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Subject[PATCH 03/14] aoe: become I/O request queue handler for increased user control
To allow users to choose an elevator algorithm for their particular
workloads, change from a make_request-style driver to an
I/O-request-queue-handler-style driver.

We have to do a couple of things that might be surprising. We
manipulate the page _count directly on the assumption that we still
have no guarantee that users of the block layer are prohibited from
submitting bios containing pages with zero reference counts.[1] If
such a prohibition now exists, I can get rid of the _count
manipulation.

Just as before this patch, we still keep track of the sk_buffs that
the network layer still hasn't finished yet and cap the resources we
use with a "pool" of skbs.[2]

Now that the block layer maintains the disk stats, the aoe driver's
diskstats function can go away.

1. https://lkml.org/lkml/2007/3/1/374
2. https://lkml.org/lkml/2007/7/6/241

Signed-off-by: Ed Cashin <ecashin@coraid.com>
---
drivers/block/aoe/aoe.h | 26 ++--
drivers/block/aoe/aoeblk.c | 88 ++++----------
drivers/block/aoe/aoechr.c | 1 +
drivers/block/aoe/aoecmd.c | 282 +++++++++++++++++++++++++++++++------------
drivers/block/aoe/aoedev.c | 93 ++++++++++-----
5 files changed, 308 insertions(+), 182 deletions(-)

diff --git a/drivers/block/aoe/aoe.h b/drivers/block/aoe/aoe.h
index 0cd6c0f..8c4f6d9 100644
--- a/drivers/block/aoe/aoe.h
+++ b/drivers/block/aoe/aoe.h
@@ -90,7 +90,7 @@ enum {
MIN_BUFS = 16,
NTARGETS = 8,
NAOEIFS = 8,
- NSKBPOOLMAX = 128,
+ NSKBPOOLMAX = 256,
NFACTIVE = 17,

TIMERTICK = HZ / 10,
@@ -100,30 +100,26 @@ enum {
};

struct buf {
- struct list_head bufs;
- ulong stime; /* for disk stats */
- ulong flags;
ulong nframesout;
ulong resid;
ulong bv_resid;
- ulong bv_off;
sector_t sector;
struct bio *bio;
struct bio_vec *bv;
+ struct request *rq;
};

struct frame {
struct list_head head;
u32 tag;
ulong waited;
- struct buf *buf;
struct aoetgt *t; /* parent target I belong to */
- char *bufaddr;
- ulong bcnt;
sector_t lba;
struct sk_buff *skb; /* command skb freed on module exit */
struct sk_buff *r_skb; /* response skb for async processing */
+ struct buf *buf;
struct bio_vec *bv;
+ ulong bcnt;
ulong bv_off;
};

@@ -161,6 +157,7 @@ struct aoedev {
u16 rttavg; /* round trip average of requests/responses */
u16 mintimer;
u16 fw_ver; /* version of blade's firmware */
+ ulong ref;
struct work_struct work;/* disk create work struct */
struct gendisk *gd;
struct request_queue *blkq;
@@ -168,11 +165,13 @@ struct aoedev {
sector_t ssize;
struct timer_list timer;
spinlock_t lock;
- struct sk_buff_head sendq;
struct sk_buff_head skbpool;
mempool_t *bufpool; /* for deadlock-free Buf allocation */
- struct list_head bufq; /* queue of bios to work on */
- struct buf *inprocess; /* the one we're currently working on */
+ struct { /* pointers to work in progress */
+ struct buf *buf;
+ struct bio *nxbio;
+ struct request *rq;
+ } ip;
struct aoetgt *targets[NTARGETS];
struct aoetgt **tgt; /* target in use when working */
struct aoetgt *htgt; /* target needing rexmit assistance */
@@ -209,6 +208,8 @@ void aoecmd_exit(void);
int aoecmd_init(void);
struct sk_buff *aoecmd_ata_id(struct aoedev *);
void aoe_freetframe(struct frame *);
+void aoe_flush_iocq(void);
+void aoe_end_request(struct aoedev *, struct request *, int);

int aoedev_init(void);
void aoedev_exit(void);
@@ -216,7 +217,8 @@ struct aoedev *aoedev_by_aoeaddr(int maj, int min);
struct aoedev *aoedev_by_sysminor_m(ulong sysminor);
void aoedev_downdev(struct aoedev *d);
int aoedev_flush(const char __user *str, size_t size);
-void aoe_failbuf(struct aoedev *d, struct buf *buf);
+void aoe_failbuf(struct aoedev *, struct buf *);
+void aoedev_put(struct aoedev *);

int aoenet_init(void);
void aoenet_exit(void);
diff --git a/drivers/block/aoe/aoeblk.c b/drivers/block/aoe/aoeblk.c
index 1471f81..7ec4b8f 100644
--- a/drivers/block/aoe/aoeblk.c
+++ b/drivers/block/aoe/aoeblk.c
@@ -161,68 +161,22 @@ aoeblk_release(struct gendisk *disk, fmode_t mode)
}

static void
-aoeblk_make_request(struct request_queue *q, struct bio *bio)
+aoeblk_request(struct request_queue *q)
{
- struct sk_buff_head queue;
struct aoedev *d;
- struct buf *buf;
- ulong flags;
-
- blk_queue_bounce(q, &bio);
-
- if (bio == NULL) {
- printk(KERN_ERR "aoe: bio is NULL\n");
- BUG();
- return;
- }
- d = bio->bi_bdev->bd_disk->private_data;
- if (d == NULL) {
- printk(KERN_ERR "aoe: bd_disk->private_data is NULL\n");
- BUG();
- bio_endio(bio, -ENXIO);
- return;
- } else if (bio->bi_io_vec == NULL) {
- printk(KERN_ERR "aoe: bi_io_vec is NULL\n");
- BUG();
- bio_endio(bio, -ENXIO);
- return;
- }
- buf = mempool_alloc(d->bufpool, GFP_NOIO);
- if (buf == NULL) {
- printk(KERN_INFO "aoe: buf allocation failure\n");
- bio_endio(bio, -ENOMEM);
- return;
- }
- memset(buf, 0, sizeof(*buf));
- INIT_LIST_HEAD(&buf->bufs);
- buf->stime = jiffies;
- buf->bio = bio;
- buf->resid = bio->bi_size;
- buf->sector = bio->bi_sector;
- buf->bv = &bio->bi_io_vec[bio->bi_idx];
- buf->bv_resid = buf->bv->bv_len;
- WARN_ON(buf->bv_resid == 0);
- buf->bv_off = buf->bv->bv_offset;
-
- spin_lock_irqsave(&d->lock, flags);
+ struct request *rq;

+ d = q->queuedata;
if ((d->flags & DEVFL_UP) == 0) {
pr_info_ratelimited("aoe: device %ld.%d is not up\n",
d->aoemajor, d->aoeminor);
- spin_unlock_irqrestore(&d->lock, flags);
- mempool_free(buf, d->bufpool);
- bio_endio(bio, -ENXIO);
+ while ((rq = blk_peek_request(q))) {
+ blk_start_request(rq);
+ aoe_end_request(d, rq, 1);
+ }
return;
}
-
- list_add_tail(&buf->bufs, &d->bufq);
-
aoecmd_work(d);
- __skb_queue_head_init(&queue);
- skb_queue_splice_init(&d->sendq, &queue);
-
- spin_unlock_irqrestore(&d->lock, flags);
- aoenet_xmit(&queue);
}

static int
@@ -254,34 +208,46 @@ aoeblk_gdalloc(void *vp)
{
struct aoedev *d = vp;
struct gendisk *gd;
+ mempool_t *mp;
+ struct request_queue *q;
+ enum { KB = 1024, MB = KB * KB, READ_AHEAD = 2 * MB, };
ulong flags;

gd = alloc_disk(AOE_PARTITIONS);
if (gd == NULL) {
- printk(KERN_ERR
- "aoe: cannot allocate disk structure for %ld.%d\n",
+ pr_err("aoe: cannot allocate disk structure for %ld.%d\n",
d->aoemajor, d->aoeminor);
goto err;
}

- d->bufpool = mempool_create_slab_pool(MIN_BUFS, buf_pool_cache);
- if (d->bufpool == NULL) {
+ mp = mempool_create(MIN_BUFS, mempool_alloc_slab, mempool_free_slab,
+ buf_pool_cache);
+ if (mp == NULL) {
printk(KERN_ERR "aoe: cannot allocate bufpool for %ld.%d\n",
d->aoemajor, d->aoeminor);
goto err_disk;
}
+ q = blk_init_queue(aoeblk_request, &d->lock);
+ if (q == NULL) {
+ pr_err("aoe: cannot allocate block queue for %ld.%d\n",
+ d->aoemajor, d->aoeminor);
+ mempool_destroy(mp);
+ goto err_disk;
+ }

d->blkq = blk_alloc_queue(GFP_KERNEL);
if (!d->blkq)
goto err_mempool;
- blk_queue_make_request(d->blkq, aoeblk_make_request);
d->blkq->backing_dev_info.name = "aoe";
if (bdi_init(&d->blkq->backing_dev_info))
goto err_blkq;
spin_lock_irqsave(&d->lock, flags);
blk_queue_max_hw_sectors(d->blkq, BLK_DEF_MAX_SECTORS);
- d->blkq->backing_dev_info.ra_pages = BLK_DEF_MAX_SECTORS * 1024;
- d->blkq->backing_dev_info.ra_pages /= PAGE_CACHE_SIZE;
+ q->backing_dev_info.ra_pages = READ_AHEAD / PAGE_CACHE_SIZE;
+ d->bufpool = mp;
+ d->blkq = gd->queue = q;
+ q->queuedata = d;
+ d->gd = gd;
gd->major = AOE_MAJOR;
gd->first_minor = d->sysminor * AOE_PARTITIONS;
gd->fops = &aoe_bdops;
@@ -290,8 +256,6 @@ aoeblk_gdalloc(void *vp)
snprintf(gd->disk_name, sizeof gd->disk_name, "etherd/e%ld.%d",
d->aoemajor, d->aoeminor);

- gd->queue = d->blkq;
- d->gd = gd;
d->flags &= ~DEVFL_GDALLOC;
d->flags |= DEVFL_UP;

diff --git a/drivers/block/aoe/aoechr.c b/drivers/block/aoe/aoechr.c
index f145388..3557f0d 100644
--- a/drivers/block/aoe/aoechr.c
+++ b/drivers/block/aoe/aoechr.c
@@ -106,6 +106,7 @@ loop:
spin_lock_irqsave(&d->lock, flags);
goto loop;
}
+ aoedev_put(d);
if (skb) {
struct sk_buff_head queue;
__skb_queue_head_init(&queue);
diff --git a/drivers/block/aoe/aoecmd.c b/drivers/block/aoe/aoecmd.c
index d0fc53f..e7df343 100644
--- a/drivers/block/aoe/aoecmd.c
+++ b/drivers/block/aoe/aoecmd.c
@@ -23,6 +23,8 @@

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.");
@@ -282,17 +284,20 @@ aoecmd_ata_rw(struct aoedev *d)
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;
- buf = d->inprocess;
bv = buf->bv;
bcnt = t->ifp->maxbcnt;
if (bcnt == 0)
@@ -311,7 +316,7 @@ aoecmd_ata_rw(struct aoedev *d)
fbcnt -= buf->bv_resid;
buf->resid -= buf->bv_resid;
if (buf->resid == 0) {
- d->inprocess = NULL;
+ d->ip.buf = NULL;
break;
}
buf->bv++;
@@ -363,8 +368,11 @@ aoecmd_ata_rw(struct aoedev *d)

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

@@ -414,6 +422,7 @@ 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;
@@ -443,7 +452,9 @@ resend(struct aoedev *d, struct frame *f)
skb = skb_clone(skb, GFP_ATOMIC);
if (skb == NULL)
return;
- __skb_queue_tail(&d->sendq, skb);
+ __skb_queue_head_init(&queue);
+ __skb_queue_tail(&queue, skb);
+ aoenet_xmit(&queue);
}

static int
@@ -553,7 +564,6 @@ ata_scnt(unsigned char *packet) {
static void
rexmit_timer(ulong vp)
{
- struct sk_buff_head queue;
struct aoedev *d;
struct aoetgt *t, **tt, **te;
struct aoeif *ifp;
@@ -602,6 +612,12 @@ rexmit_timer(ulong vp)
}
}

+ 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;
@@ -640,45 +656,131 @@ rexmit_timer(ulong vp)
resend(d, f);
}

- if (!skb_queue_empty(&d->sendq)) {
- n = d->rttavg <<= 1;
- if (n > MAXTIMER)
- d->rttavg = MAXTIMER;
- }
-
- if (d->flags & DEVFL_KICKME || d->htgt) {
+ if ((d->flags & DEVFL_KICKME || d->htgt) && d->blkq) {
d->flags &= ~DEVFL_KICKME;
- aoecmd_work(d);
+ d->blkq->request_fn(d->blkq);
}

- __skb_queue_head_init(&queue);
- skb_queue_splice_init(&d->sendq, &queue);
-
d->timer.expires = jiffies + TIMERTICK;
add_timer(&d->timer);

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

- aoenet_xmit(&queue);
+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)
{
- struct buf *buf;
-loop:
if (d->htgt && !sthtith(d))
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);
- d->inprocess = buf;
- }
- if (aoecmd_ata_rw(d))
- goto loop;
+ while (aoecmd_ata_rw(d))
+ ;
}

/* this function performs work that has been deferred until sleeping is OK
@@ -801,25 +903,6 @@ gettgt(struct aoedev *d, char *addr)
return NULL;
}

-static inline void
-diskstats(struct gendisk *disk, struct bio *bio, ulong duration, sector_t sector)
-{
- unsigned long n_sect = bio->bi_size >> 9;
- const int rw = bio_data_dir(bio);
- struct hd_struct *part;
- int cpu;
-
- cpu = part_stat_lock();
- part = disk_map_sector_rcu(disk, sector);
-
- part_stat_inc(cpu, part, ios[rw]);
- part_stat_add(cpu, part, ticks[rw], duration);
- part_stat_add(cpu, part, sectors[rw], n_sect);
- part_stat_add(cpu, part, io_ticks, duration);
-
- part_stat_unlock();
-}
-
static void
bvcpy(struct bio_vec *bv, ulong off, struct sk_buff *skb, long cnt)
{
@@ -841,6 +924,43 @@ loop:
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)
{
@@ -875,7 +995,7 @@ ktiocomplete(struct frame *f)
ahout->cmdstat, ahin->cmdstat,
d->aoemajor, d->aoeminor);
noskb: if (buf)
- buf->flags |= BUFFL_FAIL;
+ clear_bit(BIO_UPTODATE, &buf->bio->bi_flags);
goto badrsp;
}

@@ -886,7 +1006,7 @@ noskb: if (buf)
if (skb->len < n) {
pr_err("aoe: runt data size in read. skb->len=%d need=%ld\n",
skb->len, n);
- buf->flags |= BUFFL_FAIL;
+ clear_bit(BIO_UPTODATE, &buf->bio->bi_flags);
break;
}
bvcpy(f->bv, f->bv_off, skb, n);
@@ -926,18 +1046,13 @@ badrsp:

aoe_freetframe(f);

- if (buf && --buf->nframesout == 0 && buf->resid == 0) {
- struct bio *bio = buf->bio;
+ if (buf && --buf->nframesout == 0 && buf->resid == 0)
+ aoe_end_buf(d, buf);

- diskstats(d->gd, bio, jiffies - buf->stime, buf->sector);
- n = (buf->flags & BUFFL_FAIL) ? -EIO : 0;
- mempool_free(buf, d->bufpool);
- spin_unlock_irq(&d->lock);
- if (n != -EIO)
- bio_flush_dcache_pages(buf->bio);
- bio_endio(bio, n);
- } else
- spin_unlock_irq(&d->lock);
+ aoecmd_work(d);
+
+ spin_unlock_irq(&d->lock);
+ aoedev_put(d);
dev_kfree_skb(skb);
}

@@ -1068,12 +1183,14 @@ aoecmd_ata_rsp(struct sk_buff *skb)
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",
@@ -1193,8 +1310,10 @@ aoecmd_cfg_rsp(struct sk_buff *skb)
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);

@@ -1231,10 +1350,8 @@ aoecmd_cfg_rsp(struct sk_buff *skb)
t = gettgt(d, h->src);
if (!t) {
t = addtgt(d, h->src, n);
- if (!t) {
- spin_unlock_irqrestore(&d->lock, flags);
- return;
- }
+ if (!t)
+ goto bail;
}
ifp = getif(t, skb->dev);
if (!ifp) {
@@ -1243,8 +1360,7 @@ aoecmd_cfg_rsp(struct sk_buff *skb)
printk(KERN_INFO
"aoe: device addif failure; "
"too many interfaces?\n");
- spin_unlock_irqrestore(&d->lock, flags);
- return;
+ goto bail;
}
}
if (ifp->maxbcnt) {
@@ -1265,18 +1381,14 @@ aoecmd_cfg_rsp(struct sk_buff *skb)
}

/* don't change users' perspective */
- if (d->nopen) {
- spin_unlock_irqrestore(&d->lock, flags);
- return;
+ if (d->nopen == 0) {
+ d->fw_ver = be16_to_cpu(ch->fwver);
+ sl = aoecmd_ata_id(d);
}
- 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) {
- struct sk_buff_head queue;
__skb_queue_head_init(&queue);
__skb_queue_tail(&queue, sl);
aoenet_xmit(&queue);
@@ -1305,8 +1417,19 @@ aoecmd_cleanslate(struct aoedev *d)
}
}

-static void
-flush_iocq(void)
+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;
@@ -1332,6 +1455,7 @@ flush_iocq(void)
aoe_freetframe(f);
spin_unlock_irqrestore(&d->lock, flags);
dev_kfree_skb(skb);
+ aoedev_put(d);
}
}

@@ -1352,5 +1476,5 @@ void
aoecmd_exit(void)
{
aoe_ktstop(&kts);
- flush_iocq();
+ aoe_flush_iocq();
}
diff --git a/drivers/block/aoe/aoedev.c b/drivers/block/aoe/aoedev.c
index 40bae1a..635dc98 100644
--- a/drivers/block/aoe/aoedev.c
+++ b/drivers/block/aoe/aoedev.c
@@ -19,6 +19,17 @@ static void skbpoolfree(struct aoedev *d);
static struct aoedev *devlist;
static DEFINE_SPINLOCK(devlist_lock);

+/*
+ * Users who grab a pointer to the device with aoedev_by_aoeaddr or
+ * aoedev_by_sysminor_m automatically get a reference count and must
+ * be responsible for performing a aoedev_put. With the addition of
+ * async kthread processing I'm no longer confident that we can
+ * guarantee consistency in the face of device flushes.
+ *
+ * For the time being, we only bother to add extra references for
+ * frames sitting on the iocq. When the kthreads finish processing
+ * these frames, they will aoedev_put the device.
+ */
struct aoedev *
aoedev_by_aoeaddr(int maj, int min)
{
@@ -28,13 +39,25 @@ aoedev_by_aoeaddr(int maj, int min)
spin_lock_irqsave(&devlist_lock, flags);

for (d=devlist; d; d=d->next)
- if (d->aoemajor == maj && d->aoeminor == min)
+ if (d->aoemajor == maj && d->aoeminor == min) {
+ d->ref++;
break;
+ }

spin_unlock_irqrestore(&devlist_lock, flags);
return d;
}

+void
+aoedev_put(struct aoedev *d)
+{
+ ulong flags;
+
+ spin_lock_irqsave(&devlist_lock, flags);
+ d->ref--;
+ spin_unlock_irqrestore(&devlist_lock, flags);
+}
+
static void
dummy_timer(ulong vp)
{
@@ -47,21 +70,26 @@ dummy_timer(ulong vp)
add_timer(&d->timer);
}

-void
-aoe_failbuf(struct aoedev *d, struct buf *buf)
+static void
+aoe_failip(struct aoedev *d)
{
+ struct request *rq;
struct bio *bio;
+ unsigned long n;
+
+ aoe_failbuf(d, d->ip.buf);

- if (buf == NULL)
+ rq = d->ip.rq;
+ if (rq == NULL)
return;
- buf->flags |= BUFFL_FAIL;
- if (buf->nframesout == 0) {
- if (buf == d->inprocess) /* ensure we only process this once */
- d->inprocess = NULL;
- bio = buf->bio;
- mempool_free(buf, d->bufpool);
- bio_endio(bio, -EIO);
+ while ((bio = d->ip.nxbio)) {
+ clear_bit(BIO_UPTODATE, &bio->bi_flags);
+ d->ip.nxbio = bio->bi_next;
+ n = (unsigned long) rq->special;
+ rq->special = (void *) --n;
}
+ if ((unsigned long) rq->special == 0)
+ aoe_end_request(d, rq, 0);
}

void
@@ -70,8 +98,11 @@ aoedev_downdev(struct aoedev *d)
struct aoetgt *t, **tt, **te;
struct frame *f;
struct list_head *head, *pos, *nx;
+ struct request *rq;
int i;

+ d->flags &= ~DEVFL_UP;
+
/* clean out active buffers on all targets */
tt = d->targets;
te = tt + NTARGETS;
@@ -92,22 +123,20 @@ aoedev_downdev(struct aoedev *d)
t->nout = 0;
}

- /* clean out the in-process buffer (if any) */
- aoe_failbuf(d, d->inprocess);
- d->inprocess = NULL;
+ /* clean out the in-process request (if any) */
+ aoe_failip(d);
d->htgt = NULL;

- /* clean out all pending I/O */
- while (!list_empty(&d->bufq)) {
- struct buf *buf = container_of(d->bufq.next, struct buf, bufs);
- list_del(d->bufq.next);
- aoe_failbuf(d, buf);
+ /* fast fail all pending I/O */
+ if (d->blkq) {
+ while ((rq = blk_peek_request(d->blkq))) {
+ blk_start_request(rq);
+ aoe_end_request(d, rq, 1);
+ }
}

if (d->gd)
set_capacity(d->gd, 0);
-
- d->flags &= ~DEVFL_UP;
}

static void
@@ -120,6 +149,7 @@ aoedev_freedev(struct aoedev *d)
aoedisk_rm_sysfs(d);
del_gendisk(d->gd);
put_disk(d->gd);
+ blk_cleanup_queue(d->blkq);
}
t = d->targets;
e = t + NTARGETS;
@@ -128,7 +158,6 @@ aoedev_freedev(struct aoedev *d)
if (d->bufpool)
mempool_destroy(d->bufpool);
skbpoolfree(d);
- blk_cleanup_queue(d->blkq);
kfree(d);
}

@@ -155,7 +184,8 @@ aoedev_flush(const char __user *str, size_t cnt)
spin_lock(&d->lock);
if ((!all && (d->flags & DEVFL_UP))
|| (d->flags & (DEVFL_GDALLOC|DEVFL_NEWSIZE))
- || d->nopen) {
+ || d->nopen
+ || d->ref) {
spin_unlock(&d->lock);
dd = &d->next;
continue;
@@ -176,12 +206,15 @@ aoedev_flush(const char __user *str, size_t cnt)
return 0;
}

-/* I'm not really sure that this is a realistic problem, but if the
-network driver goes gonzo let's just leak memory after complaining. */
+/* This has been confirmed to occur once with Tms=3*1000 due to the
+ * driver changing link and not processing its transmit ring. The
+ * problem is hard enough to solve by returning an error that I'm
+ * still punting on "solving" this.
+ */
static void
skbfree(struct sk_buff *skb)
{
- enum { Sms = 100, Tms = 3*1000};
+ enum { Sms = 250, Tms = 30 * 1000};
int i = Tms / Sms;

if (skb == NULL)
@@ -222,8 +255,10 @@ aoedev_by_sysminor_m(ulong sysminor)
spin_lock_irqsave(&devlist_lock, flags);

for (d=devlist; d; d=d->next)
- if (d->sysminor == sysminor)
+ if (d->sysminor == sysminor) {
+ d->ref++;
break;
+ }
if (d)
goto out;
d = kcalloc(1, sizeof *d, GFP_ATOMIC);
@@ -231,7 +266,6 @@ aoedev_by_sysminor_m(ulong sysminor)
goto out;
INIT_WORK(&d->work, aoecmd_sleepwork);
spin_lock_init(&d->lock);
- skb_queue_head_init(&d->sendq);
skb_queue_head_init(&d->skbpool);
init_timer(&d->timer);
d->timer.data = (ulong) d;
@@ -240,7 +274,7 @@ aoedev_by_sysminor_m(ulong sysminor)
add_timer(&d->timer);
d->bufpool = NULL; /* defer to aoeblk_gdalloc */
d->tgt = d->targets;
- INIT_LIST_HEAD(&d->bufq);
+ d->ref = 1;
d->sysminor = sysminor;
d->aoemajor = AOEMAJOR(sysminor);
d->aoeminor = AOEMINOR(sysminor);
@@ -274,6 +308,7 @@ aoedev_exit(void)
struct aoedev *d;
ulong flags;

+ aoe_flush_iocq();
while ((d = devlist)) {
devlist = d->next;

--
1.7.2.5


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