[SCSI] block: fix bio_add_page misuse with rq_map_data

This fixes bio_add_page misuse in bio_copy_user_iov with rq_map_data,
which only sg uses now.

rq_map_data carries page frames for bio_add_pc_page. bio_copy_user_iov
uses bio_add_pc_page with a larger size than PAGE_SIZE. It's clearly
wrong.

Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Acked-by: Jens Axboe <jens.axboe@oracle.com>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>

1 files changed, 14 insertions, 12 deletions

diff --git a/fs/bio.c b/fs/bio.c
index 711cee103602..356e7423b923 100644
--- a/fs/bio.c
+++ b/fs/bio.c
@@ -815,28 +815,30 @@ struct bio *bio_copy_user_iov(struct request_queue *q,
 
         ret = 0;
         i = 0;
+        if (map_data)
+                nr_pages = 1 << map_data->page_order;
         while (len) {
-                unsigned int bytes;
-
-                if (map_data)
-                        bytes = 1U << (PAGE_SHIFT + map_data->page_order);
-                else
-                        bytes = PAGE_SIZE;
+                unsigned int bytes = PAGE_SIZE;
 
                 if (bytes > len)
                         bytes = len;
 
                 if (map_data) {
-                        if (i == map_data->nr_entries) {
+                        if (i == map_data->nr_entries * nr_pages) {
                                 ret = -ENOMEM;
                                 break;
                         }
-                        page = map_data->pages[i++];
-                } else
+
+                        page = map_data->pages[i / nr_pages];
+                        page += (i % nr_pages);
+
+                        i++;
+                } else {
                         page = alloc_page(q->bounce_gfp | gfp_mask);
-                if (!page) {
-                        ret = -ENOMEM;
-                        break;
+                        if (!page) {
+                                ret = -ENOMEM;
+                                break;
+                        }
                 }
 
                 if (bio_add_pc_page(q, bio, page, bytes, 0) < bytes)