Re: [Fwd: Getting IOCTL's into VFS File System Drivers]

Alan Cox (alan@lxorguk.ukuu.org.uk)
Thu, 11 Nov 1999 01:36:43 +0000 (GMT)


> these FS's). I basically need this for the utilities that create and
> config volumes and mirroring so I can query as to whether a file system
> is mounted from the tools, and prohibit users from blowing away volume

We always configure and create volumes in user space.

> segments, namespaces, etc. while a volume is mounted. There are also

Suppose they as root want to. Thats one of the things with Unix. We stop
dumb stuff and we stop users trashing the box, but we dont want to be
stopping users doing damage

> some question/answer stuff during boot from a Netware file system if
> NWFSCK (Netware volume repair utility) gets invoked due to mounting
> problems. I need to be able to pass back and forth, such as asking
> whether an imcomplete mirror group should be activated and failing
> mirrors dropped during system boot if FS errors are detected.

In the Unix world the tools would be user space. They open the drive and they
parse the mirror data etc. Then they work directly on /dev/hda or as
needed in order to fix the data if it needs fixing.

Suppose for example that the drives get shuffled. I know that but the kernel
doesn't. You will go and try and rebuild the mirror group without me being
able to stop it. if its in user space I can get out my custom editing toy
fix it and then fsck the disk.

Similarly in a bad situation I may want to forcibly mount the fs read only
and unrecovered to make a copy to tape before doing a risky recovery.

Why do you need to trigger this from the kernel side ?

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