[mirror_zfs.git] / module / zfs / zfs_vfsops.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, 2014 by Delphix. All rights reserved.
 */

/* Portions Copyright 2010 Robert Milkowski */

#include <sys/types.h>
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/sysmacros.h>
#include <sys/kmem.h>
#include <sys/pathname.h>
#include <sys/vnode.h>
#include <sys/vfs.h>
#include <sys/vfs_opreg.h>
#include <sys/mntent.h>
#include <sys/mount.h>
#include <sys/cmn_err.h>
#include "fs/fs_subr.h"
#include <sys/zfs_znode.h>
#include <sys/zfs_vnops.h>
#include <sys/zfs_dir.h>
#include <sys/zil.h>
#include <sys/fs/zfs.h>
#include <sys/dmu.h>
#include <sys/dsl_prop.h>
#include <sys/dsl_dataset.h>
#include <sys/dsl_deleg.h>
#include <sys/spa.h>
#include <sys/zap.h>
#include <sys/sa.h>
#include <sys/sa_impl.h>
#include <sys/varargs.h>
#include <sys/policy.h>
#include <sys/atomic.h>
#include <sys/mkdev.h>
#include <sys/modctl.h>
#include <sys/refstr.h>
#include <sys/zfs_ioctl.h>
#include <sys/zfs_ctldir.h>
#include <sys/zfs_fuid.h>
#include <sys/bootconf.h>
#include <sys/sunddi.h>
#include <sys/dnlc.h>
#include <sys/dmu_objset.h>
#include <sys/spa_boot.h>
#include <sys/zpl.h>
#include "zfs_comutil.h"

/*ARGSUSED*/
int
zfs_sync(struct super_block *sb, int wait, cred_t *cr)
{
        zfs_sb_t *zsb = sb->s_fs_info;

        /*
         * Data integrity is job one.  We don't want a compromised kernel
         * writing to the storage pool, so we never sync during panic.
         */
        if (unlikely(oops_in_progress))
                return (0);

        /*
         * Semantically, the only requirement is that the sync be initiated.
         * The DMU syncs out txgs frequently, so there's nothing to do.
         */
        if (!wait)
                return (0);

        if (zsb != NULL) {
                /*
                 * Sync a specific filesystem.
                 */
                dsl_pool_t *dp;

                ZFS_ENTER(zsb);
                dp = dmu_objset_pool(zsb->z_os);

                /*
                 * If the system is shutting down, then skip any
                 * filesystems which may exist on a suspended pool.
                 */
                if (spa_suspended(dp->dp_spa)) {
                        ZFS_EXIT(zsb);
                        return (0);
                }

                if (zsb->z_log != NULL)
                        zil_commit(zsb->z_log, 0);

                ZFS_EXIT(zsb);
        } else {
                /*
                 * Sync all ZFS filesystems.  This is what happens when you
                 * run sync(1M).  Unlike other filesystems, ZFS honors the
                 * request by waiting for all pools to commit all dirty data.
                 */
                spa_sync_allpools();
        }

        return (0);
}
EXPORT_SYMBOL(zfs_sync);

boolean_t
zfs_is_readonly(zfs_sb_t *zsb)
{
        return (!!(zsb->z_sb->s_flags & MS_RDONLY));
}
EXPORT_SYMBOL(zfs_is_readonly);

static void
atime_changed_cb(void *arg, uint64_t newval)
{
        ((zfs_sb_t *)arg)->z_atime = newval;
}

static void
relatime_changed_cb(void *arg, uint64_t newval)
{
        ((zfs_sb_t *)arg)->z_relatime = newval;
}

static void
xattr_changed_cb(void *arg, uint64_t newval)
{
        zfs_sb_t *zsb = arg;

        if (newval == ZFS_XATTR_OFF) {
                zsb->z_flags &= ~ZSB_XATTR;
        } else {
                zsb->z_flags |= ZSB_XATTR;

                if (newval == ZFS_XATTR_SA)
                        zsb->z_xattr_sa = B_TRUE;
                else
                        zsb->z_xattr_sa = B_FALSE;
        }
}

static void
acltype_changed_cb(void *arg, uint64_t newval)
{
        zfs_sb_t *zsb = arg;

        switch (newval) {
        case ZFS_ACLTYPE_OFF:
                zsb->z_acl_type = ZFS_ACLTYPE_OFF;
                zsb->z_sb->s_flags &= ~MS_POSIXACL;
                break;
        case ZFS_ACLTYPE_POSIXACL:
#ifdef CONFIG_FS_POSIX_ACL
                zsb->z_acl_type = ZFS_ACLTYPE_POSIXACL;
                zsb->z_sb->s_flags |= MS_POSIXACL;
#else
                zsb->z_acl_type = ZFS_ACLTYPE_OFF;
                zsb->z_sb->s_flags &= ~MS_POSIXACL;
#endif /* CONFIG_FS_POSIX_ACL */
                break;
        default:
                break;
        }
}

static void
blksz_changed_cb(void *arg, uint64_t newval)
{
        zfs_sb_t *zsb = arg;
        ASSERT3U(newval, <=, spa_maxblocksize(dmu_objset_spa(zsb->z_os)));
        ASSERT3U(newval, >=, SPA_MINBLOCKSIZE);
        ASSERT(ISP2(newval));

        zsb->z_max_blksz = newval;
}

static void
readonly_changed_cb(void *arg, uint64_t newval)
{
        zfs_sb_t *zsb = arg;
        struct super_block *sb = zsb->z_sb;

        if (sb == NULL)
                return;

        if (newval)
                sb->s_flags |= MS_RDONLY;
        else
                sb->s_flags &= ~MS_RDONLY;
}

static void
devices_changed_cb(void *arg, uint64_t newval)
{
}

static void
setuid_changed_cb(void *arg, uint64_t newval)
{
}

static void
exec_changed_cb(void *arg, uint64_t newval)
{
}

static void
nbmand_changed_cb(void *arg, uint64_t newval)
{
        zfs_sb_t *zsb = arg;
        struct super_block *sb = zsb->z_sb;

        if (sb == NULL)
                return;

        if (newval == TRUE)
                sb->s_flags |= MS_MANDLOCK;
        else
                sb->s_flags &= ~MS_MANDLOCK;
}

static void
snapdir_changed_cb(void *arg, uint64_t newval)
{
        ((zfs_sb_t *)arg)->z_show_ctldir = newval;
}

static void
vscan_changed_cb(void *arg, uint64_t newval)
{
        ((zfs_sb_t *)arg)->z_vscan = newval;
}

static void
acl_inherit_changed_cb(void *arg, uint64_t newval)
{
        ((zfs_sb_t *)arg)->z_acl_inherit = newval;
}

int
zfs_register_callbacks(zfs_sb_t *zsb)
{
        struct dsl_dataset *ds = NULL;
        objset_t *os = zsb->z_os;
        zfs_mntopts_t *zmo = zsb->z_mntopts;
        int error = 0;

        ASSERT(zsb);
        ASSERT(zmo);

        /*
         * The act of registering our callbacks will destroy any mount
         * options we may have.  In order to enable temporary overrides
         * of mount options, we stash away the current values and
         * restore them after we register the callbacks.
         */
        if (zfs_is_readonly(zsb) || !spa_writeable(dmu_objset_spa(os))) {
                zmo->z_do_readonly = B_TRUE;
                zmo->z_readonly = B_TRUE;
        }

        /*
         * Register property callbacks.
         *
         * It would probably be fine to just check for i/o error from
         * the first prop_register(), but I guess I like to go
         * overboard...
         */
        ds = dmu_objset_ds(os);
        dsl_pool_config_enter(dmu_objset_pool(os), FTAG);
        error = dsl_prop_register(ds,
            zfs_prop_to_name(ZFS_PROP_ATIME), atime_changed_cb, zsb);
        error = error ? error : dsl_prop_register(ds,
            zfs_prop_to_name(ZFS_PROP_RELATIME), relatime_changed_cb, zsb);
        error = error ? error : dsl_prop_register(ds,
            zfs_prop_to_name(ZFS_PROP_XATTR), xattr_changed_cb, zsb);
        error = error ? error : dsl_prop_register(ds,
            zfs_prop_to_name(ZFS_PROP_RECORDSIZE), blksz_changed_cb, zsb);
        error = error ? error : dsl_prop_register(ds,
            zfs_prop_to_name(ZFS_PROP_READONLY), readonly_changed_cb, zsb);
        error = error ? error : dsl_prop_register(ds,
            zfs_prop_to_name(ZFS_PROP_DEVICES), devices_changed_cb, zsb);
        error = error ? error : dsl_prop_register(ds,
            zfs_prop_to_name(ZFS_PROP_SETUID), setuid_changed_cb, zsb);
        error = error ? error : dsl_prop_register(ds,
            zfs_prop_to_name(ZFS_PROP_EXEC), exec_changed_cb, zsb);
        error = error ? error : dsl_prop_register(ds,
            zfs_prop_to_name(ZFS_PROP_SNAPDIR), snapdir_changed_cb, zsb);
        error = error ? error : dsl_prop_register(ds,
            zfs_prop_to_name(ZFS_PROP_ACLTYPE), acltype_changed_cb, zsb);
        error = error ? error : dsl_prop_register(ds,
            zfs_prop_to_name(ZFS_PROP_ACLINHERIT), acl_inherit_changed_cb, zsb);
        error = error ? error : dsl_prop_register(ds,
            zfs_prop_to_name(ZFS_PROP_VSCAN), vscan_changed_cb, zsb);
        error = error ? error : dsl_prop_register(ds,
            zfs_prop_to_name(ZFS_PROP_NBMAND), nbmand_changed_cb, zsb);
        dsl_pool_config_exit(dmu_objset_pool(os), FTAG);
        if (error)
                goto unregister;

        /*
         * Invoke our callbacks to restore temporary mount options.
         */
        if (zmo->z_do_readonly)
                readonly_changed_cb(zsb, zmo->z_readonly);
        if (zmo->z_do_setuid)
                setuid_changed_cb(zsb, zmo->z_setuid);
        if (zmo->z_do_exec)
                exec_changed_cb(zsb, zmo->z_exec);
        if (zmo->z_do_devices)
                devices_changed_cb(zsb, zmo->z_devices);
        if (zmo->z_do_xattr)
                xattr_changed_cb(zsb, zmo->z_xattr);
        if (zmo->z_do_atime)
                atime_changed_cb(zsb, zmo->z_atime);
        if (zmo->z_do_relatime)
                relatime_changed_cb(zsb, zmo->z_relatime);
        if (zmo->z_do_nbmand)
                nbmand_changed_cb(zsb, zmo->z_nbmand);

        return (0);

unregister:
        dsl_prop_unregister_all(ds, zsb);
        return (error);
}
EXPORT_SYMBOL(zfs_register_callbacks);

static int
zfs_space_delta_cb(dmu_object_type_t bonustype, void *data,
    uint64_t *userp, uint64_t *groupp)
{
        /*
         * Is it a valid type of object to track?
         */
        if (bonustype != DMU_OT_ZNODE && bonustype != DMU_OT_SA)
                return (SET_ERROR(ENOENT));

        /*
         * If we have a NULL data pointer
         * then assume the id's aren't changing and
         * return EEXIST to the dmu to let it know to
         * use the same ids
         */
        if (data == NULL)
                return (SET_ERROR(EEXIST));

        if (bonustype == DMU_OT_ZNODE) {
                znode_phys_t *znp = data;
                *userp = znp->zp_uid;
                *groupp = znp->zp_gid;
        } else {
                int hdrsize;
                sa_hdr_phys_t *sap = data;
                sa_hdr_phys_t sa = *sap;
                boolean_t swap = B_FALSE;

                ASSERT(bonustype == DMU_OT_SA);

                if (sa.sa_magic == 0) {
                        /*
                         * This should only happen for newly created
                         * files that haven't had the znode data filled
                         * in yet.
                         */
                        *userp = 0;
                        *groupp = 0;
                        return (0);
                }
                if (sa.sa_magic == BSWAP_32(SA_MAGIC)) {
                        sa.sa_magic = SA_MAGIC;
                        sa.sa_layout_info = BSWAP_16(sa.sa_layout_info);
                        swap = B_TRUE;
                } else {
                        VERIFY3U(sa.sa_magic, ==, SA_MAGIC);
                }

                hdrsize = sa_hdrsize(&sa);
                VERIFY3U(hdrsize, >=, sizeof (sa_hdr_phys_t));
                *userp = *((uint64_t *)((uintptr_t)data + hdrsize +
                    SA_UID_OFFSET));
                *groupp = *((uint64_t *)((uintptr_t)data + hdrsize +
                    SA_GID_OFFSET));
                if (swap) {
                        *userp = BSWAP_64(*userp);
                        *groupp = BSWAP_64(*groupp);
                }
        }
        return (0);
}

static void
fuidstr_to_sid(zfs_sb_t *zsb, const char *fuidstr,
    char *domainbuf, int buflen, uid_t *ridp)
{
        uint64_t fuid;
        const char *domain;

        fuid = strtonum(fuidstr, NULL);

        domain = zfs_fuid_find_by_idx(zsb, FUID_INDEX(fuid));
        if (domain)
                (void) strlcpy(domainbuf, domain, buflen);
        else
                domainbuf[0] = '\0';
        *ridp = FUID_RID(fuid);
}

static uint64_t
zfs_userquota_prop_to_obj(zfs_sb_t *zsb, zfs_userquota_prop_t type)
{
        switch (type) {
        case ZFS_PROP_USERUSED:
                return (DMU_USERUSED_OBJECT);
        case ZFS_PROP_GROUPUSED:
                return (DMU_GROUPUSED_OBJECT);
        case ZFS_PROP_USERQUOTA:
                return (zsb->z_userquota_obj);
        case ZFS_PROP_GROUPQUOTA:
                return (zsb->z_groupquota_obj);
        default:
                return (SET_ERROR(ENOTSUP));
        }
        return (0);
}

int
zfs_userspace_many(zfs_sb_t *zsb, zfs_userquota_prop_t type,
    uint64_t *cookiep, void *vbuf, uint64_t *bufsizep)
{
        int error;
        zap_cursor_t zc;
        zap_attribute_t za;
        zfs_useracct_t *buf = vbuf;
        uint64_t obj;

        if (!dmu_objset_userspace_present(zsb->z_os))
                return (SET_ERROR(ENOTSUP));

        obj = zfs_userquota_prop_to_obj(zsb, type);
        if (obj == 0) {
                *bufsizep = 0;
                return (0);
        }

        for (zap_cursor_init_serialized(&zc, zsb->z_os, obj, *cookiep);
            (error = zap_cursor_retrieve(&zc, &za)) == 0;
            zap_cursor_advance(&zc)) {
                if ((uintptr_t)buf - (uintptr_t)vbuf + sizeof (zfs_useracct_t) >
                    *bufsizep)
                        break;

                fuidstr_to_sid(zsb, za.za_name,
                    buf->zu_domain, sizeof (buf->zu_domain), &buf->zu_rid);

                buf->zu_space = za.za_first_integer;
                buf++;
        }
        if (error == ENOENT)
                error = 0;

        ASSERT3U((uintptr_t)buf - (uintptr_t)vbuf, <=, *bufsizep);
        *bufsizep = (uintptr_t)buf - (uintptr_t)vbuf;
        *cookiep = zap_cursor_serialize(&zc);
        zap_cursor_fini(&zc);
        return (error);
}
EXPORT_SYMBOL(zfs_userspace_many);

/*
 * buf must be big enough (eg, 32 bytes)
 */
static int
id_to_fuidstr(zfs_sb_t *zsb, const char *domain, uid_t rid,
    char *buf, boolean_t addok)
{
        uint64_t fuid;
        int domainid = 0;

        if (domain && domain[0]) {
                domainid = zfs_fuid_find_by_domain(zsb, domain, NULL, addok);
                if (domainid == -1)
                        return (SET_ERROR(ENOENT));
        }
        fuid = FUID_ENCODE(domainid, rid);
        (void) sprintf(buf, "%llx", (longlong_t)fuid);
        return (0);
}

int
zfs_userspace_one(zfs_sb_t *zsb, zfs_userquota_prop_t type,
    const char *domain, uint64_t rid, uint64_t *valp)
{
        char buf[32];
        int err;
        uint64_t obj;

        *valp = 0;

        if (!dmu_objset_userspace_present(zsb->z_os))
                return (SET_ERROR(ENOTSUP));

        obj = zfs_userquota_prop_to_obj(zsb, type);
        if (obj == 0)
                return (0);

        err = id_to_fuidstr(zsb, domain, rid, buf, B_FALSE);
        if (err)
                return (err);

        err = zap_lookup(zsb->z_os, obj, buf, 8, 1, valp);
        if (err == ENOENT)
                err = 0;
        return (err);
}
EXPORT_SYMBOL(zfs_userspace_one);

int
zfs_set_userquota(zfs_sb_t *zsb, zfs_userquota_prop_t type,
    const char *domain, uint64_t rid, uint64_t quota)
{
        char buf[32];
        int err;
        dmu_tx_t *tx;
        uint64_t *objp;
        boolean_t fuid_dirtied;

        if (type != ZFS_PROP_USERQUOTA && type != ZFS_PROP_GROUPQUOTA)
                return (SET_ERROR(EINVAL));

        if (zsb->z_version < ZPL_VERSION_USERSPACE)
                return (SET_ERROR(ENOTSUP));

        objp = (type == ZFS_PROP_USERQUOTA) ? &zsb->z_userquota_obj :
            &zsb->z_groupquota_obj;

        err = id_to_fuidstr(zsb, domain, rid, buf, B_TRUE);
        if (err)
                return (err);
        fuid_dirtied = zsb->z_fuid_dirty;

        tx = dmu_tx_create(zsb->z_os);
        dmu_tx_hold_zap(tx, *objp ? *objp : DMU_NEW_OBJECT, B_TRUE, NULL);
        if (*objp == 0) {
                dmu_tx_hold_zap(tx, MASTER_NODE_OBJ, B_TRUE,
                    zfs_userquota_prop_prefixes[type]);
        }
        if (fuid_dirtied)
                zfs_fuid_txhold(zsb, tx);
        err = dmu_tx_assign(tx, TXG_WAIT);
        if (err) {
                dmu_tx_abort(tx);
                return (err);
        }

        mutex_enter(&zsb->z_lock);
        if (*objp == 0) {
                *objp = zap_create(zsb->z_os, DMU_OT_USERGROUP_QUOTA,
                    DMU_OT_NONE, 0, tx);
                VERIFY(0 == zap_add(zsb->z_os, MASTER_NODE_OBJ,
                    zfs_userquota_prop_prefixes[type], 8, 1, objp, tx));
        }
        mutex_exit(&zsb->z_lock);

        if (quota == 0) {
                err = zap_remove(zsb->z_os, *objp, buf, tx);
                if (err == ENOENT)
                        err = 0;
        } else {
                err = zap_update(zsb->z_os, *objp, buf, 8, 1, &quota, tx);
        }
        ASSERT(err == 0);
        if (fuid_dirtied)
                zfs_fuid_sync(zsb, tx);
        dmu_tx_commit(tx);
        return (err);
}
EXPORT_SYMBOL(zfs_set_userquota);

boolean_t
zfs_fuid_overquota(zfs_sb_t *zsb, boolean_t isgroup, uint64_t fuid)
{
        char buf[32];
        uint64_t used, quota, usedobj, quotaobj;
        int err;

        usedobj = isgroup ? DMU_GROUPUSED_OBJECT : DMU_USERUSED_OBJECT;
        quotaobj = isgroup ? zsb->z_groupquota_obj : zsb->z_userquota_obj;

        if (quotaobj == 0 || zsb->z_replay)
                return (B_FALSE);

        (void) sprintf(buf, "%llx", (longlong_t)fuid);
        err = zap_lookup(zsb->z_os, quotaobj, buf, 8, 1, &quota);
        if (err != 0)
                return (B_FALSE);

        err = zap_lookup(zsb->z_os, usedobj, buf, 8, 1, &used);
        if (err != 0)
                return (B_FALSE);
        return (used >= quota);
}
EXPORT_SYMBOL(zfs_fuid_overquota);

boolean_t
zfs_owner_overquota(zfs_sb_t *zsb, znode_t *zp, boolean_t isgroup)
{
        uint64_t fuid;
        uint64_t quotaobj;
        struct inode *ip = ZTOI(zp);

        quotaobj = isgroup ? zsb->z_groupquota_obj : zsb->z_userquota_obj;

        fuid = isgroup ? KGID_TO_SGID(ip->i_gid) : KUID_TO_SUID(ip->i_uid);

        if (quotaobj == 0 || zsb->z_replay)
                return (B_FALSE);

        return (zfs_fuid_overquota(zsb, isgroup, fuid));
}
EXPORT_SYMBOL(zfs_owner_overquota);

zfs_mntopts_t *
zfs_mntopts_alloc(void)
{
        return (kmem_zalloc(sizeof (zfs_mntopts_t), KM_SLEEP));
}

void
zfs_mntopts_free(zfs_mntopts_t *zmo)
{
        if (zmo->z_osname)
                strfree(zmo->z_osname);

        if (zmo->z_mntpoint)
                strfree(zmo->z_mntpoint);

        kmem_free(zmo, sizeof (zfs_mntopts_t));
}

int
zfs_sb_create(const char *osname, zfs_mntopts_t *zmo, zfs_sb_t **zsbp)
{
        objset_t *os;
        zfs_sb_t *zsb;
        uint64_t zval;
        int i, size, error;
        uint64_t sa_obj;

        zsb = kmem_zalloc(sizeof (zfs_sb_t), KM_SLEEP);

        /*
         * We claim to always be readonly so we can open snapshots;
         * other ZPL code will prevent us from writing to snapshots.
         */
        error = dmu_objset_own(osname, DMU_OST_ZFS, B_TRUE, zsb, &os);
        if (error) {
                kmem_free(zsb, sizeof (zfs_sb_t));
                return (error);
        }

        /*
         * Optional temporary mount options, free'd in zfs_sb_free().
         */
        zsb->z_mntopts = (zmo ? zmo : zfs_mntopts_alloc());

        /*
         * Initialize the zfs-specific filesystem structure.
         * Should probably make this a kmem cache, shuffle fields.
         */
        zsb->z_sb = NULL;
        zsb->z_parent = zsb;
        zsb->z_max_blksz = SPA_OLD_MAXBLOCKSIZE;
        zsb->z_show_ctldir = ZFS_SNAPDIR_VISIBLE;
        zsb->z_os = os;

        error = zfs_get_zplprop(os, ZFS_PROP_VERSION, &zsb->z_version);
        if (error) {
                goto out;
        } else if (zsb->z_version > ZPL_VERSION) {
                error = SET_ERROR(ENOTSUP);
                goto out;
        }
        if ((error = zfs_get_zplprop(os, ZFS_PROP_NORMALIZE, &zval)) != 0)
                goto out;
        zsb->z_norm = (int)zval;

        if ((error = zfs_get_zplprop(os, ZFS_PROP_UTF8ONLY, &zval)) != 0)
                goto out;
        zsb->z_utf8 = (zval != 0);

        if ((error = zfs_get_zplprop(os, ZFS_PROP_CASE, &zval)) != 0)
                goto out;
        zsb->z_case = (uint_t)zval;

        if ((error = zfs_get_zplprop(os, ZFS_PROP_ACLTYPE, &zval)) != 0)
                goto out;
        zsb->z_acl_type = (uint_t)zval;

        /*
         * Fold case on file systems that are always or sometimes case
         * insensitive.
         */
        if (zsb->z_case == ZFS_CASE_INSENSITIVE ||
            zsb->z_case == ZFS_CASE_MIXED)
                zsb->z_norm |= U8_TEXTPREP_TOUPPER;

        zsb->z_use_fuids = USE_FUIDS(zsb->z_version, zsb->z_os);
        zsb->z_use_sa = USE_SA(zsb->z_version, zsb->z_os);

        if (zsb->z_use_sa) {
                /* should either have both of these objects or none */
                error = zap_lookup(os, MASTER_NODE_OBJ, ZFS_SA_ATTRS, 8, 1,
                    &sa_obj);
                if (error)
                        goto out;

                error = zfs_get_zplprop(os, ZFS_PROP_XATTR, &zval);
                if ((error == 0) && (zval == ZFS_XATTR_SA))
                        zsb->z_xattr_sa = B_TRUE;
        } else {
                /*
                 * Pre SA versions file systems should never touch
                 * either the attribute registration or layout objects.
                 */
                sa_obj = 0;
        }

        error = sa_setup(os, sa_obj, zfs_attr_table, ZPL_END,
            &zsb->z_attr_table);
        if (error)
                goto out;

        if (zsb->z_version >= ZPL_VERSION_SA)
                sa_register_update_callback(os, zfs_sa_upgrade);

        error = zap_lookup(os, MASTER_NODE_OBJ, ZFS_ROOT_OBJ, 8, 1,
            &zsb->z_root);
        if (error)
                goto out;
        ASSERT(zsb->z_root != 0);

        error = zap_lookup(os, MASTER_NODE_OBJ, ZFS_UNLINKED_SET, 8, 1,
            &zsb->z_unlinkedobj);
        if (error)
                goto out;

        error = zap_lookup(os, MASTER_NODE_OBJ,
            zfs_userquota_prop_prefixes[ZFS_PROP_USERQUOTA],
            8, 1, &zsb->z_userquota_obj);
        if (error && error != ENOENT)
                goto out;

        error = zap_lookup(os, MASTER_NODE_OBJ,
            zfs_userquota_prop_prefixes[ZFS_PROP_GROUPQUOTA],
            8, 1, &zsb->z_groupquota_obj);
        if (error && error != ENOENT)
                goto out;

        error = zap_lookup(os, MASTER_NODE_OBJ, ZFS_FUID_TABLES, 8, 1,
            &zsb->z_fuid_obj);
        if (error && error != ENOENT)
                goto out;

        error = zap_lookup(os, MASTER_NODE_OBJ, ZFS_SHARES_DIR, 8, 1,
            &zsb->z_shares_dir);
        if (error && error != ENOENT)
                goto out;

        mutex_init(&zsb->z_znodes_lock, NULL, MUTEX_DEFAULT, NULL);
        mutex_init(&zsb->z_lock, NULL, MUTEX_DEFAULT, NULL);
        list_create(&zsb->z_all_znodes, sizeof (znode_t),
            offsetof(znode_t, z_link_node));
        rrm_init(&zsb->z_teardown_lock, B_FALSE);
        rw_init(&zsb->z_teardown_inactive_lock, NULL, RW_DEFAULT, NULL);
        rw_init(&zsb->z_fuid_lock, NULL, RW_DEFAULT, NULL);

        size = MIN(1 << (highbit64(zfs_object_mutex_size)-1), ZFS_OBJ_MTX_MAX);
        zsb->z_hold_size = size;
        zsb->z_hold_trees = vmem_zalloc(sizeof (avl_tree_t) * size, KM_SLEEP);
        zsb->z_hold_locks = vmem_zalloc(sizeof (kmutex_t) * size, KM_SLEEP);
        for (i = 0; i != size; i++) {
                avl_create(&zsb->z_hold_trees[i], zfs_znode_hold_compare,
                    sizeof (znode_hold_t), offsetof(znode_hold_t, zh_node));
                mutex_init(&zsb->z_hold_locks[i], NULL, MUTEX_DEFAULT, NULL);
        }

        *zsbp = zsb;
        return (0);

out:
        dmu_objset_disown(os, zsb);
        *zsbp = NULL;

        kmem_free(zsb, sizeof (zfs_sb_t));
        return (error);
}
EXPORT_SYMBOL(zfs_sb_create);

int
zfs_sb_setup(zfs_sb_t *zsb, boolean_t mounting)
{
        int error;

        error = zfs_register_callbacks(zsb);
        if (error)
                return (error);

        /*
         * Set the objset user_ptr to track its zsb.
         */
        mutex_enter(&zsb->z_os->os_user_ptr_lock);
        dmu_objset_set_user(zsb->z_os, zsb);
        mutex_exit(&zsb->z_os->os_user_ptr_lock);

        zsb->z_log = zil_open(zsb->z_os, zfs_get_data);

        /*
         * If we are not mounting (ie: online recv), then we don't
         * have to worry about replaying the log as we blocked all
         * operations out since we closed the ZIL.
         */
        if (mounting) {
                boolean_t readonly;

                /*
                 * During replay we remove the read only flag to
                 * allow replays to succeed.
                 */
                readonly = zfs_is_readonly(zsb);
                if (readonly != 0)
                        readonly_changed_cb(zsb, B_FALSE);
                else
                        zfs_unlinked_drain(zsb);

                /*
                 * Parse and replay the intent log.
                 *
                 * Because of ziltest, this must be done after
                 * zfs_unlinked_drain().  (Further note: ziltest
                 * doesn't use readonly mounts, where
                 * zfs_unlinked_drain() isn't called.)  This is because
                 * ziltest causes spa_sync() to think it's committed,
                 * but actually it is not, so the intent log contains
                 * many txg's worth of changes.
                 *
                 * In particular, if object N is in the unlinked set in
                 * the last txg to actually sync, then it could be
                 * actually freed in a later txg and then reallocated
                 * in a yet later txg.  This would write a "create
                 * object N" record to the intent log.  Normally, this
                 * would be fine because the spa_sync() would have
                 * written out the fact that object N is free, before
                 * we could write the "create object N" intent log
                 * record.
                 *
                 * But when we are in ziltest mode, we advance the "open
                 * txg" without actually spa_sync()-ing the changes to
                 * disk.  So we would see that object N is still
                 * allocated and in the unlinked set, and there is an
                 * intent log record saying to allocate it.
                 */
                if (spa_writeable(dmu_objset_spa(zsb->z_os))) {
                        if (zil_replay_disable) {
                                zil_destroy(zsb->z_log, B_FALSE);
                        } else {
                                zsb->z_replay = B_TRUE;
                                zil_replay(zsb->z_os, zsb,
                                    zfs_replay_vector);
                                zsb->z_replay = B_FALSE;
                        }
                }

                /* restore readonly bit */
                if (readonly != 0)
                        readonly_changed_cb(zsb, B_TRUE);
        }

        return (0);
}
EXPORT_SYMBOL(zfs_sb_setup);

void
zfs_sb_free(zfs_sb_t *zsb)
{
        int i, size = zsb->z_hold_size;

        zfs_fuid_destroy(zsb);

        mutex_destroy(&zsb->z_znodes_lock);
        mutex_destroy(&zsb->z_lock);
        list_destroy(&zsb->z_all_znodes);
        rrm_destroy(&zsb->z_teardown_lock);
        rw_destroy(&zsb->z_teardown_inactive_lock);
        rw_destroy(&zsb->z_fuid_lock);
        for (i = 0; i != size; i++) {
                avl_destroy(&zsb->z_hold_trees[i]);
                mutex_destroy(&zsb->z_hold_locks[i]);
        }
        vmem_free(zsb->z_hold_trees, sizeof (avl_tree_t) * size);
        vmem_free(zsb->z_hold_locks, sizeof (kmutex_t) * size);
        zfs_mntopts_free(zsb->z_mntopts);
        kmem_free(zsb, sizeof (zfs_sb_t));
}
EXPORT_SYMBOL(zfs_sb_free);

static void
zfs_set_fuid_feature(zfs_sb_t *zsb)
{
        zsb->z_use_fuids = USE_FUIDS(zsb->z_version, zsb->z_os);
        zsb->z_use_sa = USE_SA(zsb->z_version, zsb->z_os);
}

void
zfs_unregister_callbacks(zfs_sb_t *zsb)
{
        objset_t *os = zsb->z_os;

        if (!dmu_objset_is_snapshot(os))
                dsl_prop_unregister_all(dmu_objset_ds(os), zsb);
}
EXPORT_SYMBOL(zfs_unregister_callbacks);

#ifdef HAVE_MLSLABEL
/*
 * Check that the hex label string is appropriate for the dataset being
 * mounted into the global_zone proper.
 *
 * Return an error if the hex label string is not default or
 * admin_low/admin_high.  For admin_low labels, the corresponding
 * dataset must be readonly.
 */
int
zfs_check_global_label(const char *dsname, const char *hexsl)
{
        if (strcasecmp(hexsl, ZFS_MLSLABEL_DEFAULT) == 0)
                return (0);
        if (strcasecmp(hexsl, ADMIN_HIGH) == 0)
                return (0);
        if (strcasecmp(hexsl, ADMIN_LOW) == 0) {
                /* must be readonly */
                uint64_t rdonly;

                if (dsl_prop_get_integer(dsname,
                    zfs_prop_to_name(ZFS_PROP_READONLY), &rdonly, NULL))
                        return (SET_ERROR(EACCES));
                return (rdonly ? 0 : EACCES);
        }
        return (SET_ERROR(EACCES));
}
EXPORT_SYMBOL(zfs_check_global_label);
#endif /* HAVE_MLSLABEL */

int
zfs_statvfs(struct dentry *dentry, struct kstatfs *statp)
{
        zfs_sb_t *zsb = dentry->d_sb->s_fs_info;
        uint64_t refdbytes, availbytes, usedobjs, availobjs;
        uint64_t fsid;
        uint32_t bshift;

        ZFS_ENTER(zsb);

        dmu_objset_space(zsb->z_os,
            &refdbytes, &availbytes, &usedobjs, &availobjs);

        fsid = dmu_objset_fsid_guid(zsb->z_os);
        /*
         * The underlying storage pool actually uses multiple block
         * size.  Under Solaris frsize (fragment size) is reported as
         * the smallest block size we support, and bsize (block size)
         * as the filesystem's maximum block size.  Unfortunately,
         * under Linux the fragment size and block size are often used
         * interchangeably.  Thus we are forced to report both of them
         * as the filesystem's maximum block size.
         */
        statp->f_frsize = zsb->z_max_blksz;
        statp->f_bsize = zsb->z_max_blksz;
        bshift = fls(statp->f_bsize) - 1;

        /*
         * The following report "total" blocks of various kinds in
         * the file system, but reported in terms of f_bsize - the
         * "preferred" size.
         */

        statp->f_blocks = (refdbytes + availbytes) >> bshift;
        statp->f_bfree = availbytes >> bshift;
        statp->f_bavail = statp->f_bfree; /* no root reservation */

        /*
         * statvfs() should really be called statufs(), because it assumes
         * static metadata.  ZFS doesn't preallocate files, so the best
         * we can do is report the max that could possibly fit in f_files,
         * and that minus the number actually used in f_ffree.
         * For f_ffree, report the smaller of the number of object available
         * and the number of blocks (each object will take at least a block).
         */
        statp->f_ffree = MIN(availobjs, availbytes >> DNODE_SHIFT);
        statp->f_files = statp->f_ffree + usedobjs;
        statp->f_fsid.val[0] = (uint32_t)fsid;
        statp->f_fsid.val[1] = (uint32_t)(fsid >> 32);
        statp->f_type = ZFS_SUPER_MAGIC;
        statp->f_namelen = MAXNAMELEN - 1;

        /*
         * We have all of 40 characters to stuff a string here.
         * Is there anything useful we could/should provide?
         */
        bzero(statp->f_spare, sizeof (statp->f_spare));

        ZFS_EXIT(zsb);
        return (0);
}
EXPORT_SYMBOL(zfs_statvfs);

int
zfs_root(zfs_sb_t *zsb, struct inode **ipp)
{
        znode_t *rootzp;
        int error;

        ZFS_ENTER(zsb);

        error = zfs_zget(zsb, zsb->z_root, &rootzp);
        if (error == 0)
                *ipp = ZTOI(rootzp);

        ZFS_EXIT(zsb);
        return (error);
}
EXPORT_SYMBOL(zfs_root);

#ifdef HAVE_D_PRUNE_ALIASES
/*
 * Linux kernels older than 3.1 do not support a per-filesystem shrinker.
 * To accommodate this we must improvise and manually walk the list of znodes
 * attempting to prune dentries in order to be able to drop the inodes.
 *
 * To avoid scanning the same znodes multiple times they are always rotated
 * to the end of the z_all_znodes list.  New znodes are inserted at the
 * end of the list so we're always scanning the oldest znodes first.
 */
static int
zfs_sb_prune_aliases(zfs_sb_t *zsb, unsigned long nr_to_scan)
{
        znode_t **zp_array, *zp;
        int max_array = MIN(nr_to_scan, PAGE_SIZE * 8 / sizeof (znode_t *));
        int objects = 0;
        int i = 0, j = 0;

        zp_array = kmem_zalloc(max_array * sizeof (znode_t *), KM_SLEEP);

        mutex_enter(&zsb->z_znodes_lock);
        while ((zp = list_head(&zsb->z_all_znodes)) != NULL) {

                if ((i++ > nr_to_scan) || (j >= max_array))
                        break;

                ASSERT(list_link_active(&zp->z_link_node));
                list_remove(&zsb->z_all_znodes, zp);
                list_insert_tail(&zsb->z_all_znodes, zp);

                /* Skip active znodes and .zfs entries */
                if (MUTEX_HELD(&zp->z_lock) || zp->z_is_ctldir)
                        continue;

                if (igrab(ZTOI(zp)) == NULL)
                        continue;

                zp_array[j] = zp;
                j++;
        }
        mutex_exit(&zsb->z_znodes_lock);

        for (i = 0; i < j; i++) {
                zp = zp_array[i];

                ASSERT3P(zp, !=, NULL);
                d_prune_aliases(ZTOI(zp));

                if (atomic_read(&ZTOI(zp)->i_count) == 1)
                        objects++;

                iput(ZTOI(zp));
        }

        kmem_free(zp_array, max_array * sizeof (znode_t *));

        return (objects);
}
#endif /* HAVE_D_PRUNE_ALIASES */

/*
 * The ARC has requested that the filesystem drop entries from the dentry
 * and inode caches.  This can occur when the ARC needs to free meta data
 * blocks but can't because they are all pinned by entries in these caches.
 */
int
zfs_sb_prune(struct super_block *sb, unsigned long nr_to_scan, int *objects)
{
        zfs_sb_t *zsb = sb->s_fs_info;
        int error = 0;
#if defined(HAVE_SHRINK) || defined(HAVE_SPLIT_SHRINKER_CALLBACK)
        struct shrinker *shrinker = &sb->s_shrink;
        struct shrink_control sc = {
                .nr_to_scan = nr_to_scan,
                .gfp_mask = GFP_KERNEL,
        };
#endif

        ZFS_ENTER(zsb);

#if defined(HAVE_SPLIT_SHRINKER_CALLBACK) && \
        defined(SHRINK_CONTROL_HAS_NID) && \
        defined(SHRINKER_NUMA_AWARE)
        if (sb->s_shrink.flags & SHRINKER_NUMA_AWARE) {
                *objects = 0;
                for_each_online_node(sc.nid)
                        *objects += (*shrinker->scan_objects)(shrinker, &sc);
        } else {
                        *objects = (*shrinker->scan_objects)(shrinker, &sc);
        }

#elif defined(HAVE_SPLIT_SHRINKER_CALLBACK)
        *objects = (*shrinker->scan_objects)(shrinker, &sc);
#elif defined(HAVE_SHRINK)
        *objects = (*shrinker->shrink)(shrinker, &sc);
#elif defined(HAVE_D_PRUNE_ALIASES)
#define D_PRUNE_ALIASES_IS_DEFAULT
        *objects = zfs_sb_prune_aliases(zsb, nr_to_scan);
#else
#error "No available dentry and inode cache pruning mechanism."
#endif

#if defined(HAVE_D_PRUNE_ALIASES) && !defined(D_PRUNE_ALIASES_IS_DEFAULT)
#undef  D_PRUNE_ALIASES_IS_DEFAULT
        /*
         * Fall back to zfs_sb_prune_aliases if the kernel's per-superblock
         * shrinker couldn't free anything, possibly due to the inodes being
         * allocated in a different memcg.
         */
        if (*objects == 0)
                *objects = zfs_sb_prune_aliases(zsb, nr_to_scan);
#endif

        ZFS_EXIT(zsb);

        dprintf_ds(zsb->z_os->os_dsl_dataset,
            "pruning, nr_to_scan=%lu objects=%d error=%d\n",
            nr_to_scan, *objects, error);

        return (error);
}
EXPORT_SYMBOL(zfs_sb_prune);

/*
 * Teardown the zfs_sb_t.
 *
 * Note, if 'unmounting' if FALSE, we return with the 'z_teardown_lock'
 * and 'z_teardown_inactive_lock' held.
 */
int
zfs_sb_teardown(zfs_sb_t *zsb, boolean_t unmounting)
{
        znode_t *zp;

        /*
         * If someone has not already unmounted this file system,
         * drain the iput_taskq to ensure all active references to the
         * zfs_sb_t have been handled only then can it be safely destroyed.
         */
        if (zsb->z_os) {
                /*
                 * If we're unmounting we have to wait for the list to
                 * drain completely.
                 *
                 * If we're not unmounting there's no guarantee the list
                 * will drain completely, but iputs run from the taskq
                 * may add the parents of dir-based xattrs to the taskq
                 * so we want to wait for these.
                 *
                 * We can safely read z_nr_znodes without locking because the
                 * VFS has already blocked operations which add to the
                 * z_all_znodes list and thus increment z_nr_znodes.
                 */
                int round = 0;
                while (zsb->z_nr_znodes > 0) {
                        taskq_wait_outstanding(dsl_pool_iput_taskq(
                            dmu_objset_pool(zsb->z_os)), 0);
                        if (++round > 1 && !unmounting)
                                break;
                }
        }

        rrm_enter(&zsb->z_teardown_lock, RW_WRITER, FTAG);

        if (!unmounting) {
                /*
                 * We purge the parent filesystem's super block as the
                 * parent filesystem and all of its snapshots have their
                 * inode's super block set to the parent's filesystem's
                 * super block.  Note,  'z_parent' is self referential
                 * for non-snapshots.
                 */
                shrink_dcache_sb(zsb->z_parent->z_sb);
        }

        /*
         * Close the zil. NB: Can't close the zil while zfs_inactive
         * threads are blocked as zil_close can call zfs_inactive.
         */
        if (zsb->z_log) {
                zil_close(zsb->z_log);
                zsb->z_log = NULL;
        }

        rw_enter(&zsb->z_teardown_inactive_lock, RW_WRITER);

        /*
         * If we are not unmounting (ie: online recv) and someone already
         * unmounted this file system while we were doing the switcheroo,
         * or a reopen of z_os failed then just bail out now.
         */
        if (!unmounting && (zsb->z_unmounted || zsb->z_os == NULL)) {
                rw_exit(&zsb->z_teardown_inactive_lock);
                rrm_exit(&zsb->z_teardown_lock, FTAG);
                return (SET_ERROR(EIO));
        }

        /*
         * At this point there are no VFS ops active, and any new VFS ops
         * will fail with EIO since we have z_teardown_lock for writer (only
         * relevant for forced unmount).
         *
         * Release all holds on dbufs.
         */
        if (!unmounting) {
                mutex_enter(&zsb->z_znodes_lock);
                for (zp = list_head(&zsb->z_all_znodes); zp != NULL;
                zp = list_next(&zsb->z_all_znodes, zp)) {
                        if (zp->z_sa_hdl)
                                zfs_znode_dmu_fini(zp);
                }
                mutex_exit(&zsb->z_znodes_lock);
        }

        /*
         * If we are unmounting, set the unmounted flag and let new VFS ops
         * unblock.  zfs_inactive will have the unmounted behavior, and all
         * other VFS ops will fail with EIO.
         */
        if (unmounting) {
                zsb->z_unmounted = B_TRUE;
                rrm_exit(&zsb->z_teardown_lock, FTAG);
                rw_exit(&zsb->z_teardown_inactive_lock);
        }

        /*
         * z_os will be NULL if there was an error in attempting to reopen
         * zsb, so just return as the properties had already been
         *
         * unregistered and cached data had been evicted before.
         */
        if (zsb->z_os == NULL)
                return (0);

        /*
         * Unregister properties.
         */
        zfs_unregister_callbacks(zsb);

        /*
         * Evict cached data
         */
        if (dsl_dataset_is_dirty(dmu_objset_ds(zsb->z_os)) &&
            !zfs_is_readonly(zsb))
                txg_wait_synced(dmu_objset_pool(zsb->z_os), 0);
        dmu_objset_evict_dbufs(zsb->z_os);

        return (0);
}
EXPORT_SYMBOL(zfs_sb_teardown);

#if !defined(HAVE_2ARGS_BDI_SETUP_AND_REGISTER) && \
        !defined(HAVE_3ARGS_BDI_SETUP_AND_REGISTER)
atomic_long_t zfs_bdi_seq = ATOMIC_LONG_INIT(0);
#endif

int
zfs_domount(struct super_block *sb, zfs_mntopts_t *zmo, int silent)
{
        const char *osname = zmo->z_osname;
        zfs_sb_t *zsb;
        struct inode *root_inode;
        uint64_t recordsize;
        int error;

        error = zfs_sb_create(osname, zmo, &zsb);
        if (error)
                return (error);

        if ((error = dsl_prop_get_integer(osname, "recordsize",
            &recordsize, NULL)))
                goto out;

        zsb->z_sb = sb;
        sb->s_fs_info = zsb;
        sb->s_magic = ZFS_SUPER_MAGIC;
        sb->s_maxbytes = MAX_LFS_FILESIZE;
        sb->s_time_gran = 1;
        sb->s_blocksize = recordsize;
        sb->s_blocksize_bits = ilog2(recordsize);
        zsb->z_bdi.ra_pages = 0;
        sb->s_bdi = &zsb->z_bdi;

        error = -zpl_bdi_setup_and_register(&zsb->z_bdi, "zfs");
        if (error)
                goto out;

        /* Set callback operations for the file system. */
        sb->s_op = &zpl_super_operations;
        sb->s_xattr = zpl_xattr_handlers;
        sb->s_export_op = &zpl_export_operations;
#ifdef HAVE_S_D_OP
        sb->s_d_op = &zpl_dentry_operations;
#endif /* HAVE_S_D_OP */

        /* Set features for file system. */
        zfs_set_fuid_feature(zsb);

        if (dmu_objset_is_snapshot(zsb->z_os)) {
                uint64_t pval;

                atime_changed_cb(zsb, B_FALSE);
                readonly_changed_cb(zsb, B_TRUE);
                if ((error = dsl_prop_get_integer(osname,
                    "xattr", &pval, NULL)))
                        goto out;
                xattr_changed_cb(zsb, pval);
                if ((error = dsl_prop_get_integer(osname,
                    "acltype", &pval, NULL)))
                        goto out;
                acltype_changed_cb(zsb, pval);
                zsb->z_issnap = B_TRUE;
                zsb->z_os->os_sync = ZFS_SYNC_DISABLED;
                zsb->z_snap_defer_time = jiffies;

                mutex_enter(&zsb->z_os->os_user_ptr_lock);
                dmu_objset_set_user(zsb->z_os, zsb);
                mutex_exit(&zsb->z_os->os_user_ptr_lock);
        } else {
                if ((error = zfs_sb_setup(zsb, B_TRUE)))
                        goto out;
        }

        /* Allocate a root inode for the filesystem. */
        error = zfs_root(zsb, &root_inode);
        if (error) {
                (void) zfs_umount(sb);
                goto out;
        }

        /* Allocate a root dentry for the filesystem */
        sb->s_root = d_make_root(root_inode);
        if (sb->s_root == NULL) {
                (void) zfs_umount(sb);
                error = SET_ERROR(ENOMEM);
                goto out;
        }

        if (!zsb->z_issnap)
                zfsctl_create(zsb);

        zsb->z_arc_prune = arc_add_prune_callback(zpl_prune_sb, sb);
out:
        if (error) {
                dmu_objset_disown(zsb->z_os, zsb);
                zfs_sb_free(zsb);
                /*
                 * make sure we don't have dangling sb->s_fs_info which
                 * zfs_preumount will use.
                 */
                sb->s_fs_info = NULL;
        }

        return (error);
}
EXPORT_SYMBOL(zfs_domount);

/*
 * Called when an unmount is requested and certain sanity checks have
 * already passed.  At this point no dentries or inodes have been reclaimed
 * from their respective caches.  We drop the extra reference on the .zfs
 * control directory to allow everything to be reclaimed.  All snapshots
 * must already have been unmounted to reach this point.
 */
void
zfs_preumount(struct super_block *sb)
{
        zfs_sb_t *zsb = sb->s_fs_info;

        /* zsb is NULL when zfs_domount fails during mount */
        if (zsb) {
                zfsctl_destroy(sb->s_fs_info);
                /*
                 * Wait for iput_async before entering evict_inodes in
                 * generic_shutdown_super. The reason we must finish before
                 * evict_inodes is when lazytime is on, or when zfs_purgedir
                 * calls zfs_zget, iput would bump i_count from 0 to 1. This
                 * would race with the i_count check in evict_inodes. This means
                 * it could destroy the inode while we are still using it.
                 *
                 * We wait for two passes. xattr directories in the first pass
                 * may add xattr entries in zfs_purgedir, so in the second pass
                 * we wait for them. We don't use taskq_wait here because it is
                 * a pool wide taskq. Other mounted filesystems can constantly
                 * do iput_async and there's no guarantee when taskq will be
                 * empty.
                 */
                taskq_wait_outstanding(dsl_pool_iput_taskq(
                    dmu_objset_pool(zsb->z_os)), 0);
                taskq_wait_outstanding(dsl_pool_iput_taskq(
                    dmu_objset_pool(zsb->z_os)), 0);
        }
}
EXPORT_SYMBOL(zfs_preumount);

/*
 * Called once all other unmount released tear down has occurred.
 * It is our responsibility to release any remaining infrastructure.
 */
/*ARGSUSED*/
int
zfs_umount(struct super_block *sb)
{
        zfs_sb_t *zsb = sb->s_fs_info;
        objset_t *os;

        arc_remove_prune_callback(zsb->z_arc_prune);
        VERIFY(zfs_sb_teardown(zsb, B_TRUE) == 0);
        os = zsb->z_os;
        bdi_destroy(sb->s_bdi);

        /*
         * z_os will be NULL if there was an error in
         * attempting to reopen zsb.
         */
        if (os != NULL) {
                /*
                 * Unset the objset user_ptr.
                 */
                mutex_enter(&os->os_user_ptr_lock);
                dmu_objset_set_user(os, NULL);
                mutex_exit(&os->os_user_ptr_lock);

                /*
                 * Finally release the objset
                 */
                dmu_objset_disown(os, zsb);
        }

        zfs_sb_free(zsb);
        return (0);
}
EXPORT_SYMBOL(zfs_umount);

int
zfs_remount(struct super_block *sb, int *flags, zfs_mntopts_t *zmo)
{
        zfs_sb_t *zsb = sb->s_fs_info;
        int error;

        zfs_unregister_callbacks(zsb);
        error = zfs_register_callbacks(zsb);

        return (error);
}
EXPORT_SYMBOL(zfs_remount);

int
zfs_vget(struct super_block *sb, struct inode **ipp, fid_t *fidp)
{
        zfs_sb_t        *zsb = sb->s_fs_info;
        znode_t         *zp;
        uint64_t        object = 0;
        uint64_t        fid_gen = 0;
        uint64_t        gen_mask;
        uint64_t        zp_gen;
        int             i, err;

        *ipp = NULL;

        ZFS_ENTER(zsb);

        if (fidp->fid_len == LONG_FID_LEN) {
                zfid_long_t     *zlfid = (zfid_long_t *)fidp;
                uint64_t        objsetid = 0;
                uint64_t        setgen = 0;

                for (i = 0; i < sizeof (zlfid->zf_setid); i++)
                        objsetid |= ((uint64_t)zlfid->zf_setid[i]) << (8 * i);

                for (i = 0; i < sizeof (zlfid->zf_setgen); i++)
                        setgen |= ((uint64_t)zlfid->zf_setgen[i]) << (8 * i);

                ZFS_EXIT(zsb);

                err = zfsctl_lookup_objset(sb, objsetid, &zsb);
                if (err)
                        return (SET_ERROR(EINVAL));

                ZFS_ENTER(zsb);
        }

        if (fidp->fid_len == SHORT_FID_LEN || fidp->fid_len == LONG_FID_LEN) {
                zfid_short_t    *zfid = (zfid_short_t *)fidp;

                for (i = 0; i < sizeof (zfid->zf_object); i++)
                        object |= ((uint64_t)zfid->zf_object[i]) << (8 * i);

                for (i = 0; i < sizeof (zfid->zf_gen); i++)
                        fid_gen |= ((uint64_t)zfid->zf_gen[i]) << (8 * i);
        } else {
                ZFS_EXIT(zsb);
                return (SET_ERROR(EINVAL));
        }

        /* A zero fid_gen means we are in the .zfs control directories */
        if (fid_gen == 0 &&
            (object == ZFSCTL_INO_ROOT || object == ZFSCTL_INO_SNAPDIR)) {
                *ipp = zsb->z_ctldir;
                ASSERT(*ipp != NULL);
                if (object == ZFSCTL_INO_SNAPDIR) {
                        VERIFY(zfsctl_root_lookup(*ipp, "snapshot", ipp,
                            0, kcred, NULL, NULL) == 0);
                } else {
                        igrab(*ipp);
                }
                ZFS_EXIT(zsb);
                return (0);
        }

        gen_mask = -1ULL >> (64 - 8 * i);

        dprintf("getting %llu [%llu mask %llx]\n", object, fid_gen, gen_mask);
        if ((err = zfs_zget(zsb, object, &zp))) {
                ZFS_EXIT(zsb);
                return (err);
        }

        /* Don't export xattr stuff */
        if (zp->z_pflags & ZFS_XATTR) {
                iput(ZTOI(zp));
                ZFS_EXIT(zsb);
                return (SET_ERROR(ENOENT));
        }

        (void) sa_lookup(zp->z_sa_hdl, SA_ZPL_GEN(zsb), &zp_gen,
            sizeof (uint64_t));
        zp_gen = zp_gen & gen_mask;
        if (zp_gen == 0)
                zp_gen = 1;
        if ((fid_gen == 0) && (zsb->z_root == object))
                fid_gen = zp_gen;
        if (zp->z_unlinked || zp_gen != fid_gen) {
                dprintf("znode gen (%llu) != fid gen (%llu)\n", zp_gen,
                    fid_gen);
                iput(ZTOI(zp));
                ZFS_EXIT(zsb);
                return (SET_ERROR(ENOENT));
        }

        *ipp = ZTOI(zp);
        if (*ipp)
                zfs_inode_update(ITOZ(*ipp));

        ZFS_EXIT(zsb);
        return (0);
}
EXPORT_SYMBOL(zfs_vget);

/*
 * Block out VFS ops and close zfs_sb_t
 *
 * Note, if successful, then we return with the 'z_teardown_lock' and
 * 'z_teardown_inactive_lock' write held.  We leave ownership of the underlying
 * dataset and objset intact so that they can be atomically handed off during
 * a subsequent rollback or recv operation and the resume thereafter.
 */
int
zfs_suspend_fs(zfs_sb_t *zsb)
{
        int error;

        if ((error = zfs_sb_teardown(zsb, B_FALSE)) != 0)
                return (error);

        return (0);
}
EXPORT_SYMBOL(zfs_suspend_fs);

/*
 * Reopen zfs_sb_t and release VFS ops.
 */
int
zfs_resume_fs(zfs_sb_t *zsb, const char *osname)
{
        int err, err2;
        znode_t *zp;
        uint64_t sa_obj = 0;

        ASSERT(RRM_WRITE_HELD(&zsb->z_teardown_lock));
        ASSERT(RW_WRITE_HELD(&zsb->z_teardown_inactive_lock));

        /*
         * We already own this, so just hold and rele it to update the
         * objset_t, as the one we had before may have been evicted.
         */
        VERIFY0(dmu_objset_hold(osname, zsb, &zsb->z_os));
        VERIFY3P(zsb->z_os->os_dsl_dataset->ds_owner, ==, zsb);
        VERIFY(dsl_dataset_long_held(zsb->z_os->os_dsl_dataset));
        dmu_objset_rele(zsb->z_os, zsb);

        /*
         * Make sure version hasn't changed
         */

        err = zfs_get_zplprop(zsb->z_os, ZFS_PROP_VERSION,
            &zsb->z_version);

        if (err)
                goto bail;

        err = zap_lookup(zsb->z_os, MASTER_NODE_OBJ,
            ZFS_SA_ATTRS, 8, 1, &sa_obj);

        if (err && zsb->z_version >= ZPL_VERSION_SA)
                goto bail;

        if ((err = sa_setup(zsb->z_os, sa_obj,
            zfs_attr_table,  ZPL_END, &zsb->z_attr_table)) != 0)
                goto bail;

        if (zsb->z_version >= ZPL_VERSION_SA)
                sa_register_update_callback(zsb->z_os,
                    zfs_sa_upgrade);

        VERIFY(zfs_sb_setup(zsb, B_FALSE) == 0);

        zfs_set_fuid_feature(zsb);
        zsb->z_rollback_time = jiffies;

        /*
         * Attempt to re-establish all the active inodes with their
         * dbufs.  If a zfs_rezget() fails, then we unhash the inode
         * and mark it stale.  This prevents a collision if a new
         * inode/object is created which must use the same inode
         * number.  The stale inode will be be released when the
         * VFS prunes the dentry holding the remaining references
         * on the stale inode.
         */
        mutex_enter(&zsb->z_znodes_lock);
        for (zp = list_head(&zsb->z_all_znodes); zp;
            zp = list_next(&zsb->z_all_znodes, zp)) {
                err2 = zfs_rezget(zp);
                if (err2) {
                        remove_inode_hash(ZTOI(zp));
                        zp->z_is_stale = B_TRUE;
                }
        }
        mutex_exit(&zsb->z_znodes_lock);

bail:
        /* release the VFS ops */
        rw_exit(&zsb->z_teardown_inactive_lock);
        rrm_exit(&zsb->z_teardown_lock, FTAG);

        if (err) {
                /*
                 * Since we couldn't setup the sa framework, try to force
                 * unmount this file system.
                 */
                if (zsb->z_os)
                        (void) zfs_umount(zsb->z_sb);
        }
        return (err);
}
EXPORT_SYMBOL(zfs_resume_fs);

int
zfs_set_version(zfs_sb_t *zsb, uint64_t newvers)
{
        int error;
        objset_t *os = zsb->z_os;
        dmu_tx_t *tx;

        if (newvers < ZPL_VERSION_INITIAL || newvers > ZPL_VERSION)
                return (SET_ERROR(EINVAL));

        if (newvers < zsb->z_version)
                return (SET_ERROR(EINVAL));

        if (zfs_spa_version_map(newvers) >
            spa_version(dmu_objset_spa(zsb->z_os)))
                return (SET_ERROR(ENOTSUP));

        tx = dmu_tx_create(os);
        dmu_tx_hold_zap(tx, MASTER_NODE_OBJ, B_FALSE, ZPL_VERSION_STR);
        if (newvers >= ZPL_VERSION_SA && !zsb->z_use_sa) {
                dmu_tx_hold_zap(tx, MASTER_NODE_OBJ, B_TRUE,
                    ZFS_SA_ATTRS);
                dmu_tx_hold_zap(tx, DMU_NEW_OBJECT, FALSE, NULL);
        }
        error = dmu_tx_assign(tx, TXG_WAIT);
        if (error) {
                dmu_tx_abort(tx);
                return (error);
        }

        error = zap_update(os, MASTER_NODE_OBJ, ZPL_VERSION_STR,
            8, 1, &newvers, tx);

        if (error) {
                dmu_tx_commit(tx);
                return (error);
        }

        if (newvers >= ZPL_VERSION_SA && !zsb->z_use_sa) {
                uint64_t sa_obj;

                ASSERT3U(spa_version(dmu_objset_spa(zsb->z_os)), >=,
                    SPA_VERSION_SA);
                sa_obj = zap_create(os, DMU_OT_SA_MASTER_NODE,
                    DMU_OT_NONE, 0, tx);

                error = zap_add(os, MASTER_NODE_OBJ,
                    ZFS_SA_ATTRS, 8, 1, &sa_obj, tx);
                ASSERT0(error);

                VERIFY(0 == sa_set_sa_object(os, sa_obj));
                sa_register_update_callback(os, zfs_sa_upgrade);
        }

        spa_history_log_internal_ds(dmu_objset_ds(os), "upgrade", tx,
            "from %llu to %llu", zsb->z_version, newvers);

        dmu_tx_commit(tx);

        zsb->z_version = newvers;

        zfs_set_fuid_feature(zsb);

        return (0);
}
EXPORT_SYMBOL(zfs_set_version);

/*
 * Read a property stored within the master node.
 */
int
zfs_get_zplprop(objset_t *os, zfs_prop_t prop, uint64_t *value)
{
        const char *pname;
        int error = SET_ERROR(ENOENT);

        /*
         * Look up the file system's value for the property.  For the
         * version property, we look up a slightly different string.
         */
        if (prop == ZFS_PROP_VERSION)
                pname = ZPL_VERSION_STR;
        else
                pname = zfs_prop_to_name(prop);

        if (os != NULL)
                error = zap_lookup(os, MASTER_NODE_OBJ, pname, 8, 1, value);

        if (error == ENOENT) {
                /* No value set, use the default value */
                switch (prop) {
                case ZFS_PROP_VERSION:
                        *value = ZPL_VERSION;
                        break;
                case ZFS_PROP_NORMALIZE:
                case ZFS_PROP_UTF8ONLY:
                        *value = 0;
                        break;
                case ZFS_PROP_CASE:
                        *value = ZFS_CASE_SENSITIVE;
                        break;
                case ZFS_PROP_ACLTYPE:
                        *value = ZFS_ACLTYPE_OFF;
                        break;
                default:
                        return (error);
                }
                error = 0;
        }
        return (error);
}
EXPORT_SYMBOL(zfs_get_zplprop);

void
zfs_init(void)
{
        zfsctl_init();
        zfs_znode_init();
        dmu_objset_register_type(DMU_OST_ZFS, zfs_space_delta_cb);
        register_filesystem(&zpl_fs_type);
}

void
zfs_fini(void)
{
        taskq_wait_outstanding(system_taskq, 0);
        unregister_filesystem(&zpl_fs_type);
        zfs_znode_fini();
        zfsctl_fini();
}