On Sat, 2008-02-09 at 10:40 +0900, Tejun Heo wrote:
> Clear drain buffer before chaining if the command in question is a
> write.
>
> Signed-off-by: Tejun Heo <htejun@xxxxxxxxx>
> ---
> block/blk-merge.c | 3 +++
> 1 files changed, 3 insertions(+), 0 deletions(-)
>
> diff --git a/block/blk-merge.c b/block/blk-merge.c
> index d50cfc8..d0b9031 100644
> --- a/block/blk-merge.c
> +++ b/block/blk-merge.c
> @@ -221,6 +221,9 @@ new_segment:
> } /* segments in rq */
>
> if (q->dma_drain_size && q->dma_drain_needed(rq)) {
> + if (rq->cmd_flags & REQ_RW)
> + memset(q->dma_drain_buffer, 0, q->dma_drain_size);
> +
This is a bit performance impacting, isn't it? If you're worried about
data security from a read overrun, then you could do a lazy clear on
read completion if the overrun was used (i.e. if there's any residual).
James
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