1 files changed, 167 insertions, 0 deletions
diff --git a/src/shutdown/detach-dm.c b/src/shutdown/detach-dm.c
new file mode 100644
index 0000000..8b8f72d
--- /dev/null
+++ b/src/shutdown/detach-dm.c
@@ -0,0 +1,167 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+/***
+  Copyright © 2010 ProFUSION embedded systems
+***/
+
+#include <linux/dm-ioctl.h>
+#include <sys/ioctl.h>
+
+#include "sd-device.h"
+
+#include "alloc-util.h"
+#include "blockdev-util.h"
+#include "detach-dm.h"
+#include "device-util.h"
+#include "devnum-util.h"
+#include "errno-util.h"
+#include "fd-util.h"
+#include "sync-util.h"
+
+typedef struct DeviceMapper {
+        char *path;
+        dev_t devnum;
+        LIST_FIELDS(struct DeviceMapper, device_mapper);
+} DeviceMapper;
+
+static void device_mapper_free(DeviceMapper **head, DeviceMapper *m) {
+        assert(head);
+        assert(m);
+
+        LIST_REMOVE(device_mapper, *head, m);
+
+        free(m->path);
+        free(m);
+}
+
+static void device_mapper_list_free(DeviceMapper **head) {
+        assert(head);
+
+        while (*head)
+                device_mapper_free(head, *head);
+}
+
+static int dm_list_get(DeviceMapper **head) {
+        _cleanup_(sd_device_enumerator_unrefp) sd_device_enumerator *e = NULL;
+        int r;
+
+        assert(head);
+
+        r = sd_device_enumerator_new(&e);
+        if (r < 0)
+                return r;
+
+        r = sd_device_enumerator_allow_uninitialized(e);
+        if (r < 0)
+                return r;
+
+        r = sd_device_enumerator_add_match_subsystem(e, "block", true);
+        if (r < 0)
+                return r;
+
+        r = sd_device_enumerator_add_match_sysname(e, "dm-*");
+        if (r < 0)
+                return r;
+
+        FOREACH_DEVICE(e, d) {
+                _cleanup_free_ char *p = NULL;
+                const char *dn;
+                DeviceMapper *m;
+                dev_t devnum;
+
+                if (sd_device_get_devnum(d, &devnum) < 0 ||
+                    sd_device_get_devname(d, &dn) < 0)
+                        continue;
+
+                p = strdup(dn);
+                if (!p)
+                        return -ENOMEM;
+
+                m = new(DeviceMapper, 1);
+                if (!m)
+                        return -ENOMEM;
+
+                *m = (DeviceMapper) {
+                        .path = TAKE_PTR(p),
+                        .devnum = devnum,
+                };
+
+                LIST_PREPEND(device_mapper, *head, m);
+        }
+
+        return 0;
+}
+
+static int delete_dm(DeviceMapper *m) {
+        _cleanup_close_ int fd = -EBADF;
+        int r;
+
+        assert(m);
+        assert(major(m->devnum) != 0);
+        assert(m->path);
+
+        fd = open("/dev/mapper/control", O_RDWR|O_CLOEXEC);
+        if (fd < 0)
+                return -errno;
+
+        r = fsync_path_at(AT_FDCWD, m->path);
+        if (r < 0)
+                log_debug_errno(r, "Failed to sync DM block device %s, ignoring: %m", m->path);
+
+        return RET_NERRNO(ioctl(fd, DM_DEV_REMOVE, &(struct dm_ioctl) {
+                .version = {
+                        DM_VERSION_MAJOR,
+                        DM_VERSION_MINOR,
+                        DM_VERSION_PATCHLEVEL
+                },
+                .data_size = sizeof(struct dm_ioctl),
+                .dev = m->devnum,
+        }));
+}
+
+static int dm_points_list_detach(DeviceMapper **head, bool *changed, bool last_try) {
+        int n_failed = 0, r;
+        dev_t rootdev = 0, usrdev = 0;
+
+        assert(head);
+        assert(changed);
+
+        (void) get_block_device("/", &rootdev);
+        (void) get_block_device("/usr", &usrdev);
+
+        LIST_FOREACH(device_mapper, m, *head) {
+                if ((major(rootdev) != 0 && rootdev == m->devnum) ||
+                    (major(usrdev) != 0 && usrdev == m->devnum)) {
+                        log_debug("Not detaching DM %s that backs the OS itself, skipping.", m->path);
+                        n_failed ++;
+                        continue;
+                }
+
+                log_info("Detaching DM %s (" DEVNUM_FORMAT_STR ").", m->path, DEVNUM_FORMAT_VAL(m->devnum));
+                r = delete_dm(m);
+                if (r < 0) {
+                        log_full_errno(last_try ? LOG_ERR : LOG_INFO, r, "Could not detach DM %s: %m", m->path);
+                        n_failed++;
+                        continue;
+                }
+
+                *changed = true;
+                device_mapper_free(head, m);
+        }
+
+        return n_failed;
+}
+
+int dm_detach_all(bool *changed, bool last_try) {
+        _cleanup_(device_mapper_list_free) LIST_HEAD(DeviceMapper, dm_list_head);
+        int r;
+
+        assert(changed);
+
+        LIST_HEAD_INIT(dm_list_head);
+
+        r = dm_list_get(&dm_list_head);
+        if (r < 0)
+                return r;
+
+        return dm_points_list_detach(&dm_list_head, changed, last_try);
+}