Rebase master to b121

[mirror_zfs-debian.git] / module / zfs / zfs_znode.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 2009 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

/* Portions Copyright 2007 Jeremy Teo */

#ifdef _KERNEL
#include <sys/types.h>
#include <sys/param.h>
#include <sys/time.h>
#include <sys/systm.h>
#include <sys/sysmacros.h>
#include <sys/resource.h>
#include <sys/mntent.h>
#include <sys/mkdev.h>
#include <sys/u8_textprep.h>
#include <sys/dsl_dataset.h>
#include <sys/vfs.h>
#include <sys/vfs_opreg.h>
#include <sys/vnode.h>
#include <sys/file.h>
#include <sys/kmem.h>
#include <sys/errno.h>
#include <sys/unistd.h>
#include <sys/mode.h>
#include <sys/atomic.h>
#include <vm/pvn.h>
#include "fs/fs_subr.h"
#include <sys/zfs_dir.h>
#include <sys/zfs_acl.h>
#include <sys/zfs_ioctl.h>
#include <sys/zfs_rlock.h>
#include <sys/zfs_fuid.h>
#include <sys/fs/zfs.h>
#include <sys/kidmap.h>
#endif /* _KERNEL */

#include <sys/dmu.h>
#include <sys/refcount.h>
#include <sys/stat.h>
#include <sys/zap.h>
#include <sys/zfs_znode.h>

#include "zfs_prop.h"

/*
 * Define ZNODE_STATS to turn on statistic gathering. By default, it is only
 * turned on when DEBUG is also defined.
 */
#ifdef  DEBUG
#define ZNODE_STATS
#endif  /* DEBUG */

#ifdef  ZNODE_STATS
#define ZNODE_STAT_ADD(stat)                    ((stat)++)
#else
#define ZNODE_STAT_ADD(stat)                    /* nothing */
#endif  /* ZNODE_STATS */

#define POINTER_IS_VALID(p)     (!((uintptr_t)(p) & 0x3))
#define POINTER_INVALIDATE(pp)  (*(pp) = (void *)((uintptr_t)(*(pp)) | 0x1))

/*
 * Functions needed for userland (ie: libzpool) are not put under
 * #ifdef_KERNEL; the rest of the functions have dependencies
 * (such as VFS logic) that will not compile easily in userland.
 */
#ifdef _KERNEL
/*
 * Needed to close a small window in zfs_znode_move() that allows the zfsvfs to
 * be freed before it can be safely accessed.
 */
krwlock_t zfsvfs_lock;

static kmem_cache_t *znode_cache = NULL;

/*ARGSUSED*/
static void
znode_evict_error(dmu_buf_t *dbuf, void *user_ptr)
{
        /*
         * We should never drop all dbuf refs without first clearing
         * the eviction callback.
         */
        panic("evicting znode %p\n", user_ptr);
}

/*ARGSUSED*/
static int
zfs_znode_cache_constructor(void *buf, void *arg, int kmflags)
{
        znode_t *zp = buf;

        ASSERT(!POINTER_IS_VALID(zp->z_zfsvfs));

        zp->z_vnode = vn_alloc(kmflags);
        if (zp->z_vnode == NULL) {
                return (-1);
        }
        ZTOV(zp)->v_data = zp;

        list_link_init(&zp->z_link_node);

        mutex_init(&zp->z_lock, NULL, MUTEX_DEFAULT, NULL);
        rw_init(&zp->z_parent_lock, NULL, RW_DEFAULT, NULL);
        rw_init(&zp->z_name_lock, NULL, RW_DEFAULT, NULL);
        mutex_init(&zp->z_acl_lock, NULL, MUTEX_DEFAULT, NULL);

        mutex_init(&zp->z_range_lock, NULL, MUTEX_DEFAULT, NULL);
        avl_create(&zp->z_range_avl, zfs_range_compare,
            sizeof (rl_t), offsetof(rl_t, r_node));

        zp->z_dbuf = NULL;
        zp->z_dirlocks = NULL;
        zp->z_acl_cached = NULL;
        return (0);
}

/*ARGSUSED*/
static void
zfs_znode_cache_destructor(void *buf, void *arg)
{
        znode_t *zp = buf;

        ASSERT(!POINTER_IS_VALID(zp->z_zfsvfs));
        ASSERT(ZTOV(zp)->v_data == zp);
        vn_free(ZTOV(zp));
        ASSERT(!list_link_active(&zp->z_link_node));
        mutex_destroy(&zp->z_lock);
        rw_destroy(&zp->z_parent_lock);
        rw_destroy(&zp->z_name_lock);
        mutex_destroy(&zp->z_acl_lock);
        avl_destroy(&zp->z_range_avl);
        mutex_destroy(&zp->z_range_lock);

        ASSERT(zp->z_dbuf == NULL);
        ASSERT(zp->z_dirlocks == NULL);
        ASSERT(zp->z_acl_cached == NULL);
}

#ifdef  ZNODE_STATS
static struct {
        uint64_t zms_zfsvfs_invalid;
        uint64_t zms_zfsvfs_recheck1;
        uint64_t zms_zfsvfs_unmounted;
        uint64_t zms_zfsvfs_recheck2;
        uint64_t zms_obj_held;
        uint64_t zms_vnode_locked;
        uint64_t zms_not_only_dnlc;
} znode_move_stats;
#endif  /* ZNODE_STATS */

static void
zfs_znode_move_impl(znode_t *ozp, znode_t *nzp)
{
        vnode_t *vp;

        /* Copy fields. */
        nzp->z_zfsvfs = ozp->z_zfsvfs;

        /* Swap vnodes. */
        vp = nzp->z_vnode;
        nzp->z_vnode = ozp->z_vnode;
        ozp->z_vnode = vp; /* let destructor free the overwritten vnode */
        ZTOV(ozp)->v_data = ozp;
        ZTOV(nzp)->v_data = nzp;

        nzp->z_id = ozp->z_id;
        ASSERT(ozp->z_dirlocks == NULL); /* znode not in use */
        ASSERT(avl_numnodes(&ozp->z_range_avl) == 0);
        nzp->z_unlinked = ozp->z_unlinked;
        nzp->z_atime_dirty = ozp->z_atime_dirty;
        nzp->z_zn_prefetch = ozp->z_zn_prefetch;
        nzp->z_blksz = ozp->z_blksz;
        nzp->z_seq = ozp->z_seq;
        nzp->z_mapcnt = ozp->z_mapcnt;
        nzp->z_last_itx = ozp->z_last_itx;
        nzp->z_gen = ozp->z_gen;
        nzp->z_sync_cnt = ozp->z_sync_cnt;
        nzp->z_phys = ozp->z_phys;
        nzp->z_dbuf = ozp->z_dbuf;

        /*
         * Release any cached ACL, since it *may* have
         * zfs_acl_node_t's that directly references an
         * embedded ACL in the zp_acl of the old znode_phys_t
         *
         * It will be recached the next time the ACL is needed.
         */
        if (ozp->z_acl_cached) {
                zfs_acl_free(ozp->z_acl_cached);
                ozp->z_acl_cached = NULL;
        }

        /* Update back pointers. */
        (void) dmu_buf_update_user(nzp->z_dbuf, ozp, nzp, &nzp->z_phys,
            znode_evict_error);

        /*
         * Invalidate the original znode by clearing fields that provide a
         * pointer back to the znode. Set the low bit of the vfs pointer to
         * ensure that zfs_znode_move() recognizes the znode as invalid in any
         * subsequent callback.
         */
        ozp->z_dbuf = NULL;
        POINTER_INVALIDATE(&ozp->z_zfsvfs);
}

/*ARGSUSED*/
static kmem_cbrc_t
zfs_znode_move(void *buf, void *newbuf, size_t size, void *arg)
{
        znode_t *ozp = buf, *nzp = newbuf;
        zfsvfs_t *zfsvfs;
        vnode_t *vp;

        /*
         * The znode is on the file system's list of known znodes if the vfs
         * pointer is valid. We set the low bit of the vfs pointer when freeing
         * the znode to invalidate it, and the memory patterns written by kmem
         * (baddcafe and deadbeef) set at least one of the two low bits. A newly
         * created znode sets the vfs pointer last of all to indicate that the
         * znode is known and in a valid state to be moved by this function.
         */
        zfsvfs = ozp->z_zfsvfs;
        if (!POINTER_IS_VALID(zfsvfs)) {
                ZNODE_STAT_ADD(znode_move_stats.zms_zfsvfs_invalid);
                return (KMEM_CBRC_DONT_KNOW);
        }

        /*
         * Close a small window in which it's possible that the filesystem could
         * be unmounted and freed, and zfsvfs, though valid in the previous
         * statement, could point to unrelated memory by the time we try to
         * prevent the filesystem from being unmounted.
         */
        rw_enter(&zfsvfs_lock, RW_WRITER);
        if (zfsvfs != ozp->z_zfsvfs) {
                rw_exit(&zfsvfs_lock);
                ZNODE_STAT_ADD(znode_move_stats.zms_zfsvfs_recheck1);
                return (KMEM_CBRC_DONT_KNOW);
        }

        /*
         * If the znode is still valid, then so is the file system. We know that
         * no valid file system can be freed while we hold zfsvfs_lock, so we
         * can safely ensure that the filesystem is not and will not be
         * unmounted. The next statement is equivalent to ZFS_ENTER().
         */
        rrw_enter(&zfsvfs->z_teardown_lock, RW_READER, FTAG);
        if (zfsvfs->z_unmounted) {
                ZFS_EXIT(zfsvfs);
                rw_exit(&zfsvfs_lock);
                ZNODE_STAT_ADD(znode_move_stats.zms_zfsvfs_unmounted);
                return (KMEM_CBRC_DONT_KNOW);
        }
        rw_exit(&zfsvfs_lock);

        mutex_enter(&zfsvfs->z_znodes_lock);
        /*
         * Recheck the vfs pointer in case the znode was removed just before
         * acquiring the lock.
         */
        if (zfsvfs != ozp->z_zfsvfs) {
                mutex_exit(&zfsvfs->z_znodes_lock);
                ZFS_EXIT(zfsvfs);
                ZNODE_STAT_ADD(znode_move_stats.zms_zfsvfs_recheck2);
                return (KMEM_CBRC_DONT_KNOW);
        }

        /*
         * At this point we know that as long as we hold z_znodes_lock, the
         * znode cannot be freed and fields within the znode can be safely
         * accessed. Now, prevent a race with zfs_zget().
         */
        if (ZFS_OBJ_HOLD_TRYENTER(zfsvfs, ozp->z_id) == 0) {
                mutex_exit(&zfsvfs->z_znodes_lock);
                ZFS_EXIT(zfsvfs);
                ZNODE_STAT_ADD(znode_move_stats.zms_obj_held);
                return (KMEM_CBRC_LATER);
        }

        vp = ZTOV(ozp);
        if (mutex_tryenter(&vp->v_lock) == 0) {
                ZFS_OBJ_HOLD_EXIT(zfsvfs, ozp->z_id);
                mutex_exit(&zfsvfs->z_znodes_lock);
                ZFS_EXIT(zfsvfs);
                ZNODE_STAT_ADD(znode_move_stats.zms_vnode_locked);
                return (KMEM_CBRC_LATER);
        }

        /* Only move znodes that are referenced _only_ by the DNLC. */
        if (vp->v_count != 1 || !vn_in_dnlc(vp)) {
                mutex_exit(&vp->v_lock);
                ZFS_OBJ_HOLD_EXIT(zfsvfs, ozp->z_id);
                mutex_exit(&zfsvfs->z_znodes_lock);
                ZFS_EXIT(zfsvfs);
                ZNODE_STAT_ADD(znode_move_stats.zms_not_only_dnlc);
                return (KMEM_CBRC_LATER);
        }

        /*
         * The znode is known and in a valid state to move. We're holding the
         * locks needed to execute the critical section.
         */
        zfs_znode_move_impl(ozp, nzp);
        mutex_exit(&vp->v_lock);
        ZFS_OBJ_HOLD_EXIT(zfsvfs, ozp->z_id);

        list_link_replace(&ozp->z_link_node, &nzp->z_link_node);
        mutex_exit(&zfsvfs->z_znodes_lock);
        ZFS_EXIT(zfsvfs);

        return (KMEM_CBRC_YES);
}

void
zfs_znode_init(void)
{
        /*
         * Initialize zcache
         */
        rw_init(&zfsvfs_lock, NULL, RW_DEFAULT, NULL);
        ASSERT(znode_cache == NULL);
        znode_cache = kmem_cache_create("zfs_znode_cache",
            sizeof (znode_t), 0, zfs_znode_cache_constructor,
            zfs_znode_cache_destructor, NULL, NULL, NULL, 0);
        kmem_cache_set_move(znode_cache, zfs_znode_move);
}

void
zfs_znode_fini(void)
{
        /*
         * Cleanup vfs & vnode ops
         */
        zfs_remove_op_tables();

        /*
         * Cleanup zcache
         */
        if (znode_cache)
                kmem_cache_destroy(znode_cache);
        znode_cache = NULL;
        rw_destroy(&zfsvfs_lock);
}

struct vnodeops *zfs_dvnodeops;
struct vnodeops *zfs_fvnodeops;
struct vnodeops *zfs_symvnodeops;
struct vnodeops *zfs_xdvnodeops;
struct vnodeops *zfs_evnodeops;
struct vnodeops *zfs_sharevnodeops;

void
zfs_remove_op_tables()
{
        /*
         * Remove vfs ops
         */
        ASSERT(zfsfstype);
        (void) vfs_freevfsops_by_type(zfsfstype);
        zfsfstype = 0;

        /*
         * Remove vnode ops
         */
        if (zfs_dvnodeops)
                vn_freevnodeops(zfs_dvnodeops);
        if (zfs_fvnodeops)
                vn_freevnodeops(zfs_fvnodeops);
        if (zfs_symvnodeops)
                vn_freevnodeops(zfs_symvnodeops);
        if (zfs_xdvnodeops)
                vn_freevnodeops(zfs_xdvnodeops);
        if (zfs_evnodeops)
                vn_freevnodeops(zfs_evnodeops);
        if (zfs_sharevnodeops)
                vn_freevnodeops(zfs_sharevnodeops);

        zfs_dvnodeops = NULL;
        zfs_fvnodeops = NULL;
        zfs_symvnodeops = NULL;
        zfs_xdvnodeops = NULL;
        zfs_evnodeops = NULL;
        zfs_sharevnodeops = NULL;
}

extern const fs_operation_def_t zfs_dvnodeops_template[];
extern const fs_operation_def_t zfs_fvnodeops_template[];
extern const fs_operation_def_t zfs_xdvnodeops_template[];
extern const fs_operation_def_t zfs_symvnodeops_template[];
extern const fs_operation_def_t zfs_evnodeops_template[];
extern const fs_operation_def_t zfs_sharevnodeops_template[];

int
zfs_create_op_tables()
{
        int error;

        /*
         * zfs_dvnodeops can be set if mod_remove() calls mod_installfs()
         * due to a failure to remove the the 2nd modlinkage (zfs_modldrv).
         * In this case we just return as the ops vectors are already set up.
         */
        if (zfs_dvnodeops)
                return (0);

        error = vn_make_ops(MNTTYPE_ZFS, zfs_dvnodeops_template,
            &zfs_dvnodeops);
        if (error)
                return (error);

        error = vn_make_ops(MNTTYPE_ZFS, zfs_fvnodeops_template,
            &zfs_fvnodeops);
        if (error)
                return (error);

        error = vn_make_ops(MNTTYPE_ZFS, zfs_symvnodeops_template,
            &zfs_symvnodeops);
        if (error)
                return (error);

        error = vn_make_ops(MNTTYPE_ZFS, zfs_xdvnodeops_template,
            &zfs_xdvnodeops);
        if (error)
                return (error);

        error = vn_make_ops(MNTTYPE_ZFS, zfs_evnodeops_template,
            &zfs_evnodeops);
        if (error)
                return (error);

        error = vn_make_ops(MNTTYPE_ZFS, zfs_sharevnodeops_template,
            &zfs_sharevnodeops);

        return (error);
}

int
zfs_create_share_dir(zfsvfs_t *zfsvfs, dmu_tx_t *tx)
{
        zfs_acl_ids_t acl_ids;
        vattr_t vattr;
        znode_t *sharezp;
        vnode_t *vp;
        znode_t *zp;
        int error;

        vattr.va_mask = AT_MODE|AT_UID|AT_GID|AT_TYPE;
        vattr.va_type = VDIR;
        vattr.va_mode = S_IFDIR|0555;
        vattr.va_uid = crgetuid(kcred);
        vattr.va_gid = crgetgid(kcred);

        sharezp = kmem_cache_alloc(znode_cache, KM_SLEEP);
        sharezp->z_unlinked = 0;
        sharezp->z_atime_dirty = 0;
        sharezp->z_zfsvfs = zfsvfs;

        vp = ZTOV(sharezp);
        vn_reinit(vp);
        vp->v_type = VDIR;

        VERIFY(0 == zfs_acl_ids_create(sharezp, IS_ROOT_NODE, &vattr,
            kcred, NULL, &acl_ids));
        zfs_mknode(sharezp, &vattr, tx, kcred, IS_ROOT_NODE,
            &zp, 0, &acl_ids);
        ASSERT3P(zp, ==, sharezp);
        ASSERT(!vn_in_dnlc(ZTOV(sharezp))); /* not valid to move */
        POINTER_INVALIDATE(&sharezp->z_zfsvfs);
        error = zap_add(zfsvfs->z_os, MASTER_NODE_OBJ,
            ZFS_SHARES_DIR, 8, 1, &sharezp->z_id, tx);
        zfsvfs->z_shares_dir = sharezp->z_id;

        zfs_acl_ids_free(&acl_ids);
        ZTOV(sharezp)->v_count = 0;
        dmu_buf_rele(sharezp->z_dbuf, NULL);
        sharezp->z_dbuf = NULL;
        kmem_cache_free(znode_cache, sharezp);

        return (error);
}

/*
 * define a couple of values we need available
 * for both 64 and 32 bit environments.
 */
#ifndef NBITSMINOR64
#define NBITSMINOR64    32
#endif
#ifndef MAXMAJ64
#define MAXMAJ64        0xffffffffUL
#endif
#ifndef MAXMIN64
#define MAXMIN64        0xffffffffUL
#endif

/*
 * Create special expldev for ZFS private use.
 * Can't use standard expldev since it doesn't do
 * what we want.  The standard expldev() takes a
 * dev32_t in LP64 and expands it to a long dev_t.
 * We need an interface that takes a dev32_t in ILP32
 * and expands it to a long dev_t.
 */
static uint64_t
zfs_expldev(dev_t dev)
{
#ifndef _LP64
        major_t major = (major_t)dev >> NBITSMINOR32 & MAXMAJ32;
        return (((uint64_t)major << NBITSMINOR64) |
            ((minor_t)dev & MAXMIN32));
#else
        return (dev);
#endif
}

/*
 * Special cmpldev for ZFS private use.
 * Can't use standard cmpldev since it takes
 * a long dev_t and compresses it to dev32_t in
 * LP64.  We need to do a compaction of a long dev_t
 * to a dev32_t in ILP32.
 */
dev_t
zfs_cmpldev(uint64_t dev)
{
#ifndef _LP64
        minor_t minor = (minor_t)dev & MAXMIN64;
        major_t major = (major_t)(dev >> NBITSMINOR64) & MAXMAJ64;

        if (major > MAXMAJ32 || minor > MAXMIN32)
                return (NODEV32);

        return (((dev32_t)major << NBITSMINOR32) | minor);
#else
        return (dev);
#endif
}

static void
zfs_znode_dmu_init(zfsvfs_t *zfsvfs, znode_t *zp, dmu_buf_t *db)
{
        znode_t         *nzp;

        ASSERT(!POINTER_IS_VALID(zp->z_zfsvfs) || (zfsvfs == zp->z_zfsvfs));
        ASSERT(MUTEX_HELD(ZFS_OBJ_MUTEX(zfsvfs, zp->z_id)));

        mutex_enter(&zp->z_lock);

        ASSERT(zp->z_dbuf == NULL);
        zp->z_dbuf = db;
        nzp = dmu_buf_set_user_ie(db, zp, &zp->z_phys, znode_evict_error);

        /*
         * there should be no
         * concurrent zgets on this object.
         */
        if (nzp != NULL)
                panic("existing znode %p for dbuf %p", (void *)nzp, (void *)db);

        /*
         * Slap on VROOT if we are the root znode
         */
        if (zp->z_id == zfsvfs->z_root)
                ZTOV(zp)->v_flag |= VROOT;

        mutex_exit(&zp->z_lock);
        vn_exists(ZTOV(zp));
}

void
zfs_znode_dmu_fini(znode_t *zp)
{
        dmu_buf_t *db = zp->z_dbuf;
        ASSERT(MUTEX_HELD(ZFS_OBJ_MUTEX(zp->z_zfsvfs, zp->z_id)) ||
            zp->z_unlinked ||
            RW_WRITE_HELD(&zp->z_zfsvfs->z_teardown_inactive_lock));
        ASSERT(zp->z_dbuf != NULL);
        zp->z_dbuf = NULL;
        VERIFY(zp == dmu_buf_update_user(db, zp, NULL, NULL, NULL));
        dmu_buf_rele(db, NULL);
}

/*
 * Construct a new znode/vnode and intialize.
 *
 * This does not do a call to dmu_set_user() that is
 * up to the caller to do, in case you don't want to
 * return the znode
 */
static znode_t *
zfs_znode_alloc(zfsvfs_t *zfsvfs, dmu_buf_t *db, int blksz)
{
        znode_t *zp;
        vnode_t *vp;

        zp = kmem_cache_alloc(znode_cache, KM_SLEEP);

        ASSERT(zp->z_dirlocks == NULL);
        ASSERT(zp->z_dbuf == NULL);
        ASSERT(!POINTER_IS_VALID(zp->z_zfsvfs));

        /*
         * Defer setting z_zfsvfs until the znode is ready to be a candidate for
         * the zfs_znode_move() callback.
         */
        zp->z_phys = NULL;
        zp->z_unlinked = 0;
        zp->z_atime_dirty = 0;
        zp->z_mapcnt = 0;
        zp->z_last_itx = 0;
        zp->z_id = db->db_object;
        zp->z_blksz = blksz;
        zp->z_seq = 0x7A4653;
        zp->z_sync_cnt = 0;

        vp = ZTOV(zp);
        vn_reinit(vp);

        zfs_znode_dmu_init(zfsvfs, zp, db);

        zp->z_gen = zp->z_phys->zp_gen;

        vp->v_vfsp = zfsvfs->z_parent->z_vfs;
        vp->v_type = IFTOVT((mode_t)zp->z_phys->zp_mode);

        switch (vp->v_type) {
        case VDIR:
                if (zp->z_phys->zp_flags & ZFS_XATTR) {
                        vn_setops(vp, zfs_xdvnodeops);
                        vp->v_flag |= V_XATTRDIR;
                } else {
                        vn_setops(vp, zfs_dvnodeops);
                }
                zp->z_zn_prefetch = B_TRUE; /* z_prefetch default is enabled */
                break;
        case VBLK:
        case VCHR:
                vp->v_rdev = zfs_cmpldev(zp->z_phys->zp_rdev);
                /*FALLTHROUGH*/
        case VFIFO:
        case VSOCK:
        case VDOOR:
                vn_setops(vp, zfs_fvnodeops);
                break;
        case VREG:
                vp->v_flag |= VMODSORT;
                if (zp->z_phys->zp_parent == zfsvfs->z_shares_dir)
                        vn_setops(vp, zfs_sharevnodeops);
                else
                        vn_setops(vp, zfs_fvnodeops);
                break;
        case VLNK:
                vn_setops(vp, zfs_symvnodeops);
                break;
        default:
                vn_setops(vp, zfs_evnodeops);
                break;
        }

        mutex_enter(&zfsvfs->z_znodes_lock);
        list_insert_tail(&zfsvfs->z_all_znodes, zp);
        membar_producer();
        /*
         * Everything else must be valid before assigning z_zfsvfs makes the
         * znode eligible for zfs_znode_move().
         */
        zp->z_zfsvfs = zfsvfs;
        mutex_exit(&zfsvfs->z_znodes_lock);

        VFS_HOLD(zfsvfs->z_vfs);
        return (zp);
}

/*
 * Create a new DMU object to hold a zfs znode.
 *
 *      IN:     dzp     - parent directory for new znode
 *              vap     - file attributes for new znode
 *              tx      - dmu transaction id for zap operations
 *              cr      - credentials of caller
 *              flag    - flags:
 *                        IS_ROOT_NODE  - new object will be root
 *                        IS_XATTR      - new object is an attribute
 *                        IS_REPLAY     - intent log replay
 *              bonuslen - length of bonus buffer
 *              setaclp  - File/Dir initial ACL
 *              fuidp    - Tracks fuid allocation.
 *
 *      OUT:    zpp     - allocated znode
 *
 */
void
zfs_mknode(znode_t *dzp, vattr_t *vap, dmu_tx_t *tx, cred_t *cr,
    uint_t flag, znode_t **zpp, int bonuslen, zfs_acl_ids_t *acl_ids)
{
        dmu_buf_t       *db;
        znode_phys_t    *pzp;
        zfsvfs_t        *zfsvfs = dzp->z_zfsvfs;
        timestruc_t     now;
        uint64_t        gen, obj;
        int             err;

        ASSERT(vap && (vap->va_mask & (AT_TYPE|AT_MODE)) == (AT_TYPE|AT_MODE));

        if (zfsvfs->z_replay) {
                obj = vap->va_nodeid;
                flag |= IS_REPLAY;
                now = vap->va_ctime;            /* see zfs_replay_create() */
                gen = vap->va_nblocks;          /* ditto */
        } else {
                obj = 0;
                gethrestime(&now);
                gen = dmu_tx_get_txg(tx);
        }

        /*
         * Create a new DMU object.
         */
        /*
         * There's currently no mechanism for pre-reading the blocks that will
         * be to needed allocate a new object, so we accept the small chance
         * that there will be an i/o error and we will fail one of the
         * assertions below.
         */
        if (vap->va_type == VDIR) {
                if (flag & IS_REPLAY) {
                        err = zap_create_claim_norm(zfsvfs->z_os, obj,
                            zfsvfs->z_norm, DMU_OT_DIRECTORY_CONTENTS,
                            DMU_OT_ZNODE, sizeof (znode_phys_t) + bonuslen, tx);
                        ASSERT3U(err, ==, 0);
                } else {
                        obj = zap_create_norm(zfsvfs->z_os,
                            zfsvfs->z_norm, DMU_OT_DIRECTORY_CONTENTS,
                            DMU_OT_ZNODE, sizeof (znode_phys_t) + bonuslen, tx);
                }
        } else {
                if (flag & IS_REPLAY) {
                        err = dmu_object_claim(zfsvfs->z_os, obj,
                            DMU_OT_PLAIN_FILE_CONTENTS, 0,
                            DMU_OT_ZNODE, sizeof (znode_phys_t) + bonuslen, tx);
                        ASSERT3U(err, ==, 0);
                } else {
                        obj = dmu_object_alloc(zfsvfs->z_os,
                            DMU_OT_PLAIN_FILE_CONTENTS, 0,
                            DMU_OT_ZNODE, sizeof (znode_phys_t) + bonuslen, tx);
                }
        }
        VERIFY(0 == dmu_bonus_hold(zfsvfs->z_os, obj, NULL, &db));
        dmu_buf_will_dirty(db, tx);

        /*
         * Initialize the znode physical data to zero.
         */
        ASSERT(db->db_size >= sizeof (znode_phys_t));
        bzero(db->db_data, db->db_size);
        pzp = db->db_data;

        /*
         * If this is the root, fix up the half-initialized parent pointer
         * to reference the just-allocated physical data area.
         */
        if (flag & IS_ROOT_NODE) {
                dzp->z_dbuf = db;
                dzp->z_phys = pzp;
                dzp->z_id = obj;
        }

        /*
         * If parent is an xattr, so am I.
         */
        if (dzp->z_phys->zp_flags & ZFS_XATTR)
                flag |= IS_XATTR;

        if (vap->va_type == VBLK || vap->va_type == VCHR) {
                pzp->zp_rdev = zfs_expldev(vap->va_rdev);
        }

        if (zfsvfs->z_use_fuids)
                pzp->zp_flags = ZFS_ARCHIVE | ZFS_AV_MODIFIED;

        if (vap->va_type == VDIR) {
                pzp->zp_size = 2;               /* contents ("." and "..") */
                pzp->zp_links = (flag & (IS_ROOT_NODE | IS_XATTR)) ? 2 : 1;
        }

        pzp->zp_parent = dzp->z_id;
        if (flag & IS_XATTR)
                pzp->zp_flags |= ZFS_XATTR;

        pzp->zp_gen = gen;

        ZFS_TIME_ENCODE(&now, pzp->zp_crtime);
        ZFS_TIME_ENCODE(&now, pzp->zp_ctime);

        if (vap->va_mask & AT_ATIME) {
                ZFS_TIME_ENCODE(&vap->va_atime, pzp->zp_atime);
        } else {
                ZFS_TIME_ENCODE(&now, pzp->zp_atime);
        }

        if (vap->va_mask & AT_MTIME) {
                ZFS_TIME_ENCODE(&vap->va_mtime, pzp->zp_mtime);
        } else {
                ZFS_TIME_ENCODE(&now, pzp->zp_mtime);
        }

        pzp->zp_mode = MAKEIMODE(vap->va_type, vap->va_mode);
        if (!(flag & IS_ROOT_NODE)) {
                ZFS_OBJ_HOLD_ENTER(zfsvfs, obj);
                *zpp = zfs_znode_alloc(zfsvfs, db, 0);
                ZFS_OBJ_HOLD_EXIT(zfsvfs, obj);
        } else {
                /*
                 * If we are creating the root node, the "parent" we
                 * passed in is the znode for the root.
                 */
                *zpp = dzp;
        }
        pzp->zp_uid = acl_ids->z_fuid;
        pzp->zp_gid = acl_ids->z_fgid;
        pzp->zp_mode = acl_ids->z_mode;
        VERIFY(0 == zfs_aclset_common(*zpp, acl_ids->z_aclp, cr, tx));
        if (vap->va_mask & AT_XVATTR)
                zfs_xvattr_set(*zpp, (xvattr_t *)vap);
}

void
zfs_xvattr_set(znode_t *zp, xvattr_t *xvap)
{
        xoptattr_t *xoap;

        xoap = xva_getxoptattr(xvap);
        ASSERT(xoap);

        if (XVA_ISSET_REQ(xvap, XAT_CREATETIME)) {
                ZFS_TIME_ENCODE(&xoap->xoa_createtime, zp->z_phys->zp_crtime);
                XVA_SET_RTN(xvap, XAT_CREATETIME);
        }
        if (XVA_ISSET_REQ(xvap, XAT_READONLY)) {
                ZFS_ATTR_SET(zp, ZFS_READONLY, xoap->xoa_readonly);
                XVA_SET_RTN(xvap, XAT_READONLY);
        }
        if (XVA_ISSET_REQ(xvap, XAT_HIDDEN)) {
                ZFS_ATTR_SET(zp, ZFS_HIDDEN, xoap->xoa_hidden);
                XVA_SET_RTN(xvap, XAT_HIDDEN);
        }
        if (XVA_ISSET_REQ(xvap, XAT_SYSTEM)) {
                ZFS_ATTR_SET(zp, ZFS_SYSTEM, xoap->xoa_system);
                XVA_SET_RTN(xvap, XAT_SYSTEM);
        }
        if (XVA_ISSET_REQ(xvap, XAT_ARCHIVE)) {
                ZFS_ATTR_SET(zp, ZFS_ARCHIVE, xoap->xoa_archive);
                XVA_SET_RTN(xvap, XAT_ARCHIVE);
        }
        if (XVA_ISSET_REQ(xvap, XAT_IMMUTABLE)) {
                ZFS_ATTR_SET(zp, ZFS_IMMUTABLE, xoap->xoa_immutable);
                XVA_SET_RTN(xvap, XAT_IMMUTABLE);
        }
        if (XVA_ISSET_REQ(xvap, XAT_NOUNLINK)) {
                ZFS_ATTR_SET(zp, ZFS_NOUNLINK, xoap->xoa_nounlink);
                XVA_SET_RTN(xvap, XAT_NOUNLINK);
        }
        if (XVA_ISSET_REQ(xvap, XAT_APPENDONLY)) {
                ZFS_ATTR_SET(zp, ZFS_APPENDONLY, xoap->xoa_appendonly);
                XVA_SET_RTN(xvap, XAT_APPENDONLY);
        }
        if (XVA_ISSET_REQ(xvap, XAT_NODUMP)) {
                ZFS_ATTR_SET(zp, ZFS_NODUMP, xoap->xoa_nodump);
                XVA_SET_RTN(xvap, XAT_NODUMP);
        }
        if (XVA_ISSET_REQ(xvap, XAT_OPAQUE)) {
                ZFS_ATTR_SET(zp, ZFS_OPAQUE, xoap->xoa_opaque);
                XVA_SET_RTN(xvap, XAT_OPAQUE);
        }
        if (XVA_ISSET_REQ(xvap, XAT_AV_QUARANTINED)) {
                ZFS_ATTR_SET(zp, ZFS_AV_QUARANTINED,
                    xoap->xoa_av_quarantined);
                XVA_SET_RTN(xvap, XAT_AV_QUARANTINED);
        }
        if (XVA_ISSET_REQ(xvap, XAT_AV_MODIFIED)) {
                ZFS_ATTR_SET(zp, ZFS_AV_MODIFIED, xoap->xoa_av_modified);
                XVA_SET_RTN(xvap, XAT_AV_MODIFIED);
        }
        if (XVA_ISSET_REQ(xvap, XAT_AV_SCANSTAMP)) {
                (void) memcpy(zp->z_phys + 1, xoap->xoa_av_scanstamp,
                    sizeof (xoap->xoa_av_scanstamp));
                zp->z_phys->zp_flags |= ZFS_BONUS_SCANSTAMP;
                XVA_SET_RTN(xvap, XAT_AV_SCANSTAMP);
        }
}

int
zfs_zget(zfsvfs_t *zfsvfs, uint64_t obj_num, znode_t **zpp)
{
        dmu_object_info_t doi;
        dmu_buf_t       *db;
        znode_t         *zp;
        int err;

        *zpp = NULL;

        ZFS_OBJ_HOLD_ENTER(zfsvfs, obj_num);

        err = dmu_bonus_hold(zfsvfs->z_os, obj_num, NULL, &db);
        if (err) {
                ZFS_OBJ_HOLD_EXIT(zfsvfs, obj_num);
                return (err);
        }

        dmu_object_info_from_db(db, &doi);
        if (doi.doi_bonus_type != DMU_OT_ZNODE ||
            doi.doi_bonus_size < sizeof (znode_phys_t)) {
                dmu_buf_rele(db, NULL);
                ZFS_OBJ_HOLD_EXIT(zfsvfs, obj_num);
                return (EINVAL);
        }

        zp = dmu_buf_get_user(db);
        if (zp != NULL) {
                mutex_enter(&zp->z_lock);

                /*
                 * Since we do immediate eviction of the z_dbuf, we
                 * should never find a dbuf with a znode that doesn't
                 * know about the dbuf.
                 */
                ASSERT3P(zp->z_dbuf, ==, db);
                ASSERT3U(zp->z_id, ==, obj_num);
                if (zp->z_unlinked) {
                        err = ENOENT;
                } else {
                        VN_HOLD(ZTOV(zp));
                        *zpp = zp;
                        err = 0;
                }
                dmu_buf_rele(db, NULL);
                mutex_exit(&zp->z_lock);
                ZFS_OBJ_HOLD_EXIT(zfsvfs, obj_num);
                return (err);
        }

        /*
         * Not found create new znode/vnode
         */
        zp = zfs_znode_alloc(zfsvfs, db, doi.doi_data_block_size);
        ZFS_OBJ_HOLD_EXIT(zfsvfs, obj_num);
        *zpp = zp;
        return (0);
}

int
zfs_rezget(znode_t *zp)
{
        zfsvfs_t *zfsvfs = zp->z_zfsvfs;
        dmu_object_info_t doi;
        dmu_buf_t *db;
        uint64_t obj_num = zp->z_id;
        int err;

        ZFS_OBJ_HOLD_ENTER(zfsvfs, obj_num);

        err = dmu_bonus_hold(zfsvfs->z_os, obj_num, NULL, &db);
        if (err) {
                ZFS_OBJ_HOLD_EXIT(zfsvfs, obj_num);
                return (err);
        }

        dmu_object_info_from_db(db, &doi);
        if (doi.doi_bonus_type != DMU_OT_ZNODE ||
            doi.doi_bonus_size < sizeof (znode_phys_t)) {
                dmu_buf_rele(db, NULL);
                ZFS_OBJ_HOLD_EXIT(zfsvfs, obj_num);
                return (EINVAL);
        }

        if (((znode_phys_t *)db->db_data)->zp_gen != zp->z_gen) {
                dmu_buf_rele(db, NULL);
                ZFS_OBJ_HOLD_EXIT(zfsvfs, obj_num);
                return (EIO);
        }

        zfs_znode_dmu_init(zfsvfs, zp, db);
        zp->z_unlinked = (zp->z_phys->zp_links == 0);
        zp->z_blksz = doi.doi_data_block_size;

        ZFS_OBJ_HOLD_EXIT(zfsvfs, obj_num);

        return (0);
}

void
zfs_znode_delete(znode_t *zp, dmu_tx_t *tx)
{
        zfsvfs_t *zfsvfs = zp->z_zfsvfs;
        objset_t *os = zfsvfs->z_os;
        uint64_t obj = zp->z_id;
        uint64_t acl_obj = zp->z_phys->zp_acl.z_acl_extern_obj;

        ZFS_OBJ_HOLD_ENTER(zfsvfs, obj);
        if (acl_obj)
                VERIFY(0 == dmu_object_free(os, acl_obj, tx));
        VERIFY(0 == dmu_object_free(os, obj, tx));
        zfs_znode_dmu_fini(zp);
        ZFS_OBJ_HOLD_EXIT(zfsvfs, obj);
        zfs_znode_free(zp);
}

void
zfs_zinactive(znode_t *zp)
{
        vnode_t *vp = ZTOV(zp);
        zfsvfs_t *zfsvfs = zp->z_zfsvfs;
        uint64_t z_id = zp->z_id;

        ASSERT(zp->z_dbuf && zp->z_phys);

        /*
         * Don't allow a zfs_zget() while were trying to release this znode
         */
        ZFS_OBJ_HOLD_ENTER(zfsvfs, z_id);

        mutex_enter(&zp->z_lock);
        mutex_enter(&vp->v_lock);
        vp->v_count--;
        if (vp->v_count > 0 || vn_has_cached_data(vp)) {
                /*
                 * If the hold count is greater than zero, somebody has
                 * obtained a new reference on this znode while we were
                 * processing it here, so we are done.  If we still have
                 * mapped pages then we are also done, since we don't
                 * want to inactivate the znode until the pages get pushed.
                 *
                 * XXX - if vn_has_cached_data(vp) is true, but count == 0,
                 * this seems like it would leave the znode hanging with
                 * no chance to go inactive...
                 */
                mutex_exit(&vp->v_lock);
                mutex_exit(&zp->z_lock);
                ZFS_OBJ_HOLD_EXIT(zfsvfs, z_id);
                return;
        }
        mutex_exit(&vp->v_lock);

        /*
         * If this was the last reference to a file with no links,
         * remove the file from the file system.
         */
        if (zp->z_unlinked) {
                mutex_exit(&zp->z_lock);
                ZFS_OBJ_HOLD_EXIT(zfsvfs, z_id);
                zfs_rmnode(zp);
                return;
        }
        mutex_exit(&zp->z_lock);
        zfs_znode_dmu_fini(zp);
        ZFS_OBJ_HOLD_EXIT(zfsvfs, z_id);
        zfs_znode_free(zp);
}

void
zfs_znode_free(znode_t *zp)
{
        zfsvfs_t *zfsvfs = zp->z_zfsvfs;

        vn_invalid(ZTOV(zp));

        ASSERT(ZTOV(zp)->v_count == 0);

        mutex_enter(&zfsvfs->z_znodes_lock);
        POINTER_INVALIDATE(&zp->z_zfsvfs);
        list_remove(&zfsvfs->z_all_znodes, zp);
        mutex_exit(&zfsvfs->z_znodes_lock);

        if (zp->z_acl_cached) {
                zfs_acl_free(zp->z_acl_cached);
                zp->z_acl_cached = NULL;
        }

        kmem_cache_free(znode_cache, zp);

        VFS_RELE(zfsvfs->z_vfs);
}

void
zfs_time_stamper_locked(znode_t *zp, uint_t flag, dmu_tx_t *tx)
{
        timestruc_t     now;

        ASSERT(MUTEX_HELD(&zp->z_lock));

        gethrestime(&now);

        if (tx) {
                dmu_buf_will_dirty(zp->z_dbuf, tx);
                zp->z_atime_dirty = 0;
                zp->z_seq++;
        } else {
                zp->z_atime_dirty = 1;
        }

        if (flag & AT_ATIME)
                ZFS_TIME_ENCODE(&now, zp->z_phys->zp_atime);

        if (flag & AT_MTIME) {
                ZFS_TIME_ENCODE(&now, zp->z_phys->zp_mtime);
                if (zp->z_zfsvfs->z_use_fuids)
                        zp->z_phys->zp_flags |= (ZFS_ARCHIVE | ZFS_AV_MODIFIED);
        }

        if (flag & AT_CTIME) {
                ZFS_TIME_ENCODE(&now, zp->z_phys->zp_ctime);
                if (zp->z_zfsvfs->z_use_fuids)
                        zp->z_phys->zp_flags |= ZFS_ARCHIVE;
        }
}

/*
 * Update the requested znode timestamps with the current time.
 * If we are in a transaction, then go ahead and mark the znode
 * dirty in the transaction so the timestamps will go to disk.
 * Otherwise, we will get pushed next time the znode is updated
 * in a transaction, or when this znode eventually goes inactive.
 *
 * Why is this OK?
 *  1 - Only the ACCESS time is ever updated outside of a transaction.
 *  2 - Multiple consecutive updates will be collapsed into a single
 *      znode update by the transaction grouping semantics of the DMU.
 */
void
zfs_time_stamper(znode_t *zp, uint_t flag, dmu_tx_t *tx)
{
        mutex_enter(&zp->z_lock);
        zfs_time_stamper_locked(zp, flag, tx);
        mutex_exit(&zp->z_lock);
}

/*
 * Grow the block size for a file.
 *
 *      IN:     zp      - znode of file to free data in.
 *              size    - requested block size
 *              tx      - open transaction.
 *
 * NOTE: this function assumes that the znode is write locked.
 */
void
zfs_grow_blocksize(znode_t *zp, uint64_t size, dmu_tx_t *tx)
{
        int             error;
        u_longlong_t    dummy;

        if (size <= zp->z_blksz)
                return;
        /*
         * If the file size is already greater than the current blocksize,
         * we will not grow.  If there is more than one block in a file,
         * the blocksize cannot change.
         */
        if (zp->z_blksz && zp->z_phys->zp_size > zp->z_blksz)
                return;

        error = dmu_object_set_blocksize(zp->z_zfsvfs->z_os, zp->z_id,
            size, 0, tx);
        if (error == ENOTSUP)
                return;
        ASSERT3U(error, ==, 0);

        /* What blocksize did we actually get? */
        dmu_object_size_from_db(zp->z_dbuf, &zp->z_blksz, &dummy);
}

/*
 * This is a dummy interface used when pvn_vplist_dirty() should *not*
 * be calling back into the fs for a putpage().  E.g.: when truncating
 * a file, the pages being "thrown away* don't need to be written out.
 */
/* ARGSUSED */
static int
zfs_no_putpage(vnode_t *vp, page_t *pp, u_offset_t *offp, size_t *lenp,
    int flags, cred_t *cr)
{
        ASSERT(0);
        return (0);
}

/*
 * Increase the file length
 *
 *      IN:     zp      - znode of file to free data in.
 *              end     - new end-of-file
 *
 *      RETURN: 0 if success
 *              error code if failure
 */
static int
zfs_extend(znode_t *zp, uint64_t end)
{
        zfsvfs_t *zfsvfs = zp->z_zfsvfs;
        dmu_tx_t *tx;
        rl_t *rl;
        uint64_t newblksz;
        int error;

        /*
         * We will change zp_size, lock the whole file.
         */
        rl = zfs_range_lock(zp, 0, UINT64_MAX, RL_WRITER);

        /*
         * Nothing to do if file already at desired length.
         */
        if (end <= zp->z_phys->zp_size) {
                zfs_range_unlock(rl);
                return (0);
        }
top:
        tx = dmu_tx_create(zfsvfs->z_os);
        dmu_tx_hold_bonus(tx, zp->z_id);
        if (end > zp->z_blksz &&
            (!ISP2(zp->z_blksz) || zp->z_blksz < zfsvfs->z_max_blksz)) {
                /*
                 * We are growing the file past the current block size.
                 */
                if (zp->z_blksz > zp->z_zfsvfs->z_max_blksz) {
                        ASSERT(!ISP2(zp->z_blksz));
                        newblksz = MIN(end, SPA_MAXBLOCKSIZE);
                } else {
                        newblksz = MIN(end, zp->z_zfsvfs->z_max_blksz);
                }
                dmu_tx_hold_write(tx, zp->z_id, 0, newblksz);
        } else {
                newblksz = 0;
        }

        error = dmu_tx_assign(tx, TXG_NOWAIT);
        if (error) {
                if (error == ERESTART) {
                        dmu_tx_wait(tx);
                        dmu_tx_abort(tx);
                        goto top;
                }
                dmu_tx_abort(tx);
                zfs_range_unlock(rl);
                return (error);
        }
        dmu_buf_will_dirty(zp->z_dbuf, tx);

        if (newblksz)
                zfs_grow_blocksize(zp, newblksz, tx);

        zp->z_phys->zp_size = end;

        zfs_range_unlock(rl);

        dmu_tx_commit(tx);

        return (0);
}

/*
 * Free space in a file.
 *
 *      IN:     zp      - znode of file to free data in.
 *              off     - start of section to free.
 *              len     - length of section to free.
 *
 *      RETURN: 0 if success
 *              error code if failure
 */
static int
zfs_free_range(znode_t *zp, uint64_t off, uint64_t len)
{
        zfsvfs_t *zfsvfs = zp->z_zfsvfs;
        rl_t *rl;
        int error;

        /*
         * Lock the range being freed.
         */
        rl = zfs_range_lock(zp, off, len, RL_WRITER);

        /*
         * Nothing to do if file already at desired length.
         */
        if (off >= zp->z_phys->zp_size) {
                zfs_range_unlock(rl);
                return (0);
        }

        if (off + len > zp->z_phys->zp_size)
                len = zp->z_phys->zp_size - off;

        error = dmu_free_long_range(zfsvfs->z_os, zp->z_id, off, len);

        zfs_range_unlock(rl);

        return (error);
}

/*
 * Truncate a file
 *
 *      IN:     zp      - znode of file to free data in.
 *              end     - new end-of-file.
 *
 *      RETURN: 0 if success
 *              error code if failure
 */
static int
zfs_trunc(znode_t *zp, uint64_t end)
{
        zfsvfs_t *zfsvfs = zp->z_zfsvfs;
        vnode_t *vp = ZTOV(zp);
        dmu_tx_t *tx;
        rl_t *rl;
        int error;

        /*
         * We will change zp_size, lock the whole file.
         */
        rl = zfs_range_lock(zp, 0, UINT64_MAX, RL_WRITER);

        /*
         * Nothing to do if file already at desired length.
         */
        if (end >= zp->z_phys->zp_size) {
                zfs_range_unlock(rl);
                return (0);
        }

        error = dmu_free_long_range(zfsvfs->z_os, zp->z_id, end,  -1);
        if (error) {
                zfs_range_unlock(rl);
                return (error);
        }
top:
        tx = dmu_tx_create(zfsvfs->z_os);
        dmu_tx_hold_bonus(tx, zp->z_id);
        error = dmu_tx_assign(tx, TXG_NOWAIT);
        if (error) {
                if (error == ERESTART) {
                        dmu_tx_wait(tx);
                        dmu_tx_abort(tx);
                        goto top;
                }
                dmu_tx_abort(tx);
                zfs_range_unlock(rl);
                return (error);
        }
        dmu_buf_will_dirty(zp->z_dbuf, tx);

        zp->z_phys->zp_size = end;

        dmu_tx_commit(tx);

        /*
         * Clear any mapped pages in the truncated region.  This has to
         * happen outside of the transaction to avoid the possibility of
         * a deadlock with someone trying to push a page that we are
         * about to invalidate.
         */
        if (vn_has_cached_data(vp)) {
                page_t *pp;
                uint64_t start = end & PAGEMASK;
                int poff = end & PAGEOFFSET;

                if (poff != 0 && (pp = page_lookup(vp, start, SE_SHARED))) {
                        /*
                         * We need to zero a partial page.
                         */
                        pagezero(pp, poff, PAGESIZE - poff);
                        start += PAGESIZE;
                        page_unlock(pp);
                }
                error = pvn_vplist_dirty(vp, start, zfs_no_putpage,
                    B_INVAL | B_TRUNC, NULL);
                ASSERT(error == 0);
        }

        zfs_range_unlock(rl);

        return (0);
}

/*
 * Free space in a file
 *
 *      IN:     zp      - znode of file to free data in.
 *              off     - start of range
 *              len     - end of range (0 => EOF)
 *              flag    - current file open mode flags.
 *              log     - TRUE if this action should be logged
 *
 *      RETURN: 0 if success
 *              error code if failure
 */
int
zfs_freesp(znode_t *zp, uint64_t off, uint64_t len, int flag, boolean_t log)
{
        vnode_t *vp = ZTOV(zp);
        dmu_tx_t *tx;
        zfsvfs_t *zfsvfs = zp->z_zfsvfs;
        zilog_t *zilog = zfsvfs->z_log;
        int error;

        if (off > zp->z_phys->zp_size) {
                error =  zfs_extend(zp, off+len);
                if (error == 0 && log)
                        goto log;
                else
                        return (error);
        }

        /*
         * Check for any locks in the region to be freed.
         */
        if (MANDLOCK(vp, (mode_t)zp->z_phys->zp_mode)) {
                uint64_t length = (len ? len : zp->z_phys->zp_size - off);
                if (error = chklock(vp, FWRITE, off, length, flag, NULL))
                        return (error);
        }

        if (len == 0) {
                error = zfs_trunc(zp, off);
        } else {
                if ((error = zfs_free_range(zp, off, len)) == 0 &&
                    off + len > zp->z_phys->zp_size)
                        error = zfs_extend(zp, off+len);
        }
        if (error || !log)
                return (error);
log:
        tx = dmu_tx_create(zfsvfs->z_os);
        dmu_tx_hold_bonus(tx, zp->z_id);
        error = dmu_tx_assign(tx, TXG_NOWAIT);
        if (error) {
                if (error == ERESTART) {
                        dmu_tx_wait(tx);
                        dmu_tx_abort(tx);
                        goto log;
                }
                dmu_tx_abort(tx);
                return (error);
        }

        zfs_time_stamper(zp, CONTENT_MODIFIED, tx);
        zfs_log_truncate(zilog, tx, TX_TRUNCATE, zp, off, len);

        dmu_tx_commit(tx);
        return (0);
}

void
zfs_create_fs(objset_t *os, cred_t *cr, nvlist_t *zplprops, dmu_tx_t *tx)
{
        zfsvfs_t        zfsvfs;
        uint64_t        moid, obj, version;
        uint64_t        sense = ZFS_CASE_SENSITIVE;
        uint64_t        norm = 0;
        nvpair_t        *elem;
        int             error;
        znode_t         *rootzp = NULL;
        vnode_t         *vp;
        vattr_t         vattr;
        znode_t         *zp;
        zfs_acl_ids_t   acl_ids;

        /*
         * First attempt to create master node.
         */
        /*
         * In an empty objset, there are no blocks to read and thus
         * there can be no i/o errors (which we assert below).
         */
        moid = MASTER_NODE_OBJ;
        error = zap_create_claim(os, moid, DMU_OT_MASTER_NODE,
            DMU_OT_NONE, 0, tx);
        ASSERT(error == 0);

        /*
         * Set starting attributes.
         */
        if (spa_version(dmu_objset_spa(os)) >= SPA_VERSION_USERSPACE)
                version = ZPL_VERSION;
        else if (spa_version(dmu_objset_spa(os)) >= SPA_VERSION_FUID)
                version = ZPL_VERSION_USERSPACE - 1;
        else
                version = ZPL_VERSION_FUID - 1;
        elem = NULL;
        while ((elem = nvlist_next_nvpair(zplprops, elem)) != NULL) {
                /* For the moment we expect all zpl props to be uint64_ts */
                uint64_t val;
                char *name;

                ASSERT(nvpair_type(elem) == DATA_TYPE_UINT64);
                VERIFY(nvpair_value_uint64(elem, &val) == 0);
                name = nvpair_name(elem);
                if (strcmp(name, zfs_prop_to_name(ZFS_PROP_VERSION)) == 0) {
                        if (val < version)
                                version = val;
                } else {
                        error = zap_update(os, moid, name, 8, 1, &val, tx);
                }
                ASSERT(error == 0);
                if (strcmp(name, zfs_prop_to_name(ZFS_PROP_NORMALIZE)) == 0)
                        norm = val;
                else if (strcmp(name, zfs_prop_to_name(ZFS_PROP_CASE)) == 0)
                        sense = val;
        }
        ASSERT(version != 0);
        error = zap_update(os, moid, ZPL_VERSION_STR, 8, 1, &version, tx);

        /*
         * Create a delete queue.
         */
        obj = zap_create(os, DMU_OT_UNLINKED_SET, DMU_OT_NONE, 0, tx);

        error = zap_add(os, moid, ZFS_UNLINKED_SET, 8, 1, &obj, tx);
        ASSERT(error == 0);

        /*
         * Create root znode.  Create minimal znode/vnode/zfsvfs
         * to allow zfs_mknode to work.
         */
        vattr.va_mask = AT_MODE|AT_UID|AT_GID|AT_TYPE;
        vattr.va_type = VDIR;
        vattr.va_mode = S_IFDIR|0755;
        vattr.va_uid = crgetuid(cr);
        vattr.va_gid = crgetgid(cr);

        rootzp = kmem_cache_alloc(znode_cache, KM_SLEEP);
        rootzp->z_unlinked = 0;
        rootzp->z_atime_dirty = 0;

        vp = ZTOV(rootzp);
        vn_reinit(vp);
        vp->v_type = VDIR;

        bzero(&zfsvfs, sizeof (zfsvfs_t));

        zfsvfs.z_os = os;
        zfsvfs.z_parent = &zfsvfs;
        zfsvfs.z_version = version;
        zfsvfs.z_use_fuids = USE_FUIDS(version, os);
        zfsvfs.z_norm = norm;
        /*
         * Fold case on file systems that are always or sometimes case
         * insensitive.
         */
        if (sense == ZFS_CASE_INSENSITIVE || sense == ZFS_CASE_MIXED)
                zfsvfs.z_norm |= U8_TEXTPREP_TOUPPER;

        mutex_init(&zfsvfs.z_znodes_lock, NULL, MUTEX_DEFAULT, NULL);
        list_create(&zfsvfs.z_all_znodes, sizeof (znode_t),
            offsetof(znode_t, z_link_node));

        ASSERT(!POINTER_IS_VALID(rootzp->z_zfsvfs));
        rootzp->z_zfsvfs = &zfsvfs;
        VERIFY(0 == zfs_acl_ids_create(rootzp, IS_ROOT_NODE, &vattr,
            cr, NULL, &acl_ids));
        zfs_mknode(rootzp, &vattr, tx, cr, IS_ROOT_NODE, &zp, 0, &acl_ids);
        ASSERT3P(zp, ==, rootzp);
        ASSERT(!vn_in_dnlc(ZTOV(rootzp))); /* not valid to move */
        error = zap_add(os, moid, ZFS_ROOT_OBJ, 8, 1, &rootzp->z_id, tx);
        ASSERT(error == 0);
        zfs_acl_ids_free(&acl_ids);
        POINTER_INVALIDATE(&rootzp->z_zfsvfs);

        ZTOV(rootzp)->v_count = 0;
        dmu_buf_rele(rootzp->z_dbuf, NULL);
        rootzp->z_dbuf = NULL;
        kmem_cache_free(znode_cache, rootzp);

        /*
         * Create shares directory
         */

        error = zfs_create_share_dir(&zfsvfs, tx);

        ASSERT(error == 0);
}

#endif /* _KERNEL */
/*
 * Given an object number, return its parent object number and whether
 * or not the object is an extended attribute directory.
 */
static int
zfs_obj_to_pobj(objset_t *osp, uint64_t obj, uint64_t *pobjp, int *is_xattrdir)
{
        dmu_buf_t *db;
        dmu_object_info_t doi;
        znode_phys_t *zp;
        int error;

        if ((error = dmu_bonus_hold(osp, obj, FTAG, &db)) != 0)
                return (error);

        dmu_object_info_from_db(db, &doi);
        if (doi.doi_bonus_type != DMU_OT_ZNODE ||
            doi.doi_bonus_size < sizeof (znode_phys_t)) {
                dmu_buf_rele(db, FTAG);
                return (EINVAL);
        }

        zp = db->db_data;
        *pobjp = zp->zp_parent;
        *is_xattrdir = ((zp->zp_flags & ZFS_XATTR) != 0) &&
            S_ISDIR(zp->zp_mode);
        dmu_buf_rele(db, FTAG);

        return (0);
}

int
zfs_obj_to_path(objset_t *osp, uint64_t obj, char *buf, int len)
{
        char *path = buf + len - 1;
        int error;

        *path = '\0';

        for (;;) {
                uint64_t pobj;
                char component[MAXNAMELEN + 2];
                size_t complen;
                int is_xattrdir;

                if ((error = zfs_obj_to_pobj(osp, obj, &pobj,
                    &is_xattrdir)) != 0)
                        break;

                if (pobj == obj) {
                        if (path[0] != '/')
                                *--path = '/';
                        break;
                }

                component[0] = '/';
                if (is_xattrdir) {
                        (void) sprintf(component + 1, "<xattrdir>");
                } else {
                        error = zap_value_search(osp, pobj, obj,
                            ZFS_DIRENT_OBJ(-1ULL), component + 1);
                        if (error != 0)
                                break;
                }

                complen = strlen(component);
                path -= complen;
                ASSERT(path >= buf);
                bcopy(component, path, complen);
                obj = pobj;
        }

        if (error == 0)
                (void) memmove(buf, path, buf + len - path);
        return (error);
}