block: Abstract out bvec iterator

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 <[email protected]>
Cc: Jens Axboe <[email protected]>
Cc: Geert Uytterhoeven <[email protected]>
Cc: Benjamin Herrenschmidt <[email protected]>
Cc: Paul Mackerras <[email protected]>
Cc: "Ed L. Cashin" <[email protected]>
Cc: Nick Piggin <[email protected]>
Cc: Lars Ellenberg <[email protected]>
Cc: Jiri Kosina <[email protected]>
Cc: Matthew Wilcox <[email protected]>
Cc: Geoff Levand <[email protected]>
Cc: Yehuda Sadeh <[email protected]>
Cc: Sage Weil <[email protected]>
Cc: Alex Elder <[email protected]>
Cc: [email protected]
Cc: Joshua Morris <[email protected]>
Cc: Philip Kelleher <[email protected]>
Cc: Rusty Russell <[email protected]>
Cc: "Michael S. Tsirkin" <[email protected]>
Cc: Konrad Rzeszutek Wilk <[email protected]>
Cc: Jeremy Fitzhardinge <[email protected]>
Cc: Neil Brown <[email protected]>
Cc: Alasdair Kergon <[email protected]>
Cc: Mike Snitzer <[email protected]>
Cc: [email protected]
Cc: Martin Schwidefsky <[email protected]>
Cc: Heiko Carstens <[email protected]>
Cc: [email protected]
Cc: Boaz Harrosh <[email protected]>
Cc: Benny Halevy <[email protected]>
Cc: "James E.J. Bottomley" <[email protected]>
Cc: Greg Kroah-Hartman <[email protected]>
Cc: "Nicholas A. Bellinger" <[email protected]>
Cc: Alexander Viro <[email protected]>
Cc: Chris Mason <[email protected]>
Cc: "Theodore Ts'o" <[email protected]>
Cc: Andreas Dilger <[email protected]>
Cc: Jaegeuk Kim <[email protected]>
Cc: Steven Whitehouse <[email protected]>
Cc: Dave Kleikamp <[email protected]>
Cc: Joern Engel <[email protected]>
Cc: Prasad Joshi <[email protected]>
Cc: Trond Myklebust <[email protected]>
Cc: KONISHI Ryusuke <[email protected]>
Cc: Mark Fasheh <[email protected]>
Cc: Joel Becker <[email protected]>
Cc: Ben Myers <[email protected]>
Cc: [email protected]
Cc: Steven Rostedt <[email protected]>
Cc: Frederic Weisbecker <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Len Brown <[email protected]>
Cc: Pavel Machek <[email protected]>
Cc: "Rafael J. Wysocki" <[email protected]>
Cc: Herton Ronaldo Krzesinski <[email protected]>
Cc: Ben Hutchings <[email protected]>
Cc: Andrew Morton <[email protected]>
Cc: Guo Chao <[email protected]>
Cc: Tejun Heo <[email protected]>
Cc: Asai Thambi S P <[email protected]>
Cc: Selvan Mani <[email protected]>
Cc: Sam Bradshaw <[email protected]>
Cc: Wei Yongjun <[email protected]>
Cc: "Roger Pau Monné" <[email protected]>
Cc: Jan Beulich <[email protected]>
Cc: Stefano Stabellini <[email protected]>
Cc: Ian Campbell <[email protected]>
Cc: Sebastian Ott <[email protected]>
Cc: Christian Borntraeger <[email protected]>
Cc: Minchan Kim <[email protected]>
Cc: Jiang Liu <[email protected]>
Cc: Nitin Gupta <[email protected]>
Cc: Jerome Marchand <[email protected]>
Cc: Joe Perches <[email protected]>
Cc: Peng Tao <[email protected]>
Cc: Andy Adamson <[email protected]>
Cc: fanchaoting <[email protected]>
Cc: Jie Liu <[email protected]>
Cc: Sunil Mushran <[email protected]>
Cc: "Martin K. Petersen" <[email protected]>
Cc: Namjae Jeon <[email protected]>
Cc: Pankaj Kumar <[email protected]>
Cc: Dan Magenheimer <[email protected]>
Cc: Mel Gorman <[email protected]>6