block: Convert some code to bio_for_each_segment_all()

More prep work for immutable bvecs:

A few places in the code were either open coding or using the wrong
version - fix.

After we introduce the bvec iter, it'll no longer be possible to modify
the biovec through bio_for_each_segment_all() - it doesn't increment a
pointer to the current bvec, you pass in a struct bio_vec (not a
pointer) which is updated with what the current biovec would be (taking
into account bi_bvec_done and bi_size).

So because of that it's more worthwhile to be consistent about
bio_for_each_segment()/bio_for_each_segment_all() usage.

Signed-off-by: Kent Overstreet <koverstreet@google.com>
CC: Jens Axboe <axboe@kernel.dk>
CC: NeilBrown <neilb@suse.de>
CC: Alasdair Kergon <agk@redhat.com>
CC: dm-devel@redhat.com
CC: Alexander Viro <viro@zeniv.linux.org.uk>

2 files changed, 4 insertions, 9 deletions

diff --git a/drivers/md/dm-crypt.c b/drivers/md/dm-crypt.c
index 13c15480d940..6d2d41ae9e32 100644
--- a/drivers/md/dm-crypt.c
+++ b/drivers/md/dm-crypt.c
@@ -858,8 +858,7 @@ static void crypt_free_buffer_pages(struct crypt_config *cc, struct bio *clone)
         unsigned int i;
         struct bio_vec *bv;
 
-        for (i = 0; i < clone->bi_vcnt; i++) {
-                bv = bio_iovec_idx(clone, i);
+        bio_for_each_segment_all(bv, clone, i) {
                 BUG_ON(!bv->bv_page);
                 mempool_free(bv->bv_page, cc->page_pool);
                 bv->bv_page = NULL;
diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
index 853482015d3d..a7ea954abe1d 100644
--- a/drivers/md/raid1.c
+++ b/drivers/md/raid1.c
@@ -925,7 +925,7 @@ static void alloc_behind_pages(struct bio *bio, struct r1bio *r1_bio)
         if (unlikely(!bvecs))
                 return;
 
-        bio_for_each_segment(bvec, bio, i) {
+        bio_for_each_segment_all(bvec, bio, i) {
                 bvecs[i] = *bvec;
                 bvecs[i].bv_page = alloc_page(GFP_NOIO);
                 if (unlikely(!bvecs[i].bv_page))
@@ -1284,12 +1284,8 @@ read_again:
                         struct bio_vec *bvec;
                         int j;
 
-                        /* Yes, I really want the '__' version so that
-                         * we clear any unused pointer in the io_vec, rather
-                         * than leave them unchanged.  This is important
-                         * because when we come to free the pages, we won't
-                         * know the original bi_idx, so we just free
-                         * them all
+                        /*
+                         * We trimmed the bio, so _all is legit
                          */
                         bio_for_each_segment_all(bvec, mbio, j)
                                 bvec->bv_page = r1_bio->behind_bvecs[j].bv_page;