Messages in this thread | | | Subject | Re: [f2fs-dev] [PATCH] f2fs: don't skip writeback of quota data | From | Chao Yu <> | Date | Thu, 16 Jul 2020 09:08:29 +0800 |
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On 2020/7/16 3:10, Jaegeuk Kim wrote: > On 07/14, Chao Yu wrote: >> On 2020/7/14 1:59, Jaegeuk Kim wrote: >>> On 07/10, Chao Yu wrote: >>>> On 2020/7/10 11:50, Jaegeuk Kim wrote: >>>>> On 07/10, Chao Yu wrote: >>>>>> On 2020/7/10 11:26, Jaegeuk Kim wrote: >>>>>>> On 07/10, Chao Yu wrote: >>>>>>>> On 2020/7/10 3:05, Jaegeuk Kim wrote: >>>>>>>>> On 07/09, Chao Yu wrote: >>>>>>>>>> On 2020/7/9 13:30, Jaegeuk Kim wrote: >>>>>>>>>>> It doesn't need to bypass flushing quota data in background. >>>>>>>>>> >>>>>>>>>> The condition is used to flush quota data in batch to avoid random >>>>>>>>>> small-sized udpate, did you hit any problem here? >>>>>>>>> >>>>>>>>> I suspect this causes fault injection test being stuck by waiting for inode >>>>>>>>> writeback completion. With this patch, it has been running w/o any issue so far. >>>>>>>>> I keep an eye on this. >>>>>>>> >>>>>>>> Hmmm.. so that this patch may not fix the root cause, and it may hiding the >>>>>>>> issue deeper. >>>>>>>> >>>>>>>> How about just keeping this patch in our private branch to let fault injection >>>>>>>> test not be stuck? until we find the root cause in upstream codes. >>>>>>> >>>>>>> Well, I don't think this hides something. When the issue happens, I saw inodes >>>>>>> being stuck due to writeback while only quota has some dirty data. At that time, >>>>>>> there was no dirty data page from other inodes. >>>>>> >>>>>> Okay, >>>>>> >>>>>>> >>>>>>> More specifically, I suspect __writeback_inodes_sb_nr() gives WB_SYNC_NONE and >>>>>>> waits for wb_wait_for_completion(). >>>>>> >>>>>> Did you record any callstack after the issue happened? >>>>> >>>>> I found this. >>>>> >>>>> [213389.297642] __schedule+0x2dd/0x780^M >>>>> [213389.299224] schedule+0x55/0xc0^M >>>>> [213389.300745] wb_wait_for_completion+0x56/0x90^M >>>>> [213389.302469] ? wait_woken+0x80/0x80^M >>>>> [213389.303997] __writeback_inodes_sb_nr+0xa8/0xd0^M >>>>> [213389.305760] writeback_inodes_sb+0x4b/0x60^M >>>>> [213389.307439] sync_filesystem+0x2e/0xa0^M >>>>> [213389.308999] generic_shutdown_super+0x27/0x110^M >>>>> [213389.310738] kill_block_super+0x27/0x50^M >>>>> [213389.312327] kill_f2fs_super+0x76/0xe0 [f2fs]^M >>>>> [213389.314014] deactivate_locked_super+0x3b/0x80^M >>>>> [213389.315692] deactivate_super+0x3e/0x50^M >>>>> [213389.317226] cleanup_mnt+0x109/0x160^M >>>>> [213389.318718] __cleanup_mnt+0x12/0x20^M >>>>> [213389.320177] task_work_run+0x70/0xb0^M >>>>> [213389.321609] exit_to_usermode_loop+0x131/0x160^M >>>>> [213389.323306] do_syscall_64+0x170/0x1b0^M >>>>> [213389.324762] entry_SYSCALL_64_after_hwframe+0x44/0xa9^M >>>>> [213389.326477] RIP: 0033:0x7fc4b5e6a35b^M >>>> >>>> Does this only happen during umount? If so, will below change help? >>>> >>>> if ((S_ISDIR(inode->i_mode) || IS_NOQUOTA(inode)) && >>>> + !is_sbi_flag_set(sbi, SBI_IS_CLOSE) && >>>> wbc->sync_mode == WB_SYNC_NONE && >>>> get_dirty_pages(inode) < nr_pages_to_skip(sbi, DATA) && >>>> f2fs_available_free_memory(sbi, DIRTY_DENTS)) >>>> goto skip_write; >>> >>> Hmm, this doesn't work. The writeback was called before put_super? >> >> Oops, still be confused about this issue. :( > > Huam, I hit the problem with the patch. > I need to return back and think in other way. :(
Still quota data was left? what about dentry?
Thanks,
> >> >> Thanks, >> >>> I'll try the original patch one more time. >>> >>>> >>>>> >>>>>> >>>>>> Still I'm confused that why directory's data written could be skipped, but >>>>>> quota's data couldn't, what's the difference? >>>>> >>>>> I suspect different blocking timing from cp_error between quota and dentry. >>>>> e.g., we block dir operations right after cp_error, while quota can make >>>> >>>> No guarantee that there is no dirty dentry being created after >>>> cp_error, right? >>>> >>>> e.g. >>>> >>>> Thread A Thread B >>>> - f2fs_create >>>> - bypass f2fs_cp_error >>>> - set cp_error >>>> - create dirty dentry >>>> >>>> BTW, do you know what __writeback_inodes_sb_nr is waiting for? >>>> >>>>> dirty pages in more fine granularity. >>>>> >>>>>> >>>>>>> >>>>>>>> >>>>>>>> Thanks, >>>>>>>> >>>>>>>>> >>>>>>>>> Thanks, >>>>>>>>> >>>>>>>>>> >>>>>>>>>> Thanks, >>>>>>>>>> >>>>>>>>>>> >>>>>>>>>>> Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org> >>>>>>>>>>> --- >>>>>>>>>>> fs/f2fs/data.c | 2 +- >>>>>>>>>>> 1 file changed, 1 insertion(+), 1 deletion(-) >>>>>>>>>>> >>>>>>>>>>> diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c >>>>>>>>>>> index 44645f4f914b6..72e8b50e588c1 100644 >>>>>>>>>>> --- a/fs/f2fs/data.c >>>>>>>>>>> +++ b/fs/f2fs/data.c >>>>>>>>>>> @@ -3148,7 +3148,7 @@ static int __f2fs_write_data_pages(struct address_space *mapping, >>>>>>>>>>> if (unlikely(is_sbi_flag_set(sbi, SBI_POR_DOING))) >>>>>>>>>>> goto skip_write; >>>>>>>>>>> >>>>>>>>>>> - if ((S_ISDIR(inode->i_mode) || IS_NOQUOTA(inode)) && >>>>>>>>>>> + if (S_ISDIR(inode->i_mode) && >>>>>>>>>>> wbc->sync_mode == WB_SYNC_NONE && >>>>>>>>>>> get_dirty_pages(inode) < nr_pages_to_skip(sbi, DATA) && >>>>>>>>>>> f2fs_available_free_memory(sbi, DIRTY_DENTS)) >>>>>>>>>>> >>>>>>>>> . >>>>>>>>> >>>>>>> . >>>>>>> >>>>> . >>>>> >>> . >>> > . >
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