Re: [RFC PATCH] overlayfs: support more than one read-only layer

[Erez Zadok]

Indeed, Miklos, changing layers dynamically is VERY tricky.  Unionfs supports that, but a good amount of its code all over is dedicated to handling dynamic layer changes.  I advise you to avoid supporting this feature for a while, if ever: get a small, functional, working overlayfs first.

I personally never liked the idea of changing layers dynamically: itâs like asking a file system to remain consistent and detect all lower changes when someone goes and hand-edits disk blocks.  Too messy.  The pain of developing and supporting such a feature is much greater than the annoyance to users who have to unmount and remount back their layers to form a new structure.

Cheers,
Erez.

> On Nov 10, 2014, at 4:09 AM, Miklos Szeredi <miklos@xxxxxxxxxx> wrote:
> 
> 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.
> 
> Thanks,
> Miklos

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