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Date: Sat, 10 Feb 2007 10:05:24 -0800
From: "Ken Chen" <kenchen@google.com>
To: "Ananiev, Leonid I" <leonid.i.ananiev@intel.com>
Subject: Re: [PATCH] aio: fix kernel bug when page is temporally busy
Cc: suparna@in.ibm.com, "Andrew Morton" <akpm@linux-foundation.org>,
       linux-kernel@vger.kernel.org, linux-aio <linux-aio@kvack.org>,
       "Zach Brown" <zach.brown@oracle.com>,
       "Chris Mason" <chris.mason@oracle.com>,
       "Badari Pulavarty" <pbadari@us.ibm.com>
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On 2/9/07, Ananiev, Leonid I <leonid.i.ananiev@intel.com> wrote:
> I have used EIOCBRETRY in the patch to minimize source code modification
> only.
> [...]
> A lot of errno's have different meaning in different functions or
> contexts. EAGAIN could be used instated of EIOCBRETRY for irredundant
> set.

I also think the original patch is wrong.  It might shut up kernel
panic by eliminate double calls to aio_complete(), but it will
silently introduce data corruption.

If invalidate_inode_pages2_range() says it can not invalidate pages,
while dio to the same file offset range is in flight, something is
really wrong there.  In generic_file_direct_IO, the function
explicitly flushes all dirty pages and wait on them before submits
DIO.

So any error value returned from invalidate_inode_pages2_range() has
to be taken seriously in the direct IO submit path instead of dropping
it to the floor.

- Ken