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From: Nick Piggin <nickpiggin@yahoo.com.au>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Badari Pulavarty <pbadari@us.ibm.com>,
	Bill Irwin <bill.irwin@oracle.com>,
	nacc@us.ibm.com, lkml <linux-kernel@vger.kernel.org>,
	linux-mm <linux-mm@kvack.org>
Subject: Re: [PATCH] hugetlbfs read() support
Date: Fri, 20 Jul 2007 16:13:04 +1000	[thread overview]
Message-ID: <46A05270.5040205@yahoo.com.au> (raw)
In-Reply-To: <20070719095850.6e09b0e8.akpm@linux-foundation.org>

(sorry if this is a resend... something bad seems to have happened to me)

Andrew Morton wrote:
> On Thu, 19 Jul 2007 08:51:49 -0700 Badari Pulavarty <pbadari@us.ibm.com> wrote:

>>>This code doesn't have all the ghastly tricks which we deploy to handle
>>>concurrent truncate.
>>
>>Do I need to ? Baaahh!!  I don't want to deal with them. 
> 
> 
> Nick, can you think of any serious consequences of a read/truncate race in
> there?  I can't..

As it doesn't allow writes, then I _think_ it should be OK. If you
ever did want to add write(2) support, then you would have transient
zeroes problems.

But I'm not completely sure.. we've had a lot of (and still have
some known and probably unknown) bugs just in that single
generic_mapping_read function, most of which are due to our rabid
aversion to doing any locking whatsoever there.

So why not just hold i_mutex around the whole thing to be safe?

-- 
SUSE Labs, Novell Inc.

WARNING: multiple messages have this Message-ID (diff)
From: Nick Piggin <nickpiggin@yahoo.com.au>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Badari Pulavarty <pbadari@us.ibm.com>,
	Bill Irwin <bill.irwin@oracle.com>,
	nacc@us.ibm.com, lkml <linux-kernel@vger.kernel.org>,
	linux-mm <linux-mm@kvack.org>
Subject: Re: [PATCH] hugetlbfs read() support
Date: Fri, 20 Jul 2007 16:13:04 +1000	[thread overview]
Message-ID: <46A05270.5040205@yahoo.com.au> (raw)
In-Reply-To: <20070719095850.6e09b0e8.akpm@linux-foundation.org>

(sorry if this is a resend... something bad seems to have happened to me)

Andrew Morton wrote:
> On Thu, 19 Jul 2007 08:51:49 -0700 Badari Pulavarty <pbadari@us.ibm.com> wrote:

>>>This code doesn't have all the ghastly tricks which we deploy to handle
>>>concurrent truncate.
>>
>>Do I need to ? Baaahh!!  I don't want to deal with them. 
> 
> 
> Nick, can you think of any serious consequences of a read/truncate race in
> there?  I can't..

As it doesn't allow writes, then I _think_ it should be OK. If you
ever did want to add write(2) support, then you would have transient
zeroes problems.

But I'm not completely sure.. we've had a lot of (and still have
some known and probably unknown) bugs just in that single
generic_mapping_read function, most of which are due to our rabid
aversion to doing any locking whatsoever there.

So why not just hold i_mutex around the whole thing to be safe?

-- 
SUSE Labs, Novell Inc.

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  parent reply	other threads:[~2007-07-21  1:36 UTC|newest]

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-07-14  1:23 [PATCH] hugetlbfs read() support Badari Pulavarty
2007-07-14  1:23 ` Badari Pulavarty
2007-07-19  5:19 ` Andrew Morton
2007-07-19  5:19   ` Andrew Morton
2007-07-19 15:51   ` Badari Pulavarty
2007-07-19 15:51     ` Badari Pulavarty
2007-07-19 16:58     ` Andrew Morton
2007-07-19 16:58       ` Andrew Morton
2007-07-19 17:07       ` Nishanth Aravamudan
2007-07-19 17:07         ` Nishanth Aravamudan
2007-07-19 17:52         ` Bill Irwin
2007-07-19 17:52           ` Bill Irwin
2007-07-31  5:57           ` dean gaudet
2007-07-31  5:57             ` dean gaudet
2007-07-20  4:47         ` Nick Piggin
2007-07-20  4:47           ` Nick Piggin
2007-07-23 14:02           ` Nishanth Aravamudan
2007-07-23 14:02             ` Nishanth Aravamudan
2007-07-20  4:29       ` Nick Piggin
2007-07-20  4:29         ` Nick Piggin
2007-07-20 21:15         ` Badari Pulavarty
2007-07-20 21:15           ` Badari Pulavarty
2007-07-20  4:39       ` Nick Piggin
2007-07-20  4:39         ` Nick Piggin
2007-07-20  6:13       ` Nick Piggin [this message]
2007-07-20  6:13         ` Nick Piggin

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