/**
* mnt_context_prepare_umount:
* @cxt: mount context
*
* Prepare context for umounting, unnecessary for mnt_context_umount().
*
* Returns: 0 on success, and negative number in case of error.
*/
int mnt_context_prepare_umount(struct libmnt_context *cxt)
{
int rc;
assert(cxt);
assert(cxt->fs);
assert(cxt->helper_exec_status == 1);
assert(cxt->syscall_status == 1);
if (!cxt || !cxt->fs || mnt_fs_is_swaparea(cxt->fs))
return -EINVAL;
if (!mnt_context_get_source(cxt) && !mnt_context_get_target(cxt))
return -EINVAL;
if (cxt->flags & MNT_FL_PREPARED)
return 0;
free(cxt->helper); /* be paranoid */
cxt->helper = NULL;
cxt->action = MNT_ACT_UMOUNT;
rc = lookup_umount_fs(cxt);
if (!rc)
rc = mnt_context_merge_mflags(cxt);
if (!rc)
rc = evaluate_permissions(cxt);
if (!rc && !cxt->helper) {
if (cxt->user_mountflags & MNT_MS_HELPER)
/* on helper= mount option based helper */
rc = prepare_helper_from_options(cxt, "helper");
if (!rc && !cxt->helper)
/* on fstype based helper */
rc = mnt_context_prepare_helper(cxt, "umount", NULL);
}
if (!rc && (cxt->user_mountflags & MNT_MS_LOOP))
/* loop option explicitly specified in mtab, detach this loop */
mnt_context_enable_loopdel(cxt, TRUE);
if (!rc && mnt_context_is_loopdel(cxt) && cxt->fs) {
const char *src = mnt_fs_get_srcpath(cxt->fs);
if (src && (!is_loopdev(src) || loopdev_is_autoclear(src)))
mnt_context_enable_loopdel(cxt, FALSE);
}
if (rc) {
DBG(CXT, mnt_debug_h(cxt, "umount: preparing failed"));
return rc;
}
cxt->flags |= MNT_FL_PREPARED;
return rc;
}
/**
* mnt_context_do_umount:
* @cxt: mount context
*
* Umount filesystem by umount(2) or fork()+exec(/sbin/umount.type).
* Unnecessary for mnt_context_umount().
*
* See also mnt_context_disable_helpers().
*
* WARNING: non-zero return code does not mean that umount(2) syscall or
* umount.type helper wasn't successfully called.
*
* Check mnt_context_get_status() after error!
*
* Returns: 0 on success;
* >0 in case of umount(2) error (returns syscall errno),
* <0 in case of other errors.
*/
int mnt_context_do_umount(struct libmnt_context *cxt)
{
int rc;
assert(cxt);
assert(cxt->fs);
assert(cxt->helper_exec_status == 1);
assert(cxt->syscall_status == 1);
assert((cxt->flags & MNT_FL_PREPARED));
assert((cxt->action == MNT_ACT_UMOUNT));
assert((cxt->flags & MNT_FL_MOUNTFLAGS_MERGED));
rc = do_umount(cxt);
if (rc)
return rc;
if (mnt_context_get_status(cxt) && !mnt_context_is_fake(cxt)) {
/*
* Umounted, do some post-umount operations
* - remove loopdev
* - refresh in-memory mtab stuff if remount rather than
* umount has been performed
*/
if (mnt_context_is_loopdel(cxt)
&& !(cxt->mountflags & MS_REMOUNT))
rc = mnt_context_delete_loopdev(cxt);
if (!mnt_context_is_nomtab(cxt)
&& mnt_context_get_status(cxt)
&& !cxt->helper
&& mnt_context_is_rdonly_umount(cxt)
&& (cxt->mountflags & MS_REMOUNT)) {
/* use "remount" instead of "umount" in /etc/mtab */
if (!rc && cxt->update && cxt->mtab_writable)
rc = mnt_update_set_fs(cxt->update,
cxt->mountflags, NULL, cxt->fs);
}
}
return rc;
}
/* this is umount replacement to mnt_context_apply_fstab(), use
* mnt_context_tab_applied() to check result.
*/
static int lookup_umount_fs(struct libmnt_context *cxt)
{
const char *tgt;
struct stat st;
struct libmnt_fs *fs = NULL;
int rc = 0;
assert(cxt);
assert(cxt->fs);
tgt = mnt_fs_get_target(cxt->fs);
if (!tgt) {
DBG(CXT, ul_debugobj(cxt, "umount: undefined target"));
return -EINVAL;
}
/*
* Let's try to avoid mountinfo usage at all to minimize performance
* degradation. Don't forget that kernel has to compose *whole*
* mountinfo about all mountpoints although we look for only one entry.
*
* All we need is fstype and to check if there is no userspace mount
* options for the target (e.g. helper=udisks to call /sbin/umount.udisks).
*
* So, let's use statfs() if possible (it's bad idea for --lazy/--force
* umounts as target is probably unreachable NFS, also for --detach-loop
* as this additionally needs to know the name of the loop device).
*/
if (!mnt_context_is_restricted(cxt)
&& *tgt == '/'
&& !(cxt->flags & MNT_FL_HELPER)
&& !mnt_context_mtab_writable(cxt)
&& !mnt_context_is_force(cxt)
&& !mnt_context_is_lazy(cxt)
&& !mnt_context_is_loopdel(cxt)
&& mnt_stat_mountpoint(tgt, &st) == 0 && S_ISDIR(st.st_mode)
&& !has_utab_entry(cxt, tgt)) {
const char *type = mnt_fs_get_fstype(cxt->fs);
/* !mnt_context_mtab_writable(cxt) && has_utab_entry() verified that there
* is no stuff in utab, so disable all mtab/utab related actions */
mnt_context_disable_mtab(cxt, TRUE);
if (!type) {
struct statfs vfs;
if (statfs(tgt, &vfs) == 0)
type = mnt_statfs_get_fstype(&vfs);
if (type) {
rc = mnt_fs_set_fstype(cxt->fs, type);
if (rc)
return rc;
}
}
if (type) {
DBG(CXT, ul_debugobj(cxt,
"umount: mountinfo unnecessary [type=%s]", type));
return 0;
}
}
rc = mnt_context_find_umount_fs(cxt, tgt, &fs);
if (rc < 0)
return rc;
if (rc == 1 || !fs) {
DBG(CXT, ul_debugobj(cxt, "umount: cannot find '%s' in mtab", tgt));
return 0; /* this is correct! */
}
if (fs != cxt->fs) {
/* copy from mtab to our FS description
*/
mnt_fs_set_source(cxt->fs, NULL);
mnt_fs_set_target(cxt->fs, NULL);
if (!mnt_copy_fs(cxt->fs, fs)) {
DBG(CXT, ul_debugobj(cxt, "umount: failed to copy FS"));
return -errno;
}
DBG(CXT, ul_debugobj(cxt, "umount: mtab applied"));
}
cxt->flags |= MNT_FL_TAB_APPLIED;
return rc;
}
