aoe: kernel thread handles I/O completions for simple locking

Make the frames the aoe driver uses to track the relationship between bios
and packets more flexible and detached, so that they can be passed to an
"aoe_ktio" thread for completion of I/O.

The frames are handled much like skbs, with a capped amount of
preallocation so that real-world use cases are likely to run smoothly and
degenerate gracefully even under memory pressure.

Decoupling I/O completion from the receive path and serializing it in a
process makes it easier to think about the correctness of the locking in
the driver, especially in the case of a remote MAC address becoming
unusable.

[dan.carpenter@oracle.com: cleanup an allocation a bit]
Signed-off-by: Ed Cashin <ecashin@coraid.com>
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 50 insertions, 34 deletions

diff --git a/drivers/block/aoe/aoedev.c b/drivers/block/aoe/aoedev.c
index b2d1fd3..40bae1a 100644
--- a/drivers/block/aoe/aoedev.c
+++ b/drivers/block/aoe/aoedev.c
@@ -48,47 +48,60 @@ dummy_timer(ulong vp)
 }
 
 void
-aoedev_downdev(struct aoedev *d)
+aoe_failbuf(struct aoedev *d, struct buf *buf)
 {
-	struct aoetgt **t, **te;
-	struct frame *f, *e;
-	struct buf *buf;
 	struct bio *bio;
 
-	t = d->targets;
-	te = t + NTARGETS;
-	for (; t < te && *t; t++) {
-		f = (*t)->frames;
-		e = f + (*t)->nframes;
-		for (; f < e; f->tag = FREETAG, f->buf = NULL, f++) {
-			if (f->tag == FREETAG || f->buf == NULL)
-				continue;
-			buf = f->buf;
-			bio = buf->bio;
-			if (--buf->nframesout == 0
-			&& buf != d->inprocess) {
-				mempool_free(buf, d->bufpool);
-				bio_endio(bio, -EIO);
-			}
-		}
-		(*t)->maxout = (*t)->nframes;
-		(*t)->nout = 0;
-	}
-	buf = d->inprocess;
-	if (buf) {
+	if (buf == 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);
 	}
+}
+
+void
+aoedev_downdev(struct aoedev *d)
+{
+	struct aoetgt *t, **tt, **te;
+	struct frame *f;
+	struct list_head *head, *pos, *nx;
+	int i;
+
+	/* clean out active buffers on all targets */
+	tt = d->targets;
+	te = tt + NTARGETS;
+	for (; tt < te && (t = *tt); tt++) {
+		for (i = 0; i < NFACTIVE; i++) {
+			head = &t->factive[i];
+			list_for_each_safe(pos, nx, head) {
+				list_del(pos);
+				f = list_entry(pos, struct frame, head);
+				if (f->buf) {
+					f->buf->nframesout--;
+					aoe_failbuf(d, f->buf);
+				}
+				aoe_freetframe(f);
+			}
+		}
+		t->maxout = t->nframes;
+		t->nout = 0;
+	}
+
+	/* clean out the in-process buffer (if any) */
+	aoe_failbuf(d, d->inprocess);
 	d->inprocess = NULL;
 	d->htgt = NULL;
 
+	/* clean out all pending I/O */
 	while (!list_empty(&d->bufq)) {
-		buf = container_of(d->bufq.next, struct buf, bufs);
+		struct buf *buf = container_of(d->bufq.next, struct buf, bufs);
 		list_del(d->bufq.next);
-		bio = buf->bio;
-		mempool_free(buf, d->bufpool);
-		bio_endio(bio, -EIO);
+		aoe_failbuf(d, buf);
 	}
 
 	if (d->gd)
@@ -242,13 +255,16 @@ aoedev_by_sysminor_m(ulong sysminor)
 static void
 freetgt(struct aoedev *d, struct aoetgt *t)
 {
-	struct frame *f, *e;
+	struct frame *f;
+	struct list_head *pos, *nx, *head;
 
-	f = t->frames;
-	e = f + t->nframes;
-	for (; f < e; f++)
+	head = &t->ffree;
+	list_for_each_safe(pos, nx, head) {
+		list_del(pos);
+		f = list_entry(pos, struct frame, head);
 		skbfree(f->skb);
-	kfree(t->frames);
+		kfree(f);
+	}
 	kfree(t);
 }