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rbd: Refactor bio cloning

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Now that we've got drivers converted to the new immutable bvec
primitives, bio splitting becomes much easier - this is how the new
bio_split() will work. (Someone more familiar with the ceph code could
probably use bio_clone_fast() instead of bio_clone() here).

Signed-off-by: Kent Overstreet <kmo@daterainc.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Yehuda Sadeh <yehuda@inktank.com>
Cc: Alex Elder <elder@inktank.com>
Cc: ceph-devel@vger.kernel.org
This commit is contained in:
Kent Overstreet 2013-08-07 14:31:11 -07:00
parent 59d276fe02
commit 5341a6278b
1 changed files with 2 additions and 62 deletions
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64
drivers/block/rbd.c
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@ -1173,73 +1173,13 @@ static struct bio *bio_clone_range(struct bio *bio_src,
unsigned int len,
gfp_t gfpmask)
{
struct bio_vec bv;
struct bvec_iter iter;
struct bvec_iter end_iter;
unsigned int resid;
unsigned int voff;
unsigned short vcnt;
struct bio *bio;
/* Handle the easy case for the caller */
if (!offset && len == bio_src->bi_iter.bi_size)
return bio_clone(bio_src, gfpmask);
if (WARN_ON_ONCE(!len))
return NULL;
if (WARN_ON_ONCE(len > bio_src->bi_iter.bi_size))
return NULL;
if (WARN_ON_ONCE(offset > bio_src->bi_iter.bi_size - len))
return NULL;
/* Find first affected segment... */
resid = offset;
bio_for_each_segment(bv, bio_src, iter) {
if (resid < bv.bv_len)
break;
resid -= bv.bv_len;
}
voff = resid;
/* ...and the last affected segment */
resid += len;
__bio_for_each_segment(bv, bio_src, end_iter, iter) {
if (resid <= bv.bv_len)
break;
resid -= bv.bv_len;
}
vcnt = end_iter.bi_idx = iter.bi_idx + 1;
/* Build the clone */
bio = bio_alloc(gfpmask, (unsigned int) vcnt);
bio = bio_clone(bio_src, gfpmask);
if (!bio)
return NULL; /* ENOMEM */
bio->bi_bdev = bio_src->bi_bdev;
bio->bi_iter.bi_sector = bio_src->bi_iter.bi_sector +
(offset >> SECTOR_SHIFT);
bio->bi_rw = bio_src->bi_rw;
bio->bi_flags |= 1 << BIO_CLONED;
/*
* Copy over our part of the bio_vec, then update the first
* and last (or only) entries.
*/
memcpy(&bio->bi_io_vec[0], &bio_src->bi_io_vec[iter.bi_idx],
vcnt * sizeof (struct bio_vec));
bio->bi_io_vec[0].bv_offset += voff;
if (vcnt > 1) {
bio->bi_io_vec[0].bv_len -= voff;
bio->bi_io_vec[vcnt - 1].bv_len = resid;
} else {
bio->bi_io_vec[0].bv_len = len;
}
bio->bi_vcnt = vcnt;
bio_advance(bio, offset);
bio->bi_iter.bi_size = len;
return bio;