linux-kernel - Re: [PATCH] staging: exfat: use bdev_sync function directly where needed

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Date:   Wed, 02 Oct 2019 15:04:15 -0400
From:   "Valdis Klētnieks" <valdis.kletnieks@...edu>
To:     Saiyam Doshi <saiyamdoshi.in@...il.com>
Cc:     gregkh@...uxfoundation.org, devel@...verdev.osuosl.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] staging: exfat: use bdev_sync function directly where needed

On Wed, 02 Oct 2019 20:47:03 +0530, Saiyam Doshi said:
> fs_sync() is wrapper to bdev_sync(). When fs_sync is called with
> non-zero argument, bdev_sync gets called.
>
> Most instances of fs_sync is called with false and very few with
> true. Refactor this and makes direct call to bdev_sync() where
> needed and removes fs_sync definition.

Did you do an actual analysis of where bdev_sync() *should*
be called?

The note in the TODO was intended to point out that many of the calls
are called with 'false' and probably should not be.

 #ifdef CONFIG_EXFAT_DELAYED_SYNC
-	fs_sync(sb, false);
 	fs_set_vol_flags(sb, VOL_CLEAN);
 #endif

Consider - with this patch, we are now setting the volume state to clean - but
we've not actually flushed the filesystem to disk, which means it's almost
guaranteed that the file system is *NOT* in fact clean.

Changing all the 'false' that happen before a VOL_CLEAN to 'true' is
probably more correct - but still totally wrong if DELAYED_SYNC isn't defined
because then we *aren't* syncing to disk at all.

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