Messages in this thread | | | Date | Thu, 2 Aug 2007 01:21:45 +0900 | From | Tejun Heo <> | Subject | Re: [PATCH 019 of 35] Convert bio_for_each_segment to fill in a fresh bio_vec |
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Hi,
On Tue, Jul 31, 2007 at 12:17:27PM +1000, NeilBrown wrote: > i.e. instread of providing a pointer to each bio_vec, it provides > a copy of each bio_vec. > > This allows a future patch to cause bio_for_each_segment to > provide bio_vecs that are not in the bi_io_vec list, thus allowing > for offsets and length restrictions. > > We consequently remove the only call for bio_kmap_atomic, > and so remove that function as well. > Also remove bio_kmap_irq. No-one uses it, and bvec_kmap_irq > is a much more usable interface.
I think this patch can be split into two but it's no big deal.
> +struct bio_iterator { > + int i; > +}; > #define bio_for_each_segment(bvl, bio, i) \ > - for (bvl = bio_iovec_idx((bio), 0), i = 0; \ > - i < (bio)->bi_vcnt; \ > - bvl++, i++) > + for (i.i = 0, bvl = *bio_iovec_idx((bio), i.i); \ > + i.i < (bio)->bi_vcnt; \ > + i.i++, bvl = *bio_iovec_idx((bio), i.i))
How about something like...
struct bio_iterator { int i; struct bio_vec tmp_bvec; /* might put bio here too? */ };
#define bio_for_each_segment(bvl, bio, i) \ for (bvl = bio_iter_init(&i, bio); i.i < (bio)->bi_vcnt; \ bvl = bio_iter_next(&i, bio))
[static inline] struct bio_vec *bio_iter_init(struct bio_iterator *i, struct bio *bio) { i->i = 0;
if (no further restrictions) return bio_iovec_idx(bio, 0); else { i->tmp_bvec = *bio_iovec_idx(bio, 0); apply restriction; return &i->tmp_bvec; } }
[static inline] struct bio_vec *bio_iter_next(struct bio_iterator *i, struct bio *bio) { i->i++;
if (no further restriction) return bio_iovec_idx(bio, i->i); else { i->tmp_bvec = *bio_iovec_idx(bio, i->i); apply restriction; return &i->tmp_bvec; } }
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