Function dbuf_read_impl

freebsd/contrib/openzfs/module/zfs/dbuf.c:1437–1533

* Drops db_mtx and the parent lock specified by dblt and tag before * returning. */

 * returning.
 */
static int
dbuf_read_impl(dmu_buf_impl_t *db, zio_t *zio, uint32_t flags,
    db_lock_type_t dblt, void *tag)
{
	dnode_t *dn;
	zbookmark_phys_t zb;
	uint32_t aflags = ARC_FLAG_NOWAIT;
	int err, zio_flags;
	boolean_t bonus_read;

	err = zio_flags = 0;
	bonus_read = B_FALSE;
	DB_DNODE_ENTER(db);
	dn = DB_DNODE(db);
	ASSERT(!zfs_refcount_is_zero(&db->db_holds));
	ASSERT(MUTEX_HELD(&db->db_mtx));
	ASSERT(db->db_state == DB_UNCACHED);
	ASSERT(db->db_buf == NULL);
	ASSERT(db->db_parent == NULL ||
	    RW_LOCK_HELD(&db->db_parent->db_rwlock));

	if (db->db_blkid == DMU_BONUS_BLKID) {
		err = dbuf_read_bonus(db, dn, flags);
		goto early_unlock;
	}

	err = dbuf_read_hole(db, dn, flags);
	if (err == 0)
		goto early_unlock;

	/*
	 * Any attempt to read a redacted block should result in an error. This
	 * will never happen under normal conditions, but can be useful for
	 * debugging purposes.
	 */
	if (BP_IS_REDACTED(db->db_blkptr)) {
		ASSERT(dsl_dataset_feature_is_active(
		    db->db_objset->os_dsl_dataset,
		    SPA_FEATURE_REDACTED_DATASETS));
		err = SET_ERROR(EIO);
		goto early_unlock;
	}

	SET_BOOKMARK(&zb, dmu_objset_id(db->db_objset),
	    db->db.db_object, db->db_level, db->db_blkid);

	/*
	 * All bps of an encrypted os should have the encryption bit set.
	 * If this is not true it indicates tampering and we report an error.
	 */
	if (db->db_objset->os_encrypted && !BP_USES_CRYPT(db->db_blkptr)) {
		spa_log_error(db->db_objset->os_spa, &zb);
		zfs_panic_recover("unencrypted block in encrypted "
		    "object set %llu", dmu_objset_id(db->db_objset));
		err = SET_ERROR(EIO);
		goto early_unlock;
	}