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

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Date:   Sun, 16 Sep 2018 04:02:52 +0000
From:   Wang Shilong <wshilong@....com>
To:     Theodore Ts'o <tytso@....edu>
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



> 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.


> 
> 				- Ted