Resize 调整大小 

A mounted filesystem can be resized after creation, grown or shrunk. On a multi-device filesystem the space occupied on each device can be resized independently. Data that reside in the area that would be out of the new size are relocated to the remaining space below the limit, so this constrains the minimum size to which a filesystem can be shrunk.
挂载的文件系统在创建后可以调整大小，可以扩大或缩小。在多设备文件系统上，每个设备上占用的空间可以独立调整大小。位于新大小范围之外的数据将被重新定位到下限以下的剩余空间，因此这限制了文件系统可以缩小到的最小大小。

Growing a filesystem is quick as it only needs to take note of the available space, while shrinking a filesystem needs to relocate potentially lots of data and this is IO intense. It is possible to shrink a filesystem in smaller steps. See btrfs filesystem resize for more.
扩展文件系统很快，因为它只需要注意可用空间，而缩小文件系统需要重新定位大量数据，这会导致 IO 密集。可以分步缩小文件系统。更多信息请参阅 btrfs 文件系统调整大小。