[PATCH v3 16/49] block: bounce: don't access bio->bi_io_vec in copy_to_high_bio_irq

[Ming Lei]

As we need to support multipage bvecs, so don't access bio->bi_io_vec
in copy_to_high_bio_irq(), and just use the standard iterator
to do that.

Signed-off-by: Ming Lei <ming....@redhat.com>
---
 block/bounce.c | 16 +++++++++++-----
 1 file changed, 11 insertions(+), 5 deletions(-)

diff --git a/block/bounce.c b/block/bounce.c
index e57cf2bdcd27..50e965a15295 100644
--- a/block/bounce.c
+++ b/block/bounce.c
@@ -112,24 +112,30 @@ int init_emergency_isa_pool(void)
 static void copy_to_high_bio_irq(struct bio *to, struct bio *from)
 {
        unsigned char *vfrom;
-       struct bio_vec tovec, *fromvec = from->bi_io_vec;
+       struct bio_vec tovec, fromvec;
        struct bvec_iter iter;
+       /*
+        * The bio of @from is created by bounce, so we can iterate
+        * its bvec from start to end, but the @from->bi_iter can't be
+        * trusted because it might be changed by splitting.
+        */
+       struct bvec_iter from_iter = BVEC_ITER_ALL_INIT;
 
        bio_for_each_segment(tovec, to, iter) {
-               if (tovec.bv_page != fromvec->bv_page) {
+               fromvec = bio_iter_iovec(from, from_iter);
+               if (tovec.bv_page != fromvec.bv_page) {
                        /*
                         * fromvec->bv_offset and fromvec->bv_len might have
                         * been modified by the block layer, so use the original
                         * copy, bounce_copy_vec already uses tovec->bv_len
                         */
-                       vfrom = page_address(fromvec->bv_page) +
+                       vfrom = page_address(fromvec.bv_page) +
                                tovec.bv_offset;
 
                        bounce_copy_vec(&tovec, vfrom);
                        flush_dcache_page(tovec.bv_page);
                }
-
-               fromvec++;
+               bio_advance_iter(from, &from_iter, tovec.bv_len);
        }
 }
 
-- 
2.9.4