linux-kernel - Re: Question: Why is there no notification when a file is opened using filp

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Date:   Tue, 8 Sep 2020 20:53:07 +0800
From:   Xiaoming Ni <nixiaoming@...wei.com>
To:     Amir Goldstein <amir73il@...il.com>
CC:     Jan Kara <jack@...e.cz>,
        linux-fsdevel <linux-fsdevel@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        <wangle6@...wei.com>
Subject: Re: Question: Why is there no notification when a file is opened
 using filp_open()?

On 2020/9/8 18:06, Amir Goldstein wrote:
> On Tue, Sep 8, 2020 at 11:02 AM Xiaoming Ni <nixiaoming@...wei.com> wrote:
>>
>> The file opening action on the system may be from user-mode sys_open()
>> or kernel-mode filp_open().
>> Currently, fsnotify_open() is invoked in do_sys_openat2().
>> But filp_open() is not notified. Why? Is this an omission?
>>
>> Do we need to call fsnotify_open() in filp_open() or  do_filp_open() to
>> ensure that both user-mode and kernel-mode file opening operations can
>> be notified?
>>
> 
> Do you have a specific use case of kernel filp_open() in mind?
> 

For example, in fs/coredump.c, do_coredump() calls filp_open() to 
generate core files.
In this scenario, the fsnotify_open() notification is missing.

Thanks
Xiaoming Ni