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SubjectRe: [f2fs-dev] [PATCH v3] f2fs: avoid inifinite loop to wait for flushing node pages at cp_error
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On 2020/5/28 4:56, Jaegeuk Kim wrote:
> On 05/27, Chao Yu wrote:
>> On 2020/5/26 9:56, Jaegeuk Kim wrote:
>>> On 05/26, Chao Yu wrote:
>>>> On 2020/5/26 9:11, Chao Yu wrote:
>>>>> On 2020/5/25 23:06, Jaegeuk Kim wrote:
>>>>>> On 05/25, Chao Yu wrote:
>>>>>>> On 2020/5/25 11:56, Jaegeuk Kim wrote:
>>>>>>>> Shutdown test is somtimes hung, since it keeps trying to flush dirty node pages
>>
>> 71.07% 0.01% kworker/u256:1+ [kernel.kallsyms] [k] wb_writeback
>> |
>> --71.06%--wb_writeback
>> |
>> |--68.96%--__writeback_inodes_wb
>> | |
>> | --68.95%--writeback_sb_inodes
>> | |
>> | |--65.08%--__writeback_single_inode
>> | | |
>> | | --64.35%--do_writepages
>> | | |
>> | | |--59.83%--f2fs_write_node_pages
>> | | | |
>> | | | --59.74%--f2fs_sync_node_pages
>> | | | |
>> | | | |--27.91%--pagevec_lookup_range_tag
>> | | | | |
>> | | | | --27.90%--find_get_pages_range_tag
>>
>> Before umount, kworker will always hold one core, that looks not reasonable,
>> to avoid that, could we just allow node write, since it's out-place-update,
>> and cp is not allowed, we don't need to worry about its effect on data on
>> previous checkpoint, and it can decrease memory footprint cost by node pages.
>
> It can cause some roll-forward recovery?

Yup, recovery should be considered,

Later fsync() will fail due to:

int f2fs_sync_file(struct file *file, loff_t start, loff_t end, int datasync)
{
if (unlikely(f2fs_cp_error(F2FS_I_SB(file_inode(file)))))
return -EIO;


And we need to adjust f2fs_fsync_node_pages() to handle in-process fsyncing node
pages as well:

if (f2fs_cp_error()) {
set_fsync_mark(page, 0);
set_dentry_mark(page, 0);
if (atomic) {
unlock & put page;
ret = -EIO;
break;
}
}

ret = __write_node_page();

Thanks,

>
>>
>> Thanks,
>>
>>>>>>>
>>>>>>> IMO, for umount case, we should drop dirty reference and dirty pages on meta/data
>>>>>>> pages like we change for node pages to avoid potential dead loop...
>>>>>>
>>>>>> I believe we're doing for them. :P
>>>>>
>>>>> Actually, I mean do we need to drop dirty meta/data pages explicitly as below:
>>>>>
>>>>> diff --git a/fs/f2fs/checkpoint.c b/fs/f2fs/checkpoint.c
>>>>> index 3dc3ac6fe143..4c08fd0a680a 100644
>>>>> --- a/fs/f2fs/checkpoint.c
>>>>> +++ b/fs/f2fs/checkpoint.c
>>>>> @@ -299,8 +299,15 @@ static int __f2fs_write_meta_page(struct page *page,
>>>>>
>>>>> trace_f2fs_writepage(page, META);
>>>>>
>>>>> - if (unlikely(f2fs_cp_error(sbi)))
>>>>> + if (unlikely(f2fs_cp_error(sbi))) {
>>>>> + if (is_sbi_flag_set(sbi, SBI_IS_CLOSE)) {
>>>>> + ClearPageUptodate(page);
>>>>> + dec_page_count(sbi, F2FS_DIRTY_META);
>>>>> + unlock_page(page);
>>>>> + return 0;
>>>>> + }
>>>>> goto redirty_out;
>>>>> + }
>>>>> if (unlikely(is_sbi_flag_set(sbi, SBI_POR_DOING)))
>>>>> goto redirty_out;
>>>>> if (wbc->for_reclaim && page->index < GET_SUM_BLOCK(sbi, 0))
>>>>> diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
>>>>> index 48a622b95b76..94b342802513 100644
>>>>> --- a/fs/f2fs/data.c
>>>>> +++ b/fs/f2fs/data.c
>>>>> @@ -2682,6 +2682,12 @@ int f2fs_write_single_data_page(struct page *page, int *submitted,
>>>>>
>>>>> /* we should bypass data pages to proceed the kworkder jobs */
>>>>> if (unlikely(f2fs_cp_error(sbi))) {
>>>>> + if (is_sbi_flag_set(sbi, SBI_IS_CLOSE)) {
>>>>> + ClearPageUptodate(page);
>>>>> + inode_dec_dirty_pages(inode);
>>>>> + unlock_page(page);
>>>>> + return 0;
>>>>> + }
>>>>
>>>> Oh, I notice previously, we will drop non-directory inode's dirty pages directly,
>>>> however, during umount, we'd better drop directory inode's dirty pages as well, right?
>>>
>>> Hmm, I remember I dropped them before. Need to double check.
>>>
>>>>
>>>>> mapping_set_error(page->mapping, -EIO);
>>>>> /*
>>>>> * don't drop any dirty dentry pages for keeping lastest
>>>>>
>>>>>>
>>>>>>>
>>>>>>> Thanks,
>>>>>>>
>>>>>>>> in an inifinite loop. Let's drop dirty pages at umount in that case.
>>>>>>>>
>>>>>>>> Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
>>>>>>>> ---
>>>>>>>> v3:
>>>>>>>> - fix wrong unlock
>>>>>>>>
>>>>>>>> v2:
>>>>>>>> - fix typos
>>>>>>>>
>>>>>>>> fs/f2fs/node.c | 9 ++++++++-
>>>>>>>> 1 file changed, 8 insertions(+), 1 deletion(-)
>>>>>>>>
>>>>>>>> diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c
>>>>>>>> index e632de10aedab..e0bb0f7e0506e 100644
>>>>>>>> --- a/fs/f2fs/node.c
>>>>>>>> +++ b/fs/f2fs/node.c
>>>>>>>> @@ -1520,8 +1520,15 @@ static int __write_node_page(struct page *page, bool atomic, bool *submitted,
>>>>>>>>
>>>>>>>> trace_f2fs_writepage(page, NODE);
>>>>>>>>
>>>>>>>> - if (unlikely(f2fs_cp_error(sbi)))
>>>>>>>> + if (unlikely(f2fs_cp_error(sbi))) {
>>>>>>>> + if (is_sbi_flag_set(sbi, SBI_IS_CLOSE)) {
>>>>>>>> + ClearPageUptodate(page);
>>>>>>>> + dec_page_count(sbi, F2FS_DIRTY_NODES);
>>>>>>>> + unlock_page(page);
>>>>>>>> + return 0;
>>>>>>>> + }
>>>>>>>> goto redirty_out;
>>>>>>>> + }
>>>>>>>>
>>>>>>>> if (unlikely(is_sbi_flag_set(sbi, SBI_POR_DOING)))
>>>>>>>> goto redirty_out;
>>>>>>>>
>>>>>> .
>>>>>>
>>>>>
>>>>>
>>>>> _______________________________________________
>>>>> Linux-f2fs-devel mailing list
>>>>> Linux-f2fs-devel@lists.sourceforge.net
>>>>> https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel
>>>>> .
>>>>>
>>> .
>>>
> .
>

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