Merge tag 'nfsd-4.20' of git://linux-nfs.org/~bfields/linux

Pull nfsd updates from Bruce Fields:
 "Olga added support for the NFSv4.2 asynchronous copy protocol. We
  already supported COPY, by copying a limited amount of data and then
  returning a short result, letting the client resend. The asynchronous
  protocol should offer better performance at the expense of some
  complexity.

  The other highlight is Trond's work to convert the duplicate reply
  cache to a red-black tree, and to move it and some other server caches
  to RCU. (Previously these have meant taking global spinlocks on every
  RPC)

  Otherwise, some RDMA work and miscellaneous bugfixes"

* tag 'nfsd-4.20' of git://linux-nfs.org/~bfields/linux: (30 commits)
  lockd: fix access beyond unterminated strings in prints
  nfsd: Fix an Oops in free_session()
  nfsd: correctly decrement odstate refcount in error path
  svcrdma: Increase the default connection credit limit
  svcrdma: Remove try_module_get from backchannel
  svcrdma: Remove ->release_rqst call in bc reply handler
  svcrdma: Reduce max_send_sges
  nfsd: fix fall-through annotations
  knfsd: Improve lookup performance in the duplicate reply cache using an rbtree
  knfsd: Further simplify the cache lookup
  knfsd: Simplify NFS duplicate replay cache
  knfsd: Remove dead code from nfsd_cache_lookup
  SUNRPC: Simplify TCP receive code
  SUNRPC: Replace the cache_detail->hash_lock with a regular spinlock
  SUNRPC: Remove non-RCU protected lookup
  NFS: Fix up a typo in nfs_dns_ent_put
  NFS: Lockless DNS lookups
  knfsd: Lockless lookup of NFSv4 identities.
  SUNRPC: Lockless server RPCSEC_GSS context lookup
  knfsd: Allow lockless lookups of the exports
  ...

1 files changed, 12 insertions, 6 deletions

diff --git a/include/linux/sunrpc/cache.h b/include/linux/sunrpc/cache.h
index 40d2822f0e2f..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 *);
@@ -168,8 +168,8 @@ 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(struct cache_detail *detail,
-		    struct cache_head *key, int hash);
+sunrpc_cache_lookup_rcu(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);
@@ -186,6 +186,12 @@ 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)
 {
@@ -224,9 +230,9 @@ 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);
 
 extern void qword_add(char **bpp, int *lp, char *str);
 extern void qword_addhex(char **bpp, int *lp, char *buf, int blen);