Alon Altman
Thu, 13 Sep 2007 03:39:58 -0700
Can it link back a loopmounted filesystem?
On 9/13/07, Amos Shapira <[EMAIL PROTECTED]> wrote:
> Hi (and happy new year).
>
> I've had this idea ever since someone asked about this situation on this
> forum a few months ago:
>
> Considering that you have a long running process writing stuff into a large
> file, and you accidentally delete that file.
> You can still access the file's content through /proc/<pid>/fd/<fd> and
> that's basically the suggestion he was given ("cp /proc... new file"),
> but the limitations of this solution are:
>
> 1. It will loose any changes made to the deleted file after the copy.
> 2. It creates another copy of the data (could be a problem if there isn't
> enough space on any partition).
>
> My solution (available in
> http://sourceforge.net/projects/fdlink) is to enable the
> user to link back the deleted file to a new name on the same filesystem as
> the deleted file.
>
> The solution involves as small kernel module and a simple program which
> calls ioctl(2) on the special device created by that module.
>
> The idea is that if someone finds themselves in that situation they should
> be able to install that module and use it without having to reboot the
> system (and thus loosing the whole point of it).
>
> I have a couple of enhancement that I'm waiting to find time to implement:
>
> 1. Update the symlink content under fd/<fd> to point to the new file name.
> 2. Implement this as a system call and offer this to be included in 2.6
>
> The module was tested under Debian 2.6.18 and later on x86_64.
>
> Any comments/suggestions/contributions are welcome.
>
> Cheers,
>
> --Amos
>
>
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