[dm-devel] [PATCH v6 13/13] block: Only clone bio vecs that are in use
Tejun Heo
tj at kernel.org
Wed Aug 22 21:10:45 UTC 2012
Hello, Kent.
On Wed, Aug 22, 2012 at 10:04:10AM -0700, Kent Overstreet wrote:
> bcache creates large bios internally, and then splits them according to
> the device requirements before it sends them down. If a lower level
> device tries to clone the bio, and the original bio had more than
> BIO_MAX_PAGES, the clone will fail unecessarily.
>
> We can fix this by only cloning the bio vecs that are actually in use.
I'm pretty sure I sound like a broken record by now, but
* How was this tested?
* What are the implications and possible dangers?
> @@ -463,10 +468,10 @@ void __bio_clone(struct bio *bio, struct bio *bio_src)
> bio->bi_sector = bio_src->bi_sector;
> bio->bi_bdev = bio_src->bi_bdev;
> bio->bi_flags |= 1 << BIO_CLONED;
> + bio->bi_flags &= ~(1 << BIO_SEG_VALID);
For the n'th time, explain please.
Thanks.
--
tejun
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