diff options
| -rw-r--r-- | fs/bio.c | 60 |
1 files changed, 47 insertions, 13 deletions
@@ -549,36 +549,70 @@ void __bio_clone(struct bio *bio, struct bio *bio_src) EXPORT_SYMBOL(__bio_clone); /** - * bio_clone_bioset - clone a bio - * @bio: bio to clone + * bio_clone_bioset - clone a bio + * @bio_src: bio to clone * @gfp_mask: allocation priority * @bs: bio_set to allocate from * - * Like __bio_clone, only also allocates the returned bio + * Clone bio. Caller will own the returned bio, but not the actual data it + * points to. Reference count of returned bio will be one. */ -struct bio *bio_clone_bioset(struct bio *bio, gfp_t gfp_mask, +struct bio *bio_clone_bioset(struct bio *bio_src, gfp_t gfp_mask, struct bio_set *bs) { - struct bio *b; + unsigned nr_iovecs = 0; + struct bvec_iter iter; + struct bio_vec bv; + struct bio *bio; + + /* + * Pre immutable biovecs, __bio_clone() used to just do a memcpy from + * bio_src->bi_io_vec to bio->bi_io_vec. + * + * We can't do that anymore, because: + * + * - The point of cloning the biovec is to produce a bio with a biovec + * the caller can modify: bi_idx and bi_bvec_done should be 0. + * + * - The original bio could've had more than BIO_MAX_PAGES biovecs; if + * we tried to clone the whole thing bio_alloc_bioset() would fail. + * But the clone should succeed as long as the number of biovecs we + * actually need to allocate is fewer than BIO_MAX_PAGES. + * + * - Lastly, bi_vcnt should not be looked at or relied upon by code + * that does not own the bio - reason being drivers don't use it for + * iterating over the biovec anymore, so expecting it to be kept up + * to date (i.e. for clones that share the parent biovec) is just + * asking for trouble and would force extra work on + * __bio_clone_fast() anyways. + */ + + bio_for_each_segment(bv, bio_src, iter) + nr_iovecs++; - b = bio_alloc_bioset(gfp_mask, bio->bi_max_vecs, bs); - if (!b) + bio = bio_alloc_bioset(gfp_mask, nr_iovecs, bs); + if (!bio) return NULL; - __bio_clone(b, bio); + bio->bi_bdev = bio_src->bi_bdev; + bio->bi_rw = bio_src->bi_rw; + bio->bi_iter.bi_sector = bio_src->bi_iter.bi_sector; + bio->bi_iter.bi_size = bio_src->bi_iter.bi_size; - if (bio_integrity(bio)) { - int ret; + bio_for_each_segment(bv, bio_src, iter) + bio->bi_io_vec[bio->bi_vcnt++] = bv; - ret = bio_integrity_clone(b, bio, gfp_mask); + if (bio_integrity(bio_src)) { + int ret; + ret = bio_integrity_clone(bio, bio_src, gfp_mask); if (ret < 0) { - bio_put(b); + bio_put(bio); return NULL; } } - return b; + return bio; } EXPORT_SYMBOL(bio_clone_bioset); |