[PATCH] f2fs: skip f2fs_preallocate_blocks() for overwrite case

[PATCH] f2fs: skip f2fs_preallocate_blocks() for overwrite case

[Chao Yu]

In f2fs_file_write_iter(), let's use f2fs_overwrite_io() to
check whethere it is overwrite case, for such case, we can skip
f2fs_preallocate_blocks() in order to avoid f2fs_do_map_lock(),
which may be blocked by checkpoint() potentially.

Signed-off-by: Chao Yu <chao@kernel.org>
---
 fs/f2fs/file.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
index 13deae03df06..51fecb2f4db5 100644
--- a/fs/f2fs/file.c
+++ b/fs/f2fs/file.c
@@ -4321,6 +4321,10 @@ static ssize_t f2fs_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
 		preallocated = true;
 		target_size = iocb->ki_pos + iov_iter_count(from);
 
+		if (f2fs_overwrite_io(inode, iocb->ki_pos,
+						iov_iter_count(from)))
+			goto write;
+
 		err = f2fs_preallocate_blocks(iocb, from);
 		if (err) {
 out_err:
-- 
2.32.0

[f2fs-dev] [PATCH] f2fs: skip f2fs_preallocate_blocks() for overwrite case

[Chao Yu]

In f2fs_file_write_iter(), let's use f2fs_overwrite_io() to
check whethere it is overwrite case, for such case, we can skip
f2fs_preallocate_blocks() in order to avoid f2fs_do_map_lock(),
which may be blocked by checkpoint() potentially.

Signed-off-by: Chao Yu <chao@kernel.org>
---
 fs/f2fs/file.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
index 13deae03df06..51fecb2f4db5 100644
--- a/fs/f2fs/file.c
+++ b/fs/f2fs/file.c
@@ -4321,6 +4321,10 @@ static ssize_t f2fs_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
 		preallocated = true;
 		target_size = iocb->ki_pos + iov_iter_count(from);
 
+		if (f2fs_overwrite_io(inode, iocb->ki_pos,
+						iov_iter_count(from)))
+			goto write;
+
 		err = f2fs_preallocate_blocks(iocb, from);
 		if (err) {
 out_err:
-- 
2.32.0



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Re: [PATCH] f2fs: skip f2fs_preallocate_blocks() for overwrite case

[Jaegeuk Kim]

On 09/28, Chao Yu wrote:
> In f2fs_file_write_iter(), let's use f2fs_overwrite_io() to
> check whethere it is overwrite case, for such case, we can skip
> f2fs_preallocate_blocks() in order to avoid f2fs_do_map_lock(),
> which may be blocked by checkpoint() potentially.
> 
> Signed-off-by: Chao Yu <chao@kernel.org>
> ---
>  fs/f2fs/file.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
> index 13deae03df06..51fecb2f4db5 100644
> --- a/fs/f2fs/file.c
> +++ b/fs/f2fs/file.c
> @@ -4321,6 +4321,10 @@ static ssize_t f2fs_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
>  		preallocated = true;
>  		target_size = iocb->ki_pos + iov_iter_count(from);
>  
> +		if (f2fs_overwrite_io(inode, iocb->ki_pos,
> +						iov_iter_count(from)))
> +			goto write;

This calls f2fs_map_blocks() which can be duplicate, if it's not the overwirte
case. Do we have other benefit?

> +
>  		err = f2fs_preallocate_blocks(iocb, from);
>  		if (err) {
>  out_err:
> -- 
> 2.32.0

Re: [f2fs-dev] [PATCH] f2fs: skip f2fs_preallocate_blocks() for overwrite case

[Jaegeuk Kim]

On 09/28, Chao Yu wrote:
> In f2fs_file_write_iter(), let's use f2fs_overwrite_io() to
> check whethere it is overwrite case, for such case, we can skip
> f2fs_preallocate_blocks() in order to avoid f2fs_do_map_lock(),
> which may be blocked by checkpoint() potentially.
> 
> Signed-off-by: Chao Yu <chao@kernel.org>
> ---
>  fs/f2fs/file.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
> index 13deae03df06..51fecb2f4db5 100644
> --- a/fs/f2fs/file.c
> +++ b/fs/f2fs/file.c
> @@ -4321,6 +4321,10 @@ static ssize_t f2fs_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
>  		preallocated = true;
>  		target_size = iocb->ki_pos + iov_iter_count(from);
>  
> +		if (f2fs_overwrite_io(inode, iocb->ki_pos,
> +						iov_iter_count(from)))
> +			goto write;

This calls f2fs_map_blocks() which can be duplicate, if it's not the overwirte
case. Do we have other benefit?

> +
>  		err = f2fs_preallocate_blocks(iocb, from);
>  		if (err) {
>  out_err:
> -- 
> 2.32.0


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Re: [PATCH] f2fs: skip f2fs_preallocate_blocks() for overwrite case

[Chao Yu]

On 2021/9/29 3:08, Jaegeuk Kim wrote:
> On 09/28, Chao Yu wrote:
>> In f2fs_file_write_iter(), let's use f2fs_overwrite_io() to
>> check whethere it is overwrite case, for such case, we can skip
>> f2fs_preallocate_blocks() in order to avoid f2fs_do_map_lock(),
>> which may be blocked by checkpoint() potentially.
>>
>> Signed-off-by: Chao Yu <chao@kernel.org>
>> ---
>>   fs/f2fs/file.c | 4 ++++
>>   1 file changed, 4 insertions(+)
>>
>> diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
>> index 13deae03df06..51fecb2f4db5 100644
>> --- a/fs/f2fs/file.c
>> +++ b/fs/f2fs/file.c
>> @@ -4321,6 +4321,10 @@ static ssize_t f2fs_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
>>   		preallocated = true;
>>   		target_size = iocb->ki_pos + iov_iter_count(from);
>>   
>> +		if (f2fs_overwrite_io(inode, iocb->ki_pos,
>> +						iov_iter_count(from)))
>> +			goto write;
> 
> This calls f2fs_map_blocks() which can be duplicate, if it's not the overwirte
> case. Do we have other benefit?

f2fs_overwrite_io() will break for append write case w/ below check:

	if (pos + len > i_size_read(inode))
		return false;

I guess we may only suffer double f2fs_map_blocks() for write hole
case, e.g. truncate to large size & write inside the filesize. For
this case, how about adding a condition to allow double f2fs_map_blocks()
only if write size is smaller than a threshold?

Thanks,

> 
>> +
>>   		err = f2fs_preallocate_blocks(iocb, from);
>>   		if (err) {
>>   out_err:
>> -- 
>> 2.32.0

Re: [f2fs-dev] [PATCH] f2fs: skip f2fs_preallocate_blocks() for overwrite case

[Chao Yu]

On 2021/9/29 3:08, Jaegeuk Kim wrote:
> On 09/28, Chao Yu wrote:
>> In f2fs_file_write_iter(), let's use f2fs_overwrite_io() to
>> check whethere it is overwrite case, for such case, we can skip
>> f2fs_preallocate_blocks() in order to avoid f2fs_do_map_lock(),
>> which may be blocked by checkpoint() potentially.
>>
>> Signed-off-by: Chao Yu <chao@kernel.org>
>> ---
>>   fs/f2fs/file.c | 4 ++++
>>   1 file changed, 4 insertions(+)
>>
>> diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
>> index 13deae03df06..51fecb2f4db5 100644
>> --- a/fs/f2fs/file.c
>> +++ b/fs/f2fs/file.c
>> @@ -4321,6 +4321,10 @@ static ssize_t f2fs_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
>>   		preallocated = true;
>>   		target_size = iocb->ki_pos + iov_iter_count(from);
>>   
>> +		if (f2fs_overwrite_io(inode, iocb->ki_pos,
>> +						iov_iter_count(from)))
>> +			goto write;
> 
> This calls f2fs_map_blocks() which can be duplicate, if it's not the overwirte
> case. Do we have other benefit?

f2fs_overwrite_io() will break for append write case w/ below check:

	if (pos + len > i_size_read(inode))
		return false;

I guess we may only suffer double f2fs_map_blocks() for write hole
case, e.g. truncate to large size & write inside the filesize. For
this case, how about adding a condition to allow double f2fs_map_blocks()
only if write size is smaller than a threshold?

Thanks,

> 
>> +
>>   		err = f2fs_preallocate_blocks(iocb, from);
>>   		if (err) {
>>   out_err:
>> -- 
>> 2.32.0


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Re: [f2fs-dev] [PATCH] f2fs: skip f2fs_preallocate_blocks() for overwrite case

[Chao Yu]

Ping,

On 2021/9/29 8:05, Chao Yu wrote:
> On 2021/9/29 3:08, Jaegeuk Kim wrote:
>> On 09/28, Chao Yu wrote:
>>> In f2fs_file_write_iter(), let's use f2fs_overwrite_io() to
>>> check whethere it is overwrite case, for such case, we can skip
>>> f2fs_preallocate_blocks() in order to avoid f2fs_do_map_lock(),
>>> which may be blocked by checkpoint() potentially.
>>>
>>> Signed-off-by: Chao Yu <chao@kernel.org>
>>> ---
>>>   fs/f2fs/file.c | 4 ++++
>>>   1 file changed, 4 insertions(+)
>>>
>>> diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
>>> index 13deae03df06..51fecb2f4db5 100644
>>> --- a/fs/f2fs/file.c
>>> +++ b/fs/f2fs/file.c
>>> @@ -4321,6 +4321,10 @@ static ssize_t f2fs_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
>>>           preallocated = true;
>>>           target_size = iocb->ki_pos + iov_iter_count(from);
>>> +        if (f2fs_overwrite_io(inode, iocb->ki_pos,
>>> +                        iov_iter_count(from)))
>>> +            goto write;
>>
>> This calls f2fs_map_blocks() which can be duplicate, if it's not the overwirte
>> case. Do we have other benefit?
> 
> f2fs_overwrite_io() will break for append write case w/ below check:
> 
>      if (pos + len > i_size_read(inode))
>          return false;
> 
> I guess we may only suffer double f2fs_map_blocks() for write hole
> case, e.g. truncate to large size & write inside the filesize. For
> this case, how about adding a condition to allow double f2fs_map_blocks()
> only if write size is smaller than a threshold?
> 
> Thanks,
> 
>>
>>> +
>>>           err = f2fs_preallocate_blocks(iocb, from);
>>>           if (err) {
>>>   out_err:
>>> -- 
>>> 2.32.0
> 
> 
> _______________________________________________
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Re: [f2fs-dev] [PATCH] f2fs: skip f2fs_preallocate_blocks() for overwrite case

[Chao Yu]

Ping,

On 2021/9/29 8:05, Chao Yu wrote:
> On 2021/9/29 3:08, Jaegeuk Kim wrote:
>> On 09/28, Chao Yu wrote:
>>> In f2fs_file_write_iter(), let's use f2fs_overwrite_io() to
>>> check whethere it is overwrite case, for such case, we can skip
>>> f2fs_preallocate_blocks() in order to avoid f2fs_do_map_lock(),
>>> which may be blocked by checkpoint() potentially.
>>>
>>> Signed-off-by: Chao Yu <chao@kernel.org>
>>> ---
>>>   fs/f2fs/file.c | 4 ++++
>>>   1 file changed, 4 insertions(+)
>>>
>>> diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
>>> index 13deae03df06..51fecb2f4db5 100644
>>> --- a/fs/f2fs/file.c
>>> +++ b/fs/f2fs/file.c
>>> @@ -4321,6 +4321,10 @@ static ssize_t f2fs_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
>>>           preallocated = true;
>>>           target_size = iocb->ki_pos + iov_iter_count(from);
>>> +        if (f2fs_overwrite_io(inode, iocb->ki_pos,
>>> +                        iov_iter_count(from)))
>>> +            goto write;
>>
>> This calls f2fs_map_blocks() which can be duplicate, if it's not the overwirte
>> case. Do we have other benefit?
> 
> f2fs_overwrite_io() will break for append write case w/ below check:
> 
>      if (pos + len > i_size_read(inode))
>          return false;
> 
> I guess we may only suffer double f2fs_map_blocks() for write hole
> case, e.g. truncate to large size & write inside the filesize. For
> this case, how about adding a condition to allow double f2fs_map_blocks()
> only if write size is smaller than a threshold?
> 
> Thanks,
> 
>>
>>> +
>>>           err = f2fs_preallocate_blocks(iocb, from);
>>>           if (err) {
>>>   out_err:
>>> -- 
>>> 2.32.0
> 
> 
> _______________________________________________
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Re: [f2fs-dev] [PATCH] f2fs: skip f2fs_preallocate_blocks() for overwrite case

[Jaegeuk Kim]

On 10/29, Chao Yu wrote:
> Ping,
> 
> On 2021/9/29 8:05, Chao Yu wrote:
> > On 2021/9/29 3:08, Jaegeuk Kim wrote:
> > > On 09/28, Chao Yu wrote:
> > > > In f2fs_file_write_iter(), let's use f2fs_overwrite_io() to
> > > > check whethere it is overwrite case, for such case, we can skip
> > > > f2fs_preallocate_blocks() in order to avoid f2fs_do_map_lock(),
> > > > which may be blocked by checkpoint() potentially.
> > > > 
> > > > Signed-off-by: Chao Yu <chao@kernel.org>
> > > > ---
> > > >   fs/f2fs/file.c | 4 ++++
> > > >   1 file changed, 4 insertions(+)
> > > > 
> > > > diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
> > > > index 13deae03df06..51fecb2f4db5 100644
> > > > --- a/fs/f2fs/file.c
> > > > +++ b/fs/f2fs/file.c
> > > > @@ -4321,6 +4321,10 @@ static ssize_t f2fs_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
> > > >           preallocated = true;
> > > >           target_size = iocb->ki_pos + iov_iter_count(from);
> > > > +        if (f2fs_overwrite_io(inode, iocb->ki_pos,
> > > > +                        iov_iter_count(from)))
> > > > +            goto write;
> > > 
> > > This calls f2fs_map_blocks() which can be duplicate, if it's not the overwirte
> > > case. Do we have other benefit?
> > 
> > f2fs_overwrite_io() will break for append write case w/ below check:
> > 
> >      if (pos + len > i_size_read(inode))
> >          return false;
> > 
> > I guess we may only suffer double f2fs_map_blocks() for write hole
> > case, e.g. truncate to large size & write inside the filesize. For
> > this case, how about adding a condition to allow double f2fs_map_blocks()
> > only if write size is smaller than a threshold?

I still don't see the benefit much to do double f2fs_map_blocks. What is the
problem here?

> > 
> > Thanks,
> > 
> > > 
> > > > +
> > > >           err = f2fs_preallocate_blocks(iocb, from);
> > > >           if (err) {
> > > >   out_err:
> > > > -- 
> > > > 2.32.0
> > 
> > 
> > _______________________________________________
> > Linux-f2fs-devel mailing list
> > Linux-f2fs-devel@lists.sourceforge.net
> > https://apc01.safelinks.protection.outlook.com/?url=https%3A%2F%2Flists.sourceforge.net%2Flists%2Flistinfo%2Flinux-f2fs-devel&amp;data=04%7C01%7Cchao.yu%40oppo.com%7C421c06812eba4f922b0908d982dcdcc5%7Cf1905eb1c35341c5951662b4a54b5ee6%7C0%7C0%7C637684707374940190%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&amp;sdata=u22eEWDAPaAZCyISyjTUOtQDLDuyKxTnNCI3eSwwWro%3D&amp;reserved=0

Re: [f2fs-dev] [PATCH] f2fs: skip f2fs_preallocate_blocks() for overwrite case

[Jaegeuk Kim]

On 10/29, Chao Yu wrote:
> Ping,
> 
> On 2021/9/29 8:05, Chao Yu wrote:
> > On 2021/9/29 3:08, Jaegeuk Kim wrote:
> > > On 09/28, Chao Yu wrote:
> > > > In f2fs_file_write_iter(), let's use f2fs_overwrite_io() to
> > > > check whethere it is overwrite case, for such case, we can skip
> > > > f2fs_preallocate_blocks() in order to avoid f2fs_do_map_lock(),
> > > > which may be blocked by checkpoint() potentially.
> > > > 
> > > > Signed-off-by: Chao Yu <chao@kernel.org>
> > > > ---
> > > >   fs/f2fs/file.c | 4 ++++
> > > >   1 file changed, 4 insertions(+)
> > > > 
> > > > diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
> > > > index 13deae03df06..51fecb2f4db5 100644
> > > > --- a/fs/f2fs/file.c
> > > > +++ b/fs/f2fs/file.c
> > > > @@ -4321,6 +4321,10 @@ static ssize_t f2fs_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
> > > >           preallocated = true;
> > > >           target_size = iocb->ki_pos + iov_iter_count(from);
> > > > +        if (f2fs_overwrite_io(inode, iocb->ki_pos,
> > > > +                        iov_iter_count(from)))
> > > > +            goto write;
> > > 
> > > This calls f2fs_map_blocks() which can be duplicate, if it's not the overwirte
> > > case. Do we have other benefit?
> > 
> > f2fs_overwrite_io() will break for append write case w/ below check:
> > 
> >      if (pos + len > i_size_read(inode))
> >          return false;
> > 
> > I guess we may only suffer double f2fs_map_blocks() for write hole
> > case, e.g. truncate to large size & write inside the filesize. For
> > this case, how about adding a condition to allow double f2fs_map_blocks()
> > only if write size is smaller than a threshold?

I still don't see the benefit much to do double f2fs_map_blocks. What is the
problem here?

> > 
> > Thanks,
> > 
> > > 
> > > > +
> > > >           err = f2fs_preallocate_blocks(iocb, from);
> > > >           if (err) {
> > > >   out_err:
> > > > -- 
> > > > 2.32.0
> > 
> > 
> > _______________________________________________
> > Linux-f2fs-devel mailing list
> > Linux-f2fs-devel@lists.sourceforge.net
> > https://apc01.safelinks.protection.outlook.com/?url=https%3A%2F%2Flists.sourceforge.net%2Flists%2Flistinfo%2Flinux-f2fs-devel&amp;data=04%7C01%7Cchao.yu%40oppo.com%7C421c06812eba4f922b0908d982dcdcc5%7Cf1905eb1c35341c5951662b4a54b5ee6%7C0%7C0%7C637684707374940190%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&amp;sdata=u22eEWDAPaAZCyISyjTUOtQDLDuyKxTnNCI3eSwwWro%3D&amp;reserved=0


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Re: [f2fs-dev] [PATCH] f2fs: skip f2fs_preallocate_blocks() for overwrite case

[Chao Yu]

On 2021/10/30 1:43, Jaegeuk Kim wrote:
> On 10/29, Chao Yu wrote:
>> Ping,
>>
>> On 2021/9/29 8:05, Chao Yu wrote:
>>> On 2021/9/29 3:08, Jaegeuk Kim wrote:
>>>> On 09/28, Chao Yu wrote:
>>>>> In f2fs_file_write_iter(), let's use f2fs_overwrite_io() to
>>>>> check whethere it is overwrite case, for such case, we can skip
>>>>> f2fs_preallocate_blocks() in order to avoid f2fs_do_map_lock(),
>>>>> which may be blocked by checkpoint() potentially.
>>>>>
>>>>> Signed-off-by: Chao Yu <chao@kernel.org>
>>>>> ---
>>>>>    fs/f2fs/file.c | 4 ++++
>>>>>    1 file changed, 4 insertions(+)
>>>>>
>>>>> diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
>>>>> index 13deae03df06..51fecb2f4db5 100644
>>>>> --- a/fs/f2fs/file.c
>>>>> +++ b/fs/f2fs/file.c
>>>>> @@ -4321,6 +4321,10 @@ static ssize_t f2fs_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
>>>>>            preallocated = true;
>>>>>            target_size = iocb->ki_pos + iov_iter_count(from);
>>>>> +        if (f2fs_overwrite_io(inode, iocb->ki_pos,
>>>>> +                        iov_iter_count(from)))
>>>>> +            goto write;
>>>>
>>>> This calls f2fs_map_blocks() which can be duplicate, if it's not the overwirte
>>>> case. Do we have other benefit?
>>>
>>> f2fs_overwrite_io() will break for append write case w/ below check:
>>>
>>>       if (pos + len > i_size_read(inode))
>>>           return false;
>>>
>>> I guess we may only suffer double f2fs_map_blocks() for write hole
>>> case, e.g. truncate to large size & write inside the filesize. For
>>> this case, how about adding a condition to allow double f2fs_map_blocks()
>>> only if write size is smaller than a threshold?
> 
> I still don't see the benefit much to do double f2fs_map_blocks. What is the
> problem here?

There is potential hangtask happened during swapfile's writeback:

- loop_kthread_worker_fn
  - kthread_worker_fn
   - loop_queue_work
    - lo_rw_aio
     - f2fs_file_write_iter
      - f2fs_preallocate_blocks
       - f2fs_map_blocks
        - down_read
         - rwsem_down_read_slowpath
          - schedule

I try to mitigate such issue by preallocating swapfile's block address and
avoid f2fs_do_map_lock() as much as possible in swapfile's writeback path...

Thanks,

> 
>>>
>>> Thanks,
>>>
>>>>
>>>>> +
>>>>>            err = f2fs_preallocate_blocks(iocb, from);
>>>>>            if (err) {
>>>>>    out_err:
>>>>> -- 
>>>>> 2.32.0
>>>
>>>
>>> _______________________________________________
>>> Linux-f2fs-devel mailing list
>>> Linux-f2fs-devel@lists.sourceforge.net
>>> https://apc01.safelinks.protection.outlook.com/?url=https%3A%2F%2Flists.sourceforge.net%2Flists%2Flistinfo%2Flinux-f2fs-devel&amp;data=04%7C01%7Cchao.yu%40oppo.com%7C421c06812eba4f922b0908d982dcdcc5%7Cf1905eb1c35341c5951662b4a54b5ee6%7C0%7C0%7C637684707374940190%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&amp;sdata=u22eEWDAPaAZCyISyjTUOtQDLDuyKxTnNCI3eSwwWro%3D&amp;reserved=0


_______________________________________________
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Re: [f2fs-dev] [PATCH] f2fs: skip f2fs_preallocate_blocks() for overwrite case

[Chao Yu]

On 2021/10/30 1:43, Jaegeuk Kim wrote:
> On 10/29, Chao Yu wrote:
>> Ping,
>>
>> On 2021/9/29 8:05, Chao Yu wrote:
>>> On 2021/9/29 3:08, Jaegeuk Kim wrote:
>>>> On 09/28, Chao Yu wrote:
>>>>> In f2fs_file_write_iter(), let's use f2fs_overwrite_io() to
>>>>> check whethere it is overwrite case, for such case, we can skip
>>>>> f2fs_preallocate_blocks() in order to avoid f2fs_do_map_lock(),
>>>>> which may be blocked by checkpoint() potentially.
>>>>>
>>>>> Signed-off-by: Chao Yu <chao@kernel.org>
>>>>> ---
>>>>>    fs/f2fs/file.c | 4 ++++
>>>>>    1 file changed, 4 insertions(+)
>>>>>
>>>>> diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
>>>>> index 13deae03df06..51fecb2f4db5 100644
>>>>> --- a/fs/f2fs/file.c
>>>>> +++ b/fs/f2fs/file.c
>>>>> @@ -4321,6 +4321,10 @@ static ssize_t f2fs_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
>>>>>            preallocated = true;
>>>>>            target_size = iocb->ki_pos + iov_iter_count(from);
>>>>> +        if (f2fs_overwrite_io(inode, iocb->ki_pos,
>>>>> +                        iov_iter_count(from)))
>>>>> +            goto write;
>>>>
>>>> This calls f2fs_map_blocks() which can be duplicate, if it's not the overwirte
>>>> case. Do we have other benefit?
>>>
>>> f2fs_overwrite_io() will break for append write case w/ below check:
>>>
>>>       if (pos + len > i_size_read(inode))
>>>           return false;
>>>
>>> I guess we may only suffer double f2fs_map_blocks() for write hole
>>> case, e.g. truncate to large size & write inside the filesize. For
>>> this case, how about adding a condition to allow double f2fs_map_blocks()
>>> only if write size is smaller than a threshold?
> 
> I still don't see the benefit much to do double f2fs_map_blocks. What is the
> problem here?

There is potential hangtask happened during swapfile's writeback:

- loop_kthread_worker_fn
  - kthread_worker_fn
   - loop_queue_work
    - lo_rw_aio
     - f2fs_file_write_iter
      - f2fs_preallocate_blocks
       - f2fs_map_blocks
        - down_read
         - rwsem_down_read_slowpath
          - schedule

I try to mitigate such issue by preallocating swapfile's block address and
avoid f2fs_do_map_lock() as much as possible in swapfile's writeback path...

Thanks,

> 
>>>
>>> Thanks,
>>>
>>>>
>>>>> +
>>>>>            err = f2fs_preallocate_blocks(iocb, from);
>>>>>            if (err) {
>>>>>    out_err:
>>>>> -- 
>>>>> 2.32.0
>>>
>>>
>>> _______________________________________________
>>> Linux-f2fs-devel mailing list
>>> Linux-f2fs-devel@lists.sourceforge.net
>>> https://apc01.safelinks.protection.outlook.com/?url=https%3A%2F%2Flists.sourceforge.net%2Flists%2Flistinfo%2Flinux-f2fs-devel&amp;data=04%7C01%7Cchao.yu%40oppo.com%7C421c06812eba4f922b0908d982dcdcc5%7Cf1905eb1c35341c5951662b4a54b5ee6%7C0%7C0%7C637684707374940190%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&amp;sdata=u22eEWDAPaAZCyISyjTUOtQDLDuyKxTnNCI3eSwwWro%3D&amp;reserved=0

Re: [f2fs-dev] [PATCH] f2fs: skip f2fs_preallocate_blocks() for overwrite case

[Chao Yu]

Ping,

On 2021/10/30 11:02, Chao Yu wrote:
> On 2021/10/30 1:43, Jaegeuk Kim wrote:
>> On 10/29, Chao Yu wrote:
>>> Ping,
>>>
>>> On 2021/9/29 8:05, Chao Yu wrote:
>>>> On 2021/9/29 3:08, Jaegeuk Kim wrote:
>>>>> On 09/28, Chao Yu wrote:
>>>>>> In f2fs_file_write_iter(), let's use f2fs_overwrite_io() to
>>>>>> check whethere it is overwrite case, for such case, we can skip
>>>>>> f2fs_preallocate_blocks() in order to avoid f2fs_do_map_lock(),
>>>>>> which may be blocked by checkpoint() potentially.
>>>>>>
>>>>>> Signed-off-by: Chao Yu <chao@kernel.org>
>>>>>> ---
>>>>>>    fs/f2fs/file.c | 4 ++++
>>>>>>    1 file changed, 4 insertions(+)
>>>>>>
>>>>>> diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
>>>>>> index 13deae03df06..51fecb2f4db5 100644
>>>>>> --- a/fs/f2fs/file.c
>>>>>> +++ b/fs/f2fs/file.c
>>>>>> @@ -4321,6 +4321,10 @@ static ssize_t f2fs_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
>>>>>>            preallocated = true;
>>>>>>            target_size = iocb->ki_pos + iov_iter_count(from);
>>>>>> +        if (f2fs_overwrite_io(inode, iocb->ki_pos,
>>>>>> +                        iov_iter_count(from)))
>>>>>> +            goto write;
>>>>>
>>>>> This calls f2fs_map_blocks() which can be duplicate, if it's not the overwirte
>>>>> case. Do we have other benefit?
>>>>
>>>> f2fs_overwrite_io() will break for append write case w/ below check:
>>>>
>>>>       if (pos + len > i_size_read(inode))
>>>>           return false;
>>>>
>>>> I guess we may only suffer double f2fs_map_blocks() for write hole
>>>> case, e.g. truncate to large size & write inside the filesize. For
>>>> this case, how about adding a condition to allow double f2fs_map_blocks()
>>>> only if write size is smaller than a threshold?
>>
>> I still don't see the benefit much to do double f2fs_map_blocks. What is the
>> problem here?
> 
> There is potential hangtask happened during swapfile's writeback:
> 
> - loop_kthread_worker_fn
>   - kthread_worker_fn
>    - loop_queue_work
>     - lo_rw_aio
>      - f2fs_file_write_iter
>       - f2fs_preallocate_blocks
>        - f2fs_map_blocks
>         - down_read
>          - rwsem_down_read_slowpath
>           - schedule
> 
> I try to mitigate such issue by preallocating swapfile's block address and
> avoid f2fs_do_map_lock() as much as possible in swapfile's writeback path...
> 
> Thanks,
> 
>>
>>>>
>>>> Thanks,
>>>>
>>>>>
>>>>>> +
>>>>>>            err = f2fs_preallocate_blocks(iocb, from);
>>>>>>            if (err) {
>>>>>>    out_err:
>>>>>> -- 
>>>>>> 2.32.0
>>>>
>>>>
>>>> _______________________________________________
>>>> Linux-f2fs-devel mailing list
>>>> Linux-f2fs-devel@lists.sourceforge.net
>>>> https://apc01.safelinks.protection.outlook.com/?url=https%3A%2F%2Flists.sourceforge.net%2Flists%2Flistinfo%2Flinux-f2fs-devel&amp;data=04%7C01%7Cchao.yu%40oppo.com%7Cbb41006c3f6d4e4d600a08d99b51cbcd%7Cf1905eb1c35341c5951662b4a54b5ee6%7C0%7C0%7C637711597895400286%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000&amp;sdata=%2BlEAXWLpV5wGX2hL0Wj5p2qX0AqfUFI05Qiqdp8PK8g%3D&amp;reserved=0
> 
> 
> _______________________________________________
> 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: [f2fs-dev] [PATCH] f2fs: skip f2fs_preallocate_blocks() for overwrite case

[Chao Yu]

Ping,

On 2021/10/30 11:02, Chao Yu wrote:
> On 2021/10/30 1:43, Jaegeuk Kim wrote:
>> On 10/29, Chao Yu wrote:
>>> Ping,
>>>
>>> On 2021/9/29 8:05, Chao Yu wrote:
>>>> On 2021/9/29 3:08, Jaegeuk Kim wrote:
>>>>> On 09/28, Chao Yu wrote:
>>>>>> In f2fs_file_write_iter(), let's use f2fs_overwrite_io() to
>>>>>> check whethere it is overwrite case, for such case, we can skip
>>>>>> f2fs_preallocate_blocks() in order to avoid f2fs_do_map_lock(),
>>>>>> which may be blocked by checkpoint() potentially.
>>>>>>
>>>>>> Signed-off-by: Chao Yu <chao@kernel.org>
>>>>>> ---
>>>>>>    fs/f2fs/file.c | 4 ++++
>>>>>>    1 file changed, 4 insertions(+)
>>>>>>
>>>>>> diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
>>>>>> index 13deae03df06..51fecb2f4db5 100644
>>>>>> --- a/fs/f2fs/file.c
>>>>>> +++ b/fs/f2fs/file.c
>>>>>> @@ -4321,6 +4321,10 @@ static ssize_t f2fs_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
>>>>>>            preallocated = true;
>>>>>>            target_size = iocb->ki_pos + iov_iter_count(from);
>>>>>> +        if (f2fs_overwrite_io(inode, iocb->ki_pos,
>>>>>> +                        iov_iter_count(from)))
>>>>>> +            goto write;
>>>>>
>>>>> This calls f2fs_map_blocks() which can be duplicate, if it's not the overwirte
>>>>> case. Do we have other benefit?
>>>>
>>>> f2fs_overwrite_io() will break for append write case w/ below check:
>>>>
>>>>       if (pos + len > i_size_read(inode))
>>>>           return false;
>>>>
>>>> I guess we may only suffer double f2fs_map_blocks() for write hole
>>>> case, e.g. truncate to large size & write inside the filesize. For
>>>> this case, how about adding a condition to allow double f2fs_map_blocks()
>>>> only if write size is smaller than a threshold?
>>
>> I still don't see the benefit much to do double f2fs_map_blocks. What is the
>> problem here?
> 
> There is potential hangtask happened during swapfile's writeback:
> 
> - loop_kthread_worker_fn
>   - kthread_worker_fn
>    - loop_queue_work
>     - lo_rw_aio
>      - f2fs_file_write_iter
>       - f2fs_preallocate_blocks
>        - f2fs_map_blocks
>         - down_read
>          - rwsem_down_read_slowpath
>           - schedule
> 
> I try to mitigate such issue by preallocating swapfile's block address and
> avoid f2fs_do_map_lock() as much as possible in swapfile's writeback path...
> 
> Thanks,
> 
>>
>>>>
>>>> Thanks,
>>>>
>>>>>
>>>>>> +
>>>>>>            err = f2fs_preallocate_blocks(iocb, from);
>>>>>>            if (err) {
>>>>>>    out_err:
>>>>>> -- 
>>>>>> 2.32.0
>>>>
>>>>
>>>> _______________________________________________
>>>> Linux-f2fs-devel mailing list
>>>> Linux-f2fs-devel@lists.sourceforge.net
>>>> https://apc01.safelinks.protection.outlook.com/?url=https%3A%2F%2Flists.sourceforge.net%2Flists%2Flistinfo%2Flinux-f2fs-devel&amp;data=04%7C01%7Cchao.yu%40oppo.com%7Cbb41006c3f6d4e4d600a08d99b51cbcd%7Cf1905eb1c35341c5951662b4a54b5ee6%7C0%7C0%7C637711597895400286%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000&amp;sdata=%2BlEAXWLpV5wGX2hL0Wj5p2qX0AqfUFI05Qiqdp8PK8g%3D&amp;reserved=0
> 
> 
> _______________________________________________
> Linux-f2fs-devel mailing list
> Linux-f2fs-devel@lists.sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel

Re: [f2fs-dev] [PATCH] f2fs: skip f2fs_preallocate_blocks() for overwrite case

[Jaegeuk Kim]

On 12/12, Chao Yu wrote:
> Ping,
> 
> On 2021/10/30 11:02, Chao Yu wrote:
> > On 2021/10/30 1:43, Jaegeuk Kim wrote:
> > > On 10/29, Chao Yu wrote:
> > > > Ping,
> > > > 
> > > > On 2021/9/29 8:05, Chao Yu wrote:
> > > > > On 2021/9/29 3:08, Jaegeuk Kim wrote:
> > > > > > On 09/28, Chao Yu wrote:
> > > > > > > In f2fs_file_write_iter(), let's use f2fs_overwrite_io() to
> > > > > > > check whethere it is overwrite case, for such case, we can skip
> > > > > > > f2fs_preallocate_blocks() in order to avoid f2fs_do_map_lock(),
> > > > > > > which may be blocked by checkpoint() potentially.
> > > > > > > 
> > > > > > > Signed-off-by: Chao Yu <chao@kernel.org>
> > > > > > > ---
> > > > > > >    fs/f2fs/file.c | 4 ++++
> > > > > > >    1 file changed, 4 insertions(+)
> > > > > > > 
> > > > > > > diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
> > > > > > > index 13deae03df06..51fecb2f4db5 100644
> > > > > > > --- a/fs/f2fs/file.c
> > > > > > > +++ b/fs/f2fs/file.c
> > > > > > > @@ -4321,6 +4321,10 @@ static ssize_t f2fs_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
> > > > > > >            preallocated = true;
> > > > > > >            target_size = iocb->ki_pos + iov_iter_count(from);
> > > > > > > +        if (f2fs_overwrite_io(inode, iocb->ki_pos,
> > > > > > > +                        iov_iter_count(from)))
> > > > > > > +            goto write;
> > > > > > 
> > > > > > This calls f2fs_map_blocks() which can be duplicate, if it's not the overwirte
> > > > > > case. Do we have other benefit?
> > > > > 
> > > > > f2fs_overwrite_io() will break for append write case w/ below check:
> > > > > 
> > > > >       if (pos + len > i_size_read(inode))
> > > > >           return false;
> > > > > 
> > > > > I guess we may only suffer double f2fs_map_blocks() for write hole
> > > > > case, e.g. truncate to large size & write inside the filesize. For
> > > > > this case, how about adding a condition to allow double f2fs_map_blocks()
> > > > > only if write size is smaller than a threshold?
> > > 
> > > I still don't see the benefit much to do double f2fs_map_blocks. What is the
> > > problem here?
> > 
> > There is potential hangtask happened during swapfile's writeback:
> > 
> > - loop_kthread_worker_fn
> >   - kthread_worker_fn
> >    - loop_queue_work
> >     - lo_rw_aio
> >      - f2fs_file_write_iter
> >       - f2fs_preallocate_blocks
> >        - f2fs_map_blocks
> >         - down_read
> >          - rwsem_down_read_slowpath
> >           - schedule
> > 
> > I try to mitigate such issue by preallocating swapfile's block address and
> > avoid f2fs_do_map_lock() as much as possible in swapfile's writeback path...

How about checking i_blocks and i_size instead of checking the entire map?

> > 
> > Thanks,
> > 
> > > 
> > > > > 
> > > > > Thanks,
> > > > > 
> > > > > > 
> > > > > > > +
> > > > > > >            err = f2fs_preallocate_blocks(iocb, from);
> > > > > > >            if (err) {
> > > > > > >    out_err:
> > > > > > > -- 
> > > > > > > 2.32.0
> > > > > 
> > > > > 
> > > > > _______________________________________________
> > > > > Linux-f2fs-devel mailing list
> > > > > Linux-f2fs-devel@lists.sourceforge.net
> > > > > https://apc01.safelinks.protection.outlook.com/?url=https%3A%2F%2Flists.sourceforge.net%2Flists%2Flistinfo%2Flinux-f2fs-devel&amp;data=04%7C01%7Cchao.yu%40oppo.com%7Cbb41006c3f6d4e4d600a08d99b51cbcd%7Cf1905eb1c35341c5951662b4a54b5ee6%7C0%7C0%7C637711597895400286%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000&amp;sdata=%2BlEAXWLpV5wGX2hL0Wj5p2qX0AqfUFI05Qiqdp8PK8g%3D&amp;reserved=0
> > 
> > 
> > _______________________________________________
> > Linux-f2fs-devel mailing list
> > Linux-f2fs-devel@lists.sourceforge.net
> > https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel

Re: [f2fs-dev] [PATCH] f2fs: skip f2fs_preallocate_blocks() for overwrite case

[Jaegeuk Kim]

On 12/12, Chao Yu wrote:
> Ping,
> 
> On 2021/10/30 11:02, Chao Yu wrote:
> > On 2021/10/30 1:43, Jaegeuk Kim wrote:
> > > On 10/29, Chao Yu wrote:
> > > > Ping,
> > > > 
> > > > On 2021/9/29 8:05, Chao Yu wrote:
> > > > > On 2021/9/29 3:08, Jaegeuk Kim wrote:
> > > > > > On 09/28, Chao Yu wrote:
> > > > > > > In f2fs_file_write_iter(), let's use f2fs_overwrite_io() to
> > > > > > > check whethere it is overwrite case, for such case, we can skip
> > > > > > > f2fs_preallocate_blocks() in order to avoid f2fs_do_map_lock(),
> > > > > > > which may be blocked by checkpoint() potentially.
> > > > > > > 
> > > > > > > Signed-off-by: Chao Yu <chao@kernel.org>
> > > > > > > ---
> > > > > > >    fs/f2fs/file.c | 4 ++++
> > > > > > >    1 file changed, 4 insertions(+)
> > > > > > > 
> > > > > > > diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
> > > > > > > index 13deae03df06..51fecb2f4db5 100644
> > > > > > > --- a/fs/f2fs/file.c
> > > > > > > +++ b/fs/f2fs/file.c
> > > > > > > @@ -4321,6 +4321,10 @@ static ssize_t f2fs_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
> > > > > > >            preallocated = true;
> > > > > > >            target_size = iocb->ki_pos + iov_iter_count(from);
> > > > > > > +        if (f2fs_overwrite_io(inode, iocb->ki_pos,
> > > > > > > +                        iov_iter_count(from)))
> > > > > > > +            goto write;
> > > > > > 
> > > > > > This calls f2fs_map_blocks() which can be duplicate, if it's not the overwirte
> > > > > > case. Do we have other benefit?
> > > > > 
> > > > > f2fs_overwrite_io() will break for append write case w/ below check:
> > > > > 
> > > > >       if (pos + len > i_size_read(inode))
> > > > >           return false;
> > > > > 
> > > > > I guess we may only suffer double f2fs_map_blocks() for write hole
> > > > > case, e.g. truncate to large size & write inside the filesize. For
> > > > > this case, how about adding a condition to allow double f2fs_map_blocks()
> > > > > only if write size is smaller than a threshold?
> > > 
> > > I still don't see the benefit much to do double f2fs_map_blocks. What is the
> > > problem here?
> > 
> > There is potential hangtask happened during swapfile's writeback:
> > 
> > - loop_kthread_worker_fn
> >   - kthread_worker_fn
> >    - loop_queue_work
> >     - lo_rw_aio
> >      - f2fs_file_write_iter
> >       - f2fs_preallocate_blocks
> >        - f2fs_map_blocks
> >         - down_read
> >          - rwsem_down_read_slowpath
> >           - schedule
> > 
> > I try to mitigate such issue by preallocating swapfile's block address and
> > avoid f2fs_do_map_lock() as much as possible in swapfile's writeback path...

How about checking i_blocks and i_size instead of checking the entire map?

> > 
> > Thanks,
> > 
> > > 
> > > > > 
> > > > > Thanks,
> > > > > 
> > > > > > 
> > > > > > > +
> > > > > > >            err = f2fs_preallocate_blocks(iocb, from);
> > > > > > >            if (err) {
> > > > > > >    out_err:
> > > > > > > -- 
> > > > > > > 2.32.0
> > > > > 
> > > > > 
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> > 
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Re: [f2fs-dev] [PATCH] f2fs: skip f2fs_preallocate_blocks() for overwrite case

[Chao Yu]

On 2021/12/15 2:56, Jaegeuk Kim wrote:
> On 12/12, Chao Yu wrote:
>> Ping,
>>
>> On 2021/10/30 11:02, Chao Yu wrote:
>>> On 2021/10/30 1:43, Jaegeuk Kim wrote:
>>>> On 10/29, Chao Yu wrote:
>>>>> Ping,
>>>>>
>>>>> On 2021/9/29 8:05, Chao Yu wrote:
>>>>>> On 2021/9/29 3:08, Jaegeuk Kim wrote:
>>>>>>> On 09/28, Chao Yu wrote:
>>>>>>>> In f2fs_file_write_iter(), let's use f2fs_overwrite_io() to
>>>>>>>> check whethere it is overwrite case, for such case, we can skip
>>>>>>>> f2fs_preallocate_blocks() in order to avoid f2fs_do_map_lock(),
>>>>>>>> which may be blocked by checkpoint() potentially.
>>>>>>>>
>>>>>>>> Signed-off-by: Chao Yu <chao@kernel.org>
>>>>>>>> ---
>>>>>>>>     fs/f2fs/file.c | 4 ++++
>>>>>>>>     1 file changed, 4 insertions(+)
>>>>>>>>
>>>>>>>> diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
>>>>>>>> index 13deae03df06..51fecb2f4db5 100644
>>>>>>>> --- a/fs/f2fs/file.c
>>>>>>>> +++ b/fs/f2fs/file.c
>>>>>>>> @@ -4321,6 +4321,10 @@ static ssize_t f2fs_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
>>>>>>>>             preallocated = true;
>>>>>>>>             target_size = iocb->ki_pos + iov_iter_count(from);
>>>>>>>> +        if (f2fs_overwrite_io(inode, iocb->ki_pos,
>>>>>>>> +                        iov_iter_count(from)))
>>>>>>>> +            goto write;
>>>>>>>
>>>>>>> This calls f2fs_map_blocks() which can be duplicate, if it's not the overwirte
>>>>>>> case. Do we have other benefit?
>>>>>>
>>>>>> f2fs_overwrite_io() will break for append write case w/ below check:
>>>>>>
>>>>>>        if (pos + len > i_size_read(inode))
>>>>>>            return false;
>>>>>>
>>>>>> I guess we may only suffer double f2fs_map_blocks() for write hole
>>>>>> case, e.g. truncate to large size & write inside the filesize. For
>>>>>> this case, how about adding a condition to allow double f2fs_map_blocks()
>>>>>> only if write size is smaller than a threshold?
>>>>
>>>> I still don't see the benefit much to do double f2fs_map_blocks. What is the
>>>> problem here?
>>>
>>> There is potential hangtask happened during swapfile's writeback:
>>>
>>> - loop_kthread_worker_fn
>>>    - kthread_worker_fn
>>>     - loop_queue_work
>>>      - lo_rw_aio
>>>       - f2fs_file_write_iter
>>>        - f2fs_preallocate_blocks
>>>         - f2fs_map_blocks
>>>          - down_read
>>>           - rwsem_down_read_slowpath
>>>            - schedule
>>>
>>> I try to mitigate such issue by preallocating swapfile's block address and
>>> avoid f2fs_do_map_lock() as much as possible in swapfile's writeback path...
> 
> How about checking i_blocks and i_size instead of checking the entire map?

How about v2?

Thanks,

> 
>>>
>>> Thanks,
>>>
>>>>
>>>>>>
>>>>>> Thanks,
>>>>>>
>>>>>>>
>>>>>>>> +
>>>>>>>>             err = f2fs_preallocate_blocks(iocb, from);
>>>>>>>>             if (err) {
>>>>>>>>     out_err:
>>>>>>>> -- 
>>>>>>>> 2.32.0
>>>>>>
>>>>>>
>>>>>> _______________________________________________
>>>>>> Linux-f2fs-devel mailing list
>>>>>> Linux-f2fs-devel@lists.sourceforge.net
>>>>>> https://apc01.safelinks.protection.outlook.com/?url=https%3A%2F%2Flists.sourceforge.net%2Flists%2Flistinfo%2Flinux-f2fs-devel&amp;data=04%7C01%7Cchao.yu%40oppo.com%7Cbb41006c3f6d4e4d600a08d99b51cbcd%7Cf1905eb1c35341c5951662b4a54b5ee6%7C0%7C0%7C637711597895400286%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000&amp;sdata=%2BlEAXWLpV5wGX2hL0Wj5p2qX0AqfUFI05Qiqdp8PK8g%3D&amp;reserved=0
>>>
>>>
>>> _______________________________________________
>>> Linux-f2fs-devel mailing list
>>> Linux-f2fs-devel@lists.sourceforge.net
>>> https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel

Re: [f2fs-dev] [PATCH] f2fs: skip f2fs_preallocate_blocks() for overwrite case

[Chao Yu]

On 2021/12/15 2:56, Jaegeuk Kim wrote:
> On 12/12, Chao Yu wrote:
>> Ping,
>>
>> On 2021/10/30 11:02, Chao Yu wrote:
>>> On 2021/10/30 1:43, Jaegeuk Kim wrote:
>>>> On 10/29, Chao Yu wrote:
>>>>> Ping,
>>>>>
>>>>> On 2021/9/29 8:05, Chao Yu wrote:
>>>>>> On 2021/9/29 3:08, Jaegeuk Kim wrote:
>>>>>>> On 09/28, Chao Yu wrote:
>>>>>>>> In f2fs_file_write_iter(), let's use f2fs_overwrite_io() to
>>>>>>>> check whethere it is overwrite case, for such case, we can skip
>>>>>>>> f2fs_preallocate_blocks() in order to avoid f2fs_do_map_lock(),
>>>>>>>> which may be blocked by checkpoint() potentially.
>>>>>>>>
>>>>>>>> Signed-off-by: Chao Yu <chao@kernel.org>
>>>>>>>> ---
>>>>>>>>     fs/f2fs/file.c | 4 ++++
>>>>>>>>     1 file changed, 4 insertions(+)
>>>>>>>>
>>>>>>>> diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
>>>>>>>> index 13deae03df06..51fecb2f4db5 100644
>>>>>>>> --- a/fs/f2fs/file.c
>>>>>>>> +++ b/fs/f2fs/file.c
>>>>>>>> @@ -4321,6 +4321,10 @@ static ssize_t f2fs_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
>>>>>>>>             preallocated = true;
>>>>>>>>             target_size = iocb->ki_pos + iov_iter_count(from);
>>>>>>>> +        if (f2fs_overwrite_io(inode, iocb->ki_pos,
>>>>>>>> +                        iov_iter_count(from)))
>>>>>>>> +            goto write;
>>>>>>>
>>>>>>> This calls f2fs_map_blocks() which can be duplicate, if it's not the overwirte
>>>>>>> case. Do we have other benefit?
>>>>>>
>>>>>> f2fs_overwrite_io() will break for append write case w/ below check:
>>>>>>
>>>>>>        if (pos + len > i_size_read(inode))
>>>>>>            return false;
>>>>>>
>>>>>> I guess we may only suffer double f2fs_map_blocks() for write hole
>>>>>> case, e.g. truncate to large size & write inside the filesize. For
>>>>>> this case, how about adding a condition to allow double f2fs_map_blocks()
>>>>>> only if write size is smaller than a threshold?
>>>>
>>>> I still don't see the benefit much to do double f2fs_map_blocks. What is the
>>>> problem here?
>>>
>>> There is potential hangtask happened during swapfile's writeback:
>>>
>>> - loop_kthread_worker_fn
>>>    - kthread_worker_fn
>>>     - loop_queue_work
>>>      - lo_rw_aio
>>>       - f2fs_file_write_iter
>>>        - f2fs_preallocate_blocks
>>>         - f2fs_map_blocks
>>>          - down_read
>>>           - rwsem_down_read_slowpath
>>>            - schedule
>>>
>>> I try to mitigate such issue by preallocating swapfile's block address and
>>> avoid f2fs_do_map_lock() as much as possible in swapfile's writeback path...
> 
> How about checking i_blocks and i_size instead of checking the entire map?

How about v2?

Thanks,

> 
>>>
>>> Thanks,
>>>
>>>>
>>>>>>
>>>>>> Thanks,
>>>>>>
>>>>>>>
>>>>>>>> +
>>>>>>>>             err = f2fs_preallocate_blocks(iocb, from);
>>>>>>>>             if (err) {
>>>>>>>>     out_err:
>>>>>>>> -- 
>>>>>>>> 2.32.0
>>>>>>
>>>>>>
>>>>>> _______________________________________________
>>>>>> Linux-f2fs-devel mailing list
>>>>>> Linux-f2fs-devel@lists.sourceforge.net
>>>>>> https://apc01.safelinks.protection.outlook.com/?url=https%3A%2F%2Flists.sourceforge.net%2Flists%2Flistinfo%2Flinux-f2fs-devel&amp;data=04%7C01%7Cchao.yu%40oppo.com%7Cbb41006c3f6d4e4d600a08d99b51cbcd%7Cf1905eb1c35341c5951662b4a54b5ee6%7C0%7C0%7C637711597895400286%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000&amp;sdata=%2BlEAXWLpV5wGX2hL0Wj5p2qX0AqfUFI05Qiqdp8PK8g%3D&amp;reserved=0
>>>
>>>
>>> _______________________________________________
>>> Linux-f2fs-devel mailing list
>>> Linux-f2fs-devel@lists.sourceforge.net
>>> https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel


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