Re: [PATCH 0/7] Discard requests, v2

[OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>]

Jamie Lokier <jamie@shareable.org> writes:

> David Woodhouse wrote:
>> > 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.

[...]

> you wouldn't want them to affect latency-sensitive READ.

Yes. My concern is like it. If it's READ and it's passed to device
immediately like sync, I guess there is impact to userland throughput.

[...]

@@ -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;

Or another options is caller should do? e.g. (WRITE | (1 << BIO_RW_DISCARD))
-- 
OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>