1 /* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */
2
3 /*
4 * mdflush Trace md flush events.
5 *
6 * Copyright (c) 2021~2022 Hengqi Chen
7 *
8 * Based on mdflush(8) from BCC by Brendan Gregg.
9 * 08-Nov-2021 Hengqi Chen Created this.
10 */
11 #include <argp.h>
12 #include <errno.h>
13 #include <signal.h>
14 #include <string.h>
15 #include <time.h>
16
17 #include <bpf/libbpf.h>
18 #include <bpf/bpf.h>
19 #include "mdflush.h"
20 #include "mdflush.skel.h"
21 #include "trace_helpers.h"
22
23 #define PERF_BUFFER_PAGES 16
24 #define PERF_POLL_TIMEOUT_MS 100
25 #define warn(...) fprintf(stderr, __VA_ARGS__)
26
27 static volatile sig_atomic_t exiting = 0;
28 static bool verbose = false;
29
30 const char *argp_program_version = "mdflush 0.1";
31 const char *argp_program_bug_address =
32 "https://github.com/iovisor/bcc/tree/master/libbpf-tools";
33 const char argp_program_doc[] =
34 "Trace md flush events.\n"
35 "\n"
36 "USAGE: mdflush\n";
37
38 static const struct argp_option opts[] = {
39 { "verbose", 'v', NULL, 0, "Verbose debug output" },
40 { NULL, 'h', NULL, OPTION_HIDDEN, "Show the full help" },
41 {},
42 };
43
parse_arg(int key,char * arg,struct argp_state * state)44 static error_t parse_arg(int key, char *arg, struct argp_state *state)
45 {
46 switch (key) {
47 case 'h':
48 argp_state_help(state, stderr, ARGP_HELP_STD_HELP);
49 break;
50 case 'v':
51 verbose = true;
52 break;
53 default:
54 return ARGP_ERR_UNKNOWN;
55 }
56 return 0;
57 }
58
sig_int(int signo)59 static void sig_int(int signo)
60 {
61 exiting = 1;
62 }
63
libbpf_print_fn(enum libbpf_print_level level,const char * format,va_list args)64 static int libbpf_print_fn(enum libbpf_print_level level, const char *format, va_list args)
65 {
66 if (level == LIBBPF_DEBUG && !verbose)
67 return 0;
68 return vfprintf(stderr, format, args);
69 }
70
handle_event(void * ctx,int cpu,void * data,__u32 data_sz)71 static void handle_event(void *ctx, int cpu, void *data, __u32 data_sz)
72 {
73 struct event *e = data;
74 time_t t;
75 struct tm *tm;
76 char ts[32];
77
78 time(&t);
79 tm = localtime(&t);
80 strftime(ts, sizeof(ts), "%H:%M:%S", tm);
81 printf("%-8s %-7d %-16s %-s\n",
82 ts, e->pid, e->comm, e->disk);
83 }
84
handle_lost_events(void * ctx,int cpu,__u64 lost_cnt)85 static void handle_lost_events(void *ctx, int cpu, __u64 lost_cnt)
86 {
87 warn("lost %llu events on CPU #%d\n", lost_cnt, cpu);
88 }
89
main(int argc,char ** argv)90 int main(int argc, char **argv)
91 {
92 static const struct argp argp = {
93 .options = opts,
94 .parser = parse_arg,
95 .doc = argp_program_doc,
96 };
97 struct perf_buffer *pb = NULL;
98 struct mdflush_bpf *obj;
99 int err;
100
101 err = argp_parse(&argp, argc, argv, 0, NULL, NULL);
102 if (err)
103 return err;
104
105 libbpf_set_print(libbpf_print_fn);
106
107 obj = mdflush_bpf__open();
108 if (!obj) {
109 warn("failed to open BPF object\n");
110 return 1;
111 }
112
113 if (fentry_can_attach("md_flush_request", NULL))
114 bpf_program__set_autoload(obj->progs.kprobe_md_flush_request, false);
115 else
116 bpf_program__set_autoload(obj->progs.md_flush_request, false);
117
118 err = mdflush_bpf__load(obj);
119 if (err) {
120 warn("failed to load BPF object: %d\n", err);
121 goto cleanup;
122 }
123
124 err = mdflush_bpf__attach(obj);
125 if (err) {
126 warn("failed to attach BPF programs: %d\n", err);
127 goto cleanup;
128 }
129
130 pb = perf_buffer__new(bpf_map__fd(obj->maps.events), PERF_BUFFER_PAGES,
131 handle_event, handle_lost_events, NULL, NULL);
132 if (!pb) {
133 warn("failed to open perf buffer: %d\n", err);
134 goto cleanup;
135 }
136
137 if (signal(SIGINT, sig_int) == SIG_ERR) {
138 warn("can't set signal handler: %s\n", strerror(errno));
139 err = 1;
140 goto cleanup;
141 }
142
143 printf("Tracing md flush requests... Hit Ctrl-C to end.\n");
144 printf("%-8s %-7s %-16s %-s\n",
145 "TIME", "PID", "COMM", "DEVICE");
146
147 while (!exiting) {
148 err = perf_buffer__poll(pb, PERF_POLL_TIMEOUT_MS);
149 if (err < 0 && err != -EINTR) {
150 warn("error polling perf buffer: %s\n", strerror(-err));
151 goto cleanup;
152 }
153 /* reset err to return 0 if exiting */
154 err = 0;
155 }
156
157 cleanup:
158 perf_buffer__free(pb);
159 mdflush_bpf__destroy(obj);
160
161 return err != 0;
162 }
163