Fletcher4: Incremental updates and ctx calculation

[mirror_zfs.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 (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
 * Copyright (c) 2012, 2014 by Delphix. All rights reserved.
 */

/* 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/zfs_vnops.h>
#include <sys/zfs_ctldir.h>
#include <sys/dnode.h>
#include <sys/fs/zfs.h>
#include <sys/kidmap.h>
#include <sys/zpl.h>
#endif /* _KERNEL */

#include <sys/dmu.h>
#include <sys/dmu_objset.h>
#include <sys/dmu_tx.h>
#include <sys/refcount.h>
#include <sys/stat.h>
#include <sys/zap.h>
#include <sys/zfs_znode.h>
#include <sys/sa.h>
#include <sys/zfs_sa.h>
#include <sys/zfs_stat.h>

#include "zfs_prop.h"
#include "zfs_comutil.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 */

/*
 * 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

static kmem_cache_t *znode_cache = NULL;
static kmem_cache_t *znode_hold_cache = NULL;
unsigned int zfs_object_mutex_size = ZFS_OBJ_MTX_SZ;

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

        inode_init_once(ZTOI(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_NOLOCKDEP, NULL);
        mutex_init(&zp->z_acl_lock, NULL, MUTEX_DEFAULT, NULL);
        rw_init(&zp->z_xattr_lock, NULL, RW_DEFAULT, NULL);

        zfs_rlock_init(&zp->z_range_lock);

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

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

        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);
        rw_destroy(&zp->z_xattr_lock);
        zfs_rlock_destroy(&zp->z_range_lock);

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

static int
zfs_znode_hold_cache_constructor(void *buf, void *arg, int kmflags)
{
        znode_hold_t *zh = buf;

        mutex_init(&zh->zh_lock, NULL, MUTEX_DEFAULT, NULL);
        refcount_create(&zh->zh_refcount);
        zh->zh_obj = ZFS_NO_OBJECT;

        return (0);
}

static void
zfs_znode_hold_cache_destructor(void *buf, void *arg)
{
        znode_hold_t *zh = buf;

        mutex_destroy(&zh->zh_lock);
        refcount_destroy(&zh->zh_refcount);
}

void
zfs_znode_init(void)
{
        /*
         * Initialize zcache.  The KMC_SLAB hint is used in order that it be
         * backed by kmalloc() when on the Linux slab in order that any
         * wait_on_bit() operations on the related inode operate properly.
         */
        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, KMC_SLAB);

        ASSERT(znode_hold_cache == NULL);
        znode_hold_cache = kmem_cache_create("zfs_znode_hold_cache",
            sizeof (znode_hold_t), 0, zfs_znode_hold_cache_constructor,
            zfs_znode_hold_cache_destructor, NULL, NULL, NULL, 0);
}

void
zfs_znode_fini(void)
{
        /*
         * Cleanup zcache
         */
        if (znode_cache)
                kmem_cache_destroy(znode_cache);
        znode_cache = NULL;

        if (znode_hold_cache)
                kmem_cache_destroy(znode_hold_cache);
        znode_hold_cache = NULL;
}

/*
 * The zfs_znode_hold_enter() / zfs_znode_hold_exit() functions are used to
 * serialize access to a znode and its SA buffer while the object is being
 * created or destroyed.  This kind of locking would normally reside in the
 * znode itself but in this case that's impossible because the znode and SA
 * buffer may not yet exist.  Therefore the locking is handled externally
 * with an array of mutexs and AVLs trees which contain per-object locks.
 *
 * In zfs_znode_hold_enter() a per-object lock is created as needed, inserted
 * in to the correct AVL tree and finally the per-object lock is held.  In
 * zfs_znode_hold_exit() the process is reversed.  The per-object lock is
 * released, removed from the AVL tree and destroyed if there are no waiters.
 *
 * This scheme has two important properties:
 *
 * 1) No memory allocations are performed while holding one of the z_hold_locks.
 *    This ensures evict(), which can be called from direct memory reclaim, will
 *    never block waiting on a z_hold_locks which just happens to have hashed
 *    to the same index.
 *
 * 2) All locks used to serialize access to an object are per-object and never
 *    shared.  This minimizes lock contention without creating a large number
 *    of dedicated locks.
 *
 * On the downside it does require znode_lock_t structures to be frequently
 * allocated and freed.  However, because these are backed by a kmem cache
 * and very short lived this cost is minimal.
 */
int
zfs_znode_hold_compare(const void *a, const void *b)
{
        const znode_hold_t *zh_a = (const znode_hold_t *)a;
        const znode_hold_t *zh_b = (const znode_hold_t *)b;

        return (AVL_CMP(zh_a->zh_obj, zh_b->zh_obj));
}

boolean_t
zfs_znode_held(zfs_sb_t *zsb, uint64_t obj)
{
        znode_hold_t *zh, search;
        int i = ZFS_OBJ_HASH(zsb, obj);
        boolean_t held;

        search.zh_obj = obj;

        mutex_enter(&zsb->z_hold_locks[i]);
        zh = avl_find(&zsb->z_hold_trees[i], &search, NULL);
        held = (zh && MUTEX_HELD(&zh->zh_lock)) ? B_TRUE : B_FALSE;
        mutex_exit(&zsb->z_hold_locks[i]);

        return (held);
}

static znode_hold_t *
zfs_znode_hold_enter(zfs_sb_t *zsb, uint64_t obj)
{
        znode_hold_t *zh, *zh_new, search;
        int i = ZFS_OBJ_HASH(zsb, obj);
        boolean_t found = B_FALSE;

        zh_new = kmem_cache_alloc(znode_hold_cache, KM_SLEEP);
        zh_new->zh_obj = obj;
        search.zh_obj = obj;

        mutex_enter(&zsb->z_hold_locks[i]);
        zh = avl_find(&zsb->z_hold_trees[i], &search, NULL);
        if (likely(zh == NULL)) {
                zh = zh_new;
                avl_add(&zsb->z_hold_trees[i], zh);
        } else {
                ASSERT3U(zh->zh_obj, ==, obj);
                found = B_TRUE;
        }
        refcount_add(&zh->zh_refcount, NULL);
        mutex_exit(&zsb->z_hold_locks[i]);

        if (found == B_TRUE)
                kmem_cache_free(znode_hold_cache, zh_new);

        ASSERT(MUTEX_NOT_HELD(&zh->zh_lock));
        ASSERT3S(refcount_count(&zh->zh_refcount), >, 0);
        mutex_enter(&zh->zh_lock);

        return (zh);
}

static void
zfs_znode_hold_exit(zfs_sb_t *zsb, znode_hold_t *zh)
{
        int i = ZFS_OBJ_HASH(zsb, zh->zh_obj);
        boolean_t remove = B_FALSE;

        ASSERT(zfs_znode_held(zsb, zh->zh_obj));
        ASSERT3S(refcount_count(&zh->zh_refcount), >, 0);
        mutex_exit(&zh->zh_lock);

        mutex_enter(&zsb->z_hold_locks[i]);
        if (refcount_remove(&zh->zh_refcount, NULL) == 0) {
                avl_remove(&zsb->z_hold_trees[i], zh);
                remove = B_TRUE;
        }
        mutex_exit(&zsb->z_hold_locks[i]);

        if (remove == B_TRUE)
                kmem_cache_free(znode_hold_cache, zh);
}

int
zfs_create_share_dir(zfs_sb_t *zsb, dmu_tx_t *tx)
{
#ifdef HAVE_SMB_SHARE
        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_mode = S_IFDIR | 0555;
        vattr.va_uid = crgetuid(kcred);
        vattr.va_gid = crgetgid(kcred);

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

        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, &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;
        sa_handle_destroy(sharezp->z_sa_hdl);
        kmem_cache_free(znode_cache, sharezp);

        return (error);
#else
        return (0);
#endif /* HAVE_SMB_SHARE */
}

static void
zfs_znode_sa_init(zfs_sb_t *zsb, znode_t *zp,
    dmu_buf_t *db, dmu_object_type_t obj_type, sa_handle_t *sa_hdl)
{
        ASSERT(zfs_znode_held(zsb, zp->z_id));

        mutex_enter(&zp->z_lock);

        ASSERT(zp->z_sa_hdl == NULL);
        ASSERT(zp->z_acl_cached == NULL);
        if (sa_hdl == NULL) {
                VERIFY(0 == sa_handle_get_from_db(zsb->z_os, db, zp,
                    SA_HDL_SHARED, &zp->z_sa_hdl));
        } else {
                zp->z_sa_hdl = sa_hdl;
                sa_set_userp(sa_hdl, zp);
        }

        zp->z_is_sa = (obj_type == DMU_OT_SA) ? B_TRUE : B_FALSE;

        mutex_exit(&zp->z_lock);
}

void
zfs_znode_dmu_fini(znode_t *zp)
{
        ASSERT(zfs_znode_held(ZTOZSB(zp), zp->z_id) || zp->z_unlinked ||
            RW_WRITE_HELD(&ZTOZSB(zp)->z_teardown_inactive_lock));

        sa_handle_destroy(zp->z_sa_hdl);
        zp->z_sa_hdl = NULL;
}

/*
 * Called by new_inode() to allocate a new inode.
 */
int
zfs_inode_alloc(struct super_block *sb, struct inode **ip)
{
        znode_t *zp;

        zp = kmem_cache_alloc(znode_cache, KM_SLEEP);
        *ip = ZTOI(zp);

        return (0);
}

/*
 * Called in multiple places when an inode should be destroyed.
 */
void
zfs_inode_destroy(struct inode *ip)
{
        znode_t *zp = ITOZ(ip);
        zfs_sb_t *zsb = ZTOZSB(zp);

        mutex_enter(&zsb->z_znodes_lock);
        if (list_link_active(&zp->z_link_node)) {
                list_remove(&zsb->z_all_znodes, zp);
                zsb->z_nr_znodes--;
        }
        mutex_exit(&zsb->z_znodes_lock);

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

        if (zp->z_xattr_cached) {
                nvlist_free(zp->z_xattr_cached);
                zp->z_xattr_cached = NULL;
        }

        kmem_cache_free(znode_cache, zp);
}

static void
zfs_inode_set_ops(zfs_sb_t *zsb, struct inode *ip)
{
        uint64_t rdev = 0;

        switch (ip->i_mode & S_IFMT) {
        case S_IFREG:
                ip->i_op = &zpl_inode_operations;
                ip->i_fop = &zpl_file_operations;
                ip->i_mapping->a_ops = &zpl_address_space_operations;
                break;

        case S_IFDIR:
                ip->i_op = &zpl_dir_inode_operations;
                ip->i_fop = &zpl_dir_file_operations;
                ITOZ(ip)->z_zn_prefetch = B_TRUE;
                break;

        case S_IFLNK:
                ip->i_op = &zpl_symlink_inode_operations;
                break;

        /*
         * rdev is only stored in a SA only for device files.
         */
        case S_IFCHR:
        case S_IFBLK:
                (void) sa_lookup(ITOZ(ip)->z_sa_hdl, SA_ZPL_RDEV(zsb), &rdev,
                    sizeof (rdev));
                /*FALLTHROUGH*/
        case S_IFIFO:
        case S_IFSOCK:
                init_special_inode(ip, ip->i_mode, rdev);
                ip->i_op = &zpl_special_inode_operations;
                break;

        default:
                zfs_panic_recover("inode %llu has invalid mode: 0x%x\n",
                    (u_longlong_t)ip->i_ino, ip->i_mode);

                /* Assume the inode is a file and attempt to continue */
                ip->i_mode = S_IFREG | 0644;
                ip->i_op = &zpl_inode_operations;
                ip->i_fop = &zpl_file_operations;
                ip->i_mapping->a_ops = &zpl_address_space_operations;
                break;
        }
}

/*
 * Update the embedded inode given the znode.  We should work toward
 * eliminating this function as soon as possible by removing values
 * which are duplicated between the znode and inode.  If the generic
 * inode has the correct field it should be used, and the ZFS code
 * updated to access the inode.  This can be done incrementally.
 */
void
zfs_inode_update(znode_t *zp)
{
        zfs_sb_t        *zsb;
        struct inode    *ip;
        uint32_t        blksize;
        u_longlong_t    i_blocks;

        ASSERT(zp != NULL);
        zsb = ZTOZSB(zp);
        ip = ZTOI(zp);

        /* Skip .zfs control nodes which do not exist on disk. */
        if (zfsctl_is_node(ip))
                return;

        dmu_object_size_from_db(sa_get_db(zp->z_sa_hdl), &blksize, &i_blocks);

        spin_lock(&ip->i_lock);
        ip->i_blocks = i_blocks;
        i_size_write(ip, zp->z_size);
        spin_unlock(&ip->i_lock);
}


/*
 * Construct a znode+inode and initialize.
 *
 * 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(zfs_sb_t *zsb, dmu_buf_t *db, int blksz,
    dmu_object_type_t obj_type, uint64_t obj, sa_handle_t *hdl)
{
        znode_t *zp;
        struct inode *ip;
        uint64_t mode;
        uint64_t parent;
        uint64_t tmp_gen;
        uint64_t links;
        uint64_t z_uid, z_gid;
        uint64_t atime[2], mtime[2], ctime[2];
        sa_bulk_attr_t bulk[11];
        int count = 0;

        ASSERT(zsb != NULL);

        ip = new_inode(zsb->z_sb);
        if (ip == NULL)
                return (NULL);

        zp = ITOZ(ip);
        ASSERT(zp->z_dirlocks == NULL);
        ASSERT3P(zp->z_acl_cached, ==, NULL);
        ASSERT3P(zp->z_xattr_cached, ==, NULL);
        zp->z_moved = 0;
        zp->z_sa_hdl = NULL;
        zp->z_unlinked = 0;
        zp->z_atime_dirty = 0;
        zp->z_mapcnt = 0;
        zp->z_id = db->db_object;
        zp->z_blksz = blksz;
        zp->z_seq = 0x7A4653;
        zp->z_sync_cnt = 0;
        zp->z_is_mapped = B_FALSE;
        zp->z_is_ctldir = B_FALSE;
        zp->z_is_stale = B_FALSE;
        zp->z_range_lock.zr_size = &zp->z_size;
        zp->z_range_lock.zr_blksz = &zp->z_blksz;
        zp->z_range_lock.zr_max_blksz = &ZTOZSB(zp)->z_max_blksz;

        zfs_znode_sa_init(zsb, zp, db, obj_type, hdl);

        SA_ADD_BULK_ATTR(bulk, count, SA_ZPL_MODE(zsb), NULL, &mode, 8);
        SA_ADD_BULK_ATTR(bulk, count, SA_ZPL_GEN(zsb), NULL, &tmp_gen, 8);
        SA_ADD_BULK_ATTR(bulk, count, SA_ZPL_SIZE(zsb), NULL, &zp->z_size, 8);
        SA_ADD_BULK_ATTR(bulk, count, SA_ZPL_LINKS(zsb), NULL, &links, 8);
        SA_ADD_BULK_ATTR(bulk, count, SA_ZPL_FLAGS(zsb), NULL,
            &zp->z_pflags, 8);
        SA_ADD_BULK_ATTR(bulk, count, SA_ZPL_PARENT(zsb), NULL,
            &parent, 8);
        SA_ADD_BULK_ATTR(bulk, count, SA_ZPL_UID(zsb), NULL, &z_uid, 8);
        SA_ADD_BULK_ATTR(bulk, count, SA_ZPL_GID(zsb), NULL, &z_gid, 8);
        SA_ADD_BULK_ATTR(bulk, count, SA_ZPL_ATIME(zsb), NULL, &atime, 16);
        SA_ADD_BULK_ATTR(bulk, count, SA_ZPL_MTIME(zsb), NULL, &mtime, 16);
        SA_ADD_BULK_ATTR(bulk, count, SA_ZPL_CTIME(zsb), NULL, &ctime, 16);

        if (sa_bulk_lookup(zp->z_sa_hdl, bulk, count) != 0 ||
                tmp_gen == 0) {

                if (hdl == NULL)
                        sa_handle_destroy(zp->z_sa_hdl);
                zp->z_sa_hdl = NULL;
                goto error;
        }

        zp->z_mode = ip->i_mode = mode;
        ip->i_generation = (uint32_t)tmp_gen;
        ip->i_blkbits = SPA_MINBLOCKSHIFT;
        set_nlink(ip, (uint32_t)links);
        zfs_uid_write(ip, z_uid);
        zfs_gid_write(ip, z_gid);

        ZFS_TIME_DECODE(&ip->i_atime, atime);
        ZFS_TIME_DECODE(&ip->i_mtime, mtime);
        ZFS_TIME_DECODE(&ip->i_ctime, ctime);

        ip->i_ino = obj;
        zfs_inode_update(zp);
        zfs_inode_set_ops(zsb, ip);

        /*
         * The only way insert_inode_locked() can fail is if the ip->i_ino
         * number is already hashed for this super block.  This can never
         * happen because the inode numbers map 1:1 with the object numbers.
         *
         * The one exception is rolling back a mounted file system, but in
         * this case all the active inode are unhashed during the rollback.
         */
        VERIFY3S(insert_inode_locked(ip), ==, 0);

        mutex_enter(&zsb->z_znodes_lock);
        list_insert_tail(&zsb->z_all_znodes, zp);
        zsb->z_nr_znodes++;
        membar_producer();
        mutex_exit(&zsb->z_znodes_lock);

        unlock_new_inode(ip);
        return (zp);

error:
        iput(ip);
        return (NULL);
}

/*
 * Safely mark an inode dirty.  Inodes which are part of a read-only
 * file system or snapshot may not be dirtied.
 */
void
zfs_mark_inode_dirty(struct inode *ip)
{
        zfs_sb_t *zsb = ITOZSB(ip);

        if (zfs_is_readonly(zsb) || dmu_objset_is_snapshot(zsb->z_os))
                return;

        mark_inode_dirty(ip);
}

static uint64_t empty_xattr;
static uint64_t pad[4];
static zfs_acl_phys_t acl_phys;
/*
 * 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
 *              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, zfs_acl_ids_t *acl_ids)
{
        uint64_t        crtime[2], atime[2], mtime[2], ctime[2];
        uint64_t        mode, size, links, parent, pflags;
        uint64_t        dzp_pflags = 0;
        uint64_t        rdev = 0;
        zfs_sb_t        *zsb = ZTOZSB(dzp);
        dmu_buf_t       *db;
        timestruc_t     now;
        uint64_t        gen, obj;
        int             bonuslen;
        int             dnodesize;
        sa_handle_t     *sa_hdl;
        dmu_object_type_t obj_type;
        sa_bulk_attr_t  *sa_attrs;
        int             cnt = 0;
        zfs_acl_locator_cb_t locate = { 0 };
        znode_hold_t    *zh;

        if (zsb->z_replay) {
                obj = vap->va_nodeid;
                now = vap->va_ctime;            /* see zfs_replay_create() */
                gen = vap->va_nblocks;          /* ditto */
                dnodesize = vap->va_fsid;       /* ditto */
        } else {
                obj = 0;
                gethrestime(&now);
                gen = dmu_tx_get_txg(tx);
                dnodesize = dmu_objset_dnodesize(zsb->z_os);
        }

        if (dnodesize == 0)
                dnodesize = DNODE_MIN_SIZE;

        obj_type = zsb->z_use_sa ? DMU_OT_SA : DMU_OT_ZNODE;

        bonuslen = (obj_type == DMU_OT_SA) ?
            DN_BONUS_SIZE(dnodesize) : ZFS_OLD_ZNODE_PHYS_SIZE;

        /*
         * Create a new DMU object.
         */
        /*
         * There's currently no mechanism for pre-reading the blocks that will
         * be needed to 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 (S_ISDIR(vap->va_mode)) {
                if (zsb->z_replay) {
                        VERIFY0(zap_create_claim_norm_dnsize(zsb->z_os, obj,
                            zsb->z_norm, DMU_OT_DIRECTORY_CONTENTS,
                            obj_type, bonuslen, dnodesize, tx));
                } else {
                        obj = zap_create_norm_dnsize(zsb->z_os,
                            zsb->z_norm, DMU_OT_DIRECTORY_CONTENTS,
                            obj_type, bonuslen, dnodesize, tx);
                }
        } else {
                if (zsb->z_replay) {
                        VERIFY0(dmu_object_claim_dnsize(zsb->z_os, obj,
                            DMU_OT_PLAIN_FILE_CONTENTS, 0,
                            obj_type, bonuslen, dnodesize, tx));
                } else {
                        obj = dmu_object_alloc_dnsize(zsb->z_os,
                            DMU_OT_PLAIN_FILE_CONTENTS, 0,
                            obj_type, bonuslen, dnodesize, tx);
                }
        }

        zh = zfs_znode_hold_enter(zsb, obj);
        VERIFY(0 == sa_buf_hold(zsb->z_os, obj, NULL, &db));

        /*
         * 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_id = obj;
        } else {
                dzp_pflags = dzp->z_pflags;
        }

        /*
         * If parent is an xattr, so am I.
         */
        if (dzp_pflags & ZFS_XATTR) {
                flag |= IS_XATTR;
        }

        if (zsb->z_use_fuids)
                pflags = ZFS_ARCHIVE | ZFS_AV_MODIFIED;
        else
                pflags = 0;

        if (S_ISDIR(vap->va_mode)) {
                size = 2;               /* contents ("." and "..") */
                links = 2;
        } else {
                size = 0;
                links = 1;
        }

        if (S_ISBLK(vap->va_mode) || S_ISCHR(vap->va_mode))
                rdev = vap->va_rdev;

        parent = dzp->z_id;
        mode = acl_ids->z_mode;
        if (flag & IS_XATTR)
                pflags |= ZFS_XATTR;

        /*
         * No execs denied will be deterimed when zfs_mode_compute() is called.
         */
        pflags |= acl_ids->z_aclp->z_hints &
            (ZFS_ACL_TRIVIAL|ZFS_INHERIT_ACE|ZFS_ACL_AUTO_INHERIT|
            ZFS_ACL_DEFAULTED|ZFS_ACL_PROTECTED);

        ZFS_TIME_ENCODE(&now, crtime);
        ZFS_TIME_ENCODE(&now, ctime);

        if (vap->va_mask & ATTR_ATIME) {
                ZFS_TIME_ENCODE(&vap->va_atime, atime);
        } else {
                ZFS_TIME_ENCODE(&now, atime);
        }

        if (vap->va_mask & ATTR_MTIME) {
                ZFS_TIME_ENCODE(&vap->va_mtime, mtime);
        } else {
                ZFS_TIME_ENCODE(&now, mtime);
        }

        /* Now add in all of the "SA" attributes */
        VERIFY(0 == sa_handle_get_from_db(zsb->z_os, db, NULL, SA_HDL_SHARED,
            &sa_hdl));

        /*
         * Setup the array of attributes to be replaced/set on the new file
         *
         * order for  DMU_OT_ZNODE is critical since it needs to be constructed
         * in the old znode_phys_t format.  Don't change this ordering
         */
        sa_attrs = kmem_alloc(sizeof (sa_bulk_attr_t) * ZPL_END, KM_SLEEP);

        if (obj_type == DMU_OT_ZNODE) {
                SA_ADD_BULK_ATTR(sa_attrs, cnt, SA_ZPL_ATIME(zsb),
                    NULL, &atime, 16);
                SA_ADD_BULK_ATTR(sa_attrs, cnt, SA_ZPL_MTIME(zsb),
                    NULL, &mtime, 16);
                SA_ADD_BULK_ATTR(sa_attrs, cnt, SA_ZPL_CTIME(zsb),
                    NULL, &ctime, 16);
                SA_ADD_BULK_ATTR(sa_attrs, cnt, SA_ZPL_CRTIME(zsb),
                    NULL, &crtime, 16);
                SA_ADD_BULK_ATTR(sa_attrs, cnt, SA_ZPL_GEN(zsb),
                    NULL, &gen, 8);
                SA_ADD_BULK_ATTR(sa_attrs, cnt, SA_ZPL_MODE(zsb),
                    NULL, &mode, 8);
                SA_ADD_BULK_ATTR(sa_attrs, cnt, SA_ZPL_SIZE(zsb),
                    NULL, &size, 8);
                SA_ADD_BULK_ATTR(sa_attrs, cnt, SA_ZPL_PARENT(zsb),
                    NULL, &parent, 8);
        } else {
                SA_ADD_BULK_ATTR(sa_attrs, cnt, SA_ZPL_MODE(zsb),
                    NULL, &mode, 8);
                SA_ADD_BULK_ATTR(sa_attrs, cnt, SA_ZPL_SIZE(zsb),
                    NULL, &size, 8);
                SA_ADD_BULK_ATTR(sa_attrs, cnt, SA_ZPL_GEN(zsb),
                    NULL, &gen, 8);
                SA_ADD_BULK_ATTR(sa_attrs, cnt, SA_ZPL_UID(zsb),
                    NULL, &acl_ids->z_fuid, 8);
                SA_ADD_BULK_ATTR(sa_attrs, cnt, SA_ZPL_GID(zsb),
                    NULL, &acl_ids->z_fgid, 8);
                SA_ADD_BULK_ATTR(sa_attrs, cnt, SA_ZPL_PARENT(zsb),
                    NULL, &parent, 8);
                SA_ADD_BULK_ATTR(sa_attrs, cnt, SA_ZPL_FLAGS(zsb),
                    NULL, &pflags, 8);
                SA_ADD_BULK_ATTR(sa_attrs, cnt, SA_ZPL_ATIME(zsb),
                    NULL, &atime, 16);
                SA_ADD_BULK_ATTR(sa_attrs, cnt, SA_ZPL_MTIME(zsb),
                    NULL, &mtime, 16);
                SA_ADD_BULK_ATTR(sa_attrs, cnt, SA_ZPL_CTIME(zsb),
                    NULL, &ctime, 16);
                SA_ADD_BULK_ATTR(sa_attrs, cnt, SA_ZPL_CRTIME(zsb),
                    NULL, &crtime, 16);
        }

        SA_ADD_BULK_ATTR(sa_attrs, cnt, SA_ZPL_LINKS(zsb), NULL, &links, 8);

        if (obj_type == DMU_OT_ZNODE) {
                SA_ADD_BULK_ATTR(sa_attrs, cnt, SA_ZPL_XATTR(zsb), NULL,
                    &empty_xattr, 8);
        }
        if (obj_type == DMU_OT_ZNODE ||
            (S_ISBLK(vap->va_mode) || S_ISCHR(vap->va_mode))) {
                SA_ADD_BULK_ATTR(sa_attrs, cnt, SA_ZPL_RDEV(zsb),
                    NULL, &rdev, 8);
        }
        if (obj_type == DMU_OT_ZNODE) {
                SA_ADD_BULK_ATTR(sa_attrs, cnt, SA_ZPL_FLAGS(zsb),
                    NULL, &pflags, 8);
                SA_ADD_BULK_ATTR(sa_attrs, cnt, SA_ZPL_UID(zsb), NULL,
                    &acl_ids->z_fuid, 8);
                SA_ADD_BULK_ATTR(sa_attrs, cnt, SA_ZPL_GID(zsb), NULL,
                    &acl_ids->z_fgid, 8);
                SA_ADD_BULK_ATTR(sa_attrs, cnt, SA_ZPL_PAD(zsb), NULL, pad,
                    sizeof (uint64_t) * 4);
                SA_ADD_BULK_ATTR(sa_attrs, cnt, SA_ZPL_ZNODE_ACL(zsb), NULL,
                    &acl_phys, sizeof (zfs_acl_phys_t));
        } else if (acl_ids->z_aclp->z_version >= ZFS_ACL_VERSION_FUID) {
                SA_ADD_BULK_ATTR(sa_attrs, cnt, SA_ZPL_DACL_COUNT(zsb), NULL,
                    &acl_ids->z_aclp->z_acl_count, 8);
                locate.cb_aclp = acl_ids->z_aclp;
                SA_ADD_BULK_ATTR(sa_attrs, cnt, SA_ZPL_DACL_ACES(zsb),
                    zfs_acl_data_locator, &locate,
                    acl_ids->z_aclp->z_acl_bytes);
                mode = zfs_mode_compute(mode, acl_ids->z_aclp, &pflags,
                    acl_ids->z_fuid, acl_ids->z_fgid);
        }

        VERIFY(sa_replace_all_by_template(sa_hdl, sa_attrs, cnt, tx) == 0);

        if (!(flag & IS_ROOT_NODE)) {
                *zpp = zfs_znode_alloc(zsb, db, 0, obj_type, obj, sa_hdl);
                VERIFY(*zpp != NULL);
                VERIFY(dzp != NULL);
        } else {
                /*
                 * If we are creating the root node, the "parent" we
                 * passed in is the znode for the root.
                 */
                *zpp = dzp;

                (*zpp)->z_sa_hdl = sa_hdl;
        }

        (*zpp)->z_pflags = pflags;
        (*zpp)->z_mode = ZTOI(*zpp)->i_mode = mode;
        (*zpp)->z_dnodesize = dnodesize;

        if (obj_type == DMU_OT_ZNODE ||
            acl_ids->z_aclp->z_version < ZFS_ACL_VERSION_FUID) {
                VERIFY0(zfs_aclset_common(*zpp, acl_ids->z_aclp, cr, tx));
        }
        kmem_free(sa_attrs, sizeof (sa_bulk_attr_t) * ZPL_END);
        zfs_znode_hold_exit(zsb, zh);
}

/*
 * Update in-core attributes.  It is assumed the caller will be doing an
 * sa_bulk_update to push the changes out.
 */
void
zfs_xvattr_set(znode_t *zp, xvattr_t *xvap, dmu_tx_t *tx)
{
        xoptattr_t *xoap;

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

        if (XVA_ISSET_REQ(xvap, XAT_CREATETIME)) {
                uint64_t times[2];
                ZFS_TIME_ENCODE(&xoap->xoa_createtime, times);
                (void) sa_update(zp->z_sa_hdl, SA_ZPL_CRTIME(ZTOZSB(zp)),
                    &times, sizeof (times), tx);
                XVA_SET_RTN(xvap, XAT_CREATETIME);
        }

        if (XVA_ISSET_REQ(xvap, XAT_READONLY)) {
                ZFS_ATTR_SET(zp, ZFS_READONLY, xoap->xoa_readonly,
                    zp->z_pflags, tx);
                XVA_SET_RTN(xvap, XAT_READONLY);
        }
        if (XVA_ISSET_REQ(xvap, XAT_HIDDEN)) {
                ZFS_ATTR_SET(zp, ZFS_HIDDEN, xoap->xoa_hidden,
                    zp->z_pflags, tx);
                XVA_SET_RTN(xvap, XAT_HIDDEN);
        }
        if (XVA_ISSET_REQ(xvap, XAT_SYSTEM)) {
                ZFS_ATTR_SET(zp, ZFS_SYSTEM, xoap->xoa_system,
                    zp->z_pflags, tx);
                XVA_SET_RTN(xvap, XAT_SYSTEM);
        }
        if (XVA_ISSET_REQ(xvap, XAT_ARCHIVE)) {
                ZFS_ATTR_SET(zp, ZFS_ARCHIVE, xoap->xoa_archive,
                    zp->z_pflags, tx);
                XVA_SET_RTN(xvap, XAT_ARCHIVE);
        }
        if (XVA_ISSET_REQ(xvap, XAT_IMMUTABLE)) {
                ZFS_ATTR_SET(zp, ZFS_IMMUTABLE, xoap->xoa_immutable,
                    zp->z_pflags, tx);
                XVA_SET_RTN(xvap, XAT_IMMUTABLE);

                ZTOI(zp)->i_flags |= S_IMMUTABLE;
        } else {
                ZTOI(zp)->i_flags &= ~S_IMMUTABLE;
        }

        if (XVA_ISSET_REQ(xvap, XAT_NOUNLINK)) {
                ZFS_ATTR_SET(zp, ZFS_NOUNLINK, xoap->xoa_nounlink,
                    zp->z_pflags, tx);
                XVA_SET_RTN(xvap, XAT_NOUNLINK);
        }
        if (XVA_ISSET_REQ(xvap, XAT_APPENDONLY)) {
                ZFS_ATTR_SET(zp, ZFS_APPENDONLY, xoap->xoa_appendonly,
                    zp->z_pflags, tx);
                XVA_SET_RTN(xvap, XAT_APPENDONLY);

                ZTOI(zp)->i_flags |= S_APPEND;
        } else {

                ZTOI(zp)->i_flags &= ~S_APPEND;
        }

        if (XVA_ISSET_REQ(xvap, XAT_NODUMP)) {
                ZFS_ATTR_SET(zp, ZFS_NODUMP, xoap->xoa_nodump,
                    zp->z_pflags, tx);
                XVA_SET_RTN(xvap, XAT_NODUMP);
        }
        if (XVA_ISSET_REQ(xvap, XAT_OPAQUE)) {
                ZFS_ATTR_SET(zp, ZFS_OPAQUE, xoap->xoa_opaque,
                    zp->z_pflags, tx);
                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, zp->z_pflags, tx);
                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,
                    zp->z_pflags, tx);
                XVA_SET_RTN(xvap, XAT_AV_MODIFIED);
        }
        if (XVA_ISSET_REQ(xvap, XAT_AV_SCANSTAMP)) {
                zfs_sa_set_scanstamp(zp, xvap, tx);
                XVA_SET_RTN(xvap, XAT_AV_SCANSTAMP);
        }
        if (XVA_ISSET_REQ(xvap, XAT_REPARSE)) {
                ZFS_ATTR_SET(zp, ZFS_REPARSE, xoap->xoa_reparse,
                    zp->z_pflags, tx);
                XVA_SET_RTN(xvap, XAT_REPARSE);
        }
        if (XVA_ISSET_REQ(xvap, XAT_OFFLINE)) {
                ZFS_ATTR_SET(zp, ZFS_OFFLINE, xoap->xoa_offline,
                    zp->z_pflags, tx);
                XVA_SET_RTN(xvap, XAT_OFFLINE);
        }
        if (XVA_ISSET_REQ(xvap, XAT_SPARSE)) {
                ZFS_ATTR_SET(zp, ZFS_SPARSE, xoap->xoa_sparse,
                    zp->z_pflags, tx);
                XVA_SET_RTN(xvap, XAT_SPARSE);
        }
}

int
zfs_zget(zfs_sb_t *zsb, uint64_t obj_num, znode_t **zpp)
{
        dmu_object_info_t doi;
        dmu_buf_t       *db;
        znode_t         *zp;
        znode_hold_t    *zh;
        int err;
        sa_handle_t     *hdl;

        *zpp = NULL;

again:
        zh = zfs_znode_hold_enter(zsb, obj_num);

        err = sa_buf_hold(zsb->z_os, obj_num, NULL, &db);
        if (err) {
                zfs_znode_hold_exit(zsb, zh);
                return (err);
        }

        dmu_object_info_from_db(db, &doi);
        if (doi.doi_bonus_type != DMU_OT_SA &&
            (doi.doi_bonus_type != DMU_OT_ZNODE ||
            (doi.doi_bonus_type == DMU_OT_ZNODE &&
            doi.doi_bonus_size < sizeof (znode_phys_t)))) {
                sa_buf_rele(db, NULL);
                zfs_znode_hold_exit(zsb, zh);
                return (SET_ERROR(EINVAL));
        }

        hdl = dmu_buf_get_user(db);
        if (hdl != NULL) {
                zp = sa_get_userdata(hdl);


                /*
                 * Since "SA" does immediate eviction we
                 * should never find a sa handle that doesn't
                 * know about the znode.
                 */

                ASSERT3P(zp, !=, NULL);

                mutex_enter(&zp->z_lock);
                ASSERT3U(zp->z_id, ==, obj_num);
                if (zp->z_unlinked) {
                        err = SET_ERROR(ENOENT);
                } else {
                        /*
                         * If igrab() returns NULL the VFS has independently
                         * determined the inode should be evicted and has
                         * called iput_final() to start the eviction process.
                         * The SA handle is still valid but because the VFS
                         * requires that the eviction succeed we must drop
                         * our locks and references to allow the eviction to
                         * complete.  The zfs_zget() may then be retried.
                         *
                         * This unlikely case could be optimized by registering
                         * a sops->drop_inode() callback.  The callback would
                         * need to detect the active SA hold thereby informing
                         * the VFS that this inode should not be evicted.
                         */
                        if (igrab(ZTOI(zp)) == NULL) {
                                mutex_exit(&zp->z_lock);
                                sa_buf_rele(db, NULL);
                                zfs_znode_hold_exit(zsb, zh);
                                /* inode might need this to finish evict */
                                cond_resched();
                                goto again;
                        }
                        *zpp = zp;
                        err = 0;
                }
                mutex_exit(&zp->z_lock);
                sa_buf_rele(db, NULL);
                zfs_znode_hold_exit(zsb, zh);
                return (err);
        }

        /*
         * Not found create new znode/vnode but only if file exists.
         *
         * There is a small window where zfs_vget() could
         * find this object while a file create is still in
         * progress.  This is checked for in zfs_znode_alloc()
         *
         * if zfs_znode_alloc() fails it will drop the hold on the
         * bonus buffer.
         */
        zp = zfs_znode_alloc(zsb, db, doi.doi_data_block_size,
            doi.doi_bonus_type, obj_num, NULL);
        if (zp == NULL) {
                err = SET_ERROR(ENOENT);
        } else {
                *zpp = zp;
        }
        zfs_znode_hold_exit(zsb, zh);
        return (err);
}

int
zfs_rezget(znode_t *zp)
{
        zfs_sb_t *zsb = ZTOZSB(zp);
        dmu_object_info_t doi;
        dmu_buf_t *db;
        uint64_t obj_num = zp->z_id;
        uint64_t mode;
        uint64_t links;
        sa_bulk_attr_t bulk[10];
        int err;
        int count = 0;
        uint64_t gen;
        uint64_t z_uid, z_gid;
        uint64_t atime[2], mtime[2], ctime[2];
        znode_hold_t *zh;

        /*
         * skip ctldir, otherwise they will always get invalidated. This will
         * cause funny behaviour for the mounted snapdirs. Especially for
         * Linux >= 3.18, d_invalidate will detach the mountpoint and prevent
         * anyone automount it again as long as someone is still using the
         * detached mount.
         */
        if (zp->z_is_ctldir)
                return (0);

        zh = zfs_znode_hold_enter(zsb, obj_num);

        mutex_enter(&zp->z_acl_lock);
        if (zp->z_acl_cached) {
                zfs_acl_free(zp->z_acl_cached);
                zp->z_acl_cached = NULL;
        }
        mutex_exit(&zp->z_acl_lock);

        rw_enter(&zp->z_xattr_lock, RW_WRITER);
        if (zp->z_xattr_cached) {
                nvlist_free(zp->z_xattr_cached);
                zp->z_xattr_cached = NULL;
        }
        rw_exit(&zp->z_xattr_lock);

        ASSERT(zp->z_sa_hdl == NULL);
        err = sa_buf_hold(zsb->z_os, obj_num, NULL, &db);
        if (err) {
                zfs_znode_hold_exit(zsb, zh);
                return (err);
        }

        dmu_object_info_from_db(db, &doi);
        if (doi.doi_bonus_type != DMU_OT_SA &&
            (doi.doi_bonus_type != DMU_OT_ZNODE ||
            (doi.doi_bonus_type == DMU_OT_ZNODE &&
            doi.doi_bonus_size < sizeof (znode_phys_t)))) {
                sa_buf_rele(db, NULL);
                zfs_znode_hold_exit(zsb, zh);
                return (SET_ERROR(EINVAL));
        }

        zfs_znode_sa_init(zsb, zp, db, doi.doi_bonus_type, NULL);

        /* reload cached values */
        SA_ADD_BULK_ATTR(bulk, count, SA_ZPL_GEN(zsb), NULL,
            &gen, sizeof (gen));
        SA_ADD_BULK_ATTR(bulk, count, SA_ZPL_SIZE(zsb), NULL,
            &zp->z_size, sizeof (zp->z_size));
        SA_ADD_BULK_ATTR(bulk, count, SA_ZPL_LINKS(zsb), NULL,
            &links, sizeof (links));
        SA_ADD_BULK_ATTR(bulk, count, SA_ZPL_FLAGS(zsb), NULL,
            &zp->z_pflags, sizeof (zp->z_pflags));
        SA_ADD_BULK_ATTR(bulk, count, SA_ZPL_UID(zsb), NULL,
            &z_uid, sizeof (z_uid));
        SA_ADD_BULK_ATTR(bulk, count, SA_ZPL_GID(zsb), NULL,
            &z_gid, sizeof (z_gid));
        SA_ADD_BULK_ATTR(bulk, count, SA_ZPL_MODE(zsb), NULL,
            &mode, sizeof (mode));
        SA_ADD_BULK_ATTR(bulk, count, SA_ZPL_ATIME(zsb), NULL,
            &atime, 16);
        SA_ADD_BULK_ATTR(bulk, count, SA_ZPL_MTIME(zsb), NULL,
            &mtime, 16);
        SA_ADD_BULK_ATTR(bulk, count, SA_ZPL_CTIME(zsb), NULL,
            &ctime, 16);

        if (sa_bulk_lookup(zp->z_sa_hdl, bulk, count)) {
                zfs_znode_dmu_fini(zp);
                zfs_znode_hold_exit(zsb, zh);
                return (SET_ERROR(EIO));
        }

        zp->z_mode = ZTOI(zp)->i_mode = mode;
        zfs_uid_write(ZTOI(zp), z_uid);
        zfs_gid_write(ZTOI(zp), z_gid);

        ZFS_TIME_DECODE(&ZTOI(zp)->i_atime, atime);
        ZFS_TIME_DECODE(&ZTOI(zp)->i_mtime, mtime);
        ZFS_TIME_DECODE(&ZTOI(zp)->i_ctime, ctime);

        if (gen != ZTOI(zp)->i_generation) {
                zfs_znode_dmu_fini(zp);
                zfs_znode_hold_exit(zsb, zh);
                return (SET_ERROR(EIO));
        }

        zp->z_unlinked = (ZTOI(zp)->i_nlink == 0);
        set_nlink(ZTOI(zp), (uint32_t)links);

        zp->z_blksz = doi.doi_data_block_size;
        zp->z_atime_dirty = 0;
        zfs_inode_update(zp);


        zfs_znode_hold_exit(zsb, zh);

        return (0);
}

void
zfs_znode_delete(znode_t *zp, dmu_tx_t *tx)
{
        zfs_sb_t *zsb = ZTOZSB(zp);
        objset_t *os = zsb->z_os;
        uint64_t obj = zp->z_id;
        uint64_t acl_obj = zfs_external_acl(zp);
        znode_hold_t *zh;

        zh = zfs_znode_hold_enter(zsb, obj);
        if (acl_obj) {
                VERIFY(!zp->z_is_sa);
                VERIFY(0 == dmu_object_free(os, acl_obj, tx));
        }
        VERIFY(0 == dmu_object_free(os, obj, tx));
        zfs_znode_dmu_fini(zp);
        zfs_znode_hold_exit(zsb, zh);
}

void
zfs_zinactive(znode_t *zp)
{
        zfs_sb_t *zsb = ZTOZSB(zp);
        uint64_t z_id = zp->z_id;
        znode_hold_t *zh;

        ASSERT(zp->z_sa_hdl);

        /*
         * Don't allow a zfs_zget() while were trying to release this znode.
         */
        zh = zfs_znode_hold_enter(zsb, z_id);

        mutex_enter(&zp->z_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_znode_hold_exit(zsb, zh);
                zfs_rmnode(zp);
                return;
        }

        mutex_exit(&zp->z_lock);
        zfs_znode_dmu_fini(zp);

        zfs_znode_hold_exit(zsb, zh);
}

static inline int
zfs_compare_timespec(struct timespec *t1, struct timespec *t2)
{
        if (t1->tv_sec < t2->tv_sec)
                return (-1);

        if (t1->tv_sec > t2->tv_sec)
                return (1);

        return (t1->tv_nsec - t2->tv_nsec);
}

/*
 * Prepare to update znode time stamps.
 *
 *      IN:     zp      - znode requiring timestamp update
 *              flag    - ATTR_MTIME, ATTR_CTIME flags
 *
 *      OUT:    zp      - z_seq
 *              mtime   - new mtime
 *              ctime   - new ctime
 *
 *      Note: We don't update atime here, because we rely on Linux VFS to do
 *      atime updating.
 */
void
zfs_tstamp_update_setup(znode_t *zp, uint_t flag, uint64_t mtime[2],
    uint64_t ctime[2])
{
        timestruc_t     now;

        gethrestime(&now);

        zp->z_seq++;

        if (flag & ATTR_MTIME) {
                ZFS_TIME_ENCODE(&now, mtime);
                ZFS_TIME_DECODE(&(ZTOI(zp)->i_mtime), mtime);
                if (ZTOZSB(zp)->z_use_fuids) {
                        zp->z_pflags |= (ZFS_ARCHIVE |
                            ZFS_AV_MODIFIED);
                }
        }

        if (flag & ATTR_CTIME) {
                ZFS_TIME_ENCODE(&now, ctime);
                ZFS_TIME_DECODE(&(ZTOI(zp)->i_ctime), ctime);
                if (ZTOZSB(zp)->z_use_fuids)
                        zp->z_pflags |= ZFS_ARCHIVE;
        }
}

/*
 * 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_size > zp->z_blksz)
                return;

        error = dmu_object_set_blocksize(ZTOZSB(zp)->z_os, zp->z_id,
            size, 0, tx);

        if (error == ENOTSUP)
                return;
        ASSERT0(error);

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

/*
 * Increase the file length
 *
 *      IN:     zp      - znode of file to free data in.
 *              end     - new end-of-file
 *
 *      RETURN: 0 on success, error code on failure
 */
static int
zfs_extend(znode_t *zp, uint64_t end)
{
        zfs_sb_t *zsb = ZTOZSB(zp);
        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->z_range_lock, 0, UINT64_MAX, RL_WRITER);

        /*
         * Nothing to do if file already at desired length.
         */
        if (end <= zp->z_size) {
                zfs_range_unlock(rl);
                return (0);
        }
        tx = dmu_tx_create(zsb->z_os);
        dmu_tx_hold_sa(tx, zp->z_sa_hdl, B_FALSE);
        zfs_sa_upgrade_txholds(tx, zp);
        if (end > zp->z_blksz &&
            (!ISP2(zp->z_blksz) || zp->z_blksz < zsb->z_max_blksz)) {
                /*
                 * We are growing the file past the current block size.
                 */
                if (zp->z_blksz > ZTOZSB(zp)->z_max_blksz) {
                        /*
                         * File's blocksize is already larger than the
                         * "recordsize" property.  Only let it grow to
                         * the next power of 2.
                         */
                        ASSERT(!ISP2(zp->z_blksz));
                        newblksz = MIN(end, 1 << highbit64(zp->z_blksz));
                } else {
                        newblksz = MIN(end, ZTOZSB(zp)->z_max_blksz);
                }
                dmu_tx_hold_write(tx, zp->z_id, 0, newblksz);
        } else {
                newblksz = 0;
        }

        error = dmu_tx_assign(tx, TXG_WAIT);
        if (error) {
                dmu_tx_abort(tx);
                zfs_range_unlock(rl);
                return (error);
        }

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

        zp->z_size = end;

        VERIFY(0 == sa_update(zp->z_sa_hdl, SA_ZPL_SIZE(ZTOZSB(zp)),
            &zp->z_size, sizeof (zp->z_size), tx));

        zfs_range_unlock(rl);

        dmu_tx_commit(tx);

        return (0);
}

/*
 * zfs_zero_partial_page - Modeled after update_pages() but
 * with different arguments and semantics for use by zfs_freesp().
 *
 * Zeroes a piece of a single page cache entry for zp at offset
 * start and length len.
 *
 * Caller must acquire a range lock on the file for the region
 * being zeroed in order that the ARC and page cache stay in sync.
 */
static void
zfs_zero_partial_page(znode_t *zp, uint64_t start, uint64_t len)
{
        struct address_space *mp = ZTOI(zp)->i_mapping;
        struct page *pp;
        int64_t off;
        void *pb;

        ASSERT((start & PAGE_MASK) == ((start + len - 1) & PAGE_MASK));

        off = start & (PAGE_SIZE - 1);
        start &= PAGE_MASK;

        pp = find_lock_page(mp, start >> PAGE_SHIFT);
        if (pp) {
                if (mapping_writably_mapped(mp))
                        flush_dcache_page(pp);

                pb = kmap(pp);
                bzero(pb + off, len);
                kunmap(pp);

                if (mapping_writably_mapped(mp))
                        flush_dcache_page(pp);

                mark_page_accessed(pp);
                SetPageUptodate(pp);
                ClearPageError(pp);
                unlock_page(pp);
                put_page(pp);
        }
}

/*
 * 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 on success, error code on failure
 */
static int
zfs_free_range(znode_t *zp, uint64_t off, uint64_t len)
{
        zfs_sb_t *zsb = ZTOZSB(zp);
        rl_t *rl;
        int error;

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

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

        if (off + len > zp->z_size)
                len = zp->z_size - off;

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

        /*
         * Zero partial page cache entries.  This must be done under a
         * range lock in order to keep the ARC and page cache in sync.
         */
        if (zp->z_is_mapped) {
                loff_t first_page, last_page, page_len;
                loff_t first_page_offset, last_page_offset;

                /* first possible full page in hole */
                first_page = (off + PAGE_SIZE - 1) >> PAGE_SHIFT;
                /* last page of hole */
                last_page = (off + len) >> PAGE_SHIFT;

                /* offset of first_page */
                first_page_offset = first_page << PAGE_SHIFT;
                /* offset of last_page */
                last_page_offset = last_page << PAGE_SHIFT;

                /* truncate whole pages */
                if (last_page_offset > first_page_offset) {
                        truncate_inode_pages_range(ZTOI(zp)->i_mapping,
                            first_page_offset, last_page_offset - 1);
                }

                /* truncate sub-page ranges */
                if (first_page > last_page) {
                        /* entire punched area within a single page */
                        zfs_zero_partial_page(zp, off, len);
                } else {
                        /* beginning of punched area at the end of a page */
                        page_len  = first_page_offset - off;
                        if (page_len > 0)
                                zfs_zero_partial_page(zp, off, page_len);

                        /* end of punched area at the beginning of a page */
                        page_len = off + len - last_page_offset;
                        if (page_len > 0)
                                zfs_zero_partial_page(zp, last_page_offset,
                                    page_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 on success, error code on failure
 */
static int
zfs_trunc(znode_t *zp, uint64_t end)
{
        zfs_sb_t *zsb = ZTOZSB(zp);
        dmu_tx_t *tx;
        rl_t *rl;
        int error;
        sa_bulk_attr_t bulk[2];
        int count = 0;

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

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

        error = dmu_free_long_range(zsb->z_os, zp->z_id, end,  -1);
        if (error) {
                zfs_range_unlock(rl);
                return (error);
        }
        tx = dmu_tx_create(zsb->z_os);
        dmu_tx_hold_sa(tx, zp->z_sa_hdl, B_FALSE);
        zfs_sa_upgrade_txholds(tx, zp);
        dmu_tx_mark_netfree(tx);
        error = dmu_tx_assign(tx, TXG_WAIT);
        if (error) {
                dmu_tx_abort(tx);
                zfs_range_unlock(rl);
                return (error);
        }

        zp->z_size = end;
        SA_ADD_BULK_ATTR(bulk, count, SA_ZPL_SIZE(zsb),
            NULL, &zp->z_size, sizeof (zp->z_size));

        if (end == 0) {
                zp->z_pflags &= ~ZFS_SPARSE;
                SA_ADD_BULK_ATTR(bulk, count, SA_ZPL_FLAGS(zsb),
                    NULL, &zp->z_pflags, 8);
        }
        VERIFY(sa_bulk_update(zp->z_sa_hdl, bulk, count, tx) == 0);

        dmu_tx_commit(tx);

        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 on success, error code on failure
 */
int
zfs_freesp(znode_t *zp, uint64_t off, uint64_t len, int flag, boolean_t log)
{
        dmu_tx_t *tx;
        zfs_sb_t *zsb = ZTOZSB(zp);
        zilog_t *zilog = zsb->z_log;
        uint64_t mode;
        uint64_t mtime[2], ctime[2];
        sa_bulk_attr_t bulk[3];
        int count = 0;
        int error;

        if ((error = sa_lookup(zp->z_sa_hdl, SA_ZPL_MODE(zsb), &mode,
            sizeof (mode))) != 0)
                return (error);

        if (off > zp->z_size) {
                error =  zfs_extend(zp, off+len);
                if (error == 0 && log)
                        goto log;
                goto out;
        }

        if (len == 0) {
                error = zfs_trunc(zp, off);
        } else {
                if ((error = zfs_free_range(zp, off, len)) == 0 &&
                    off + len > zp->z_size)
                        error = zfs_extend(zp, off+len);
        }
        if (error || !log)
                goto out;
log:
        tx = dmu_tx_create(zsb->z_os);
        dmu_tx_hold_sa(tx, zp->z_sa_hdl, B_FALSE);
        zfs_sa_upgrade_txholds(tx, zp);
        error = dmu_tx_assign(tx, TXG_WAIT);
        if (error) {
                dmu_tx_abort(tx);
                goto out;
        }

        SA_ADD_BULK_ATTR(bulk, count, SA_ZPL_MTIME(zsb), NULL, mtime, 16);
        SA_ADD_BULK_ATTR(bulk, count, SA_ZPL_CTIME(zsb), NULL, ctime, 16);
        SA_ADD_BULK_ATTR(bulk, count, SA_ZPL_FLAGS(zsb),
            NULL, &zp->z_pflags, 8);
        zfs_tstamp_update_setup(zp, CONTENT_MODIFIED, mtime, ctime);
        error = sa_bulk_update(zp->z_sa_hdl, bulk, count, tx);
        ASSERT(error == 0);

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

        dmu_tx_commit(tx);

        zfs_inode_update(zp);
        error = 0;

out:
        /*
         * Truncate the page cache - for file truncate operations, use
         * the purpose-built API for truncations.  For punching operations,
         * the truncation is handled under a range lock in zfs_free_range.
         */
        if (len == 0)
                truncate_setsize(ZTOI(zp), off);
        return (error);
}

void
zfs_create_fs(objset_t *os, cred_t *cr, nvlist_t *zplprops, dmu_tx_t *tx)
{
        struct super_block *sb;
        zfs_sb_t        *zsb;
        uint64_t        moid, obj, sa_obj, version;
        uint64_t        sense = ZFS_CASE_SENSITIVE;
        uint64_t        norm = 0;
        nvpair_t        *elem;
        int             size;
        int             error;
        int             i;
        znode_t         *rootzp = NULL;
        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);

        /*
         * Give dmu_object_alloc() a hint about where to start
         * allocating new objects. Otherwise, since the metadnode's
         * dnode_phys_t structure isn't initialized yet, dmu_object_next()
         * would fail and we'd have to skip to the next dnode block.
         */
        os->os_obj_next = moid + 1;

        /*
         * Set starting attributes.
         */
        version = zfs_zpl_version_map(spa_version(dmu_objset_spa(os)));
        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 zap object used for SA attribute registration
         */

        if (version >= ZPL_VERSION_SA) {
                sa_obj = zap_create(os, DMU_OT_SA_MASTER_NODE,
                    DMU_OT_NONE, 0, tx);
                error = zap_add(os, moid, ZFS_SA_ATTRS, 8, 1, &sa_obj, tx);
                ASSERT(error == 0);
        } else {
                sa_obj = 0;
        }
        /*
         * 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/inode/zsb/sb
         * to allow zfs_mknode to work.
         */
        vattr.va_mask = ATTR_MODE|ATTR_UID|ATTR_GID;
        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_moved = 0;
        rootzp->z_unlinked = 0;
        rootzp->z_atime_dirty = 0;
        rootzp->z_is_sa = USE_SA(version, os);

        zsb = kmem_zalloc(sizeof (zfs_sb_t), KM_SLEEP);
        zsb->z_os = os;
        zsb->z_parent = zsb;
        zsb->z_version = version;
        zsb->z_use_fuids = USE_FUIDS(version, os);
        zsb->z_use_sa = USE_SA(version, os);
        zsb->z_norm = norm;

        sb = kmem_zalloc(sizeof (struct super_block), KM_SLEEP);
        sb->s_fs_info = zsb;

        ZTOI(rootzp)->i_sb = sb;

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

        ASSERT(error == 0);

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

        mutex_init(&zsb->z_znodes_lock, NULL, MUTEX_DEFAULT, NULL);
        list_create(&zsb->z_all_znodes, sizeof (znode_t),
            offsetof(znode_t, z_link_node));

        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);
        }

        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, &acl_ids);
        ASSERT3P(zp, ==, rootzp);
        error = zap_add(os, moid, ZFS_ROOT_OBJ, 8, 1, &rootzp->z_id, tx);
        ASSERT(error == 0);
        zfs_acl_ids_free(&acl_ids);

        atomic_set(&ZTOI(rootzp)->i_count, 0);
        sa_handle_destroy(rootzp->z_sa_hdl);
        kmem_cache_free(znode_cache, rootzp);

        /*
         * Create shares directory
         */
        error = zfs_create_share_dir(zsb, tx);
        ASSERT(error == 0);

        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);
        kmem_free(sb, sizeof (struct super_block));
        kmem_free(zsb, sizeof (zfs_sb_t));
}
#endif /* _KERNEL */

static int
zfs_sa_setup(objset_t *osp, sa_attr_type_t **sa_table)
{
        uint64_t sa_obj = 0;
        int error;

        error = zap_lookup(osp, MASTER_NODE_OBJ, ZFS_SA_ATTRS, 8, 1, &sa_obj);
        if (error != 0 && error != ENOENT)
                return (error);

        error = sa_setup(osp, sa_obj, zfs_attr_table, ZPL_END, sa_table);
        return (error);
}

static int
zfs_grab_sa_handle(objset_t *osp, uint64_t obj, sa_handle_t **hdlp,
    dmu_buf_t **db, void *tag)
{
        dmu_object_info_t doi;
        int error;

        if ((error = sa_buf_hold(osp, obj, tag, db)) != 0)
                return (error);

        dmu_object_info_from_db(*db, &doi);
        if ((doi.doi_bonus_type != DMU_OT_SA &&
            doi.doi_bonus_type != DMU_OT_ZNODE) ||
            (doi.doi_bonus_type == DMU_OT_ZNODE &&
            doi.doi_bonus_size < sizeof (znode_phys_t))) {
                sa_buf_rele(*db, tag);
                return (SET_ERROR(ENOTSUP));
        }

        error = sa_handle_get(osp, obj, NULL, SA_HDL_PRIVATE, hdlp);
        if (error != 0) {
                sa_buf_rele(*db, tag);
                return (error);
        }

        return (0);
}

void
zfs_release_sa_handle(sa_handle_t *hdl, dmu_buf_t *db, void *tag)
{
        sa_handle_destroy(hdl);
        sa_buf_rele(db, tag);
}

/*
 * 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, sa_handle_t *hdl, sa_attr_type_t *sa_table,
    uint64_t *pobjp, int *is_xattrdir)
{
        uint64_t parent;
        uint64_t pflags;
        uint64_t mode;
        uint64_t parent_mode;
        sa_bulk_attr_t bulk[3];
        sa_handle_t *sa_hdl;
        dmu_buf_t *sa_db;
        int count = 0;
        int error;

        SA_ADD_BULK_ATTR(bulk, count, sa_table[ZPL_PARENT], NULL,
            &parent, sizeof (parent));
        SA_ADD_BULK_ATTR(bulk, count, sa_table[ZPL_FLAGS], NULL,
            &pflags, sizeof (pflags));
        SA_ADD_BULK_ATTR(bulk, count, sa_table[ZPL_MODE], NULL,
            &mode, sizeof (mode));

        if ((error = sa_bulk_lookup(hdl, bulk, count)) != 0)
                return (error);

        /*
         * When a link is removed its parent pointer is not changed and will
         * be invalid.  There are two cases where a link is removed but the
         * file stays around, when it goes to the delete queue and when there
         * are additional links.
         */
        error = zfs_grab_sa_handle(osp, parent, &sa_hdl, &sa_db, FTAG);
        if (error != 0)
                return (error);

        error = sa_lookup(sa_hdl, ZPL_MODE, &parent_mode, sizeof (parent_mode));
        zfs_release_sa_handle(sa_hdl, sa_db, FTAG);
        if (error != 0)
                return (error);

        *is_xattrdir = ((pflags & ZFS_XATTR) != 0) && S_ISDIR(mode);

        /*
         * Extended attributes can be applied to files, directories, etc.
         * Otherwise the parent must be a directory.
         */
        if (!*is_xattrdir && !S_ISDIR(parent_mode))
                return (EINVAL);

        *pobjp = parent;

        return (0);
}

/*
 * Given an object number, return some zpl level statistics
 */
static int
zfs_obj_to_stats_impl(sa_handle_t *hdl, sa_attr_type_t *sa_table,
    zfs_stat_t *sb)
{
        sa_bulk_attr_t bulk[4];
        int count = 0;

        SA_ADD_BULK_ATTR(bulk, count, sa_table[ZPL_MODE], NULL,
            &sb->zs_mode, sizeof (sb->zs_mode));
        SA_ADD_BULK_ATTR(bulk, count, sa_table[ZPL_GEN], NULL,
            &sb->zs_gen, sizeof (sb->zs_gen));
        SA_ADD_BULK_ATTR(bulk, count, sa_table[ZPL_LINKS], NULL,
            &sb->zs_links, sizeof (sb->zs_links));
        SA_ADD_BULK_ATTR(bulk, count, sa_table[ZPL_CTIME], NULL,
            &sb->zs_ctime, sizeof (sb->zs_ctime));

        return (sa_bulk_lookup(hdl, bulk, count));
}

static int
zfs_obj_to_path_impl(objset_t *osp, uint64_t obj, sa_handle_t *hdl,
    sa_attr_type_t *sa_table, char *buf, int len)
{
        sa_handle_t *sa_hdl;
        sa_handle_t *prevhdl = NULL;
        dmu_buf_t *prevdb = NULL;
        dmu_buf_t *sa_db = NULL;
        char *path = buf + len - 1;
        int error;

        *path = '\0';
        sa_hdl = hdl;

        for (;;) {
                uint64_t pobj = 0;
                char component[MAXNAMELEN + 2];
                size_t complen;
                int is_xattrdir = 0;

                if (prevdb)
                        zfs_release_sa_handle(prevhdl, prevdb, FTAG);

                if ((error = zfs_obj_to_pobj(osp, sa_hdl, sa_table, &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 (sa_hdl != hdl) {
                        prevhdl = sa_hdl;
                        prevdb = sa_db;
                }
                error = zfs_grab_sa_handle(osp, obj, &sa_hdl, &sa_db, FTAG);
                if (error != 0) {
                        sa_hdl = prevhdl;
                        sa_db = prevdb;
                        break;
                }
        }

        if (sa_hdl != NULL && sa_hdl != hdl) {
                ASSERT(sa_db != NULL);
                zfs_release_sa_handle(sa_hdl, sa_db, FTAG);
        }

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

        return (error);
}

int
zfs_obj_to_path(objset_t *osp, uint64_t obj, char *buf, int len)
{
        sa_attr_type_t *sa_table;
        sa_handle_t *hdl;
        dmu_buf_t *db;
        int error;

        error = zfs_sa_setup(osp, &sa_table);
        if (error != 0)
                return (error);

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

        error = zfs_obj_to_path_impl(osp, obj, hdl, sa_table, buf, len);

        zfs_release_sa_handle(hdl, db, FTAG);
        return (error);
}

int
zfs_obj_to_stats(objset_t *osp, uint64_t obj, zfs_stat_t *sb,
    char *buf, int len)
{
        char *path = buf + len - 1;
        sa_attr_type_t *sa_table;
        sa_handle_t *hdl;
        dmu_buf_t *db;
        int error;

        *path = '\0';

        error = zfs_sa_setup(osp, &sa_table);
        if (error != 0)
                return (error);

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

        error = zfs_obj_to_stats_impl(hdl, sa_table, sb);
        if (error != 0) {
                zfs_release_sa_handle(hdl, db, FTAG);
                return (error);
        }

        error = zfs_obj_to_path_impl(osp, obj, hdl, sa_table, buf, len);

        zfs_release_sa_handle(hdl, db, FTAG);
        return (error);
}

#if defined(_KERNEL) && defined(HAVE_SPL)
EXPORT_SYMBOL(zfs_create_fs);
EXPORT_SYMBOL(zfs_obj_to_path);

module_param(zfs_object_mutex_size, uint, 0644);
MODULE_PARM_DESC(zfs_object_mutex_size, "Size of znode hold array");
#endif