Patch "NFSD: Record number of flush calls" has been added to the 5.15-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    NFSD: Record number of flush calls

to the 5.15-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     nfsd-record-number-of-flush-calls.patch
and it can be found in the queue-5.15 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit ed9df63a717b90304234b1430e45d936c3c906b1
Author: Chuck Lever <chuck.lever@xxxxxxxxxx>
Date:   Fri Jul 8 14:24:45 2022 -0400

    NFSD: Record number of flush calls
    
    [ Upstream commit df2aff524faceaf743b7c5ab0f4fb86cb511f782 ]
    
    Reviewed-by: Jeff Layton <jlayton@xxxxxxxxxx>
    Signed-off-by: Chuck Lever <chuck.lever@xxxxxxxxxx>

diff --git a/fs/nfsd/filecache.c b/fs/nfsd/filecache.c
index e5bd9f06492c8..b9941d4ef20d6 100644
--- a/fs/nfsd/filecache.c
+++ b/fs/nfsd/filecache.c
@@ -45,6 +45,7 @@ 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 {
@@ -242,7 +243,12 @@ 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));
 }
 
@@ -1069,7 +1075,8 @@ 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;
 
@@ -1094,6 +1101,7 @@ 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);
@@ -1107,6 +1115,7 @@ 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;
 }