Add some tracepoints into the cachefiles write paths.

Signed-off-by: David Howells <dhowells@redhat.com>
cc: netfs@lists.linux.dev
---
 fs/cachefiles/io.c           | 4 ++++
 include/trace/events/netfs.h | 3 +++
 2 files changed, 7 insertions(+)

diff --git a/fs/cachefiles/io.c b/fs/cachefiles/io.c
index 6a821a959b59..92058ae43488 100644
--- a/fs/cachefiles/io.c
+++ b/fs/cachefiles/io.c
@@ -13,6 +13,7 @@
 #include <linux/falloc.h>
 #include <linux/sched/mm.h>
 #include <trace/events/fscache.h>
+#include <trace/events/netfs.h>
 #include "internal.h"
 
 struct cachefiles_kiocb {
@@ -366,6 +367,7 @@ static int cachefiles_write(struct netfs_cache_resources *cres,
 	if (!fscache_wait_for_operation(cres, FSCACHE_WANT_WRITE)) {
 		if (term_func)
 			term_func(term_func_priv, -ENOBUFS, false);
+		trace_netfs_sreq(term_func_priv, netfs_sreq_trace_cache_nowrite);
 		return -ENOBUFS;
 	}
 
@@ -695,6 +697,7 @@ static void cachefiles_issue_write(struct netfs_io_subrequest *subreq)
 		iov_iter_truncate(&subreq->io_iter, len);
 	}
 
+	trace_netfs_sreq(subreq, netfs_sreq_trace_cache_prepare);
 	cachefiles_begin_secure(cache, &saved_cred);
 	ret = __cachefiles_prepare_write(object, cachefiles_cres_file(cres),
 					 &start, &len, len, true);
@@ -704,6 +707,7 @@ static void cachefiles_issue_write(struct netfs_io_subrequest *subreq)
 		return;
 	}
 
+	trace_netfs_sreq(subreq, netfs_sreq_trace_cache_write);
 	cachefiles_write(&subreq->rreq->cache_resources,
 			 subreq->start, &subreq->io_iter,
 			 netfs_write_subrequest_terminated, subreq);
diff --git a/include/trace/events/netfs.h b/include/trace/events/netfs.h
index a0f5b13aab86..7c3c866ae183 100644
--- a/include/trace/events/netfs.h
+++ b/include/trace/events/netfs.h
@@ -74,6 +74,9 @@
 #define netfs_sreq_traces					\
 	EM(netfs_sreq_trace_add_donations,	"+DON ")	\
 	EM(netfs_sreq_trace_added,		"ADD  ")	\
+	EM(netfs_sreq_trace_cache_nowrite,	"CA-NW")	\
+	EM(netfs_sreq_trace_cache_prepare,	"CA-PR")	\
+	EM(netfs_sreq_trace_cache_write,	"CA-WR")	\
 	EM(netfs_sreq_trace_clear,		"CLEAR")	\
 	EM(netfs_sreq_trace_discard,		"DSCRD")	\
 	EM(netfs_sreq_trace_donate_to_prev,	"DON-P")	\