... and with iov_iter_get_pages_alloc() it becomes even simpler

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

diff --git a/block/bio.c b/block/bio.c
index 5de54de..5dbc5e9 100644 (file)
--- a/block/bio.c
+++ b/block/bio.c
@@ -1325,9 +1325,7 @@ struct bio *bio_map_user_iov(struct request_queue *q,
 {
        int j;
        int nr_pages = 0;
-       struct page **pages;
        struct bio *bio;
-       int cur_page = 0;
        int ret;
        struct iov_iter i;
        struct iovec iov;
@@ -1360,19 +1358,14 @@ struct bio *bio_map_user_iov(struct request_queue *q,
        if (!bio)
                return ERR_PTR(-ENOMEM);
 
-       ret = -ENOMEM;
-       pages = kcalloc(nr_pages, sizeof(struct page *), gfp_mask);
-       if (!pages)
-               goto out;
-
        i = *iter;
        while (iov_iter_count(&i)) {
+               struct page **pages;
                ssize_t bytes;
                size_t offs, added = 0;
                int npages;
 
-               bytes = iov_iter_get_pages(&i, pages + cur_page, LONG_MAX,
-                                               nr_pages - cur_page, &offs);
+               bytes = iov_iter_get_pages_alloc(&i, &pages, LONG_MAX, &offs);
                if (unlikely(bytes <= 0)) {
                        ret = bytes ? bytes : -EFAULT;
                        goto out_unmap;
@@ -1380,7 +1373,7 @@ struct bio *bio_map_user_iov(struct request_queue *q,
 
                npages = DIV_ROUND_UP(offs + bytes, PAGE_SIZE);
 
-               for (j = cur_page; j < cur_page + npages; j++) {
+               for (j = 0; j < npages; j++) {
                        unsigned int n = PAGE_SIZE - offs;
                        unsigned short prev_bi_vcnt = bio->bi_vcnt;
 
@@ -1409,13 +1402,11 @@ struct bio *bio_map_user_iov(struct request_queue *q,
                /*
                 * release the pages we didn't map into the bio, if any
                 */
-               while (j < cur_page + npages)
+               while (j < npages)
                        put_page(pages[j++]);
-               cur_page = j;
+               kvfree(pages);
        }
 
-       kfree(pages);
-
        bio_set_flag(bio, BIO_USER_MAPPED);
 
        /*
@@ -1431,8 +1422,6 @@ struct bio *bio_map_user_iov(struct request_queue *q,
        bio_for_each_segment_all(bvec, bio, j) {
                put_page(bvec->bv_page);
        }
- out:
-       kfree(pages);
        bio_put(bio);
        return ERR_PTR(ret);
 }