umount: Adding unmount functions to be used in shutdown

This functions will:
   - umount all mount points that aren't API
   - remount read-only all mount points that can't be umounted
   - umount all swap devices.
   - detach all loopback devices

TODO:
   - umount dms

Mountpoints are being read from /proc/self/mountinfo.
Swaps are being read from /proc/swaps.
Loop devices from /sys/class/block/loop*.

2 files changed, 441 insertions, 0 deletions

diff --git a/src/umount.c b/src/umount.c
new file mode 100644
index 0000000000..4842d403ae
--- /dev/null
+++ b/src/umount.c
@@ -0,0 +1,410 @@
+/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
+
+/***
+  This file is part of systemd.
+
+  Copyright 2010 ProFUSION embedded systems
+
+  systemd is free software; you can redistribute it and/or modify it
+  under the terms of the GNU General Public License as published by
+  the Free Software Foundation; either version 2 of the License, or
+  (at your option) any later version.
+
+  systemd is distributed in the hope that it will be useful, but
+  WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+  General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with systemd; If not, see <http://www.gnu.org/licenses/>.
+***/
+
+#include <errno.h>
+#include <fcntl.h>
+#include <string.h>
+#include <sys/mount.h>
+#include <sys/swap.h>
+#include <unistd.h>
+#include <linux/loop.h>
+#include <libudev.h>
+
+#include "list.h"
+#include "mount-setup.h"
+#include "umount.h"
+#include "util.h"
+
+typedef struct MountPoint {
+        char *path;
+        bool read_only;
+        LIST_FIELDS (struct MountPoint, mount_point);
+} MountPoint;
+
+static MountPoint *mount_point_alloc(char *path) {
+        MountPoint *mp;
+
+        if (!(mp = new(MountPoint, 1)))
+                return NULL;
+
+        mp->path = path;
+        mp->read_only = false;
+
+        return mp;
+}
+
+static void mount_point_remove_and_free(MountPoint *mount_point, MountPoint **mount_point_list_head) {
+        LIST_REMOVE(MountPoint, mount_point, *mount_point_list_head, mount_point);
+
+        free(mount_point->path);
+        free(mount_point);
+}
+
+static void mount_points_list_free(MountPoint **mount_point_list_head) {
+        while (*mount_point_list_head)
+                mount_point_remove_and_free(*mount_point_list_head, mount_point_list_head);
+}
+
+static int mount_points_list_get(MountPoint **mount_point_list_head) {
+        FILE *proc_self_mountinfo;
+        char *path, *p;
+        unsigned int i;
+        int r;
+
+        if (!(proc_self_mountinfo = fopen("/proc/self/mountinfo", "re")))
+                return -errno;
+
+        for (i = 1;; i++) {
+                int k;
+                MountPoint *mp;
+
+                path = p = NULL;
+
+                if ((k = fscanf(proc_self_mountinfo,
+                                "%*s "       /* (1) mount id */
+                                "%*s "       /* (2) parent id */
+                                "%*s "       /* (3) major:minor */
+                                "%*s "       /* (4) root */
+                                "%ms "       /* (5) mount point */
+                                "%*s"        /* (6) mount options */
+                                "%*[^-]"     /* (7) optional fields */
+                                "- "         /* (8) separator */
+                                "%*s "       /* (9) file system type */
+                                "%*s"        /* (10) mount source */
+                                "%*s"        /* (11) mount options 2 */
+                                "%*[^\n]",   /* some rubbish at the end */
+                                &path)) != 1) {
+                        if (k == EOF)
+                                break;
+
+                        log_warning("Failed to parse /proc/self/mountinfo:%u.", i);
+
+                        free(path);
+                        continue;
+                }
+
+                if (mount_point_is_api(path)) {
+                        free(path);
+                        continue;
+                }
+
+                if (!(p = cunescape(path))) {
+                        r = -ENOMEM;
+                        goto finish;
+                }
+
+                if (!(mp = mount_point_alloc(p))) {
+                        r = -ENOMEM;
+                        goto finish;
+                }
+                LIST_PREPEND(MountPoint, mount_point, *mount_point_list_head, mp);
+
+                free(path);
+        }
+
+        r = 0;
+
+finish:
+        fclose(proc_self_mountinfo);
+
+        free(path);
+
+        return r;
+}
+
+static int swap_list_get(MountPoint **swap_list_head) {
+        FILE *proc_swaps;
+        unsigned int i;
+        int r;
+
+        if (!(proc_swaps = fopen("/proc/swaps", "re")))
+                return -errno;
+
+        (void) fscanf(proc_swaps, "%*s %*s %*s %*s %*s\n");
+
+        for (i = 2;; i++) {
+                MountPoint *swap;
+                char *dev = NULL, *d;
+                int k;
+
+                if ((k = fscanf(proc_swaps,
+                                "%ms " /* device/file */
+                                "%*s " /* type of swap */
+                                "%*s " /* swap size */
+                                "%*s " /* used */
+                                "%*s\n", /* priority */
+                                &dev)) != 1) {
+
+                        if (k == EOF)
+                                break;
+
+                        log_warning("Failed to parse /proc/swaps:%u.", i);
+
+                        free(dev);
+                        continue;
+                }
+
+                if (endswith(dev, "(deleted)")) {
+                        free(dev);
+                        continue;
+                }
+
+                d = cunescape(dev);
+                free(dev);
+
+                if (!d) {
+                        r = -ENOMEM;
+                        goto finish;
+                }
+
+                swap = mount_point_alloc(d);
+                if (!swap) {
+                        free(d);
+                        r = -ENOMEM;
+                        goto finish;
+                }
+
+                LIST_PREPEND(MountPoint, mount_point, *swap_list_head, swap);
+        }
+
+        r = 0;
+
+finish:
+        fclose(proc_swaps);
+
+        return r;
+}
+
+static int loopback_list_get(MountPoint **loopback_list_head) {
+        int r;
+        struct udev *udev;
+        struct udev_enumerate *e = NULL;
+        struct udev_list_entry *item = NULL, *first = NULL;
+
+        if (!(udev = udev_new())) {
+                r = -ENOMEM;
+                goto finish;
+        }
+
+        if (!(e = udev_enumerate_new(udev))) {
+                r = -ENOMEM;
+                goto finish;
+        }
+
+        if (udev_enumerate_add_match_subsystem(e, "block") < 0) {
+                r = -EIO;
+                goto finish;
+        }
+
+        if (udev_enumerate_add_match_sysname(e, "loop*") < 0) {
+                r = -EIO;
+                goto finish;
+        }
+
+        if (udev_enumerate_scan_devices(e) < 0) {
+                r = -EIO;
+                goto finish;
+        }
+
+        first = udev_enumerate_get_list_entry(e);
+
+        udev_list_entry_foreach(item, first) {
+                MountPoint *lb;
+                char *loop;
+
+                loop = cunescape(udev_list_entry_get_name(item));
+                if (!loop) {
+                        r = -ENOMEM;
+                        goto finish;
+                }
+
+                lb = mount_point_alloc(loop);
+                if (!lb) {
+                        free(loop);
+                        r = -ENOMEM;
+                        goto finish;
+                }
+
+                LIST_PREPEND(MountPoint, mount_point, *loopback_list_head, lb);
+        }
+
+        r = 0;
+
+finish:
+        if (e)
+                udev_enumerate_unref(e);
+
+        free(udev);
+        return r;
+}
+
+static int delete_loopback(const char *device) {
+        int fd, r;
+
+        if ((fd = open(device, O_RDONLY|O_CLOEXEC)) < 0) {
+                if (errno == ENOENT) {
+                        log_debug("Loop device %s does not exist.", device);
+                        errno = 0;
+                        return 0;
+                }
+                return -errno;
+        }
+
+        ioctl(fd, LOOP_CLR_FD, 0);
+        r = errno;
+        close_nointr(fd);
+
+        if (r == ENXIO) /* not bound, so no error */
+                r = 0;
+        errno = r;
+        return -errno;
+}
+
+static int mount_points_list_umount(MountPoint **mount_point_list_head) {
+        MountPoint *mp, *mp_next;
+        int failed = 0;
+
+        LIST_FOREACH_SAFE(mount_point, mp, mp_next, *mount_point_list_head) {
+                if (streq(mp->path, "/"))
+                        continue;
+
+                /* Trying to umount. Forcing to umount if busy (only for NFS mounts) */
+                if (umount2(mp->path, MNT_FORCE) == 0)
+                        mount_point_remove_and_free(mp, mount_point_list_head);
+                else {
+                        log_debug("Could not unmount %s: %m", mp->path);
+                        failed++;
+                }
+        }
+
+        return failed;
+}
+
+static int mount_points_list_remount_read_only(MountPoint **mount_point_list_head) {
+        MountPoint *mp, *mp_next;
+        int failed = 0;
+
+        LIST_FOREACH_SAFE(mount_point, mp, mp_next, *mount_point_list_head) {
+                if (mp->read_only)
+                        continue;
+
+                /* Trying to remount read-only */
+                if (mount(NULL, mp->path, NULL, MS_MGC_VAL|MS_REMOUNT|MS_RDONLY, NULL) == 0) {
+                        mp->read_only = true;
+                        mount_point_remove_and_free(mp, mount_point_list_head);
+                } else {
+                        log_debug("Could not remount as read-only %s: %m", mp->path);
+                        failed++;
+                }
+        }
+
+        return failed;
+}
+
+static int swap_points_list_off(MountPoint **swap_list_head) {
+        MountPoint *swap, *swap_next;
+        int failed = 0;
+
+        LIST_FOREACH_SAFE(mount_point, swap, swap_next, *swap_list_head) {
+                if (swapoff(swap->path) == 0)
+                        mount_point_remove_and_free(swap, swap_list_head);
+                else {
+                        log_debug("Could not swapoff %s: %m", swap->path);
+                        failed++;
+                }
+        }
+
+        return failed;
+}
+
+static int loopback_points_list_detach(MountPoint **loopback_list_head) {
+        MountPoint *loopback, *loopback_next;
+        int failed = 0;
+
+        LIST_FOREACH_SAFE(mount_point, loopback, loopback_next, *loopback_list_head) {
+                if (delete_loopback(loopback->path) == 0)
+                        mount_point_remove_and_free(loopback, loopback_list_head);
+                else {
+                        log_debug("Could not delete loopback %s: %m", loopback->path);
+                        failed++;
+                }
+        }
+
+        return failed;
+}
+
+int umount_all(void) {
+        int r;
+        LIST_HEAD(MountPoint, mp_list_head);
+
+        LIST_HEAD_INIT(MountPoint, mp_list_head);
+
+        r = mount_points_list_get(&mp_list_head);
+        if (r < 0)
+                goto end;
+
+        r = mount_points_list_umount(&mp_list_head);
+        if (r <= 0)
+                goto end;
+
+        r = mount_points_list_remount_read_only(&mp_list_head);
+
+  end:
+        mount_points_list_free(&mp_list_head);
+
+        return r;
+}
+
+int swapoff_all(void) {
+        int r;
+        LIST_HEAD(MountPoint, swap_list_head);
+
+        LIST_HEAD_INIT(MountPoint, swap_list_head);
+
+        r = swap_list_get(&swap_list_head);
+        if (r < 0)
+                goto end;
+
+        r = swap_points_list_off(&swap_list_head);
+
+  end:
+        mount_points_list_free(&swap_list_head);
+
+        return r;
+}
+
+int loopback_detach_all(void) {
+        int r;
+        LIST_HEAD(MountPoint, loopback_list_head);
+
+        LIST_HEAD_INIT(MountPoint, loopback_list_head);
+
+        r = loopback_list_get(&loopback_list_head);
+        if (r < 0)
+                goto end;
+
+        r = loopback_points_list_detach(&loopback_list_head);
+
+  end:
+        mount_points_list_free(&loopback_list_head);
+
+        return r;
+}
diff --git a/src/umount.h b/src/umount.h
new file mode 100644
index 0000000000..aeccc00f1e
--- /dev/null
+++ b/src/umount.h
@@ -0,0 +1,31 @@
+/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
+
+#ifndef fooumounthfoo
+#define fooumounthfoo
+
+/***
+  This file is part of systemd.
+
+  Copyright 2010 ProFUSION embedded systems
+
+  systemd is free software; you can redistribute it and/or modify it
+  under the terms of the GNU General Public License as published by
+  the Free Software Foundation; either version 2 of the License, or
+  (at your option) any later version.
+
+  systemd is distributed in the hope that it will be useful, but
+  WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+  General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with systemd; If not, see <http://www.gnu.org/licenses/>.
+***/
+
+int umount_all(void);
+
+int swapoff_all(void);
+
+int loopback_detach_all(void);
+
+#endif