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[PATCH 2/2] cfq: fix cic's rbtree traversal

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When queue dies, we set cic->key=NULL as dead mark. So, when we
traverse a rbtree, we must check whether it's still valid key. if it
was invalidated, drop it, then restart the traversal from top.

Signed-off-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
Signed-off-by: Jens Axboe <axboe@suse.de>
This commit is contained in:
OGAWA Hirofumi 2006-04-18 09:45:18 +02:00 committed by Jens Axboe
parent fba822722e
commit dbecf3ab40
1 changed files with 27 additions and 6 deletions
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33
block/cfq-iosched.c
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@ -1472,15 +1472,31 @@ out:
return cfqq;
}
static void
cfq_drop_dead_cic(struct io_context *ioc, struct cfq_io_context *cic)
{
read_lock(&cfq_exit_lock);
rb_erase(&cic->rb_node, &ioc->cic_root);
read_unlock(&cfq_exit_lock);
kmem_cache_free(cfq_ioc_pool, cic);
atomic_dec(&ioc_count);
}
static struct cfq_io_context *
cfq_cic_rb_lookup(struct cfq_data *cfqd, struct io_context *ioc)
{
struct rb_node *n = ioc->cic_root.rb_node;
struct rb_node *n;
struct cfq_io_context *cic;
void *key = cfqd;
restart:
n = ioc->cic_root.rb_node;
while (n) {
cic = rb_entry(n, struct cfq_io_context, rb_node);
if (unlikely(!cic->key)) {
cfq_drop_dead_cic(ioc, cic);
goto restart;
}
if (key < cic->key)
n = n->rb_left;
@ -1497,20 +1513,24 @@ static inline void
cfq_cic_link(struct cfq_data *cfqd, struct io_context *ioc,
struct cfq_io_context *cic)
{
struct rb_node **p = &ioc->cic_root.rb_node;
struct rb_node *parent = NULL;
struct rb_node **p;
struct rb_node *parent;
struct cfq_io_context *__cic;
read_lock(&cfq_exit_lock);
cic->ioc = ioc;
cic->key = cfqd;
ioc->set_ioprio = cfq_ioc_set_ioprio;
restart:
parent = NULL;
p = &ioc->cic_root.rb_node;
while (*p) {
parent = *p;
__cic = rb_entry(parent, struct cfq_io_context, rb_node);
if (unlikely(!__cic->key)) {
cfq_drop_dead_cic(ioc, cic);
goto restart;
}
if (cic->key < __cic->key)
p = &(*p)->rb_left;
@ -1520,6 +1540,7 @@ cfq_cic_link(struct cfq_data *cfqd, struct io_context *ioc,
BUG();
}
read_lock(&cfq_exit_lock);
rb_link_node(&cic->rb_node, parent, p);
rb_insert_color(&cic->rb_node, &ioc->cic_root);
list_add(&cic->queue_list, &cfqd->cic_list);