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/* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */
/*
* mdflush Trace md flush events.
*
* Copyright (c) 2021~2022 Hengqi Chen
*
* Based on mdflush(8) from BCC by Brendan Gregg.
* 08-Nov-2021 Hengqi Chen Created this.
*/
#include <argp.h>
#include <errno.h>
#include <signal.h>
#include <string.h>
#include <time.h>
#include <bpf/libbpf.h>
#include <bpf/bpf.h>
#include "mdflush.h"
#include "mdflush.skel.h"
#include "trace_helpers.h"
#define PERF_BUFFER_PAGES 16
#define PERF_POLL_TIMEOUT_MS 100
#define warn(...) fprintf(stderr, __VA_ARGS__)
static volatile sig_atomic_t exiting = 0;
static bool verbose = false;
const char *argp_program_version = "mdflush 0.1";
const char *argp_program_bug_address =
"https://github.com/iovisor/bcc/tree/master/libbpf-tools";
const char argp_program_doc[] =
"Trace md flush events.\n"
"\n"
"USAGE: mdflush\n";
static const struct argp_option opts[] = {
{ "verbose", 'v', NULL, 0, "Verbose debug output", 0 },
{ NULL, 'h', NULL, OPTION_HIDDEN, "Show the full help", 0 },
{},
};
static error_t parse_arg(int key, char *arg, struct argp_state *state)
{
switch (key) {
case 'h':
argp_state_help(state, stderr, ARGP_HELP_STD_HELP);
break;
case 'v':
verbose = true;
break;
default:
return ARGP_ERR_UNKNOWN;
}
return 0;
}
static void sig_int(int signo)
{
exiting = 1;
}
static int libbpf_print_fn(enum libbpf_print_level level, const char *format, va_list args)
{
if (level == LIBBPF_DEBUG && !verbose)
return 0;
return vfprintf(stderr, format, args);
}
static void handle_event(void *ctx, int cpu, void *data, __u32 data_sz)
{
struct event *e = data;
time_t t;
struct tm *tm;
char ts[32];
time(&t);
tm = localtime(&t);
strftime(ts, sizeof(ts), "%H:%M:%S", tm);
printf("%-8s %-7d %-16s %-s\n",
ts, e->pid, e->comm, e->disk);
}
static void handle_lost_events(void *ctx, int cpu, __u64 lost_cnt)
{
warn("lost %llu events on CPU #%d\n", lost_cnt, cpu);
}
int main(int argc, char **argv)
{
static const struct argp argp = {
.options = opts,
.parser = parse_arg,
.doc = argp_program_doc,
};
struct perf_buffer *pb = NULL;
struct mdflush_bpf *obj;
int err;
err = argp_parse(&argp, argc, argv, 0, NULL, NULL);
if (err)
return err;
libbpf_set_print(libbpf_print_fn);
obj = mdflush_bpf__open();
if (!obj) {
warn("failed to open BPF object\n");
return 1;
}
if (fentry_can_attach("md_flush_request", NULL))
bpf_program__set_autoload(obj->progs.kprobe_md_flush_request, false);
else
bpf_program__set_autoload(obj->progs.md_flush_request, false);
err = mdflush_bpf__load(obj);
if (err) {
warn("failed to load BPF object: %d\n", err);
goto cleanup;
}
err = mdflush_bpf__attach(obj);
if (err) {
warn("failed to attach BPF programs: %d\n", err);
goto cleanup;
}
pb = perf_buffer__new(bpf_map__fd(obj->maps.events), PERF_BUFFER_PAGES,
handle_event, handle_lost_events, NULL, NULL);
if (!pb) {
warn("failed to open perf buffer: %d\n", err);
goto cleanup;
}
if (signal(SIGINT, sig_int) == SIG_ERR) {
warn("can't set signal handler: %s\n", strerror(errno));
err = 1;
goto cleanup;
}
printf("Tracing md flush requests... Hit Ctrl-C to end.\n");
printf("%-8s %-7s %-16s %-s\n",
"TIME", "PID", "COMM", "DEVICE");
while (!exiting) {
err = perf_buffer__poll(pb, PERF_POLL_TIMEOUT_MS);
if (err < 0 && err != -EINTR) {
warn("error polling perf buffer: %s\n", strerror(-err));
goto cleanup;
}
/* reset err to return 0 if exiting */
err = 0;
}
cleanup:
perf_buffer__free(pb);
mdflush_bpf__destroy(obj);
return err != 0;
}
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