aoe: Convert to immutable biovecs

Now that we've got a mechanism for immutable biovecs -
bi_iter.bi_bvec_done - we need to convert drivers to use primitives that
respect it instead of using the bvec array directly.

The aoe code no longer has to manually iterate over partial bvecs, so
some struct members go away - other struct members are effectively
renamed:

buf->resid	-> buf->iter.bi_size
buf->sector	-> buf->iter.bi_sector

f->bcnt		-> f->iter.bi_size
f->lba		-> f->iter.bi_sector

Signed-off-by: Kent Overstreet <kmo@daterainc.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: "Ed L. Cashin" <ecashin@coraid.com>

2 files changed, 53 insertions, 92 deletions

diff --git a/drivers/block/aoe/aoe.h b/drivers/block/aoe/aoe.h
index 14a9d1912318..9220f8e833d0 100644
--- a/drivers/block/aoe/aoe.h
+++ b/drivers/block/aoe/aoe.h
@@ -100,11 +100,8 @@ enum {
 
 struct buf {
         ulong nframesout;
-        ulong resid;
-        ulong bv_resid;
-        sector_t sector;
         struct bio *bio;
-        struct bio_vec *bv;
+        struct bvec_iter iter;
         struct request *rq;
 };
 
@@ -120,13 +117,10 @@ struct frame {
         ulong waited;
         ulong waited_total;
         struct aoetgt *t;               /* parent target I belong to */
-        sector_t lba;
         struct sk_buff *skb;            /* command skb freed on module exit */
         struct sk_buff *r_skb;          /* response skb for async processing */
         struct buf *buf;
-        struct bio_vec *bv;
-        ulong bcnt;
-        ulong bv_off;
+        struct bvec_iter iter;
         char flags;
 };
 
diff --git a/drivers/block/aoe/aoecmd.c b/drivers/block/aoe/aoecmd.c
index 7a06aec1dedc..8184451b57c0 100644
--- a/drivers/block/aoe/aoecmd.c
+++ b/drivers/block/aoe/aoecmd.c
@@ -196,8 +196,7 @@ aoe_freetframe(struct frame *f)
 
         t = f->t;
         f->buf = NULL;
-        f->lba = 0;
-        f->bv = NULL;
+        memset(&f->iter, 0, sizeof(f->iter));
         f->r_skb = NULL;
         f->flags = 0;
         list_add(&f->head, &t->ffree);
@@ -295,21 +294,14 @@ newframe(struct aoedev *d)
 }
 
 static void
-skb_fillup(struct sk_buff *skb, struct bio_vec *bv, ulong off, ulong cnt)
+skb_fillup(struct sk_buff *skb, struct bio *bio, struct bvec_iter iter)
 {
         int frag = 0;
-        ulong fcnt;
-loop:
-        fcnt = bv->bv_len - (off - bv->bv_offset);
-        if (fcnt > cnt)
-                fcnt = cnt;
-        skb_fill_page_desc(skb, frag++, bv->bv_page, off, fcnt);
-        cnt -= fcnt;
-        if (cnt <= 0)
-                return;
-        bv++;
-        off = bv->bv_offset;
-        goto loop;
+        struct bio_vec bv;
+
+        __bio_for_each_segment(bv, bio, iter, iter)
+                skb_fill_page_desc(skb, frag++, bv.bv_page,
+                                   bv.bv_offset, bv.bv_len);
 }
 
 static void
@@ -346,12 +338,10 @@ ata_rw_frameinit(struct frame *f)
         t->nout++;
         f->waited = 0;
         f->waited_total = 0;
-        if (f->buf)
-                f->lba = f->buf->sector;
 
         /* set up ata header */
-        ah->scnt = f->bcnt >> 9;
-        put_lba(ah, f->lba);
+        ah->scnt = f->iter.bi_size >> 9;
+        put_lba(ah, f->iter.bi_sector);
         if (t->d->flags & DEVFL_EXT) {
                 ah->aflags |= AOEAFL_EXT;
         } else {
@@ -360,11 +350,11 @@ ata_rw_frameinit(struct frame *f)
                 ah->lba3 |= 0xe0;       /* LBA bit + obsolete 0xa0 */
         }
         if (f->buf && bio_data_dir(f->buf->bio) == WRITE) {
-                skb_fillup(skb, f->bv, f->bv_off, f->bcnt);
+                skb_fillup(skb, f->buf->bio, f->iter);
                 ah->aflags |= AOEAFL_WRITE;
-                skb->len += f->bcnt;
-                skb->data_len = f->bcnt;
-                skb->truesize += f->bcnt;
+                skb->len += f->iter.bi_size;
+                skb->data_len = f->iter.bi_size;
+                skb->truesize += f->iter.bi_size;
                 t->wpkts++;
         } else {
                 t->rpkts++;
@@ -382,7 +372,6 @@ aoecmd_ata_rw(struct aoedev *d)
         struct buf *buf;
         struct sk_buff *skb;
         struct sk_buff_head queue;
-        ulong bcnt, fbcnt;
 
         buf = nextbuf(d);
         if (buf == NULL)
@@ -390,39 +379,22 @@ aoecmd_ata_rw(struct aoedev *d)
         f = newframe(d);
         if (f == NULL)
                 return 0;
-        bcnt = d->maxbcnt;
-        if (bcnt == 0)
-                bcnt = DEFAULTBCNT;
-        if (bcnt > buf->resid)
-                bcnt = buf->resid;
-        fbcnt = bcnt;
-        f->bv = buf->bv;
-        f->bv_off = f->bv->bv_offset + (f->bv->bv_len - buf->bv_resid);
-        do {
-                if (fbcnt < buf->bv_resid) {
-                        buf->bv_resid -= fbcnt;
-                        buf->resid -= fbcnt;
-                        break;
-                }
-                fbcnt -= buf->bv_resid;
-                buf->resid -= buf->bv_resid;
-                if (buf->resid == 0) {
-                        d->ip.buf = NULL;
-                        break;
-                }
-                buf->bv++;
-                buf->bv_resid = buf->bv->bv_len;
-                WARN_ON(buf->bv_resid == 0);
-        } while (fbcnt);
 
         /* initialize the headers & frame */
         f->buf = buf;
-        f->bcnt = bcnt;
-        ata_rw_frameinit(f);
+        f->iter = buf->iter;
+        f->iter.bi_size = min_t(unsigned long,
+                                d->maxbcnt ?: DEFAULTBCNT,
+                                f->iter.bi_size);
+        bio_advance_iter(buf->bio, &buf->iter, f->iter.bi_size);
+
+        if (!buf->iter.bi_size)
+                d->ip.buf = NULL;
 
         /* mark all tracking fields and load out */
         buf->nframesout += 1;
-        buf->sector += bcnt >> 9;
+
+        ata_rw_frameinit(f);
 
         skb = skb_clone(f->skb, GFP_ATOMIC);
         if (skb) {
@@ -613,10 +585,7 @@ reassign_frame(struct frame *f)
         skb = nf->skb;
         nf->skb = f->skb;
         nf->buf = f->buf;
-        nf->bcnt = f->bcnt;
-        nf->lba = f->lba;
-        nf->bv = f->bv;
-        nf->bv_off = f->bv_off;
+        nf->iter = f->iter;
         nf->waited = 0;