+
+/**
+ * Check whether [offset, offset + bytes) overlaps with the cached
+ * block-status data region.
+ *
+ * If so, and @pnum is not NULL, set *pnum to `bsc.data_end - offset`,
+ * which is what bdrv_bsc_is_data()'s interface needs.
+ * Otherwise, *pnum is not touched.
+ */
+static bool bdrv_bsc_range_overlaps_locked(BlockDriverState *bs,
+ int64_t offset, int64_t bytes,
+ int64_t *pnum)
+{
+ BdrvBlockStatusCache *bsc = qatomic_rcu_read(&bs->block_status_cache);
+ bool overlaps;
+
+ overlaps =
+ qatomic_read(&bsc->valid) &&
+ ranges_overlap(offset, bytes, bsc->data_start,
+ bsc->data_end - bsc->data_start);
+
+ if (overlaps && pnum) {
+ *pnum = bsc->data_end - offset;
+ }
+
+ return overlaps;
+}
+
+/**
+ * See block_int.h for this function's documentation.
+ */
+bool bdrv_bsc_is_data(BlockDriverState *bs, int64_t offset, int64_t *pnum)
+{
+ RCU_READ_LOCK_GUARD();
+
+ return bdrv_bsc_range_overlaps_locked(bs, offset, 1, pnum);
+}
+
+/**
+ * See block_int.h for this function's documentation.
+ */
+void bdrv_bsc_invalidate_range(BlockDriverState *bs,
+ int64_t offset, int64_t bytes)
+{
+ RCU_READ_LOCK_GUARD();
+
+ if (bdrv_bsc_range_overlaps_locked(bs, offset, bytes, NULL)) {
+ qatomic_set(&bs->block_status_cache->valid, false);
+ }
+}
+
+/**
+ * See block_int.h for this function's documentation.
+ */
+void bdrv_bsc_fill(BlockDriverState *bs, int64_t offset, int64_t bytes)
+{
+ BdrvBlockStatusCache *new_bsc = g_new(BdrvBlockStatusCache, 1);
+ BdrvBlockStatusCache *old_bsc;
+
+ *new_bsc = (BdrvBlockStatusCache) {
+ .valid = true,
+ .data_start = offset,
+ .data_end = offset + bytes,
+ };
+
+ QEMU_LOCK_GUARD(&bs->bsc_modify_lock);
+
+ old_bsc = qatomic_rcu_read(&bs->block_status_cache);
+ qatomic_rcu_set(&bs->block_status_cache, new_bsc);
+ if (old_bsc) {
+ g_free_rcu(old_bsc, rcu);
+ }
+}