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 <mwilck@xxxxxxxx>
---
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
