UDF filesystem has some bugs on truncating

UDF filesystem has some bugs on truncating

[colin]

Hi all,
I found that UDF has bugs on truncating.
When you do this:
    dd if=/dev/zero of=aaa bs=1024k count=2 seek=3000
, Linux will hang and die.
The platform is Linux 2.6.16 on MIPS malta board.

Regards,
Colin

Re: UDF filesystem has some bugs on truncating

[Alan Cox]

Ar Gwe, 2006-06-16 am 13:47 +0800, ysgrifennodd colin:
> Hi all,
> I found that UDF has bugs on truncating.
> When you do this:
>     dd if=/dev/zero of=aaa bs=1024k count=2 seek=3000
> , Linux will hang and die.

I'm unable to duplicate this on x86-64, do you have more information, eg
backtraces ?

Re: UDF filesystem has some bugs on truncating

[Alan Cox]

Ar Gwe, 2006-06-16 am 13:47 +0800, ysgrifennodd colin:
> Hi all,
> I found that UDF has bugs on truncating.
> When you do this:
>     dd if=/dev/zero of=aaa bs=1024k count=2 seek=3000
> , Linux will hang and die.
> The platform is Linux 2.6.16 on MIPS malta board.

Ok I eventually sort of reproduced this on x86-64. It took a while
because in my environment I see a crash 2 or 3 hours after the test is
run, and that crash is on hardware that doesn't otherwise crash and
seems to be repeatable.

Alan

Re: UDF filesystem has some bugs on truncating

[colin]

Hi Alan,
Do you use the same command with me?
The parameter "seek" of "dd if=/dev/zero of=aaa bs=1024k count=2 seek=3000"
will inform "dd" to use truncate system call to expand file in no time.
In normal situations, the file will grow up to 3G in about 2 seconds.
This dd command on ext3 partition can run very well on my platform, but it
will fail on UDF partition.

Regards,
Colin


----- Original Message ----- 
From: "Alan Cox" <alan@lxorguk.ukuu.org.uk>
To: "colin" <colin@realtek.com.tw>
Cc: <linux-kernel@vger.kernel.org>
Sent: Monday, June 19, 2006 5:32 PM
Subject: Re: UDF filesystem has some bugs on truncating


> Ar Gwe, 2006-06-16 am 13:47 +0800, ysgrifennodd colin:
> > Hi all,
> > I found that UDF has bugs on truncating.
> > When you do this:
> >     dd if=/dev/zero of=aaa bs=1024k count=2 seek=3000
> > , Linux will hang and die.
> > The platform is Linux 2.6.16 on MIPS malta board.
>
> Ok I eventually sort of reproduced this on x86-64. It took a while
> because in my environment I see a crash 2 or 3 hours after the test is
> run, and that crash is on hardware that doesn't otherwise crash and
> seems to be repeatable.
>
> Alan
>