Re: [PATCH 2/4] mpage: mpage_readpages() should submit IO as read-ahead

[Jens Axboe <axboe@kernel.dk>]

On 6/21/18 1:32 PM, Jaegeuk Kim wrote:
> On 06/21, Jens Axboe wrote:
>> On 6/21/18 12:47 PM, Jaegeuk Kim wrote:
>>> On 06/20, Jens Axboe wrote:
>>>> a_ops->readpages() is only ever used for read-ahead, yet we don't
>>>> flag the IO being submitted as such. Fix that up. Any file system
>>>> that uses mpage_readpages() as its ->readpages() implementation
>>>> will now get this right.
>>>>
>>>> Since we're passing in whether the IO is read-ahead or not, we
>>>> don't need to pass in the 'gfp' separately, as it is dependent
>>>> on the IO being read-ahead. Kill off that member.
>>>>
>>>> Add some documentation notes on ->readpages() being purely for
>>>> read-ahead.
>>>>
>>>> Signed-off-by: Jens Axboe <axboe@kernel.dk>
>>>> ---
>>>>  fs/f2fs/data.c     |  5 +++++
>>>>  fs/mpage.c         | 29 +++++++++++++++++++----------
>>>>  include/linux/fs.h |  4 ++++
>>>>  3 files changed, 28 insertions(+), 10 deletions(-)
>>>>
>>>> diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
>>>> index 8f931d699287..b7c9b58acf3e 100644
>>>> --- a/fs/f2fs/data.c
>>>> +++ b/fs/f2fs/data.c
>>>> @@ -1421,6 +1421,11 @@ int f2fs_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
>>>>  /*
>>>>   * This function was originally taken from fs/mpage.c, and customized for f2fs.
>>>>   * Major change was from block_size == page_size in f2fs by default.
>>>> + *
>>>> + * Note that the aops->readpages() function is ONLY used for read-ahead. If
>>>> + * this function ever deviates from doing just read-ahead, it should either
>>>> + * use ->readpage() or do the necessary surgery to decouple ->readpages()
>>>> + * readom read-ahead.
>>>>   */
>>>>  static int f2fs_mpage_readpages(struct address_space *mapping,
>>>>  			struct list_head *pages, struct page *page,
>>>
>>> Hi Jens,
>>>
>>> Could you please consider the below change to address your concern?
>>
>> Looks good to me.
> 
> Let me add this change in f2fs tree.

Thanks!

-- 
Jens Axboe