On Thursday 24 March 2011, Andrei Warkentin wrote:
> This is a request-for-comments patch. Please provide your feedback.
>
> Allows reliable writes to be used for MMC writes. Reliable writes are used
> to service write REQ_FUA/REQ_META requests. Handles both the legacy and the
> enhanced
> reliable write support in MMC cards.
>
> Beyond REQ_FUA/REQ_META, this was meant to be used by a following patch that
> aimed
> to reduce write amplification issues in cards employing a small (usually
> flash page-sized)
> buffer and a large (usually erase-block sized) buffer, at the expense of
> performance.
Looks good to me, but I don't really understand some of the block layer
specifics here. One question:
> +static int mmc_blk_issue_flush(struct mmc_queue *mq, struct request *req)
> +{
> + struct mmc_blk_data *md = mq->data;
> +
> + /*
> + No-op, only service this because we need REQ_FUA
> + for reliable writes.
> + */
> + spin_lock_irq(&md->lock);
> + __blk_end_request_all(req, 0);
> + spin_unlock_irq(&md->lock);
> +
> + return 1;
> +}
How does this work when you have a flush that does not directly follow
a REQ_FUA or REQ_META request? I would assume that we still need to
flush in some way, which you don't seem to do here.
Arnd
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