linux-kernel - RE: [PATCH 0/2] make all stored entries accessible.

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Date:	Thu, 31 Oct 2013 14:35:33 +0000
From:	Seiji Aguchi <seiji.aguchi@....com>
To:	Madper Xie <bbboson@...il.com>, "Luck, Tony" <tony.luck@...el.com>
CC:	Madper Xie <cxie@...hat.com>,
	"keescook@...omium.org" <keescook@...omium.org>,
	"ccross@...roid.com" <ccross@...roid.com>,
	"anton@...msg.org" <anton@...msg.org>,
	"linux-efi@...r.kernel.org" <linux-efi@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH 0/2] make all stored entries accessible.



> 1. combine timestamp, count and part into "id".
>    for now, in efi-pstore.c, *id = part. and we could simply change it
>    to unique one. F.E. *id = (timestamp * 100 + part) * 100 + count.

My opinion close to 1.
But, the "*id" should not be the complex one like (timestamp * 100 + part) * 100 + count.
Rather, it should be a simple sequential number beginning with 1.

 - Remove "id" member from pstore_read_info struct.
 -  Introduce a global sequential counter like "static u64 efi_pstore_read_count" (or add the member to pstore_info structure?)
 - Initialize to "1" in efi_pstore_open().
 - Increment it in efi_pstore_read().

If we can do it, we don't need to touch a code of pstore filesystem and can avoid regressions of
other backend drivers.

Seiji

> -----Original Message-----
> From: linux-efi-owner@...r.kernel.org [mailto:linux-efi-owner@...r.kernel.org] On Behalf Of Madper Xie
> Sent: Wednesday, October 30, 2013 11:01 PM
> To: Luck, Tony
> Cc: Seiji Aguchi; Madper Xie; keescook@...omium.org; ccross@...roid.com; anton@...msg.org; linux-efi@...r.kernel.org; linux-
> kernel@...r.kernel.org; bbboson@...il.com
> Subject: Re: [PATCH 0/2] make all stored entries accessible.
> 
> 
> tony.luck@...el.com writes:
> 
> >> So, do you mean efivars should fix to use the "id" in a proper way?
> >
> > It would avoid the need for all these tests, and additions to the filename to guarantee
> > uniqueness.
> >
> > Not sure what options efivars has to create a unique, persistent "id" for each
> > record.  It's a fundamental part of how ERST works (though the unique ID is just
> > based around a timestamp).
> >
> Okay, maybe there are three options here:
> 1. combine timestamp, count and part into "id".
>    for now, in efi-pstore.c, *id = part. and we could simply change it
>    to unique one. F.E. *id = (timestamp * 100 + part) * 100 + count.
> 2. change the id's type. let id become a string.
>    so every backend could write anything to id. then it will become a
>    part of filename in pstore filesystem. (but we need fix all backends
>    since we modified api.)
> 3. apply the patches I have sent... even if the filename will be ugly
>    and gory...
> Which one do you prefer?
> >> I acked Madper's patch 2/2 earlier today, but when I look at your test result, I'm not sure if
> >> it is reasonable for users to make multiple numbers visible to the file name.
> >>
> >>> -r--r--r-- 1 root root 17499 Oct 30 13:41 dmesg-erst-5940651313304961029--2129078373-1383165669
> >
> > after I added the "count = 0" initialization the filename gets a tiny bit less
> > scary:
> >
> > -r--r--r-- 1 root root 17499 Oct 30 13:41 dmesg-erst-5940651313304961029-0-1383165669
> >
> > -Tony
> 
> 
> --
> Best,
> Madper Xie.
> --
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