Re: [PATCH 42/41] dm: convey that all flushes are processed as empty

From: Christoph Hellwig
Date: Tue Sep 07 2010 - 20:00:48 EST


On Tue, Sep 07, 2010 at 07:49:18PM -0400, Mike Snitzer wrote:
> if (!(bio->bi_rw & REQ_FLUSH) || !bio->bi_size) {
> + /* done with normal IO or empty flush */
> trace_block_bio_complete(md->queue, bio);
> bio_endio(bio, io_error);
> } else {

To clarify this further I'd reorder the checks:

if ((bio->bi_rw & REQ_FLUSH) && bio->bi_size) {
/*
* Preflush done, ...
*/
} else {
}

> @@ -1302,20 +1302,17 @@ static void __split_and_process_bio(struct mapped_device *md, struct bio *bio)
> ci.sector = bio->bi_sector;
> ci.idx = bio->bi_idx;
>
> + start_io_acct(ci.io);
> if (!is_flush) {

no need for the is_flush anymore now that it's only used once. Again,
I think avoiding negatives without a reason in if statement usually
makes the code a bit more clear.

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