On Tue, Feb 26, 2008 at 09:16:25AM +0100, Willy Tarreau wrote:
> On Mon, Feb 25, 2008 at 09:36:12PM -1000, Glen Nakamura wrote:
> > Aloha,
> >
> > The "ext2_readdir() filp->f_pos fix" patch looks weird...
> > Perhaps the "filp->f_pos += le16_to_cpu(de->rec_len);" line should be
> > outside of the if statement like the indentation implies?
>
> good catch! At least it's what is done in 2.6.
Yes, that certainly looks like a bug.
> > As it is, filp->f_pos gets corrupted if de->inode is ever zero...
> > This could possibly explain why I had a few strange directory
> > entries until I checked the filesystem with:
> > e2fsck -D -F -f /dev/{ext2 partition}
> >
> > - glen
> >
> > Here is an updated (untested) patch:
>
> unfortunately, neither Dann nor me could reproduce the issue, so
> we'll wait for some victims^Wvolunteers to give it a try.
I'm now able to reliably reproduce it by creating/removing a chroot
(pbuilder create on a Debian system, though I'm sure a simpler test
exists). Correcting the le16_to_cpu placement as Glen described
fixes the issue for me.
> BTW, I notice that 2.6 also has one extra chunk that 2.4 does not
> have :
>
> if (unlikely(need_revalidate)) {
> + if (offset) {
> offset = ext2_validate_entry(kaddr, offset,
> chunk_mask);
> + filp->f_pos = (n<<PAGE_CACHE_SHIFT) + offset;
> + }
> + filp->f_version = inode->i_version;
> need_revalidate = 0;
> }
>
> I have no idea whether this part is needed, we'd better ask Theo or Al
> for some advices, as I'm not tempted by merging an uncertain patch when
> it comes to filesystems.
Looks like a test case may be available:
http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commitdiff;h=2d7f2ea9c989853310c7f6e8be52cc090cc8e66b
--
dann frazier
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