Re: [PATCH v6 00/28] fs: fixes for serious clone/dedupe problems

Dave Chinner
2018-10-22T10:37:46Z

On Sun, Oct 21, 2018 at 09:15:03AM -0700, Darrick J. Wong wrote:
> Hi all,
>
> Dave, Eric, and I have been chasing a stale data exposure bug in the XFS
> reflink implementation, and tracked it down to reflink forgetting to do
> some of the file-extending activities that must happen for regular
> writes.
>
> We then started auditing the clone, dedupe, and copyfile code and
> realized that from a file contents perspective, clonerange isn't any
> different from a regular file write. Unfortunately, we also noticed
> that *unlike* a regular write, clonerange skips a ton of overflow
> checks, such as validating the ranges against s_maxbytes, MAX_NON_LFS,
> and RLIMIT_FSIZE. We also observed that cloning into a file did not
> strip security privileges (suid, capabilities) like a regular write
> would. I also noticed that xfs and ocfs2 need to dump the page cache
> before remapping blocks, not after.
>
> In fixing the range checking problems I also realized that both dedupe
> and copyfile tell userspace how much of the requested operation was
> acted upon. Since the range validation can shorten a clone request (or
> we can ENOSPC midway through), we might as well plumb the short
> operation reporting back through the VFS indirection code to userspace.
> I added a few more cleanups to the xfs code per reviewer suggestions.
>
> So, here's the whole giant pile of patches[1] that fix all the problems.
> This branch is against current upstream (4.19-rc8). The patch
> "generic: test reflink side effects" recently sent to fstests exercises
> the fixes in this series. Tests are in [2].

Ok, so now that all the patches (other than the ocfs2 bits) have been
reviewed, how do we want to merge this? I can take it through the
XFS tree given that there is a bit of XFS changes that needs to be
co-ordinated with it, or should it go through some other tree?

The other question I have is who reviews ocfs2 changes these days?
Do they get reviewed, or just shepherded in via akpm's tree?

Cheers,

Dave.
--
Dave Chinner
david@fromorbit.com