From ae74136b4bb64440a55117e12065b8c282ab6c1a Mon Sep 17 00:00:00 2001 From: Trond Myklebust Date: Wed, 3 Oct 2018 12:01:22 -0400 Subject: SUNRPC: Allow cache lookups to use RCU protection rather than the r/w spinlock Instead of the reader/writer spinlock, allow cache lookups to use RCU for looking up entries. This is more efficient since modifications can occur while other entries are being looked up. Note that for now, we keep the reader/writer spinlock until all users have been converted to use RCU-safe freeing of their cache entries. Signed-off-by: Trond Myklebust Signed-off-by: J. Bruce Fields --- include/linux/sunrpc/cache.h | 12 ++++++++++++ 1 file changed, 12 insertions(+) (limited to 'include/linux/sunrpc/cache.h') diff --git a/include/linux/sunrpc/cache.h b/include/linux/sunrpc/cache.h index 40d2822f0e2f..cf3e17ee2786 100644 --- a/include/linux/sunrpc/cache.h +++ b/include/linux/sunrpc/cache.h @@ -167,6 +167,9 @@ extern const struct file_operations cache_file_operations_pipefs; extern const struct file_operations content_file_operations_pipefs; extern const struct file_operations cache_flush_operations_pipefs; +extern struct cache_head * +sunrpc_cache_lookup_rcu(struct cache_detail *detail, + struct cache_head *key, int hash); extern struct cache_head * sunrpc_cache_lookup(struct cache_detail *detail, struct cache_head *key, int hash); @@ -186,6 +189,12 @@ static inline struct cache_head *cache_get(struct cache_head *h) return h; } +static inline struct cache_head *cache_get_rcu(struct cache_head *h) +{ + if (kref_get_unless_zero(&h->ref)) + return h; + return NULL; +} static inline void cache_put(struct cache_head *h, struct cache_detail *cd) { @@ -227,6 +236,9 @@ extern void sunrpc_cache_unhash(struct cache_detail *, struct cache_head *); extern void *cache_seq_start(struct seq_file *file, loff_t *pos); extern void *cache_seq_next(struct seq_file *file, void *p, loff_t *pos); extern void cache_seq_stop(struct seq_file *file, void *p); +extern void *cache_seq_start_rcu(struct seq_file *file, loff_t *pos); +extern void *cache_seq_next_rcu(struct seq_file *file, void *p, loff_t *pos); +extern void cache_seq_stop_rcu(struct seq_file *file, void *p); extern void qword_add(char **bpp, int *lp, char *str); extern void qword_addhex(char **bpp, int *lp, char *buf, int blen); -- cgit v1.2.3 From d48cf356a13073853f19be6ca5ebbecfc2762ebe Mon Sep 17 00:00:00 2001 From: Trond Myklebust Date: Mon, 1 Oct 2018 10:41:51 -0400 Subject: SUNRPC: Remove non-RCU protected lookup Clean up the cache code by removing the non-RCU protected lookup. Signed-off-by: Trond Myklebust Signed-off-by: J. Bruce Fields --- include/linux/sunrpc/cache.h | 6 ------ 1 file changed, 6 deletions(-) (limited to 'include/linux/sunrpc/cache.h') diff --git a/include/linux/sunrpc/cache.h b/include/linux/sunrpc/cache.h index cf3e17ee2786..c3d67e893430 100644 --- a/include/linux/sunrpc/cache.h +++ b/include/linux/sunrpc/cache.h @@ -171,9 +171,6 @@ extern struct cache_head * sunrpc_cache_lookup_rcu(struct cache_detail *detail, struct cache_head *key, int hash); extern struct cache_head * -sunrpc_cache_lookup(struct cache_detail *detail, - struct cache_head *key, int hash); -extern struct cache_head * sunrpc_cache_update(struct cache_detail *detail, struct cache_head *new, struct cache_head *old, int hash); @@ -233,9 +230,6 @@ extern void sunrpc_cache_unregister_pipefs(struct cache_detail *); extern void sunrpc_cache_unhash(struct cache_detail *, struct cache_head *); /* Must store cache_detail in seq_file->private if using next three functions */ -extern void *cache_seq_start(struct seq_file *file, loff_t *pos); -extern void *cache_seq_next(struct seq_file *file, void *p, loff_t *pos); -extern void cache_seq_stop(struct seq_file *file, void *p); extern void *cache_seq_start_rcu(struct seq_file *file, loff_t *pos); extern void *cache_seq_next_rcu(struct seq_file *file, void *p, loff_t *pos); extern void cache_seq_stop_rcu(struct seq_file *file, void *p); -- cgit v1.2.3 From 1863d77f15da0addcd293a1719fa5d3ef8cde3ca Mon Sep 17 00:00:00 2001 From: Trond Myklebust Date: Mon, 1 Oct 2018 10:41:52 -0400 Subject: SUNRPC: Replace the cache_detail->hash_lock with a regular spinlock Now that the reader functions are all RCU protected, use a regular spinlock rather than a reader/writer lock. Signed-off-by: Trond Myklebust Signed-off-by: J. Bruce Fields --- include/linux/sunrpc/cache.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'include/linux/sunrpc/cache.h') diff --git a/include/linux/sunrpc/cache.h b/include/linux/sunrpc/cache.h index c3d67e893430..5a3e95017fc6 100644 --- a/include/linux/sunrpc/cache.h +++ b/include/linux/sunrpc/cache.h @@ -67,7 +67,7 @@ struct cache_detail { struct module * owner; int hash_size; struct hlist_head * hash_table; - rwlock_t hash_lock; + spinlock_t hash_lock; char *name; void (*cache_put)(struct kref *); -- cgit v1.2.3