aoe: handle multiple network paths to AoE device

A remote AoE device is something can process ATA commands and is identified by
an AoE shelf number and an AoE slot number.  Such a device might have more
than one network interface, and it might be reachable by more than one local
network interface.  This patch tracks the available network paths available to
each AoE device, allowing them to be used more efficiently.

Andrew Morton asked about the call to msleep_interruptible in the revalidate
function.  Yes, if a signal is pending, then msleep_interruptible will not
return 0.  That means we will not loop but will call aoenet_xmit with a NULL
skb, which is a noop.  If the system is too low on memory or the aoe driver is
too low on frames, then the user can hit control-C to interrupt the attempt to
do a revalidate.  I have added a comment to the code summarizing that.

Andrew Morton asked whether the allocation performed inside addtgt could use a
more relaxed allocation like GFP_KERNEL, but addtgt is called when the aoedev
lock has been locked with spin_lock_irqsave.  It would be nice to allocate the
memory under fewer restrictions, but targets are only added when the device is
being discovered, and if the target can't be added right now, we can try again
in a minute when then next AoE config query broadcast goes out.

Andrew Morton pointed out that the "too many targets" message could be printed
for failing GFP_ATOMIC allocations.  The last patch in this series makes the
messages more specific.

Signed-off-by: Ed L. Cashin <ecashin@coraid.com>
Cc: Greg KH <greg@kroah.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 79 insertions, 89 deletions

diff --git a/drivers/block/aoe/aoedev.c b/drivers/block/aoe/aoedev.c
index 51f50710e5fc..a4d625aefeaa 100644
--- a/drivers/block/aoe/aoedev.c
+++ b/drivers/block/aoe/aoedev.c
@@ -15,15 +15,18 @@ static spinlock_t devlist_lock;
 int
 aoedev_isbusy(struct aoedev *d)
 {
+        struct aoetgt **t, **te;
         struct frame *f, *e;
 
-        f = d->frames;
-        e = f + d->nframes;
-        do {
-                if (f->tag != FREETAG)
-                        return 1;
-        } while (++f < e);
-
+        t = d->targets;
+        te = t + NTARGETS;
+        for (; t < te && *t; t++) {
+                f = (*t)->frames;
+                e = f + (*t)->nframes;
+                for (; f < e; f++)
+                        if (f->tag != FREETAG)
+                                return 1;
+        }
         return 0;
 }
 
@@ -55,75 +58,41 @@ dummy_timer(ulong vp)
         add_timer(&d->timer);
 }
 
-/* called with devlist lock held */
-static struct aoedev *
-aoedev_newdev(ulong nframes)
-{
-        struct aoedev *d;
-        struct frame *f, *e;
-
-        d = kzalloc(sizeof *d, GFP_ATOMIC);
-        f = kcalloc(nframes, sizeof *f, GFP_ATOMIC);
-        switch (!d || !f) {
-        case 0:
-                d->nframes = nframes;
-                d->frames = f;
-                e = f + nframes;
-                for (; f<e; f++) {
-                        f->tag = FREETAG;
-                        f->skb = new_skb(ETH_ZLEN);
-                        if (!f->skb)
-                                break;
-                }
-                if (f == e)
-                        break;
-                while (f > d->frames) {
-                        f--;
-                        dev_kfree_skb(f->skb);
-                }
-        default:
-                if (f)
-                        kfree(f);
-                if (d)
-                        kfree(d);
-                return NULL;
-        }
-        INIT_WORK(&d->work, aoecmd_sleepwork);
-        spin_lock_init(&d->lock);
-        init_timer(&d->timer);
-        d->timer.data = (ulong) d;
-        d->timer.function = dummy_timer;
-        d->timer.expires = jiffies + HZ;
-        add_timer(&d->timer);
-        d->bufpool = NULL;      /* defer to aoeblk_gdalloc */
-        INIT_LIST_HEAD(&d->bufq);
-        d->next = devlist;
-        devlist = d;
-
-        return d;
-}
-
 void
 aoedev_downdev(struct aoedev *d)
 {
+        struct aoetgt **t, **te;
         struct frame *f, *e;
         struct buf *buf;
         struct bio *bio;
 
-        f = d->frames;
-        e = f + d->nframes;
-        for (; f<e; f->tag = FREETAG, f->buf = NULL, f++) {
-                if (f->tag == FREETAG || f->buf == NULL)
-                        continue;
-                buf = f->buf;
-                bio = buf->bio;
-                if (--buf->nframesout == 0) {
-                        mempool_free(buf, d->bufpool);
-                        bio_endio(bio, -EIO);
+        t = d->targets;
+        te = t + NTARGETS;
+        for (; t < te && *t; t++) {
+                f = (*t)->frames;
+                e = f + (*t)->nframes;
+                for (; f < e; f->tag = FREETAG, f->buf = NULL, f++) {
+                        if (f->tag == FREETAG || f->buf == NULL)
+                                continue;
+                        buf = f->buf;
+                        bio = buf->bio;
+                        if (--buf->nframesout == 0
+                        && buf != d->inprocess) {
+                                mempool_free(buf, d->bufpool);
+                                bio_endio(bio, -EIO);
+                        }
                 }
-                skb_shinfo(f->skb)->nr_frags = f->skb->data_len = 0;
+                (*t)->maxout = (*t)->nframes;
+                (*t)->nout = 0;
+        }
+        buf = d->inprocess;
+        if (buf) {
+                bio = buf->bio;
+                mempool_free(buf, d->bufpool);
+                bio_endio(bio, -EIO);
         }
         d->inprocess = NULL;
+        d->htgt = NULL;
 
         while (!list_empty(&d->bufq)) {
                 buf = container_of(d->bufq.next, struct buf, bufs);
@@ -136,12 +105,12 @@ aoedev_downdev(struct aoedev *d)
         if (d->gd)
                 d->gd->capacity = 0;
 
-        d->flags &= ~(DEVFL_UP | DEVFL_PAUSE);
+        d->flags &= ~DEVFL_UP;
 }
 
 /* find it or malloc it */
 struct aoedev *
-aoedev_by_sysminor_m(ulong sysminor, ulong bufcnt)
+aoedev_by_sysminor_m(ulong sysminor)
 {
         struct aoedev *d;
         ulong flags;
@@ -151,40 +120,61 @@ aoedev_by_sysminor_m(ulong sysminor, ulong bufcnt)
         for (d=devlist; d; d=d->next)
                 if (d->sysminor == sysminor)
                         break;
-
-        if (d == NULL) {
-                d = aoedev_newdev(bufcnt);
-                if (d == NULL) {
-                        spin_unlock_irqrestore(&devlist_lock, flags);
-                        printk(KERN_INFO "aoe: aoedev_newdev failure.\n");
-                        return NULL;
-                }
-                d->sysminor = sysminor;
-                d->aoemajor = AOEMAJOR(sysminor);
-                d->aoeminor = AOEMINOR(sysminor);
-        }
-
+        if (d)
+                goto out;
+        d = kcalloc(1, sizeof *d, GFP_ATOMIC);
+        if (!d)
+                goto out;
+        INIT_WORK(&d->work, aoecmd_sleepwork);
+        spin_lock_init(&d->lock);
+        init_timer(&d->timer);
+        d->timer.data = (ulong) d;
+        d->timer.function = dummy_timer;
+        d->timer.expires = jiffies + HZ;
+        add_timer(&d->timer);
+        d->bufpool = NULL;      /* defer to aoeblk_gdalloc */
+        d->tgt = d->targets;
+        INIT_LIST_HEAD(&d->bufq);
+        d->sysminor = sysminor;
+        d->aoemajor = AOEMAJOR(sysminor);
+        d->aoeminor = AOEMINOR(sysminor);
+        d->mintimer = MINTIMER;
+        d->next = devlist;
+        devlist = d;
+ out:
         spin_unlock_irqrestore(&devlist_lock, flags);
         return d;
 }
 
 static void
-aoedev_freedev(struct aoedev *d)
+freetgt(struct aoetgt *t)
 {
         struct frame *f, *e;
 
+        f = t->frames;
+        e = f + t->nframes;
+        for (; f < e; f++) {
+                skb_shinfo(f->skb)->nr_frags = 0;
+                dev_kfree_skb(f->skb);
+        }
+        kfree(t->frames);
+        kfree(t);
+}
+
+static void
+aoedev_freedev(struct aoedev *d)
+{
+        struct aoetgt **t, **e;
+
         if (d->gd) {
                 aoedisk_rm_sysfs(d);
                 del_gendisk(d->gd);
                 put_disk(d->gd);
         }
-        f = d->frames;
-        e = f + d->nframes;
-        for (; f<e; f++) {
-                skb_shinfo(f->skb)->nr_frags = 0;
-                dev_kfree_skb(f->skb);
-        }
-        kfree(d->frames);
+        t = d->targets;
+        e = t + NTARGETS;
+        for (; t < e && *t; t++)
+                freetgt(*t);
         if (d->bufpool)
                 mempool_destroy(d->bufpool);
         kfree(d);