bio_iov_iter_get_pages() only adds pages for the next non-zero segment from the iov_iter to the bio. Some callers prefer to obtain as many pages as would fit into the bio, with proper rollback in case of failure. Add bio_iov_iter_get_all_pages() for this purpose.
Signed-off-by: Martin Wilck <[email protected]> --- block/bio.c | 43 ++++++++++++++++++++++++++++++++++++++++++- include/linux/bio.h | 1 + 2 files changed, 43 insertions(+), 1 deletion(-) diff --git a/block/bio.c b/block/bio.c index 489a430..693eb3b 100644 --- a/block/bio.c +++ b/block/bio.c @@ -907,8 +907,10 @@ EXPORT_SYMBOL(bio_add_page); * @bio: bio to add pages to * @iter: iov iterator describing the region to be mapped * - * Pins as many pages from *iter and appends them to @bio's bvec array. The + * Pins pages from *iter and appends them to @bio's bvec array. The * pages will have to be released using put_page() when done. + * For multi-segment *iter, this function only adds pages from the + * the next non-empty segment of the iov iterator. */ int bio_iov_iter_get_pages(struct bio *bio, struct iov_iter *iter) { @@ -949,6 +951,45 @@ int bio_iov_iter_get_pages(struct bio *bio, struct iov_iter *iter) } EXPORT_SYMBOL_GPL(bio_iov_iter_get_pages); +/** + * bio_iov_iter_get_all_pages - pin user or kernel pages and add them to a bio + * @bio: bio to add pages to + * @iter: iov iterator describing the region to be mapped + * + * Pins pages from *iter and appends them to @bio's bvec array. The + * pages will have to be released using put_page() when done. + * This function adds as many pages as possible to a bio. + * If this function encounters an error, it unpins the pages it has + * pinned before, leaving previously pinned pages untouched. + */ +int bio_iov_iter_get_all_pages(struct bio *bio, struct iov_iter *iter) +{ + unsigned short orig_vcnt = bio->bi_vcnt; + + do { + int ret = bio_iov_iter_get_pages(bio, iter); + + if (unlikely(ret)) { + struct bio_vec *bvec; + unsigned short i; + + bio_for_each_segment_all(bvec, bio, i) { + if (i >= orig_vcnt) { + put_page(bvec->bv_page); + bvec->bv_page = NULL; + bvec->bv_len = 0; + bvec->bv_offset = 0; + } + } + bio->bi_vcnt = orig_vcnt; + return ret; + } + } while (iov_iter_count(iter) && !bio_full(bio)); + + return 0; +} +EXPORT_SYMBOL_GPL(bio_iov_iter_get_all_pages); + static void submit_bio_wait_endio(struct bio *bio) { complete(bio->bi_private); diff --git a/include/linux/bio.h b/include/linux/bio.h index f08f5fe..824cb74 100644 --- a/include/linux/bio.h +++ b/include/linux/bio.h @@ -485,6 +485,7 @@ bool __bio_try_merge_page(struct bio *bio, struct page *page, void __bio_add_page(struct bio *bio, struct page *page, unsigned int len, unsigned int off); int bio_iov_iter_get_pages(struct bio *bio, struct iov_iter *iter); +int bio_iov_iter_get_all_pages(struct bio *bio, struct iov_iter *iter); struct rq_map_data; extern struct bio *bio_map_user_iov(struct request_queue *, struct iov_iter *, gfp_t); -- 2.17.1
