nfsd4: drc containerization

The nfsd duplicate reply cache should not be shared between network
namespaces.

The most straightforward way to fix this is just to move every global in
the code to per-net-namespace memory, so that's what we do.

Still todo: sort out which members of nfsd_stats should be global and
which per-net-namespace.

Signed-off-by: J. Bruce Fields <bfields@redhat.com>

fs/nfsd/cache.h

@@ -10,6 +10,7 @@
 #define NFSCACHE_H
 
 #include <linux/sunrpc/svc.h>
+#include "netns.h"
 
 /*
  * Representation of a reply cache entry.
@@ -77,8 +78,8 @@ enum {
 /* Checksum this amount of the request */
 #define RC_CSUMLEN		(256U)
 
-int	nfsd_reply_cache_init(void);
-void	nfsd_reply_cache_shutdown(void);
+int	nfsd_reply_cache_init(struct nfsd_net *);
+void	nfsd_reply_cache_shutdown(struct nfsd_net *);
 int	nfsd_cache_lookup(struct svc_rqst *);
 void	nfsd_cache_update(struct svc_rqst *, int, __be32 *);
 int	nfsd_reply_cache_stats_open(struct inode *, struct file *);

fs/nfsd/netns.h

@@ -127,6 +127,41 @@ struct nfsd_net {
 	 */
 	bool *nfsd_versions;
 	bool *nfsd4_minorversions;
+
+	/*
+	 * Duplicate reply cache
+	 */
+	struct nfsd_drc_bucket   *drc_hashtbl;
+	struct kmem_cache        *drc_slab;
+
+	/* max number of entries allowed in the cache */
+	unsigned int             max_drc_entries;
+
+	/* number of significant bits in the hash value */
+	unsigned int             maskbits;
+	unsigned int             drc_hashsize;
+
+	/*
+	 * Stats and other tracking of on the duplicate reply cache. All of these and
+	 * the "rc" fields in nfsdstats are protected by the cache_lock
+	 */
+
+	/* total number of entries */
+	atomic_t                 num_drc_entries;
+
+	/* cache misses due only to checksum comparison failures */
+	unsigned int             payload_misses;
+
+	/* amount of memory (in bytes) currently consumed by the DRC */
+	unsigned int             drc_mem_usage;
+
+	/* longest hash chain seen */
+	unsigned int             longest_chain;
+
+	/* size of cache when we saw the longest hash chain */
+	unsigned int             longest_chain_cachesize;
+
+	struct shrinker		nfsd_reply_cache_shrinker;
 };
 
 /* Simple check to find out if a given net was properly initialized */