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Subject: [PATCH 22/64] fscache: Provide read/write stat counters for the cache
From:   David Howells <dhowells@redhat.com>
To:     linux-cachefs@redhat.com
Cc:     dhowells@redhat.com, Trond Myklebust <trondmy@hammerspace.com>,
        Anna Schumaker <anna.schumaker@netapp.com>,
        Steve French <sfrench@samba.org>,
        Dominique Martinet <asmadeus@codewreck.org>,
        Jeff Layton <jlayton@kernel.org>,
        Matthew Wilcox <willy@infradead.org>,
        Alexander Viro <viro@zeniv.linux.org.uk>,
        Omar Sandoval <osandov@osandov.com>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        linux-afs@lists.infradead.org, linux-nfs@vger.kernel.org,
        linux-cifs@vger.kernel.org, ceph-devel@vger.kernel.org,
        v9fs-developer@lists.sourceforge.net,
        linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org
Date:   Mon, 29 Nov 2021 14:28:15 +0000
Message-ID: <163819609532.215744.10821082637727410554.stgit@warthog.procyon.org.uk>
In-Reply-To: <163819575444.215744.318477214576928110.stgit@warthog.procyon.org.uk>
References: <163819575444.215744.318477214576928110.stgit@warthog.procyon.org.uk>
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Provide read/write stat counters for the cache backend to use.

Signed-off-by: David Howells <dhowells@redhat.com>
cc: linux-cachefs@redhat.com
---

 fs/fscache/stats.c            |    9 +++++++++
 include/linux/fscache-cache.h |   10 ++++++++++
 2 files changed, 19 insertions(+)

diff --git a/fs/fscache/stats.c b/fs/fscache/stats.c
index cdbb672a274f..db42beb1ba3f 100644
--- a/fs/fscache/stats.c
+++ b/fs/fscache/stats.c
@@ -35,6 +35,11 @@ atomic_t fscache_n_relinquishes;
 atomic_t fscache_n_relinquishes_retire;
 atomic_t fscache_n_relinquishes_dropped;
 
+atomic_t fscache_n_read;
+EXPORT_SYMBOL(fscache_n_read);
+atomic_t fscache_n_write;
+EXPORT_SYMBOL(fscache_n_write);
+
 /*
  * display the general statistics
  */
@@ -72,6 +77,10 @@ int fscache_stats_show(struct seq_file *m, void *v)
 		   atomic_read(&fscache_n_relinquishes_retire),
 		   atomic_read(&fscache_n_relinquishes_dropped));
 
+	seq_printf(m, "IO     : rd=%u wr=%u\n",
+		   atomic_read(&fscache_n_read),
+		   atomic_read(&fscache_n_write));
+
 	netfs_stats_show(m);
 	return 0;
 }
diff --git a/include/linux/fscache-cache.h b/include/linux/fscache-cache.h
index 5525df056877..1398b71539ae 100644
--- a/include/linux/fscache-cache.h
+++ b/include/linux/fscache-cache.h
@@ -179,4 +179,14 @@ static inline void fscache_wait_for_objects(struct fscache_cache *cache)
 		   atomic_read(&cache->object_count) == 0);
 }
 
+#ifdef CONFIG_FSCACHE_STATS
+extern atomic_t fscache_n_read;
+extern atomic_t fscache_n_write;
+#define fscache_count_read() atomic_inc(&fscache_n_read)
+#define fscache_count_write() atomic_inc(&fscache_n_write)
+#else
+#define fscache_count_read() do {} while(0)
+#define fscache_count_write() do {} while(0)
+#endif
+
 #endif /* _LINUX_FSCACHE_CACHE_H */