aoe: improve retransmission heuristics

[linux-2.6.22.y-op.git] / drivers / block / aoe / aoecmd.c

/* Copyright (c) 2006 Coraid, Inc.  See COPYING for GPL terms. */
/*
 * aoecmd.c
 * Filesystem request handling methods
 */

#include <linux/hdreg.h>
#include <linux/blkdev.h>
#include <linux/skbuff.h>
#include <linux/netdevice.h>
#include <linux/genhd.h>
#include <asm/unaligned.h>
#include "aoe.h"

#define TIMERTICK (HZ / 10)
#define MINTIMER (2 * TIMERTICK)
#define MAXTIMER (HZ << 1)
#define MAXWAIT (60 * 3)        /* After MAXWAIT seconds, give up and fail dev */

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

        skb = alloc_skb(len, GFP_ATOMIC);
        if (skb) {
                skb->nh.raw = skb->mac.raw = skb->data;
                skb->protocol = __constant_htons(ETH_P_AOE);
                skb->priority = 0;
                skb_put(skb, len);
                memset(skb->head, 0, len);
                skb->next = skb->prev = NULL;

                /* tell the network layer not to perform IP checksums
                 * or to get the NIC to do it
                 */
                skb->ip_summed = CHECKSUM_NONE;
        }
        return skb;
}

static struct frame *
getframe(struct aoedev *d, int tag)
{
        struct frame *f, *e;

        f = d->frames;
        e = f + d->nframes;
        for (; f<e; f++)
                if (f->tag == tag)
                        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 aoedev *d)
{
        register ulong n;

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

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

        memcpy(h->src, d->ifp->dev_addr, sizeof h->src);
        memcpy(h->dst, d->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
aoecmd_ata_rw(struct aoedev *d, struct frame *f)
{
        struct aoe_hdr *h;
        struct aoe_atahdr *ah;
        struct buf *buf;
        struct sk_buff *skb;
        ulong bcnt;
        register sector_t sector;
        char writebit, extbit;

        writebit = 0x10;
        extbit = 0x4;

        buf = d->inprocess;

        sector = buf->sector;
        bcnt = buf->bv_resid;
        if (bcnt > d->maxbcnt)
                bcnt = d->maxbcnt;

        /* initialize the headers & frame */
        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);
        f->tag = aoehdr_atainit(d, h);
        f->waited = 0;
        f->buf = buf;
        f->bufaddr = buf->bufaddr;
        f->bcnt = bcnt;
        f->lba = sector;

        /* set up ata header */
        ah->scnt = bcnt >> 9;
        put_lba(ah, 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_fill_page_desc(skb, 0, virt_to_page(f->bufaddr),
                        offset_in_page(f->bufaddr), bcnt);
                ah->aflags |= AOEAFL_WRITE;
        } else {
                skb_shinfo(skb)->nr_frags = 0;
                skb->len = ETH_ZLEN;
                writebit = 0;
        }

        ah->cmdstat = WIN_READ | writebit | extbit;

        /* mark all tracking fields and load out */
        buf->nframesout += 1;
        buf->bufaddr += bcnt;
        buf->bv_resid -= bcnt;
/* dprintk("bv_resid=%ld\n", buf->bv_resid); */
        buf->resid -= bcnt;
        buf->sector += bcnt >> 9;
        if (buf->resid == 0) {
                d->inprocess = NULL;
        } else if (buf->bv_resid == 0) {
                buf->bv++;
                buf->bv_resid = buf->bv->bv_len;
                buf->bufaddr = page_address(buf->bv->bv_page) + buf->bv->bv_offset;
        }

        skb->dev = d->ifp;
        skb_get(skb);
        skb->next = NULL;
        if (d->sendq_hd)
                d->sendq_tl->next = skb;
        else
                d->sendq_hd = skb;
        d->sendq_tl = skb;
}

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

        sl = sl_tail = NULL;

        read_lock(&dev_base_lock);
        for (ifp = dev_base; ifp; dev_put(ifp), ifp = ifp->next) {
                dev_hold(ifp);
                if (!is_aoe_netif(ifp))
                        continue;

                skb = new_skb(sizeof *h + sizeof *ch);
                if (skb == NULL) {
                        iprintk("skb alloc failure\n");
                        continue;
                }
                skb->dev = ifp;
                if (sl_tail == NULL)
                        sl_tail = skb;
                h = (struct aoe_hdr *) skb->mac.raw;
                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;

                skb->next = sl;
                sl = skb;
        }
        read_unlock(&dev_base_lock);

        if (tail != NULL)
                *tail = sl_tail;
        return sl;
}

/* enters with d->lock held */
void
aoecmd_work(struct aoedev *d)
{
        struct frame *f;
        struct buf *buf;

        if (d->flags & DEVFL_PAUSE) {
                if (!aoedev_isbusy(d))
                        d->sendq_hd = aoecmd_cfg_pkts(d->aoemajor,
                                                d->aoeminor, &d->sendq_tl);
                return;
        }

loop:
        f = getframe(d, FREETAG);
        if (f == NULL)
                return;
        if (d->inprocess == NULL) {
                if (list_empty(&d->bufq))
                        return;
                buf = container_of(d->bufq.next, struct buf, bufs);
                list_del(d->bufq.next);
/*dprintk("bi_size=%ld\n", buf->bio->bi_size); */
                d->inprocess = buf;
        }
        aoecmd_ata_rw(d, f);
        goto loop;
}

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

        n = newtag(d);

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

        skb = f->skb;
        h = (struct aoe_hdr *) skb->mac.raw;
        ah = (struct aoe_atahdr *) (h+1);
        f->tag = n;
        h->tag = cpu_to_be32(n);
        memcpy(h->dst, d->addr, sizeof h->dst);
        memcpy(h->src, d->ifp->dev_addr, sizeof h->src);

        n = DEFAULTBCNT / 512;
        if (ah->scnt > n) {
                ah->scnt = n;
                if (ah->aflags & AOEAFL_WRITE)
                        skb_fill_page_desc(skb, 0, virt_to_page(f->bufaddr),
                                offset_in_page(f->bufaddr), DEFAULTBCNT);
                if (++d->lostjumbo > (d->nframes << 1))
                if (d->maxbcnt != DEFAULTBCNT) {
                        iprintk("too many lost jumbo - using 1KB frames.\n");
                        d->maxbcnt = DEFAULTBCNT;
                        d->flags |= DEVFL_MAXBCNT;
                }
        }

        skb->dev = d->ifp;
        skb_get(skb);
        skb->next = NULL;
        if (d->sendq_hd)
                d->sendq_tl->next = skb;
        else
                d->sendq_hd = skb;
        d->sendq_tl = skb;
}

static int
tsince(int tag)
{
        int n;

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

static void
rexmit_timer(ulong vp)
{
        struct aoedev *d;
        struct frame *f, *e;
        struct sk_buff *sl;
        register long timeout;
        ulong flags, n;

        d = (struct aoedev *) vp;
        sl = NULL;

        /* 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;
        }
        f = d->frames;
        e = f + d->nframes;
        for (; f<e; f++) {
                if (f->tag != FREETAG && tsince(f->tag) >= timeout) {
                        n = f->waited += timeout;
                        n /= HZ;
                        if (n > MAXWAIT) { /* waited too long.  device failure. */
                                aoedev_downdev(d);
                                break;
                        }
                        rexmit(d, f);
                }
        }

        sl = d->sendq_hd;
        d->sendq_hd = d->sendq_tl = NULL;
        if (sl) {
                n = d->rttavg <<= 1;
                if (n > MAXTIMER)
                        d->rttavg = MAXTIMER;
        }

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

        spin_unlock_irqrestore(&d->lock, flags);

        aoenet_xmit(sl);
}

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

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

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

                ssize = d->gd->capacity;
                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, unsigned char *id)
{
        u64 ssize;
        u16 n;

        /* word 83: command set supported */
        n = le16_to_cpu(get_unaligned((__le16 *) &id[83<<1]));

        /* word 86: command set/feature enabled */
        n |= le16_to_cpu(get_unaligned((__le16 *) &id[86<<1]));

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

                /* word 100: number lba48 sectors */
                ssize = le64_to_cpu(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 = le32_to_cpu(get_unaligned((__le32 *) &id[60<<1]));

                /* NOTE: obsolete in ATA 6 */
                d->geo.cylinders = le16_to_cpu(get_unaligned((__le16 *) &id[54<<1]));
                d->geo.heads = le16_to_cpu(get_unaligned((__le16 *) &id[55<<1]));
                d->geo.sectors = le16_to_cpu(get_unaligned((__le16 *) &id[56<<1]));
        }

        if (d->ssize != ssize)
                iprintk("%012llx e%lu.%lu v%04x has %llu sectors\n",
                        (unsigned long long)mac_addr(d->addr),
                        d->aoemajor, d->aoeminor,
                        d->fw_ver, (long long)ssize);
        d->ssize = ssize;
        d->geo.start = 0;
        if (d->gd != NULL) {
                d->gd->capacity = ssize;
                d->flags |= DEVFL_NEWSIZE;
        } else {
                if (d->flags & DEVFL_GDALLOC) {
                        eprintk("can't schedule work for e%lu.%lu, %s\n",
                               d->aoemajor, d->aoeminor,
                               "it's already on!  This shouldn't happen.\n");
                        return;
                }
                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;
}

void
aoecmd_ata_rsp(struct sk_buff *skb)
{
        struct aoedev *d;
        struct aoe_hdr *hin, *hout;
        struct aoe_atahdr *ahin, *ahout;
        struct frame *f;
        struct buf *buf;
        struct sk_buff *sl;
        register long n;
        ulong flags;
        char ebuf[128];
        u16 aoemajor;

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

        spin_lock_irqsave(&d->lock, flags);

        n = be32_to_cpu(hin->tag);
        f = getframe(d, n);
        if (f == NULL) {
                calc_rttavg(d, -tsince(n));
                spin_unlock_irqrestore(&d->lock, flags);
                snprintf(ebuf, sizeof ebuf,
                        "%15s e%d.%d    tag=%08x@%08lx\n",
                        "unexpected rsp",
                        be16_to_cpu(hin->major),
                        hin->minor,
                        be32_to_cpu(hin->tag),
                        jiffies);
                aoechr_error(ebuf);
                return;
        }

        calc_rttavg(d, tsince(f->tag));

        ahin = (struct aoe_atahdr *) (hin+1);
        hout = (struct aoe_hdr *) f->skb->mac.raw;
        ahout = (struct aoe_atahdr *) (hout+1);
        buf = f->buf;

        if (ahout->cmdstat == WIN_IDENTIFY)
                d->flags &= ~DEVFL_PAUSE;
        if (ahin->cmdstat & 0xa9) {     /* these bits cleared on success */
                eprintk("ata error cmd=%2.2Xh stat=%2.2Xh from e%ld.%ld\n",
                        ahout->cmdstat, ahin->cmdstat,
                        d->aoemajor, d->aoeminor);
                if (buf)
                        buf->flags |= BUFFL_FAIL;
        } else {
                n = ahout->scnt << 9;
                switch (ahout->cmdstat) {
                case WIN_READ:
                case WIN_READ_EXT:
                        if (skb->len - sizeof *hin - sizeof *ahin < n) {
                                eprintk("runt data size in read.  skb->len=%d\n",
                                        skb->len);
                                /* fail frame f?  just returning will rexmit. */
                                spin_unlock_irqrestore(&d->lock, flags);
                                return;
                        }
                        memcpy(f->bufaddr, ahin+1, n);
                case WIN_WRITE:
                case WIN_WRITE_EXT:
                        if (f->bcnt -= n) {
                                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,
                                                virt_to_page(f->bufaddr),
                                                offset_in_page(f->bufaddr), n);
                                f->tag = newtag(d);
                                hout->tag = cpu_to_be32(f->tag);
                                skb->dev = d->ifp;
                                skb_get(f->skb);
                                f->skb->next = NULL;
                                spin_unlock_irqrestore(&d->lock, flags);
                                aoenet_xmit(f->skb);
                                return;
                        }
                        if (n > DEFAULTBCNT)
                                d->lostjumbo = 0;
                        break;
                case WIN_IDENTIFY:
                        if (skb->len - sizeof *hin - sizeof *ahin < 512) {
                                iprintk("runt data size in ataid.  skb->len=%d\n",
                                        skb->len);
                                spin_unlock_irqrestore(&d->lock, flags);
                                return;
                        }
                        ataid_complete(d, (char *) (ahin+1));
                        break;
                default:
                        iprintk("unrecognized ata command %2.2Xh for %d.%d\n",
                                ahout->cmdstat,
                                be16_to_cpu(hin->major),
                                hin->minor);
                }
        }

        if (buf) {
                buf->nframesout -= 1;
                if (buf->nframesout == 0 && buf->resid == 0) {
                        unsigned long duration = jiffies - buf->start_time;
                        unsigned long n_sect = buf->bio->bi_size >> 9;
                        struct gendisk *disk = d->gd;
                        const int rw = bio_data_dir(buf->bio);

                        disk_stat_inc(disk, ios[rw]);
                        disk_stat_add(disk, ticks[rw], duration);
                        disk_stat_add(disk, sectors[rw], n_sect);
                        disk_stat_add(disk, io_ticks, duration);
                        n = (buf->flags & BUFFL_FAIL) ? -EIO : 0;
                        bio_endio(buf->bio, buf->bio->bi_size, n);
                        mempool_free(buf, d->bufpool);
                }
        }

        f->buf = NULL;
        f->tag = FREETAG;

        aoecmd_work(d);
        sl = d->sendq_hd;
        d->sendq_hd = d->sendq_tl = NULL;

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

void
aoecmd_cfg(ushort aoemajor, unsigned char aoeminor)
{
        struct sk_buff *sl;

        sl = aoecmd_cfg_pkts(aoemajor, aoeminor, NULL);

        aoenet_xmit(sl);
}
 
/*
 * Since we only call this in one place (and it only prepares one frame)
 * we just return the skb.  Usually we'd chain it up to the aoedev sendq.
 */
static struct sk_buff *
aoecmd_ata_id(struct aoedev *d)
{
        struct aoe_hdr *h;
        struct aoe_atahdr *ah;
        struct frame *f;
        struct sk_buff *skb;

        f = getframe(d, FREETAG);
        if (f == NULL) {
                eprintk("can't get a frame. This shouldn't happen.\n");
                return NULL;
        }

        /* initialize the headers & frame */
        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);
        f->tag = aoehdr_atainit(d, h);
        f->waited = 0;

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

        skb->dev = d->ifp;
        skb_get(skb);

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

        return skb;
}
 
void
aoecmd_cfg_rsp(struct sk_buff *skb)
{
        struct aoedev *d;
        struct aoe_hdr *h;
        struct aoe_cfghdr *ch;
        ulong flags, sysminor, aoemajor;
        struct sk_buff *sl;
        enum { MAXFRAMES = 16 };
        u16 n;

        h = (struct aoe_hdr *) skb->mac.raw;
        ch = (struct aoe_cfghdr *) (h+1);

        /*
         * Enough people have their dip switches set backwards to
         * warrant a loud message for this special case.
         */
        aoemajor = be16_to_cpu(h->major);
        if (aoemajor == 0xfff) {
                eprintk("Warning: shelf address is all ones.  "
                        "Check shelf dip switches.\n");
                return;
        }

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

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

        d = aoedev_by_sysminor_m(sysminor, n);
        if (d == NULL) {
                iprintk("device sysminor_m failure\n");
                return;
        }

        spin_lock_irqsave(&d->lock, flags);

        /* permit device to migrate mac and network interface */
        d->ifp = skb->dev;
        memcpy(d->addr, h->src, sizeof d->addr);
        if (!(d->flags & DEVFL_MAXBCNT)) {
                n = d->ifp->mtu;
                n -= sizeof (struct aoe_hdr) + sizeof (struct aoe_atahdr);
                n /= 512;
                if (n > ch->scnt)
                        n = ch->scnt;
                d->maxbcnt = n ? n * 512 : DEFAULTBCNT;
        }

        /* don't change users' perspective */
        if (d->nopen && !(d->flags & DEVFL_PAUSE)) {
                spin_unlock_irqrestore(&d->lock, flags);
                return;
        }
        d->flags |= DEVFL_PAUSE;        /* force pause */
        d->mintimer = MINTIMER;
        d->fw_ver = be16_to_cpu(ch->fwver);

        /* check for already outstanding ataid */
        sl = aoedev_isbusy(d) == 0 ? aoecmd_ata_id(d) : NULL;

        spin_unlock_irqrestore(&d->lock, flags);

        aoenet_xmit(sl);
}