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Systemd/src/core/umount.c

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/*-*- 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 Lesser General Public License as published by
the Free Software Foundation; either version 2.1 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
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser 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 <linux/dm-ioctl.h>
#include <libudev.h>
#include "list.h"
#include "mount-setup.h"
#include "umount.h"
#include "path-util.h"
#include "util.h"
#include "virt.h"
typedef struct MountPoint {
char *path;
dev_t devnum;
LIST_FIELDS (struct MountPoint, mount_point);
} MountPoint;
static void mount_point_free(MountPoint **head, MountPoint *m) {
assert(head);
assert(m);
LIST_REMOVE(MountPoint, mount_point, *head, m);
free(m->path);
free(m);
}
static void mount_points_list_free(MountPoint **head) {
assert(head);
while (*head)
mount_point_free(head, *head);
}
static int mount_points_list_get(MountPoint **head) {
FILE *proc_self_mountinfo;
char *path, *p;
unsigned int i;
int r;
assert(head);
if (!(proc_self_mountinfo = fopen("/proc/self/mountinfo", "re")))
return -errno;
for (i = 1;; i++) {
int k;
MountPoint *m;
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;
}
p = cunescape(path);
free(path);
if (!p) {
r = -ENOMEM;
goto finish;
}
/* Ignore mount points we can't unmount because they
* are API or because we are keeping them open (like
* /dev/console) */
if (mount_point_is_api(p) ||
mount_point_ignore(p) ||
path_equal(p, "/dev/console")) {
free(p);
continue;
}
if (!(m = new0(MountPoint, 1))) {
free(p);
r = -ENOMEM;
goto finish;
}
m->path = p;
LIST_PREPEND(MountPoint, mount_point, *head, m);
}
r = 0;
finish:
fclose(proc_self_mountinfo);
return r;
}
static int swap_list_get(MountPoint **head) {
FILE *proc_swaps;
unsigned int i;
int r;
assert(head);
if (!(proc_swaps = fopen("/proc/swaps", "re")))
return (errno == ENOENT) ? 0 : -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;
}
if (!(swap = new0(MountPoint, 1))) {
free(d);
r = -ENOMEM;
goto finish;
}
swap->path = d;
LIST_PREPEND(MountPoint, mount_point, *head, swap);
}
r = 0;
finish:
fclose(proc_swaps);
return r;
}
static int loopback_list_get(MountPoint **head) {
int r;
struct udev *udev;
struct udev_enumerate *e = NULL;
struct udev_list_entry *item = NULL, *first = NULL;
assert(head);
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 ||
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;
struct udev_device *d;
char *loop;
const char *dn;
if (!(d = udev_device_new_from_syspath(udev, udev_list_entry_get_name(item)))) {
r = -ENOMEM;
goto finish;
}
if (!(dn = udev_device_get_devnode(d))) {
udev_device_unref(d);
continue;
}
loop = strdup(dn);
udev_device_unref(d);
if (!loop) {
r = -ENOMEM;
goto finish;
}
if (!(lb = new0(MountPoint, 1))) {
free(loop);
r = -ENOMEM;
goto finish;
}
lb->path = loop;
LIST_PREPEND(MountPoint, mount_point, *head, lb);
}
r = 0;
finish:
if (e)
udev_enumerate_unref(e);
if (udev)
udev_unref(udev);
return r;
}
static int dm_list_get(MountPoint **head) {
int r;
struct udev *udev;
struct udev_enumerate *e = NULL;
struct udev_list_entry *item = NULL, *first = NULL;
assert(head);
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 ||
udev_enumerate_add_match_sysname(e, "dm-*") < 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 *m;
struct udev_device *d;
dev_t devnum;
char *node;
const char *dn;
if (!(d = udev_device_new_from_syspath(udev, udev_list_entry_get_name(item)))) {
r = -ENOMEM;
goto finish;
}
devnum = udev_device_get_devnum(d);
dn = udev_device_get_devnode(d);
if (major(devnum) == 0 || !dn) {
udev_device_unref(d);
continue;
}
node = strdup(dn);
udev_device_unref(d);
if (!node) {
r = -ENOMEM;
goto finish;
}
if (!(m = new(MountPoint, 1))) {
free(node);
r = -ENOMEM;
goto finish;
}
m->path = node;
m->devnum = devnum;
LIST_PREPEND(MountPoint, mount_point, *head, m);
}
r = 0;
finish:
if (e)
udev_enumerate_unref(e);
if (udev)
udev_unref(udev);
return r;
}
static int delete_loopback(const char *device) {
int fd, r;
if ((fd = open(device, O_RDONLY|O_CLOEXEC)) < 0)
return errno == ENOENT ? 0 : -errno;
r = ioctl(fd, LOOP_CLR_FD, 0);
close_nointr_nofail(fd);
if (r >= 0)
return 1;
/* ENXIO: not bound, so no error */
if (errno == ENXIO)
return 0;
return -errno;
}
static int delete_dm(dev_t devnum) {
int fd, r;
struct dm_ioctl dm;
assert(major(devnum) != 0);
if ((fd = open("/dev/mapper/control", O_RDWR|O_CLOEXEC)) < 0)
return -errno;
zero(dm);
dm.version[0] = DM_VERSION_MAJOR;
dm.version[1] = DM_VERSION_MINOR;
dm.version[2] = DM_VERSION_PATCHLEVEL;
dm.data_size = sizeof(dm);
dm.dev = devnum;
r = ioctl(fd, DM_DEV_REMOVE, &dm);
close_nointr_nofail(fd);
return r >= 0 ? 0 : -errno;
}
static int mount_points_list_umount(MountPoint **head, bool *changed, bool log_error) {
MountPoint *m, *n;
int n_failed = 0;
assert(head);
LIST_FOREACH_SAFE(mount_point, m, n, *head) {
/* If we are in a container, don't attempt to
read-only mount anything as that brings no real
benefits, but might confuse the host, as we remount
the superblock here, not the bind mound. */
if (detect_container(NULL) <= 0) {
/* We always try to remount directories
* read-only first, before we go on and umount
* them.
*
* Mount points can be stacked. If a mount
* point is stacked below / or /usr, we
* cannnot umount or remount it directly,
* since there is no way to refer to the
* underlying mount. There's nothing we can do
* about it for the general case, but we can
* do something about it if it is aliased
* somehwere else via a bind mount. If we
* explicitly remount the super block of that
* alias read-only we hence should be
* relatively safe regarding keeping the fs we
* can otherwise not see dirty. */
mount(NULL, m->path, NULL, MS_REMOUNT|MS_RDONLY, NULL);
}
/* Skip / and /usr since we cannot unmount that
* anyway, since we are running from it. They have
* already been remounted ro. */
if (path_equal(m->path, "/")
#ifndef HAVE_SPLIT_USR
|| path_equal(m->path, "/usr")
#endif
)
continue;
/* Trying to umount. Forcing to umount if busy (only for NFS mounts) */
log_info("Unmounting %s.", m->path);
if (umount2(m->path, MNT_FORCE) == 0) {
if (changed)
*changed = true;
mount_point_free(head, m);
} else if (log_error) {
log_warning("Could not unmount %s: %m", m->path);
n_failed++;
}
}
return n_failed;
}
static int swap_points_list_off(MountPoint **head, bool *changed) {
MountPoint *m, *n;
int n_failed = 0;
assert(head);
LIST_FOREACH_SAFE(mount_point, m, n, *head) {
log_info("Deactivating swap %s.", m->path);
if (swapoff(m->path) == 0) {
if (changed)
*changed = true;
mount_point_free(head, m);
} else {
log_warning("Could not deactivate swap %s: %m", m->path);
n_failed++;
}
}
return n_failed;
}
static int loopback_points_list_detach(MountPoint **head, bool *changed) {
MountPoint *m, *n;
int n_failed = 0, k;
struct stat root_st;
assert(head);
k = lstat("/", &root_st);
LIST_FOREACH_SAFE(mount_point, m, n, *head) {
int r;
struct stat loopback_st;
if (k >= 0 &&
major(root_st.st_dev) != 0 &&
lstat(m->path, &loopback_st) >= 0 &&
root_st.st_dev == loopback_st.st_rdev) {
n_failed ++;
continue;
}
log_info("Detaching loopback %s.", m->path);
r = delete_loopback(m->path);
if (r >= 0) {
if (r > 0 && changed)
*changed = true;
mount_point_free(head, m);
} else {
log_warning("Could not detach loopback %s: %m", m->path);
n_failed++;
}
}
return n_failed;
}
static int dm_points_list_detach(MountPoint **head, bool *changed) {
MountPoint *m, *n;
int n_failed = 0, k;
struct stat root_st;
assert(head);
k = lstat("/", &root_st);
LIST_FOREACH_SAFE(mount_point, m, n, *head) {
int r;
if (k >= 0 &&
major(root_st.st_dev) != 0 &&
root_st.st_dev == m->devnum) {
n_failed ++;
continue;
}
log_info("Detaching DM %u:%u.", major(m->devnum), minor(m->devnum));
r = delete_dm(m->devnum);
if (r >= 0) {
if (changed)
*changed = true;
mount_point_free(head, m);
} else {
log_warning("Could not detach DM %s: %m", m->path);
n_failed++;
}
}
return n_failed;
}
int umount_all(bool *changed) {
int r;
bool umount_changed;
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;
/* retry umount, until nothing can be umounted anymore */
do {
umount_changed = false;
mount_points_list_umount(&mp_list_head, &umount_changed, false);
if (umount_changed)
*changed = true;
} while (umount_changed);
/* umount one more time with logging enabled */
r = mount_points_list_umount(&mp_list_head, &umount_changed, true);
if (r <= 0)
goto end;
end:
mount_points_list_free(&mp_list_head);
return r;
}
int swapoff_all(bool *changed) {
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, changed);
end:
mount_points_list_free(&swap_list_head);
return r;
}
int loopback_detach_all(bool *changed) {
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, changed);
end:
mount_points_list_free(&loopback_list_head);
return r;
}
int dm_detach_all(bool *changed) {
int r;
LIST_HEAD(MountPoint, dm_list_head);
LIST_HEAD_INIT(MountPoint, dm_list_head);
r = dm_list_get(&dm_list_head);
if (r < 0)
goto end;
r = dm_points_list_detach(&dm_list_head, changed);
end:
mount_points_list_free(&dm_list_head);
return r;
}
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