linux-kernel - Re: [PATCH] blk: missing add of padded bytes to io completion byte count

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Date:	Wed, 05 Mar 2008 13:28:50 +0100
From:	Mike Galbraith <efault@....de>
To:	Boaz Harrosh <bharrosh@...asas.com>
Cc:	FUJITA Tomonori <fujita.tomonori@....ntt.co.jp>,
	Tejun Heo <htejun@...il.com>, jens.axboe@...cle.com,
	James.Bottomley@...senPartnership.com, tomof@....org,
	akpm@...ux-foundation.org, linux-kernel@...r.kernel.org,
	linux-ide@...r.kernel.org, linux-scsi@...r.kernel.org,
	jgarzik@...ox.com, bzolnier@...il.com
Subject: Re: [PATCH] blk: missing add of padded bytes to io completion byte
	count


On Wed, 2008-03-05 at 12:16 +0200, Boaz Harrosh wrote:

> Please test it solves the CD burning problem.

Works for me.

	-Mike

> (The patch includes the revert of commit e97a294e)
> ---
> From: Boaz Harrosh <bharrosh@...asas.com>
> Date: Wed, 5 Mar 2008 12:07:12 +0200
> Subject: [PATCH] blk: missing add of padded bytes to io completion byte count
> 
> the commit e97a294ef6938512b655b1abf17656cf2b26f709 was very wrong. This is
> because scsi-ml supports the ability to split a request into smaller chunks,
> in which case scsi_bufflen() is smaller then request length. Then at completion
> time the remainder can be issued as a new scsi command. In that case the above
> commit is a data corruption.
> 
> Also in this fix all users of block layer are taken care of, and not only
> scsi devices.
> 
> Signed-off-by: Boaz Harrosh <bharrosh@...asas.com>
> Signed-off-by: Benny Halevy <bhalevy@...asas.com>
> ---
>  block/blk-core.c    |    4 ++++
>  drivers/scsi/scsi.c |    2 +-
>  2 files changed, 5 insertions(+), 1 deletions(-)
> 
> diff --git a/block/blk-core.c b/block/blk-core.c
> index 2a438a9..37fcccc 100644
> --- a/block/blk-core.c
> +++ b/block/blk-core.c
> @@ -1549,6 +1549,9 @@ static int __end_that_request_first(struct request *req, int error,
>  			     nr_bytes >> 9, req->sector);
>  	}
>  
> +	if (nr_bytes >= blk_rq_bytes(req))
> +		nr_bytes += req->extra_len;
> +
>  	total_bytes = bio_nbytes = 0;
>  	while ((bio = req->bio) != NULL) {
>  		int nbytes;
> @@ -1616,6 +1619,7 @@ static int __end_that_request_first(struct request *req, int error,
>  	if (!req->bio)
>  		return 0;
>  
> +	BUG_ON(total_bytes >= blk_rq_bytes(req));
>  	/*
>  	 * if the request wasn't completed, update state
>  	 */
> diff --git a/drivers/scsi/scsi.c b/drivers/scsi/scsi.c
> index e5c6f6a..fecba05 100644
> --- a/drivers/scsi/scsi.c
> +++ b/drivers/scsi/scsi.c
> @@ -757,7 +757,7 @@ void scsi_finish_command(struct scsi_cmnd *cmd)
>  				"Notifying upper driver of completion "
>  				"(result %x)\n", cmd->result));
>  
> -	good_bytes = scsi_bufflen(cmd) + cmd->request->extra_len;
> +	good_bytes = scsi_bufflen(cmd);
>          if (cmd->request->cmd_type != REQ_TYPE_BLOCK_PC) {
>  		drv = scsi_cmd_to_driver(cmd);
>  		if (drv->done)

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