Proposal: Add support for disks with custom block ops

tools/lkl/cptofs.c

@@ -528,6 +528,8 @@ int main(int argc, char **argv)
 		goto out;
 	}
 
+	disk.ops = NULL;
+
 	ret = lkl_disk_add(&disk);
 	if (ret < 0) {
 		fprintf(stderr, "can't add disk: %s\n", lkl_strerror(ret));

tools/lkl/fs2tar.c

@@ -358,6 +358,8 @@ int main(int argc, char **argv)
 		goto out;
 	}
 
+	disk.ops = NULL;
+
 	ret = lkl_disk_add(&disk);
 	if (ret < 0) {
 		fprintf(stderr, "can't add disk: %s\n", lkl_strerror(ret));

tools/lkl/include/lkl.h

@@ -84,6 +84,11 @@ const char *lkl_strerror(int err);
  */
 void lkl_perror(char *msg, int err);
 
+/**
+ * struct lkl_dev_blk_ops - block device host operations, defined in lkl_host.h.
+ */
+struct lkl_dev_blk_ops;
+
 /**
  * lkl_disk - host disk handle
  *
@@ -97,6 +102,7 @@ struct lkl_disk {
 		int fd;
 		void *handle;
 	};
+	struct lkl_dev_blk_ops *ops;
 };
 
 /**

tools/lkl/lib/virtio_blk.c

@@ -87,7 +87,10 @@ int lkl_disk_add(struct lkl_disk *disk)
 	dev->dev.config_data = &dev->config;
 	dev->dev.config_len = sizeof(dev->config);
 	dev->dev.ops = &blk_ops;
-	dev->ops = &lkl_dev_blk_ops;
+	if (disk->ops)
+		dev->ops = disk->ops;
+	else
+		dev->ops = &lkl_dev_blk_ops;
 	dev->disk = *disk;
 
 	ret = dev->ops->get_capacity(*disk, &capacity);

tools/lkl/tests/boot.c

@@ -349,6 +349,8 @@ int test_disk_add(char *str, int len)
 #endif
 		goto out_unlink;
 
+	disk.ops = NULL;
+
 	disk_id = lkl_disk_add(&disk);
 	if (disk_id < 0)
 		goto out_close;