linux-ext4 - Re: [PATCH v3 1/3] ext4: fix setattr project check upon fssetxattr ioctl

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Date:   Sun, 16 Sep 2018 08:20:34 -0400
From:   "Theodore Y. Ts'o" <tytso@....edu>
To:     Wang Shilong <wshilong@....com>
Cc:     Wang Shilong <wangshilong1991@...il.com>,
        "linux-ext4@...r.kernel.org" <linux-ext4@...r.kernel.org>,
        "linux-f2fs-devel@...ts.sourceforge.net" 
        <linux-f2fs-devel@...ts.sourceforge.net>,
        "dchinner@...hat.com" <dchinner@...hat.com>,
        "adilger@...ger.ca" <adilger@...ger.ca>
Subject: Re: [PATCH v3 1/3] ext4: fix setattr project check upon fssetxattr
 ioctl

On Sun, Sep 16, 2018 at 04:02:52AM +0000, Wang Shilong wrote:
> 
> 
> > 在 2018年9月16日，上午11:55，Theodore Y. Ts'o <tytso@....edu> 写道：
> > 
> > On Wed, Sep 12, 2018 at 08:57:16AM +0900, Wang Shilong wrote:
> >> diff --git a/fs/ext4/ioctl.c b/fs/ext4/ioctl.c
> >> index a7074115d6f6..f81102bd3203 100644
> >> --- a/fs/ext4/ioctl.c
> >> +++ b/fs/ext4/ioctl.c
> >> @@ -339,19 +339,14 @@ static int ext4_ioctl_setproject(struct file *filp, __u32 projid)
> >> 	if (projid_eq(kprojid, EXT4_I(inode)->i_projid))
> >> 		return 0;
> >> 
> >> -	err = mnt_want_write_file(filp);
> >> -	if (err)
> >> -		return err;
> >> -
> > 
> > A huge part of this patch is dropping the calls to
> > mnt_want_write_file() and mnt_drop_write_file().  What's the
> > justification for doing this?  The use of mnt_want_write_file() looks
> > necessary to me…
> 
> Hi Ted,
> 
>      mnt_want_write_file() and inode_lock is held before this function called now.
> Since both ioctl_set_flags and ext4_set_project() need call them.

I don't see any place in this patch where mnt_want_write_file() is
being called.  What am I missing?  And if there is a dependent patch
to this first patch in the patch series, please include it in this
patch series....  or least point it out after the --- list.

Thanks,

						- Ted