linux-kernel - Re: [PATCH 0/2] sys_write() should write all valid data

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Message-ID: <87eiurzfkd.wl%vmayatsk@redhat.com>
Date:	Thu, 14 May 2009 20:48:18 +0200
From:	Vitaly Mayatskikh <v.mayatskih@...il.com>
To:	Josef Bacik <josef@...hat.com>
Cc:	Vitaly Mayatskikh <v.mayatskih@...il.com>, sandeen@...hat.com,
	linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 0/2] sys_write() should write all valid data

At Thu, 14 May 2009 14:02:34 -0400, Josef Bacik wrote:

> Ok all in all I don't think this is a good way to handle this problem.
> Hopefully somebody smarter than I will speak up, but what you are trying to do
> here is have your cake and eat it too.  You want to get the size of what we were
> able to fault in and return that, which should be a size_t,

btw, fault_in_pages_readable() has argument `size' of type int...

> but you also want to
> throw back an error if something happened, which needs a signed value.  I think
> the best way to handle this would be to make check_readable_bytes return size_t,
> and then if you get an EFAULT back, have it return 0.  Then the caller can say
> "hey I couldn't fault anything in, let me make what I want to fault in smaller",
> and then if that fault returns 0 we can exit.

Won't it be suboptimal to trap in the same place twice?

> I hope thats helpful/correct :).

-- 
wbr, Vitaly
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