linux-kernel - Re: MS_SILENT vs. vfat and hfs

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Date:	Wed, 02 Mar 2011 23:14:28 +0900
From:	OGAWA Hirofumi <hirofumi@...l.parknet.co.jp>
To:	Karel Zak <kzak@...hat.com>
Cc:	linux-kernel@...r.kernel.org, t.artem@...lcity.com,
	Roman Zippel <zippel@...ux-m68k.org>
Subject: Re: MS_SILENT vs. vfat and hfs

Karel Zak <kzak@...hat.com> writes:

>  The mount(8) command uses "quiet" mount option as a synonym to the
>  MS_SILENT mount flag (since util-linux 2.7, Aug 1997).
>
>  It means than on systems where is properly defined the MS_SILENT
>  mount flags in headers is the "quiet" mount option always translated
>  to the MS_SILENT mount flags and "quiet" string is never send to FS
>  drivers.
>
>    $ strace -e mount mount -o quiet /dev/sdb1 /mnt/test
>    mount("/dev/sdb1", "/mnt/test", "vfat", MS_MGC_VAL|MS_SILENT, NULL) = 0
>                                                       ^^^^^^^^^
>
>  Unfortunately, 
>  
>    $ grep -r \"quiet\" *
>
>    fat/inode.c:    {Opt_quiet, "quiet"},
>    hfs/super.c:    { opt_quiet, "quiet" },
>
>  vfat and hfs drivers use "quiet" as a mount option. That's bug.
>
>  There should not be a collision between mount(8) mount options and
>  filesystem specific mount options.
>
>  My suggestion is to fix the fat and hfs code to use something other
>  than "quiet" (shutup, noisless, ...). I think you don't have to care
>  about backward compatibility, because it's probably broken for years.

No. Actually the _new_ option is MS_SILENT. In history, there was no
MS_SILENT (it was called MS_VERBOSE) in kernel, then _added_ newly, and
never be enabled MS_SILENT in mount command until that.

So, my suggestion is use "silent" (or something) as MS_SILENT for
backward compatibility. Because the "quiet" is already hardcoded by some
userland apps for vfat.

Thanks.
-- 
OGAWA Hirofumi <hirofumi@...l.parknet.co.jp>
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