NFSD: Record number of flush calls

Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

fs/nfsd/filecache.c

@@ -46,6 +46,7 @@ static DEFINE_PER_CPU(unsigned long, nfsd_file_cache_hits);
 static DEFINE_PER_CPU(unsigned long, nfsd_file_acquisitions);
 static DEFINE_PER_CPU(unsigned long, nfsd_file_releases);
 static DEFINE_PER_CPU(unsigned long, nfsd_file_total_age);
+static DEFINE_PER_CPU(unsigned long, nfsd_file_pages_flushed);
 static DEFINE_PER_CPU(unsigned long, nfsd_file_evictions);
 
 struct nfsd_fcache_disposal {
@@ -243,7 +244,12 @@ nfsd_file_check_write_error(struct nfsd_file *nf)
 static void
 nfsd_file_flush(struct nfsd_file *nf)
 {
-	if (nf->nf_file && vfs_fsync(nf->nf_file, 1) != 0)
+	struct file *file = nf->nf_file;
+
+	if (!file || !(file->f_mode & FMODE_WRITE))
+		return;
+	this_cpu_add(nfsd_file_pages_flushed, file->f_mapping->nrpages);
+	if (vfs_fsync(file, 1) != 0)
 		nfsd_reset_write_verifier(net_generic(nf->nf_net, nfsd_net_id));
 }
 
@@ -1070,7 +1076,8 @@ nfsd_file_create(struct svc_rqst *rqstp, struct svc_fh *fhp,
  */
 static int nfsd_file_cache_stats_show(struct seq_file *m, void *v)
 {
-	unsigned long hits = 0, acquisitions = 0, releases = 0, evictions = 0;
+	unsigned long releases = 0, pages_flushed = 0, evictions = 0;
+	unsigned long hits = 0, acquisitions = 0;
 	unsigned int i, count = 0, longest = 0;
 	unsigned long lru = 0, total_age = 0;
 
@@ -1095,6 +1102,7 @@ static int nfsd_file_cache_stats_show(struct seq_file *m, void *v)
 		releases += per_cpu(nfsd_file_releases, i);
 		total_age += per_cpu(nfsd_file_total_age, i);
 		evictions += per_cpu(nfsd_file_evictions, i);
+		pages_flushed += per_cpu(nfsd_file_pages_flushed, i);
 	}
 
 	seq_printf(m, "total entries: %u\n", count);
@@ -1108,6 +1116,7 @@ static int nfsd_file_cache_stats_show(struct seq_file *m, void *v)
 		seq_printf(m, "mean age (ms): %ld\n", total_age / releases);
 	else
 		seq_printf(m, "mean age (ms): -\n");
+	seq_printf(m, "pages flushed: %lu\n", pages_flushed);
 	return 0;
 }