NFS: Add some new I/O counters for FS-Cache doing things for NFS

Add some new NFS I/O counters for FS-Cache doing things for NFS.  A new line is
emitted into /proc/pid/mountstats if caching is enabled that looks like:

	fsc: <rok> <rfl> <wok> <wfl> <unc>

Where <rok> is the number of pages read successfully from the cache, <rfl> is
the number of failed page reads against the cache, <wok> is the number of
successful page writes to the cache, <wfl> is the number of failed page writes
to the cache, and <unc> is the number of NFS pages that have been disconnected
from the cache.

Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Steve Dickson <steved@redhat.com>
Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Acked-by: Al Viro <viro@zeniv.linux.org.uk>
Tested-by: Daire Byrne <Daire.Byrne@framestore.com>

fs/nfs/iostat.h

@@ -16,6 +16,9 @@
 
 struct nfs_iostats {
 	unsigned long long	bytes[__NFSIOS_BYTESMAX];
+#ifdef CONFIG_NFS_FSCACHE
+	unsigned long long	fscache[__NFSIOS_FSCACHEMAX];
+#endif
 	unsigned long		events[__NFSIOS_COUNTSMAX];
 } ____cacheline_aligned;
 
@@ -57,6 +60,21 @@ static inline void nfs_add_stats(const struct inode *inode,
 	nfs_add_server_stats(NFS_SERVER(inode), stat, addend);
 }
 
+#ifdef CONFIG_NFS_FSCACHE
+static inline void nfs_add_fscache_stats(struct inode *inode,
+					 enum nfs_stat_fscachecounters stat,
+					 unsigned long addend)
+{
+	struct nfs_iostats *iostats;
+	int cpu;
+
+	cpu = get_cpu();
+	iostats = per_cpu_ptr(NFS_SERVER(inode)->io_stats, cpu);
+	iostats->fscache[stat] += addend;
+	put_cpu_no_resched();
+}
+#endif
+
 static inline struct nfs_iostats *nfs_alloc_iostats(void)
 {
 	return alloc_percpu(struct nfs_iostats);

fs/nfs/super.c

@@ -642,6 +642,10 @@ static int nfs_show_stats(struct seq_file *m, struct vfsmount *mnt)
 			totals.events[i] += stats->events[i];
 		for (i = 0; i < __NFSIOS_BYTESMAX; i++)
 			totals.bytes[i] += stats->bytes[i];
+#ifdef CONFIG_NFS_FSCACHE
+		for (i = 0; i < __NFSIOS_FSCACHEMAX; i++)
+			totals.fscache[i] += stats->fscache[i];
+#endif
 
 		preempt_enable();
 	}
@@ -652,6 +656,13 @@ static int nfs_show_stats(struct seq_file *m, struct vfsmount *mnt)
 	seq_printf(m, "\n\tbytes:\t");
 	for (i = 0; i < __NFSIOS_BYTESMAX; i++)
 		seq_printf(m, "%Lu ", totals.bytes[i]);
+#ifdef CONFIG_NFS_FSCACHE
+	if (nfss->options & NFS_OPTION_FSCACHE) {
+		seq_printf(m, "\n\tfsc:\t");
+		for (i = 0; i < __NFSIOS_FSCACHEMAX; i++)
+			seq_printf(m, "%Lu ", totals.bytes[i]);
+	}
+#endif
 	seq_printf(m, "\n");
 
 	rpc_print_iostats(m, nfss->client);

include/linux/nfs_iostat.h

@@ -116,4 +116,16 @@ enum nfs_stat_eventcounters {
 	__NFSIOS_COUNTSMAX,
 };
 
+/*
+ * NFS local caching servicing counters
+ */
+enum nfs_stat_fscachecounters {
+	NFSIOS_FSCACHE_PAGES_READ_OK,
+	NFSIOS_FSCACHE_PAGES_READ_FAIL,
+	NFSIOS_FSCACHE_PAGES_WRITTEN_OK,
+	NFSIOS_FSCACHE_PAGES_WRITTEN_FAIL,
+	NFSIOS_FSCACHE_PAGES_UNCACHED,
+	__NFSIOS_FSCACHEMAX,
+};
+
 #endif	/* _LINUX_NFS_IOSTAT */