[PATCH] f2fs: fix conflict between atomic_write and truncate

[PATCH] f2fs: fix conflict between atomic_write and truncate

[Hou Pengyang]

In fsync_node_pages path, after locking the last_page for setting dirty,
we should check if the page has been truncated. Or there may be a mem leak,
as this dirty last_page will NOT be found in next page-cache travese.

This patch adds page->mapping checking, and will NOT rewrite the page if
it has been truncated.

Signed-off-by: Hou Pengyang <houpengyang@huawei.com>
---
 fs/f2fs/node.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c
index c1bbfdc..78c5b50 100644
--- a/fs/f2fs/node.c
+++ b/fs/f2fs/node.c
@@ -1410,6 +1410,11 @@ int fsync_node_pages(struct f2fs_sb_info *sbi, struct inode *inode,
 			"Retry to write fsync mark: ino=%u, idx=%lx",
 					ino, last_page->index);
 		lock_page(last_page);
+		if (unlikely(last_page->mapping != NODE_MAPPING(sbi))) {
+			unlock_page(last_page);
+			f2fs_put_page(last_page, 0);
+			goto out;
+		}
 		f2fs_wait_on_page_writeback(last_page, NODE, true);
 		set_page_dirty(last_page);
 		unlock_page(last_page);
-- 
2.10.1


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Re: [PATCH] f2fs: fix conflict between atomic_write and truncate

[Jaegeuk Kim]

Hi Pengyang,

On 12/12, Hou Pengyang wrote:
> In fsync_node_pages path, after locking the last_page for setting dirty,
> we should check if the page has been truncated. Or there may be a mem leak,
> as this dirty last_page will NOT be found in next page-cache travese.
> 
> This patch adds page->mapping checking, and will NOT rewrite the page if
> it has been truncated.
> 
> Signed-off-by: Hou Pengyang <houpengyang@huawei.com>
> ---
>  fs/f2fs/node.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c
> index c1bbfdc..78c5b50 100644
> --- a/fs/f2fs/node.c
> +++ b/fs/f2fs/node.c
> @@ -1410,6 +1410,11 @@ int fsync_node_pages(struct f2fs_sb_info *sbi, struct inode *inode,
>  			"Retry to write fsync mark: ino=%u, idx=%lx",
>  					ino, last_page->index);
>  		lock_page(last_page);

We grabbed a reference count for this last_page, and thus, it won't be released.
Something that I missed?

Thanks,

> +		if (unlikely(last_page->mapping != NODE_MAPPING(sbi))) {
> +			unlock_page(last_page);
> +			f2fs_put_page(last_page, 0);
> +			goto out;
> +		}
>  		f2fs_wait_on_page_writeback(last_page, NODE, true);
>  		set_page_dirty(last_page);
>  		unlock_page(last_page);
> -- 
> 2.10.1
> 
> 
> ------------------------------------------------------------------------------
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> Access to Intel Xeon Phi processor-based developer platforms.
> With one year of Intel Parallel Studio XE.
> Training and support from Colfax.
> Order your platform today.http://sdm.link/xeonphi
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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 conflict between atomic_write and truncate

[Hou Pengyang]

On 2016/12/13 3:18, Jaegeuk Kim wrote:
> Hi Pengyang,
>
Hi, kim,
> On 12/12, Hou Pengyang wrote:
>> In fsync_node_pages path, after locking the last_page for setting dirty,
>> we should check if the page has been truncated. Or there may be a mem leak,
>> as this dirty last_page will NOT be found in next page-cache travese.
>>
>> This patch adds page->mapping checking, and will NOT rewrite the page if
>> it has been truncated.
>>
>> Signed-off-by: Hou Pengyang <houpengyang@huawei.com>
>> ---
>>   fs/f2fs/node.c | 5 +++++
>>   1 file changed, 5 insertions(+)
>>
>> diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c
>> index c1bbfdc..78c5b50 100644
>> --- a/fs/f2fs/node.c
>> +++ b/fs/f2fs/node.c
>> @@ -1410,6 +1410,11 @@ int fsync_node_pages(struct f2fs_sb_info *sbi, struct inode *inode,
>>   			"Retry to write fsync mark: ino=%u, idx=%lx",
>>   					ino, last_page->index);
>>   		lock_page(last_page);
>
> We grabbed a reference count for this last_page, and thus, it won't be released.
> Something that I missed?
>
Some path (e.g. shrink) would NOT release the page if we've grabbed it,
But truncate operation will invalidate the page from page-cache
regardless of the page reference.

Patch: 0fac558b965 f2fs: make atomic/volatile operation exclusive
seems fix this issue by adding inode_lock(inode) to avoid conflict
between atomic/volatile and truncate operation.

But this patch makes codes more robust.

Thanks.

> Thanks,
>
>> +		if (unlikely(last_page->mapping != NODE_MAPPING(sbi))) {
>> +			unlock_page(last_page);
>> +			f2fs_put_page(last_page, 0);
>> +			goto out;
>> +		}
>>   		f2fs_wait_on_page_writeback(last_page, NODE, true);
>>   		set_page_dirty(last_page);
>>   		unlock_page(last_page);
>> --
>> 2.10.1
>>
>>
>> ------------------------------------------------------------------------------
>> Developer Access Program for Intel Xeon Phi Processors
>> Access to Intel Xeon Phi processor-based developer platforms.
>> With one year of Intel Parallel Studio XE.
>> Training and support from Colfax.
>> Order your platform today.http://sdm.link/xeonphi
>> _______________________________________________
>> Linux-f2fs-devel mailing list
>> Linux-f2fs-devel@lists.sourceforge.net
>> https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel
>
> .
>



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Re: [PATCH] f2fs: fix conflict between atomic_write and truncate

[Jaegeuk Kim]

Hi,

On 12/13, Hou Pengyang wrote:
> On 2016/12/13 3:18, Jaegeuk Kim wrote:
> > Hi Pengyang,
> >
> Hi, kim,
> > On 12/12, Hou Pengyang wrote:
> >> In fsync_node_pages path, after locking the last_page for setting dirty,
> >> we should check if the page has been truncated. Or there may be a mem leak,
> >> as this dirty last_page will NOT be found in next page-cache travese.
> >>
> >> This patch adds page->mapping checking, and will NOT rewrite the page if
> >> it has been truncated.
> >>
> >> Signed-off-by: Hou Pengyang <houpengyang@huawei.com>
> >> ---
> >>   fs/f2fs/node.c | 5 +++++
> >>   1 file changed, 5 insertions(+)
> >>
> >> diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c
> >> index c1bbfdc..78c5b50 100644
> >> --- a/fs/f2fs/node.c
> >> +++ b/fs/f2fs/node.c
> >> @@ -1410,6 +1410,11 @@ int fsync_node_pages(struct f2fs_sb_info *sbi, struct inode *inode,
> >>   			"Retry to write fsync mark: ino=%u, idx=%lx",
> >>   					ino, last_page->index);
> >>   		lock_page(last_page);
> >
> > We grabbed a reference count for this last_page, and thus, it won't be released.
> > Something that I missed?
> >
> Some path (e.g. shrink) would NOT release the page if we've grabbed it,
> But truncate operation will invalidate the page from page-cache
> regardless of the page reference.

This is a node page, and we guarantee that nobody will truncate them.
Did you hit an issue regarding to this?

Thanks,

> Patch: 0fac558b965 f2fs: make atomic/volatile operation exclusive
> seems fix this issue by adding inode_lock(inode) to avoid conflict
> between atomic/volatile and truncate operation.
> 
> But this patch makes codes more robust.
> 
> Thanks.
> 
> > Thanks,
> >
> >> +		if (unlikely(last_page->mapping != NODE_MAPPING(sbi))) {
> >> +			unlock_page(last_page);
> >> +			f2fs_put_page(last_page, 0);
> >> +			goto out;
> >> +		}
> >>   		f2fs_wait_on_page_writeback(last_page, NODE, true);
> >>   		set_page_dirty(last_page);
> >>   		unlock_page(last_page);
> >> --
> >> 2.10.1
> >>
> >>
> >> ------------------------------------------------------------------------------
> >> Developer Access Program for Intel Xeon Phi Processors
> >> Access to Intel Xeon Phi processor-based developer platforms.
> >> With one year of Intel Parallel Studio XE.
> >> Training and support from Colfax.
> >> Order your platform today.http://sdm.link/xeonphi
> >> _______________________________________________
> >> Linux-f2fs-devel mailing list
> >> Linux-f2fs-devel@lists.sourceforge.net
> >> https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel
> >
> > .
> >
> 
> 
> 
> ------------------------------------------------------------------------------
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> engaging tech sites, SlashDot.org! http://sdm.link/slashdot
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Re: [PATCH] f2fs: fix conflict between atomic_write and truncate

[Hou Pengyang]

On 2016/12/13 9:21, Jaegeuk Kim wrote:
> Hi,
>
> On 12/13, Hou Pengyang wrote:
>> On 2016/12/13 3:18, Jaegeuk Kim wrote:
>>> Hi Pengyang,
>>>
>> Hi, kim,
>>> On 12/12, Hou Pengyang wrote:
>>>> In fsync_node_pages path, after locking the last_page for setting dirty,
>>>> we should check if the page has been truncated. Or there may be a mem leak,
>>>> as this dirty last_page will NOT be found in next page-cache travese.
>>>>
>>>> This patch adds page->mapping checking, and will NOT rewrite the page if
>>>> it has been truncated.
>>>>
>>>> Signed-off-by: Hou Pengyang <houpengyang@huawei.com>
>>>> ---
>>>>    fs/f2fs/node.c | 5 +++++
>>>>    1 file changed, 5 insertions(+)
>>>>
>>>> diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c
>>>> index c1bbfdc..78c5b50 100644
>>>> --- a/fs/f2fs/node.c
>>>> +++ b/fs/f2fs/node.c
>>>> @@ -1410,6 +1410,11 @@ int fsync_node_pages(struct f2fs_sb_info *sbi, struct inode *inode,
>>>>    			"Retry to write fsync mark: ino=%u, idx=%lx",
>>>>    					ino, last_page->index);
>>>>    		lock_page(last_page);
>>>
>>> We grabbed a reference count for this last_page, and thus, it won't be released.
>>> Something that I missed?
>>>
>> Some path (e.g. shrink) would NOT release the page if we've grabbed it,
>> But truncate operation will invalidate the page from page-cache
>> regardless of the page reference.
>
> This is a node page, and we guarantee that nobody will truncate them.
> Did you hit an issue regarding to this?
>
As my view, the truncate operations may lead to the related node pages 
being truncated, or I miss something.

> Thanks,
>
>> Patch: 0fac558b965 f2fs: make atomic/volatile operation exclusive
>> seems fix this issue by adding inode_lock(inode) to avoid conflict
>> between atomic/volatile and truncate operation.
>>
>> But this patch makes codes more robust.
>>
>> Thanks.
>>
>>> Thanks,
>>>
>>>> +		if (unlikely(last_page->mapping != NODE_MAPPING(sbi))) {
>>>> +			unlock_page(last_page);
>>>> +			f2fs_put_page(last_page, 0);
>>>> +			goto out;
>>>> +		}
>>>>    		f2fs_wait_on_page_writeback(last_page, NODE, true);
>>>>    		set_page_dirty(last_page);
>>>>    		unlock_page(last_page);
>>>> --
>>>> 2.10.1
>>>>
>>>>
>>>> ------------------------------------------------------------------------------
>>>> Developer Access Program for Intel Xeon Phi Processors
>>>> Access to Intel Xeon Phi processor-based developer platforms.
>>>> With one year of Intel Parallel Studio XE.
>>>> Training and support from Colfax.
>>>> Order your platform today.http://sdm.link/xeonphi
>>>> _______________________________________________
>>>> Linux-f2fs-devel mailing list
>>>> Linux-f2fs-devel@lists.sourceforge.net
>>>> https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel
>>>
>>> .
>>>
>>
>>
>>
>> ------------------------------------------------------------------------------
>> Check out the vibrant tech community on one of the world's most
>> engaging tech sites, SlashDot.org! http://sdm.link/slashdot
>> _______________________________________________
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>> Linux-f2fs-devel@lists.sourceforge.net
>> https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel
>
> .
>



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