Re: [PATCH 3/3] reiser4: in our own sync writes, mark pages dirty before marking them writeback.

[Edward Shishkin <edward.shishkin@gmail.com>]

On 10/09/2015 03:50 PM, Ivan Shapovalov wrote:
> On 2015-10-09 at 15:27 +0200, Edward Shishkin wrote:
>> Hi Ivan,
>>
>> On 10/09/2015 01:16 PM, Ivan Shapovalov wrote:
>>> Ref.: https://www.mail-archive.com/linux-f2fs-devel%40lists.sourcef
>>> orge.net/msg02745.html
>> Do you have a stack trace for reiser4?
>> How to reproduce it?
> I'll rebuild the kernel without the fix and provide you with the oops'
> stacktrace asap.
>
> I guess that it's tied to the config. In my case, it is reproducible on
> each boot, just as the DE starts up and something issues the first
> fsync().


Yes, let's try to find the culprit who doesn't set i_wb...


>
>>> Signed-off-by: Ivan Shapovalov <intelfx100@gmail.com>
>>> ---
>>>
>>> Lustre seemed to encounter the same oops and fixed it in a
>>> different way, removing
>>> set_page_writeback() altogether:
>>> https://lkml.org/lkml/2015/7/30/806
>>>
>>> We cannot just remove the call to set_page_writeback() at least
>>> because later
>>> we wait on PG_Writeback flag of that page (in jwait_io())... What
>>> is meant by
>>> "synchronous write" in that Lustre patch? Is our write
>>> "synchronous" in the
>>> same sense?
>>
>> Nop.
>> This is a generic function, it doesn't differentiate the writes.
> Well, that lustre vvp_page_prep_write() is generic as well, and that
> patch adds a conditional to differentiate sync/async writes. What is
> meant by "sync" in that context? sync == page is locked until I/O ends?
> Or something else?


Why do you need this?
Reiser4 doesn't lock pages for IO ;)
At least, for formatted nodes..

Edward.