diff --git a/kernel-shared/zoned.c b/kernel-shared/zoned.c
index 6894d421..28423118 100644
--- a/kernel-shared/zoned.c
+++ b/kernel-shared/zoned.c
@@ -648,6 +648,67 @@ u64 btrfs_find_allocatable_zones(struct btrfs_device *device, u64 hole_start,
 	return pos;
 }
 
+/*
+ * Calculate an allocation pointer from the extent allocation information
+ * for a block group consisting of conventional zones. It is pointed to the
+ * end of the highest addressed extent in the block group as an allocation
+ * offset.
+ */
+static int calculate_alloc_pointer(struct btrfs_fs_info *fs_info,
+				   struct btrfs_block_group *cache,
+				   u64 *offset_ret)
+{
+	struct btrfs_root *root = fs_info->extent_root;
+	struct btrfs_path *path;
+	struct btrfs_key key;
+	struct btrfs_key found_key;
+	int ret;
+	u64 length;
+
+	path = btrfs_alloc_path();
+	if (!path)
+		return -ENOMEM;
+
+	key.objectid = cache->start + cache->length;
+	key.type = 0;
+	key.offset = 0;
+
+	ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
+	/* There should be no exact match (ie. an extent) at this address */
+	if (!ret)
+		ret = -EUCLEAN;
+	if (ret < 0)
+		goto out;
+
+	ret = btrfs_previous_extent_item(root, path, cache->start);
+	if (ret) {
+		if (ret == 1) {
+			ret = 0;
+			*offset_ret = 0;
+		}
+		goto out;
+	}
+
+	btrfs_item_key_to_cpu(path->nodes[0], &found_key, path->slots[0]);
+
+	if (found_key.type == BTRFS_EXTENT_ITEM_KEY)
+		length = found_key.offset;
+	else
+		length = fs_info->nodesize;
+
+	if (!(found_key.objectid >= cache->start &&
+	       found_key.objectid + length <= cache->start + cache->length)) {
+		ret = -EUCLEAN;
+		goto out;
+	}
+	*offset_ret = found_key.objectid + length - cache->start;
+	ret = 0;
+
+out:
+	btrfs_free_path(path);
+	return ret;
+}
+
 int btrfs_load_block_group_zone_info(struct btrfs_fs_info *fs_info,
 				     struct btrfs_block_group *cache)
 {
@@ -661,6 +722,7 @@ int btrfs_load_block_group_zone_info(struct btrfs_fs_info *fs_info,
 	int ret = 0;
 	int i;
 	u64 *alloc_offsets = NULL;
+	u64 last_alloc = 0;
 	u32 num_sequential = 0, num_conventional = 0;
 
 	if (!btrfs_is_zoned(fs_info))
@@ -746,12 +808,16 @@ int btrfs_load_block_group_zone_info(struct btrfs_fs_info *fs_info,
 	}
 
 	if (num_conventional > 0) {
-		/*
-		 * Since conventional zones do not have a write pointer, we
-		 * cannot determine alloc_offset from the pointer
-		 */
-		ret = -EINVAL;
-		goto out;
+		ret = calculate_alloc_pointer(fs_info, cache, &last_alloc);
+		if (ret || map->num_stripes == num_conventional) {
+			if (!ret)
+				cache->alloc_offset = last_alloc;
+			else
+				error(
+		"zoned: failed to determine allocation offset of block group %llu",
+					  cache->start);
+			goto out;
+		}
 	}
 
 	switch (map->type & BTRFS_BLOCK_GROUP_PROFILE_MASK) {
@@ -773,6 +839,14 @@ int btrfs_load_block_group_zone_info(struct btrfs_fs_info *fs_info,
 	}
 
 out:
+	/* An extent is allocated after the write pointer */
+	if (!ret && num_conventional && last_alloc > cache->alloc_offset) {
+		error(
+		"zoned: got wrong write pointer in block group %llu: %llu > %llu",
+		      logical, last_alloc, cache->alloc_offset);
+		ret = -EIO;
+	}
+
 	free(alloc_offsets);
 	return ret;
 }