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Date:   Sun, 7 Feb 2021 00:01:45 -0800
From:   Eric Biggers <ebiggers@kernel.org>
To:     Chao Yu <yuchao0@huawei.com>
Cc:     linux-fscrypt@vger.kernel.org, Theodore Ts'o <tytso@mit.edu>,
        linux-api@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net,
        linux-fsdevel@vger.kernel.org, Jaegeuk Kim <jaegeuk@kernel.org>,
        linux-ext4@vger.kernel.org, Victor Hsieh <victorhsieh@google.com>
Subject: Re: [PATCH 3/6] fs-verity: add FS_IOC_READ_VERITY_METADATA ioctl
Message-ID: <YB+ead3SvsQy5ULH@sol.localdomain>
References: <20210115181819.34732-1-ebiggers@kernel.org>
 <20210115181819.34732-4-ebiggers@kernel.org>
 <107cf2f2-a6fe-57c2-d17d-57679d7c612d@huawei.com>
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On Sun, Feb 07, 2021 at 03:46:43PM +0800, Chao Yu wrote:
> Hi Eric,
> 
> On 2021/1/16 2:18, Eric Biggers wrote:
> > +static int f2fs_ioc_read_verity_metadata(struct file *filp, unsigned long arg)
> > +{
> > +	if (!f2fs_sb_has_verity(F2FS_I_SB(file_inode(filp))))
> > +		return -EOPNOTSUPP;
> 
> One case is after we update kernel image, f2fs module may no longer support
> compress algorithm which current file was compressed with, to avoid triggering
> IO with empty compress engine (struct f2fs_compress_ops pointer):
> 
> It needs to add f2fs_is_compress_backend_ready() check condition here?
> 
> Thanks,
> 
> > +
> > +	return fsverity_ioctl_read_metadata(filp, (const void __user *)arg);
> > +}

In that case it wouldn't have been possible to open the file, because
f2fs_file_open() checks for it.  So it's not necessary to repeat the same check
in every operation on the file descriptor.

- Eric