Hi Yuezhang > When call exfat_clear_volume_dirty(sb), all dirty buffers had synced by > sync_blockdev(), so I think REQ_FUA/REQ_PREFLUSH is not needed. I think Kohada-san's meaning is like below: - sync_dirty_buffer(sbi->boot_bh); + __sync_dirty_buffer(sbi->boot_bh, REQ_SYNC | REQ_FUA | REQ_PREFLUSH); I guess sync_blockdev() won't guarantee sync to non-volatile storage if disk contains cache. Best Regards Andy Wu > -----Original Message----- > From: Mo, Yuezhang <Yuezhang.Mo@xxxxxxxx> > Sent: Wednesday, March 16, 2022 5:18 PM > To: Namjae Jeon <linkinjeon@xxxxxxxxxx>; > Kohada.Tetsuhiro@xxxxxxxxxxxxxxxxxxxxxxxxxxx > Cc: sj1557.seo@xxxxxxxxxxx; linux-fsdevel@xxxxxxxxxxxxxxx; > linux-kernel@xxxxxxxxxxxxxxx; Wu, Andy <Andy.Wu@xxxxxxxx>; Aoyama, > Wataru (SGC) <Wataru.Aoyama@xxxxxxxx> > Subject: RE: [PATCH v2] exfat: do not clear VolumeDirty in writeback > > Hi Namjae, Kohada.Tetsuhiro, > > > >> - if (sync) > > >> - sync_dirty_buffer(sbi->boot_bh); > > >> + sync_dirty_buffer(sbi->boot_bh); > > >> + > > > > > > Use __sync_dirty_buffer() with REQ_FUA/REQ_PREFLUSH instead to > > > guarantee a strict write order (including devices). > > Yuezhang, It seems to make sense. Can you check this ? > > > > When call exfat_clear_volume_dirty(sb), all dirty buffers had synced by > sync_blockdev(), so I think REQ_FUA/REQ_PREFLUSH is not needed. > > ``` > sync_blockdev(sb->s_bdev); > if (exfat_clear_volume_dirty(sb)) ``` > > exfat_clear_volume_dirty() is only called in sync or umount context. > In sync or umount context, all requests will be issued with REQ_SYNC > regardless of whether REQ_SYNC is set when submitting buffer. > > And since the request of set VolumeDirty is issued with REQ_SYNC. So for > simplicity, call sync_dirty_buffer() unconditionally. > > Best Regards, > Yuezhang Mo >
