* ext2 large block size support - the shocking truth...
@ 2012-03-21 20:38 Risanecek
2012-03-21 21:21 ` Ted Ts'o
0 siblings, 1 reply; 3+ messages in thread
From: Risanecek @ 2012-03-21 20:38 UTC (permalink / raw)
To: linux-kernel
...at least for me.
Hi,
I'm currently having a disassembled TV in my living room, pictures are
similar to http://www.avforums.com/forums/11185338-post214.html
The TV may or may not run Linux, it definitely has a hard disk that
has three ext2 partitions on it, oh yes and it formats every new HDD
you stick into it by giving it three ext2 partitions. I thought I'd
update the hdd, copy the old content to the new - bigger - one and
finito. Quick, no fuzz. If these Windows guys can do it...
Attached the new and old hard disk to my small linux home server,
running kernel 3.2.9 and tried to mount the partitions.
*boom*
# mount -text2 /dev/sdd2 partiton2
mount: wrong fs type, bad option, bad superblock on /dev/sdd2,
missing codepage or helper program, or other error
In some cases useful info is found in syslog - try
dmesg | tail or so
dmesg
EXT2-fs (sdd2): error: bad blocksize 32768
Seems many DVRs use that kind of "enhanced ext2"...
http://ubuntuforums.org/showthread.php?t=1942682
(german) http://www.knoppixforum.de/knoppix-forum-deutsch/retter-in-der-not/thread4912/gel%C3%B6st-externe-hd-wisi-sathd-receiver-or193hd-bearbeiten.html
...
You know, normally I'd think "Ah what the heck, the TV guys did
something incompatible to ext2 - to hell with them.", but there is
this Windows issue:
http://www.ext2fsd.com/ can cope with it, as can
http://www.diskinternals.com/linux-reader/
Ouch! "To add insult to injury" as https://lkml.org/lkml/2011/4/1/159 says
So do I understand correctly, that to be able to read an ext2
filesystem, having a home server running Linux is the wrong choice
here? That I should install Windows on it with one of the
aforementioned programs to be able to read / copy my TVs ext2 hdds?
Shall I shoot myself right now or will a facepalm do? Or - that's why
I'm here - is there a chance my linux box actually COULD read these
data?
Please advise.
cordially,
Richard
^ permalink raw reply [flat|nested] 3+ messages in thread* Re: ext2 large block size support - the shocking truth...
2012-03-21 20:38 ext2 large block size support - the shocking truth Risanecek
@ 2012-03-21 21:21 ` Ted Ts'o
2012-03-22 17:01 ` Christoph Hellwig
0 siblings, 1 reply; 3+ messages in thread
From: Ted Ts'o @ 2012-03-21 21:21 UTC (permalink / raw)
To: Risanecek; +Cc: linux-kernel
On Wed, Mar 21, 2012 at 09:38:33PM +0100, Risanecek wrote:
>
> EXT2-fs (sdd2): error: bad blocksize 32768
>
> Seems many DVRs use that kind of "enhanced ext2"...
It's not an enhanced ext2 as much as it is enhancements primarily in
the mm layer to allow file systems to use a "larger page" which is
larger than the native page size of the CPU's MMU. This is the first
that I've heard of a DVR, or any product in general, actually trying
to use Christoph Lameter's patches in a shipping Linux system.
If you just need to read and write files from this file system from a
userspace CLI shell utility, you could just use the programs from the
e2tools package; they should work just fine. It works much like the
mtools package do to be able to copy, rename, list directories, of an
MSDOS file system, but for ext2/3/4 file systems.
Alternatively, you could try to forward port Christoph's patches to a
modern kernel, or commission someone to port it to a modern for you...
Hope this helps,
- Ted
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: ext2 large block size support - the shocking truth...
2012-03-21 21:21 ` Ted Ts'o
@ 2012-03-22 17:01 ` Christoph Hellwig
0 siblings, 0 replies; 3+ messages in thread
From: Christoph Hellwig @ 2012-03-22 17:01 UTC (permalink / raw)
To: Ted Ts'o, Risanecek, linux-kernel
On Wed, Mar 21, 2012 at 05:21:52PM -0400, Ted Ts'o wrote:
> It's not an enhanced ext2 as much as it is enhancements primarily in
> the mm layer to allow file systems to use a "larger page" which is
> larger than the native page size of the CPU's MMU. This is the first
> that I've heard of a DVR, or any product in general, actually trying
> to use Christoph Lameter's patches in a shipping Linux system.
>
> If you just need to read and write files from this file system from a
> userspace CLI shell utility, you could just use the programs from the
> e2tools package; they should work just fine. It works much like the
> mtools package do to be able to copy, rename, list directories, of an
> MSDOS file system, but for ext2/3/4 file systems.
>
> Alternatively, you could try to forward port Christoph's patches to a
> modern kernel, or commission someone to port it to a modern for you...
Or the device might have a CPU with larger pages. I've seen various
appliances with ppc CPUs that use 64k page and for special applications
even 256k pages. I've also seen XFS and extN filesystem taking
"advantage" of that (not sure if really helped them with their
workloads, or if they did it just because they could)
^ permalink raw reply [flat|nested] 3+ messages in thread
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2012-03-21 20:38 ext2 large block size support - the shocking truth Risanecek
2012-03-21 21:21 ` Ted Ts'o
2012-03-22 17:01 ` Christoph Hellwig
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