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From: Tejun Heo <htejun@gmail.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Dan Williams <dan.j.williams@intel.com>,
	gregkh@suse.de, linux-kernel@vger.kernel.org, neilb@suse.de
Subject: Re: [RFC PATCH] sysfs: refill attribute buffer when reading from offset 0
Date: Mon, 07 Apr 2008 21:43:06 +0900	[thread overview]
Message-ID: <47FA16DA.80700@gmail.com> (raw)
In-Reply-To: <20080405232959.c6504be8.akpm@linux-foundation.org>

Hello,

Andrew Morton wrote:
>>  The application for this change is to allow a userspace
>> RAID metadata handler to check the state of an array without causing any
>> memory allocations.  Thus not causing writeback to a raid array that might
>> be blocked waiting for userspace to take action.
> 
> Although that sounds like a rather, umm, optimistic application.  I guess
> if everything's mlocked you might get lucky.
> 
>> Cc: NeilBrown <neilb@suse.de>
>> Cc: Tejun Heo <htejun@gmail.com>
>> Signed-off-by: Dan Williams <dan.j.williams@intel.com>

Acked-by: Tejun Heo <htejun@gmail.com>

> Has this been tested with pread()?  That should work - doing an lseek+read
> is plain dopey.
> 
> Can we now remove need_read_fill?  Not if we want to support
> open+lseek+read, I guess - this initial read might not be at offset
> zero.

Heh.. needs_read_fill is set after read and poll regardless of file pos 
and I bet there are applications depending on it.  :-(

-- 
tejun

  reply	other threads:[~2008-04-07 12:43 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-04-05 18:41 [RFC PATCH] sysfs: refill attribute buffer when reading from offset 0 Dan Williams
2008-04-06  6:29 ` Andrew Morton
2008-04-07 12:43   ` Tejun Heo [this message]
2008-04-07 22:35   ` Dan Williams

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