Re: [PATCH 1/2] block: introduce BIO_IN_FLIGHT flag

From: Namhyung Kim
Date: Tue Jan 10 2012 - 00:07:08 EST


Hi,

2012-01-10 1:41 AM, Tejun Heo wrote:
Hello,

On Mon, Jan 09, 2012 at 11:57:43AM +0900, Namhyung Kim wrote:
I understand your concerns. However, the blktrace cannot get
bio->bi_flags info in its current form AFAIK. Doing it will require
extending struct blk_io_trace and it'll cause a compatibility issue,
I guess.

Umm? Why can't blk_add_trace_bio_complete() look at the flags (or
whatever other states) to decide to fire off BLK_TA_COMPLETE or not?
What's the difference? No userland visible change is necessary at
all. Just make blktrace.c do the right thing. Am I missing
something?

Thanks.


Oh I misunderstood what you said. I was thinking about filtering in pure userspace, but you meant in-kernel probe side.

Right, we can change the probe to filter BIO_BOUNCED case out. But IMHO BIO_CLONED is different, since it usually routed to another device as a separate IO request. I'll cook a patch for the former soon.

Thanks for the comment.
Namhyung Kim
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