Function dmu_objset_open_impl

freebsd/contrib/openzfs/module/zfs/dmu_objset.c:410–640

* Instantiates the objset_t in-memory structure corresponding to the * objset_phys_t that's pointed to by the specified blkptr_t. */

 * objset_phys_t that's pointed to by the specified blkptr_t.
 */
int
dmu_objset_open_impl(spa_t *spa, dsl_dataset_t *ds, blkptr_t *bp,
    objset_t **osp)
{
	objset_t *os;
	int i, err;

	ASSERT(ds == NULL || MUTEX_HELD(&ds->ds_opening_lock));
	ASSERT(!BP_IS_REDACTED(bp));

	/*
	 * We need the pool config lock to get properties.
	 */
	ASSERT(ds == NULL || dsl_pool_config_held(ds->ds_dir->dd_pool));

	/*
	 * The $ORIGIN dataset (if it exists) doesn't have an associated
	 * objset, so there's no reason to open it. The $ORIGIN dataset
	 * will not exist on pools older than SPA_VERSION_ORIGIN.
	 */
	if (ds != NULL && spa_get_dsl(spa) != NULL &&
	    spa_get_dsl(spa)->dp_origin_snap != NULL) {
		ASSERT3P(ds->ds_dir, !=,
		    spa_get_dsl(spa)->dp_origin_snap->ds_dir);
	}

	os = kmem_zalloc(sizeof (objset_t), KM_SLEEP);
	os->os_dsl_dataset = ds;
	os->os_spa = spa;
	os->os_rootbp = bp;
	if (!BP_IS_HOLE(os->os_rootbp)) {
		arc_flags_t aflags = ARC_FLAG_WAIT;
		zbookmark_phys_t zb;
		int size;
		enum zio_flag zio_flags = ZIO_FLAG_CANFAIL;
		SET_BOOKMARK(&zb, ds ? ds->ds_object : DMU_META_OBJSET,
		    ZB_ROOT_OBJECT, ZB_ROOT_LEVEL, ZB_ROOT_BLKID);

		if (DMU_OS_IS_L2CACHEABLE(os))
			aflags |= ARC_FLAG_L2CACHE;

		if (ds != NULL && ds->ds_dir->dd_crypto_obj != 0) {
			ASSERT3U(BP_GET_COMPRESS(bp), ==, ZIO_COMPRESS_OFF);
			ASSERT(BP_IS_AUTHENTICATED(bp));
			zio_flags |= ZIO_FLAG_RAW;
		}

		dprintf_bp(os->os_rootbp, "reading %s", "");
		err = arc_read(NULL, spa, os->os_rootbp,
		    arc_getbuf_func, &os->os_phys_buf,
		    ZIO_PRIORITY_SYNC_READ, zio_flags, &aflags, &zb);
		if (err != 0) {
			kmem_free(os, sizeof (objset_t));
			/* convert checksum errors into IO errors */
			if (err == ECKSUM)
				err = SET_ERROR(EIO);
			return (err);
		}