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| | /*
* Copyright (C) 2012-2015 all contributors <cmogstored-public@bogomips.org>
* License: GPLv3 or later (see COPYING for details)
*/
/*
* process management for iostat(1)
* Since iostat(1) watches the entire system, we only spawn it once
* regardless of the number of mog_svc objects we have.
*/
#include "cmogstored.h"
static pid_t iostat_pid;
static time_t iostat_last_fail;
static struct mog_iostat *iostat;
static time_t iostat_fail_timeout = 10;
static void iostat_atexit(void)
{
if (iostat_pid > 0)
kill(iostat_pid, SIGTERM);
}
static int iostat_pipe_init(int *fds)
{
if (pipe2(fds, O_CLOEXEC) < 0) {
PRESERVE_ERRNO( syslog(LOG_ERR, "pipe2() failed: %m") );
/*
* don't retry here, MFS can deal with not getting iostat
* data for a while
*/
if (errno == ENFILE || errno == EMFILE)
PRESERVE_ERRNO( (void)mog_fdmap_expire(5) );
return -1;
}
CHECK(int, 0, mog_set_nonblocking(fds[0], true));
/* fds[1] (write end) stays _blocking_ */
return 0;
}
/* only called in the child process */
static const char * exec_cmd(const char *cmd)
{
time_t last_fail = time(NULL) - iostat_last_fail;
time_t delay = iostat_fail_timeout - last_fail;
if (delay <= 0)
return xasprintf("exec %s", cmd);
syslog(LOG_DEBUG,
"delaying exec of `%s' for %ds due to previous failure",
cmd, (int)delay);
return xasprintf("sleep %d; exec %s", (int)delay, cmd);
}
static void dup2_or_die(int oldfd, int newfd, const char *errdesc)
{
int rc;
do
rc = dup2(oldfd, newfd);
while (rc < 0 && (errno == EINTR || errno == EBUSY));
if (rc < 0) {
syslog(LOG_CRIT, "dup2(%s) failed: %m", errdesc);
abort();
}
}
static void preexec_redirect(int out_fd)
{
int null_fd;
dup2_or_die(out_fd, STDOUT_FILENO, "iostat_pipe[1],STDOUT");
mog_close(out_fd);
null_fd = open("/dev/null", O_RDONLY);
if (null_fd < 0) {
syslog(LOG_CRIT, "open(/dev/null) failed: %m");
abort();
}
dup2_or_die(null_fd, STDIN_FILENO, "/dev/null,STDIN");
mog_close(null_fd);
/* don't touch stderr */
}
static pid_t iostat_fork_exec(int out_fd)
{
/* rely on /bin/sh to parse iostat command-line args */
const char *cmd = getenv("MOG_IOSTAT_CMD");
if (!cmd)
cmd = "iostat -dx 1 30";
cmd = exec_cmd(cmd);
iostat_pid = fork();
if (iostat_pid < 0) {
syslog(LOG_ERR, "fork() for iostat failed: %m");
} else if (iostat_pid > 0) {
mog_process_register(iostat_pid, MOG_PROC_IOSTAT);
mog_close(out_fd);
} else {
/* child */
preexec_redirect(out_fd);
if (! mog_cloexec_atomic)
mog_cloexec_from(STDERR_FILENO + 1);
mog_intr_enable();
execl("/bin/sh", "sh", "-c", cmd, (char *)NULL);
syslog(LOG_CRIT, "execl(%s) failed: %m", cmd);
abort();
}
mog_free(cmd);
return iostat_pid;
}
bool mog_iostat_respawn(int oldstatus)
{
int fds[2];
struct mog_fd *mfd;
if (WIFEXITED(oldstatus) && WEXITSTATUS(oldstatus) == 0) {
/* syslog(LOG_DEBUG, "iostat done, restarting"); */
} else {
iostat_last_fail = time(NULL);
syslog(LOG_WARNING,
"iostat done (pid=%d, status=%d), will retry in %ds",
(int)iostat_pid, oldstatus, (int)iostat_fail_timeout);
}
iostat_pid = 0;
if (iostat_pipe_init(fds) < 0)
return false; /* EMFILE || ENFILE */
if (iostat_fork_exec(fds[1]) < 0)
return false; /* fork() failure */
assert(fds[0] >= 0 && "invalid FD");
mfd = mog_fd_init(fds[0], MOG_FD_TYPE_IOSTAT);
if (iostat == NULL)
atexit(iostat_atexit);
iostat = &mfd->as.iostat;
iostat->queue = mog_notify_queue;
mog_iostat_init(iostat);
mog_idleq_add(iostat->queue, mfd, MOG_QEV_RD);
return true;
}
|