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automont: rework expiry to use subprocess rather than thread

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One more step towards a thread-free PID1: let's do automount expiry in a
subprocess rather than a thread.
This commit is contained in:
Lennart Poettering
2023-06-23 10:02:15 +02:00
parent 01ab446c35
commit f7bccef178
1 changed files with 30 additions and 44 deletions
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src/core/automount.c
+30 -44
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@@ -44,22 +44,6 @@ static const UnitActiveState state_translation_table[_AUTOMOUNT_STATE_MAX] = {
[AUTOMOUNT_FAILED] = UNIT_FAILED
};
struct expire_data {
int dev_autofs_fd;
int ioctl_fd;
};
static struct expire_data* expire_data_free(struct expire_data *data) {
if (!data)
return NULL;
safe_close(data->dev_autofs_fd);
safe_close(data->ioctl_fd);
return mfree(data);
}
DEFINE_TRIVIAL_CLEANUP_FUNC(struct expire_data*, expire_data_free);
static int open_dev_autofs(Manager *m);
static int automount_dispatch_io(sd_event_source *s, int fd, uint32_t events, void *userdata);
static int automount_start_expire(Automount *a);
@@ -674,55 +658,57 @@ fail:
automount_enter_dead(a, AUTOMOUNT_FAILURE_RESOURCES);
}
static void *expire_thread(void *p) {
struct autofs_dev_ioctl param;
_cleanup_(expire_data_freep) struct expire_data *data = p;
static int asynchronous_expire(int dev_autofs_fd, int ioctl_fd) {
int r;
assert(data->dev_autofs_fd >= 0);
assert(data->ioctl_fd >= 0);
assert(dev_autofs_fd >= 0);
assert(ioctl_fd >= 0);
init_autofs_dev_ioctl(&param);
param.ioctlfd = data->ioctl_fd;
/* Issue AUTOFS_DEV_IOCTL_EXPIRE in subprocess, asynchronously. Note that we don't keep track of the
* child's PID, we are PID1/autoreaper after all, hence when it dies we'll automatically clean it up
* anyway. */
do {
r = ioctl(data->dev_autofs_fd, AUTOFS_DEV_IOCTL_EXPIRE, &param);
} while (r >= 0);
r = safe_fork_full("(sd-expire)",
/* stdio_fds= */ NULL,
(int[]) { dev_autofs_fd, ioctl_fd },
/* n_except_fds= */ 2,
FORK_RESET_SIGNALS|FORK_CLOSE_ALL_FDS|FORK_REOPEN_LOG,
/* pid= */ NULL);
if (r != 0)
return r;
/* Child */
for (;;) {
struct autofs_dev_ioctl param;
init_autofs_dev_ioctl(&param);
param.ioctlfd = ioctl_fd;
if (ioctl(dev_autofs_fd, AUTOFS_DEV_IOCTL_EXPIRE, &param) < 0)
break;
}
if (errno != EAGAIN)
log_warning_errno(errno, "Failed to expire automount, ignoring: %m");
return NULL;
_exit(EXIT_SUCCESS);
}
static int automount_dispatch_expire(sd_event_source *source, usec_t usec, void *userdata) {
_cleanup_close_ int ioctl_fd = -EBADF;
Automount *a = AUTOMOUNT(userdata);
_cleanup_(expire_data_freep) struct expire_data *data = NULL;
int r;
assert(a);
assert(source == a->expire_event_source);
data = new0(struct expire_data, 1);
if (!data)
return log_oom();
ioctl_fd = open_ioctl_fd(UNIT(a)->manager->dev_autofs_fd, a->where, a->dev_id);
if (ioctl_fd < 0)
return log_unit_error_errno(UNIT(a), ioctl_fd, "Couldn't open autofs ioctl fd: %m");
data->ioctl_fd = -EBADF;
data->dev_autofs_fd = fcntl(UNIT(a)->manager->dev_autofs_fd, F_DUPFD_CLOEXEC, 3);
if (data->dev_autofs_fd < 0)
return log_unit_error_errno(UNIT(a), errno, "Failed to duplicate autofs fd: %m");
data->ioctl_fd = open_ioctl_fd(UNIT(a)->manager->dev_autofs_fd, a->where, a->dev_id);
if (data->ioctl_fd < 0)
return log_unit_error_errno(UNIT(a), data->ioctl_fd, "Couldn't open autofs ioctl fd: %m");
r = asynchronous_job(expire_thread, data);
r = asynchronous_expire(UNIT(a)->manager->dev_autofs_fd, ioctl_fd);
if (r < 0)
return log_unit_error_errno(UNIT(a), r, "Failed to start expire job: %m");
data = NULL;
return automount_start_expire(a);
}