linux-ext4 - Re: [PATCH v5 16/16] f2fs: add fs-verity support

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Message-ID: <20190625175225.GC81914@gmail.com>
Date:   Tue, 25 Jun 2019 10:52:26 -0700
From:   Eric Biggers <ebiggers@...nel.org>
To:     Chao Yu <yuchao0@...wei.com>
Cc:     linux-fscrypt@...r.kernel.org, linux-ext4@...r.kernel.org,
        linux-f2fs-devel@...ts.sourceforge.net,
        linux-fsdevel@...r.kernel.org, linux-api@...r.kernel.org,
        linux-integrity@...r.kernel.org, Jaegeuk Kim <jaegeuk@...nel.org>,
        "Theodore Y . Ts'o" <tytso@....edu>,
        Victor Hsieh <victorhsieh@...gle.com>,
        Chandan Rajendra <chandan@...ux.vnet.ibm.com>,
        Dave Chinner <david@...morbit.com>,
        Christoph Hellwig <hch@....de>,
        "Darrick J . Wong" <darrick.wong@...cle.com>,
        Linus Torvalds <torvalds@...ux-foundation.org>
Subject: Re: [PATCH v5 16/16] f2fs: add fs-verity support

Hi Chao, thanks for the review.

On Tue, Jun 25, 2019 at 03:55:57PM +0800, Chao Yu wrote:
> Hi Eric,
> 
> On 2019/6/21 4:50, Eric Biggers wrote:
> > +static int f2fs_begin_enable_verity(struct file *filp)
> > +{
> > +	struct inode *inode = file_inode(filp);
> > +	int err;
> > +
> 
> I think we'd better add condition here (under inode lock) to disallow enabling
> verity on atomic/volatile inode, as we may fail to write merkle tree data due to
> atomic/volatile inode's special writeback method.
> 

Yes, I'll add the following:

	if (f2fs_is_atomic_file(inode) || f2fs_is_volatile_file(inode))
		return -EOPNOTSUPP;

> > +	err = f2fs_convert_inline_inode(inode);
> > +	if (err)
> > +		return err;
> > +
> > +	err = dquot_initialize(inode);
> > +	if (err)
> > +		return err;
> 
> We can get rid of dquot_initialize() here, since f2fs_file_open() ->
> dquot_file_open() should has initialized quota entry previously, right?

We still need it because dquot_file_open() only calls dquot_initialize() if the
file is being opened for writing.  But here the file descriptor is readonly.
I'll add a comment explaining this here and in the ext4 equivalent.

- Eric