bio_copy_user_iov(): don't ignore ->iov_offset

commit 1cfd0ddd82232804e03f3023f6a58b50dfef0574 upstream.

Since "block: support large requests in blk_rq_map_user_iov" we
started to call it with partially drained iter; that works fine
on the write side, but reads create a copy of iter for completion
time.  And that needs to take the possibility of ->iov_iter != 0
into account...

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/block/bio.c b/block/bio.c
index cbf2db1..07f287b 100644 (file)
--- a/block/bio.c
+++ b/block/bio.c
@@ -1171,8 +1171,8 @@ struct bio *bio_copy_user_iov(struct request_queue *q,
         */
        bmd->is_our_pages = map_data ? 0 : 1;
        memcpy(bmd->iov, iter->iov, sizeof(struct iovec) * iter->nr_segs);
-       iov_iter_init(&bmd->iter, iter->type, bmd->iov,
-                       iter->nr_segs, iter->count);
+       bmd->iter = *iter;
+       bmd->iter.iov = bmd->iov;
 
        ret = -ENOMEM;
        bio = bio_kmalloc(gfp_mask, nr_pages);