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Re: [PATCH] Remove DIO_OWN_LOCKING

To: Russell Cattelan <cattelan@xxxxxxxxxxx>
Subject: Re: [PATCH] Remove DIO_OWN_LOCKING
From: David Chinner <dgc@xxxxxxx>
Date: Fri, 13 Oct 2006 12:48:30 +1000
Cc: linux-fsdevel@xxxxxxxxxxxxxxx, xfs@xxxxxxxxxxx
In-reply-to: <1160700998.5723.65.camel@xenon.msp.redhat.com>
References: <1160700998.5723.65.camel@xenon.msp.redhat.com>
Sender: xfs-bounce@xxxxxxxxxxx
User-agent: Mutt/1.4.2.1i
On Thu, Oct 12, 2006 at 07:56:38PM -0500, Russell Cattelan wrote:
> While trying to fix up GFS2 directio and reading through the code
> involving the various lock flags I discovered the DIO_OWN_LOCKING 
> flag is no longer used.
>  
> XFS recently changed it xfs_vm_direct_IO function to call
> blockdev_direct_IO_no_locking for reads and
> blockdev_direct_IO_own_locking
> for writes. But DIO_OWN_LOCKING is only used in the direct IO read case
> so effectively the flag is never checked an therefore can probably be
> removed.

NACK.

This breaks XFS direct writes - the DIO_OWN_LOCKING flag has meaning
for direct writes even though a simple grep doesn't give you any
hits. get_more_blocks() sets the create flag unconditionally on
writes when DIO_OWN_LOCKING is set, and this is needed for XFS to be
able to allocate underlying blocks if the direct write is over a
hole or past EOF.

Cheers,

Dave.
-- 
Dave Chinner
Principal Engineer
SGI Australian Software Group


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