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authorEd Cashin <ecashin@coraid.com>2012-10-04 17:16:23 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2012-10-06 03:05:25 +0900
commit69cf2d85de773d998798e47e3335b85e5645d157 (patch)
tree765eb2be45726e7e098fe73b7f368239c0461342 /drivers/block/aoe/aoecmd.c
parent896831f5909e2733c13c9cb13a1a215f10c3eaa8 (diff)
downloadop-kernel-dev-69cf2d85de773d998798e47e3335b85e5645d157.zip
op-kernel-dev-69cf2d85de773d998798e47e3335b85e5645d157.tar.gz
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> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'drivers/block/aoe/aoecmd.c')
-rw-r--r--drivers/block/aoe/aoecmd.c282
1 files changed, 203 insertions, 79 deletions
diff --git a/drivers/block/aoe/aoecmd.c b/drivers/block/aoe/aoecmd.c
index 59b333c..5928a08 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.");
@@ -283,17 +285,20 @@ 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)
@@ -312,7 +317,7 @@ 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++;
@@ -364,8 +369,11 @@ 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;
}
@@ -415,6 +423,7 @@ 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;
@@ -444,7 +453,9 @@ 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
@@ -554,7 +565,6 @@ 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;
@@ -603,6 +613,12 @@ 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;
@@ -641,45 +657,131 @@ 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
@@ -802,25 +904,6 @@ 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)
{
@@ -842,6 +925,43 @@ 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)
{
@@ -876,7 +996,7 @@ 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;
}
@@ -887,7 +1007,7 @@ 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);
@@ -927,18 +1047,13 @@ 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);
}
@@ -1061,12 +1176,14 @@ 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",
@@ -1185,8 +1302,10 @@ 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);
@@ -1223,10 +1342,8 @@ 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) {
@@ -1235,8 +1352,7 @@ 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) {
@@ -1257,18 +1373,14 @@ 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);
@@ -1297,8 +1409,19 @@ 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;
@@ -1324,6 +1447,7 @@ flush_iocq(void)
aoe_freetframe(f);
spin_unlock_irqrestore(&d->lock, flags);
dev_kfree_skb(skb);
+ aoedev_put(d);
}
}
@@ -1344,5 +1468,5 @@ void
aoecmd_exit(void)
{
aoe_ktstop(&kts);
- flush_iocq();
+ aoe_flush_iocq();
}
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