| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Date: Sun, 09 Nov 2014 18:57:27 +0200
From: Boaz Harrosh <boaz@...xistor.com>
To: Karel Zak <kzak@...hat.com>, Jens Axboe <axboe@...com>,
Dave Chinner <david@...morbit.com>
CC: Matthew Wilcox <willy@...ux.intel.com>,
Dmitry Monakhov <dmonakhov@...nvz.org>,
linux-kernel <linux-kernel@...r.kernel.org>,
linux-fsdevel <linux-fsdevel@...r.kernel.org>
Subject: Re: [PATCH 5/5] brd: Add getgeo to block ops for fdisk
On 11/07/2014 11:23 AM, Karel Zak wrote:
> On Wed, Nov 05, 2014 at 04:10:50PM +0200, Boaz Harrosh wrote:
>> From: Boaz Harrosh <boaz@...xistor.com>
>>
>> Now when fdisk is run on brd it will ask some cryptic
>> questions about CHS. This is because the getgeo block operation
>> is not implemented.
>
> Again, what fdisk (util-linux) version?
>
Hi Karel, Dave and Jens
With Fedora 20 > "fdisk from util-linux 2.24.2"
>> I have done a quick audit of the fdisk code. The CHS calculation
>> is very convoluted but at the end it comes out with a number.
>> Which is taken into consideration in first-sector to allow. With
>> all 1(s) this numbers is very small and other numbers come into
>> account. Also note that if the device is big like 1G (not sure what
>> is the threshold) fdisk will offer 1M (2048) as possible first-
>> sector, and it does not matter what numbers we give here.
>
> oh.. sounds like archeology, CHS calculation does not mater in the
> current code, it follows I/O limits (including crazy alignment
> offset).
>
with a small 4M disk
I see brd_getgeo() getting called on fdisk load and when pressing
g or o. But it no longer has any effect at all if I have it defined
returning CHS(4,64,32) or returning CHS(1,1,1) or not defined at all
I get the same exact below experience:
(Dropping the none-relevant prompts)
======== *WITHOUT* 4k physical_block_size PATCH ===============================================================
Command (m for help): g
Command (m for help): n
First sector (34-8158, default 34):
Last sector, +sectors or +size{K,M,G,T,P} (34-8158, default 8158): 1717
Command (m for help): n
First sector (1718-8158, default 1718):
# NOTE first sector is last "prev-end" + 1
Last sector, +sectors or +size{K,M,G,T,P} (1718-8158, default 8158):
Command (m for help): p
Disk /dev/ram0: 4 MiB, 4194304 bytes, 8192 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: gpt
Disk identifier: 5C14F69F-EA44-4FE3-984A-9948D6AB7628
Device Start End Size Type
/dev/ram0p1 34 1717 842K Linux filesystem
/dev/ram0p2 1718 8158 3.1M Linux filesystem
---
Command (m for help): o
Command (m for help): n
First sector (1-8191, default 1):
Last sector, +sectors or +size{K,M,G,T,P} (1-8191, default 8191): 1717
Command (m for help): n
First sector (1718-8191, default 1718):
# NOTE same here
Last sector, +sectors or +size{K,M,G,T,P} (1718-8191, default 8191):
Command (m for help): p
Disk /dev/ram0: 4 MiB, 4194304 bytes, 8192 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: dos
Disk identifier: 0xe5c9e1b1
Device Boot Start End Blocks Id System
/dev/ram0p1 1 1717 858+ 83 Linux
/dev/ram0p2 1718 8191 3237 83 Linux
======== 4k physical_block_size PATCH ===============================================================
Command (m for help): g
Command (m for help): n
First sector (34-8158, default 40):
Last sector, +sectors or +size{K,M,G,T,P} (40-8158, default 8158): 1717
Command (m for help): n
First sector (34-8158, default 1720):
# NOTE 34-8158 again, only with gpt
Last sector, +sectors or +size{K,M,G,T,P} (1720-8158, default 8158):
Command (m for help): p
Disk /dev/ram0: 4 MiB, 4194304 bytes, 8192 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: gpt
Disk identifier: 892E3C8A-3942-4C06-9B5B-6BA6B5A84AB9
Device Start End Size Type
/dev/ram0p1 40 1717 839K Linux filesystem
/dev/ram0p2 1720 8158 3.1M Linux filesystem
---
Command (m for help): o
Command (m for help): n
First sector (8-8191, default 8):
Last sector, +sectors or +size{K,M,G,T,P} (8-8191, default 8191): 1717
Command (m for help): n
First sector (1718-8191, default 1720):
# NOTE with dos its good
Last sector, +sectors or +size{K,M,G,T,P} (1720-8191, default 8191):
Command (m for help): p
Disk /dev/ram0: 4 MiB, 4194304 bytes, 8192 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: dos
Disk identifier: 0xaa069afe
Device Boot Start End Blocks Id System
/dev/ram0p1 8 1717 855 83 Linux
/dev/ram0p2 1720 8191 3236 83 Linux
=======
So I'm dropping the getgeo() patch all together. It is now fixed with new
util-linux 2.24.2 and is not needed at all. (Before fdisk gave me a prompt
on load without it)
Jens please drop this patch titled:
[PATCH 5/5] brd: Add getgeo to block ops for fdisk
Dave, Karel, what would you say fdisk should do? do you think it behaves correctly
to only align with the 4k-physical_block_size or must it always align ?
So it looks like we still need the 4k-physical_block_size PATCH for current
fdisk, I don't mind if it is decided to be fixed in user-mode then we can
drop this patch as well.
[ For Karel 2 things:
- It looks like getgeo has no effect (Is it used at all?), you might want to
remove the call. (libgparted does not use it)
- Checkout the small bug above with gpt and first-sector of second partition
]
Many Thanks
Boaz
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
Powered by blists - more mailing lists