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NetBSD/sys/dev/fss.c

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/* $NetBSD: fss.c,v 1.2 2003/12/13 18:59:29 hannken 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 1.2 2003/12/13 18:59:29 hannken Exp $");
#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 <miscfs/specfs/specdev.h>
#include <machine/stdarg.h>
#include "fss.h"
#include <dev/fssvar.h>
#ifdef DEBUG
#include "opt_ddb.h"
#include <ddb/ddbvar.h>
#include <machine/db_machdep.h>
#include <ddb/db_command.h>
#include <ddb/db_interface.h>
#endif
#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 */
typedef enum {
FSS_READ,
FSS_WRITE
} fss_io_type;
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 inline void fss_error(struct fss_softc *, const char *, ...);
static inline int fss_valid(struct fss_softc *);
static int fss_create_snapshot(struct fss_softc *, struct fss_set *,
struct proc *);
static int fss_delete_snapshot(struct fss_softc *, struct proc *);
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 int fss_write_cluster(struct fss_cache *, u_int32_t);
static void fss_bs_thread(void *);
static inline void block_to_cluster(struct fss_softc *, daddr_t, long,
u_int32_t *, long *);
static int fss_bs_io(struct fss_softc *, fss_io_type,
u_int32_t, long, int, caddr_t);
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;
lockinit(&sc->sc_lock, PRIBIO, "fsslock", 0, 0);
bufq_alloc(&sc->sc_bufq, BUFQ_FCFS|BUFQ_SORT_RAWBLOCK);
}
}
int
fss_open(dev_t dev, int flags, int mode, struct proc *p)
{
struct fss_softc *sc;
if (fss_dev_to_softc(dev, &sc) != 0)
return ENXIO;
return 0;
}
int
fss_close(dev_t dev, int flags, int mode, struct proc *p)
{
struct fss_softc *sc;
if (fss_dev_to_softc(dev, &sc) != 0)
return ENXIO;
return 0;
}
void
fss_strategy(struct buf *bp)
{
struct fss_softc *sc;
if ((bp->b_flags & B_READ) != B_READ ||
fss_dev_to_softc(bp->b_dev, &sc) != 0 ||
!fss_valid(sc)) {
bp->b_error = ENXIO;
bp->b_flags |= B_ERROR;
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_proc);
}
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, caddr_t data, int flag, struct proc *p)
{
int error;
struct fss_softc *sc;
struct fss_set *fss = (struct fss_set *)data;
struct fss_get *fsg = (struct fss_get *)data;
if ((error = fss_dev_to_softc(dev, &sc)) != 0)
return error;
lockmgr(&sc->sc_lock, LK_EXCLUSIVE, NULL);
error = EINVAL;
switch (cmd) {
case FSSIOCSET:
if ((flag & FWRITE) == 0)
error = EPERM;
else if ((sc->sc_flags & FSS_ACTIVE) != 0)
error = EBUSY;
else
error = fss_create_snapshot(sc, fss, p);
break;
case FSSIOCCLR:
if ((flag & FWRITE) == 0)
error = EPERM;
else if ((sc->sc_flags & FSS_ACTIVE) == 0)
error = ENXIO;
else
error = fss_delete_snapshot(sc, p);
break;
case FSSIOCGET:
if ((sc->sc_flags & FSS_ACTIVE) == FSS_ACTIVE) {
memcpy(fsg->fsg_mount, sc->sc_mntname, MNAMELEN);
fsg->fsg_csize = sc->sc_clsize;
fsg->fsg_time = sc->sc_time;
fsg->fsg_mount_size = sc->sc_clcount;
fsg->fsg_bs_size = sc->sc_clnext;
error = 0;
} else
error = ENXIO;
break;
}
lockmgr(&sc->sc_lock, LK_RELEASE, NULL);
return error;
}
int
fss_size(dev_t dev)
{
return -1;
}
int
fss_dump(dev_t dev, daddr_t blkno, caddr_t va, size_t size)
{
return ENXIO;
}
/*
* An error occured reading or writing the snapshot or backing store.
* If it is the first error log to console.
*/
static inline void
fss_error(struct fss_softc *sc, const char *fmt, ...)
{
int s;
va_list ap;
s = splbio();
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;
splx(s);
}
/*
* Check if this snapshot is still valid.
*/
static inline int
fss_valid(struct fss_softc *sc)
{
int s, valid;
s = splbio();
valid = ((sc->sc_flags & (FSS_ACTIVE|FSS_ERROR)) == FSS_ACTIVE);
splx(s);
return valid;
}
/*
* Allocate the variable sized parts of the softc and
* fork the kernel thread.
*
* The fields sc_clcount, sc_clsize, 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);
len = sc->sc_cache_size*sizeof(struct fss_cache);
sc->sc_cache = malloc(len, M_TEMP, M_WAITOK);
len = sc->sc_clsize;
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);
}
len = (sc->sc_indir_size+NBBY-1)/NBBY;
sc->sc_indir_valid = malloc(len, M_TEMP, M_ZERO|M_WAITOK);
len = sc->sc_clsize;
sc->sc_indir_data = malloc(len, M_TEMP, M_ZERO|M_WAITOK);
if ((error = kthread_create1(fss_bs_thread, sc, &sc->sc_bs_proc,
"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 i;
if ((sc->sc_flags & FSS_BS_THREAD) != 0) {
sc->sc_flags &= ~FSS_BS_THREAD;
wakeup(&sc->sc_bs_proc);
while (sc->sc_bs_proc != NULL)
tsleep(sc, PRIBIO, "fssthread", 1);
}
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++)
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;
s = splbio();
for (i = 0; i < NFSS; i++)
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 {
splx(s);
return EBUSY;
}
}
splx(s);
return 0;
}
/*
* A buffer is written to the snapshotted block device. Copy to
* backing store if needed.
*/
void
fss_copy_on_write(struct fss_softc *sc, struct buf *bp)
{
u_int32_t cl, ch, c;
#ifdef DIAGNOSTIC
/*
* Buffer written on a suspended file system. This is always an error.
*/
if (sc->sc_mount &&
(sc->sc_mount->mnt_iflag & IMNT_SUSPENDED) == IMNT_SUSPENDED) {
printf_nolog("fss%d: write while suspended, %lu@%" PRId64 "\n",
sc->sc_unit, bp->b_bcount, bp->b_blkno);
#ifdef DEBUG
db_stack_trace_print((db_expr_t)__builtin_frame_address(0),
TRUE, 65535, "", printf_nolog);
#endif /* DEBUG */
}
#endif /* DIAGNOSTIC */
if (!fss_valid(sc))
return;
sc->sc_cowcount++;
FSS_STAT_INC(sc, cow_calls);
block_to_cluster(sc, bp->b_blkno, 0, &cl, NULL);
block_to_cluster(sc, bp->b_blkno, bp->b_bcount-1, &ch, NULL);
for (c = cl; c <= ch; c++) {
if (!fss_valid(sc))
break;
fss_read_cluster(sc, c);
}
if (--sc->sc_cowcount == 0)
wakeup(&sc->sc_cowcount);
}
/*
* Lookup and open needed files.
*
* Returns dev and size of the underlying block device.
* Initializes the fields sc_mntname, sc_bs_vp, sc_mount and sc_strategy
*/
static int
fss_create_files(struct fss_softc *sc, struct fss_set *fss,
dev_t *bdev, off_t *bsize, struct proc *p)
{
int error;
struct partinfo dpart;
struct statfs statfs;
struct nameidata nd;
const struct bdevsw *bdevsw;
/*
* Get the mounted file system.
*/
NDINIT(&nd, LOOKUP, FOLLOW, UIO_USERSPACE, fss->fss_mount, p);
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;
/*
* Get the block device it is mounted on.
*/
error = VFS_STATFS(sc->sc_mount, &statfs, p);
vrele(nd.ni_vp);
if (error != 0)
return error;
memcpy(sc->sc_mntname, statfs.f_mntonname, MNAMELEN);
NDINIT(&nd, LOOKUP, FOLLOW, UIO_SYSSPACE, statfs.f_mntfromname, p);
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, p->p_ucred, p);
if (error) {
vrele(nd.ni_vp);
return error;
}
*bdev = nd.ni_vp->v_rdev;
*bsize = (off_t)dpart.disklab->d_secsize*dpart.part->p_size;
vrele(nd.ni_vp);
if ((bdevsw = bdevsw_lookup(*bdev)) == NULL)
return EINVAL;
sc->sc_strategy = bdevsw->d_strategy;
/*
* Get the backing store
*/
NDINIT(&nd, LOOKUP, FOLLOW, UIO_USERSPACE, fss->fss_bstore, p);
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 (nd.ni_vp->v_mount == sc->sc_mount)
return EDEADLK;
if (sc->sc_bs_vp->v_type == VREG) {
error = VFS_STATFS(sc->sc_bs_vp->v_mount, &statfs, p);
if (error != 0)
return error;
sc->sc_bs_bsize = statfs.f_iosize;
} else
sc->sc_bs_bsize = DEV_BSIZE;
/*
* 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, p->p_ucred, p, 0, 0)) != 0)
return error;
return 0;
}
/*
* Create a snapshot.
*/
static int
fss_create_snapshot(struct fss_softc *sc, struct fss_set *fss, struct proc *p)
{
int len, error;
dev_t bdev;
off_t bsize;
/*
* Open needed files.
*/
if ((error = fss_create_files(sc, fss, &bdev, &bsize, p)) != 0)
goto bad;
/*
* Set parameters.
*/
if (fss->fss_csize == 0)
sc->sc_clsize = MAXPHYS;
else if (fss->fss_csize < 0 || (fss->fss_csize & (DEV_BSIZE-1)) != 0) {
error = EINVAL;
goto bad;
} else if (bsize/fss->fss_csize > FSS_CLUSTER_MAX)
sc->sc_clsize = (bsize/FSS_CLUSTER_MAX+DEV_BSIZE-1) &
~(DEV_BSIZE-1);
else
sc->sc_clsize = fss->fss_csize;
if (sc->sc_clsize <= 8192)
sc->sc_cache_size = 32;
else if (sc->sc_clsize <= 65536)
sc->sc_cache_size = 8;
else
sc->sc_cache_size = 4;
block_to_cluster(sc, btodb(bsize)-1, DEV_BSIZE-1,
&sc->sc_clcount, &sc->sc_cllast);
sc->sc_clcount += 1;
sc->sc_cllast += 1;
len = sc->sc_clcount*sizeof(u_int32_t);
sc->sc_indir_size = (len+sc->sc_clsize-1)/sc->sc_clsize;
sc->sc_clnext = sc->sc_indir_size;
sc->sc_indir_cur = 0;
if ((error = fss_softc_alloc(sc)) != 0)
goto bad;
/* XXX FSSNAP_PREPARE */
/*
* Activate the snapshot.
*/
if ((error = vfs_write_suspend(sc->sc_mount)) != 0)
goto bad;
microtime(&sc->sc_time);
/* XXX FSSNAP_CREATE */
if (error == 0) {
sc->sc_flags |= FSS_ACTIVE;
sc->sc_bdev = bdev;
}
vfs_write_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, sc->sc_clsize,
sc->sc_cache_size, sc->sc_indir_size);
#endif
return 0;
bad:
fss_softc_free(sc);
if (sc->sc_bs_vp != NULL)
vn_close(sc->sc_bs_vp, FREAD|FWRITE, p->p_ucred, p);
sc->sc_bs_vp = NULL;
return error;
}
/*
* Delete a snapshot.
*/
static int
fss_delete_snapshot(struct fss_softc *sc, struct proc *p)
{
int s;
s = splbio();
sc->sc_flags &= ~(FSS_ACTIVE|FSS_ERROR);
splx(s);
while (sc->sc_cowcount > 0) {
tsleep(&sc->sc_cowcount, PRIBIO, "cowwait1", 0);
}
sc->sc_mount = NULL;
sc->sc_bdev = NODEV;
fss_softc_free(sc);
vn_close(sc->sc_bs_vp, FREAD|FWRITE, p->p_ucred, p);
sc->sc_bs_vp = NULL;
/* XXX FSSNAP_DESTROY */
FSS_STAT_CLEAR(sc);
return 0;
}
/*
* Convert disk block with offset to backing store cluster with offset.
*/
static inline void
block_to_cluster(struct fss_softc *sc, daddr_t blkno, long off,
u_int32_t *cblk, long *coff)
{
blkno = dbtob(blkno)+off;
if (cblk != NULL)
*cblk = blkno/sc->sc_clsize;
if (coff != NULL)
*coff = blkno%sc->sc_clsize;
}
/*
* 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;
s = splbio();
if (bp->b_flags & B_EINTR)
fss_error(scp->fc_softc, "fs read interrupted");
if (bp->b_flags & B_ERROR)
fss_error(scp->fc_softc, "fs read error %d", bp->b_error);
if (bp->b_vp != NULL)
brelvp(bp);
if (--scp->fc_xfercount == 0)
wakeup(&scp->fc_data);
pool_put(&bufpool, bp);
splx(s);
}
/*
* 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;
caddr_t 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;
restart:
if (isset(sc->sc_copied, cl)) {
return;
}
for (scp = sc->sc_cache; scp < scl; scp++)
if (scp->fc_type != FSS_CACHE_FREE &&
scp->fc_cluster == cl) {
tsleep(&scp->fc_type, PRIBIO, "cowwait2", 0);
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);
tsleep(&sc->sc_cache, PRIBIO, "cowwait3", 0);
goto restart;
}
/*
* Start the read.
*/
FSS_STAT_INC(sc, cow_copied);
dblk = cl*btodb(sc->sc_clsize);
addr = scp->fc_data;
if (cl == sc->sc_clcount-1) {
todo = sc->sc_cllast;
memset(addr+todo, 0, sc->sc_clsize-todo);
} else
todo = sc->sc_clsize;
while (todo > 0) {
len = todo;
if (len > MAXPHYS)
len = MAXPHYS;
s = splbio();
bp = pool_get(&bufpool, PR_WAITOK);
splx(s);
BUF_INIT(bp);
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 = bp->b_rawblkno = 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;
(*sc->sc_strategy)(bp);
s = splbio();
scp->fc_xfercount++;
splx(s);
dblk += btodb(len);
addr += len;
todo -= len;
}
/*
* Wait for all read requests to complete.
*/
s = splbio();
while (scp->fc_xfercount > 0)
tsleep(&scp->fc_data, PRIBIO, "cowwait", 0);
splx(s);
scp->fc_type = FSS_CACHE_VALID;
setbit(sc->sc_copied, scp->fc_cluster);
wakeup(&sc->sc_bs_proc);
}
/*
* Write a cluster from the cache to the backing store.
*/
static int
fss_write_cluster(struct fss_cache *scp, u_int32_t cl)
{
int s, error, todo, len, nra;
daddr_t nbn;
caddr_t addr;
off_t pos;
struct buf *bp;
struct vnode *vp;
struct fss_softc *sc;
error = 0;
sc = scp->fc_softc;
pos = (off_t)cl*sc->sc_clsize;
addr = scp->fc_data;
todo = sc->sc_clsize;
while (todo > 0) {
vn_lock(sc->sc_bs_vp, LK_EXCLUSIVE|LK_RETRY);
error = VOP_BMAP(sc->sc_bs_vp, pos/sc->sc_bs_bsize,
&vp, &nbn, &nra);
VOP_UNLOCK(sc->sc_bs_vp, 0);
if (error == 0 && nbn == (daddr_t)-1)
error = EIO;
if (error)
break;
len = (nra+1)*sc->sc_bs_bsize-pos%sc->sc_bs_bsize;
if (len > todo)
len = todo;
s = splbio();
bp = pool_get(&bufpool, PR_WAITOK);
splx(s);
BUF_INIT(bp);
bp->b_flags = B_CALL;
bp->b_bcount = len;
bp->b_bufsize = bp->b_bcount;
bp->b_error = 0;
bp->b_data = addr;
bp->b_blkno = bp->b_rawblkno = nbn+btodb(pos%sc->sc_bs_bsize);
bp->b_proc = NULL;
bp->b_vp = NULLVP;
bp->b_private = scp;
bp->b_iodone = fss_cluster_iodone;
bgetvp(vp, bp);
bp->b_vp->v_numoutput++;
VOP_STRATEGY(bp);
s = splbio();
scp->fc_xfercount++;
splx(s);
pos += len;
addr += len;
todo -= len;
}
/*
* Wait for all write requests to complete.
*/
s = splbio();
while (scp->fc_xfercount > 0)
tsleep(&scp->fc_data, PRIBIO, "bswwait", 0);
splx(s);
return error;
}
/*
* Read/write clusters from/to backing store.
*/
static int
fss_bs_io(struct fss_softc *sc, fss_io_type rw,
u_int32_t cl, long off, int len, caddr_t data)
{
int s, error, todo, count, nra;
off_t pos;
daddr_t nbn;
struct buf *bp;
struct vnode *vp;
todo = len;
pos = (off_t)cl*sc->sc_clsize+off;
error = 0;
while (todo > 0) {
vn_lock(sc->sc_bs_vp, LK_EXCLUSIVE|LK_RETRY);
error = VOP_BMAP(sc->sc_bs_vp, pos/sc->sc_bs_bsize,
&vp, &nbn, &nra);
VOP_UNLOCK(sc->sc_bs_vp, 0);
if (error == 0 && nbn == (daddr_t)-1)
error = EIO;
if (error)
break;
count = (nra+1)*sc->sc_bs_bsize-pos%sc->sc_bs_bsize;
if (count > todo)
count = todo;
s = splbio();
bp = pool_get(&bufpool, PR_WAITOK);
splx(s);
BUF_INIT(bp);
bp->b_flags = (rw == FSS_READ ? B_READ : 0);
bp->b_bcount = count;
bp->b_bufsize = bp->b_bcount;
bp->b_error = 0;
bp->b_data = data;
bp->b_blkno = bp->b_rawblkno = nbn+btodb(pos%sc->sc_bs_bsize);
bp->b_proc = NULL;
bp->b_vp = NULLVP;
bgetvp(vp, bp);
if ((bp->b_flags & B_READ) == 0)
bp->b_vp->v_numoutput++;
VOP_STRATEGY(bp);
error = biowait(bp);
if (bp->b_vp != NULL)
brelvp(bp);
s = splbio();
pool_put(&bufpool, bp);
splx(s);
if (error)
break;
todo -= count;
data += count;
pos += count;
}
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/(sc->sc_clsize/sizeof(u_int32_t));
ioff = cl%(sc->sc_clsize/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,
sc->sc_clsize, (caddr_t)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,
sc->sc_clsize, (caddr_t)sc->sc_indir_data) != 0)
return NULL;
} else
memset(sc->sc_indir_data, 0, sc->sc_clsize);
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;
caddr_t 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;
s = splbio();
nbp = pool_get(&bufpool, PR_WAITOK);
splx(s);
nfreed = nio = 1; /* Dont sleep the first time */
for (;;) {
if (nfreed == 0 && nio == 0)
tsleep(&sc->sc_bs_proc, PVM, "fssbs", 0);
if ((sc->sc_flags & FSS_BS_THREAD) == 0) {
s = splbio();
pool_put(&bufpool, nbp);
splx(s);
#ifdef FSS_STATISTICS
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 */
sc->sc_bs_proc = NULL;
kthread_exit(0);
}
/*
* Clean the cache
*/
nfreed = 0;
for (scp = sc->sc_cache; scp < scl; scp++) {
if (scp->fc_type != FSS_CACHE_VALID)
continue;
indirp = fss_bs_indir(sc, scp->fc_cluster);
if (indirp != NULL) {
error = fss_write_cluster(scp, sc->sc_clnext);
} else
error = EIO;
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_valid(sc)) {
bp->b_error = ENXIO;
bp->b_flags |= B_ERROR;
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?
*/
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 = nbp->b_rawblkno = bp->b_blkno;
nbp->b_proc = bp->b_proc;
nbp->b_dev = sc->sc_bdev;
nbp->b_vp = NULLVP;
(*sc->sc_strategy)(nbp);
if (biowait(nbp) != 0) {
bp->b_resid = bp->b_bcount;
bp->b_error = nbp->b_error;
bp->b_flags |= B_ERROR;
biodone(bp);
continue;
}
block_to_cluster(sc, bp->b_blkno, 0, &cl, &off);
block_to_cluster(sc, bp->b_blkno, bp->b_bcount-1, &ch, NULL);
bp->b_resid = bp->b_bcount;
addr = bp->b_data;
/*
* 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 = sc->sc_clsize-off;
if (len > bp->b_resid)
len = bp->b_resid;
if (isclr(sc->sc_copied, c))
continue;
indirp = fss_bs_indir(sc, c);
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, scp->fc_data+off, len);
else
memset(addr, 0, len);
continue;
}
/*
* Read from backing store.
*/
if ((error = fss_bs_io(sc, FSS_READ, *indirp,
off, len, addr)) != 0) {
bp->b_resid = bp->b_bcount;
bp->b_error = error;
bp->b_flags |= B_ERROR;
break;
}
}
biodone(bp);
}
}
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