包含大量目录的overlayfs

Question

假设我有任意数量的目录，用数字标记。

我还有目录merge。

我能做到

mount -t overlay -olowerdir=1:2:50 overlay merge

获取1、2和50在merge中的内容。

将更多目录“添加”到覆盖层的最佳方法是什么，比如，23、81和457，就好像我已经执行了命令一样

mount -t overlay -olowerdir=1:2:50:23:81:457 overlay merge

一开始？

如果我想“打开”某个目录(比如23 )，我可以在不卸载整个目录的情况下这样做吗？

概念上，我想你可以说我想要任意数量的目录在相同的“层次”的覆盖。

Answer 1

(我也有同样的问题。)我能找到的唯一信息是：

来自https://lkml.org/lkml/2014/11/10/129：

Maybe it wasn't clear, but the number of lower layers isn't limited by
FILESYSTEM_MAX_STACK_DEPTH, only by the max size of the mount option buffer in
the kernel (1 page, usually 4096bytes).  So you could have a hundred read-only
layers stacked in a single overlayfs mount.

As for changing the stacking while the overlayfs is mounted: currently this is
not supported, the layers specified at the mount time remain there until the
overlay is unmounted.  Currently there's no possibility to add or remove layers
in a dynamic way, and it is definitely more tricky to implement than the static 
configuration.

-- Miklos Szeredi Mon, 10 Nov 2014