aoe: use packets that work with the smallest-MTU local interface

Users with several network interfaces dedicated to AoE generally do not
configure them to support different-sized AoE data payloads on purpose.

For a given AoE target, there will be a set of local network interfaces
that can reach it.  Using only the payload that will fit in the
smallest-sized MTU of all those local interfaces greatly simplifies the
driver, especially in failure scenarios.

Signed-off-by: Ed Cashin <ecashin@coraid.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/drivers/block/aoe/aoe.h b/drivers/block/aoe/aoe.h
index d0087de1780e0558db66332e986cdd191d2428ec..ffded64dcbeb8ab56e2c9a2762fca0f1a326c8c4 100644 (file)
--- a/drivers/block/aoe/aoe.h
+++ b/drivers/block/aoe/aoe.h
@@ -125,9 +125,8 @@ struct frame {
 
 struct aoeif {
        struct net_device *nd;
-       unsigned char lost;
-       unsigned char lostjumbo;
-       ushort maxbcnt;
+       ulong lost;
+       int bcnt;
 };
 
 struct aoetgt {
@@ -144,6 +143,7 @@ struct aoetgt {
        u16 useme;
        ulong falloc;
        ulong lastwadj;         /* last window adjustment */
+       int minbcnt;
        int wpkts, rpkts;
 };
 
@@ -172,6 +172,7 @@ struct aoedev {
                struct bio *nxbio;
                struct request *rq;
        } ip;
+       ulong maxbcnt;
        struct aoetgt *targets[NTARGETS];
        struct aoetgt **tgt;    /* target in use when working */
        struct aoetgt *htgt;    /* target needing rexmit assistance */

diff --git a/drivers/block/aoe/aoecmd.c b/drivers/block/aoe/aoecmd.c
index 5cc4d3a2b7cb29c8399e3759380934ac815f4a03..cf196eddc8e23fb304e8f9233c113ee1828852dd 100644 (file)
--- a/drivers/block/aoe/aoecmd.c
+++ b/drivers/block/aoe/aoecmd.c
@@ -118,16 +118,18 @@ put_lba(struct aoe_atahdr *ah, sector_t lba)
        ah->lba5 = lba >>= 8;
 }
 
-static void
+static struct aoeif *
 ifrotate(struct aoetgt *t)
 {
-       t->ifp++;
-       if (t->ifp >= &t->ifs[NAOEIFS] || t->ifp->nd == NULL)
-               t->ifp = t->ifs;
-       if (t->ifp->nd == NULL) {
-               printk(KERN_INFO "aoe: no interface to rotate to\n");
-               BUG();
-       }
+       struct aoeif *ifp;
+
+       ifp = t->ifp;
+       ifp++;
+       if (ifp >= &t->ifs[NAOEIFS] || ifp->nd == NULL)
+               ifp = t->ifs;
+       if (ifp->nd == NULL)
+               return NULL;
+       return t->ifp = ifp;
 }
 
 static void
@@ -231,8 +233,8 @@ newframe(struct aoedev *d)
                && t->ifp->nd) {
                        f = newtframe(d, t);
                        if (f) {
-                               d->tgt = tt;
                                ifrotate(t);
+                               d->tgt = tt;
                                return f;
                        }
                }
@@ -299,7 +301,7 @@ aoecmd_ata_rw(struct aoedev *d)
                return 0;
        t = *d->tgt;
        bv = buf->bv;
-       bcnt = t->ifp->maxbcnt;
+       bcnt = d->maxbcnt;
        if (bcnt == 0)
                bcnt = DEFAULTBCNT;
        if (bcnt > buf->resid)
@@ -430,9 +432,14 @@ resend(struct aoedev *d, struct frame *f)
        u32 n;
 
        t = f->t;
-       ifrotate(t);
        n = newtag(t);
        skb = f->skb;
+       if (ifrotate(t) == NULL) {
+               /* probably can't happen, but set it up to fail anyway */
+               pr_info("aoe: resend: no interfaces to rotate to.\n");
+               ktcomplete(f, NULL);
+               return;
+       }
        h = (struct aoe_hdr *) skb_mac_header(skb);
        ah = (struct aoe_atahdr *) (h+1);
 
@@ -482,21 +489,6 @@ getif(struct aoetgt *t, struct net_device *nd)
        return NULL;
 }
 
-static struct aoeif *
-addif(struct aoetgt *t, struct net_device *nd)
-{
-       struct aoeif *p;
-
-       p = getif(t, NULL);
-       if (!p)
-               return NULL;
-       p->nd = nd;
-       p->maxbcnt = DEFAULTBCNT;
-       p->lost = 0;
-       p->lostjumbo = 0;
-       return p;
-}
-
 static void
 ejectif(struct aoetgt *t, struct aoeif *ifp)
 {
@@ -545,7 +537,11 @@ sthtith(struct aoedev *d)
                        resend(d, nf);
                }
        }
-       /* he's clean, he's useless.  take away his interfaces */
+       /* We've cleaned up the outstanding so take away his
+        * interfaces so he won't be used.  We should remove him from
+        * the target array here, but cleaning up a target is
+        * involved.  PUNT!
+        */
        memset(ht->ifs, 0, sizeof ht->ifs);
        d->htgt = NULL;
        return 1;
@@ -1014,11 +1010,8 @@ noskb:   if (buf)
        case ATA_CMD_PIO_WRITE_EXT:
                spin_lock_irq(&d->lock);
                ifp = getif(t, skb->dev);
-               if (ifp) {
+               if (ifp)
                        ifp->lost = 0;
-                       if (n > DEFAULTBCNT)
-                               ifp->lostjumbo = 0;
-               }
                if (d->htgt == t) /* I'll help myself, thank you. */
                        d->htgt = NULL;
                spin_unlock_irq(&d->lock);
@@ -1292,6 +1285,56 @@ addtgt(struct aoedev *d, char *addr, ulong nframes)
        return *tt = t;
 }
 
+static void
+setdbcnt(struct aoedev *d)
+{
+       struct aoetgt **t, **e;
+       int bcnt = 0;
+
+       t = d->targets;
+       e = t + NTARGETS;
+       for (; t < e && *t; t++)
+               if (bcnt == 0 || bcnt > (*t)->minbcnt)
+                       bcnt = (*t)->minbcnt;
+       if (bcnt != d->maxbcnt) {
+               d->maxbcnt = bcnt;
+               pr_info("aoe: e%ld.%d: setting %d byte data frames\n",
+                       d->aoemajor, d->aoeminor, bcnt);
+       }
+}
+
+static void
+setifbcnt(struct aoetgt *t, struct net_device *nd, int bcnt)
+{
+       struct aoedev *d;
+       struct aoeif *p, *e;
+       int minbcnt;
+
+       d = t->d;
+       minbcnt = bcnt;
+       p = t->ifs;
+       e = p + NAOEIFS;
+       for (; p < e; p++) {
+               if (p->nd == NULL)
+                       break;          /* end of the valid interfaces */
+               if (p->nd == nd) {
+                       p->bcnt = bcnt; /* we're updating */
+                       nd = NULL;
+               } else if (minbcnt > p->bcnt)
+                       minbcnt = p->bcnt; /* find the min interface */
+       }
+       if (nd) {
+               if (p == e) {
+                       pr_err("aoe: device setifbcnt failure; too many interfaces.\n");
+                       return;
+               }
+               p->nd = nd;
+               p->bcnt = bcnt;
+       }
+       t->minbcnt = minbcnt;
+       setdbcnt(d);
+}
+
 void
 aoecmd_cfg_rsp(struct sk_buff *skb)
 {
@@ -1299,7 +1342,6 @@ aoecmd_cfg_rsp(struct sk_buff *skb)
        struct aoe_hdr *h;
        struct aoe_cfghdr *ch;
        struct aoetgt *t;
-       struct aoeif *ifp;
        ulong flags, sysminor, aoemajor;
        struct sk_buff *sl;
        struct sk_buff_head queue;
@@ -1345,32 +1387,13 @@ aoecmd_cfg_rsp(struct sk_buff *skb)
                if (!t)
                        goto bail;
        }
-       ifp = getif(t, skb->dev);
-       if (!ifp) {
-               ifp = addif(t, skb->dev);
-               if (!ifp) {
-                       printk(KERN_INFO
-                               "aoe: device addif failure; "
-                               "too many interfaces?\n");
-                       goto bail;
-               }
-       }
-       if (ifp->maxbcnt) {
-               n = ifp->nd->mtu;
-               n -= sizeof (struct aoe_hdr) + sizeof (struct aoe_atahdr);
-               n /= 512;
-               if (n > ch->scnt)
-                       n = ch->scnt;
-               n = n ? n * 512 : DEFAULTBCNT;
-               if (n != ifp->maxbcnt) {
-                       printk(KERN_INFO
-                               "aoe: e%ld.%d: setting %d%s%s:%pm\n",
-                               d->aoemajor, d->aoeminor, n,
-                               " byte data frames on ", ifp->nd->name,
-                               t->addr);
-                       ifp->maxbcnt = n;
-               }
-       }
+       n = skb->dev->mtu;
+       n -= sizeof(struct aoe_hdr) + sizeof(struct aoe_atahdr);
+       n /= 512;
+       if (n > ch->scnt)
+               n = ch->scnt;
+       n = n ? n * 512 : DEFAULTBCNT;
+       setifbcnt(t, skb->dev, n);
 
        /* don't change users' perspective */
        if (d->nopen == 0) {
@@ -1391,22 +1414,14 @@ void
 aoecmd_cleanslate(struct aoedev *d)
 {
        struct aoetgt **t, **te;
-       struct aoeif *p, *e;
 
        d->mintimer = MINTIMER;
+       d->maxbcnt = 0;
 
        t = d->targets;
        te = t + NTARGETS;
-       for (; t < te && *t; t++) {
+       for (; t < te && *t; t++)
                (*t)->maxout = (*t)->nframes;
-               p = (*t)->ifs;
-               e = p + NAOEIFS;
-               for (; p < e; p++) {
-                       p->lostjumbo = 0;
-                       p->lost = 0;
-                       p->maxbcnt = DEFAULTBCNT;
-               }
-       }
 }
 
 void