linux-kernel - Re: CONFIG_VFAT_FS

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Date:	Fri, 3 Jul 2009 11:40:21 +0200 (CEST)
From:	Jan Engelhardt <jengelh@...ozas.de>
To:	tridge@...ba.org
cc:	OGAWA Hirofumi <hirofumi@...l.parknet.co.jp>,
	Theodore Tso <tytso@....edu>,
	Alan Cox <alan@...rguk.ukuu.org.uk>,
	Rusty Russell <rusty@...tcorp.com.au>,
	Pavel Machek <pavel@....cz>, john.lanza@...ux.com,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	linux-fsdevel@...r.kernel.org,
	Dave Kleikamp <shaggy@...ux.vnet.ibm.com>, corbet@....net,
	jcm@...masters.org
Subject: Re: CONFIG_VFAT_FS_DUALNAMES regressions

On Friday 2009-07-03 05:25, tridge@...ba.org wrote:
>
>That is why setting shortname=winnt is desirable when using the "no
>dualnames" patch I posted. That tells Linux to behave more like what
>current windows versions behave, which is to try and put it in the 8.3
>entry if it can, even if it is all lowercase.

Right. That in itself is fine, but I'd still like to have readdir
return lowercase names here then. This is sort of what I seem to
remember from Windows: files only having a total-uppercase 8.3
name were still displayed as lowercase. This is why I am all for
splitting the shortcase option. (Maybe patches speak louder but
ATM I am so into Netfilter ;)

>btw, if you still think your camera really is looking at the long
>filename entries,

I toyed with the hexeditor a bit and modified the FAT entry's
filename directly. (I just hope there is not any checksum?)

 * if a filename is of the form /dscf????.jpg/i, the A210 requires
   that 8.3 names be all uppercase (even in the persence of a
   freeform long name) otherwise the OSD will (explicitly) display
   "READ ERROR".

 * if the 8.3 name is, for example, DsCE1234.jpg, the OSD seems to
   be confused and displays "00000000" as the picture index.

 => So uppercase 8.3 is a hard requirement for _any_ filename.

I also looked again at the finepix.img.bz2 I made available earlier.
It has a long entry "dscf3000.jpg", but "no shortname" (i.e. an
invalid one as generated by the patch), and that is most likely the
reason that the camera ignores this file completely.

>then try creating a file like DsCf2000.jpg with a
>unpatched kernel, mounted with shortname=winnt. That will create two
>directory entries for the file, one being DSCF2000.JPG and the other
>being DsCf2000.jpg.
>
>Then view the list of photos on the LCD back panel of your
>camera. Assuming it has a way to see the filename, does it display the
>mixed case name DsCf2000.jpg, or does it display a non-mixed name like
>dscf2000.jpg or DSCF2000.JPG.

It does not display the filename, just the index number. But the
image is present/selectable, because the 8.3 name is present and is
all-uppercase (see above).

>If it displays a mixed name (ie. DsCf) then your camera can indeed
>read long filename entries. If it displays a all uppercase or all
>lowercase name then I think it is only capable of reading short names
>from FAT filesystems. That is what I think you will find.

Capable or not — it only /needs/ 8.3 for DCIM operation :)
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