Re: JFS resize=0 problem in 2.6.0

Elliott Bennett
2004-01-06T15:24:27Z

On Fri, Jan 02, 2004 at 11:33:03PM +0100, Christophe Saout wrote:
> Am So, den 28.12.2003 schrieb lkml@dhtns.com um 16:30:
>
> > Let me know if I'm missing the goal of the code here, but lines 261-273
> > of linux-2.6.0/fs/jfs/super.c are:
> >
> > case Opt_resize:
> > {
> > char *resize = args[0].from;
> > if (!resize || !*resize) { /* LINE 264 HERE */
> > *newLVSize = sb->s_bdev->bd_inode->i_size >>
> > sb->s_blocksize_bits;
> > if (*newLVSize == 0)
> > printk(KERN_ERR
> > "JFS: Cannot determine volume size\n");
> > } else
> > *newLVSize = simple_strtoull(resize, &resize, 0);
> > break;
> > }
> >
> > It seems to me that line 264 is attempting to test for the mount
> > paramater "resize=0", and when it comes across this, resize to the full
> > size of the volume. However, this doesn't work. I believe it should
> > test for the char '0' (*resize=='0'), not against literal zero.
>
> literal zero is the end of the string.
>
> So the code checks for resize= and not resize=0.
>
> I think your fix is wrong because it would also recognize resize=0123
> because it only tests the first character.
>
> - if (!resize || !*resize) {
> + if (!resize || !*resize || *resize=='0')
>
> It should probably be
>
> + if (!resize || !*resize || (*resize=='0' && !resize[1]))
>
> Or better: check the integer value that is returned by simple_strtoull.
>
> But did you test what resize= does?
>
>

Good catch! I'm embarrassed that I didn't see that.

As for "resize=", it seems to fail. Probably because it doesn't match
the "resize=%u" pattern:

root@tesla:~# mount -o remount,resize= /mnt
mount: /mnt not mounted already, or bad option

Someone posted a patch the other day that supposedly handles both
"resize=0" and "resize" alone..I believe by simply adding it to the
pattern list.

-Elliott