netfs: Add tracepoints

Add three tracepoints to track the activity of the read helpers:

 (1) netfs/netfs_read

     This logs entry to the read helpers and also expansion of the range in
     a readahead request.

 (2) netfs/netfs_rreq

     This logs the progress of netfs_read_request objects which track
     read requests.  A read request may be a compound of multiple
     subrequests.

 (3) netfs/netfs_sreq

     This logs the progress of netfs_read_subrequest objects, which track
     the contributions from various sources to a read request.

Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-and-tested-by: Jeff Layton <jlayton@kernel.org>
Tested-by: Dave Wysochanski <dwysocha@redhat.com>
Tested-By: Marc Dionne <marc.dionne@auristor.com>
cc: Matthew Wilcox <willy@infradead.org>
cc: linux-mm@kvack.org
cc: linux-cachefs@redhat.com
cc: linux-afs@lists.infradead.org
cc: linux-nfs@vger.kernel.org
cc: linux-cifs@vger.kernel.org
cc: ceph-devel@vger.kernel.org
cc: v9fs-developer@lists.sourceforge.net
cc: linux-fsdevel@vger.kernel.org
Link: https://lore.kernel.org/r/161118138060.1232039.5353374588021776217.stgit@warthog.procyon.org.uk/ # rfc
Link: https://lore.kernel.org/r/161161033468.2537118.14021843889844001905.stgit@warthog.procyon.org.uk/ # v2
Link: https://lore.kernel.org/r/161340395843.1303470.7355519662919639648.stgit@warthog.procyon.org.uk/ # v3
Link: https://lore.kernel.org/r/161539538693.286939.10171713520419106334.stgit@warthog.procyon.org.uk/ # v4
Link: https://lore.kernel.org/r/161653796447.2770958.1870655382450862155.stgit@warthog.procyon.org.uk/ # v5
Link: https://lore.kernel.org/r/161789078003.6155.17814844411672989942.stgit@warthog.procyon.org.uk/ # v6

1 files changed, 26 insertions, 0 deletions

diff --git a/fs/netfs/read_helper.c b/fs/netfs/read_helper.c
index 30d4bf6bf28a..799eee7f4ee6 100644
--- a/fs/netfs/read_helper.c
+++ b/fs/netfs/read_helper.c
@@ -16,6 +16,8 @@
 #include <linux/task_io_accounting_ops.h>
 #include <linux/netfs.h>
 #include "internal.h"
+#define CREATE_TRACE_POINTS
+#include <trace/events/netfs.h>
 
 MODULE_DESCRIPTION("Network fs support");
 MODULE_AUTHOR("Red Hat, Inc.");
@@ -84,6 +86,7 @@ static void netfs_free_read_request(struct work_struct *work)
 	netfs_rreq_clear_subreqs(rreq, false);
 	if (rreq->netfs_priv)
 		rreq->netfs_ops->cleanup(rreq->mapping, rreq->netfs_priv);
+	trace_netfs_rreq(rreq, netfs_rreq_trace_free);
 	kfree(rreq);
 }
 
@@ -129,6 +132,7 @@ static void __netfs_put_subrequest(struct netfs_read_subrequest *subreq,
 {
 	struct netfs_read_request *rreq = subreq->rreq;
 
+	trace_netfs_sreq(subreq, netfs_sreq_trace_free);
 	kfree(subreq);
 	netfs_put_read_request(rreq, was_async);
 }
@@ -183,6 +187,7 @@ static void netfs_read_from_server(struct netfs_read_request *rreq,
  */
 static void netfs_rreq_completed(struct netfs_read_request *rreq, bool was_async)
 {
+	trace_netfs_rreq(rreq, netfs_rreq_trace_done);
 	netfs_rreq_clear_subreqs(rreq, was_async);
 	netfs_put_read_request(rreq, was_async);
 }
@@ -221,6 +226,8 @@ static void netfs_rreq_unlock(struct netfs_read_request *rreq)
 	iopos = 0;
 	subreq_failed = (subreq->error < 0);
 
+	trace_netfs_rreq(rreq, netfs_rreq_trace_unlock);
+
 	rcu_read_lock();
 	xas_for_each(&xas, page, last_page) {
 		unsigned int pgpos = (page->index - start_page) * PAGE_SIZE;
@@ -281,6 +288,8 @@ static void netfs_rreq_short_read(struct netfs_read_request *rreq,
 	__clear_bit(NETFS_SREQ_SHORT_READ, &subreq->flags);
 	__set_bit(NETFS_SREQ_SEEK_DATA_READ, &subreq->flags);
 
+	trace_netfs_sreq(subreq, netfs_sreq_trace_resubmit_short);
+
 	netfs_get_read_subrequest(subreq);
 	atomic_inc(&rreq->nr_rd_ops);
 	netfs_read_from_server(rreq, subreq);
@@ -296,6 +305,8 @@ static bool netfs_rreq_perform_resubmissions(struct netfs_read_request *rreq)
 
 	WARN_ON(in_interrupt());
 
+	trace_netfs_rreq(rreq, netfs_rreq_trace_resubmit);
+
 	/* We don't want terminating submissions trying to wake us up whilst
 	 * we're still going through the list.
 	 */
@@ -308,6 +319,7 @@ static bool netfs_rreq_perform_resubmissions(struct netfs_read_request *rreq)
 				break;
 			subreq->source = NETFS_DOWNLOAD_FROM_SERVER;
 			subreq->error = 0;
+			trace_netfs_sreq(subreq, netfs_sreq_trace_download_instead);
 			netfs_get_read_subrequest(subreq);
 			atomic_inc(&rreq->nr_rd_ops);
 			netfs_read_from_server(rreq, subreq);
@@ -332,6 +344,8 @@ static bool netfs_rreq_perform_resubmissions(struct netfs_read_request *rreq)
  */
 static void netfs_rreq_assess(struct netfs_read_request *rreq, bool was_async)
 {
+	trace_netfs_rreq(rreq, netfs_rreq_trace_assess);
+
 again:
 	if (!test_bit(NETFS_RREQ_FAILED, &rreq->flags) &&
 	    test_bit(NETFS_RREQ_INCOMPLETE_IO, &rreq->flags)) {
@@ -422,6 +436,8 @@ complete:
 		set_bit(NETFS_RREQ_WRITE_TO_CACHE, &rreq->flags);
 
 out:
+	trace_netfs_sreq(subreq, netfs_sreq_trace_terminated);
+
 	/* If we decrement nr_rd_ops to 0, the ref belongs to us. */
 	u = atomic_dec_return(&rreq->nr_rd_ops);
 	if (u == 0)
@@ -510,6 +526,7 @@ netfs_rreq_prepare_read(struct netfs_read_request *rreq,
 
 out:
 	subreq->source = source;
+	trace_netfs_sreq(subreq, netfs_sreq_trace_prepare);
 	return source;
 }
 
@@ -549,6 +566,7 @@ static bool netfs_rreq_submit_slice(struct netfs_read_request *rreq,
 
 	rreq->submitted += subreq->len;
 
+	trace_netfs_sreq(subreq, netfs_sreq_trace_submit);
 	switch (source) {
 	case NETFS_FILL_WITH_ZEROES:
 		netfs_fill_with_zeroes(rreq, subreq);
@@ -591,6 +609,9 @@ static void netfs_rreq_expand(struct netfs_read_request *rreq,
 		readahead_expand(ractl, rreq->start, rreq->len);
 		rreq->start  = readahead_pos(ractl);
 		rreq->len = readahead_length(ractl);
+
+		trace_netfs_read(rreq, readahead_pos(ractl), readahead_length(ractl),
+				 netfs_read_trace_expanded);
 	}
 }
 
@@ -632,6 +653,9 @@ void netfs_readahead(struct readahead_control *ractl,
 	rreq->start	= readahead_pos(ractl);
 	rreq->len	= readahead_length(ractl);
 
+	trace_netfs_read(rreq, readahead_pos(ractl), readahead_length(ractl),
+			 netfs_read_trace_readahead);
+
 	netfs_rreq_expand(rreq, ractl);
 
 	atomic_set(&rreq->nr_rd_ops, 1);
@@ -698,6 +722,8 @@ int netfs_readpage(struct file *file,
 	rreq->start	= page_index(page) * PAGE_SIZE;
 	rreq->len	= thp_size(page);
 
+	trace_netfs_read(rreq, rreq->start, rreq->len, netfs_read_trace_readpage);
+
 	netfs_get_read_request(rreq);
 
 	atomic_set(&rreq->nr_rd_ops, 1);