Re: [PATCH 1/2 V1] [PATCH] fs/block-dev.c:fix performance regression in O_DIRECT writes to md block devices

[NeilBrown <neilb@suse.de>]

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On Mon, 16 Jul 2012 14:22:03 +0800 majianpeng <majianpeng@gmail.com> wrote:

> For regular file, write operaion used blk_plug function.But for block
> file,write operation did not use blk_plug.
> This patch is also for write-cache mode for block-device.
> 
> Signed-off-by: Jianpeng Ma <majianpeng@gmail.com>

Reviewed-by: NeilBrown <neilb@suse.de>

Will you take this Jens?  Though mail to you seem to be bouncing:

<axboe@fusionio.com>: host mail.fusionio.com[10.101.1.19] said: 554 5.4.6 Hop
    count exceeded - possible mail loop (in reply to end of DATA command)

so I'm not sure you'll even see this :-(

NeilBrown

> ---
>  fs/block_dev.c |    3 +++
>  1 files changed, 3 insertions(+), 0 deletions(-)
> 
> diff --git a/fs/block_dev.c b/fs/block_dev.c
> index c2bbe1f..cf10778 100644
> --- a/fs/block_dev.c
> +++ b/fs/block_dev.c
> @@ -1579,9 +1579,11 @@ ssize_t blkdev_aio_write(struct kiocb *iocb, const struct iovec *iov,
>  {
>  	struct file *file = iocb->ki_filp;
>  	ssize_t ret;
> +	struct blk_plug plug;
>  
>  	BUG_ON(iocb->ki_pos != pos);
>  
> +	blk_start_plug(&plug);
>  	ret = __generic_file_aio_write(iocb, iov, nr_segs, &iocb->ki_pos);
>  	if (ret > 0 || ret == -EIOCBQUEUED) {
>  		ssize_t err;
> @@ -1590,6 +1592,7 @@ ssize_t blkdev_aio_write(struct kiocb *iocb, const struct iovec *iov,
>  		if (err < 0 && ret > 0)
>  			ret = err;
>  	}
> +	blk_finish_plug(&plug);
>  	return ret;
>  }
>  EXPORT_SYMBOL_GPL(blkdev_aio_write);


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