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authorKarel Zak <kzak@redhat.com>2015-06-01 13:48:01 +0200
committerKarel Zak <kzak@redhat.com>2015-09-14 09:12:31 +0200
commitd379d44255469f03994832ab5821bf1b9034f4dc (patch)
tree27194587d38c4ea1333e67caed64202ecca9ec20 /src/core
parent5669ef3644e3044036eeaaf6bb4b1a6a7e63130c (diff)
mount: use libmount to monitor mountinfo & utab
The current implementation directly monitor /proc/self/mountinfo and /run/mount/utab files. It's really not optimal because utab file is private libmount stuff without any official guaranteed semantic. The libmount since v2.26 provides API to monitor mount kernel & userspace changes and since v2.27 the monitor is usable for non-root users too. This patch replaces the current implementation with libmount based solution. Signed-off-by: Karel Zak <kzak@redhat.com>
Diffstat (limited to 'src/core')
-rw-r--r--src/core/manager.c4
-rw-r--r--src/core/manager.h5
-rw-r--r--src/core/mount.c106
3 files changed, 41 insertions, 74 deletions
diff --git a/src/core/manager.c b/src/core/manager.c
index 8e518fbaaf..bb1009081a 100644
--- a/src/core/manager.c
+++ b/src/core/manager.c
@@ -571,8 +571,8 @@ int manager_new(ManagerRunningAs running_as, bool test_run, Manager **_m) {
m->idle_pipe[0] = m->idle_pipe[1] = m->idle_pipe[2] = m->idle_pipe[3] = -1;
m->pin_cgroupfs_fd = m->notify_fd = m->signal_fd = m->time_change_fd =
- m->dev_autofs_fd = m->private_listen_fd = m->kdbus_fd = m->utab_inotify_fd =
- m->cgroup_inotify_fd = -1;
+ m->dev_autofs_fd = m->private_listen_fd = m->kdbus_fd = m->cgroup_inotify_fd = -1;
+
m->current_job_id = 1; /* start as id #1, so that we can leave #0 around as "null-like" value */
m->ask_password_inotify_fd = -1;
diff --git a/src/core/manager.h b/src/core/manager.h
index 5cf0dbd508..7b896f9bc7 100644
--- a/src/core/manager.h
+++ b/src/core/manager.h
@@ -23,6 +23,7 @@
#include <stdbool.h>
#include <stdio.h>
+#include <libmount.h>
#include "sd-bus.h"
#include "sd-event.h"
@@ -176,10 +177,8 @@ struct Manager {
Hashmap *devices_by_sysfs;
/* Data specific to the mount subsystem */
- FILE *proc_self_mountinfo;
+ struct libmnt_monitor *mount_monitor;
sd_event_source *mount_event_source;
- int utab_inotify_fd;
- sd_event_source *mount_utab_event_source;
/* Data specific to the swap filesystem */
FILE *proc_swaps;
diff --git a/src/core/mount.c b/src/core/mount.c
index 1f02aa5566..e7aae6e19a 100644
--- a/src/core/mount.c
+++ b/src/core/mount.c
@@ -23,8 +23,6 @@
#include <stdio.h>
#include <sys/epoll.h>
#include <signal.h>
-#include <libmount.h>
-#include <sys/inotify.h>
#include "manager.h"
#include "unit.h"
@@ -1535,13 +1533,13 @@ static int mount_load_proc_self_mountinfo(Manager *m, bool set_flags) {
}
static void mount_shutdown(Manager *m) {
+
assert(m);
m->mount_event_source = sd_event_source_unref(m->mount_event_source);
- m->mount_utab_event_source = sd_event_source_unref(m->mount_utab_event_source);
- m->proc_self_mountinfo = safe_fclose(m->proc_self_mountinfo);
- m->utab_inotify_fd = safe_close(m->utab_inotify_fd);
+ mnt_unref_monitor(m->mount_monitor);
+ m->mount_monitor = NULL;
}
static int mount_get_timeout(Unit *u, uint64_t *timeout) {
@@ -1560,53 +1558,41 @@ static int mount_get_timeout(Unit *u, uint64_t *timeout) {
static int mount_enumerate(Manager *m) {
int r;
+
assert(m);
mnt_init_debug(0);
- if (!m->proc_self_mountinfo) {
- m->proc_self_mountinfo = fopen("/proc/self/mountinfo", "re");
- if (!m->proc_self_mountinfo)
- return -errno;
+ if (!m->mount_monitor) {
+ int fd;
- r = sd_event_add_io(m->event, &m->mount_event_source, fileno(m->proc_self_mountinfo), EPOLLPRI, mount_dispatch_io, m);
- if (r < 0)
+ m->mount_monitor = mnt_new_monitor();
+ if (!m->mount_monitor) {
+ r = -ENOMEM;
goto fail;
+ }
- /* Dispatch this before we dispatch SIGCHLD, so that
- * we always get the events from /proc/self/mountinfo
- * before the SIGCHLD of /usr/bin/mount. */
- r = sd_event_source_set_priority(m->mount_event_source, -10);
+ r = mnt_monitor_enable_kernel(m->mount_monitor, 1);
if (r < 0)
goto fail;
-
- (void) sd_event_source_set_description(m->mount_event_source, "mount-mountinfo-dispatch");
- }
-
- if (m->utab_inotify_fd < 0) {
- m->utab_inotify_fd = inotify_init1(IN_NONBLOCK|IN_CLOEXEC);
- if (m->utab_inotify_fd < 0) {
- r = -errno;
+ r = mnt_monitor_enable_userspace(m->mount_monitor, 1, NULL);
+ if (r < 0)
goto fail;
- }
-
- (void) mkdir_p_label("/run/mount", 0755);
- r = inotify_add_watch(m->utab_inotify_fd, "/run/mount", IN_MOVED_TO);
- if (r < 0) {
- r = -errno;
+ /* mnt_unref_monitor() will close the fd */
+ fd = r = mnt_monitor_get_fd(m->mount_monitor);
+ if (r < 0)
goto fail;
- }
- r = sd_event_add_io(m->event, &m->mount_utab_event_source, m->utab_inotify_fd, EPOLLIN, mount_dispatch_io, m);
+ r = sd_event_add_io(m->event, &m->mount_event_source, fd, EPOLLIN, mount_dispatch_io, m);
if (r < 0)
goto fail;
- r = sd_event_source_set_priority(m->mount_utab_event_source, -10);
+ r = sd_event_source_set_priority(m->mount_event_source, -10);
if (r < 0)
goto fail;
- (void) sd_event_source_set_description(m->mount_utab_event_source, "mount-utab-dispatch");
+ (void) sd_event_source_set_description(m->mount_event_source, "mount-monitor-dispatch");
}
r = mount_load_proc_self_mountinfo(m, false);
@@ -1629,45 +1615,27 @@ static int mount_dispatch_io(sd_event_source *source, int fd, uint32_t revents,
int r;
assert(m);
- assert(revents & (EPOLLPRI | EPOLLIN));
-
- /* The manager calls this for every fd event happening on the
- * /proc/self/mountinfo file, which informs us about mounting
- * table changes, and for /run/mount events which we watch
- * for mount options. */
+ assert(revents & EPOLLIN);
- if (fd == m->utab_inotify_fd) {
+ if (fd == mnt_monitor_get_fd(m->mount_monitor)) {
bool rescan = false;
- /* FIXME: We *really* need to replace this with
- * libmount's own API for this, we should not hardcode
- * internal behaviour of libmount here. */
-
- for (;;) {
- union inotify_event_buffer buffer;
- struct inotify_event *e;
- ssize_t l;
-
- l = read(fd, &buffer, sizeof(buffer));
- if (l < 0) {
- if (errno == EAGAIN || errno == EINTR)
- break;
-
- log_error_errno(errno, "Failed to read utab inotify: %m");
- break;
- }
-
- FOREACH_INOTIFY_EVENT(e, buffer, l) {
- /* Only care about changes to utab,
- * but we have to monitor the
- * directory to reliably get
- * notifications about when utab is
- * replaced using rename(2) */
- if ((e->mask & IN_Q_OVERFLOW) || streq(e->name, "utab"))
- rescan = true;
- }
- }
-
+ /* Drain all events and verify that the event is valid.
+ *
+ * Note that libmount also monitors /run/mount mkdir if the
+ * directory does not exist yet. The mkdir may generate event
+ * which is irrelevant for us.
+ *
+ * error: r < 0; valid: r == 0, false positive: rc == 1 */
+ do {
+ r = mnt_monitor_next_change(m->mount_monitor, NULL, NULL);
+ if (r == 0)
+ rescan = true;
+ else if (r < 0)
+ return log_error_errno(r, "Failed to drain libmount events");
+ } while (r == 0);
+
+ log_debug("libmount event [rescan: %s]", yes_no(rescan));
if (!rescan)
return 0;
}