linux-kernel - Re: [PATCH 4/4] Btrfs: add basic DIO read/write support V3

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Message-ID: <20100513153145.GE27011@dhcp231-156.rdu.redhat.com>
Date:	Thu, 13 May 2010 11:31:45 -0400
From:	Josef Bacik <josef@...hat.com>
To:	Christoph Hellwig <hch@...radead.org>
Cc:	Josef Bacik <josef@...hat.com>, linux-btrfs@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
	akpm@...ux-foundation.org
Subject: Re: [PATCH 4/4] Btrfs: add basic DIO read/write support V3

On Thu, May 13, 2010 at 11:14:30AM -0400, Christoph Hellwig wrote:
> On Wed, May 12, 2010 at 04:40:53PM -0400, Josef Bacik wrote:
> > V1->V2
> > -Use __blockdev_direct_IO instead of helper
> > -Use KM_IRQ0 for kmap instead of KM_USER0
> 
> I still don't think this is correct.  The completion can come from
> softirq and hardirq context, and possibly even normal process context.
> You either need to check for all these, or you need to use the generic
> complete in user context helper btrfs has available for other types
> of I/O.
> 

AIO's aio_complete does kmap with KM_IRQ0/1 and it gets called in the same
context as the btrfs completion handler, so if it's ok for aio_complete it
should be ok for btrfs right?  Thanks,

Josef
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