On 2019/9/1 15:17, Jaegeuk Kim wrote:
> On 08/31, Chao Yu wrote:
>> On 2019/2/19 16:15, Chao Yu wrote:
>>> @@ -1976,10 +2035,13 @@ static int __write_data_page(struct page *page,
>>> bool *submitted,
>>> }
>>>
>>> unlock_page(page);
>>> - if (!S_ISDIR(inode->i_mode) && !IS_NOQUOTA(inode))
>>> + if (!S_ISDIR(inode->i_mode) && !IS_NOQUOTA(inode)) {
>>> + f2fs_submit_ipu_bio(sbi, bio, page);
>>> f2fs_balance_fs(sbi, need_balance_fs);
>>> + }
>>
>> Above bio submission was added to avoid below deadlock:
>>
>> - __write_data_page
>> - f2fs_do_write_data_page
>> - set_page_writeback ---- set writeback flag
>> - f2fs_inplace_write_data
>> - f2fs_balance_fs
>> - f2fs_gc
>> - do_garbage_collect
>> - gc_data_segment
>> - move_data_page
>> - f2fs_wait_on_page_writeback
>> - wait_on_page_writeback --- wait writeback
>>
>> However, it breaks the merge of IPU IOs, to solve this issue, it looks we
>> need
>> to add global bio cache for such IPU merge case, then later
>> f2fs_wait_on_page_writeback can check whether writebacked page is cached or
>> not,
>> and do the submission if necessary.
>>
>> Jaegeuk, any thoughts?
>
> How about calling f2fs_submit_ipu_bio() when we need to do GC in the same
> context?
However it also could happen in race case:
Thread A Thread B
- __write_data_page (inode x, page y)
- f2fs_do_write_data_page
- set_page_writeback ---- set writeback flag in page y
- f2fs_inplace_write_data
- f2fs_balance_fs
- lock gc_mutex
- lock gc_mutex
- f2fs_gc
- do_garbage_collect
- gc_data_segment
- move_data_page
- f2fs_wait_on_page_writeback
- wait_on_page_writeback ---
wait writeback of page y
So it needs a global bio cache for merged IPU pages, how about adding a list to
link all ipu bios in struct f2fs_bio_info?
struct f2fs_bio_info {
....
struct list_head ipu_bio_list; /* track all ipu bio */
spinlock_t ipu_bio_lock; /* protect ipu bio list */
}
>
>>
>> Thanks,
> .
>
