[PATCH] quotactl.2: Remove kernel version for Q_XQUOTARM ioctl

[PATCH] quotactl.2: Remove kernel version for Q_XQUOTARM ioctl

[Yang Xu]

This patch[1] is designed to fix bug for Q_XQUOTARM ioctl not for introduced.
So remove it.

[1]https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=9da93f9b7c

Signed-off-by: Yang Xu <xuyang2018.jy@fujitsu.com>
---
 man2/quotactl.2 | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/man2/quotactl.2 b/man2/quotactl.2
index d22d8c584..46f77a8b1 100644
--- a/man2/quotactl.2
+++ b/man2/quotactl.2
@@ -651,8 +651,7 @@ The
 .I id
 argument is ignored.
 .TP
-.B Q_XQUOTARM " (since Linux 3.16)"
-.\" 9da93f9b7cdf8ab28da6b364cdc1fafc8670b4dc
+.B Q_XQUOTARM
 Free the disk space taken by disk quotas.
 The
 .I addr
-- 
2.23.0

Re: [PATCH] quotactl.2: Remove kernel version for Q_XQUOTARM ioctl

[xuyang2018.jy]

Hi Alejandro, Michael

Ping!

Best Regards
Yang Xu
> This patch[1] is designed to fix bug for Q_XQUOTARM ioctl not for introduced.
> So remove it.
> 
> [1]https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=9da93f9b7c
> 
> Signed-off-by: Yang Xu<xuyang2018.jy@fujitsu.com>
> ---
>   man2/quotactl.2 | 3 +--
>   1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/man2/quotactl.2 b/man2/quotactl.2
> index d22d8c584..46f77a8b1 100644
> --- a/man2/quotactl.2
> +++ b/man2/quotactl.2
> @@ -651,8 +651,7 @@ The
>   .I id
>   argument is ignored.
>   .TP
> -.B Q_XQUOTARM " (since Linux 3.16)"
> -.\" 9da93f9b7cdf8ab28da6b364cdc1fafc8670b4dc
> +.B Q_XQUOTARM
>   Free the disk space taken by disk quotas.
>   The
>   .I addr

Re: [PATCH] quotactl.2: Remove kernel version for Q_XQUOTARM ioctl

[xuyang2018.jy]

Hi Alejandro

You merged another quotactl patch, but I guess you missed this.


Best Regards
Yang Xu
> Hi Alejandro, Michael
> 
> Ping!
> 
> Best Regards
> Yang Xu
>> This patch[1] is designed to fix bug for Q_XQUOTARM ioctl not for introduced.
>> So remove it.
>>
>> [1]https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=9da93f9b7c
>>
>> Signed-off-by: Yang Xu<xuyang2018.jy@fujitsu.com>
>> ---
>>    man2/quotactl.2 | 3 +--
>>    1 file changed, 1 insertion(+), 2 deletions(-)
>>
>> diff --git a/man2/quotactl.2 b/man2/quotactl.2
>> index d22d8c584..46f77a8b1 100644
>> --- a/man2/quotactl.2
>> +++ b/man2/quotactl.2
>> @@ -651,8 +651,7 @@ The
>>    .I id
>>    argument is ignored.
>>    .TP
>> -.B Q_XQUOTARM " (since Linux 3.16)"
>> -.\" 9da93f9b7cdf8ab28da6b364cdc1fafc8670b4dc
>> +.B Q_XQUOTARM
>>    Free the disk space taken by disk quotas.
>>    The
>>    .I addr

Re: [PATCH] quotactl.2: Remove kernel version for Q_XQUOTARM ioctl

[xuyang2018.jy]

[Fix Alejandro mail address ]
> Hi Alejandro
> 
> You merged another quotactl patch, but I guess you missed this.
> 
> 
> Best Regards
> Yang Xu
>> Hi Alejandro, Michael
>>
>> Ping!
>>
>> Best Regards
>> Yang Xu
>>> This patch[1] is designed to fix bug for Q_XQUOTARM ioctl not for introduced.
>>> So remove it.
>>>
>>> [1]https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=9da93f9b7c
>>>
>>> Signed-off-by: Yang Xu<xuyang2018.jy@fujitsu.com>
>>> ---
>>>     man2/quotactl.2 | 3 +--
>>>     1 file changed, 1 insertion(+), 2 deletions(-)
>>>
>>> diff --git a/man2/quotactl.2 b/man2/quotactl.2
>>> index d22d8c584..46f77a8b1 100644
>>> --- a/man2/quotactl.2
>>> +++ b/man2/quotactl.2
>>> @@ -651,8 +651,7 @@ The
>>>     .I id
>>>     argument is ignored.
>>>     .TP
>>> -.B Q_XQUOTARM " (since Linux 3.16)"
>>> -.\" 9da93f9b7cdf8ab28da6b364cdc1fafc8670b4dc
>>> +.B Q_XQUOTARM
>>>     Free the disk space taken by disk quotas.
>>>     The
>>>     .I addr

Re: [PATCH] quotactl.2: Remove kernel version for Q_XQUOTARM ioctl

[Alejandro Colomar (man-pages)]

[CC += Jan]

Hi Yang,

On 11/3/21 10:29, xuyang2018.jy@fujitsu.com wrote:
> [Fix Alejandro mail address ]
>> Hi Alejandro
>>
>> You merged another quotactl patch, but I guess you missed this.

Thanks!

>>
>>
>> Best Regards
>> Yang Xu
>>> Hi Alejandro, Michael
>>>
>>> Ping!
>>>
>>> Best Regards
>>> Yang Xu
>>>> This patch[1] is designed to fix bug for Q_XQUOTARM ioctl not for introduced.
>>>> So remove it.
>>>>
>>>> [1]https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=9da93f9b7c
>>>>
>>>> Signed-off-by: Yang Xu<xuyang2018.jy@fujitsu.com>
>>>> ---
>>>>      man2/quotactl.2 | 3 +--
>>>>      1 file changed, 1 insertion(+), 2 deletions(-)
>>>>
>>>> diff --git a/man2/quotactl.2 b/man2/quotactl.2
>>>> index d22d8c584..46f77a8b1 100644
>>>> --- a/man2/quotactl.2
>>>> +++ b/man2/quotactl.2
>>>> @@ -651,8 +651,7 @@ The
>>>>      .I id
>>>>      argument is ignored.
>>>>      .TP
>>>> -.B Q_XQUOTARM " (since Linux 3.16)"
>>>> -.\" 9da93f9b7cdf8ab28da6b364cdc1fafc8670b4dc

Okay.  Since you added that line (man-pages commit ae848b1d80), I'm fine 
removing it.  Was it a mistake?  The commit message of that commit is a 
bit unrelated to Q_XQUOTARM, isn't it?

Maybe a better fix would be to replace the kernel version and the commit 
hash when it was really added?

I'll wait for your answer before applying the patch.

Thanks,

Alex

>>>> +.B Q_XQUOTARM
>>>>      Free the disk space taken by disk quotas.
>>>>      The
>>>>      .I addr


-- 
Alejandro Colomar
Linux man-pages comaintainer; https://www.kernel.org/doc/man-pages/
http://www.alejandro-colomar.es/

Re: [PATCH] quotactl.2: Remove kernel version for Q_XQUOTARM ioctl

[xuyang2018.jy]

Hi  Alejandro
> [CC += Jan]
>
> Hi Yang,
>
> On 11/3/21 10:29, xuyang2018.jy@fujitsu.com wrote:
>> [Fix Alejandro mail address ]
>>> Hi Alejandro
>>>
>>> You merged another quotactl patch, but I guess you missed this.
>
> Thanks!
>
>>>
>>>
>>> Best Regards
>>> Yang Xu
>>>> Hi Alejandro, Michael
>>>>
>>>> Ping!
>>>>
>>>> Best Regards
>>>> Yang Xu
>>>>> This patch[1] is designed to fix bug for Q_XQUOTARM ioctl not for
>>>>> introduced.
>>>>> So remove it.
>>>>>
>>>>> [1]https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=9da93f9b7c
>>>>>
>>>>>
>>>>> Signed-off-by: Yang Xu<xuyang2018.jy@fujitsu.com>
>>>>> ---
>>>>> man2/quotactl.2 | 3 +--
>>>>> 1 file changed, 1 insertion(+), 2 deletions(-)
>>>>>
>>>>> diff --git a/man2/quotactl.2 b/man2/quotactl.2
>>>>> index d22d8c584..46f77a8b1 100644
>>>>> --- a/man2/quotactl.2
>>>>> +++ b/man2/quotactl.2
>>>>> @@ -651,8 +651,7 @@ The
>>>>> .I id
>>>>> argument is ignored.
>>>>> .TP
>>>>> -.B Q_XQUOTARM " (since Linux 3.16)"
>>>>> -.\" 9da93f9b7cdf8ab28da6b364cdc1fafc8670b4dc
>
> Okay. Since you added that line (man-pages commit ae848b1d80), I'm fine
> removing it. Was it a mistake? The commit message of that commit is a
> bit unrelated to Q_XQUOTARM, isn't it?
Yes.
>
> Maybe a better fix would be to replace the kernel version and the commit
> hash when it was really added?
Yes, but I can't find this commit hash and it seems been supported since 
long time ago.

Best Regards
Yang Xu
>
> I'll wait for your answer before applying the patch.
>
> Thanks,
>
> Alex
>
>>>>> +.B Q_XQUOTARM
>>>>> Free the disk space taken by disk quotas.
>>>>> The
>>>>> .I addr
>
>

Re: [PATCH] quotactl.2: Remove kernel version for Q_XQUOTARM ioctl

[Eugene Syromyatnikov]

On Thu, Nov 4, 2021 at 2:05 AM xuyang2018.jy@fujitsu.com
<xuyang2018.jy@fujitsu.com> wrote:
> > Maybe a better fix would be to replace the kernel version and the commit
> > hash when it was really added?
> Yes, but I can't find this commit hash and it seems been supported since
> long time ago.

Q_XQUOTARM was added as part of the initial quotactl(2) implementation
in commit v2.5.17~10^2~6[1].

[1] https://git.kernel.org/pub/scm/linux/kernel/git/tglx/history.git/commit/?id=b5abbc1f844d101615d6d2c5abac8a692f028d01

-- 
Eugene Syromyatnikov
mailto:evgsyr@gmail.com
xmpp:esyr@jabber.{ru|org}

Re: [PATCH] quotactl.2: Remove kernel version for Q_XQUOTARM ioctl

[Jan Kara]

On Thu 04-11-21 00:58:02, xuyang2018.jy@fujitsu.com wrote:
> >>>>> This patch[1] is designed to fix bug for Q_XQUOTARM ioctl not for
> >>>>> introduced.
> >>>>> So remove it.
> >>>>>
> >>>>> [1]https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=9da93f9b7c
> >>>>>
> >>>>>
> >>>>> Signed-off-by: Yang Xu<xuyang2018.jy@fujitsu.com>
> >>>>> ---
> >>>>> man2/quotactl.2 | 3 +--
> >>>>> 1 file changed, 1 insertion(+), 2 deletions(-)
> >>>>>
> >>>>> diff --git a/man2/quotactl.2 b/man2/quotactl.2
> >>>>> index d22d8c584..46f77a8b1 100644
> >>>>> --- a/man2/quotactl.2
> >>>>> +++ b/man2/quotactl.2
> >>>>> @@ -651,8 +651,7 @@ The
> >>>>> .I id
> >>>>> argument is ignored.
> >>>>> .TP
> >>>>> -.B Q_XQUOTARM " (since Linux 3.16)"
> >>>>> -.\" 9da93f9b7cdf8ab28da6b364cdc1fafc8670b4dc
> >
> > Okay. Since you added that line (man-pages commit ae848b1d80), I'm fine
> > removing it. Was it a mistake? The commit message of that commit is a
> > bit unrelated to Q_XQUOTARM, isn't it?
> Yes.

Well, that commit fixed Q_XQUOTARM quotactl. Previously it was supported
but it was buggy and not actually doing the desired functionality in some
cases. So the description kind of make sense but it is not quite accurate -
maybe we should just move the note to NOTES section?

> > Maybe a better fix would be to replace the kernel version and the commit
> > hash when it was really added?
> Yes, but I can't find this commit hash and it seems been supported since 
> long time ago.

Yeah, AFAIK Q_XQUOTARM is there in principle since XFS was introduced in
the linux kernel so around 2001. No point of mentioning that in the manpage
IMO.

								Honza
-- 
Jan Kara <jack@suse.com>
SUSE Labs, CR

Re: [PATCH] quotactl.2: Remove kernel version for Q_XQUOTARM ioctl

[Eugene Syromyatnikov]

On Thu, Nov 4, 2021 at 11:43 AM Eugene Syromyatnikov <evgsyr@gmail.com> wrote:
> Q_XQUOTARM was added as part of the initial quotactl(2) implementation
> in commit v2.5.17~10^2~6[1].

s/initial/generic/


-- 
Eugene Syromyatnikov
mailto:evgsyr@gmail.com
xmpp:esyr@jabber.{ru|org}

Re: [PATCH] quotactl.2: Remove kernel version for Q_XQUOTARM ioctl

[Alejandro Colomar (man-pages)]

Hi Jan and Yang,

On 11/4/21 11:53, Jan Kara wrote:
> On Thu 04-11-21 00:58:02, xuyang2018.jy@fujitsu.com wrote:
>>>>>>> This patch[1] is designed to fix bug for Q_XQUOTARM ioctl not for
>>>>>>> introduced.
>>>>>>> So remove it.
>>>>>>>
>>>>>>> [1]https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=9da93f9b7c
>>>>>>>
>>>>>>>
>>>>>>> Signed-off-by: Yang Xu<xuyang2018.jy@fujitsu.com>
>>>>>>> ---
>>>>>>> man2/quotactl.2 | 3 +--
>>>>>>> 1 file changed, 1 insertion(+), 2 deletions(-)
>>>>>>>
>>>>>>> diff --git a/man2/quotactl.2 b/man2/quotactl.2
>>>>>>> index d22d8c584..46f77a8b1 100644
>>>>>>> --- a/man2/quotactl.2
>>>>>>> +++ b/man2/quotactl.2
>>>>>>> @@ -651,8 +651,7 @@ The
>>>>>>> .I id
>>>>>>> argument is ignored.
>>>>>>> .TP
>>>>>>> -.B Q_XQUOTARM " (since Linux 3.16)"
>>>>>>> -.\" 9da93f9b7cdf8ab28da6b364cdc1fafc8670b4dc

I applied the patch.

>>>
>>> Okay. Since you added that line (man-pages commit ae848b1d80), I'm fine
>>> removing it. Was it a mistake? The commit message of that commit is a
>>> bit unrelated to Q_XQUOTARM, isn't it?
>> Yes.
> 
> Well, that commit fixed Q_XQUOTARM quotactl. Previously it was supported
> but it was buggy and not actually doing the desired functionality in some
> cases. So the description kind of make sense but it is not quite accurate -
> maybe we should just move the note to NOTES section?

I think we better add a BUGS section.  Don't you?
Unless you think it isn't important enough.  How likely is it that 
Q_XQUOTARM was used in kernels before 3.16 and a BUGS section will help 
fix the bug?  And how likely is it that someone will use it in the 
future for kernels before 3.16?  How important/dangerous was the bug?

Maybe add something simpler such as "(buggy until Linux 3.16)" so that 
no one uses it in older kernels but doesn't use as much space as a new 
BUGS section?

> 
>>> Maybe a better fix would be to replace the kernel version and the commit
>>> hash when it was really added?
>> Yes, but I can't find this commit hash and it seems been supported since
>> long time ago.
> 
> Yeah, AFAIK Q_XQUOTARM is there in principle since XFS was introduced in
> the linux kernel so around 2001. No point of mentioning that in the manpage
> IMO.
> 
> 								Honza
> 

Thanks,

Alex


-- 
Alejandro Colomar
Linux man-pages comaintainer; https://www.kernel.org/doc/man-pages/
http://www.alejandro-colomar.es/

Re: [PATCH] quotactl.2: Remove kernel version for Q_XQUOTARM ioctl

[xuyang2018.jy]

on 2021/11/5 4:10, Alejandro Colomar (man-pages) wrote:
> Hi Jan and Yang,
>
> On 11/4/21 11:53, Jan Kara wrote:
>> On Thu 04-11-21 00:58:02, xuyang2018.jy@fujitsu.com wrote:
>>>>>>>> This patch[1] is designed to fix bug for Q_XQUOTARM ioctl not for
>>>>>>>> introduced.
>>>>>>>> So remove it.
>>>>>>>>
>>>>>>>> [1]https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=9da93f9b7c
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>> Signed-off-by: Yang Xu<xuyang2018.jy@fujitsu.com>
>>>>>>>> ---
>>>>>>>> man2/quotactl.2 | 3 +--
>>>>>>>> 1 file changed, 1 insertion(+), 2 deletions(-)
>>>>>>>>
>>>>>>>> diff --git a/man2/quotactl.2 b/man2/quotactl.2
>>>>>>>> index d22d8c584..46f77a8b1 100644
>>>>>>>> --- a/man2/quotactl.2
>>>>>>>> +++ b/man2/quotactl.2
>>>>>>>> @@ -651,8 +651,7 @@ The
>>>>>>>> .I id
>>>>>>>> argument is ignored.
>>>>>>>> .TP
>>>>>>>> -.B Q_XQUOTARM " (since Linux 3.16)"
>>>>>>>> -.\" 9da93f9b7cdf8ab28da6b364cdc1fafc8670b4dc
>
> I applied the patch.

Thanks.

>>>>
>>>> Okay. Since you added that line (man-pages commit ae848b1d80), I'm fine
>>>> removing it. Was it a mistake? The commit message of that commit is a
>>>> bit unrelated to Q_XQUOTARM, isn't it?
>>> Yes.
>>
>> Well, that commit fixed Q_XQUOTARM quotactl. Previously it was supported
>> but it was buggy and not actually doing the desired functionality in some
>> cases. So the description kind of make sense but it is not quite
>> accurate -
>> maybe we should just move the note to NOTES section?
>
> I think we better add a BUGS section. Don't you?
> Unless you think it isn't important enough. How likely is it that
> Q_XQUOTARM was used in kernels before 3.16 and a BUGS section will help
> fix the bug? And how likely is it that someone will use it in the future
> for kernels before 3.16? How important/dangerous was the bug?
@Jan
I doubt this ioctl whether be used by any application.

ps:I also increase ltp quotactl coverage to cover quotactl_fd syscall. I 
would appreciate it if you could review my ltp quotactl/quotactl_fd patchset
https://patchwork.ozlabs.org/project/ltp/list/?series=269166


>
> Maybe add something simpler such as "(buggy until Linux 3.16)" so that
> no one uses it in older kernels but doesn't use as much space as a new
> BUGS section?
@Alejandro
If this ioctl doesn't be used by many application(IMO,it is rare to be 
used ),  using "(buggy until Linux 3.16)" is better.

Best Regards
Yang Xu
>
>>
>>>> Maybe a better fix would be to replace the kernel version and the
>>>> commit
>>>> hash when it was really added?
>>> Yes, but I can't find this commit hash and it seems been supported since
>>> long time ago.
>>
>> Yeah, AFAIK Q_XQUOTARM is there in principle since XFS was introduced in
>> the linux kernel so around 2001. No point of mentioning that in the
>> manpage
>> IMO.
>>
>> Honza
>>
>
> Thanks,
>
> Alex
>
>

Re: [PATCH] quotactl.2: Remove kernel version for Q_XQUOTARM ioctl

[Jan Kara]

On Thu 04-11-21 21:10:12, Alejandro Colomar (man-pages) wrote:
> On 11/4/21 11:53, Jan Kara wrote:
> > On Thu 04-11-21 00:58:02, xuyang2018.jy@fujitsu.com wrote:
> > > > > > > > This patch[1] is designed to fix bug for Q_XQUOTARM ioctl not for
> > > > > > > > introduced.
> > > > > > > > So remove it.
> > > > > > > > 
> > > > > > > > [1]https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=9da93f9b7c
> > > > > > > > 
> > > > > > > > 
> > > > > > > > Signed-off-by: Yang Xu<xuyang2018.jy@fujitsu.com>
> > > > > > > > ---
> > > > > > > > man2/quotactl.2 | 3 +--
> > > > > > > > 1 file changed, 1 insertion(+), 2 deletions(-)
> > > > > > > > 
> > > > > > > > diff --git a/man2/quotactl.2 b/man2/quotactl.2
> > > > > > > > index d22d8c584..46f77a8b1 100644
> > > > > > > > --- a/man2/quotactl.2
> > > > > > > > +++ b/man2/quotactl.2
> > > > > > > > @@ -651,8 +651,7 @@ The
> > > > > > > > .I id
> > > > > > > > argument is ignored.
> > > > > > > > .TP
> > > > > > > > -.B Q_XQUOTARM " (since Linux 3.16)"
> > > > > > > > -.\" 9da93f9b7cdf8ab28da6b364cdc1fafc8670b4dc
> 
> I applied the patch.
> 
> > > > 
> > > > Okay. Since you added that line (man-pages commit ae848b1d80), I'm fine
> > > > removing it. Was it a mistake? The commit message of that commit is a
> > > > bit unrelated to Q_XQUOTARM, isn't it?
> > > Yes.
> > 
> > Well, that commit fixed Q_XQUOTARM quotactl. Previously it was supported
> > but it was buggy and not actually doing the desired functionality in some
> > cases. So the description kind of make sense but it is not quite accurate -
> > maybe we should just move the note to NOTES section?
> 
> I think we better add a BUGS section.  Don't you?
> Unless you think it isn't important enough.  How likely is it that
> Q_XQUOTARM was used in kernels before 3.16 and a BUGS section will help fix
> the bug?  And how likely is it that someone will use it in the future for
> kernels before 3.16?  How important/dangerous was the bug?
> 
> Maybe add something simpler such as "(buggy until Linux 3.16)" so that no
> one uses it in older kernels but doesn't use as much space as a new BUGS
> section?

Yeah, "(buggy until Linux 3.16)" sounds good to me.

								Honza
-- 
Jan Kara <jack@suse.com>
SUSE Labs, CR

Re: [PATCH] quotactl.2: Remove kernel version for Q_XQUOTARM ioctl

[Jan Kara]

On Fri 05-11-21 03:05:44, xuyang2018.jy@fujitsu.com wrote:
> ps:I also increase ltp quotactl coverage to cover quotactl_fd syscall. I 
> would appreciate it if you could review my ltp quotactl/quotactl_fd patchset
> https://patchwork.ozlabs.org/project/ltp/list/?series=269166

From a quick look the patches look fine. Just one thing I've noticed - you
seem to open "mntpoint/testfile" so that you have 'fd' to pass to
quotactl_fd(). Why don't you just open "mntpoint" directly?

								Honza
-- 
Jan Kara <jack@suse.com>
SUSE Labs, CR

Re: [PATCH] quotactl.2: Remove kernel version for Q_XQUOTARM ioctl

[xuyang2018.jy]

on 2021/11/5 19:34, Jan Kara wrote:
> On Fri 05-11-21 03:05:44, xuyang2018.jy@fujitsu.com wrote:
>> ps:I also increase ltp quotactl coverage to cover quotactl_fd syscall. I
>> would appreciate it if you could review my ltp quotactl/quotactl_fd patchset
>> https://patchwork.ozlabs.org/project/ltp/list/?series=269166
>
>  From a quick look the patches look fine. Just one thing I've noticed - you
> seem to open "mntpoint/testfile" so that you have 'fd' to pass to
> quotactl_fd(). Why don't you just open "mntpoint" directly?
Oh, yes.

At the beginning, I try it but open fails with EISDIR because I use RW 
mode for the file.

mnt_want_write(f.file->f_path.mnt) just need we can write something into 
superblock instead of a rw file. So I can use read-only fd directly.

Will use mntpoint directly.

Thanks.
>
> 								Honza