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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 <[email protected]> Reviewed-and-tested-by: Jeff Layton <[email protected]> Tested-by: Dave Wysochanski <[email protected]> Tested-By: Marc Dionne <[email protected]> cc: Matthew Wilcox <[email protected]> cc: [email protected] cc: [email protected] cc: [email protected] cc: [email protected] cc: [email protected] cc: [email protected] cc: [email protected] cc: [email protected] 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
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‎fs/netfs/read_helper.c

Lines changed: 26 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -16,6 +16,8 @@
1616
#include <linux/task_io_accounting_ops.h>
1717
#include <linux/netfs.h>
1818
#include "internal.h"
19+
#define CREATE_TRACE_POINTS
20+
#include <trace/events/netfs.h>
1921

2022
MODULE_DESCRIPTION("Network fs support");
2123
MODULE_AUTHOR("Red Hat, Inc.");
@@ -84,6 +86,7 @@ static void netfs_free_read_request(struct work_struct *work)
8486
netfs_rreq_clear_subreqs(rreq, false);
8587
if (rreq->netfs_priv)
8688
rreq->netfs_ops->cleanup(rreq->mapping, rreq->netfs_priv);
89+
trace_netfs_rreq(rreq, netfs_rreq_trace_free);
8790
kfree(rreq);
8891
}
8992

@@ -129,6 +132,7 @@ static void __netfs_put_subrequest(struct netfs_read_subrequest *subreq,
129132
{
130133
struct netfs_read_request *rreq = subreq->rreq;
131134

135+
trace_netfs_sreq(subreq, netfs_sreq_trace_free);
132136
kfree(subreq);
133137
netfs_put_read_request(rreq, was_async);
134138
}
@@ -183,6 +187,7 @@ static void netfs_read_from_server(struct netfs_read_request *rreq,
183187
*/
184188
static void netfs_rreq_completed(struct netfs_read_request *rreq, bool was_async)
185189
{
190+
trace_netfs_rreq(rreq, netfs_rreq_trace_done);
186191
netfs_rreq_clear_subreqs(rreq, was_async);
187192
netfs_put_read_request(rreq, was_async);
188193
}
@@ -221,6 +226,8 @@ static void netfs_rreq_unlock(struct netfs_read_request *rreq)
221226
iopos = 0;
222227
subreq_failed = (subreq->error < 0);
223228

229+
trace_netfs_rreq(rreq, netfs_rreq_trace_unlock);
230+
224231
rcu_read_lock();
225232
xas_for_each(&xas, page, last_page) {
226233
unsigned int pgpos = (page->index - start_page) * PAGE_SIZE;
@@ -281,6 +288,8 @@ static void netfs_rreq_short_read(struct netfs_read_request *rreq,
281288
__clear_bit(NETFS_SREQ_SHORT_READ, &subreq->flags);
282289
__set_bit(NETFS_SREQ_SEEK_DATA_READ, &subreq->flags);
283290

291+
trace_netfs_sreq(subreq, netfs_sreq_trace_resubmit_short);
292+
284293
netfs_get_read_subrequest(subreq);
285294
atomic_inc(&rreq->nr_rd_ops);
286295
netfs_read_from_server(rreq, subreq);
@@ -296,6 +305,8 @@ static bool netfs_rreq_perform_resubmissions(struct netfs_read_request *rreq)
296305

297306
WARN_ON(in_interrupt());
298307

308+
trace_netfs_rreq(rreq, netfs_rreq_trace_resubmit);
309+
299310
/* We don't want terminating submissions trying to wake us up whilst
300311
* we're still going through the list.
301312
*/
@@ -308,6 +319,7 @@ static bool netfs_rreq_perform_resubmissions(struct netfs_read_request *rreq)
308319
break;
309320
subreq->source = NETFS_DOWNLOAD_FROM_SERVER;
310321
subreq->error = 0;
322+
trace_netfs_sreq(subreq, netfs_sreq_trace_download_instead);
311323
netfs_get_read_subrequest(subreq);
312324
atomic_inc(&rreq->nr_rd_ops);
313325
netfs_read_from_server(rreq, subreq);
@@ -332,6 +344,8 @@ static bool netfs_rreq_perform_resubmissions(struct netfs_read_request *rreq)
332344
*/
333345
static void netfs_rreq_assess(struct netfs_read_request *rreq, bool was_async)
334346
{
347+
trace_netfs_rreq(rreq, netfs_rreq_trace_assess);
348+
335349
again:
336350
if (!test_bit(NETFS_RREQ_FAILED, &rreq->flags) &&
337351
test_bit(NETFS_RREQ_INCOMPLETE_IO, &rreq->flags)) {
@@ -422,6 +436,8 @@ void netfs_subreq_terminated(struct netfs_read_subrequest *subreq,
422436
set_bit(NETFS_RREQ_WRITE_TO_CACHE, &rreq->flags);
423437

424438
out:
439+
trace_netfs_sreq(subreq, netfs_sreq_trace_terminated);
440+
425441
/* If we decrement nr_rd_ops to 0, the ref belongs to us. */
426442
u = atomic_dec_return(&rreq->nr_rd_ops);
427443
if (u == 0)
@@ -510,6 +526,7 @@ netfs_rreq_prepare_read(struct netfs_read_request *rreq,
510526

511527
out:
512528
subreq->source = source;
529+
trace_netfs_sreq(subreq, netfs_sreq_trace_prepare);
513530
return source;
514531
}
515532

@@ -549,6 +566,7 @@ static bool netfs_rreq_submit_slice(struct netfs_read_request *rreq,
549566

550567
rreq->submitted += subreq->len;
551568

569+
trace_netfs_sreq(subreq, netfs_sreq_trace_submit);
552570
switch (source) {
553571
case NETFS_FILL_WITH_ZEROES:
554572
netfs_fill_with_zeroes(rreq, subreq);
@@ -591,6 +609,9 @@ static void netfs_rreq_expand(struct netfs_read_request *rreq,
591609
readahead_expand(ractl, rreq->start, rreq->len);
592610
rreq->start = readahead_pos(ractl);
593611
rreq->len = readahead_length(ractl);
612+
613+
trace_netfs_read(rreq, readahead_pos(ractl), readahead_length(ractl),
614+
netfs_read_trace_expanded);
594615
}
595616
}
596617

@@ -632,6 +653,9 @@ void netfs_readahead(struct readahead_control *ractl,
632653
rreq->start = readahead_pos(ractl);
633654
rreq->len = readahead_length(ractl);
634655

656+
trace_netfs_read(rreq, readahead_pos(ractl), readahead_length(ractl),
657+
netfs_read_trace_readahead);
658+
635659
netfs_rreq_expand(rreq, ractl);
636660

637661
atomic_set(&rreq->nr_rd_ops, 1);
@@ -698,6 +722,8 @@ int netfs_readpage(struct file *file,
698722
rreq->start = page_index(page) * PAGE_SIZE;
699723
rreq->len = thp_size(page);
700724

725+
trace_netfs_read(rreq, rreq->start, rreq->len, netfs_read_trace_readpage);
726+
701727
netfs_get_read_request(rreq);
702728

703729
atomic_set(&rreq->nr_rd_ops, 1);

‎include/linux/netfs.h

Lines changed: 1 addition & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -124,6 +124,7 @@ struct netfs_read_request {
124124
struct list_head subrequests; /* Requests to fetch I/O from disk or net */
125125
void *netfs_priv; /* Private data for the netfs */
126126
unsigned int debug_id;
127+
unsigned int cookie_debug_id;
127128
atomic_t nr_rd_ops; /* Number of read ops in progress */
128129
size_t submitted; /* Amount submitted for I/O so far */
129130
size_t len; /* Length of the request */

‎include/trace/events/netfs.h

Lines changed: 199 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,199 @@
1+
/* SPDX-License-Identifier: GPL-2.0-or-later */
2+
/* Network filesystem support module tracepoints
3+
*
4+
* Copyright (C) 2021 Red Hat, Inc. All Rights Reserved.
5+
* Written by David Howells ([email protected])
6+
*/
7+
#undef TRACE_SYSTEM
8+
#define TRACE_SYSTEM netfs
9+
10+
#if !defined(_TRACE_NETFS_H) || defined(TRACE_HEADER_MULTI_READ)
11+
#define _TRACE_NETFS_H
12+
13+
#include <linux/tracepoint.h>
14+
15+
/*
16+
* Define enums for tracing information.
17+
*/
18+
#ifndef __NETFS_DECLARE_TRACE_ENUMS_ONCE_ONLY
19+
#define __NETFS_DECLARE_TRACE_ENUMS_ONCE_ONLY
20+
21+
enum netfs_read_trace {
22+
netfs_read_trace_expanded,
23+
netfs_read_trace_readahead,
24+
netfs_read_trace_readpage,
25+
};
26+
27+
enum netfs_rreq_trace {
28+
netfs_rreq_trace_assess,
29+
netfs_rreq_trace_done,
30+
netfs_rreq_trace_free,
31+
netfs_rreq_trace_resubmit,
32+
netfs_rreq_trace_unlock,
33+
netfs_rreq_trace_unmark,
34+
netfs_rreq_trace_write,
35+
};
36+
37+
enum netfs_sreq_trace {
38+
netfs_sreq_trace_download_instead,
39+
netfs_sreq_trace_free,
40+
netfs_sreq_trace_prepare,
41+
netfs_sreq_trace_resubmit_short,
42+
netfs_sreq_trace_submit,
43+
netfs_sreq_trace_terminated,
44+
netfs_sreq_trace_write,
45+
netfs_sreq_trace_write_term,
46+
};
47+
48+
#endif
49+
50+
#define netfs_read_traces \
51+
EM(netfs_read_trace_expanded, "EXPANDED ") \
52+
EM(netfs_read_trace_readahead, "READAHEAD") \
53+
E_(netfs_read_trace_readpage, "READPAGE ")
54+
55+
#define netfs_rreq_traces \
56+
EM(netfs_rreq_trace_assess, "ASSESS") \
57+
EM(netfs_rreq_trace_done, "DONE ") \
58+
EM(netfs_rreq_trace_free, "FREE ") \
59+
EM(netfs_rreq_trace_resubmit, "RESUBM") \
60+
EM(netfs_rreq_trace_unlock, "UNLOCK") \
61+
EM(netfs_rreq_trace_unmark, "UNMARK") \
62+
E_(netfs_rreq_trace_write, "WRITE ")
63+
64+
#define netfs_sreq_sources \
65+
EM(NETFS_FILL_WITH_ZEROES, "ZERO") \
66+
EM(NETFS_DOWNLOAD_FROM_SERVER, "DOWN") \
67+
EM(NETFS_READ_FROM_CACHE, "READ") \
68+
E_(NETFS_INVALID_READ, "INVL") \
69+
70+
#define netfs_sreq_traces \
71+
EM(netfs_sreq_trace_download_instead, "RDOWN") \
72+
EM(netfs_sreq_trace_free, "FREE ") \
73+
EM(netfs_sreq_trace_prepare, "PREP ") \
74+
EM(netfs_sreq_trace_resubmit_short, "SHORT") \
75+
EM(netfs_sreq_trace_submit, "SUBMT") \
76+
EM(netfs_sreq_trace_terminated, "TERM ") \
77+
EM(netfs_sreq_trace_write, "WRITE") \
78+
E_(netfs_sreq_trace_write_term, "WTERM")
79+
80+
81+
/*
82+
* Export enum symbols via userspace.
83+
*/
84+
#undef EM
85+
#undef E_
86+
#define EM(a, b) TRACE_DEFINE_ENUM(a);
87+
#define E_(a, b) TRACE_DEFINE_ENUM(a);
88+
89+
netfs_read_traces;
90+
netfs_rreq_traces;
91+
netfs_sreq_sources;
92+
netfs_sreq_traces;
93+
94+
/*
95+
* Now redefine the EM() and E_() macros to map the enums to the strings that
96+
* will be printed in the output.
97+
*/
98+
#undef EM
99+
#undef E_
100+
#define EM(a, b) { a, b },
101+
#define E_(a, b) { a, b }
102+
103+
TRACE_EVENT(netfs_read,
104+
TP_PROTO(struct netfs_read_request *rreq,
105+
loff_t start, size_t len,
106+
enum netfs_read_trace what),
107+
108+
TP_ARGS(rreq, start, len, what),
109+
110+
TP_STRUCT__entry(
111+
__field(unsigned int, rreq )
112+
__field(unsigned int, cookie )
113+
__field(loff_t, start )
114+
__field(size_t, len )
115+
__field(enum netfs_read_trace, what )
116+
),
117+
118+
TP_fast_assign(
119+
__entry->rreq = rreq->debug_id;
120+
__entry->cookie = rreq->cookie_debug_id;
121+
__entry->start = start;
122+
__entry->len = len;
123+
__entry->what = what;
124+
),
125+
126+
TP_printk("R=%08x %s c=%08x s=%llx %zx",
127+
__entry->rreq,
128+
__print_symbolic(__entry->what, netfs_read_traces),
129+
__entry->cookie,
130+
__entry->start, __entry->len)
131+
);
132+
133+
TRACE_EVENT(netfs_rreq,
134+
TP_PROTO(struct netfs_read_request *rreq,
135+
enum netfs_rreq_trace what),
136+
137+
TP_ARGS(rreq, what),
138+
139+
TP_STRUCT__entry(
140+
__field(unsigned int, rreq )
141+
__field(unsigned short, flags )
142+
__field(enum netfs_rreq_trace, what )
143+
),
144+
145+
TP_fast_assign(
146+
__entry->rreq = rreq->debug_id;
147+
__entry->flags = rreq->flags;
148+
__entry->what = what;
149+
),
150+
151+
TP_printk("R=%08x %s f=%02x",
152+
__entry->rreq,
153+
__print_symbolic(__entry->what, netfs_rreq_traces),
154+
__entry->flags)
155+
);
156+
157+
TRACE_EVENT(netfs_sreq,
158+
TP_PROTO(struct netfs_read_subrequest *sreq,
159+
enum netfs_sreq_trace what),
160+
161+
TP_ARGS(sreq, what),
162+
163+
TP_STRUCT__entry(
164+
__field(unsigned int, rreq )
165+
__field(unsigned short, index )
166+
__field(short, error )
167+
__field(unsigned short, flags )
168+
__field(enum netfs_read_source, source )
169+
__field(enum netfs_sreq_trace, what )
170+
__field(size_t, len )
171+
__field(size_t, transferred )
172+
__field(loff_t, start )
173+
),
174+
175+
TP_fast_assign(
176+
__entry->rreq = sreq->rreq->debug_id;
177+
__entry->index = sreq->debug_index;
178+
__entry->error = sreq->error;
179+
__entry->flags = sreq->flags;
180+
__entry->source = sreq->source;
181+
__entry->what = what;
182+
__entry->len = sreq->len;
183+
__entry->transferred = sreq->transferred;
184+
__entry->start = sreq->start;
185+
),
186+
187+
TP_printk("R=%08x[%u] %s %s f=%02x s=%llx %zx/%zx e=%d",
188+
__entry->rreq, __entry->index,
189+
__print_symbolic(__entry->what, netfs_sreq_traces),
190+
__print_symbolic(__entry->source, netfs_sreq_sources),
191+
__entry->flags,
192+
__entry->start, __entry->transferred, __entry->len,
193+
__entry->error)
194+
);
195+
196+
#endif /* _TRACE_NETFS_H */
197+
198+
/* This part must be outside protection */
199+
#include <trace/define_trace.h>

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