libzpool/common/kernel.c

/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
 * Copyright (c) 2012, 2015 by Delphix. All rights reserved.
 * Copyright (c) 2013, Joyent, Inc.  All rights reserved.
 */

#include <assert.h>
#include <fcntl.h>
#include <poll.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <zlib.h>
#include <libgen.h>
#include <sys/spa.h>
#include <sys/stat.h>
#include <sys/processor.h>
#include <sys/zfs_context.h>
#include <sys/rrwlock.h>
#include <sys/zmod.h>
#include <sys/utsname.h>
#include <sys/systeminfo.h>

/*
 * Emulation of kernel services in userland.
 */

int aok;
uint64_t physmem;
vnode_t *rootdir = (vnode_t *)0xabcd1234;
char hw_serial[HW_HOSTID_LEN];
kmutex_t cpu_lock;
vmem_t *zio_arena = NULL;

/* If set, all blocks read will be copied to the specified directory. */
char *vn_dumpdir = NULL;

struct utsname utsname = {
    "userland", "libzpool", "1", "1", "na"
};

/* this only exists to have its address taken */
struct proc p0;

/*
 * =========================================================================
 * threads
 * =========================================================================
 */
/*ARGSUSED*/
kthread_t *
zk_thread_create(void (*func)(), void *arg, uint64_t len)
{
    thread_t tid;

    ASSERT0(len);
    VERIFY(thr_create(0, 0, (void *(*)(void *))func, arg, THR_DETACHED,
        &tid) == 0);

    return ((void *)(uintptr_t)tid);
}

/*
 * =========================================================================
 * kstats
 * =========================================================================
 */
/*ARGSUSED*/
kstat_t *
kstat_create(const char *module, int instance, const char *name,
    const char *class, uchar_t type, ulong_t ndata, uchar_t ks_flag)
{
    return (NULL);
}

/*ARGSUSED*/
void
kstat_named_init(kstat_named_t *knp, const char *name, uchar_t type)
{}

/*ARGSUSED*/
void
kstat_install(kstat_t *ksp)
{}

/*ARGSUSED*/
void
kstat_delete(kstat_t *ksp)
{}

/*ARGSUSED*/
void
kstat_waitq_enter(kstat_io_t *kiop)
{}

/*ARGSUSED*/
void
kstat_waitq_exit(kstat_io_t *kiop)
{}

/*ARGSUSED*/
void
kstat_runq_enter(kstat_io_t *kiop)
{}

/*ARGSUSED*/
void
kstat_runq_exit(kstat_io_t *kiop)
{}

/*ARGSUSED*/
void
kstat_waitq_to_runq(kstat_io_t *kiop)
{}

/*ARGSUSED*/
void
kstat_runq_back_to_waitq(kstat_io_t *kiop)
{}

/*
 * =========================================================================
 * mutexes
 * =========================================================================
 */
void
zmutex_init(kmutex_t *mp)
{
    mp->m_owner = NULL;
    mp->initialized = B_TRUE;
    (void) _mutex_init(&mp->m_lock, USYNC_THREAD, NULL);
}

void
zmutex_destroy(kmutex_t *mp)
{
    ASSERT(mp->initialized == B_TRUE);
    ASSERT(mp->m_owner == NULL);
    (void) _mutex_destroy(&(mp)->m_lock);
    mp->m_owner = (void *)-1UL;
    mp->initialized = B_FALSE;
}

void
zmutex_enter(kmutex_t *mp)
{
    ASSERT(mp->initialized == B_TRUE);
    ASSERT(mp->m_owner != (void *)-1UL);
    ASSERT(mp->m_owner != curthread);
    VERIFY(mutex_lock(&mp->m_lock) == 0);
    ASSERT(mp->m_owner == NULL);
    mp->m_owner = curthread;
}

int
mutex_tryenter(kmutex_t *mp)
{
    ASSERT(mp->initialized == B_TRUE);
    ASSERT(mp->m_owner != (void *)-1UL);
    if (0 == mutex_trylock(&mp->m_lock)) {
        ASSERT(mp->m_owner == NULL);
        mp->m_owner = curthread;
        return (1);
    } else {
        return (0);
    }
}

void
zmutex_exit(kmutex_t *mp)
{
    ASSERT(mp->initialized == B_TRUE);
    ASSERT(mutex_owner(mp) == curthread);
    mp->m_owner = NULL;
    VERIFY(mutex_unlock(&mp->m_lock) == 0);
}

void *
mutex_owner(kmutex_t *mp)
{
    ASSERT(mp->initialized == B_TRUE);
    return (mp->m_owner);
}

/*
 * =========================================================================
 * rwlocks
 * =========================================================================
 */
/*ARGSUSED*/
void
rw_init(krwlock_t *rwlp, char *name, int type, void *arg)
{
    rwlock_init(&rwlp->rw_lock, USYNC_THREAD, NULL);
    rwlp->rw_owner = NULL;
    rwlp->initialized = B_TRUE;
}

void
rw_destroy(krwlock_t *rwlp)
{
    rwlock_destroy(&rwlp->rw_lock);
    rwlp->rw_owner = (void *)-1UL;
    rwlp->initialized = B_FALSE;
}

void
rw_enter(krwlock_t *rwlp, krw_t rw)
{
    ASSERT(!RW_LOCK_HELD(rwlp));
    ASSERT(rwlp->initialized == B_TRUE);
    ASSERT(rwlp->rw_owner != (void *)-1UL);
    ASSERT(rwlp->rw_owner != curthread);

    if (rw == RW_WRITER)
        VERIFY(rw_wrlock(&rwlp->rw_lock) == 0);
    else
        VERIFY(rw_rdlock(&rwlp->rw_lock) == 0);

    rwlp->rw_owner = curthread;
}

void
rw_exit(krwlock_t *rwlp)
{
    ASSERT(rwlp->initialized == B_TRUE);
    ASSERT(rwlp->rw_owner != (void *)-1UL);

    rwlp->rw_owner = NULL;
    VERIFY(rw_unlock(&rwlp->rw_lock) == 0);
}

int
rw_tryenter(krwlock_t *rwlp, krw_t rw)
{
    int rv;

    ASSERT(rwlp->initialized == B_TRUE);
    ASSERT(rwlp->rw_owner != (void *)-1UL);

    if (rw == RW_WRITER)
        rv = rw_trywrlock(&rwlp->rw_lock);
    else
        rv = rw_tryrdlock(&rwlp->rw_lock);

    if (rv == 0) {
        rwlp->rw_owner = curthread;
        return (1);
    }

    return (0);
}

/*ARGSUSED*/
int
rw_tryupgrade(krwlock_t *rwlp)
{
    ASSERT(rwlp->initialized == B_TRUE);
    ASSERT(rwlp->rw_owner != (void *)-1UL);

    return (0);
}

/*
 * =========================================================================
 * condition variables
 * =========================================================================
 */
/*ARGSUSED*/
void
cv_init(kcondvar_t *cv, char *name, int type, void *arg)
{
    VERIFY(cond_init(cv, type, NULL) == 0);
}

void
cv_destroy(kcondvar_t *cv)
{
    VERIFY(cond_destroy(cv) == 0);
}

void
cv_wait(kcondvar_t *cv, kmutex_t *mp)
{
    ASSERT(mutex_owner(mp) == curthread);
    mp->m_owner = NULL;
    int ret = cond_wait(cv, &mp->m_lock);
    VERIFY(ret == 0 || ret == EINTR);
    mp->m_owner = curthread;
}

clock_t
cv_timedwait(kcondvar_t *cv, kmutex_t *mp, clock_t abstime)
{
    int error;
    timestruc_t ts;
    clock_t delta;

top:
    delta = abstime - ddi_get_lbolt();
    if (delta <= 0)
        return (-1);

    ts.tv_sec = delta / hz;
    ts.tv_nsec = (delta % hz) * (NANOSEC / hz);

    ASSERT(mutex_owner(mp) == curthread);
    mp->m_owner = NULL;
    error = cond_reltimedwait(cv, &mp->m_lock, &ts);
    mp->m_owner = curthread;

    if (error == ETIME)
        return (-1);

    if (error == EINTR)
        goto top;

    ASSERT(error == 0);

    return (1);
}

/*ARGSUSED*/
clock_t
cv_timedwait_hires(kcondvar_t *cv, kmutex_t *mp, hrtime_t tim, hrtime_t res,
    int flag)
{
    int error;
    timestruc_t ts;
    hrtime_t delta;

    ASSERT(flag == 0 || flag == CALLOUT_FLAG_ABSOLUTE);

top:
    delta = tim;
    if (flag & CALLOUT_FLAG_ABSOLUTE)
        delta -= gethrtime();

    if (delta <= 0)
        return (-1);

    ts.tv_sec = delta / NANOSEC;
    ts.tv_nsec = delta % NANOSEC;

    ASSERT(mutex_owner(mp) == curthread);
    mp->m_owner = NULL;
    error = cond_reltimedwait(cv, &mp->m_lock, &ts);
    mp->m_owner = curthread;

    if (error == ETIME)
        return (-1);

    if (error == EINTR)
        goto top;

    ASSERT(error == 0);

    return (1);
}

void
cv_signal(kcondvar_t *cv)
{
    VERIFY(cond_signal(cv) == 0);
}

void
cv_broadcast(kcondvar_t *cv)
{
    VERIFY(cond_broadcast(cv) == 0);
}

/*
 * =========================================================================
 * vnode operations
 * =========================================================================
 */
/*
 * Note: for the xxxat() versions of these functions, we assume that the
 * starting vp is always rootdir (which is true for spa_directory.c, the only
 * ZFS consumer of these interfaces).  We assert this is true, and then emulate
 * them by adding '/' in front of the path.
 */

/*ARGSUSED*/
int
vn_open(char *path, int x1, int flags, int mode, vnode_t **vpp, int x2, int x3)
{
    int fd;
    int dump_fd;
    vnode_t *vp;
    int old_umask;
    char realpath[MAXPATHLEN];
    struct stat64 st;

    /*
     * If we're accessing a real disk from userland, we need to use
     * the character interface to avoid caching.  This is particularly
     * important if we're trying to look at a real in-kernel storage
     * pool from userland, e.g. via zdb, because otherwise we won't
     * see the changes occurring under the segmap cache.
     * On the other hand, the stupid character device returns zero
     * for its size.  So -- gag -- we open the block device to get
     * its size, and remember it for subsequent VOP_GETATTR().
     */
    if (strncmp(path, "/dev/", 5) == 0) {
        char *dsk;
        fd = open64(path, O_RDONLY);
        if (fd == -1)
            return (errno);
        if (fstat64(fd, &st) == -1) {
            close(fd);
            return (errno);
        }
        close(fd);
        (void) sprintf(realpath, "%s", path);
        dsk = strstr(path, "/dsk/");
        if (dsk != NULL)
            (void) sprintf(realpath + (dsk - path) + 1, "r%s",
                dsk + 1);
    } else {
        (void) sprintf(realpath, "%s", path);
        if (!(flags & FCREAT) && stat64(realpath, &st) == -1)
            return (errno);
    }

    if (flags & FCREAT)
        old_umask = umask(0);

    /*
     * The construct 'flags - FREAD' conveniently maps combinations of
     * FREAD and FWRITE to the corresponding O_RDONLY, O_WRONLY, and O_RDWR.
     */
    fd = open64(realpath, flags - FREAD, mode);

    if (flags & FCREAT)
        (void) umask(old_umask);

    if (vn_dumpdir != NULL) {
        char dumppath[MAXPATHLEN];
        (void) snprintf(dumppath, sizeof (dumppath),
            "%s/%s", vn_dumpdir, basename(realpath));
        dump_fd = open64(dumppath, O_CREAT | O_WRONLY, 0666);
        if (dump_fd == -1)
            return (errno);
    } else {
        dump_fd = -1;
    }

    if (fd == -1)
        return (errno);

    if (fstat64(fd, &st) == -1) {
        close(fd);
        return (errno);
    }

    (void) fcntl(fd, F_SETFD, FD_CLOEXEC);

    *vpp = vp = umem_zalloc(sizeof (vnode_t), UMEM_NOFAIL);

    vp->v_fd = fd;
    vp->v_size = st.st_size;
    vp->v_path = spa_strdup(path);
    vp->v_dump_fd = dump_fd;

    return (0);
}

/*ARGSUSED*/
int
vn_openat(char *path, int x1, int flags, int mode, vnode_t **vpp, int x2,
    int x3, vnode_t *startvp, int fd)
{
    char *realpath = umem_alloc(strlen(path) + 2, UMEM_NOFAIL);
    int ret;

    ASSERT(startvp == rootdir);
    (void) sprintf(realpath, "/%s", path);

    /* fd ignored for now, need if want to simulate nbmand support */
    ret = vn_open(realpath, x1, flags, mode, vpp, x2, x3);

    umem_free(realpath, strlen(path) + 2);

    return (ret);
}

/*ARGSUSED*/
int
vn_rdwr(int uio, vnode_t *vp, void *addr, ssize_t len, offset_t offset,
    int x1, int x2, rlim64_t x3, void *x4, ssize_t *residp)
{
    ssize_t iolen, split;

    if (uio == UIO_READ) {
        iolen = pread64(vp->v_fd, addr, len, offset);
        if (vp->v_dump_fd != -1) {
            int status =
                pwrite64(vp->v_dump_fd, addr, iolen, offset);
            ASSERT(status != -1);
        }
    } else {
        /*
         * To simulate partial disk writes, we split writes into two
         * system calls so that the process can be killed in between.
         */
        int sectors = len >> SPA_MINBLOCKSHIFT;
        split = (sectors > 0 ? rand() % sectors : 0) <<
            SPA_MINBLOCKSHIFT;
        iolen = pwrite64(vp->v_fd, addr, split, offset);
        iolen += pwrite64(vp->v_fd, (char *)addr + split,
            len - split, offset + split);
    }

    if (iolen == -1)
        return (errno);
    if (residp)
        *residp = len - iolen;
    else if (iolen != len)
        return (EIO);
    return (0);
}

void
vn_close(vnode_t *vp)
{
    close(vp->v_fd);
    if (vp->v_dump_fd != -1)
        close(vp->v_dump_fd);
    spa_strfree(vp->v_path);
    umem_free(vp, sizeof (vnode_t));
}

/*
 * At a minimum we need to update the size since vdev_reopen()
 * will no longer call vn_openat().
 */
int
fop_getattr(vnode_t *vp, vattr_t *vap)
{
    struct stat64 st;

    if (fstat64(vp->v_fd, &st) == -1) {
        close(vp->v_fd);
        return (errno);
    }

    vap->va_size = st.st_size;
    return (0);
}

#ifdef ZFS_DEBUG

/*
 * =========================================================================
 * Figure out which debugging statements to print
 * =========================================================================
 */

static char *dprintf_string;
static int dprintf_print_all;

int
dprintf_find_string(const char *string)
{
    char *tmp_str = dprintf_string;
    int len = strlen(string);

    /*
     * Find out if this is a string we want to print.
     * String format: file1.c,function_name1,file2.c,file3.c
     */

    while (tmp_str != NULL) {
        if (strncmp(tmp_str, string, len) == 0 &&
            (tmp_str[len] == ',' || tmp_str[len] == '\0'))
            return (1);
        tmp_str = strchr(tmp_str, ',');
        if (tmp_str != NULL)
            tmp_str++; /* Get rid of , */
    }
    return (0);
}

void
dprintf_setup(int *argc, char **argv)
{
    int i, j;

    /*
     * Debugging can be specified two ways: by setting the
     * environment variable ZFS_DEBUG, or by including a
     * "debug=..."  argument on the command line.  The command
     * line setting overrides the environment variable.
     */

    for (i = 1; i < *argc; i++) {
        int len = strlen("debug=");
        /* First look for a command line argument */
        if (strncmp("debug=", argv[i], len) == 0) {
            dprintf_string = argv[i] + len;
            /* Remove from args */
            for (j = i; j < *argc; j++)
                argv[j] = argv[j+1];
            argv[j] = NULL;
            (*argc)--;
        }
    }

    if (dprintf_string == NULL) {
        /* Look for ZFS_DEBUG environment variable */
        dprintf_string = getenv("ZFS_DEBUG");
    }

    /*
     * Are we just turning on all debugging?
     */
    if (dprintf_find_string("on"))
        dprintf_print_all = 1;

    if (dprintf_string != NULL)
        zfs_flags |= ZFS_DEBUG_DPRINTF;
}

/*
 * =========================================================================
 * debug printfs
 * =========================================================================
 */
void
__dprintf(const char *file, const char *func, int line, const char *fmt, ...)
{
    const char *newfile;
    va_list adx;

    /*
     * Get rid of annoying "../common/" prefix to filename.
     */
    newfile = strrchr(file, '/');
    if (newfile != NULL) {
        newfile = newfile + 1; /* Get rid of leading / */
    } else {
        newfile = file;
    }

    if (dprintf_print_all ||
        dprintf_find_string(newfile) ||
        dprintf_find_string(func)) {
        /* Print out just the function name if requested */
        flockfile(stdout);
        if (dprintf_find_string("pid"))
            (void) printf("%d ", getpid());
        if (dprintf_find_string("tid"))
            (void) printf("%u ", thr_self());
        if (dprintf_find_string("cpu"))
            (void) printf("%u ", getcpuid());
        if (dprintf_find_string("time"))
            (void) printf("%llu ", gethrtime());
        if (dprintf_find_string("long"))
            (void) printf("%s, line %d: ", newfile, line);
        (void) printf("%s: ", func);
        va_start(adx, fmt);
        (void) vprintf(fmt, adx);
        va_end(adx);
        funlockfile(stdout);
    }
}

#endif /* ZFS_DEBUG */

/*
 * =========================================================================
 * cmn_err() and panic()
 * =========================================================================
 */
static char ce_prefix[CE_IGNORE][10] = { "", "NOTICE: ", "WARNING: ", "" };
static char ce_suffix[CE_IGNORE][2] = { "", "\n", "\n", "" };

void
vpanic(const char *fmt, va_list adx)
{
    char buf[512];
    (void) vsnprintf(buf, 512, fmt, adx);
    assfail(buf, NULL, 0);
}

void
panic(const char *fmt, ...)
{
    va_list adx;

    va_start(adx, fmt);
    vpanic(fmt, adx);
    va_end(adx);
}

void
vcmn_err(int ce, const char *fmt, va_list adx)
{
    if (ce == CE_PANIC)
        vpanic(fmt, adx);
    if (ce != CE_NOTE) {    /* suppress noise in userland stress testing */
        (void) fprintf(stderr, "%s", ce_prefix[ce]);
        (void) vfprintf(stderr, fmt, adx);
        (void) fprintf(stderr, "%s", ce_suffix[ce]);
    }
}

/*PRINTFLIKE2*/
void
cmn_err(int ce, const char *fmt, ...)
{
    va_list adx;

    va_start(adx, fmt);
    vcmn_err(ce, fmt, adx);
    va_end(adx);
}

/*
 * =========================================================================
 * kobj interfaces
 * =========================================================================
 */
struct _buf *
kobj_open_file(char *name)
{
    struct _buf *file;
    vnode_t *vp;

    /* set vp as the _fd field of the file */
    if (vn_openat(name, UIO_SYSSPACE, FREAD, 0, &vp, 0, 0, rootdir,
        -1) != 0)
        return ((void *)-1UL);

    file = umem_zalloc(sizeof (struct _buf), UMEM_NOFAIL);
    file->_fd = (intptr_t)vp;
    return (file);
}

int
kobj_read_file(struct _buf *file, char *buf, unsigned size, unsigned off)
{
    ssize_t resid;

    vn_rdwr(UIO_READ, (vnode_t *)file->_fd, buf, size, (offset_t)off,
        UIO_SYSSPACE, 0, 0, 0, &resid);

    return (size - resid);
}

void
kobj_close_file(struct _buf *file)
{
    vn_close((vnode_t *)file->_fd);
    umem_free(file, sizeof (struct _buf));
}

int
kobj_get_filesize(struct _buf *file, uint64_t *size)
{
    struct stat64 st;
    vnode_t *vp = (vnode_t *)file->_fd;

    if (fstat64(vp->v_fd, &st) == -1) {
        vn_close(vp);
        return (errno);
    }
    *size = st.st_size;
    return (0);
}

/*
 * =========================================================================
 * misc routines
 * =========================================================================
 */

void
delay(clock_t ticks)
{
    poll(0, 0, ticks * (1000 / hz));
}

/*
 * Find highest one bit set.
 *  Returns bit number + 1 of highest bit that is set, otherwise returns 0.
 */
int
highbit64(uint64_t i)
{
    int h = 1;

    if (i == 0)
        return (0);
    if (i & 0xffffffff00000000ULL) {
        h += 32; i >>= 32;
    }
    if (i & 0xffff0000) {
        h += 16; i >>= 16;
    }
    if (i & 0xff00) {
        h += 8; i >>= 8;
    }
    if (i & 0xf0) {
        h += 4; i >>= 4;
    }
    if (i & 0xc) {
        h += 2; i >>= 2;
    }
    if (i & 0x2) {
        h += 1;
    }
    return (h);
}

static int random_fd = -1, urandom_fd = -1;

static int
random_get_bytes_common(uint8_t *ptr, size_t len, int fd)
{
    size_t resid = len;
    ssize_t bytes;

    ASSERT(fd != -1);

    while (resid != 0) {
        bytes = read(fd, ptr, resid);
        ASSERT3S(bytes, >=, 0);
        ptr += bytes;
        resid -= bytes;
    }

    return (0);
}

int
random_get_bytes(uint8_t *ptr, size_t len)
{
    return (random_get_bytes_common(ptr, len, random_fd));
}

int
random_get_pseudo_bytes(uint8_t *ptr, size_t len)
{
    return (random_get_bytes_common(ptr, len, urandom_fd));
}

int
ddi_strtoul(const char *hw_serial, char **nptr, int base, unsigned long *result)
{
    char *end;

    *result = strtoul(hw_serial, &end, base);
    if (*result == 0)
        return (errno);
    return (0);
}

int
ddi_strtoull(const char *str, char **nptr, int base, u_longlong_t *result)
{
    char *end;

    *result = strtoull(str, &end, base);
    if (*result == 0)
        return (errno);
    return (0);
}

/* ARGSUSED */
cyclic_id_t
cyclic_add(cyc_handler_t *hdlr, cyc_time_t *when)
{
    return (1);
}

/* ARGSUSED */
void
cyclic_remove(cyclic_id_t id)
{
}

/* ARGSUSED */
int
cyclic_reprogram(cyclic_id_t id, hrtime_t expiration)
{
    return (1);
}

/*
 * =========================================================================
 * kernel emulation setup & teardown
 * =========================================================================
 */
static int
umem_out_of_memory(void)
{
    char errmsg[] = "out of memory -- generating core dump\n";

    write(fileno(stderr), errmsg, sizeof (errmsg));
    abort();
    return (0);
}

void
kernel_init(int mode)
{
    extern uint_t rrw_tsd_key;

    umem_nofail_callback(umem_out_of_memory);

    physmem = sysconf(_SC_PHYS_PAGES);

    dprintf("physmem = %llu pages (%.2f GB)\n", physmem,
        (double)physmem * sysconf(_SC_PAGE_SIZE) / (1ULL << 30));

    (void) snprintf(hw_serial, sizeof (hw_serial), "%ld",
        (mode & FWRITE) ? gethostid() : 0);

    VERIFY((random_fd = open("/dev/random", O_RDONLY)) != -1);
    VERIFY((urandom_fd = open("/dev/urandom", O_RDONLY)) != -1);

    system_taskq_init();

    mutex_init(&cpu_lock, NULL, MUTEX_DEFAULT, NULL);

    spa_init(mode);

    tsd_create(&rrw_tsd_key, rrw_tsd_destroy);
}

void
kernel_fini(void)
{
    spa_fini();

    system_taskq_fini();

    close(random_fd);
    close(urandom_fd);

    random_fd = -1;
    urandom_fd = -1;
}

int
z_uncompress(void *dst, size_t *dstlen, const void *src, size_t srclen)
{
    int ret;
    uLongf len = *dstlen;

    if ((ret = uncompress(dst, &len, src, srclen)) == Z_OK)
        *dstlen = (size_t)len;

    return (ret);
}

int
z_compress_level(void *dst, size_t *dstlen, const void *src, size_t srclen,
    int level)
{
    int ret;
    uLongf len = *dstlen;

    if ((ret = compress2(dst, &len, src, srclen, level)) == Z_OK)
        *dstlen = (size_t)len;

    return (ret);
}

uid_t
crgetuid(cred_t *cr)
{
    return (0);
}

uid_t
crgetruid(cred_t *cr)
{
    return (0);
}

gid_t
crgetgid(cred_t *cr)
{
    return (0);
}

int
crgetngroups(cred_t *cr)
{
    return (0);
}

gid_t *
crgetgroups(cred_t *cr)
{
    return (NULL);
}

int
zfs_secpolicy_snapshot_perms(const char *name, cred_t *cr)
{
    return (0);
}

int
zfs_secpolicy_rename_perms(const char *from, const char *to, cred_t *cr)
{
    return (0);
}

int
zfs_secpolicy_destroy_perms(const char *name, cred_t *cr)
{
    return (0);
}

ksiddomain_t *
ksid_lookupdomain(const char *dom)
{
    ksiddomain_t *kd;

    kd = umem_zalloc(sizeof (ksiddomain_t), UMEM_NOFAIL);
    kd->kd_name = spa_strdup(dom);
    return (kd);
}

void
ksiddomain_rele(ksiddomain_t *ksid)
{
    spa_strfree(ksid->kd_name);
    umem_free(ksid, sizeof (ksiddomain_t));
}

/*
 * Do not change the length of the returned string; it must be freed
 * with strfree().
 */
char *
kmem_asprintf(const char *fmt, ...)
{
    int size;
    va_list adx;
    char *buf;

    va_start(adx, fmt);
    size = vsnprintf(NULL, 0, fmt, adx) + 1;
    va_end(adx);

    buf = kmem_alloc(size, KM_SLEEP);

    va_start(adx, fmt);
    size = vsnprintf(buf, size, fmt, adx);
    va_end(adx);

    return (buf);
}

/* ARGSUSED */
int
zfs_onexit_fd_hold(int fd, minor_t *minorp)
{
    *minorp = 0;
    return (0);
}

/* ARGSUSED */
void
zfs_onexit_fd_rele(int fd)
{
}

/* ARGSUSED */
int
zfs_onexit_add_cb(minor_t minor, void (*func)(void *), void *data,
    uint64_t *action_handle)
{
    return (0);
}

/* ARGSUSED */
int
zfs_onexit_del_cb(minor_t minor, uint64_t action_handle, boolean_t fire)
{
    return (0);
}

/* ARGSUSED */
int
zfs_onexit_cb_data(minor_t minor, uint64_t action_handle, void **data)
{
    return (0);
}

void
bioinit(buf_t *bp)
{
    bzero(bp, sizeof (buf_t));
}

void
biodone(buf_t *bp)
{
    if (bp->b_iodone != NULL) {
        (*(bp->b_iodone))(bp);
        return;
    }
    ASSERT((bp->b_flags & B_DONE) == 0);
    bp->b_flags |= B_DONE;
}

void
bioerror(buf_t *bp, int error)
{
    ASSERT(bp != NULL);
    ASSERT(error >= 0);

    if (error != 0) {
        bp->b_flags |= B_ERROR;
    } else {
        bp->b_flags &= ~B_ERROR;
    }
    bp->b_error = error;
}


int
geterror(struct buf *bp)
{
    int error = 0;

    if (bp->b_flags & B_ERROR) {
        error = bp->b_error;
        if (!error)
            error = EIO;
    }
    return (error);
}