+static bool erase_raw(struct exfat* ef, size_t size, off_t offset)
+{
+ if (exfat_pwrite(ef->dev, ef->zero_cluster, size, offset) < 0)
+ {
+ exfat_error("failed to erase %zu bytes at %"PRId64, size, offset);
+ return false;
+ }
+ return true;
+}
+
+static int erase_range(struct exfat* ef, struct exfat_node* node,
+ uint64_t begin, uint64_t end)
+{
+ uint64_t cluster_boundary;
+ cluster_t cluster;
+
+ if (begin >= end)
+ return 0;
+
+ cluster_boundary = (begin | (CLUSTER_SIZE(*ef->sb) - 1)) + 1;
+ cluster = exfat_advance_cluster(ef, node,
+ begin / CLUSTER_SIZE(*ef->sb));
+ if (CLUSTER_INVALID(cluster))
+ {
+ exfat_error("invalid cluster 0x%x while erasing", cluster);
+ return -EIO;
+ }
+ /* erase from the beginning to the closest cluster boundary */
+ if (!erase_raw(ef, MIN(cluster_boundary, end) - begin,
+ exfat_c2o(ef, cluster) + begin % CLUSTER_SIZE(*ef->sb)))
+ return -EIO;
+ /* erase whole clusters */
+ while (cluster_boundary < end)
+ {
+ cluster = exfat_next_cluster(ef, node, cluster);
+ /* the cluster cannot be invalid because we have just allocated it */
+ if (CLUSTER_INVALID(cluster))
+ exfat_bug("invalid cluster 0x%x after allocation", cluster);
+ if (!erase_raw(ef, CLUSTER_SIZE(*ef->sb), exfat_c2o(ef, cluster)))
+ return -EIO;
+ cluster_boundary += CLUSTER_SIZE(*ef->sb);
+ }
+ return 0;
+}
+
+int exfat_truncate(struct exfat* ef, struct exfat_node* node, uint64_t size,
+ bool erase)