Technical question about mount/remount ro/rw

[Fulgurance]

Hi guys, as some know, I am working on my package manager.

I decided to add a lock system that when it install a package, it unlock the /bin /sbin /lib and /libexec directories as rw, but when the installation is finished, it's remounted as ro.

So it work, but I am facing a big problem. When I do this test (so under virtual machine), it look like after a while, I mean after changing from RO to RW few times, I am facing big performance issues. The system become extremly slow (under the VM)
Is it normal ?
Is there any way to improve this ?

Basically when I unlock/lock, I run these commands:

[pingtoo]

Not able to tell in you code logic if mount/umount pair were performed or not.

So may be just check use 'mount' command to see if you have many many time mount same directories.

[Fulgurance]

I find a better way to do so.

I realized this method wasn't really what I am looking for, because it is not the purpose of rbind option.

Thank you for your help anyway

I will use chattr
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My actual project: https://github.com/Fulgurance/ISM

Ingenius Software Manager is a tool to build and manage a Linux system from scratch.
It will able to manage a linux installation just with a given path to the futur root path

[Hu]

I think chattr is a worse way. It does not work on all filesystems, and is persistent, so an untimely system halt may leave the directory in the wrong state. Further, it is not recursive.

A read-only mount is a good approach for what you said you want, but you need to do it properly. I would also use a private mount namespace for the read-write mount, so that nothing else has access during the window that your package manager is working on it.

[szatox]

Are you looking for union mount?
Overlayfs is in the main kernel, there's a good chance your system already has all the pieces and you can just use it. And since it keeps all changes in a separate directory, you can reset things with a simple rm -rf
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