block: Convert bio_for_each_segment() to bvec_iter

More prep work for immutable biovecs - with immutable bvecs drivers
won't be able to use the biovec directly, they'll need to use helpers
that take into account bio->bi_iter.bi_bvec_done.

This updates callers for the new usage without changing the
implementation yet.

Signed-off-by: Kent Overstreet <kmo@daterainc.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: "Ed L. Cashin" <ecashin@coraid.com>
Cc: Nick Piggin <npiggin@kernel.dk>
Cc: Lars Ellenberg <drbd-dev@lists.linbit.com>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Paul Clements <Paul.Clements@steeleye.com>
Cc: Jim Paris <jim@jtan.com>
Cc: Geoff Levand <geoff@infradead.org>
Cc: Yehuda Sadeh <yehuda@inktank.com>
Cc: Sage Weil <sage@inktank.com>
Cc: Alex Elder <elder@inktank.com>
Cc: ceph-devel@vger.kernel.org
Cc: Joshua Morris <josh.h.morris@us.ibm.com>
Cc: Philip Kelleher <pjk1939@linux.vnet.ibm.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: Neil Brown <neilb@suse.de>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: linux390@de.ibm.com
Cc: Nagalakshmi Nandigama <Nagalakshmi.Nandigama@lsi.com>
Cc: Sreekanth Reddy <Sreekanth.Reddy@lsi.com>
Cc: support@lsi.com
Cc: "James E.J. Bottomley" <JBottomley@parallels.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Steven Whitehouse <swhiteho@redhat.com>
Cc: Herton Ronaldo Krzesinski <herton.krzesinski@canonical.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Guo Chao <yan@linux.vnet.ibm.com>
Cc: Asai Thambi S P <asamymuthupa@micron.com>
Cc: Selvan Mani <smani@micron.com>
Cc: Sam Bradshaw <sbradshaw@micron.com>
Cc: Matthew Wilcox <matthew.r.wilcox@intel.com>
Cc: Keith Busch <keith.busch@intel.com>
Cc: Stephen Hemminger <shemminger@vyatta.com>
Cc: Quoc-Son Anh <quoc-sonx.anh@intel.com>
Cc: Sebastian Ott <sebott@linux.vnet.ibm.com>
Cc: Nitin Gupta <ngupta@vflare.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Jerome Marchand <jmarchan@redhat.com>
Cc: Seth Jennings <sjenning@linux.vnet.ibm.com>
Cc: "Martin K. Petersen" <martin.petersen@oracle.com>
Cc: Mike Snitzer <snitzer@redhat.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: "Darrick J. Wong" <darrick.wong@oracle.com>
Cc: Chris Metcalf <cmetcalf@tilera.com>
Cc: Jan Kara <jack@suse.cz>
Cc: linux-m68k@lists.linux-m68k.org
Cc: linuxppc-dev@lists.ozlabs.org
Cc: drbd-user@lists.linbit.com
Cc: nbd-general@lists.sourceforge.net
Cc: cbe-oss-dev@lists.ozlabs.org
Cc: xen-devel@lists.xensource.com
Cc: virtualization@lists.linux-foundation.org
Cc: linux-raid@vger.kernel.org
Cc: linux-s390@vger.kernel.org
Cc: DL-MPTFusionLinux@lsi.com
Cc: linux-scsi@vger.kernel.org
Cc: devel@driverdev.osuosl.org
Cc: linux-fsdevel@vger.kernel.org
Cc: cluster-devel@redhat.com
Cc: linux-mm@kvack.org
Acked-by: Geoff Levand <geoff@infradead.org>
diff --git a/drivers/s390/block/dasd_fba.c b/drivers/s390/block/dasd_fba.c
index 9cbc8c3..2c8e68b 100644
--- a/drivers/s390/block/dasd_fba.c
+++ b/drivers/s390/block/dasd_fba.c
@@ -260,7 +260,7 @@
 	struct dasd_ccw_req *cqr;
 	struct ccw1 *ccw;
 	struct req_iterator iter;
-	struct bio_vec *bv;
+	struct bio_vec bv;
 	char *dst;
 	int count, cidaw, cplength, datasize;
 	sector_t recid, first_rec, last_rec;
@@ -283,13 +283,13 @@
 	count = 0;
 	cidaw = 0;
 	rq_for_each_segment(bv, req, iter) {
-		if (bv->bv_len & (blksize - 1))
+		if (bv.bv_len & (blksize - 1))
 			/* Fba can only do full blocks. */
 			return ERR_PTR(-EINVAL);
-		count += bv->bv_len >> (block->s2b_shift + 9);
+		count += bv.bv_len >> (block->s2b_shift + 9);
 #if defined(CONFIG_64BIT)
-		if (idal_is_needed (page_address(bv->bv_page), bv->bv_len))
-			cidaw += bv->bv_len / blksize;
+		if (idal_is_needed (page_address(bv.bv_page), bv.bv_len))
+			cidaw += bv.bv_len / blksize;
 #endif
 	}
 	/* Paranoia. */
@@ -326,16 +326,16 @@
 	}
 	recid = first_rec;
 	rq_for_each_segment(bv, req, iter) {
-		dst = page_address(bv->bv_page) + bv->bv_offset;
+		dst = page_address(bv.bv_page) + bv.bv_offset;
 		if (dasd_page_cache) {
 			char *copy = kmem_cache_alloc(dasd_page_cache,
 						      GFP_DMA | __GFP_NOWARN);
 			if (copy && rq_data_dir(req) == WRITE)
-				memcpy(copy + bv->bv_offset, dst, bv->bv_len);
+				memcpy(copy + bv.bv_offset, dst, bv.bv_len);
 			if (copy)
-				dst = copy + bv->bv_offset;
+				dst = copy + bv.bv_offset;
 		}
-		for (off = 0; off < bv->bv_len; off += blksize) {
+		for (off = 0; off < bv.bv_len; off += blksize) {
 			/* Locate record for stupid devices. */
 			if (private->rdc_data.mode.bits.data_chain == 0) {
 				ccw[-1].flags |= CCW_FLAG_CC;
@@ -384,7 +384,7 @@
 	struct dasd_fba_private *private;
 	struct ccw1 *ccw;
 	struct req_iterator iter;
-	struct bio_vec *bv;
+	struct bio_vec bv;
 	char *dst, *cda;
 	unsigned int blksize, off;
 	int status;
@@ -399,8 +399,8 @@
 	if (private->rdc_data.mode.bits.data_chain != 0)
 		ccw++;
 	rq_for_each_segment(bv, req, iter) {
-		dst = page_address(bv->bv_page) + bv->bv_offset;
-		for (off = 0; off < bv->bv_len; off += blksize) {
+		dst = page_address(bv.bv_page) + bv.bv_offset;
+		for (off = 0; off < bv.bv_len; off += blksize) {
 			/* Skip locate record. */
 			if (private->rdc_data.mode.bits.data_chain == 0)
 				ccw++;
@@ -411,7 +411,7 @@
 					cda = (char *)((addr_t) ccw->cda);
 				if (dst != cda) {
 					if (rq_data_dir(req) == READ)
-						memcpy(dst, cda, bv->bv_len);
+						memcpy(dst, cda, bv.bv_len);
 					kmem_cache_free(dasd_page_cache,
 					    (void *)((addr_t)cda & PAGE_MASK));
 				}