Re: [f2fs-dev] [PATCH v2] f2fs: add iostat latency tracking for direct IO

[liujinbao1 <jinbaoliu365@gmail.com>]

在 2026/5/9 17:20, Chao Yu 写道:
> On 5/8/26 21:59, liujinbao1 wrote:
>> From: liujinbao1 <liujinbao1@xiaomi.com>
>>
>> F2FS did not collect iostat latency for direct IO reads and writes,
>> hook iomap_dio_ops.submit_io to bind an iostat context and record the
>> submission timestamp. Replace bi_end_io with f2fs_dio_end_bio() to
>> collect IO latency on completion before calling back to the original
>> iomap_dio_bio_end_io(), to add iostat latency tracking support for
>> F2FS DIO.
>>
>> Signed-off-by: shengyong1 <shengyong1@xiaomi.com>
>> Signed-off-by: liujinbao1 <liujinbao1@xiaomi.com>
>> ---
>> v2:
>> - add f2fs_dio_iostat_start() to avoid duplicated code
>> and CONFIG_F2FS_IOSTAT guard
>> ---
>>   fs/f2fs/file.c   | 35 +++++++++++++++++++++++++++++++++++
>>   fs/f2fs/iostat.c |  2 +-
>>   2 files changed, 36 insertions(+), 1 deletion(-)
>>
>> diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
>> index 091a9db29228..d35e3cf158bf 100644
>> --- a/fs/f2fs/file.c
>> +++ b/fs/f2fs/file.c
>> @@ -4790,6 +4790,30 @@ static bool f2fs_should_use_dio(struct inode 
>> *inode, struct kiocb *iocb,
>>       return true;
>>   }
>>   +#ifdef CONFIG_F2FS_IOSTAT
>> +static void f2fs_dio_end_bio(struct bio *bio)
>> +{
>> +    struct bio_iostat_ctx *iostat_ctx = bio->bi_private;
>> +    void *orig_bi_private = iostat_ctx->post_read_ctx;
>> +
>> +    iostat_update_and_unbind_ctx(bio);
>> +    bio->bi_private = orig_bi_private;
>> +    iomap_dio_bio_end_io(bio);
>> +}
>> +
>> +static void f2fs_dio_iostat_start(struct f2fs_sb_info *sbi, struct 
>> bio *bio)
>> +{
>> +    void *bi_private = bio->bi_private;
>> +
>> +    iostat_alloc_and_bind_ctx(sbi, bio, bi_private);
>> +    iostat_update_submit_ctx(bio, DATA);
>> +    bio->bi_end_io = f2fs_dio_end_bio;
>> +}
>> +#else
>> +static inline void f2fs_dio_iostat_start(struct f2fs_sb_info *sbi,
>> +                     struct bio *bio) {}
>> +#endif
>> +
>>   static int f2fs_dio_read_end_io(struct kiocb *iocb, ssize_t size, 
>> int error,
>>                   unsigned int flags)
>>   {
>> @@ -4802,8 +4826,18 @@ static int f2fs_dio_read_end_io(struct kiocb 
>> *iocb, ssize_t size, int error,
>>       return 0;
>>   }
>>   +static void f2fs_dio_read_submit_io(const struct iomap_iter *iter,
>> +                    struct bio *bio, loff_t file_offset)
>> +{
>> +    struct f2fs_sb_info *sbi = F2FS_I_SB(iter->inode);
>> +
>> +    f2fs_dio_iostat_start(sbi, bio);
>> +    blk_crypto_submit_bio(bio);
>> +}
>> +
>>   static const struct iomap_dio_ops f2fs_iomap_dio_read_ops = {
>>       .end_io = f2fs_dio_read_end_io,
>> +    .submit_io = f2fs_dio_read_submit_io,
>>   };
>>     static ssize_t f2fs_dio_read_iter(struct kiocb *iocb, struct 
>> iov_iter *to)
>> @@ -5082,6 +5116,7 @@ static void f2fs_dio_write_submit_io(const 
>> struct iomap_iter *iter,
>>       enum temp_type temp = f2fs_get_segment_temp(sbi, type);
>>         bio->bi_write_hint = f2fs_io_type_to_rw_hint(sbi, DATA, temp);
>> +    f2fs_dio_iostat_start(sbi, bio);
>>       blk_crypto_submit_bio(bio);
>>   }
>>   diff --git a/fs/f2fs/iostat.c b/fs/f2fs/iostat.c
>> index ae265e3e9b2c..232fdec036c1 100644
>> --- a/fs/f2fs/iostat.c
>> +++ b/fs/f2fs/iostat.c
>> @@ -254,7 +254,7 @@ static inline void __update_iostat_latency(struct 
>> bio_iostat_ctx *iostat_ctx,
>>       struct iostat_lat_info *io_lat = sbi->iostat_io_lat;
>>       unsigned long flags;
>>   -    if (!sbi->iostat_enable)
>> +    if (!sbi->iostat_enable || iostat_ctx->submit_ts == 0)
>
> Which path we will see zeroed .submit_ts?
>
> Thanks,
>
After careful investigation, this scenario should not exist. I will 
modify the code.

thanks

>>           return;
>>         ts_diff = jiffies - iostat_ctx->submit_ts;
>


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