Messages in this thread | | | Date | Thu, 9 Aug 2012 00:01:54 -0700 | From | Tejun Heo <> | Subject | Re: [dm-devel] [PATCH v5 12/12] block: Only clone bio vecs that are in use |
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Hello,
On Wed, Aug 08, 2012 at 04:47:46PM -0700, Muthu Kumar wrote: > You are changing the meaning of __bio_clone() here. In old code, the > number of io_vecs, bi_idx, bi_vcnt are preserved. But in this modified > code, you are mapping bio_src's bi_iovec[bi_idx] to bio_dests > bi_iovec[0] and also restricting the number of allocated io_vecs of > the clone. It may be useful for cases were we would like a identical > copy of the original bio (may not be in current code base, but this > implementation is definitely not what one would expect from the name > "clone").
Implementation details changed somewhat but the high-level semantics didn't change at all. Any driver not messing with bio internals - and they shouldn't - shouldn't notice the change. No in-kernel drivers seem to be broken by the change. If you ask me, this looks more like a bug fix to me where the bug is a silly behavior restricting usefulness of the interface.
> May be, call this new implementation some thing else (and use it for bcache)?
This doesn't only change __bio_clone() but all clone interface stacked on top of it, so, no way. This ain't windows.
Thanks.
-- tejun
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