Hi Jaegeuk,
On 2017/3/2 3:48, Jaegeuk Kim wrote:
> On 02/28, heyunlei wrote:
>> Hi Jaegeuk,
>>
>> On 2017/2/28 7:08, Jaegeuk Kim wrote:
>>> On 02/27, Yunlei He wrote:
>>>> This patch add a function to modify discard command if one segment
>>>> reuse before discard. Split this segment from multi-segments discard
>>>> range, and discard the left bigger range.
>>>
>>> Now MAX_DISCARD_BLOCKS() is set to section size, so there will be no
>>> multi-sections discard range. Am I missing some cases?
>>
>> I think MAX_DISCARD_BLOCKS() just limit small discard and fstrim, f2fs
>>
>> can still send multi-segments discard range if prefree segments is
>> continuous.
>
> Got it.
> Comments below.
>
>>>> Signed-off-by: Yunlei He <[email protected]>
>>>> ---
>>>> fs/f2fs/segment.c | 18 +++++++++++++++++-
>>>> 1 file changed, 17 insertions(+), 1 deletion(-)
>>>>
>>>> diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
>>>> index 9006d8e..5af736b 100644
>>>> --- a/fs/f2fs/segment.c
>>>> +++ b/fs/f2fs/segment.c
>>>> @@ -672,6 +672,22 @@ static void __remove_discard_cmd(struct f2fs_sb_info
>>>> *sbi, struct discard_cmd *d
>>>> kmem_cache_free(discard_cmd_slab, dc);
>>>> }
>>>>
>>>> +static void __modify_discard_cmd(struct f2fs_sb_info *sbi, struct
>>>> discard_cmd *dc, block_t blkaddr)
>
> How about modifying the name "modify" to "punch"?
>
>>>> +{
>>>> + block_t end_block = START_BLOCK(sbi, GET_SEGNO(sbi, blkaddr) + 1);
>>>> +
>>>> + if (dc->lstart + dc->len <= end_block) {
>>>> + __remove_discard_cmd(sbi, dc);
>>>> + return;
>>>> + }
>>>> +
>>>> + if (dc->lstart - blkaddr < dc->lstart + dc->len - end_block) {
>
> The blkaddr is larger than or equal to dc->lstart all the time, resulting in
> overflow?
Yes, here should be if (blkaddr - dc->lstart < dc->lstart + dc->len - end_block)
>
> Thanks,
>
>>>> + dc->lstart = end_block;
>>>> + dc->len -= (end_block - dc->lstart);
>>>> + } else
>>>> + dc->len = blkaddr - dc->lstart;
>>>> +}
>>>> +
>>>> /* This should be covered by global mutex, &sit_i->sentry_lock */
>>>> void f2fs_wait_discard_bio(struct f2fs_sb_info *sbi, block_t blkaddr)
>>>> {
>>>> @@ -699,7 +715,7 @@ void f2fs_wait_discard_bio(struct f2fs_sb_info *sbi,
>>>> block_t blkaddr)
>>>> if (dc->state == D_SUBMIT)
>>>> wait_for_completion_io(&dc->wait);
>>>> else
>>>> - __remove_discard_cmd(sbi, dc);
>>>> + __modify_discard_cmd(sbi, dc, blkaddr);
>>>> }
>>>> }
>>>> blk_finish_plug(&plug);
>>>> --
>>>> 2.10.1
>>>
>>> .
>>>
>
> .
>
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