linux-kernel - Re: How to register block device as read-only

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Message-Id: <1185622574.3655.11.camel@gimli.at.home>
Date:	Sat, 28 Jul 2007 13:36:14 +0200
From:	Bernd Petrovitsch <bernd@...mix.at>
To:	beck0778@....edu
Cc:	linux-kernel@...r.kernel.org
Subject: Re: How to register block device as read-only

On Fri, 2007-07-27 at 13:07 -0500, beck0778@....edu wrote:
> Hello,
> 
> In a block device driver, how do you tell the kernel that your block device 
> is read-only? Is it in the registration of the gendisk, or is there an 
> ioctl I should be catching to inform the kernel (and user) that this disk 
> is read-only?

Unless I misunderstand the question, the "write" and "writev" function
of the "struct file_operations" should return an appropriate error value
(which is here -EACCES).
You may think of returning an error in the "open" if someone wants to
open it to write to it (so that the must open it read-only).
But I don't know if that is common practice or not (or even disliked) as
it may interfere with not properly implemented tools which open devices
read-write even if they never write to it.

	Bernd
-- 
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