fs: Provide information about non-block filesystems

The existing disk and partition code assumes a block device.

Sandbox provides access to host files and does not operate through a
block device. This is currently handled with special-case logic.

We want to add virtio-fs support, which is also not a block device. It
is not easy to have these two co-exist, so add a new type field to
struct disk_partition to indicate the type.

This is a work-around to deal with the fact that the type needs to be
set by blk_get_device_part_str() in such a way that it is visible to
fs_readdir()

There is a global fs_type in disk/part.c but this is not available in
the fs/ code.

Signed-off-by: Simon Glass <sjg@chromium.org>

disk/part.c

@@ -477,7 +477,8 @@ int blk_get_device_part_str(const char *ifname, const char *dev_part_str,
 	if (!strcmp(ifname, "hostfs")) {
 		strcpy((char *)info->type, BOOT_PART_TYPE);
 		strcpy((char *)info->name, "Host filesystem");
-
+		info->fs_type = IS_ENABLED(CONFIG_SANDBOX) ? FS_TYPE_SANDBOX :
+			FS_TYPE_SEMIHOSTING;
 		return 0;
 	}
 #endif