block: Abstract out bvec iterator

Immutable biovecs are going to require an explicit iterator. To
implement immutable bvecs, a later patch is going to add a bi_bvec_done
member to this struct; for now, this patch effectively just renames
things.

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: Matthew Wilcox <willy@linux.intel.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: Rusty Russell <rusty@rustcorp.com.au>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: Neil Brown <neilb@suse.de>
Cc: Alasdair Kergon <agk@redhat.com>
Cc: Mike Snitzer <snitzer@redhat.com>
Cc: dm-devel@redhat.com
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: linux390@de.ibm.com
Cc: Boaz Harrosh <bharrosh@panasas.com>
Cc: Benny Halevy <bhalevy@tonian.com>
Cc: "James E.J. Bottomley" <JBottomley@parallels.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "Nicholas A. Bellinger" <nab@linux-iscsi.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Chris Mason <chris.mason@fusionio.com>
Cc: "Theodore Ts'o" <tytso@mit.edu>
Cc: Andreas Dilger <adilger.kernel@dilger.ca>
Cc: Jaegeuk Kim <jaegeuk.kim@samsung.com>
Cc: Steven Whitehouse <swhiteho@redhat.com>
Cc: Dave Kleikamp <shaggy@kernel.org>
Cc: Joern Engel <joern@logfs.org>
Cc: Prasad Joshi <prasadjoshi.linux@gmail.com>
Cc: Trond Myklebust <Trond.Myklebust@netapp.com>
Cc: KONISHI Ryusuke <konishi.ryusuke@lab.ntt.co.jp>
Cc: Mark Fasheh <mfasheh@suse.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Ben Myers <bpm@sgi.com>
Cc: xfs@oss.sgi.com
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Len Brown <len.brown@intel.com>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
Cc: Herton Ronaldo Krzesinski <herton.krzesinski@canonical.com>
Cc: Ben Hutchings <ben@decadent.org.uk>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Guo Chao <yan@linux.vnet.ibm.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Asai Thambi S P <asamymuthupa@micron.com>
Cc: Selvan Mani <smani@micron.com>
Cc: Sam Bradshaw <sbradshaw@micron.com>
Cc: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
Cc: "Roger Pau Monné" <roger.pau@citrix.com>
Cc: Jan Beulich <jbeulich@suse.com>
Cc: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Cc: Ian Campbell <Ian.Campbell@citrix.com>
Cc: Sebastian Ott <sebott@linux.vnet.ibm.com>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Jiang Liu <jiang.liu@huawei.com>
Cc: Nitin Gupta <ngupta@vflare.org>
Cc: Jerome Marchand <jmarchand@redhat.com>
Cc: Joe Perches <joe@perches.com>
Cc: Peng Tao <tao.peng@emc.com>
Cc: Andy Adamson <andros@netapp.com>
Cc: fanchaoting <fanchaoting@cn.fujitsu.com>
Cc: Jie Liu <jeff.liu@oracle.com>
Cc: Sunil Mushran <sunil.mushran@gmail.com>
Cc: "Martin K. Petersen" <martin.petersen@oracle.com>
Cc: Namjae Jeon <namjae.jeon@samsung.com>
Cc: Pankaj Kumar <pankaj.km@samsung.com>
Cc: Dan Magenheimer <dan.magenheimer@oracle.com>
Cc: Mel Gorman <mgorman@suse.de>6
diff --git a/fs/btrfs/raid56.c b/fs/btrfs/raid56.c
index 24ac218..9af0b25 100644
--- a/fs/btrfs/raid56.c
+++ b/fs/btrfs/raid56.c
@@ -1032,8 +1032,8 @@
 
 	/* see if we can add this page onto our existing bio */
 	if (last) {
-		last_end = (u64)last->bi_sector << 9;
-		last_end += last->bi_size;
+		last_end = (u64)last->bi_iter.bi_sector << 9;
+		last_end += last->bi_iter.bi_size;
 
 		/*
 		 * we can't merge these if they are from different
@@ -1053,9 +1053,9 @@
 	if (!bio)
 		return -ENOMEM;
 
-	bio->bi_size = 0;
+	bio->bi_iter.bi_size = 0;
 	bio->bi_bdev = stripe->dev->bdev;
-	bio->bi_sector = disk_start >> 9;
+	bio->bi_iter.bi_sector = disk_start >> 9;
 	set_bit(BIO_UPTODATE, &bio->bi_flags);
 
 	bio_add_page(bio, page, PAGE_CACHE_SIZE, 0);
@@ -1111,7 +1111,7 @@
 
 	spin_lock_irq(&rbio->bio_list_lock);
 	bio_list_for_each(bio, &rbio->bio_list) {
-		start = (u64)bio->bi_sector << 9;
+		start = (u64)bio->bi_iter.bi_sector << 9;
 		stripe_offset = start - rbio->raid_map[0];
 		page_index = stripe_offset >> PAGE_CACHE_SHIFT;
 
@@ -1272,7 +1272,7 @@
 static int find_bio_stripe(struct btrfs_raid_bio *rbio,
 			   struct bio *bio)
 {
-	u64 physical = bio->bi_sector;
+	u64 physical = bio->bi_iter.bi_sector;
 	u64 stripe_start;
 	int i;
 	struct btrfs_bio_stripe *stripe;
@@ -1298,7 +1298,7 @@
 static int find_logical_bio_stripe(struct btrfs_raid_bio *rbio,
 				   struct bio *bio)
 {
-	u64 logical = bio->bi_sector;
+	u64 logical = bio->bi_iter.bi_sector;
 	u64 stripe_start;
 	int i;
 
@@ -1602,8 +1602,8 @@
 						 plug_list);
 	struct btrfs_raid_bio *rb = container_of(b, struct btrfs_raid_bio,
 						 plug_list);
-	u64 a_sector = ra->bio_list.head->bi_sector;
-	u64 b_sector = rb->bio_list.head->bi_sector;
+	u64 a_sector = ra->bio_list.head->bi_iter.bi_sector;
+	u64 b_sector = rb->bio_list.head->bi_iter.bi_sector;
 
 	if (a_sector < b_sector)
 		return -1;
@@ -1691,7 +1691,7 @@
 	if (IS_ERR(rbio))
 		return PTR_ERR(rbio);
 	bio_list_add(&rbio->bio_list, bio);
-	rbio->bio_list_bytes = bio->bi_size;
+	rbio->bio_list_bytes = bio->bi_iter.bi_size;
 
 	/*
 	 * don't plug on full rbios, just get them out the door
@@ -2044,7 +2044,7 @@
 
 	rbio->read_rebuild = 1;
 	bio_list_add(&rbio->bio_list, bio);
-	rbio->bio_list_bytes = bio->bi_size;
+	rbio->bio_list_bytes = bio->bi_iter.bi_size;
 
 	rbio->faila = find_logical_bio_stripe(rbio, bio);
 	if (rbio->faila == -1) {