aoe: use a kernel thread for transmissions

[mirror_ubuntu-bionic-kernel.git] / drivers / block / aoe / aoecmd.c

/* Copyright (c) 2007 Coraid, Inc.  See COPYING for GPL terms. */
/*
 * aoecmd.c
 * Filesystem request handling methods
 */

#include <linux/ata.h>
#include <linux/slab.h>
#include <linux/hdreg.h>
#include <linux/blkdev.h>
#include <linux/skbuff.h>
#include <linux/netdevice.h>
#include <linux/genhd.h>
#include <linux/moduleparam.h>
#include <linux/workqueue.h>
#include <linux/kthread.h>
#include <net/net_namespace.h>
#include <asm/unaligned.h>
#include <linux/uio.h>
#include "aoe.h"

#define MAXIOC (8192)   /* default meant to avoid most soft lockups */

static void ktcomplete(struct frame *, struct sk_buff *);

static struct buf *nextbuf(struct aoedev *);

static int aoe_deadsecs = 60 * 3;
module_param(aoe_deadsecs, int, 0644);
MODULE_PARM_DESC(aoe_deadsecs, "After aoe_deadsecs seconds, give up and fail dev.");

static int aoe_maxout = 16;
module_param(aoe_maxout, int, 0644);
MODULE_PARM_DESC(aoe_maxout,
        "Only aoe_maxout outstanding packets for every MAC on eX.Y.");

static wait_queue_head_t ktiowq;
static struct ktstate kts;

/* io completion queue */
static struct {
        struct list_head head;
        spinlock_t lock;
} iocq;

static struct sk_buff *
new_skb(ulong len)
{
        struct sk_buff *skb;

        skb = alloc_skb(len, GFP_ATOMIC);
        if (skb) {
                skb_reset_mac_header(skb);
                skb_reset_network_header(skb);
                skb->protocol = __constant_htons(ETH_P_AOE);
                skb_checksum_none_assert(skb);
        }
        return skb;
}

static struct frame *
getframe(struct aoetgt *t, u32 tag)
{
        struct frame *f;
        struct list_head *head, *pos, *nx;
        u32 n;

        n = tag % NFACTIVE;
        head = &t->factive[n];
        list_for_each_safe(pos, nx, head) {
                f = list_entry(pos, struct frame, head);
                if (f->tag == tag) {
                        list_del(pos);
                        return f;
                }
        }
        return NULL;
}

/*
 * Leave the top bit clear so we have tagspace for userland.
 * The bottom 16 bits are the xmit tick for rexmit/rttavg processing.
 * This driver reserves tag -1 to mean "unused frame."
 */
static int
newtag(struct aoetgt *t)
{
        register ulong n;

        n = jiffies & 0xffff;
        return n |= (++t->lasttag & 0x7fff) << 16;
}

static u32
aoehdr_atainit(struct aoedev *d, struct aoetgt *t, struct aoe_hdr *h)
{
        u32 host_tag = newtag(t);

        memcpy(h->src, t->ifp->nd->dev_addr, sizeof h->src);
        memcpy(h->dst, t->addr, sizeof h->dst);
        h->type = __constant_cpu_to_be16(ETH_P_AOE);
        h->verfl = AOE_HVER;
        h->major = cpu_to_be16(d->aoemajor);
        h->minor = d->aoeminor;
        h->cmd = AOECMD_ATA;
        h->tag = cpu_to_be32(host_tag);

        return host_tag;
}

static inline void
put_lba(struct aoe_atahdr *ah, sector_t lba)
{
        ah->lba0 = lba;
        ah->lba1 = lba >>= 8;
        ah->lba2 = lba >>= 8;
        ah->lba3 = lba >>= 8;
        ah->lba4 = lba >>= 8;
        ah->lba5 = lba >>= 8;
}

static void
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();
        }
}

static void
skb_pool_put(struct aoedev *d, struct sk_buff *skb)
{
        __skb_queue_tail(&d->skbpool, skb);
}

static struct sk_buff *
skb_pool_get(struct aoedev *d)
{
        struct sk_buff *skb = skb_peek(&d->skbpool);

        if (skb && atomic_read(&skb_shinfo(skb)->dataref) == 1) {
                __skb_unlink(skb, &d->skbpool);
                return skb;
        }
        if (skb_queue_len(&d->skbpool) < NSKBPOOLMAX &&
            (skb = new_skb(ETH_ZLEN)))
                return skb;

        return NULL;
}

void
aoe_freetframe(struct frame *f)
{
        struct aoetgt *t;

        t = f->t;
        f->buf = NULL;
        f->bv = NULL;
        f->r_skb = NULL;
        list_add(&f->head, &t->ffree);
}

static struct frame *
newtframe(struct aoedev *d, struct aoetgt *t)
{
        struct frame *f;
        struct sk_buff *skb;
        struct list_head *pos;

        if (list_empty(&t->ffree)) {
                if (t->falloc >= NSKBPOOLMAX*2)
                        return NULL;
                f = kcalloc(1, sizeof(*f), GFP_ATOMIC);
                if (f == NULL)
                        return NULL;
                t->falloc++;
                f->t = t;
        } else {
                pos = t->ffree.next;
                list_del(pos);
                f = list_entry(pos, struct frame, head);
        }

        skb = f->skb;
        if (skb == NULL) {
                f->skb = skb = new_skb(ETH_ZLEN);
                if (!skb) {
bail:                   aoe_freetframe(f);
                        return NULL;
                }
        }

        if (atomic_read(&skb_shinfo(skb)->dataref) != 1) {
                skb = skb_pool_get(d);
                if (skb == NULL)
                        goto bail;
                skb_pool_put(d, f->skb);
                f->skb = skb;
        }

        skb->truesize -= skb->data_len;
        skb_shinfo(skb)->nr_frags = skb->data_len = 0;
        skb_trim(skb, 0);
        return f;
}

static struct frame *
newframe(struct aoedev *d)
{
        struct frame *f;
        struct aoetgt *t, **tt;
        int totout = 0;

        if (d->targets[0] == NULL) {    /* shouldn't happen, but I'm paranoid */
                printk(KERN_ERR "aoe: NULL TARGETS!\n");
                return NULL;
        }
        tt = d->tgt;    /* last used target */
        for (;;) {
                tt++;
                if (tt >= &d->targets[NTARGETS] || !*tt)
                        tt = d->targets;
                t = *tt;
                totout += t->nout;
                if (t->nout < t->maxout
                && t != d->htgt
                && t->ifp->nd) {
                        f = newtframe(d, t);
                        if (f) {
                                d->tgt = tt;
                                ifrotate(t);
                                return f;
                        }
                }
                if (tt == d->tgt)       /* we've looped and found nada */
                        break;
        }
        if (totout == 0) {
                d->kicked++;
                d->flags |= DEVFL_KICKME;
        }
        return NULL;
}

static void
skb_fillup(struct sk_buff *skb, struct bio_vec *bv, ulong off, ulong cnt)
{
        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;
}

static void
fhash(struct frame *f)
{
        struct aoetgt *t = f->t;
        u32 n;

        n = f->tag % NFACTIVE;
        list_add_tail(&f->head, &t->factive[n]);
}

static int
aoecmd_ata_rw(struct aoedev *d)
{
        struct frame *f;
        struct aoe_hdr *h;
        struct aoe_atahdr *ah;
        struct buf *buf;
        struct bio_vec *bv;
        struct aoetgt *t;
        struct sk_buff *skb;
        struct sk_buff_head queue;
        ulong bcnt, fbcnt;
        char writebit, extbit;

        writebit = 0x10;
        extbit = 0x4;

        buf = nextbuf(d);
        if (buf == NULL)
                return 0;
        f = newframe(d);
        if (f == NULL)
                return 0;
        t = *d->tgt;
        bv = buf->bv;
        bcnt = t->ifp->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 */
        skb = f->skb;
        h = (struct aoe_hdr *) skb_mac_header(skb);
        ah = (struct aoe_atahdr *) (h+1);
        skb_put(skb, sizeof *h + sizeof *ah);
        memset(h, 0, skb->len);
        f->tag = aoehdr_atainit(d, t, h);
        fhash(f);
        t->nout++;
        f->waited = 0;
        f->buf = buf;
        f->bcnt = bcnt;
        f->lba = buf->sector;

        /* set up ata header */
        ah->scnt = bcnt >> 9;
        put_lba(ah, buf->sector);
        if (d->flags & DEVFL_EXT) {
                ah->aflags |= AOEAFL_EXT;
        } else {
                extbit = 0;
                ah->lba3 &= 0x0f;
                ah->lba3 |= 0xe0;       /* LBA bit + obsolete 0xa0 */
        }
        if (bio_data_dir(buf->bio) == WRITE) {
                skb_fillup(skb, f->bv, f->bv_off, bcnt);
                ah->aflags |= AOEAFL_WRITE;
                skb->len += bcnt;
                skb->data_len = bcnt;
                skb->truesize += bcnt;
                t->wpkts++;
        } else {
                t->rpkts++;
                writebit = 0;
        }

        ah->cmdstat = ATA_CMD_PIO_READ | writebit | extbit;

        /* mark all tracking fields and load out */
        buf->nframesout += 1;
        buf->sector += bcnt >> 9;

        skb->dev = t->ifp->nd;
        skb = skb_clone(skb, GFP_ATOMIC);
        if (skb) {
                __skb_queue_head_init(&queue);
                __skb_queue_tail(&queue, skb);
                aoenet_xmit(&queue);
        }
        return 1;
}

/* some callers cannot sleep, and they can call this function,
 * transmitting the packets later, when interrupts are on
 */
static void
aoecmd_cfg_pkts(ushort aoemajor, unsigned char aoeminor, struct sk_buff_head *queue)
{
        struct aoe_hdr *h;
        struct aoe_cfghdr *ch;
        struct sk_buff *skb;
        struct net_device *ifp;

        rcu_read_lock();
        for_each_netdev_rcu(&init_net, ifp) {
                dev_hold(ifp);
                if (!is_aoe_netif(ifp))
                        goto cont;

                skb = new_skb(sizeof *h + sizeof *ch);
                if (skb == NULL) {
                        printk(KERN_INFO "aoe: skb alloc failure\n");
                        goto cont;
                }
                skb_put(skb, sizeof *h + sizeof *ch);
                skb->dev = ifp;
                __skb_queue_tail(queue, skb);
                h = (struct aoe_hdr *) skb_mac_header(skb);
                memset(h, 0, sizeof *h + sizeof *ch);

                memset(h->dst, 0xff, sizeof h->dst);
                memcpy(h->src, ifp->dev_addr, sizeof h->src);
                h->type = __constant_cpu_to_be16(ETH_P_AOE);
                h->verfl = AOE_HVER;
                h->major = cpu_to_be16(aoemajor);
                h->minor = aoeminor;
                h->cmd = AOECMD_CFG;

cont:
                dev_put(ifp);
        }
        rcu_read_unlock();
}

static void
resend(struct aoedev *d, struct frame *f)
{
        struct sk_buff *skb;
        struct sk_buff_head queue;
        struct aoe_hdr *h;
        struct aoe_atahdr *ah;
        struct aoetgt *t;
        char buf[128];
        u32 n;

        t = f->t;
        ifrotate(t);
        n = newtag(t);
        skb = f->skb;
        h = (struct aoe_hdr *) skb_mac_header(skb);
        ah = (struct aoe_atahdr *) (h+1);

        snprintf(buf, sizeof buf,
                "%15s e%ld.%d oldtag=%08x@%08lx newtag=%08x s=%pm d=%pm nout=%d\n",
                "retransmit", d->aoemajor, d->aoeminor, f->tag, jiffies, n,
                h->src, h->dst, t->nout);
        aoechr_error(buf);

        f->tag = n;
        fhash(f);
        h->tag = cpu_to_be32(n);
        memcpy(h->dst, t->addr, sizeof h->dst);
        memcpy(h->src, t->ifp->nd->dev_addr, sizeof h->src);

        skb->dev = t->ifp->nd;
        skb = skb_clone(skb, GFP_ATOMIC);
        if (skb == NULL)
                return;
        __skb_queue_head_init(&queue);
        __skb_queue_tail(&queue, skb);
        aoenet_xmit(&queue);
}

static int
tsince(u32 tag)
{
        int n;

        n = jiffies & 0xffff;
        n -= tag & 0xffff;
        if (n < 0)
                n += 1<<16;
        return n;
}

static struct aoeif *
getif(struct aoetgt *t, struct net_device *nd)
{
        struct aoeif *p, *e;

        p = t->ifs;
        e = p + NAOEIFS;
        for (; p < e; p++)
                if (p->nd == nd)
                        return p;
        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)
{
        struct aoeif *e;
        ulong n;

        e = t->ifs + NAOEIFS - 1;
        n = (e - ifp) * sizeof *ifp;
        memmove(ifp, ifp+1, n);
        e->nd = NULL;
}

static int
sthtith(struct aoedev *d)
{
        struct frame *f, *nf;
        struct list_head *nx, *pos, *head;
        struct sk_buff *skb;
        struct aoetgt *ht = d->htgt;
        int i;

        for (i = 0; i < NFACTIVE; i++) {
                head = &ht->factive[i];
                list_for_each_safe(pos, nx, head) {
                        f = list_entry(pos, struct frame, head);
                        nf = newframe(d);
                        if (!nf)
                                return 0;

                        /* remove frame from active list */
                        list_del(pos);

                        /* reassign all pertinent bits to new outbound frame */
                        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->waited = 0;
                        f->skb = skb;
                        aoe_freetframe(f);
                        ht->nout--;
                        nf->t->nout++;
                        resend(d, nf);
                }
        }
        /* he's clean, he's useless.  take away his interfaces */
        memset(ht->ifs, 0, sizeof ht->ifs);
        d->htgt = NULL;
        return 1;
}

static inline unsigned char
ata_scnt(unsigned char *packet) {
        struct aoe_hdr *h;
        struct aoe_atahdr *ah;

        h = (struct aoe_hdr *) packet;
        ah = (struct aoe_atahdr *) (h+1);
        return ah->scnt;
}

static void
rexmit_timer(ulong vp)
{
        struct aoedev *d;
        struct aoetgt *t, **tt, **te;
        struct aoeif *ifp;
        struct frame *f;
        struct list_head *head, *pos, *nx;
        LIST_HEAD(flist);
        register long timeout;
        ulong flags, n;
        int i;

        d = (struct aoedev *) vp;

        /* timeout is always ~150% of the moving average */
        timeout = d->rttavg;
        timeout += timeout >> 1;

        spin_lock_irqsave(&d->lock, flags);

        if (d->flags & DEVFL_TKILL) {
                spin_unlock_irqrestore(&d->lock, flags);
                return;
        }

        /* collect all frames to rexmit into flist */
        tt = d->targets;
        te = tt + NTARGETS;
        for (; tt < te && *tt; tt++) {
                t = *tt;
                for (i = 0; i < NFACTIVE; i++) {
                        head = &t->factive[i];
                        list_for_each_safe(pos, nx, head) {
                                f = list_entry(pos, struct frame, head);
                                if (tsince(f->tag) < timeout)
                                        continue;
                                /* move to flist for later processing */
                                list_move_tail(pos, &flist);
                        }
                }

                /* window check */
                if (t->nout == t->maxout
                && t->maxout < t->nframes
                && (jiffies - t->lastwadj)/HZ > 10) {
                        t->maxout++;
                        t->lastwadj = jiffies;
                }
        }

        if (!list_empty(&flist)) {      /* retransmissions necessary */
                n = d->rttavg <<= 1;
                if (n > MAXTIMER)
                        d->rttavg = MAXTIMER;
        }

        /* process expired frames */
        while (!list_empty(&flist)) {
                pos = flist.next;
                f = list_entry(pos, struct frame, head);
                n = f->waited += timeout;
                n /= HZ;
                if (n > aoe_deadsecs) {
                        /* Waited too long.  Device failure.
                         * Hang all frames on first hash bucket for downdev
                         * to clean up.
                         */
                        list_splice(&flist, &f->t->factive[0]);
                        aoedev_downdev(d);
                        break;
                }
                list_del(pos);

                t = f->t;
                if (n > HELPWAIT) {
                        /* see if another target can help */
                        if (d->ntargets > 1)
                                d->htgt = t;
                }
                if (t->nout == t->maxout) {
                        if (t->maxout > 1)
                                t->maxout--;
                        t->lastwadj = jiffies;
                }

                ifp = getif(t, f->skb->dev);
                if (ifp && ++ifp->lost > (t->nframes << 1)
                && (ifp != t->ifs || t->ifs[1].nd)) {
                        ejectif(t, ifp);
                        ifp = NULL;
                }
                resend(d, f);
        }

        if ((d->flags & DEVFL_KICKME || d->htgt) && d->blkq) {
                d->flags &= ~DEVFL_KICKME;
                d->blkq->request_fn(d->blkq);
        }

        d->timer.expires = jiffies + TIMERTICK;
        add_timer(&d->timer);

        spin_unlock_irqrestore(&d->lock, flags);
}

static unsigned long
rqbiocnt(struct request *r)
{
        struct bio *bio;
        unsigned long n = 0;

        __rq_for_each_bio(bio, r)
                n++;
        return n;
}

/* This can be removed if we are certain that no users of the block
 * layer will ever use zero-count pages in bios.  Otherwise we have to
 * protect against the put_page sometimes done by the network layer.
 *
 * See http://oss.sgi.com/archives/xfs/2007-01/msg00594.html for
 * discussion.
 *
 * We cannot use get_page in the workaround, because it insists on a
 * positive page count as a precondition.  So we use _count directly.
 */
static void
bio_pageinc(struct bio *bio)
{
        struct bio_vec *bv;
        struct page *page;
        int i;

        bio_for_each_segment(bv, bio, i) {
                page = bv->bv_page;
                /* Non-zero page count for non-head members of
                 * compound pages is no longer allowed by the kernel,
                 * but this has never been seen here.
                 */
                if (unlikely(PageCompound(page)))
                        if (compound_trans_head(page) != page) {
                                pr_crit("page tail used for block I/O\n");
                                BUG();
                        }
                atomic_inc(&page->_count);
        }
}

static void
bio_pagedec(struct bio *bio)
{
        struct bio_vec *bv;
        int i;

        bio_for_each_segment(bv, bio, i)
                atomic_dec(&bv->bv_page->_count);
}

static void
bufinit(struct buf *buf, struct request *rq, struct bio *bio)
{
        struct bio_vec *bv;

        memset(buf, 0, sizeof(*buf));
        buf->rq = rq;
        buf->bio = bio;
        buf->resid = bio->bi_size;
        buf->sector = bio->bi_sector;
        bio_pageinc(bio);
        buf->bv = bv = &bio->bi_io_vec[bio->bi_idx];
        buf->bv_resid = bv->bv_len;
        WARN_ON(buf->bv_resid == 0);
}

static struct buf *
nextbuf(struct aoedev *d)
{
        struct request *rq;
        struct request_queue *q;
        struct buf *buf;
        struct bio *bio;

        q = d->blkq;
        if (q == NULL)
                return NULL;    /* initializing */
        if (d->ip.buf)
                return d->ip.buf;
        rq = d->ip.rq;
        if (rq == NULL) {
                rq = blk_peek_request(q);
                if (rq == NULL)
                        return NULL;
                blk_start_request(rq);
                d->ip.rq = rq;
                d->ip.nxbio = rq->bio;
                rq->special = (void *) rqbiocnt(rq);
        }
        buf = mempool_alloc(d->bufpool, GFP_ATOMIC);
        if (buf == NULL) {
                pr_err("aoe: nextbuf: unable to mempool_alloc!\n");
                return NULL;
        }
        bio = d->ip.nxbio;
        bufinit(buf, rq, bio);
        bio = bio->bi_next;
        d->ip.nxbio = bio;
        if (bio == NULL)
                d->ip.rq = NULL;
        return d->ip.buf = buf;
}

/* enters with d->lock held */
void
aoecmd_work(struct aoedev *d)
{
        if (d->htgt && !sthtith(d))
                return;
        while (aoecmd_ata_rw(d))
                ;
}

/* this function performs work that has been deferred until sleeping is OK
 */
void
aoecmd_sleepwork(struct work_struct *work)
{
        struct aoedev *d = container_of(work, struct aoedev, work);

        if (d->flags & DEVFL_GDALLOC)
                aoeblk_gdalloc(d);

        if (d->flags & DEVFL_NEWSIZE) {
                struct block_device *bd;
                unsigned long flags;
                u64 ssize;

                ssize = get_capacity(d->gd);
                bd = bdget_disk(d->gd, 0);

                if (bd) {
                        mutex_lock(&bd->bd_inode->i_mutex);
                        i_size_write(bd->bd_inode, (loff_t)ssize<<9);
                        mutex_unlock(&bd->bd_inode->i_mutex);
                        bdput(bd);
                }
                spin_lock_irqsave(&d->lock, flags);
                d->flags |= DEVFL_UP;
                d->flags &= ~DEVFL_NEWSIZE;
                spin_unlock_irqrestore(&d->lock, flags);
        }
}

static void
ataid_complete(struct aoedev *d, struct aoetgt *t, unsigned char *id)
{
        u64 ssize;
        u16 n;

        /* word 83: command set supported */
        n = get_unaligned_le16(&id[83 << 1]);

        /* word 86: command set/feature enabled */
        n |= get_unaligned_le16(&id[86 << 1]);

        if (n & (1<<10)) {      /* bit 10: LBA 48 */
                d->flags |= DEVFL_EXT;

                /* word 100: number lba48 sectors */
                ssize = get_unaligned_le64(&id[100 << 1]);

                /* set as in ide-disk.c:init_idedisk_capacity */
                d->geo.cylinders = ssize;
                d->geo.cylinders /= (255 * 63);
                d->geo.heads = 255;
                d->geo.sectors = 63;
        } else {
                d->flags &= ~DEVFL_EXT;

                /* number lba28 sectors */
                ssize = get_unaligned_le32(&id[60 << 1]);

                /* NOTE: obsolete in ATA 6 */
                d->geo.cylinders = get_unaligned_le16(&id[54 << 1]);
                d->geo.heads = get_unaligned_le16(&id[55 << 1]);
                d->geo.sectors = get_unaligned_le16(&id[56 << 1]);
        }

        if (d->ssize != ssize)
                printk(KERN_INFO
                        "aoe: %pm e%ld.%d v%04x has %llu sectors\n",
                        t->addr,
                        d->aoemajor, d->aoeminor,
                        d->fw_ver, (long long)ssize);
        d->ssize = ssize;
        d->geo.start = 0;
        if (d->flags & (DEVFL_GDALLOC|DEVFL_NEWSIZE))
                return;
        if (d->gd != NULL) {
                set_capacity(d->gd, ssize);
                d->flags |= DEVFL_NEWSIZE;
        } else
                d->flags |= DEVFL_GDALLOC;
        schedule_work(&d->work);
}

static void
calc_rttavg(struct aoedev *d, int rtt)
{
        register long n;

        n = rtt;
        if (n < 0) {
                n = -rtt;
                if (n < MINTIMER)
                        n = MINTIMER;
                else if (n > MAXTIMER)
                        n = MAXTIMER;
                d->mintimer += (n - d->mintimer) >> 1;
        } else if (n < d->mintimer)
                n = d->mintimer;
        else if (n > MAXTIMER)
                n = MAXTIMER;

        /* g == .25; cf. Congestion Avoidance and Control, Jacobson & Karels; 1988 */
        n -= d->rttavg;
        d->rttavg += n >> 2;
}

static struct aoetgt *
gettgt(struct aoedev *d, char *addr)
{
        struct aoetgt **t, **e;

        t = d->targets;
        e = t + NTARGETS;
        for (; t < e && *t; t++)
                if (memcmp((*t)->addr, addr, sizeof((*t)->addr)) == 0)
                        return *t;
        return NULL;
}

static void
bvcpy(struct bio_vec *bv, ulong off, struct sk_buff *skb, long cnt)
{
        ulong fcnt;
        char *p;
        int soff = 0;
loop:
        fcnt = bv->bv_len - (off - bv->bv_offset);
        if (fcnt > cnt)
                fcnt = cnt;
        p = page_address(bv->bv_page) + off;
        skb_copy_bits(skb, soff, p, fcnt);
        soff += fcnt;
        cnt -= fcnt;
        if (cnt <= 0)
                return;
        bv++;
        off = bv->bv_offset;
        goto loop;
}

void
aoe_end_request(struct aoedev *d, struct request *rq, int fastfail)
{
        struct bio *bio;
        int bok;
        struct request_queue *q;

        q = d->blkq;
        if (rq == d->ip.rq)
                d->ip.rq = NULL;
        do {
                bio = rq->bio;
                bok = !fastfail && test_bit(BIO_UPTODATE, &bio->bi_flags);
        } while (__blk_end_request(rq, bok ? 0 : -EIO, bio->bi_size));

        /* cf. http://lkml.org/lkml/2006/10/31/28 */
        if (!fastfail)
                q->request_fn(q);
}

static void
aoe_end_buf(struct aoedev *d, struct buf *buf)
{
        struct request *rq;
        unsigned long n;

        if (buf == d->ip.buf)
                d->ip.buf = NULL;
        rq = buf->rq;
        bio_pagedec(buf->bio);
        mempool_free(buf, d->bufpool);
        n = (unsigned long) rq->special;
        rq->special = (void *) --n;
        if (n == 0)
                aoe_end_request(d, rq, 0);
}

static void
ktiocomplete(struct frame *f)
{
        struct aoe_hdr *hin, *hout;
        struct aoe_atahdr *ahin, *ahout;
        struct buf *buf;
        struct sk_buff *skb;
        struct aoetgt *t;
        struct aoeif *ifp;
        struct aoedev *d;
        long n;

        if (f == NULL)
                return;

        t = f->t;
        d = t->d;

        hout = (struct aoe_hdr *) skb_mac_header(f->skb);
        ahout = (struct aoe_atahdr *) (hout+1);
        buf = f->buf;
        skb = f->r_skb;
        if (skb == NULL)
                goto noskb;     /* just fail the buf. */

        hin = (struct aoe_hdr *) skb->data;
        skb_pull(skb, sizeof(*hin));
        ahin = (struct aoe_atahdr *) skb->data;
        skb_pull(skb, sizeof(*ahin));
        if (ahin->cmdstat & 0xa9) {     /* these bits cleared on success */
                pr_err("aoe: ata error cmd=%2.2Xh stat=%2.2Xh from e%ld.%d\n",
                        ahout->cmdstat, ahin->cmdstat,
                        d->aoemajor, d->aoeminor);
noskb:  if (buf)
                        clear_bit(BIO_UPTODATE, &buf->bio->bi_flags);
                goto badrsp;
        }

        n = ahout->scnt << 9;
        switch (ahout->cmdstat) {
        case ATA_CMD_PIO_READ:
        case ATA_CMD_PIO_READ_EXT:
                if (skb->len < n) {
                        pr_err("aoe: runt data size in read.  skb->len=%d need=%ld\n",
                                skb->len, n);
                        clear_bit(BIO_UPTODATE, &buf->bio->bi_flags);
                        break;
                }
                bvcpy(f->bv, f->bv_off, skb, n);
        case ATA_CMD_PIO_WRITE:
        case ATA_CMD_PIO_WRITE_EXT:
                spin_lock_irq(&d->lock);
                ifp = getif(t, skb->dev);
                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);
                break;
        case ATA_CMD_ID_ATA:
                if (skb->len < 512) {
                        pr_info("aoe: runt data size in ataid.  skb->len=%d\n",
                                skb->len);
                        break;
                }
                if (skb_linearize(skb))
                        break;
                spin_lock_irq(&d->lock);
                ataid_complete(d, t, skb->data);
                spin_unlock_irq(&d->lock);
                break;
        default:
                pr_info("aoe: unrecognized ata command %2.2Xh for %d.%d\n",
                        ahout->cmdstat,
                        be16_to_cpu(get_unaligned(&hin->major)),
                        hin->minor);
        }
badrsp:
        spin_lock_irq(&d->lock);

        aoe_freetframe(f);

        if (buf && --buf->nframesout == 0 && buf->resid == 0)
                aoe_end_buf(d, buf);

        aoecmd_work(d);

        spin_unlock_irq(&d->lock);
        aoedev_put(d);
        dev_kfree_skb(skb);
}

/* Enters with iocq.lock held.
 * Returns true iff responses needing processing remain.
 */
static int
ktio(void)
{
        struct frame *f;
        struct list_head *pos;
        int i;

        for (i = 0; ; ++i) {
                if (i == MAXIOC)
                        return 1;
                if (list_empty(&iocq.head))
                        return 0;
                pos = iocq.head.next;
                list_del(pos);
                spin_unlock_irq(&iocq.lock);
                f = list_entry(pos, struct frame, head);
                ktiocomplete(f);
                spin_lock_irq(&iocq.lock);
        }
}

static int
kthread(void *vp)
{
        struct ktstate *k;
        DECLARE_WAITQUEUE(wait, current);
        int more;

        k = vp;
        current->flags |= PF_NOFREEZE;
        set_user_nice(current, -10);
        complete(&k->rendez);   /* tell spawner we're running */
        do {
                spin_lock_irq(k->lock);
                more = k->fn();
                if (!more) {
                        add_wait_queue(k->waitq, &wait);
                        __set_current_state(TASK_INTERRUPTIBLE);
                }
                spin_unlock_irq(k->lock);
                if (!more) {
                        schedule();
                        remove_wait_queue(k->waitq, &wait);
                } else
                        cond_resched();
        } while (!kthread_should_stop());
        complete(&k->rendez);   /* tell spawner we're stopping */
        return 0;
}

void
aoe_ktstop(struct ktstate *k)
{
        kthread_stop(k->task);
        wait_for_completion(&k->rendez);
}

int
aoe_ktstart(struct ktstate *k)
{
        struct task_struct *task;

        init_completion(&k->rendez);
        task = kthread_run(kthread, k, k->name);
        if (task == NULL || IS_ERR(task))
                return -ENOMEM;
        k->task = task;
        wait_for_completion(&k->rendez); /* allow kthread to start */
        init_completion(&k->rendez);    /* for waiting for exit later */
        return 0;
}

/* pass it off to kthreads for processing */
static void
ktcomplete(struct frame *f, struct sk_buff *skb)
{
        ulong flags;

        f->r_skb = skb;
        spin_lock_irqsave(&iocq.lock, flags);
        list_add_tail(&f->head, &iocq.head);
        spin_unlock_irqrestore(&iocq.lock, flags);
        wake_up(&ktiowq);
}

struct sk_buff *
aoecmd_ata_rsp(struct sk_buff *skb)
{
        struct aoedev *d;
        struct aoe_hdr *h;
        struct frame *f;
        struct aoetgt *t;
        u32 n;
        ulong flags;
        char ebuf[128];
        u16 aoemajor;

        h = (struct aoe_hdr *) skb->data;
        aoemajor = be16_to_cpu(get_unaligned(&h->major));
        d = aoedev_by_aoeaddr(aoemajor, h->minor);
        if (d == NULL) {
                snprintf(ebuf, sizeof ebuf, "aoecmd_ata_rsp: ata response "
                        "for unknown device %d.%d\n",
                        aoemajor, h->minor);
                aoechr_error(ebuf);
                return skb;
        }

        spin_lock_irqsave(&d->lock, flags);

        n = be32_to_cpu(get_unaligned(&h->tag));
        t = gettgt(d, h->src);
        if (t == NULL) {
                printk(KERN_INFO "aoe: can't find target e%ld.%d:%pm\n",
                       d->aoemajor, d->aoeminor, h->src);
                spin_unlock_irqrestore(&d->lock, flags);
                aoedev_put(d);
                return skb;
        }
        f = getframe(t, n);
        if (f == NULL) {
                calc_rttavg(d, -tsince(n));
                spin_unlock_irqrestore(&d->lock, flags);
                aoedev_put(d);
                snprintf(ebuf, sizeof ebuf,
                        "%15s e%d.%d    tag=%08x@%08lx\n",
                        "unexpected rsp",
                        get_unaligned_be16(&h->major),
                        h->minor,
                        get_unaligned_be32(&h->tag),
                        jiffies);
                aoechr_error(ebuf);
                return skb;
        }
        calc_rttavg(d, tsince(f->tag));
        t->nout--;
        aoecmd_work(d);

        spin_unlock_irqrestore(&d->lock, flags);

        ktcomplete(f, skb);

        /*
         * Note here that we do not perform an aoedev_put, as we are
         * leaving this reference for the ktio to release.
         */
        return NULL;
}

void
aoecmd_cfg(ushort aoemajor, unsigned char aoeminor)
{
        struct sk_buff_head queue;

        __skb_queue_head_init(&queue);
        aoecmd_cfg_pkts(aoemajor, aoeminor, &queue);
        aoenet_xmit(&queue);
}
 
struct sk_buff *
aoecmd_ata_id(struct aoedev *d)
{
        struct aoe_hdr *h;
        struct aoe_atahdr *ah;
        struct frame *f;
        struct sk_buff *skb;
        struct aoetgt *t;

        f = newframe(d);
        if (f == NULL)
                return NULL;

        t = *d->tgt;

        /* initialize the headers & frame */
        skb = f->skb;
        h = (struct aoe_hdr *) skb_mac_header(skb);
        ah = (struct aoe_atahdr *) (h+1);
        skb_put(skb, sizeof *h + sizeof *ah);
        memset(h, 0, skb->len);
        f->tag = aoehdr_atainit(d, t, h);
        fhash(f);
        t->nout++;
        f->waited = 0;

        /* set up ata header */
        ah->scnt = 1;
        ah->cmdstat = ATA_CMD_ID_ATA;
        ah->lba3 = 0xa0;

        skb->dev = t->ifp->nd;

        d->rttavg = MAXTIMER;
        d->timer.function = rexmit_timer;

        return skb_clone(skb, GFP_ATOMIC);
}
 
static struct aoetgt *
addtgt(struct aoedev *d, char *addr, ulong nframes)
{
        struct aoetgt *t, **tt, **te;
        int i;

        tt = d->targets;
        te = tt + NTARGETS;
        for (; tt < te && *tt; tt++)
                ;

        if (tt == te) {
                printk(KERN_INFO
                        "aoe: device addtgt failure; too many targets\n");
                return NULL;
        }
        t = kzalloc(sizeof(*t), GFP_ATOMIC);
        if (!t) {
                printk(KERN_INFO "aoe: cannot allocate memory to add target\n");
                return NULL;
        }

        d->ntargets++;
        t->nframes = nframes;
        t->d = d;
        memcpy(t->addr, addr, sizeof t->addr);
        t->ifp = t->ifs;
        t->maxout = t->nframes;
        INIT_LIST_HEAD(&t->ffree);
        for (i = 0; i < NFACTIVE; ++i)
                INIT_LIST_HEAD(&t->factive[i]);
        return *tt = t;
}

void
aoecmd_cfg_rsp(struct sk_buff *skb)
{
        struct aoedev *d;
        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;
        u16 n;

        sl = NULL;
        h = (struct aoe_hdr *) skb_mac_header(skb);
        ch = (struct aoe_cfghdr *) (h+1);

        /*
         * Enough people have their dip switches set backwards to
         * warrant a loud message for this special case.
         */
        aoemajor = get_unaligned_be16(&h->major);
        if (aoemajor == 0xfff) {
                printk(KERN_ERR "aoe: Warning: shelf address is all ones.  "
                        "Check shelf dip switches.\n");
                return;
        }

        sysminor = SYSMINOR(aoemajor, h->minor);
        if (sysminor * AOE_PARTITIONS + AOE_PARTITIONS > MINORMASK) {
                printk(KERN_INFO "aoe: e%ld.%d: minor number too large\n",
                        aoemajor, (int) h->minor);
                return;
        }

        n = be16_to_cpu(ch->bufcnt);
        if (n > aoe_maxout)     /* keep it reasonable */
                n = aoe_maxout;

        d = aoedev_by_sysminor_m(sysminor);
        if (d == NULL) {
                printk(KERN_INFO "aoe: device sysminor_m failure\n");
                return;
        }

        spin_lock_irqsave(&d->lock, flags);

        t = gettgt(d, h->src);
        if (!t) {
                t = addtgt(d, h->src, n);
                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;
                }
        }

        /* don't change users' perspective */
        if (d->nopen == 0) {
                d->fw_ver = be16_to_cpu(ch->fwver);
                sl = aoecmd_ata_id(d);
        }
bail:
        spin_unlock_irqrestore(&d->lock, flags);
        aoedev_put(d);
        if (sl) {
                __skb_queue_head_init(&queue);
                __skb_queue_tail(&queue, sl);
                aoenet_xmit(&queue);
        }
}

void
aoecmd_cleanslate(struct aoedev *d)
{
        struct aoetgt **t, **te;
        struct aoeif *p, *e;

        d->mintimer = MINTIMER;

        t = d->targets;
        te = t + NTARGETS;
        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
aoe_failbuf(struct aoedev *d, struct buf *buf)
{
        if (buf == NULL)
                return;
        buf->resid = 0;
        clear_bit(BIO_UPTODATE, &buf->bio->bi_flags);
        if (buf->nframesout == 0)
                aoe_end_buf(d, buf);
}

void
aoe_flush_iocq(void)
{
        struct frame *f;
        struct aoedev *d;
        LIST_HEAD(flist);
        struct list_head *pos;
        struct sk_buff *skb;
        ulong flags;

        spin_lock_irqsave(&iocq.lock, flags);
        list_splice_init(&iocq.head, &flist);
        spin_unlock_irqrestore(&iocq.lock, flags);
        while (!list_empty(&flist)) {
                pos = flist.next;
                list_del(pos);
                f = list_entry(pos, struct frame, head);
                d = f->t->d;
                skb = f->r_skb;
                spin_lock_irqsave(&d->lock, flags);
                if (f->buf) {
                        f->buf->nframesout--;
                        aoe_failbuf(d, f->buf);
                }
                aoe_freetframe(f);
                spin_unlock_irqrestore(&d->lock, flags);
                dev_kfree_skb(skb);
                aoedev_put(d);
        }
}

int __init
aoecmd_init(void)
{
        INIT_LIST_HEAD(&iocq.head);
        spin_lock_init(&iocq.lock);
        init_waitqueue_head(&ktiowq);
        kts.name = "aoe_ktio";
        kts.fn = ktio;
        kts.waitq = &ktiowq;
        kts.lock = &iocq.lock;
        return aoe_ktstart(&kts);
}

void
aoecmd_exit(void)
{
        aoe_ktstop(&kts);
        aoe_flush_iocq();
}