linux-kernel - Re: Review status (Re: [PATCH] LogFS take three)

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Message-ID: <20070520173049.GA20907@2ka.mipt.ru>
Date:	Sun, 20 May 2007 21:30:52 +0400
From:	Evgeniy Polyakov <johnpol@....mipt.ru>
To:	Jörn Engel <joern@...ybastard.org>
Cc:	linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-mtd@...ts.infradead.org, akpm@...l.org,
	Albert Cahalan <acahalan@...il.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Jan Engelhardt <jengelh@...ux01.gwdg.de>,
	Pekka Enberg <penberg@...helsinki.fi>,
	Greg KH <greg@...ah.com>, Ingo Oeser <ioe-lkml@...eria.de>
Subject: Re: Review status (Re: [PATCH] LogFS take three)

On Thu, May 17, 2007 at 07:10:19PM +0200, Jörn Engel (joern@...ybastard.org) wrote:
> On Thu, 17 May 2007 20:03:11 +0400, Evgeniy Polyakov wrote:
> > 
> > Is logfs 32bit fs or 674bit, since although you use 64bit values for
> > offsets, area management and strange converstions like described below 
> > from offset into segment number are performed in 32bit?
> > Is it enough for SSD for example to be 32bit only? Or if it is 64bit,
> > could you please explain logic behind area management?
> 
> Ignoring bugs and signed return values for error handling, it is either
> 64bit or 32+32bit.
> 
> Inode numbers and file positions are 64bit.  Offsets are 64bit as well.
> In a couple of places, offsets are also 32+32bit.  Basically the high
> bits contain the segment number, the lower bits the offset within a
> segment.

In that case segment size must be more than 32 bits, or below
transformation will not be correct? segsize is long, but should be u64 I
think.

static void fixup_from_wbuf(struct super_block *sb, struct logfs_area
	*area, void *read, u64 ofs, size_t readlen)

u32 read_start = ofs & (super->s_segsize - 1);
u32 read_end = read_start + readlen;

And this can overflow, since readlen is size_t.
It is wbuf fixup, but I saw that somewhere else.
Although, according to your description, it should be 32bit, sum can be
more than 32 bit.

> If anyone can find similar bugs, the bounty is a beer or non-alcoholic
> beverage of choice. :)

Stop kiling your kidneys, your health and promote such antisocial style
of life, start drinking vodka instead.

> Jörn

-- 
	Evgeniy Polyakov
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