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Subject: Re: [PATCH] NFS: account direct-io into task io accounting
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From: Chuck Lever <chuck.lever@oracle.com>
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Date: Mon, 21 Feb 2011 12:17:15 -0800
Cc: linux-nfs@vger.kernel.org, Trond Myklebust <Trond.Myklebust@netapp.com>,
        linux-kernel@vger.kernel.org
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To: Konstantin Khlebnikov <khlebnikov@openvz.org>
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On Feb 21, 2011, at 11:15 AM, Konstantin Khlebnikov wrote:

> Account complete NFS direct-io reads and writes into Task I/O Accounting.
> 
> NFS have unusual direct-io implementation,
> thus accounting in generic code does not work.
> 
> Signed-off-by: Konstantin Khlebnikov <khlebnikov@openvz.org>
> ---
> fs/nfs/direct.c |    9 +++++++--
> 1 files changed, 7 insertions(+), 2 deletions(-)
> 
> diff --git a/fs/nfs/direct.c b/fs/nfs/direct.c
> index 9943a75..bab4185 100644
> --- a/fs/nfs/direct.c
> +++ b/fs/nfs/direct.c
> @@ -45,6 +45,7 @@
> #include <linux/pagemap.h>
> #include <linux/kref.h>
> #include <linux/slab.h>
> +#include <linux/task_io_accounting_ops.h>
> 
> #include <linux/nfs_fs.h>
> #include <linux/nfs_page.h>
> @@ -939,8 +940,10 @@ ssize_t nfs_file_direct_read(struct kiocb *iocb, const struct iovec *iov,
> 		goto out;
> 
> 	retval = nfs_direct_read(iocb, iov, nr_segs, pos);
> -	if (retval > 0)
> +	if (retval > 0) {
> 		iocb->ki_pos = pos + retval;
> +		task_io_account_read(retval);
> +	}
> 
> out:
> 	return retval;
> @@ -1001,8 +1004,10 @@ ssize_t nfs_file_direct_write(struct kiocb *iocb, const struct iovec *iov,
> 
> 	retval = nfs_direct_write(iocb, iov, nr_segs, pos, count);
> 
> -	if (retval > 0)
> +	if (retval > 0) {
> 		iocb->ki_pos = pos + retval;
> +		task_io_account_write(retval);
> +	}

The async path always returns -EIOCBQUEUED.  How are those bytes accounted for?

> 
> out:
> 	return retval;

--
Chuck Lever
chuck[dot]lever[at]oracle[dot]com