linux-kernel - Re: vfat: Broken case-insensitive support for UTF-8

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Message-ID: <20200121224633.lxitgyx6bw47crri@pali>
Date:   Tue, 21 Jan 2020 23:46:33 +0100
From:   Pali Rohár <pali.rohar@...il.com>
To:     Al Viro <viro@...iv.linux.org.uk>
Cc:     OGAWA Hirofumi <hirofumi@...l.parknet.co.jp>,
        linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
        "Theodore Y. Ts'o" <tytso@....edu>,
        Namjae Jeon <linkinjeon@...il.com>,
        Gabriel Krisman Bertazi <krisman@...labora.com>
Subject: Re: vfat: Broken case-insensitive support for UTF-8

On Tuesday 21 January 2020 22:14:47 Al Viro wrote:
> On Tue, Jan 21, 2020 at 09:36:25PM +0000, Al Viro wrote:
> > On Tue, Jan 21, 2020 at 09:34:05PM +0100, Pali Rohár wrote:
> > 
> > > This is a great idea to get FAT equivalence classes. Thank you!
> > > 
> > > Now I quickly tried it... and it failed. FAT has restriction for number
> > > of files in a directory, so I would have to do it in more clever way,
> > > e.g prepare N directories and then try to create/open file for each
> > > single-point string in every directory until it success or fail in every
> > > one.
> > 
> > IIRC, the limitation in root directory was much harder than in
> > subdirectories...  Not sure, though - it had been a long time since
> > I had to touch *FAT for any reasons...

IIRC limit for root directory entry was only in FAT12 and FAT16. But I
already used subdirectories. Also VFAT name occupies at least two
entries (shortname + VFAT).

> Interesting...  FWIW, Linux vfat happily creates 65536 files in root
> directory.  What are the native limits?

Interesting... When I tried to create a new file by Linux vfat in that
directory where Windows created 32794 files, Linux vfat returned error
"No space left on device" even FS has only 39% used space. Into upper
directory linux vfat can put new file without any problem.

-- 
Pali Rohár
pali.rohar@...il.com

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