C++ dmu_objset_disown函数代码示例

/* ARGSUSED */
static int
object_from_path(const char *dataset, const char *path, struct stat64 *statbuf,
    zinject_record_t *record)
{
	objset_t *os;
	int err;

	/*
	 * Before doing any libzpool operations, call sync() to ensure that the
	 * on-disk state is consistent with the in-core state.
	 */
	sync();

	err = dmu_objset_own(dataset, DMU_OST_ZFS, B_TRUE, FTAG, &os);
	if (err != 0) {
		(void) fprintf(stderr, "cannot open dataset '%s': %s\n",
		    dataset, strerror(err));
		return (-1);
	}

	record->zi_objset = dmu_objset_id(os);
	record->zi_object = statbuf->st_ino;

	dmu_objset_disown(os, FTAG);

	return (0);
}

/*ARGSUSED*/
int
zfs_umount(struct super_block *sb)
{
	zfs_sb_t *zsb = sb->s_fs_info;
	objset_t *os;

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

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

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

	zfs_sb_free(zsb);
	return (0);
}

static void
zvol_last_close(zvol_state_t *zv)
{
    zil_close(zv->zv_zilog);
    zv->zv_zilog = NULL;
    dmu_buf_rele(zv->zv_dbuf, zvol_tag);
    zv->zv_dbuf = NULL;
    dmu_objset_disown(zv->zv_objset, zvol_tag);
    zv->zv_objset = NULL;
}

/*
 * Block out VFS ops and close zfs_sb_t
 *
 * Note, if successful, then we return with the 'z_teardown_lock' and
 * 'z_teardown_inactive_lock' write held.
 */
int
zfs_suspend_fs(zfs_sb_t *zsb)
{
	int error;

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

	dmu_objset_disown(zsb->z_os, zsb);

	return (0);
}

/*
 * Set ZFS_PROP_VOLSIZE set entry point.
 */
int
zvol_set_volsize(const char *name, uint64_t volsize)
{
	zvol_state_t *zv = NULL;
	objset_t *os = NULL;
	int error;
	dmu_object_info_t *doi;
	uint64_t readonly;
	boolean_t owned = B_FALSE;

	error = dsl_prop_get_integer(name,
	    zfs_prop_to_name(ZFS_PROP_READONLY), &readonly, NULL);
	if (error != 0)
		return (SET_ERROR(error));
	if (readonly)
		return (SET_ERROR(EROFS));

	mutex_enter(&zvol_state_lock);
	zv = zvol_find_by_name(name);

	if (zv == NULL || zv->zv_objset == NULL) {
		if ((error = dmu_objset_own(name, DMU_OST_ZVOL, B_FALSE,
		    FTAG, &os)) != 0) {
			mutex_exit(&zvol_state_lock);
			return (SET_ERROR(error));
		}
		owned = B_TRUE;
		if (zv != NULL)
			zv->zv_objset = os;
	} else {
		os = zv->zv_objset;
	}

	doi = kmem_alloc(sizeof (dmu_object_info_t), KM_SLEEP);

	if ((error = dmu_object_info(os, ZVOL_OBJ, doi)) ||
	    (error = zvol_check_volsize(volsize, doi->doi_data_block_size)))
		goto out;

	error = zvol_update_volsize(volsize, os);
	kmem_free(doi, sizeof (dmu_object_info_t));

	if (error == 0 && zv != NULL)
		error = zvol_update_live_volsize(zv, volsize);
out:
	if (owned) {
		dmu_objset_disown(os, FTAG);
		if (zv != NULL)
			zv->zv_objset = NULL;
	}
	mutex_exit(&zvol_state_lock);
	return (error);
}

/* called from zpl */
int
dmu_objset_own(const char *name, dmu_objset_type_t type,
    boolean_t readonly, void *tag, objset_t **osp)
{
	dsl_dataset_t *ds;
	int err;

	err = dsl_dataset_own(name, B_FALSE, tag, &ds);
	if (err)
		return (err);

	err = dmu_objset_from_ds(ds, osp);
	if (err) {
		dsl_dataset_disown(ds, tag);
	} else if (type != DMU_OST_ANY && type != (*osp)->os_phys->os_type) {
		dmu_objset_disown(*osp, tag);
		return (EINVAL);
	} else if (!readonly && dsl_dataset_is_snapshot(ds)) {
		dmu_objset_disown(*osp, tag);
		return (EROFS);
	}
	return (err);
}

static void
zpios_remove_objset(run_args_t *run_args)
{
	zpios_time_t *t = &(run_args->stats.rm_time);
	zpios_region_t *region;
	char name[32];
	int rc = 0, i;

	(void)zpios_upcall(run_args->pre, PHASE_PRE_REMOVE, run_args, 0);
	t->start = zpios_timespec_now();

	(void)snprintf(name, 32, "%s/id_%d", run_args->pool, run_args->id);

	if (run_args->flags & DMU_REMOVE) {
		if (run_args->flags & DMU_FPP) {
			for (i = 0; i < run_args->region_count; i++) {
				region = &run_args->regions[i];
				rc = zpios_dmu_object_free(run_args,
							   region->obj.os,
							   region->obj.obj);
				if (rc)
					zpios_print(run_args->file, "Error "
						    "removing object %d, %d\n",
					            (int)region->obj.obj, rc);
			}
		} else {
			region = &run_args->regions[0];
			rc = zpios_dmu_object_free(run_args,
						   region->obj.os,
						   region->obj.obj);
			if (rc)
				zpios_print(run_args->file, "Error "
					    "removing object %d, %d\n",
				            (int)region->obj.obj, rc);
		}
	}

	dmu_objset_disown(run_args->os, zpios_tag);

	if (run_args->flags & DMU_REMOVE) {
		rc = dsl_destroy_head(name);
		if (rc)
			zpios_print(run_args->file, "Error dsl_destroy_head"
				    "(%s, ...) failed: %d\n", name, rc);
	}

	t->stop  = zpios_timespec_now();
	t->delta = zpios_timespec_sub(t->stop, t->start);
	(void)zpios_upcall(run_args->post, PHASE_POST_REMOVE, run_args, rc);
}

static void
zvol_last_close(zvol_state_t *zv)
{
	zil_close(zv->zv_zilog);
	zv->zv_zilog = NULL;

	dmu_buf_rele(zv->zv_dbuf, zvol_tag);
	zv->zv_dbuf = NULL;

	/*
	 * Evict cached data
	 */
	if (dsl_dataset_is_dirty(dmu_objset_ds(zv->zv_objset)) &&
	    !(zv->zv_flags & ZVOL_RDONLY))
		txg_wait_synced(dmu_objset_pool(zv->zv_objset), 0);
	(void) dmu_objset_evict_dbufs(zv->zv_objset);

	dmu_objset_disown(zv->zv_objset, zvol_tag);
	zv->zv_objset = NULL;
}

/*
 * When we are called, os MUST refer to an objset associated with a dataset
 * that is owned by 'tag'; that is, is held and long held by 'tag' and ds_owner
 * == tag.  We will then release and reacquire ownership of the dataset while
 * holding the pool config_rwlock to avoid intervening namespace or ownership
 * changes may occur.
 *
 * This exists solely to accommodate zfs_ioc_userspace_upgrade()'s desire to
 * release the hold on its dataset and acquire a new one on the dataset of the
 * same name so that it can be partially torn down and reconstructed.
 */
void
dmu_objset_refresh_ownership(objset_t *os, void *tag)
{
	dsl_pool_t *dp;
	dsl_dataset_t *ds, *newds;
	char name[MAXNAMELEN];

	ds = os->os_dsl_dataset;
	VERIFY3P(ds, !=, NULL);
	VERIFY3P(ds->ds_owner, ==, tag);
	VERIFY(dsl_dataset_long_held(ds));

	dsl_dataset_name(ds, name);
	dp = dmu_objset_pool(os);
	dsl_pool_config_enter(dp, FTAG);
	dmu_objset_disown(os, tag);
	VERIFY0(dsl_dataset_own(dp, name, tag, &newds));
	VERIFY3P(newds, ==, os->os_dsl_dataset);
	dsl_pool_config_exit(dp, FTAG);
}

//.........这里部分代码省略.........

	rel = fullpath + strlen(mp.mnt_mountp);
	if (rel[0] == '/')
		rel++;
	(void) strcpy(relpath, rel);

	return (0);
}
#endif

//From FreeBSD
static int
parse_pathname(const char *inpath, char *dataset, char *relpath,
    struct stat *statbuf)
{
        struct statfs sfs;
        const char *rel;
        char fullpath[MAXPATHLEN];

        compress_slashes(inpath, fullpath);

        if (fullpath[0] != '/') {
                (void) fprintf(stderr, "invalid object '%s': must be full "
                    "path\n", fullpath);
                usage();
                return (-1);
        }

        if (strlen(fullpath) >= MAXPATHLEN) {
                (void) fprintf(stderr, "invalid object; pathname too long\n");
                return (-1);
        }

        if (stat(fullpath, statbuf) != 0) {
                (void) fprintf(stderr, "cannot open '%s': %s\n",
                    fullpath, strerror(errno));
                return (-1);
        }

        if (statfs(fullpath, &sfs) == -1) {
                (void) fprintf(stderr, "cannot find mountpoint for '%s': %s\n",
                    fullpath, strerror(errno));
                return (-1);
        }

        if (strcmp(sfs.f_fstypename, MNTTYPE_ZFS) != 0) {
                (void) fprintf(stderr, "invalid path '%s': not a ZFS "
                    "filesystem\n", fullpath);
                return (-1);
        }

        if (strncmp(fullpath, sfs.f_mntonname, strlen(sfs.f_mntonname)) != 0) {
                (void) fprintf(stderr, "invalid path '%s': mountpoint "
                    "doesn't match path\n", fullpath);
                return (-1);
        }

        (void) strcpy(dataset, sfs.f_mntfromname);

        rel = fullpath + strlen(sfs.f_mntonname);
        if (rel[0] == '/')
                rel++;
        (void) strcpy(relpath, rel);

        return (0);
}

/*
 * Convert from a (dataset, path) pair into a (objset, object) pair.  Note that
 * we grab the object number from the inode number, since looking this up via
 * libzpool is a real pain.
 */
/* ARGSUSED */
static int
object_from_path(const char *dataset, const char *path, struct stat *statbuf,
    zinject_record_t *record)
{
	objset_t *os;
	int err;

	/*
	 * Before doing any libzpool operations, call sync() to ensure that the
	 * on-disk state is consistent with the in-core state.
	 */
	sync();

	err = dmu_objset_own(dataset, DMU_OST_ZFS, B_TRUE, B_FALSE, FTAG, &os);
	if (err != 0) {
		(void) fprintf(stderr, "cannot open dataset '%s': %s\n",
		    dataset, strerror(err));
		return (-1);
	}

	record->zi_objset = dmu_objset_id(os);
	record->zi_object = statbuf->st_ino;

	dmu_objset_disown(os, B_FALSE, FTAG);

	return (0);
}

/*
 * Create a block device minor node and setup the linkage between it
 * and the specified volume.  Once this function returns the block
 * device is live and ready for use.
 */
static int
zvol_create_minor_impl(const char *name)
{
	zvol_state_t *zv;
	objset_t *os;
	dmu_object_info_t *doi;
	uint64_t volsize;
	uint64_t len;
	unsigned minor = 0;
	int error = 0;

	mutex_enter(&zvol_state_lock);

	zv = zvol_find_by_name(name);
	if (zv) {
		error = SET_ERROR(EEXIST);
		goto out;
	}

	doi = kmem_alloc(sizeof (dmu_object_info_t), KM_SLEEP);

	error = dmu_objset_own(name, DMU_OST_ZVOL, B_TRUE, zvol_tag, &os);
	if (error)
		goto out_doi;

	error = dmu_object_info(os, ZVOL_OBJ, doi);
	if (error)
		goto out_dmu_objset_disown;

	error = zap_lookup(os, ZVOL_ZAP_OBJ, "size", 8, 1, &volsize);
	if (error)
		goto out_dmu_objset_disown;

	error = zvol_find_minor(&minor);
	if (error)
		goto out_dmu_objset_disown;

	zv = zvol_alloc(MKDEV(zvol_major, minor), name);
	if (zv == NULL) {
		error = SET_ERROR(EAGAIN);
		goto out_dmu_objset_disown;
	}

	if (dmu_objset_is_snapshot(os))
		zv->zv_flags |= ZVOL_RDONLY;

	zv->zv_volblocksize = doi->doi_data_block_size;
	zv->zv_volsize = volsize;
	zv->zv_objset = os;

	set_capacity(zv->zv_disk, zv->zv_volsize >> 9);

	blk_queue_max_hw_sectors(zv->zv_queue, (DMU_MAX_ACCESS / 4) >> 9);
	blk_queue_max_segments(zv->zv_queue, UINT16_MAX);
	blk_queue_max_segment_size(zv->zv_queue, UINT_MAX);
	blk_queue_physical_block_size(zv->zv_queue, zv->zv_volblocksize);
	blk_queue_io_opt(zv->zv_queue, zv->zv_volblocksize);
	blk_queue_max_discard_sectors(zv->zv_queue,
	    (zvol_max_discard_blocks * zv->zv_volblocksize) >> 9);
	blk_queue_discard_granularity(zv->zv_queue, zv->zv_volblocksize);
	queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, zv->zv_queue);
#ifdef QUEUE_FLAG_NONROT
	queue_flag_set_unlocked(QUEUE_FLAG_NONROT, zv->zv_queue);
#endif
#ifdef QUEUE_FLAG_ADD_RANDOM
	queue_flag_clear_unlocked(QUEUE_FLAG_ADD_RANDOM, zv->zv_queue);
#endif

	if (spa_writeable(dmu_objset_spa(os))) {
		if (zil_replay_disable)
			zil_destroy(dmu_objset_zil(os), B_FALSE);
		else
			zil_replay(os, zv, zvol_replay_vector);
	}

	/*
	 * When udev detects the addition of the device it will immediately
	 * invoke blkid(8) to determine the type of content on the device.
	 * Prefetching the blocks commonly scanned by blkid(8) will speed
	 * up this process.
	 */
	len = MIN(MAX(zvol_prefetch_bytes, 0), SPA_MAXBLOCKSIZE);
	if (len > 0) {
		dmu_prefetch(os, ZVOL_OBJ, 0, 0, len, ZIO_PRIORITY_SYNC_READ);
		dmu_prefetch(os, ZVOL_OBJ, 0, volsize - len, len,
			ZIO_PRIORITY_SYNC_READ);
	}

	zv->zv_objset = NULL;
out_dmu_objset_disown:
	dmu_objset_disown(os, zvol_tag);
out_doi:
	kmem_free(doi, sizeof (dmu_object_info_t));
out:

//.........这里部分代码省略.........

static int
zvol_first_open(zvol_state_t *zv)
{
	objset_t *os;
	uint64_t volsize;
	int locked = 0;
	int error;
	uint64_t ro;

	/*
	 * In all other cases the spa_namespace_lock is taken before the
	 * bdev->bd_mutex lock.  But in this case the Linux __blkdev_get()
	 * function calls fops->open() with the bdev->bd_mutex lock held.
	 *
	 * To avoid a potential lock inversion deadlock we preemptively
	 * try to take the spa_namespace_lock().  Normally it will not
	 * be contended and this is safe because spa_open_common() handles
	 * the case where the caller already holds the spa_namespace_lock.
	 *
	 * When it is contended we risk a lock inversion if we were to
	 * block waiting for the lock.  Luckily, the __blkdev_get()
	 * function allows us to return -ERESTARTSYS which will result in
	 * bdev->bd_mutex being dropped, reacquired, and fops->open() being
	 * called again.  This process can be repeated safely until both
	 * locks are acquired.
	 */
	if (!mutex_owned(&spa_namespace_lock)) {
		locked = mutex_tryenter(&spa_namespace_lock);
		if (!locked)
			return (-ERESTARTSYS);
	}

	/* lie and say we're read-only */
	error = dmu_objset_own(zv->zv_name, DMU_OST_ZVOL, 1, zvol_tag, &os);
	if (error)
		goto out_mutex;

	error = zap_lookup(os, ZVOL_ZAP_OBJ, "size", 8, 1, &volsize);
	if (error) {
		dmu_objset_disown(os, zvol_tag);
		goto out_mutex;
	}

	zv->zv_objset = os;
	error = dmu_bonus_hold(os, ZVOL_OBJ, zvol_tag, &zv->zv_dbuf);
	if (error) {
		dmu_objset_disown(os, zvol_tag);
		goto out_mutex;
	}

	set_capacity(zv->zv_disk, volsize >> 9);
	zv->zv_volsize = volsize;
	zv->zv_zilog = zil_open(os, zvol_get_data);

	VERIFY(dsl_prop_get_integer(zv->zv_name, "readonly", &ro, NULL) == 0);
	if (ro || dmu_objset_is_snapshot(os) ||
	    !spa_writeable(dmu_objset_spa(os))) {
		set_disk_ro(zv->zv_disk, 1);
		zv->zv_flags |= ZVOL_RDONLY;
	} else {
		set_disk_ro(zv->zv_disk, 0);
		zv->zv_flags &= ~ZVOL_RDONLY;
	}

out_mutex:
	if (locked)
		mutex_exit(&spa_namespace_lock);

	return (-error);
}

//.........这里部分代码省略.........
	zsb->z_case = (uint_t)zval;

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

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

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

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

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

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

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

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

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

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

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

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

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

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

	zsb->z_hold_mtx = vmem_zalloc(sizeof (kmutex_t) * ZFS_OBJ_MTX_SZ,
	    KM_SLEEP);
	for (i = 0; i != ZFS_OBJ_MTX_SZ; i++)
		mutex_init(&zsb->z_hold_mtx[i], NULL, MUTEX_DEFAULT, NULL);

	*zsbp = zsb;
	return (0);

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

	vmem_free(zsb->z_hold_mtx, sizeof (kmutex_t) * ZFS_OBJ_MTX_SZ);
	kmem_free(zsb, sizeof (zfs_sb_t));
	return (error);
}

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

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

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

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

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

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

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

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

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

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

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

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

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

	zsb->z_arc_prune = arc_add_prune_callback(zpl_prune_sb, sb);
out:
	if (error) {
		dmu_objset_disown(zsb->z_os, zsb);
		zfs_sb_free(zsb);
	}

	return (error);
}

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

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

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

	zsb->z_sb = sb;
	sb->s_fs_info = zsb;
	sb->s_magic = ZFS_SUPER_MAGIC;
	sb->s_maxbytes = MAX_LFS_FILESIZE;
	sb->s_time_gran = 1;
	sb->s_blocksize = recordsize;
	sb->s_blocksize_bits = ilog2(recordsize);

#ifdef HAVE_BDI
	/*
	 * 2.6.32 API change,
	 * Added backing_device_info (BDI) per super block interfaces.  A BDI
	 * must be configured when using a non-device backed filesystem for
	 * proper writeback.  This is not required for older pdflush kernels.
	 *
	 * NOTE: Linux read-ahead is disabled in favor of zfs read-ahead.
	 */
	zsb->z_bdi.ra_pages = 0;
	sb->s_bdi = &zsb->z_bdi;

	error = -bdi_setup_and_register(&zsb->z_bdi, "zfs", BDI_CAP_MAP_COPY);
	if (error)
		goto out;
#endif /* HAVE_BDI */

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

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

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

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

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

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

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

	if (!zsb->z_issnap)
		zfsctl_create(zsb);
out:
	if (error) {
		dmu_objset_disown(zsb->z_os, zsb);
		zfs_sb_free(zsb);
	}

	return (error);
}