Re: [PATCH 0/9] Prep work for immutable bio vecs

From: Kent Overstreet
Date: Sun Sep 09 2012 - 21:22:00 EST

On Sat, Sep 08, 2012 at 12:41:15PM -0700, Tejun Heo wrote:
> Hello, Kent.
> On Fri, Sep 07, 2012 at 03:59:11PM -0700, Kent Overstreet wrote:
> > Random assortment of refactoring and trivial cleanups.
> >
> > Immutable bio vecs and efficient bio splitting require auditing and removing
> > pretty much all bi_idx uses, among other things.
> >
> > The reason is that with immutable bio vecs we can't use the bvec array
> > directly; if we have a partially completed bvec, that'll be indicated with a
> > field in struct bvec_iter (which gets embedded in struct bio) - bi_bvec_done.
> >
> > bio_for_each_segments() will handle this transparently, so code needs to be
> > converted to use it or some other generic accessor.
> >
> > Also, bio splitting means that when a driver gets a bio, bi_idx and
> > bi_bvec_done may both be nonzero. Again, just need to use generic accessors.
> There are three pending patchsets and I don't know how they're
> supposed to come together. Please explain on which tree the patches
> are based and how they stack and preferably provide a git branch.

Both of the new ones depend on the block cleanups series, but they
shouldn't depend on each other (bar perhaps some trivial merge
conflicts in bio.h)

Git repo - block_stuff branch on
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