Messages in this thread | | | Date | Fri, 4 Feb 2022 17:10:53 +0800 | Subject | Re: [f2fs-dev] [PATCH] f2fs: skip f2fs_preallocate_blocks() for overwrite case | From | Chao Yu <> |
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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&data=04%7C01%7Cchao.yu%40oppo.com%7Cbb41006c3f6d4e4d600a08d99b51cbcd%7Cf1905eb1c35341c5951662b4a54b5ee6%7C0%7C0%7C637711597895400286%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000&sdata=%2BlEAXWLpV5wGX2hL0Wj5p2qX0AqfUFI05Qiqdp8PK8g%3D&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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