From: Kent Overstreet <kmo@daterainc.com>
Date: Sat, 10 Aug 2013 04:14:13 +0000 (-0700)
Subject: bcache: Don't touch bucket gen for dirty ptrs
X-Git-Tag: next-20140109~46^2~1^2~29
X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=d56d000a1f424aa77538bd5aad18b43037ed20cc;p=karo-tx-linux.git

bcache: Don't touch bucket gen for dirty ptrs

Unnecessary since a bucket that has dirty pointers pointing to it can
never be invalidated - and skipping it is a measurable performance
boost, since the bucket gen will usually be a cache miss.

Signed-off-by: Kent Overstreet <kmo@daterainc.com>
---

diff --git a/drivers/md/bcache/bset.c b/drivers/md/bcache/bset.c
index 16958704af3b..e51a739f7514 100644
--- a/drivers/md/bcache/bset.c
+++ b/drivers/md/bcache/bset.c
@@ -176,10 +176,14 @@ bool bch_ptr_bad(struct btree *b, const struct bkey *k)
 	    bch_ptr_invalid(b, k))
 		return true;
 
-	for (i = 0; i < KEY_PTRS(k); i++) {
+	for (i = 0; i < KEY_PTRS(k); i++)
 		if (!ptr_available(b->c, k, i))
 			return true;
 
+	if (!expensive_debug_checks(b->c) && KEY_DIRTY(k))
+		return false;
+
+	for (i = 0; i < KEY_PTRS(k); i++) {
 		g = PTR_BUCKET(b->c, k, i);
 		stale = ptr_stale(b->c, k, i);
 
diff --git a/drivers/md/bcache/request.c b/drivers/md/bcache/request.c
index 5878cdb39529..59b3d6df100b 100644
--- a/drivers/md/bcache/request.c
+++ b/drivers/md/bcache/request.c
@@ -630,7 +630,8 @@ static void bch_cache_read_endio(struct bio *bio, int error)
 
 	if (error)
 		s->iop.error = error;
-	else if (ptr_stale(s->iop.c, &b->key, 0)) {
+	else if (!KEY_DIRTY(&b->key) &&
+		 ptr_stale(s->iop.c, &b->key, 0)) {
 		atomic_long_inc(&s->iop.c->cache_read_races);
 		s->iop.error = -EINTR;
 	}