C++ dmu_tx_create函数代码示例

/*
 * Ensure the zap is flushed then inform the VFS of the capacity change.
 */
static int
zvol_update_volsize(uint64_t volsize, objset_t *os)
{
	dmu_tx_t *tx;
	int error;

	ASSERT(MUTEX_HELD(&zvol_state_lock));

	tx = dmu_tx_create(os);
	dmu_tx_hold_zap(tx, ZVOL_ZAP_OBJ, TRUE, NULL);
	error = dmu_tx_assign(tx, TXG_WAIT);
	if (error) {
		dmu_tx_abort(tx);
		return (SET_ERROR(error));
	}

	error = zap_update(os, ZVOL_ZAP_OBJ, "size", 8, 1,
	    &volsize, tx);
	dmu_tx_commit(tx);

	if (error == 0)
		error = dmu_free_long_range(os,
		    ZVOL_OBJ, volsize, DMU_OBJECT_END);

	return (error);
}

/*
 * Replay a TX_WRITE ZIL transaction that didn't get committed
 * after a system failure
 */
static int
zvol_replay_write(zvol_state_t *zv, lr_write_t *lr, boolean_t byteswap)
{
	objset_t *os = zv->zv_objset;
	char *data = (char *)(lr + 1);	/* data follows lr_write_t */
	uint64_t off = lr->lr_offset;
	uint64_t len = lr->lr_length;
	dmu_tx_t *tx;
	int error;

	if (byteswap)
		byteswap_uint64_array(lr, sizeof (*lr));

	tx = dmu_tx_create(os);
	dmu_tx_hold_write(tx, ZVOL_OBJ, off, len);
	error = dmu_tx_assign(tx, TXG_WAIT);
	if (error) {
		dmu_tx_abort(tx);
	} else {
		dmu_write(os, ZVOL_OBJ, off, len, data, tx);
		dmu_tx_commit(tx);
	}

	return (error);
}

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

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

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

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

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

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

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

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

/*
 * Delete the entire contents of a directory.  Return a count
 * of the number of entries that could not be deleted. If we encounter
 * an error, return a count of at least one so that the directory stays
 * in the unlinked set.
 *
 * NOTE: this function assumes that the directory is inactive,
 *	so there is no need to lock its entries before deletion.
 *	Also, it assumes the directory contents is *only* regular
 *	files.
 */
static int
zfs_purgedir(znode_t *dzp)
{
	zap_cursor_t	zc;
	zap_attribute_t	zap;
	znode_t		*xzp;
	dmu_tx_t	*tx;
	zfsvfs_t	*zfsvfs = dzp->z_zfsvfs;
	zfs_dirlock_t	dl;
	int skipped = 0;
	int error;

	for (zap_cursor_init(&zc, zfsvfs->z_os, dzp->z_id);
	    (error = zap_cursor_retrieve(&zc, &zap)) == 0;
	    zap_cursor_advance(&zc)) {
		error = zfs_zget(zfsvfs,
		    ZFS_DIRENT_OBJ(zap.za_first_integer), &xzp);
		if (error) {
			skipped += 1;
			continue;
		}

/*
	    ASSERT((ZTOV(xzp)->v_type == VREG) ||
		    (ZTOV(xzp)->v_type == VLNK));
*/

		tx = dmu_tx_create(zfsvfs->z_os);
		dmu_tx_hold_sa(tx, dzp->z_sa_hdl, B_FALSE);
		dmu_tx_hold_zap(tx, dzp->z_id, FALSE, zap.za_name);
		dmu_tx_hold_sa(tx, xzp->z_sa_hdl, B_FALSE);
		dmu_tx_hold_zap(tx, zfsvfs->z_unlinkedobj, FALSE, NULL);
		/* Is this really needed ? */
		zfs_sa_upgrade_txholds(tx, xzp);
		error = dmu_tx_assign(tx, TXG_WAIT);
		if (error) {
			dmu_tx_abort(tx);
			//VN_RELE(ZTOV(xzp)); // async
			VN_RELE_ASYNC(ZTOV(xzp), dsl_pool_vnrele_taskq(dmu_objset_pool(zfsvfs->z_os)));
			skipped += 1;
			continue;
		}
		bzero(&dl, sizeof (dl));
		dl.dl_dzp = dzp;
		dl.dl_name = zap.za_name;

		error = zfs_link_destroy(&dl, xzp, tx, 0, NULL);
		if (error)
			skipped += 1;
		dmu_tx_commit(tx);

		//VN_RELE(ZTOV(xzp)); // async
		VN_RELE_ASYNC(ZTOV(xzp), dsl_pool_vnrele_taskq(dmu_objset_pool(zfsvfs->z_os)));
	}
	zap_cursor_fini(&zc);
	if (error != ENOENT)
		skipped += 1;
	return (skipped);
}

int
zfs_make_xattrdir(znode_t *zp, vattr_t *vap, vnode_t **xvpp, cred_t *cr)
{
	zfsvfs_t *zfsvfs = zp->z_zfsvfs;
	znode_t *xzp;
	dmu_tx_t *tx;
	int error;
	zfs_fuid_info_t *fuidp = NULL;

	*xvpp = NULL;

	/*
	 * In FreeBSD, access checking for creating an EA is being done
	 * in zfs_setextattr(),
	 */
#ifndef __FreeBSD__
	if (error = zfs_zaccess(zp, ACE_WRITE_NAMED_ATTRS, 0, B_FALSE, cr))
		return (error);
#endif

	tx = dmu_tx_create(zfsvfs->z_os);
	dmu_tx_hold_bonus(tx, zp->z_id);
	dmu_tx_hold_zap(tx, DMU_NEW_OBJECT, FALSE, NULL);
	if (IS_EPHEMERAL(crgetuid(cr)) || IS_EPHEMERAL(crgetgid(cr))) {
		if (zfsvfs->z_fuid_obj == 0) {
			dmu_tx_hold_bonus(tx, DMU_NEW_OBJECT);
			dmu_tx_hold_write(tx, DMU_NEW_OBJECT, 0,
			    FUID_SIZE_ESTIMATE(zfsvfs));
			dmu_tx_hold_zap(tx, MASTER_NODE_OBJ, FALSE, NULL);
		} else {
			dmu_tx_hold_bonus(tx, zfsvfs->z_fuid_obj);
			dmu_tx_hold_write(tx, zfsvfs->z_fuid_obj, 0,
			    FUID_SIZE_ESTIMATE(zfsvfs));
		}
	}
	error = dmu_tx_assign(tx, zfsvfs->z_assign);
	if (error) {
		if (error == ERESTART && zfsvfs->z_assign == TXG_NOWAIT)
			dmu_tx_wait(tx);
		dmu_tx_abort(tx);
		return (error);
	}
	zfs_mknode(zp, vap, tx, cr, IS_XATTR, &xzp, 0, NULL, &fuidp);
	ASSERT(xzp->z_phys->zp_parent == zp->z_id);
	dmu_buf_will_dirty(zp->z_dbuf, tx);
	zp->z_phys->zp_xattr = xzp->z_id;

	(void) zfs_log_create(zfsvfs->z_log, tx, TX_MKXATTR, zp,
	    xzp, "", NULL, fuidp, vap);
	if (fuidp)
		zfs_fuid_info_free(fuidp);
	dmu_tx_commit(tx);

	*xvpp = ZTOV(xzp);

	return (0);
}

/*
 * In one tx, free all log blocks and clear the log header.
 * If keep_first is set, then we're replaying a log with no content.
 * We want to keep the first block, however, so that the first
 * synchronous transaction doesn't require a txg_wait_synced()
 * in zil_create().  We don't need to txg_wait_synced() here either
 * when keep_first is set, because both zil_create() and zil_destroy()
 * will wait for any in-progress destroys to complete.
 */
void
zil_destroy(zilog_t *zilog, boolean_t keep_first)
{
	const zil_header_t *zh = zilog->zl_header;
	lwb_t *lwb;
	dmu_tx_t *tx;
	uint64_t txg;

	/*
	 * Wait for any previous destroy to complete.
	 */
	txg_wait_synced(zilog->zl_dmu_pool, zilog->zl_destroy_txg);

	if (BP_IS_HOLE(&zh->zh_log))
		return;

	tx = dmu_tx_create(zilog->zl_os);
	(void) dmu_tx_assign(tx, TXG_WAIT);
	dsl_dataset_dirty(dmu_objset_ds(zilog->zl_os), tx);
	txg = dmu_tx_get_txg(tx);

	mutex_enter(&zilog->zl_lock);

	/*
	 * It is possible for the ZIL to get the previously mounted zilog
	 * structure of the same dataset if quickly remounted and the dbuf
	 * eviction has not completed. In this case we can see a non
	 * empty lwb list and keep_first will be set. We fix this by
	 * clearing the keep_first. This will be slower but it's very rare.
	 */
	if (!list_is_empty(&zilog->zl_lwb_list) && keep_first)
		keep_first = B_FALSE;

	ASSERT3U(zilog->zl_destroy_txg, <, txg);
	zilog->zl_destroy_txg = txg;
	zilog->zl_keep_first = keep_first;

	if (!list_is_empty(&zilog->zl_lwb_list)) {
		ASSERT(zh->zh_claim_txg == 0);
		ASSERT(!keep_first);
		while ((lwb = list_head(&zilog->zl_lwb_list)) != NULL) {
			list_remove(&zilog->zl_lwb_list, lwb);
			if (lwb->lwb_buf != NULL)
				zio_buf_free(lwb->lwb_buf, lwb->lwb_sz);
			zio_free_blk(zilog->zl_spa, &lwb->lwb_blk, txg);
			kmem_cache_free(zil_lwb_cache, lwb);
		}
	} else {
		if (!keep_first) {
			(void) zil_parse(zilog, zil_free_log_block,
			    zil_free_log_record, tx, zh->zh_claim_txg);
		}
	}
	mutex_exit(&zilog->zl_lock);

	dmu_tx_commit(tx);
}

int
zfs_make_xattrdir(znode_t *zp, vattr_t *vap, vnode_t **xvpp, cred_t *cr)
{
	zfsvfs_t *zfsvfs = zp->z_zfsvfs;
	znode_t *xzp;
	dmu_tx_t *tx;
	int error;
	zfs_acl_ids_t acl_ids;
	boolean_t fuid_dirtied;

	*xvpp = NULL;

	if (error = zfs_zaccess(zp, ACE_WRITE_NAMED_ATTRS, 0, B_FALSE, cr))
		return (error);

	if ((error = zfs_acl_ids_create(zp, IS_XATTR, vap, cr, NULL,
	    &acl_ids)) != 0)
		return (error);
	if (zfs_acl_ids_overquota(zfsvfs, &acl_ids)) {
		zfs_acl_ids_free(&acl_ids);
		return (EDQUOT);
	}

	tx = dmu_tx_create(zfsvfs->z_os);
	dmu_tx_hold_bonus(tx, zp->z_id);
	dmu_tx_hold_zap(tx, DMU_NEW_OBJECT, FALSE, NULL);
	fuid_dirtied = zfsvfs->z_fuid_dirty;
	if (fuid_dirtied)
		zfs_fuid_txhold(zfsvfs, tx);
	error = dmu_tx_assign(tx, TXG_NOWAIT);
	if (error) {
		zfs_acl_ids_free(&acl_ids);
		if (error == ERESTART)
			dmu_tx_wait(tx);
		dmu_tx_abort(tx);
		return (error);
	}
	zfs_mknode(zp, vap, tx, cr, IS_XATTR, &xzp, 0, &acl_ids);

	if (fuid_dirtied)
		zfs_fuid_sync(zfsvfs, tx);

	ASSERT(xzp->z_phys->zp_parent == zp->z_id);
	dmu_buf_will_dirty(zp->z_dbuf, tx);
	zp->z_phys->zp_xattr = xzp->z_id;

	(void) zfs_log_create(zfsvfs->z_log, tx, TX_MKXATTR, zp,
	    xzp, "", NULL, acl_ids.z_fuidp, vap);

	zfs_acl_ids_free(&acl_ids);
	dmu_tx_commit(tx);

	*xvpp = ZTOV(xzp);

	return (0);
}

static int
zvol_write(struct bio *bio)
{
	zvol_state_t *zv = bio->bi_bdev->bd_disk->private_data;
	uint64_t offset = BIO_BI_SECTOR(bio) << 9;
	uint64_t size = BIO_BI_SIZE(bio);
	int error = 0;
	dmu_tx_t *tx;
	rl_t *rl;
	uio_t uio;

	if (bio->bi_rw & VDEV_REQ_FLUSH)
		zil_commit(zv->zv_zilog, ZVOL_OBJ);

	/*
	 * Some requests are just for flush and nothing else.
	 */
	if (size == 0)
		goto out;

	uio.uio_bvec = &bio->bi_io_vec[BIO_BI_IDX(bio)];
	uio.uio_skip = BIO_BI_SKIP(bio);
	uio.uio_resid = size;
	uio.uio_iovcnt = bio->bi_vcnt - BIO_BI_IDX(bio);
	uio.uio_loffset = offset;
	uio.uio_limit = MAXOFFSET_T;
	uio.uio_segflg = UIO_BVEC;

	rl = zfs_range_lock(&zv->zv_znode, offset, size, RL_WRITER);

	tx = dmu_tx_create(zv->zv_objset);
	dmu_tx_hold_write(tx, ZVOL_OBJ, offset, size);

	/* This will only fail for ENOSPC */
	error = dmu_tx_assign(tx, TXG_WAIT);
	if (error) {
		dmu_tx_abort(tx);
		zfs_range_unlock(rl);
		goto out;
	}

	error = dmu_write_uio(zv->zv_objset, ZVOL_OBJ, &uio, size, tx);
	if (error == 0)
		zvol_log_write(zv, tx, offset, size,
		    !!(bio->bi_rw & VDEV_REQ_FUA));

	dmu_tx_commit(tx);
	zfs_range_unlock(rl);

	if ((bio->bi_rw & VDEV_REQ_FUA) ||
	    zv->zv_objset->os_sync == ZFS_SYNC_ALWAYS)
		zil_commit(zv->zv_zilog, ZVOL_OBJ);

out:
	return (error);
}

/*
 * Delete the entire contents of a directory.  Return a count
 * of the number of entries that could not be deleted. If we encounter
 * an error, return a count of at least one so that the directory stays
 * in the unlinked set.
 *
 * NOTE: this function assumes that the directory is inactive,
 *	so there is no need to lock its entries before deletion.
 *	Also, it assumes the directory contents is *only* regular
 *	files.
 */
static int
zfs_purgedir(znode_t *dzp)
{
	zap_cursor_t	zc;
	zap_attribute_t	zap;
	znode_t		*xzp;
	dmu_tx_t	*tx;
	zfsvfs_t	*zfsvfs = ZTOZSB(dzp);
	zfs_dirlock_t	dl;
	int skipped = 0;
	int error;

	for (zap_cursor_init(&zc, zfsvfs->z_os, dzp->z_id);
	    (error = zap_cursor_retrieve(&zc, &zap)) == 0;
	    zap_cursor_advance(&zc)) {
		error = zfs_zget(zfsvfs,
		    ZFS_DIRENT_OBJ(zap.za_first_integer), &xzp);
		if (error) {
			skipped += 1;
			continue;
		}

		ASSERT(S_ISREG(ZTOI(xzp)->i_mode) ||
		    S_ISLNK(ZTOI(xzp)->i_mode));

		tx = dmu_tx_create(zfsvfs->z_os);
		dmu_tx_hold_sa(tx, dzp->z_sa_hdl, B_FALSE);
		dmu_tx_hold_zap(tx, dzp->z_id, FALSE, zap.za_name);
		dmu_tx_hold_sa(tx, xzp->z_sa_hdl, B_FALSE);
		dmu_tx_hold_zap(tx, zfsvfs->z_unlinkedobj, FALSE, NULL);
		/* Is this really needed ? */
		zfs_sa_upgrade_txholds(tx, xzp);
		dmu_tx_mark_netfree(tx);
		error = dmu_tx_assign(tx, TXG_WAIT);
		if (error) {
			dmu_tx_abort(tx);
			zfs_iput_async(ZTOI(xzp));
			skipped += 1;
			continue;
		}
		bzero(&dl, sizeof (dl));
		dl.dl_dzp = dzp;
		dl.dl_name = zap.za_name;

		error = zfs_link_destroy(&dl, xzp, tx, 0, NULL);
		if (error)
			skipped += 1;
		dmu_tx_commit(tx);

		zfs_iput_async(ZTOI(xzp));
	}
	zap_cursor_fini(&zc);
	if (error != ENOENT)
		skipped += 1;
	return (skipped);
}

int
zvol_set_volsize(zfs_cmd_t *zc)
{
	zvol_state_t *zv;
	dev_t dev = zc->zc_dev;
	dmu_tx_t *tx;
	int error;
	dmu_object_info_t doi;

	mutex_enter(&zvol_state_lock);

	if ((zv = zvol_minor_lookup(zc->zc_name)) == NULL) {
		mutex_exit(&zvol_state_lock);
		return (ENXIO);
	}

	if ((error = dmu_object_info(zv->zv_objset, ZVOL_OBJ, &doi)) != 0 ||
	    (error = zvol_check_volsize(zc, doi.doi_data_block_size)) != 0) {
		mutex_exit(&zvol_state_lock);
		return (error);
	}

	if (zv->zv_readonly || (zv->zv_mode & DS_MODE_READONLY)) {
		mutex_exit(&zvol_state_lock);
		return (EROFS);
	}

	tx = dmu_tx_create(zv->zv_objset);
	dmu_tx_hold_zap(tx, ZVOL_ZAP_OBJ, TRUE, NULL);
	dmu_tx_hold_free(tx, ZVOL_OBJ, zc->zc_volsize, DMU_OBJECT_END);
	error = dmu_tx_assign(tx, TXG_WAIT);
	if (error) {
		dmu_tx_abort(tx);
		mutex_exit(&zvol_state_lock);
		return (error);
	}

	error = zap_update(zv->zv_objset, ZVOL_ZAP_OBJ, "size", 8, 1,
	    &zc->zc_volsize, tx);
	if (error == 0) {
		error = dmu_free_range(zv->zv_objset, ZVOL_OBJ, zc->zc_volsize,
		    DMU_OBJECT_END, tx);
	}

	dmu_tx_commit(tx);

	if (error == 0) {
		zv->zv_volsize = zc->zc_volsize;
		zvol_size_changed(zv, dev);
	}

	mutex_exit(&zvol_state_lock);

	return (error);
}

/*
 * Delete the entire contents of a directory.  Return a count
 * of the number of entries that could not be deleted. If we encounter
 * an error, return a count of at least one so that the directory stays
 * in the unlinked set.
 *
 * NOTE: this function assumes that the directory is inactive,
 *	so there is no need to lock its entries before deletion.
 *	Also, it assumes the directory contents is *only* regular
 *	files.
 */
static int
zfs_purgedir(znode_t *dzp)
{
	zap_cursor_t	zc;
	zap_attribute_t	zap;
	znode_t		*xzp;
	dmu_tx_t	*tx;
	zfsvfs_t	*zfsvfs = dzp->z_zfsvfs;
	zfs_dirlock_t	dl;
	int skipped = 0;
	int error;

	for (zap_cursor_init(&zc, zfsvfs->z_os, dzp->z_id);
	    (error = zap_cursor_retrieve(&zc, &zap)) == 0;
	    zap_cursor_advance(&zc)) {
		error = zfs_zget(zfsvfs,
		    ZFS_DIRENT_OBJ(zap.za_first_integer), &xzp);
		if (error) {
			skipped += 1;
			continue;
		}

		ASSERT((ZTOV(xzp)->v_type == VREG) ||
		    (ZTOV(xzp)->v_type == VLNK));

		tx = dmu_tx_create(zfsvfs->z_os);
		dmu_tx_hold_bonus(tx, dzp->z_id);
		dmu_tx_hold_zap(tx, dzp->z_id, FALSE, zap.za_name);
		dmu_tx_hold_bonus(tx, xzp->z_id);
		dmu_tx_hold_zap(tx, zfsvfs->z_unlinkedobj, FALSE, NULL);
		error = dmu_tx_assign(tx, TXG_WAIT);
		if (error) {
			dmu_tx_abort(tx);
			VN_RELE(ZTOV(xzp));
			skipped += 1;
			continue;
		}
		bzero(&dl, sizeof (dl));
		dl.dl_dzp = dzp;
		dl.dl_name = zap.za_name;

		error = zfs_link_destroy(&dl, xzp, tx, 0, NULL);
		if (error)
			skipped += 1;
		dmu_tx_commit(tx);

		VN_RELE(ZTOV(xzp));
	}
	zap_cursor_fini(&zc);
	if (error != ENOENT)
		skipped += 1;
	return (skipped);
}

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

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

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

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

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

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

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

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

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

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

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

/*
 * Delete the entire contents of a directory.  Return a count
 * of the number of entries that could not be deleted. If we encounter
 * an error, return a count of at least one so that the directory stays
 * in the unlinked set.
 *
 * NOTE: this function assumes that the directory is inactive,
 *	so there is no need to lock its entries before deletion.
 *	Also, it assumes the directory contents is *only* regular
 *	files.
 */
static int
zfs_purgedir(znode_t *dzp)
{
    zap_cursor_t	zc;
    zap_attribute_t	zap;
    znode_t		*xzp;
    dmu_tx_t	*tx;
    zfsvfs_t	*zfsvfs = dzp->z_zfsvfs;
    int skipped = 0;
    int error;

    for (zap_cursor_init(&zc, zfsvfs->z_os, dzp->z_id);
            (error = zap_cursor_retrieve(&zc, &zap)) == 0;
            zap_cursor_advance(&zc)) {
        error = zfs_zget(zfsvfs,
                         ZFS_DIRENT_OBJ(zap.za_first_integer), &xzp);
        if (error) {
            skipped += 1;
            continue;
        }

        vn_lock(ZTOV(xzp), LK_EXCLUSIVE | LK_RETRY);
        ASSERT((ZTOV(xzp)->v_type == VREG) ||
               (ZTOV(xzp)->v_type == VLNK));

        tx = dmu_tx_create(zfsvfs->z_os);
        dmu_tx_hold_sa(tx, dzp->z_sa_hdl, B_FALSE);
        dmu_tx_hold_zap(tx, dzp->z_id, FALSE, zap.za_name);
        dmu_tx_hold_sa(tx, xzp->z_sa_hdl, B_FALSE);
        dmu_tx_hold_zap(tx, zfsvfs->z_unlinkedobj, FALSE, NULL);
        /* Is this really needed ? */
        zfs_sa_upgrade_txholds(tx, xzp);
        dmu_tx_mark_netfree(tx);
        error = dmu_tx_assign(tx, TXG_WAIT);
        if (error) {
            dmu_tx_abort(tx);
            vput(ZTOV(xzp));
            skipped += 1;
            continue;
        }

        error = zfs_link_destroy(dzp, zap.za_name, xzp, tx, 0, NULL);
        if (error)
            skipped += 1;
        dmu_tx_commit(tx);

        vput(ZTOV(xzp));
    }
    zap_cursor_fini(&zc);
    if (error != ENOENT)
        skipped += 1;
    return (skipped);
}

/*
 * Common write path running under the zvol taskq context.  This function
 * is responsible for copying the request structure data in to the DMU and
 * signaling the request queue with the result of the copy.
 */
static void
zvol_write(void *arg)
{
    struct request *req = (struct request *)arg;
    struct request_queue *q = req->q;
    zvol_state_t *zv = q->queuedata;
    fstrans_cookie_t cookie = spl_fstrans_mark();
    uint64_t offset = blk_rq_pos(req) << 9;
    uint64_t size = blk_rq_bytes(req);
    int error = 0;
    dmu_tx_t *tx;
    rl_t *rl;

    if (req->cmd_flags & VDEV_REQ_FLUSH)
        zil_commit(zv->zv_zilog, ZVOL_OBJ);

    /*
     * Some requests are just for flush and nothing else.
     */
    if (size == 0) {
        error = 0;
        goto out;
    }

    rl = zfs_range_lock(&zv->zv_znode, offset, size, RL_WRITER);

    tx = dmu_tx_create(zv->zv_objset);
    dmu_tx_hold_write(tx, ZVOL_OBJ, offset, size);

    /* This will only fail for ENOSPC */
    error = dmu_tx_assign(tx, TXG_WAIT);
    if (error) {
        dmu_tx_abort(tx);
        zfs_range_unlock(rl);
        goto out;
    }

    error = dmu_write_req(zv->zv_objset, ZVOL_OBJ, req, tx);
    if (error == 0)
        zvol_log_write(zv, tx, offset, size,
                       req->cmd_flags & VDEV_REQ_FUA);

    dmu_tx_commit(tx);
    zfs_range_unlock(rl);

    if ((req->cmd_flags & VDEV_REQ_FUA) ||
            zv->zv_objset->os_sync == ZFS_SYNC_ALWAYS)
        zil_commit(zv->zv_zilog, ZVOL_OBJ);

out:
    blk_end_request(req, -error, size);
    spl_fstrans_unmark(cookie);
}

static int
zfs_vfs_sync(struct mount *mp, __unused int waitfor, __unused vfs_context_t context)
{
	zfsvfs_t *zfsvfs = vfs_fsprivate(mp);

	ZFS_ENTER(zfsvfs);

	/*
	 * Mac OS X needs a file system modify time
	 *
	 * We use the mtime of the "com.apple.system.mtime" 
	 * extended attribute, which is associated with the
	 * file system root directory.
	 *
	 * Here we sync any mtime changes to this attribute.
	 */
	if (zfsvfs->z_mtime_vp != NULL) {
		timestruc_t  mtime;
		znode_t  *zp;
top:
		zp = VTOZ(zfsvfs->z_mtime_vp);
		ZFS_TIME_DECODE(&mtime, zp->z_phys->zp_mtime);
		if (zfsvfs->z_last_mtime_synced < mtime.tv_sec) {
			dmu_tx_t  *tx;
			int  error;

			tx = dmu_tx_create(zfsvfs->z_os);
			dmu_tx_hold_bonus(tx, zp->z_id);
			error = dmu_tx_assign(tx, zfsvfs->z_assign);
			if (error) {
				if (error == ERESTART && zfsvfs->z_assign == TXG_NOWAIT) {
					dmu_tx_wait(tx);
					dmu_tx_abort(tx);
					goto top;
				}
				dmu_tx_abort(tx);
			} else {
				dmu_buf_will_dirty(zp->z_dbuf, tx);
				dmu_tx_commit(tx);
				zfsvfs->z_last_mtime_synced = mtime.tv_sec;
			}
		}
	}

	if (zfsvfs->z_log != NULL)
		zil_commit(zfsvfs->z_log, UINT64_MAX, 0);
	else
		txg_wait_synced(dmu_objset_pool(zfsvfs->z_os), 0);
	ZFS_EXIT(zfsvfs);

	return (0);
}