On Mon, Sep 03, 2018 at 02:04:23PM +0300, Nikolay Borisov wrote:
> On 3.09.2018 13:14, Adam Borowski wrote:
> > - fd = open(fpath, O_RDWR);
> > + fd = open(fpath, defrag_ro);
>
> Looking at the kernel code I think this is in fact incorrect, because in
> ioctl.c we have:
>
> if (!(file->f_mode & FMODE_WRITE)) {
>
> ret = -EINVAL;
>
> goto out;
>
> }
>
> So it seems a hard requirement to have opened a file for RW when you
> want to defragment it.
Oif! I confused this with dedup, which does allow root to dedup RO even on
old kernels. Good catch.
--
⢀⣴⠾⠻⢶⣦⠀ What Would Jesus Do, MUD/MMORPG edition:
⣾⠁⢰⠒⠀⣿⡁ • multiplay with an admin char to benefit your mortal [Mt3:16-17]
⢿⡄⠘⠷⠚⠋⠀ • abuse item cloning bugs [Mt14:17-20, Mt15:34-37]
⠈⠳⣄⠀⠀⠀⠀ • use glitches to walk on water [Mt14:25-26]
