[PATCH] f2fs: fix wrong sum_page pointer in f2fs_gc

[PATCH] f2fs: fix wrong sum_page pointer in f2fs_gc

[Jaegeuk Kim]

This patch fixes using a wrong pointer for sum_page in f2fs_gc.

Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
---
 fs/f2fs/gc.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c
index e48142f..9c18917 100644
--- a/fs/f2fs/gc.c
+++ b/fs/f2fs/gc.c
@@ -854,16 +854,16 @@ static int do_garbage_collect(struct f2fs_sb_info *sbi,
 
 	for (segno = start_segno; segno < end_segno; segno++) {
 
-		if (get_valid_blocks(sbi, segno, 1) == 0 ||
-					unlikely(f2fs_cp_error(sbi)))
-			goto next;
-
 		/* find segment summary of victim */
 		sum_page = find_get_page(META_MAPPING(sbi),
 					GET_SUM_BLOCK(sbi, segno));
-		f2fs_bug_on(sbi, !PageUptodate(sum_page));
 		f2fs_put_page(sum_page, 0);
 
+		if (get_valid_blocks(sbi, segno, 1) == 0 ||
+				!PageUptodate(sum_page) ||
+				unlikely(f2fs_cp_error(sbi)))
+			goto next;
+
 		sum = page_address(sum_page);
 		f2fs_bug_on(sbi, type != GET_SUM_TYPE((&sum->footer)));
 
-- 
2.8.3


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Re: [PATCH] f2fs: fix wrong sum_page pointer in f2fs_gc

[Chao Yu]

Hi Jaegeuk,

On 2016/10/13 7:23, Jaegeuk Kim wrote:
> This patch fixes using a wrong pointer for sum_page in f2fs_gc.
> 
> Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
> ---
>  fs/f2fs/gc.c | 10 +++++-----
>  1 file changed, 5 insertions(+), 5 deletions(-)
> 
> diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c
> index e48142f..9c18917 100644
> --- a/fs/f2fs/gc.c
> +++ b/fs/f2fs/gc.c
> @@ -854,16 +854,16 @@ static int do_garbage_collect(struct f2fs_sb_info *sbi,
>  
>  	for (segno = start_segno; segno < end_segno; segno++) {
>  
> -		if (get_valid_blocks(sbi, segno, 1) == 0 ||
> -					unlikely(f2fs_cp_error(sbi)))
> -			goto next;
> -
>  		/* find segment summary of victim */
>  		sum_page = find_get_page(META_MAPPING(sbi),
>  					GET_SUM_BLOCK(sbi, segno));
> -		f2fs_bug_on(sbi, !PageUptodate(sum_page));
>  		f2fs_put_page(sum_page, 0);
>  
> +		if (get_valid_blocks(sbi, segno, 1) == 0 ||
> +				!PageUptodate(sum_page) ||

Why uptodate flag of summary page can be cleared? someone truncates it?

Thanks,

> +				unlikely(f2fs_cp_error(sbi)))
> +			goto next;
> +
>  		sum = page_address(sum_page);
>  		f2fs_bug_on(sbi, type != GET_SUM_TYPE((&sum->footer)));
>  
> 


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Re: [PATCH] f2fs: fix wrong sum_page pointer in f2fs_gc

[Jaegeuk Kim]

On Thu, Oct 13, 2016 at 06:33:19PM +0800, Chao Yu wrote:
> Hi Jaegeuk,
> 
> On 2016/10/13 7:23, Jaegeuk Kim wrote:
> > This patch fixes using a wrong pointer for sum_page in f2fs_gc.
> > 
> > Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
> > ---
> >  fs/f2fs/gc.c | 10 +++++-----
> >  1 file changed, 5 insertions(+), 5 deletions(-)
> > 
> > diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c
> > index e48142f..9c18917 100644
> > --- a/fs/f2fs/gc.c
> > +++ b/fs/f2fs/gc.c
> > @@ -854,16 +854,16 @@ static int do_garbage_collect(struct f2fs_sb_info *sbi,
> >  
> >  	for (segno = start_segno; segno < end_segno; segno++) {
> >  
> > -		if (get_valid_blocks(sbi, segno, 1) == 0 ||
> > -					unlikely(f2fs_cp_error(sbi)))
> > -			goto next;
> > -
> >  		/* find segment summary of victim */
> >  		sum_page = find_get_page(META_MAPPING(sbi),
> >  					GET_SUM_BLOCK(sbi, segno));
> > -		f2fs_bug_on(sbi, !PageUptodate(sum_page));
> >  		f2fs_put_page(sum_page, 0);
> >  
> > +		if (get_valid_blocks(sbi, segno, 1) == 0 ||
> > +				!PageUptodate(sum_page) ||
> 
> Why uptodate flag of summary page can be cleared? someone truncates it?

Well, it looks like no problem to remove this, since it will hit
f2fs_cp_error(). I just intended to handle the above f2fs_bug_on here.

I found you added the above bug_on, but it's not a big deal to remain tho. :)

718e53fa: f2fs: enhance foreground GC

Thanks,

> 
> Thanks,
> 
> > +				unlikely(f2fs_cp_error(sbi)))
> > +			goto next;
> > +
> >  		sum = page_address(sum_page);
> >  		f2fs_bug_on(sbi, type != GET_SUM_TYPE((&sum->footer)));
> >  
> > 

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Re: [PATCH] f2fs: fix wrong sum_page pointer in f2fs_gc

[Chao Yu]

On 2016/10/14 1:14, Jaegeuk Kim wrote:
> On Thu, Oct 13, 2016 at 06:33:19PM +0800, Chao Yu wrote:
>> Hi Jaegeuk,
>>
>> On 2016/10/13 7:23, Jaegeuk Kim wrote:
>>> This patch fixes using a wrong pointer for sum_page in f2fs_gc.
>>>
>>> Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
>>> ---
>>>  fs/f2fs/gc.c | 10 +++++-----
>>>  1 file changed, 5 insertions(+), 5 deletions(-)
>>>
>>> diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c
>>> index e48142f..9c18917 100644
>>> --- a/fs/f2fs/gc.c
>>> +++ b/fs/f2fs/gc.c
>>> @@ -854,16 +854,16 @@ static int do_garbage_collect(struct f2fs_sb_info *sbi,
>>>  
>>>  	for (segno = start_segno; segno < end_segno; segno++) {
>>>  
>>> -		if (get_valid_blocks(sbi, segno, 1) == 0 ||
>>> -					unlikely(f2fs_cp_error(sbi)))
>>> -			goto next;
>>> -
>>>  		/* find segment summary of victim */
>>>  		sum_page = find_get_page(META_MAPPING(sbi),
>>>  					GET_SUM_BLOCK(sbi, segno));
>>> -		f2fs_bug_on(sbi, !PageUptodate(sum_page));
>>>  		f2fs_put_page(sum_page, 0);
>>>  
>>> +		if (get_valid_blocks(sbi, segno, 1) == 0 ||
>>> +				!PageUptodate(sum_page) ||
>>
>> Why uptodate flag of summary page can be cleared? someone truncates it?
> 
> Well, it looks like no problem to remove this, since it will hit
> f2fs_cp_error(). I just intended to handle the above f2fs_bug_on here.

If summary page becomes non-uptodate, it seems there is a bug in vfs/mm/f2fs,
why not keep it there to detect bug?

Thanks,

> 
> I found you added the above bug_on, but it's not a big deal to remain tho. :)
> 
> 718e53fa: f2fs: enhance foreground GC
> 
> Thanks,
> 
>>
>> Thanks,
>>
>>> +				unlikely(f2fs_cp_error(sbi)))
>>> +			goto next;
>>> +
>>>  		sum = page_address(sum_page);
>>>  		f2fs_bug_on(sbi, type != GET_SUM_TYPE((&sum->footer)));
>>>  
>>>
> 
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> _______________________________________________
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> Linux-f2fs-devel@lists.sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel
> 

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Re: [PATCH] f2fs: fix wrong sum_page pointer in f2fs_gc

[Jaegeuk Kim]

On Fri, Oct 14, 2016 at 09:25:59PM +0800, Chao Yu wrote:
> On 2016/10/14 1:14, Jaegeuk Kim wrote:
> > On Thu, Oct 13, 2016 at 06:33:19PM +0800, Chao Yu wrote:
> >> Hi Jaegeuk,
> >>
> >> On 2016/10/13 7:23, Jaegeuk Kim wrote:
> >>> This patch fixes using a wrong pointer for sum_page in f2fs_gc.
> >>>
> >>> Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
> >>> ---
> >>>  fs/f2fs/gc.c | 10 +++++-----
> >>>  1 file changed, 5 insertions(+), 5 deletions(-)
> >>>
> >>> diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c
> >>> index e48142f..9c18917 100644
> >>> --- a/fs/f2fs/gc.c
> >>> +++ b/fs/f2fs/gc.c
> >>> @@ -854,16 +854,16 @@ static int do_garbage_collect(struct f2fs_sb_info *sbi,
> >>>  
> >>>  	for (segno = start_segno; segno < end_segno; segno++) {
> >>>  
> >>> -		if (get_valid_blocks(sbi, segno, 1) == 0 ||
> >>> -					unlikely(f2fs_cp_error(sbi)))
> >>> -			goto next;
> >>> -
> >>>  		/* find segment summary of victim */
> >>>  		sum_page = find_get_page(META_MAPPING(sbi),
> >>>  					GET_SUM_BLOCK(sbi, segno));
> >>> -		f2fs_bug_on(sbi, !PageUptodate(sum_page));
> >>>  		f2fs_put_page(sum_page, 0);
> >>>  
> >>> +		if (get_valid_blocks(sbi, segno, 1) == 0 ||
> >>> +				!PageUptodate(sum_page) ||
> >>
> >> Why uptodate flag of summary page can be cleared? someone truncates it?
> > 
> > Well, it looks like no problem to remove this, since it will hit
> > f2fs_cp_error(). I just intended to handle the above f2fs_bug_on here.
> 
> If summary page becomes non-uptodate, it seems there is a bug in vfs/mm/f2fs,
> why not keep it there to detect bug?

I found that the above get_sum_page() loop can give a page which is not uptodate
caused by EIO. Then, we would get the above bug_on, if we move f2fs_cp_error()
case like this patch.

Thoughts?

Thanks,

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Re: [PATCH] f2fs: fix wrong sum_page pointer in f2fs_gc

[Chao Yu]

On 2016/10/15 0:57, Jaegeuk Kim wrote:
> On Fri, Oct 14, 2016 at 09:25:59PM +0800, Chao Yu wrote:
>> On 2016/10/14 1:14, Jaegeuk Kim wrote:
>>> On Thu, Oct 13, 2016 at 06:33:19PM +0800, Chao Yu wrote:
>>>> Hi Jaegeuk,
>>>>
>>>> On 2016/10/13 7:23, Jaegeuk Kim wrote:
>>>>> This patch fixes using a wrong pointer for sum_page in f2fs_gc.
>>>>>
>>>>> Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
>>>>> ---
>>>>>  fs/f2fs/gc.c | 10 +++++-----
>>>>>  1 file changed, 5 insertions(+), 5 deletions(-)
>>>>>
>>>>> diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c
>>>>> index e48142f..9c18917 100644
>>>>> --- a/fs/f2fs/gc.c
>>>>> +++ b/fs/f2fs/gc.c
>>>>> @@ -854,16 +854,16 @@ static int do_garbage_collect(struct f2fs_sb_info *sbi,
>>>>>  
>>>>>  	for (segno = start_segno; segno < end_segno; segno++) {
>>>>>  
>>>>> -		if (get_valid_blocks(sbi, segno, 1) == 0 ||
>>>>> -					unlikely(f2fs_cp_error(sbi)))
>>>>> -			goto next;
>>>>> -
>>>>>  		/* find segment summary of victim */
>>>>>  		sum_page = find_get_page(META_MAPPING(sbi),
>>>>>  					GET_SUM_BLOCK(sbi, segno));
>>>>> -		f2fs_bug_on(sbi, !PageUptodate(sum_page));
>>>>>  		f2fs_put_page(sum_page, 0);
>>>>>  
>>>>> +		if (get_valid_blocks(sbi, segno, 1) == 0 ||
>>>>> +				!PageUptodate(sum_page) ||
>>>>
>>>> Why uptodate flag of summary page can be cleared? someone truncates it?
>>>
>>> Well, it looks like no problem to remove this, since it will hit
>>> f2fs_cp_error(). I just intended to handle the above f2fs_bug_on here.
>>
>> If summary page becomes non-uptodate, it seems there is a bug in vfs/mm/f2fs,
>> why not keep it there to detect bug?
> 
> I found that the above get_sum_page() loop can give a page which is not uptodate
> caused by EIO. Then, we would get the above bug_on, if we move f2fs_cp_error()
> case like this patch.
> 
> Thoughts?

Seems this patch has already been merged into linus' tree...

Anyway, I can understand why you remove f2fs_bug_on & add PageUptodate here, but
why should we repositon below check?

if (get_valid_blocks(sbi, segno, 1) == 0 ||
		unlikely(f2fs_cp_error(sbi)))

Thanks,

> 
> Thanks,
> 

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Re: [PATCH] f2fs: fix wrong sum_page pointer in f2fs_gc

[Jaegeuk Kim]

On Sun, Oct 23, 2016 at 08:26:15PM +0800, Chao Yu wrote:
> On 2016/10/15 0:57, Jaegeuk Kim wrote:
> > On Fri, Oct 14, 2016 at 09:25:59PM +0800, Chao Yu wrote:
> >> On 2016/10/14 1:14, Jaegeuk Kim wrote:
> >>> On Thu, Oct 13, 2016 at 06:33:19PM +0800, Chao Yu wrote:
> >>>> Hi Jaegeuk,
> >>>>
> >>>> On 2016/10/13 7:23, Jaegeuk Kim wrote:
> >>>>> This patch fixes using a wrong pointer for sum_page in f2fs_gc.
> >>>>>
> >>>>> Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
> >>>>> ---
> >>>>>  fs/f2fs/gc.c | 10 +++++-----
> >>>>>  1 file changed, 5 insertions(+), 5 deletions(-)
> >>>>>
> >>>>> diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c
> >>>>> index e48142f..9c18917 100644
> >>>>> --- a/fs/f2fs/gc.c
> >>>>> +++ b/fs/f2fs/gc.c
> >>>>> @@ -854,16 +854,16 @@ static int do_garbage_collect(struct f2fs_sb_info *sbi,
> >>>>>  
> >>>>>  	for (segno = start_segno; segno < end_segno; segno++) {
> >>>>>  
> >>>>> -		if (get_valid_blocks(sbi, segno, 1) == 0 ||
> >>>>> -					unlikely(f2fs_cp_error(sbi)))
> >>>>> -			goto next;
> >>>>> -
> >>>>>  		/* find segment summary of victim */
> >>>>>  		sum_page = find_get_page(META_MAPPING(sbi),
> >>>>>  					GET_SUM_BLOCK(sbi, segno));
> >>>>> -		f2fs_bug_on(sbi, !PageUptodate(sum_page));
> >>>>>  		f2fs_put_page(sum_page, 0);
> >>>>>  
> >>>>> +		if (get_valid_blocks(sbi, segno, 1) == 0 ||
> >>>>> +				!PageUptodate(sum_page) ||
> >>>>
> >>>> Why uptodate flag of summary page can be cleared? someone truncates it?
> >>>
> >>> Well, it looks like no problem to remove this, since it will hit
> >>> f2fs_cp_error(). I just intended to handle the above f2fs_bug_on here.
> >>
> >> If summary page becomes non-uptodate, it seems there is a bug in vfs/mm/f2fs,
> >> why not keep it there to detect bug?
> > 
> > I found that the above get_sum_page() loop can give a page which is not uptodate
> > caused by EIO. Then, we would get the above bug_on, if we move f2fs_cp_error()
> > case like this patch.
> > 
> > Thoughts?
> 
> Seems this patch has already been merged into linus' tree...

Yup.

> Anyway, I can understand why you remove f2fs_bug_on & add PageUptodate here, but
> why should we repositon below check?
> 
> if (get_valid_blocks(sbi, segno, 1) == 0 ||
> 		unlikely(f2fs_cp_error(sbi)))

Given description, this fixes using wrong sum_page pointer by:

next:
	f2fs_put_page(sum_page, 0);

Thanks,

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Re: [PATCH] f2fs: fix wrong sum_page pointer in f2fs_gc

[Chao Yu]

On 2016/10/24 5:40, Jaegeuk Kim wrote:
> On Sun, Oct 23, 2016 at 08:26:15PM +0800, Chao Yu wrote:
>> On 2016/10/15 0:57, Jaegeuk Kim wrote:
>>> On Fri, Oct 14, 2016 at 09:25:59PM +0800, Chao Yu wrote:
>>>> On 2016/10/14 1:14, Jaegeuk Kim wrote:
>>>>> On Thu, Oct 13, 2016 at 06:33:19PM +0800, Chao Yu wrote:
>>>>>> Hi Jaegeuk,
>>>>>>
>>>>>> On 2016/10/13 7:23, Jaegeuk Kim wrote:
>>>>>>> This patch fixes using a wrong pointer for sum_page in f2fs_gc.
>>>>>>>
>>>>>>> Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
>>>>>>> ---
>>>>>>>  fs/f2fs/gc.c | 10 +++++-----
>>>>>>>  1 file changed, 5 insertions(+), 5 deletions(-)
>>>>>>>
>>>>>>> diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c
>>>>>>> index e48142f..9c18917 100644
>>>>>>> --- a/fs/f2fs/gc.c
>>>>>>> +++ b/fs/f2fs/gc.c
>>>>>>> @@ -854,16 +854,16 @@ static int do_garbage_collect(struct f2fs_sb_info *sbi,
>>>>>>>  
>>>>>>>  	for (segno = start_segno; segno < end_segno; segno++) {
>>>>>>>  
>>>>>>> -		if (get_valid_blocks(sbi, segno, 1) == 0 ||
>>>>>>> -					unlikely(f2fs_cp_error(sbi)))
>>>>>>> -			goto next;
>>>>>>> -
>>>>>>>  		/* find segment summary of victim */
>>>>>>>  		sum_page = find_get_page(META_MAPPING(sbi),
>>>>>>>  					GET_SUM_BLOCK(sbi, segno));
>>>>>>> -		f2fs_bug_on(sbi, !PageUptodate(sum_page));
>>>>>>>  		f2fs_put_page(sum_page, 0);
>>>>>>>  
>>>>>>> +		if (get_valid_blocks(sbi, segno, 1) == 0 ||
>>>>>>> +				!PageUptodate(sum_page) ||
>>>>>>
>>>>>> Why uptodate flag of summary page can be cleared? someone truncates it?
>>>>>
>>>>> Well, it looks like no problem to remove this, since it will hit
>>>>> f2fs_cp_error(). I just intended to handle the above f2fs_bug_on here.
>>>>
>>>> If summary page becomes non-uptodate, it seems there is a bug in vfs/mm/f2fs,
>>>> why not keep it there to detect bug?
>>>
>>> I found that the above get_sum_page() loop can give a page which is not uptodate
>>> caused by EIO. Then, we would get the above bug_on, if we move f2fs_cp_error()
>>> case like this patch.
>>>
>>> Thoughts?
>>
>> Seems this patch has already been merged into linus' tree...
> 
> Yup.
> 
>> Anyway, I can understand why you remove f2fs_bug_on & add PageUptodate here, but
>> why should we repositon below check?
>>
>> if (get_valid_blocks(sbi, segno, 1) == 0 ||
>> 		unlikely(f2fs_cp_error(sbi)))
> 
> Given description, this fixes using wrong sum_page pointer by:
> 
> next:
> 	f2fs_put_page(sum_page, 0);

That's right, I'm missing this reference. Thanks for the explanation. :)

thanks,

> 
> Thanks,
> 
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> 
> 


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