Re: [PATCH 1/1] fs/mpage.c: forgotten WRITE_SYNC in case of data integrity write

Roman Peniaev
2014-03-14T14:30:03Z

On Fri, Mar 14, 2014 at 11:20 PM, Tejun Heo <tj@kernel.org> wrote:
> On Fri, Mar 14, 2014 at 11:17:56PM +0900, Roman Peniaev wrote:
>> No, no. Not device does not support flush, filesystem does not care about flush.
>> (take any old school, e.g. ext2)
>>
>> We did some write, and then we did fsync.
>> But filesystem does not support REQ_FLUSH/FUA so block device will never
>> get the checkpoint where it should really flush everything.
>>
>> So, fsync will not guarantee any integrity in that case.
>
> Oh, no idea. Fix the filesystem to support REQ_FLUSH? :)

Yep, best variant. But I was thinking that there should be some guarantees
from fsync (and friends) calls, which will issue flush after completion of every
writeback request. But no way

>
> --
> tejun