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authorJens Axboe <jens.axboe@oracle.com>2009-04-23 12:14:56 +0200
committerJens Axboe <jens.axboe@oracle.com>2009-04-24 08:54:22 +0200
commit3ac6c9f8a66726745136e46f63600550c3eb6cec (patch)
tree93d3217dc15a8183c8e6b29b36862caef01546d7 /block
parent26a2ac009c2b07e1959c8864ca23486c1c485587 (diff)
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cfq-iosched: fix bug with aliased request and cooperation detection
cfq_prio_tree_lookup() should return the direct match, yet it always returns zero. Fix that. cfq_prio_tree_add() assumes that we don't get a direct match, while it is very possible that we do. Using O_DIRECT, you can have different cfqq with matching requests, since you don't have the page cache to serialize things for you. Fix this bug by only adding the cfqq if there isn't an existing match. Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
Diffstat (limited to 'block')
-rw-r--r--block/cfq-iosched.c11
1 files changed, 6 insertions, 5 deletions
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index 20a54b8e03e..b0b754a6882 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -584,12 +584,13 @@ cfq_prio_tree_lookup(struct cfq_data *cfqd, int ioprio, sector_t sector,
else
break;
p = n;
+ cfqq = NULL;
}
*ret_parent = parent;
if (rb_link)
*rb_link = p;
- return NULL;
+ return cfqq;
}
static void cfq_prio_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq)
@@ -608,10 +609,10 @@ static void cfq_prio_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq)
__cfqq = cfq_prio_tree_lookup(cfqd, cfqq->ioprio, cfqq->next_rq->sector,
&parent, &p);
- BUG_ON(__cfqq);
-
- rb_link_node(&cfqq->p_node, parent, p);
- rb_insert_color(&cfqq->p_node, root);
+ if (!__cfqq) {
+ rb_link_node(&cfqq->p_node, parent, p);
+ rb_insert_color(&cfqq->p_node, root);
+ }
}
/*