[PATCH 3.16 100/204] more bio_map_user_iov() leak fixes

[Ben Hutchings]

3.16.52-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Al Viro <v...@zeniv.linux.org.uk>

commit 2b04e8f6bbb196cab4b232af0f8d48ff2c7a8058 upstream.

we need to take care of failure exit as well - pages already
in bio should be dropped by analogue of bio_unmap_pages(),
since their refcounts had been bumped only once per reference
in bio.

Signed-off-by: Al Viro <v...@zeniv.linux.org.uk>
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings <b...@decadent.org.uk>
---
 block/bio.c | 14 +++++++++-----
 1 file changed, 9 insertions(+), 5 deletions(-)

--- a/block/bio.c
+++ b/block/bio.c
@@ -1286,6 +1286,7 @@ static struct bio *__bio_map_user_iov(st
        struct bio *bio;
        int cur_page = 0;
        int ret, offset;
+       struct bio_vec *bvec;
 
        for (i = 0; i < iov_count; i++) {
                unsigned long uaddr = (unsigned long)iov[i].iov_base;
@@ -1329,7 +1330,12 @@ static struct bio *__bio_map_user_iov(st
 
                ret = get_user_pages_fast(uaddr, local_nr_pages,
                                write_to_vm, &pages[cur_page]);
-               if (ret < local_nr_pages) {
+               if (unlikely(ret < local_nr_pages)) {
+                       for (j = cur_page; j < page_limit; j++) {
+                               if (!pages[j])
+                                       break;
+                               put_page(pages[j]);
+                       }
                        ret = -EFAULT;
                        goto out_unmap;
                }
@@ -1384,10 +1390,8 @@ static struct bio *__bio_map_user_iov(st
        return bio;
 
  out_unmap:
-       for (i = 0; i < nr_pages; i++) {
-               if(!pages[i])
-                       break;
-               page_cache_release(pages[i]);
+       bio_for_each_segment_all(bvec, bio, j) {
+               put_page(bvec->bv_page);
        }
  out:
        kfree(pages);