On Sun, 2008-08-10 at 07:48 +0900, OGAWA Hirofumi wrote:
> I wonder about I/O schedule impact...
>
> Currently it seems we schedule data direction as READ (no flags).
> Although I'm not sure, we might want to schedule it as WRITE? (I guess
> WRITE can be allowed delay more than READ...)
I'm not sure it matters much -- this is mostly going to be used on
devices which aren't affected by I/O scheduling at all and should
probably be using the no-op scheduler.
But we could do it fairly easily -- we just have to make sure it's done
before blk_alloc_request() shows it to elv_set_request(), which means we
can't just do it in init_request_from_bio() because that's too late.
diff --git a/block/blk-core.c b/block/blk-core.c
index 0c8ed97..b92e8aa 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -1489,6 +1489,8 @@ void submit_bio(int rw, struct bio *bio)
{
int count = bio_sectors(bio);
+ if (rw & (1 << BIO_RW_DISCARD))
+ rw |= WRITE;
bio->bi_rw |= rw;
/*
--
David Woodhouse Open Source Technology Centre
David.Woodhouse@xxxxxxxxx Intel Corporation
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