aoe: zero copy write 2 of 2

Avoid memory copy on writes.
(This patch follows patch 4.)

Signed-off-by: "Ed L. Cashin" <ecashin@coraid.com>
Acked-by: Alan Cox <alan@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 62 insertions, 20 deletions

diff --git a/drivers/block/aoe/aoecmd.c b/drivers/block/aoe/aoecmd.c
index c0bdc1fe21f0..9ebc98ade3c5 100644
--- a/drivers/block/aoe/aoecmd.c
+++ b/drivers/block/aoe/aoecmd.c
@@ -120,7 +120,7 @@ aoecmd_ata_rw(struct aoedev *d, struct frame *f)
         h = (struct aoe_hdr *) skb->mac.raw;
         ah = (struct aoe_atahdr *) (h+1);
         skb->len = sizeof *h + sizeof *ah;
-        memset(h, 0, skb->len);
+        memset(h, 0, ETH_ZLEN);
         f->tag = aoehdr_atainit(d, h);
         f->waited = 0;
         f->buf = buf;
@@ -143,8 +143,9 @@ aoecmd_ata_rw(struct aoedev *d, struct frame *f)
                 skb_fill_page_desc(skb, 0, virt_to_page(f->bufaddr),
                         offset_in_page(f->bufaddr), bcnt);
                 ah->aflags |= AOEAFL_WRITE;
+                skb->len += bcnt;
+                skb->data_len = bcnt;
         } else {
-                skb_shinfo(skb)->nr_frags = 0;
                 skb->len = ETH_ZLEN;
                 writebit = 0;
         }
@@ -167,8 +168,9 @@ aoecmd_ata_rw(struct aoedev *d, struct frame *f)
         }
 
         skb->dev = d->ifp;
-        skb_get(skb);
-        skb->next = NULL;
+        skb = skb_clone(skb, GFP_ATOMIC);
+        if (skb == NULL)
+                return;
         if (d->sendq_hd)
                 d->sendq_tl->next = skb;
         else
@@ -224,6 +226,29 @@ aoecmd_cfg_pkts(ushort aoemajor, unsigned char aoeminor, struct sk_buff **tail)
         return sl;
 }
 
+static struct frame *
+freeframe(struct aoedev *d)
+{
+        struct frame *f, *e;
+        int n = 0;
+
+        f = d->frames;
+        e = f + d->nframes;
+        for (; f<e; f++) {
+                if (f->tag != FREETAG)
+                        continue;
+                if (atomic_read(&skb_shinfo(f->skb)->dataref) == 1) {
+                        skb_shinfo(f->skb)->nr_frags = f->skb->data_len = 0;
+                        return f;
+                }
+                n++;
+        }
+        if (n == d->nframes)    /* wait for network layer */
+                d->flags |= DEVFL_KICKME;
+
+        return NULL;
+}
+
 /* enters with d->lock held */
 void
 aoecmd_work(struct aoedev *d)
@@ -239,7 +264,7 @@ aoecmd_work(struct aoedev *d)
         }
 
 loop:
-        f = getframe(d, FREETAG);
+        f = freeframe(d);
         if (f == NULL)
                 return;
         if (d->inprocess == NULL) {
@@ -282,20 +307,25 @@ rexmit(struct aoedev *d, struct frame *f)
         n = DEFAULTBCNT / 512;
         if (ah->scnt > n) {
                 ah->scnt = n;
-                if (ah->aflags & AOEAFL_WRITE)
+                if (ah->aflags & AOEAFL_WRITE) {
                         skb_fill_page_desc(skb, 0, virt_to_page(f->bufaddr),
                                 offset_in_page(f->bufaddr), DEFAULTBCNT);
+                        skb->len = sizeof *h + sizeof *ah + DEFAULTBCNT;
+                        skb->data_len = DEFAULTBCNT;
+                }
                 if (++d->lostjumbo > (d->nframes << 1))
                 if (d->maxbcnt != DEFAULTBCNT) {
-                        iprintk("too many lost jumbo - using 1KB frames.\n");
+                        iprintk("e%ld.%ld: too many lost jumbo on %s - using 1KB frames.\n",
+                                d->aoemajor, d->aoeminor, d->ifp->name);
                         d->maxbcnt = DEFAULTBCNT;
                         d->flags |= DEVFL_MAXBCNT;
                 }
         }
 
         skb->dev = d->ifp;
-        skb_get(skb);
-        skb->next = NULL;
+        skb = skb_clone(skb, GFP_ATOMIC);
+        if (skb == NULL)
+                return;
         if (d->sendq_hd)
                 d->sendq_tl->next = skb;
         else
@@ -350,6 +380,10 @@ rexmit_timer(ulong vp)
                         rexmit(d, f);
                 }
         }
+        if (d->flags & DEVFL_KICKME) {
+                d->flags &= ~DEVFL_KICKME;
+                aoecmd_work(d);
+        }
 
         sl = d->sendq_hd;
         d->sendq_hd = d->sendq_tl = NULL;
@@ -552,23 +586,27 @@ aoecmd_ata_rsp(struct sk_buff *skb)
                 case WIN_WRITE:
                 case WIN_WRITE_EXT:
                         if (f->bcnt -= n) {
+                                skb = f->skb;
                                 f->bufaddr += n;
                                 put_lba(ahout, f->lba += ahout->scnt);
                                 n = f->bcnt;
                                 if (n > DEFAULTBCNT)
                                         n = DEFAULTBCNT;
                                 ahout->scnt = n >> 9;
-                                if (ahout->aflags & AOEAFL_WRITE)
-                                        skb_fill_page_desc(f->skb, 0,
+                                if (ahout->aflags & AOEAFL_WRITE) {
+                                        skb_fill_page_desc(skb, 0,
                                                 virt_to_page(f->bufaddr),
                                                 offset_in_page(f->bufaddr), n);
+                                        skb->len = sizeof *hout + sizeof *ahout + n;
+                                        skb->data_len = n;
+                                }
                                 f->tag = newtag(d);
                                 hout->tag = cpu_to_be32(f->tag);
                                 skb->dev = d->ifp;
-                                skb_get(f->skb);
-                                f->skb->next = NULL;
+                                skb = skb_clone(skb, GFP_ATOMIC);
                                 spin_unlock_irqrestore(&d->lock, flags);
-                                aoenet_xmit(f->skb);
+                                if (skb)
+                                        aoenet_xmit(skb);
                                 return;
                         }
                         if (n > DEFAULTBCNT)
@@ -642,7 +680,7 @@ aoecmd_ata_id(struct aoedev *d)
         struct frame *f;
         struct sk_buff *skb;
 
-        f = getframe(d, FREETAG);
+        f = freeframe(d);
         if (f == NULL) {
                 eprintk("can't get a frame. This shouldn't happen.\n");
                 return NULL;
@@ -652,8 +690,8 @@ aoecmd_ata_id(struct aoedev *d)
         skb = f->skb;
         h = (struct aoe_hdr *) skb->mac.raw;
         ah = (struct aoe_atahdr *) (h+1);
-        skb->len = sizeof *h + sizeof *ah;
-        memset(h, 0, skb->len);
+        skb->len = ETH_ZLEN;
+        memset(h, 0, ETH_ZLEN);
         f->tag = aoehdr_atainit(d, h);
         f->waited = 0;
 
@@ -663,12 +701,11 @@ aoecmd_ata_id(struct aoedev *d)
         ah->lba3 = 0xa0;
 
         skb->dev = d->ifp;
-        skb_get(skb);
 
         d->rttavg = MAXTIMER;
         d->timer.function = rexmit_timer;
 
-        return skb;
+        return skb_clone(skb, GFP_ATOMIC);
 }
  
 void
@@ -724,7 +761,12 @@ aoecmd_cfg_rsp(struct sk_buff *skb)
                 n /= 512;
                 if (n > ch->scnt)
                         n = ch->scnt;
-                d->maxbcnt = n ? n * 512 : DEFAULTBCNT;
+                n = n ? n * 512 : DEFAULTBCNT;
+                if (n != d->maxbcnt) {
+                        iprintk("e%ld.%ld: setting %d byte data frames on %s\n",
+                                d->aoemajor, d->aoeminor, n, d->ifp->name);
+                        d->maxbcnt = n;
+                }
         }
 
         /* don't change users' perspective */