int64_t cow_calls;
u_int64_t cow_copied;
u_int64_t cow_cache_full;
u_int64_t indir_read;
u_int64_t indir_write;
};
static struct fss_stat fss_stat[NFSS];
#define FSS_STAT_INC(sc, field) \
do { \
fss_stat[sc->sc_unit].field++; \
} while (0)
#define FSS_STAT_SET(sc, field, value) \
do { \
fss_stat[sc->sc_unit].field = value; \
} while (0)
#define FSS_STAT_ADD(sc, field, value) \
do { \
fss_stat[sc->sc_unit].field += value; \
} while (0)
#define FSS_STAT_VAL(sc, field) fss_stat[sc->sc_unit].field
#define FSS_STAT_CLEAR(sc) \
do { \
memset(&fss_stat[sc->sc_unit], 0, \
sizeof(struct fss_stat)); \
} while (0)
#else /* FSS_STATISTICS */
#define FSS_STAT_INC(sc, field)
#define FSS_STAT_SET(sc, field, value)
#define FSS_STAT_ADD(sc, field, value)
#define FSS_STAT_CLEAR(sc)
#endif /* FSS_STATISTICS */
static struct fss_softc fss_softc[NFSS];
void fssattach(int);
dev_type_open(fss_open);
dev_type_close(fss_close);
dev_type_read(fss_read);
dev_type_write(fss_write);
dev_type_ioctl(fss_ioctl);
dev_type_strategy(fss_strategy);
dev_type_dump(fss_dump);
dev_type_size(fss_size);
static int fss_copy_on_write(void *, struct buf *);
static inline void fss_error(struct fss_softc *, const char *, ...);
static int fss_create_files(struct fss_softc *, struct fss_set *,
off_t *, struct lwp *);
static int fss_create_snapshot(struct fss_softc *, struct fss_set *,
struct lwp *);
static int fss_delete_snapshot(struct fss_softc *, struct lwp *);
static int fss_softc_alloc(struct fss_softc *);
static void fss_softc_free(struct fss_softc *);
static void fss_cluster_iodone(struct buf *);
static void fss_read_cluster(struct fss_softc *, u_int32_t);
static void fss_bs_thread(void *);
static int fss_bs_io(struct fss_softc *, fss_io_type,
u_int32_t, off_t, int, void *);
static u_int32_t *fss_bs_indir(struct fss_softc *, u_int32_t);
const struct bdevsw fss_bdevsw = {
fss_open, fss_close, fss_strategy, fss_ioctl,
fss_dump, fss_size, D_DISK
};
const struct cdevsw fss_cdevsw = {
fss_open, fss_close, fss_read, fss_write, fss_ioctl,
nostop, notty, nopoll, nommap, nokqfilter, D_DISK
};
void
fssattach(int num)
{
int i;
struct fss_softc *sc;
for (i = 0; i < NFSS; i++) {
sc = &fss_softc[i];
sc->sc_unit = i;
sc->sc_bdev = NODEV;
simple_lock_init(&sc->sc_slock);
mutex_init(&sc->sc_lock, MUTEX_DRIVER, IPL_NONE);
bufq_alloc(&sc->sc_bufq, "fcfs", 0);
}
}
int
fss_open(dev_t dev, int flags, int mode, struct lwp *l)
{
int s, mflag;
struct fss_softc *sc;
mflag = (mode == S_IFCHR ? FSS_CDEV_OPEN : FSS_BDEV_OPEN);
if ((sc = FSS_DEV_TO_SOFTC(dev)) == NULL)
return ENODEV;
FSS_LOCK(sc, s);
sc->sc_flags |= mflag;
FSS_UNLOCK(sc, s);
return 0;
}
int
fss_close(dev_t dev, int flags, int mode, struct lwp *l)
{
int s, mflag, error;
struct fss_softc *sc;
mflag = (mode == S_IFCHR ? FSS_CDEV_OPEN : FSS_BDEV_OPEN);
if ((sc = FSS_DEV_TO_SOFTC(dev)) == NULL)
return ENODEV;
FSS_LOCK(sc, s);
if ((sc->sc_flags & (FSS_CDEV_OPEN|FSS_BDEV_OPEN)) == mflag) {
if ((sc->sc_uflags & FSS_UNCONFIG_ON_CLOSE) != 0 &&
(sc->sc_flags & FSS_ACTIVE) != 0) {
FSS_UNLOCK(sc, s);
error = fss_ioctl(dev, FSSIOCCLR, NULL, FWRITE, l);
if (error)
return error;
FSS_LOCK(sc, s);
}
sc->sc_uflags &= ~FSS_UNCONFIG_ON_CLOSE;
}
sc->sc_flags &= ~mflag;
FSS_UNLOCK(sc, s);
return 0;
}
void
fss_strategy(struct buf *bp)
{
int s;
struct fss_softc *sc;
sc = FSS_DEV_TO_SOFTC(bp->b_dev);
FSS_LOCK(sc, s);
if ((bp->b_flags & B_READ) != B_READ ||
sc == NULL || !FSS_ISVALID(sc)) {
FSS_UNLOCK(sc, s);
bp->b_error = (sc == NULL ? ENODEV : EROFS);
bp->b_resid = bp->b_bcount;
biodone(bp);
return;
}
bp->b_rawblkno = bp->b_blkno;
BUFQ_PUT(sc->sc_bufq, bp);
wakeup(&sc->sc_bs_lwp);
FSS_UNLOCK(sc, s);
}
int
fss_read(dev_t dev, struct uio *uio, int flags)
{
return physio(fss_strategy, NULL, dev, B_READ, minphys, uio);
}
int
fss_write(dev_t dev, struct uio *uio, int flags)
{
return physio(fss_strategy, NULL, dev, B_WRITE, minphys, uio);
}
int
fss_ioctl(dev_t dev, u_long cmd, void *data, int flag, struct lwp *l)
{
int error;
struct fss_softc *sc;
struct fss_set *fss = (struct fss_set *)data;
struct fss_get *fsg = (struct fss_get *)data;
if ((sc = FSS_DEV_TO_SOFTC(dev)) == NULL)
return ENODEV;
switch (cmd) {
case FSSIOCSET:
mutex_enter(&sc->sc_lock);
if ((flag & FWRITE) == 0)
error = EPERM;
else if ((sc->sc_flags & FSS_ACTIVE) != 0)
error = EBUSY;
else
error = fss_create_snapshot(sc, fss, l);
mutex_exit(&sc->sc_lock);
break;
case FSSIOCCLR:
mutex_enter(&sc->sc_lock);
if ((flag & FWRITE) == 0)
error = EPERM;
else if ((sc->sc_flags & FSS_ACTIVE) == 0)
error = ENXIO;
else
error = fss_delete_snapshot(sc, l);
mutex_exit(&sc->sc_lock);
break;
case FSSIOCGET:
mutex_enter(&sc->sc_lock);
switch (sc->sc_flags & (FSS_PERSISTENT | FSS_ACTIVE)) {
case FSS_ACTIVE:
memcpy(fsg->fsg_mount, sc->sc_mntname, MNAMELEN);
fsg->fsg_csize = FSS_CLSIZE(sc);
fsg->fsg_time = sc->sc_time;
fsg->fsg_mount_size = sc->sc_clcount;
fsg->fsg_bs_size = sc->sc_clnext;
error = 0;
break;
case FSS_PERSISTENT | FSS_ACTIVE:
memcpy(fsg->fsg_mount, sc->sc_mntname, MNAMELEN);
fsg->fsg_csize = 0;
fsg->fsg_time = sc->sc_time;
fsg->fsg_mount_size = 0;
fsg->fsg_bs_size = 0;
error = 0;
break;
default:
error = ENXIO;
break;
}
mutex_exit(&sc->sc_lock);
break;
case FSSIOFSET:
sc->sc_uflags = *(int *)data;
error = 0;
break;
case FSSIOFGET:
*(int *)data = sc->sc_uflags;
error = 0;
break;
default:
error = EINVAL;
break;
}
return error;
}
int
fss_size(dev_t dev)
{
return -1;
}
int
fss_dump(dev_t dev, daddr_t blkno, void *va,
size_t size)
{
return EROFS;
}
/*
* An error occurred reading or writing the snapshot or backing store.
* If it is the first error log to console.
* The caller holds the simplelock.
*/
static inline void
fss_error(struct fss_softc *sc, const char *fmt, ...)
{
va_list ap;
if ((sc->sc_flags & (FSS_ACTIVE|FSS_ERROR)) == FSS_ACTIVE) {
va_start(ap, fmt);
printf("fss%d: snapshot invalid: ", sc->sc_unit);
vprintf(fmt, ap);
printf("\n");
va_end(ap);
}
if ((sc->sc_flags & FSS_ACTIVE) == FSS_ACTIVE)
sc->sc_flags |= FSS_ERROR;
}
/*
* Allocate the variable sized parts of the softc and
* fork the kernel thread.
*
* The fields sc_clcount, sc_clshift, sc_cache_size and sc_indir_size
* must be initialized.
*/
static int
fss_softc_alloc(struct fss_softc *sc)
{
int i, len, error;
len = (sc->sc_clcount+NBBY-1)/NBBY;
sc->sc_copied = malloc(len, M_TEMP, M_ZERO|M_WAITOK|M_CANFAIL);
if (sc->sc_copied == NULL)
return(ENOMEM);
len = sc->sc_cache_size*sizeof(struct fss_cache);
sc->sc_cache = malloc(len, M_TEMP, M_ZERO|M_WAITOK|M_CANFAIL);
if (sc->sc_cache == NULL)
return(ENOMEM);
len = FSS_CLSIZE(sc);
for (i = 0; i < sc->sc_cache_size; i++) {
sc->sc_cache[i].fc_type = FSS_CACHE_FREE;
sc->sc_cache[i].fc_softc = sc;
sc->sc_cache[i].fc_xfercount = 0;
sc->sc_cache[i].fc_data = malloc(len, M_TEMP,
M_WAITOK|M_CANFAIL);
if (sc->sc_cache[i].fc_data == NULL)
return(ENOMEM);
}
len = (sc->sc_indir_size+NBBY-1)/NBBY;
sc->sc_indir_valid = malloc(len, M_TEMP, M_ZERO|M_WAITOK|M_CANFAIL);
if (sc->sc_indir_valid == NULL)
return(ENOMEM);
len = FSS_CLSIZE(sc);
sc->sc_indir_data = malloc(len, M_TEMP, M_ZERO|M_WAITOK|M_CANFAIL);
if (sc->sc_indir_data == NULL)
return(ENOMEM);
if ((error = kthread_create(PINOD, 0, NULL, fss_bs_thread, sc,
&sc->sc_bs_lwp, "fssbs%d", sc->sc_unit)) != 0)
return error;
sc->sc_flags |= FSS_BS_THREAD;
return 0;
}
/*
* Free the variable sized parts of the softc.
*/
static void
fss_softc_free(struct fss_softc *sc)
{
int s, i;
if ((sc->sc_flags & FSS_BS_THREAD) != 0) {
FSS_LOCK(sc, s);
sc->sc_flags &= ~FSS_BS_THREAD;
wakeup(&sc->sc_bs_lwp);
while (sc->sc_bs_lwp != NULL)
ltsleep(&sc->sc_bs_lwp, PRIBIO, "fssthread", 0,
&sc->sc_slock);
FSS_UNLOCK(sc, s);
}
if (sc->sc_copied != NULL)
free(sc->sc_copied, M_TEMP);
sc->sc_copied = NULL;
if (sc->sc_cache != NULL) {
for (i = 0; i < sc->sc_cache_size; i++)
if (sc->sc_cache[i].fc_data != NULL)
free(sc->sc_cache[i].fc_data, M_TEMP);
free(sc->sc_cache, M_TEMP);
}
sc->sc_cache = NULL;
if (sc->sc_indir_valid != NULL)
free(sc->sc_indir_valid, M_TEMP);
sc->sc_indir_valid = NULL;
if (sc->sc_indir_data != NULL)
free(sc->sc_indir_data, M_TEMP);
sc->sc_indir_data = NULL;
}
/*
* Check if an unmount is ok. If forced, set this snapshot into ERROR state.
*/
int
fss_umount_hook(struct mount *mp, int forced)
{
int i, s;
for (i = 0; i < NFSS; i++) {
FSS_LOCK(&fss_softc[i], s);
if ((fss_softc[i].sc_flags & FSS_ACTIVE) != 0 &&
fss_softc[i].sc_mount == mp) {
if (forced)
fss_error(&fss_softc[i], "forced unmount");
else {
FSS_UNLOCK(&fss_softc[i], s);
return EBUSY;
}
}
FSS_UNLOCK(&fss_softc[i], s);
}
return 0;
}
/*
* A buffer is written to the snapshotted block device. Copy to
* backing store if needed.
*/
static int
fss_copy_on_write(void *v, struct buf *bp)
{
int s;
u_int32_t cl, ch, c;
struct fss_softc *sc = v;
FSS_LOCK(sc, s);
if (!FSS_ISVALID(sc)) {
FSS_UNLOCK(sc, s);
return 0;
}
FSS_UNLOCK(sc, s);
FSS_STAT_INC(sc, cow_calls);
cl = FSS_BTOCL(sc, dbtob(bp->b_blkno));
ch = FSS_BTOCL(sc, dbtob(bp->b_blkno)+bp->b_bcount-1);
for (c = cl; c <= ch; c++)
fss_read_cluster(sc, c);
return 0;
}
/*
* Lookup and open needed files.
*
* For file system internal snapshot initializes sc_mntname, sc_mount,
* sc_bs_vp and sc_time.
*
* Otherwise returns dev and size of the underlying block device.
* Initializes sc_mntname, sc_mount_vp, sc_bdev, sc_bs_vp and sc_mount
*/
static int
fss_create_files(struct fss_softc *sc, struct fss_set *fss,
off_t *bsize, struct lwp *l)
{
int error, bits, fsbsize;
struct timespec ts;
struct partinfo dpart;
struct vattr va;
struct nameidata nd;
/*
* Get the mounted file system.
*/
NDINIT(&nd, LOOKUP, FOLLOW, UIO_USERSPACE, fss->fss_mount, l);
if ((error = namei(&nd)) != 0)
return error;
if ((nd.ni_vp->v_flag & VROOT) != VROOT) {
vrele(nd.ni_vp);
return EINVAL;
}
sc->sc_mount = nd.ni_vp->v_mount;
memcpy(sc->sc_mntname, sc->sc_mount->mnt_stat.f_mntonname, MNAMELEN);
vrele(nd.ni_vp);
/*
* Check for file system internal snapshot.
*/
NDINIT(&nd, LOOKUP, FOLLOW, UIO_USERSPACE, fss->fss_bstore, l);
if ((error = namei(&nd)) != 0)
return error;
if (nd.ni_vp->v_type == VREG && nd.ni_vp->v_mount == sc->sc_mount) {
vrele(nd.ni_vp);
sc->sc_flags |= FSS_PERSISTENT;
NDINIT(&nd, LOOKUP, FOLLOW, UIO_USERSPACE, fss->fss_bstore, l);
if ((error = vn_open(&nd, FREAD, 0)) != 0)
return error;
sc->sc_bs_vp = nd.ni_vp;
fsbsize = sc->sc_bs_vp->v_mount->mnt_stat.f_iosize;
bits = sizeof(sc->sc_bs_bshift)*NBBY;
for (sc->sc_bs_bshift = 1; sc->sc_bs_bshift < bits;
sc->sc_bs_bshift++)
if (FSS_FSBSIZE(sc) == fsbsize)
break;
if (sc->sc_bs_bshift >= bits) {
VOP_UNLOCK(sc->sc_bs_vp, 0);
return EINVAL;
}
sc->sc_bs_bmask = FSS_FSBSIZE(sc)-1;
sc->sc_clshift = 0;
error = VFS_SNAPSHOT(sc->sc_mount, sc->sc_bs_vp, &ts);
TIMESPEC_TO_TIMEVAL(&sc->sc_time, &ts);
VOP_UNLOCK(sc->sc_bs_vp, 0);
return error;
}
vrele(nd.ni_vp);
/*
* Get the block device it is mounted on.
*/
NDINIT(&nd, LOOKUP, FOLLOW, UIO_SYSSPACE,
sc->sc_mount->mnt_stat.f_mntfromname, l);
if ((error = namei(&nd)) != 0)
return error;
if (nd.ni_vp->v_type != VBLK) {
vrele(nd.ni_vp);
return EINVAL;
}
error = VOP_IOCTL(nd.ni_vp, DIOCGPART, &dpart, FREAD,
l->l_cred, l);
if (error) {
vrele(nd.ni_vp);
return error;
}
sc->sc_mount_vp = nd.ni_vp;
sc->sc_bdev = nd.ni_vp->v_rdev;
*bsize = (off_t)dpart.disklab->d_secsize*dpart.part->p_size;
vrele(nd.ni_vp);
/*
* Get the backing store
*/
NDINIT(&nd, LOOKUP, FOLLOW, UIO_USERSPACE, fss->fss_bstore, l);
if ((error = vn_open(&nd, FREAD|FWRITE, 0)) != 0)
return error;
VOP_UNLOCK(nd.ni_vp, 0);
sc->sc_bs_vp = nd.ni_vp;
if (nd.ni_vp->v_type != VREG && nd.ni_vp->v_type != VCHR)
return EINVAL;
if (sc->sc_bs_vp->v_type == VREG) {
error = VOP_GETATTR(sc->sc_bs_vp, &va, l->l_cred, l);
if (error != 0)
return error;
sc->sc_bs_size = va.va_size;
fsbsize = sc->sc_bs_vp->v_mount->mnt_stat.f_iosize;
if (fsbsize & (fsbsize-1)) /* No power of two */
return EINVAL;
for (sc->sc_bs_bshift = 1; sc->sc_bs_bshift < 32;
sc->sc_bs_bshift++)
if (FSS_FSBSIZE(sc) == fsbsize)
break;
if (sc->sc_bs_bshift >= 32)
return EINVAL;
sc->sc_bs_bmask = FSS_FSBSIZE(sc)-1;
} else {
sc->sc_bs_bshift = DEV_BSHIFT;
sc->sc_bs_bmask = FSS_FSBSIZE(sc)-1;
}
/*
* As all IO to from/to the backing store goes through
* VOP_STRATEGY() clean the buffer cache to prevent
* cache incoherencies.
*/
if ((error = vinvalbuf(sc->sc_bs_vp, V_SAVE, l->l_cred, l, 0, 0)) != 0)
return error;
return 0;
}
/*
* Create a snapshot.
*/
static int
fss_create_snapshot(struct fss_softc *sc, struct fss_set *fss, struct lwp *l)
{
int len, error;
u_int32_t csize;
off_t bsize;
bsize = 0; /* XXX gcc */
/*
* Open needed files.
*/
if ((error = fss_create_files(sc, fss, &bsize, l)) != 0)
goto bad;
if (sc->sc_flags & FSS_PERSISTENT) {
fss_softc_alloc(sc);
sc->sc_flags |= FSS_ACTIVE;
return 0;
}
/*
* Set cluster size. Must be a power of two and
* a multiple of backing store block size.
*/
if (fss->fss_csize <= 0)
csize = MAXPHYS;
else
csize = fss->fss_csize;
if (bsize/csize > FSS_CLUSTER_MAX)
csize = bsize/FSS_CLUSTER_MAX+1;
for (sc->sc_clshift = sc->sc_bs_bshift; sc->sc_clshift < 32;
sc->sc_clshift++)
if (FSS_CLSIZE(sc) >= csize)
break;
if (sc->sc_clshift >= 32) {
error = EINVAL;
goto bad;
}
sc->sc_clmask = FSS_CLSIZE(sc)-1;
/*
* Set number of cache slots.
*/
if (FSS_CLSIZE(sc) <= 8192)
sc->sc_cache_size = 32;
else if (FSS_CLSIZE(sc) <= 65536)
sc->sc_cache_size = 8;
else
sc->sc_cache_size = 4;
/*
* Set number of clusters and size of last cluster.
*/
sc->sc_clcount = FSS_BTOCL(sc, bsize-1)+1;
sc->sc_clresid = FSS_CLOFF(sc, bsize-1)+1;
/*
* Set size of indirect table.
*/
len = sc->sc_clcount*sizeof(u_int32_t);
sc->sc_indir_size = FSS_BTOCL(sc, len)+1;
sc->sc_clnext = sc->sc_indir_size;
sc->sc_indir_cur = 0;
if ((error = fss_softc_alloc(sc)) != 0)
goto bad;
/*
* Activate the snapshot.
*/
if ((error = vfs_suspend(sc->sc_mount, 0)) != 0)
goto bad;
microtime(&sc->sc_time);
if (error == 0)
error = vn_cow_establish(sc->sc_mount_vp,
fss_copy_on_write, sc);
if (error == 0)
sc->sc_flags |= FSS_ACTIVE;
vfs_resume(sc->sc_mount);
if (error != 0)
goto bad;
#ifdef DEBUG
printf("fss%d: %s snapshot active\n", sc->sc_unit, sc->sc_mntname);
printf("fss%d: %u clusters of %u, %u cache slots, %u indir clusters\n",
sc->sc_unit, sc->sc_clcount, FSS_CLSIZE(sc),
sc->sc_cache_size, sc->sc_indir_size);
#endif
return 0;
bad:
fss_softc_free(sc);
if (sc->sc_bs_vp != NULL) {
if (sc->sc_flags & FSS_PERSISTENT)
vn_close(sc->sc_bs_vp, FREAD, l->l_cred, l);
else
vn_close(sc->sc_bs_vp, FREAD|FWRITE, l->l_cred, l);
}
sc->sc_bs_vp = NULL;
return error;
}
/*
* Delete a snapshot.
*/
static int
fss_delete_snapshot(struct fss_softc *sc, struct lwp *l)
{
int s;
if ((sc->sc_flags & FSS_PERSISTENT) == 0)
vn_cow_disestablish(sc->sc_mount_vp, fss_copy_on_write, sc);
FSS_LOCK(sc, s);
sc->sc_flags &= ~(FSS_ACTIVE|FSS_ERROR);
sc->sc_mount = NULL;
sc->sc_bdev = NODEV;
FSS_UNLOCK(sc, s);
fss_softc_free(sc);
if (sc->sc_flags & FSS_PERSISTENT)
vn_close(sc->sc_bs_vp, FREAD, l->l_cred, l);
else
vn_close(sc->sc_bs_vp, FREAD|FWRITE, l->l_cred, l);
sc->sc_bs_vp = NULL;
sc->sc_flags &= ~FSS_PERSISTENT;
FSS_STAT_CLEAR(sc);
return 0;
}
/*
* A read from the snapshotted block device has completed.
*/
static void
fss_cluster_iodone(struct buf *bp)
{
int s;
struct fss_cache *scp = bp->b_private;
KASSERT(bp->b_vp == NULL);
FSS_LOCK(scp->fc_softc, s);
if (bp->b_error != 0)
fss_error(scp->fc_softc, "fs read error %d", bp->b_error);
if (--scp->fc_xfercount == 0)
wakeup(&scp->fc_data);
FSS_UNLOCK(scp->fc_softc, s);
putiobuf(bp);
}
/*
* Read a cluster from the snapshotted block device to the cache.
*/
static void
fss_read_cluster(struct fss_softc *sc, u_int32_t cl)
{
int s, todo, len;
char *addr;
daddr_t dblk;
struct buf *bp;
struct fss_cache *scp, *scl;
/*
* Get a free cache slot.
*/
scl = sc->sc_cache+sc->sc_cache_size;
FSS_LOCK(sc, s);
restart:
if (isset(sc->sc_copied, cl) || !FSS_ISVALID(sc)) {
FSS_UNLOCK(sc, s);
return;
}
for (scp = sc->sc_cache; scp < scl; scp++)
if (scp->fc_type != FSS_CACHE_FREE &&
scp->fc_cluster == cl) {
ltsleep(&scp->fc_type, PRIBIO, "cowwait2", 0,
&sc->sc_slock);
goto restart;
}
for (scp = sc->sc_cache; scp < scl; scp++)
if (scp->fc_type == FSS_CACHE_FREE) {
scp->fc_type = FSS_CACHE_BUSY;
scp->fc_cluster = cl;
break;
}
if (scp >= scl) {
FSS_STAT_INC(sc, cow_cache_full);
ltsleep(&sc->sc_cache, PRIBIO, "cowwait3", 0, &sc->sc_slock);
goto restart;
}
FSS_UNLOCK(sc, s);
/*
* Start the read.
*/
FSS_STAT_INC(sc, cow_copied);
dblk = btodb(FSS_CLTOB(sc, cl));
addr = scp->fc_data;
if (cl == sc->sc_clcount-1) {
todo = sc->sc_clresid;
memset((char *)addr + todo, 0, FSS_CLSIZE(sc) - todo);
} else
todo = FSS_CLSIZE(sc);
while (todo > 0) {
len = todo;
if (len > MAXPHYS)
len = MAXPHYS;
bp = getiobuf();
bp->b_flags = B_READ|B_CALL;
bp->b_bcount = len;
bp->b_bufsize = bp->b_bcount;
bp->b_error = 0;
bp->b_data = addr;
bp->b_blkno = dblk;
bp->b_proc = NULL;
bp->b_dev = sc->sc_bdev;
bp->b_vp = NULLVP;
bp->b_private = scp;
bp->b_iodone = fss_cluster_iodone;
bdev_strategy(bp);
FSS_LOCK(sc, s);
scp->fc_xfercount++;
FSS_UNLOCK(sc, s);
dblk += btodb(len);
addr += len;
todo -= len;
}
/*
* Wait for all read requests to complete.
*/
FSS_LOCK(sc, s);
while (scp->fc_xfercount > 0)
ltsleep(&scp->fc_data, PRIBIO, "cowwait", 0, &sc->sc_slock);
scp->fc_type = FSS_CACHE_VALID;
setbit(sc->sc_copied, scp->fc_cluster);
FSS_UNLOCK(sc, s);
wakeup(&sc->sc_bs_lwp);
}
/*
* Read/write clusters from/to backing store.
* For persistent snapshots must be called with cl == 0. off is the
* offset into the snapshot.
*/
static int
fss_bs_io(struct fss_softc *sc, fss_io_type rw,
u_int32_t cl, off_t off, int len, void *data)
{
int error;
off += FSS_CLTOB(sc, cl);
vn_lock(sc->sc_bs_vp, LK_EXCLUSIVE|LK_RETRY);
error = vn_rdwr((rw == FSS_READ ? UIO_READ : UIO_WRITE), sc->sc_bs_vp,
data, len, off, UIO_SYSSPACE, IO_UNIT|IO_NODELOCKED,
sc->sc_bs_lwp->l_cred, NULL, NULL);
if (error == 0) {
simple_lock(&sc->sc_bs_vp->v_interlock);
error = VOP_PUTPAGES(sc->sc_bs_vp, trunc_page(off),
round_page(off+len), PGO_CLEANIT|PGO_SYNCIO|PGO_FREE);
}
VOP_UNLOCK(sc->sc_bs_vp, 0);
return error;
}
/*
* Get a pointer to the indirect slot for this cluster.
*/
static u_int32_t *
fss_bs_indir(struct fss_softc *sc, u_int32_t cl)
{
u_int32_t icl;
int ioff;
icl = cl/(FSS_CLSIZE(sc)/sizeof(u_int32_t));
ioff = cl%(FSS_CLSIZE(sc)/sizeof(u_int32_t));
if (sc->sc_indir_cur == icl)
return &sc->sc_indir_data[ioff];
if (sc->sc_indir_dirty) {
FSS_STAT_INC(sc, indir_write);
if (fss_bs_io(sc, FSS_WRITE, sc->sc_indir_cur, 0,
FSS_CLSIZE(sc), (void *)sc->sc_indir_data) != 0)
return NULL;
setbit(sc->sc_indir_valid, sc->sc_indir_cur);
}
sc->sc_indir_dirty = 0;
sc->sc_indir_cur = icl;
if (isset(sc->sc_indir_valid, sc->sc_indir_cur)) {
FSS_STAT_INC(sc, indir_read);
if (fss_bs_io(sc, FSS_READ, sc->sc_indir_cur, 0,
FSS_CLSIZE(sc), (void *)sc->sc_indir_data) != 0)
return NULL;
} else
memset(sc->sc_indir_data, 0, FSS_CLSIZE(sc));
return &sc->sc_indir_data[ioff];
}
/*
* The kernel thread (one for every active snapshot).
*
* After wakeup it cleans the cache and runs the I/O requests.
*/
static void
fss_bs_thread(void *arg)
{
int error, len, nfreed, nio, s;
long off;
char *addr;
u_int32_t c, cl, ch, *indirp;
struct buf *bp, *nbp;
struct fss_softc *sc;
struct fss_cache *scp, *scl;
sc = arg;
scl = sc->sc_cache+sc->sc_cache_size;
nbp = getiobuf();
nfreed = nio = 1; /* Dont sleep the first time */
FSS_LOCK(sc, s);
for (;;) {
if (nfreed == 0 && nio == 0)
ltsleep(&sc->sc_bs_lwp, PVM-1, "fssbs", 0,
&sc->sc_slock);
if ((sc->sc_flags & FSS_BS_THREAD) == 0) {
sc->sc_bs_lwp = NULL;
wakeup(&sc->sc_bs_lwp);
FSS_UNLOCK(sc, s);
putiobuf(nbp);
#ifdef FSS_STATISTICS
if ((sc->sc_flags & FSS_PERSISTENT) == 0) {
printf("fss%d: cow called %" PRId64 " times,"
" copied %" PRId64 " clusters,"
" cache full %" PRId64 " times\n",
sc->sc_unit,
FSS_STAT_VAL(sc, cow_calls),
FSS_STAT_VAL(sc, cow_copied),
FSS_STAT_VAL(sc, cow_cache_full));
printf("fss%d: %" PRId64 " indir reads,"
" %" PRId64 " indir writes\n",
sc->sc_unit,
FSS_STAT_VAL(sc, indir_read),
FSS_STAT_VAL(sc, indir_write));
}
#endif /* FSS_STATISTICS */
kthread_exit(0);
}
/*
* Process I/O requests (persistent)
*/
if (sc->sc_flags & FSS_PERSISTENT) {
nfreed = nio = 0;
if ((bp = BUFQ_GET(sc->sc_bufq)) == NULL)
continue;
nio++;
if (FSS_ISVALID(sc)) {
FSS_UNLOCK(sc, s);
error = fss_bs_io(sc, FSS_READ, 0,
dbtob(bp->b_blkno), bp->b_bcount,
bp->b_data);
FSS_LOCK(sc, s);
} else
error = ENXIO;
if (error) {
bp->b_error = error;
bp->b_resid = bp->b_bcount;
} else
bp->b_resid = 0;
biodone(bp);
continue;
}
/*
* Clean the cache
*/
nfreed = 0;
for (scp = sc->sc_cache; scp < scl; scp++) {
if (scp->fc_type != FSS_CACHE_VALID)
continue;
FSS_UNLOCK(sc, s);
indirp = fss_bs_indir(sc, scp->fc_cluster);
if (indirp != NULL) {
error = fss_bs_io(sc, FSS_WRITE, sc->sc_clnext,
0, FSS_CLSIZE(sc), scp->fc_data);
} else
error = EIO;
FSS_LOCK(sc, s);
if (error == 0) {
*indirp = sc->sc_clnext++;
sc->sc_indir_dirty = 1;
} else
fss_error(sc, "write bs error %d", error);
scp->fc_type = FSS_CACHE_FREE;
nfreed++;
wakeup(&scp->fc_type);
}
if (nfreed)
wakeup(&sc->sc_cache);
/*
* Process I/O requests
*/
nio = 0;
if ((bp = BUFQ_GET(sc->sc_bufq)) == NULL)
continue;
nio++;
if (!FSS_ISVALID(sc)) {
bp->b_error = ENXIO;
bp->b_resid = bp->b_bcount;
biodone(bp);
continue;
}
/*
* First read from the snapshotted block device.
* XXX Split to only read those parts that have not
* been saved to backing store?
*/
FSS_UNLOCK(sc, s);
BUF_INIT(nbp);
nbp->b_flags = B_READ;
nbp->b_bcount = bp->b_bcount;
nbp->b_bufsize = bp->b_bcount;
nbp->b_error = 0;
nbp->b_data = bp->b_data;
nbp->b_blkno = bp->b_blkno;
nbp->b_proc = bp->b_proc;
nbp->b_dev = sc->sc_bdev;
nbp->b_vp = NULLVP;
bdev_strategy(nbp);
if (biowait(nbp) != 0) {
bp->b_resid = bp->b_bcount;
bp->b_error = nbp->b_error;
biodone(bp);
FSS_LOCK(sc, s);
continue;
}
cl = FSS_BTOCL(sc, dbtob(bp->b_blkno));
off = FSS_CLOFF(sc, dbtob(bp->b_blkno));
ch = FSS_BTOCL(sc, dbtob(bp->b_blkno)+bp->b_bcount-1);
bp->b_resid = bp->b_bcount;
addr = bp->b_data;
FSS_LOCK(sc, s);
/*
* Replace those parts that have been saved to backing store.
*/
for (c = cl; c <= ch;
c++, off = 0, bp->b_resid -= len, addr += len) {
len = FSS_CLSIZE(sc)-off;
if (len > bp->b_resid)
len = bp->b_resid;
if (isclr(sc->sc_copied, c))
continue;
FSS_UNLOCK(sc, s);
indirp = fss_bs_indir(sc, c);
FSS_LOCK(sc, s);
if (indirp == NULL || *indirp == 0) {
/*
* Not on backing store. Either in cache
* or hole in the snapshotted block device.
*/
for (scp = sc->sc_cache; scp < scl; scp++)
if (scp->fc_type == FSS_CACHE_VALID &&
scp->fc_cluster == c)
break;
if (scp < scl)
memcpy(addr, (char *)scp->fc_data+off, len);
else
memset(addr, 0, len);
continue;
}
/*
* Read from backing store.
*/
FSS_UNLOCK(sc, s);
if ((error = fss_bs_io(sc, FSS_READ, *indirp,
off, len, addr)) != 0) {
bp->b_resid = bp->b_bcount;
bp->b_error = error;
FSS_LOCK(sc, s);
break;
}
FSS_LOCK(sc, s);
}
biodone(bp);
}
}
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