Use an rbtree to ensure the lookup/insert of an entry in a DRC bucket is
O(log(N)).
Signed-off-by: Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx>
---
fs/nfsd/cache.h | 1 +
fs/nfsd/nfscache.c | 37 ++++++++++++++++++++++++++-----------
2 files changed, 27 insertions(+), 11 deletions(-)
diff --git a/fs/nfsd/cache.h b/fs/nfsd/cache.h
index cbcdc15753b7..ef1c8aa89ca4 100644
--- a/fs/nfsd/cache.h
+++ b/fs/nfsd/cache.h
@@ -29,6 +29,7 @@ struct svc_cacherep {
struct sockaddr_in6 k_addr;
} c_key;
+ struct rb_node c_node;
struct list_head c_lru;
unsigned char c_state, /* unused, inprog, done */
c_type, /* status, buffer */
diff --git a/fs/nfsd/nfscache.c b/fs/nfsd/nfscache.c
index 230cc83921ad..e2fe0e9ce0df 100644
--- a/fs/nfsd/nfscache.c
+++ b/fs/nfsd/nfscache.c
@@ -30,6 +30,7 @@
#define TARGET_BUCKET_SIZE 64
struct nfsd_drc_bucket {
+ struct rb_root rb_head;
struct list_head lru_head;
spinlock_t cache_lock;
};
@@ -129,6 +130,7 @@ nfsd_reply_cache_alloc(struct svc_rqst *rqstp, __wsum csum)
if (rp) {
rp->c_state = RC_UNUSED;
rp->c_type = RC_NOCACHE;
+ RB_CLEAR_NODE(&rp->c_node);
INIT_LIST_HEAD(&rp->c_lru);
memset(&rp->c_key, 0, sizeof(rp->c_key));
@@ -145,13 +147,14 @@ nfsd_reply_cache_alloc(struct svc_rqst *rqstp, __wsum csum)
}
static void
-nfsd_reply_cache_free_locked(struct svc_cacherep *rp)
+nfsd_reply_cache_free_locked(struct nfsd_drc_bucket *b, struct svc_cacherep *rp)
{
if (rp->c_type == RC_REPLBUFF && rp->c_replvec.iov_base) {
drc_mem_usage -= rp->c_replvec.iov_len;
kfree(rp->c_replvec.iov_base);
}
if (rp->c_state != RC_UNUSED) {
+ rb_erase(&rp->c_node, &b->rb_head);
list_del(&rp->c_lru);
atomic_dec(&num_drc_entries);
drc_mem_usage -= sizeof(*rp);
@@ -163,7 +166,7 @@ static void
nfsd_reply_cache_free(struct nfsd_drc_bucket *b, struct svc_cacherep *rp)
{
spin_lock(&b->cache_lock);
- nfsd_reply_cache_free_locked(rp);
+ nfsd_reply_cache_free_locked(b, rp);
spin_unlock(&b->cache_lock);
}
@@ -219,7 +222,7 @@ void nfsd_reply_cache_shutdown(void)
struct list_head *head = &drc_hashtbl[i].lru_head;
while (!list_empty(head)) {
rp = list_first_entry(head, struct svc_cacherep, c_lru);
- nfsd_reply_cache_free_locked(rp);
+ nfsd_reply_cache_free_locked(&drc_hashtbl[i], rp);
}
}
@@ -258,7 +261,7 @@ prune_bucket(struct nfsd_drc_bucket *b)
if (atomic_read(&num_drc_entries) <= max_drc_entries &&
time_before(jiffies, rp->c_timestamp + RC_EXPIRE))
break;
- nfsd_reply_cache_free_locked(rp);
+ nfsd_reply_cache_free_locked(b, rp);
freed++;
}
return freed;
@@ -349,17 +352,29 @@ static struct svc_cacherep *
nfsd_cache_insert(struct nfsd_drc_bucket *b, struct svc_cacherep *key)
{
struct svc_cacherep *rp, *ret = key;
- struct list_head *rh = &b->lru_head;
+ struct rb_node **p = &b->rb_head.rb_node,
+ *parent = NULL;
unsigned int entries = 0;
+ int cmp;
- list_for_each_entry(rp, rh, c_lru) {
+ while (*p != NULL) {
++entries;
- if (nfsd_cache_key_cmp(key, rp) == 0) {
+ parent = *p;
+ rp = rb_entry(parent, struct svc_cacherep, c_node);
+
+ cmp = nfsd_cache_key_cmp(key, rp);
+ if (cmp < 0)
+ p = &parent->rb_left;
+ else if (cmp > 0)
+ p = &parent->rb_right;
+ else {
ret = rp;
- break;
+ goto out;
}
}
-
+ rb_link_node(&key->c_node, parent, p);
+ rb_insert_color(&key->c_node, &b->rb_head);
+out:
/* tally hash chain length stats */
if (entries > longest_chain) {
longest_chain = entries;
@@ -414,7 +429,7 @@ nfsd_cache_lookup(struct svc_rqst *rqstp)
spin_lock(&b->cache_lock);
found = nfsd_cache_insert(b, rp);
if (found != rp) {
- nfsd_reply_cache_free_locked(rp);
+ nfsd_reply_cache_free_locked(NULL, rp);
rp = found;
goto found_entry;
}
@@ -462,7 +477,7 @@ nfsd_cache_lookup(struct svc_rqst *rqstp)
break;
default:
printk(KERN_WARNING "nfsd: bad repcache type %d\n", rp->c_type);
- nfsd_reply_cache_free_locked(rp);
+ nfsd_reply_cache_free_locked(b, rp);
}
goto out;
--
2.17.1
