linux-kernel - RE: [PATCH] exfat: do not clear VolumeDirty in writeback

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Date:   Mon, 7 Mar 2022 05:34:17 +0000
From:   "Kohada.Tetsuhiro@...MitsubishiElectric.co.jp" 
        <Kohada.Tetsuhiro@...MitsubishiElectric.co.jp>
To:     unlisted-recipients:; (no To-header on input)
CC:     "linux-fsdevel@...r.kernel.org" <linux-fsdevel@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "sj1557.seo@...sung.com" <sj1557.seo@...sung.com>
Subject: RE: [PATCH] exfat: do not clear VolumeDirty in writeback

Hi, Yuezhang,Mo

> > >(PS: The original logic is to clear VolumeDirty after BitMap, FAT and directory
> > entries are updated.)
> >
> > However, the writing order was not guaranteed.
> > More synchronous writes are needed to guarantee the write order.
> 
> If "dirsync" or "sync" is enabled, BitMap, FAT and directory entries are guaranteed to be written in order.
> This is the reason to keep clearing VolumeDirty.

SB_DIRSYNC requests synchronization of the inode of the current file/dir.
The exfat implementation updates and syncs the dir-entries of the current file/dir.
If only SB_DIRSYNC is set and SB_SYNC is not set, it cannot be guaranteed that FAT/mirrorFAT is synchronized.

BR
T .Kohada