/**
* 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 && mnt_context_mtab_writable(cxt))
rc = mnt_update_set_fs(cxt->update,
cxt->mountflags, NULL, cxt->fs);
}
}
return rc;
}
/**
* mnt_context_find_umount_fs:
* @cxt: mount context
* @tgt: mountpoint, device, ...
* @pfs: returns point to filesystem
*
* Returns: 0 on success, <0 on error, 1 if target filesystem not found
*/
int mnt_context_find_umount_fs(struct libmnt_context *cxt,
const char *tgt,
struct libmnt_fs **pfs)
{
int rc;
struct libmnt_table *mtab = NULL;
struct libmnt_fs *fs;
char *loopdev = NULL;
if (pfs)
*pfs = NULL;
if (!cxt || !tgt || !pfs)
return -EINVAL;
DBG(CXT, ul_debugobj(cxt, "umount: lookup FS for '%s'", tgt));
if (!*tgt)
return 1; /* empty string is not an error */
/*
* The mount table may be huge, and on systems with utab we have to merge
* userspace mount options into /proc/self/mountinfo. This all is
* expensive. The tab filter allows to filter out entries, then
* a mount table and utab are very tiny files.
*
* *but*... the filter uses mnt_fs_streq_{target,srcpath} functions
* where LABEL, UUID or symlinks are canonicalized. It means that
* it's usable only for canonicalized stuff (e.g. kernel mountinfo).
*/
if (!mnt_context_mtab_writable(cxt) && *tgt == '/' &&
!mnt_context_is_force(cxt) && !mnt_context_is_lazy(cxt))
rc = mnt_context_get_mtab_for_target(cxt, &mtab, tgt);
else
rc = mnt_context_get_mtab(cxt, &mtab);
if (rc) {
DBG(CXT, ul_debugobj(cxt, "umount: failed to read mtab"));
return rc;
}
if (mnt_table_get_nents(mtab) == 0) {
DBG(CXT, ul_debugobj(cxt, "umount: mtab empty"));
return 1;
}
try_loopdev:
fs = mnt_table_find_target(mtab, tgt, MNT_ITER_BACKWARD);
if (!fs && mnt_context_is_swapmatch(cxt)) {
/*
* Maybe the option is source rather than target (sometimes
* people use e.g. "umount /dev/sda1")
*/
fs = mnt_table_find_source(mtab, tgt, MNT_ITER_BACKWARD);
if (fs) {
struct libmnt_fs *fs1 = mnt_table_find_target(mtab,
mnt_fs_get_target(fs),
MNT_ITER_BACKWARD);
if (!fs1) {
DBG(CXT, ul_debugobj(cxt, "mtab is broken?!?!"));
rc = -EINVAL;
goto err;
}
if (fs != fs1) {
/* Something was stacked over `file' on the
* same mount point. */
DBG(CXT, ul_debugobj(cxt,
"umount: %s: %s is mounted "
"over it on the same point",
tgt, mnt_fs_get_source(fs1)));
rc = -EINVAL;
goto err;
}
}
}
if (!fs && !loopdev && mnt_context_is_swapmatch(cxt)) {
/*
* Maybe the option is /path/file.img, try to convert to /dev/loopN
*/
struct stat st;
if (mnt_stat_mountpoint(tgt, &st) == 0 && S_ISREG(st.st_mode)) {
int count;
struct libmnt_cache *cache = mnt_context_get_cache(cxt);
const char *bf = cache ? mnt_resolve_path(tgt, cache) : tgt;
count = loopdev_count_by_backing_file(bf, &loopdev);
if (count == 1) {
DBG(CXT, ul_debugobj(cxt,
"umount: %s --> %s (retry)", tgt, loopdev));
tgt = loopdev;
goto try_loopdev;
} else if (count > 1)
DBG(CXT, ul_debugobj(cxt,
"umount: warning: %s is associated "
"with more than one loopdev", tgt));
}
}
if (pfs)
*pfs = fs;
free(loopdev);
DBG(CXT, ul_debugobj(cxt, "umount fs: %s", fs ? mnt_fs_get_target(fs) :
"<not found>"));
return fs ? 0 : 1;
err:
free(loopdev);
return rc;
}
int mnt_context_setup_loopdev(struct libmnt_context *cxt)
{
const char *backing_file, *optstr, *loopdev = NULL;
char *val = NULL, *loopval = NULL;
size_t len;
struct loopdev_cxt lc;
int rc = 0, lo_flags = 0;
uint64_t offset = 0, sizelimit = 0;
assert(cxt);
assert(cxt->fs);
assert((cxt->flags & MNT_FL_MOUNTFLAGS_MERGED));
backing_file = mnt_fs_get_srcpath(cxt->fs);
if (!backing_file)
return -EINVAL;
DBG(LOOP, ul_debugobj(cxt, "trying to setup device for %s", backing_file));
if (cxt->mountflags & MS_RDONLY) {
DBG(LOOP, ul_debugobj(cxt, "enabling READ-ONLY flag"));
lo_flags |= LO_FLAGS_READ_ONLY;
}
optstr = mnt_fs_get_user_options(cxt->fs);
/*
* loop=
*/
if (rc == 0 && (cxt->user_mountflags & MNT_MS_LOOP) &&
mnt_optstr_get_option(optstr, "loop", &val, &len) == 0 && val) {
loopval = strndup(val, len);
rc = loopval ? 0 : -ENOMEM;
}
/*
* offset=
*/
if (rc == 0 && (cxt->user_mountflags & MNT_MS_OFFSET) &&
mnt_optstr_get_option(optstr, "offset", &val, &len) == 0) {
rc = mnt_parse_offset(val, len, &offset);
if (rc) {
DBG(LOOP, ul_debugobj(cxt, "failed to parse offset="));
rc = -MNT_ERR_MOUNTOPT;
}
}
/*
* sizelimit=
*/
if (rc == 0 && (cxt->user_mountflags & MNT_MS_SIZELIMIT) &&
mnt_optstr_get_option(optstr, "sizelimit", &val, &len) == 0) {
rc = mnt_parse_offset(val, len, &sizelimit);
if (rc) {
DBG(LOOP, ul_debugobj(cxt, "failed to parse sizelimit="));
rc = -MNT_ERR_MOUNTOPT;
}
}
/*
* encryption=
*/
if (rc == 0 && (cxt->user_mountflags & MNT_MS_ENCRYPTION) &&
mnt_optstr_get_option(optstr, "encryption", &val, &len) == 0) {
DBG(LOOP, ul_debugobj(cxt, "encryption no longer supported"));
rc = -MNT_ERR_MOUNTOPT;
}
if (rc == 0 && is_mounted_same_loopfile(cxt,
mnt_context_get_target(cxt),
backing_file, offset))
rc = -EBUSY;
if (rc)
goto done_no_deinit;
/* It is possible to mount the same file more times. If we set more
* than one loop device referring to the same file, kernel has no
* mechanism to detect it. To prevent data corruption, the same loop
* device has to be recycled.
*/
if (backing_file) {
rc = loopcxt_init(&lc, 0);
if (rc)
goto done_no_deinit;
rc = loopcxt_find_overlap(&lc, backing_file, offset, sizelimit);
switch (rc) {
case 0: /* not found */
DBG(LOOP, ul_debugobj(cxt, "not found overlaping loopdev"));
loopcxt_deinit(&lc);
break;
case 1: /* overlap */
DBG(LOOP, ul_debugobj(cxt, "overlaping %s detected",
loopcxt_get_device(&lc)));
rc = -MNT_ERR_LOOPOVERLAP;
goto done;
case 2: /* overlap -- full size and offset match (reuse) */
{
uint32_t lc_encrypt_type;
DBG(LOOP, ul_debugobj(cxt, "re-using existing loop device %s",
loopcxt_get_device(&lc)));
/* Once a loop is initialized RO, there is no
* way to change its parameters. */
if (loopcxt_is_readonly(&lc)
&& !(lo_flags & LO_FLAGS_READ_ONLY)) {
DBG(LOOP, ul_debugobj(cxt, "%s is read-only",
loopcxt_get_device(&lc)));
rc = -EROFS;
goto done;
}
/* This is no more supported, but check to be safe. */
if (loopcxt_get_encrypt_type(&lc, &lc_encrypt_type) == 0
&& lc_encrypt_type != LO_CRYPT_NONE) {
DBG(LOOP, ul_debugobj(cxt, "encryption no longer supported for device %s",
loopcxt_get_device(&lc)));
rc = -MNT_ERR_LOOPOVERLAP;
goto done;
}
rc = 0;
goto success;
}
default: /* error */
goto done;
}
}
DBG(LOOP, ul_debugobj(cxt, "not found; create a new loop device"));
rc = loopcxt_init(&lc, 0);
if (rc)
goto done_no_deinit;
if (loopval) {
rc = loopcxt_set_device(&lc, loopval);
if (rc == 0)
loopdev = loopcxt_get_device(&lc);
}
if (rc)
goto done;
/* since 2.6.37 we don't have to store backing filename to mtab
* because kernel provides the name in /sys.
*/
if (get_linux_version() >= KERNEL_VERSION(2, 6, 37) ||
!mnt_context_mtab_writable(cxt)) {
DBG(LOOP, ul_debugobj(cxt, "enabling AUTOCLEAR flag"));
lo_flags |= LO_FLAGS_AUTOCLEAR;
}
do {
/* found free device */
if (!loopdev) {
rc = loopcxt_find_unused(&lc);
if (rc)
goto done;
DBG(LOOP, ul_debugobj(cxt, "trying to use %s",
loopcxt_get_device(&lc)));
}
/* set device attributes
* -- note that loopcxt_find_unused() resets "lc"
*/
rc = loopcxt_set_backing_file(&lc, backing_file);
if (!rc && offset)
rc = loopcxt_set_offset(&lc, offset);
if (!rc && sizelimit)
rc = loopcxt_set_sizelimit(&lc, sizelimit);
if (!rc)
loopcxt_set_flags(&lc, lo_flags);
if (rc) {
DBG(LOOP, ul_debugobj(cxt, "failed to set loop attributes"));
goto done;
}
/* setup the device */
rc = loopcxt_setup_device(&lc);
if (!rc)
break; /* success */
if (loopdev || rc != -EBUSY) {
DBG(LOOP, ul_debugobj(cxt, "failed to setup device"));
rc = -MNT_ERR_LOOPDEV;
goto done;
}
DBG(LOOP, ul_debugobj(cxt, "device stolen...trying again"));
} while (1);
success:
if (!rc)
rc = mnt_fs_set_source(cxt->fs, loopcxt_get_device(&lc));
if (!rc) {
/* success */
cxt->flags |= MNT_FL_LOOPDEV_READY;
if ((cxt->user_mountflags & MNT_MS_LOOP) &&
loopcxt_is_autoclear(&lc)) {
/*
* autoclear flag accepted by the kernel, don't store
* the "loop=" option to mtab.
*/
DBG(LOOP, ul_debugobj(cxt, "removing unnecessary loop= from mtab"));
cxt->user_mountflags &= ~MNT_MS_LOOP;
mnt_optstr_remove_option(&cxt->fs->user_optstr, "loop");
}
if (!(cxt->mountflags & MS_RDONLY) &&
loopcxt_is_readonly(&lc))
/*
* mount planned read-write, but loopdev is read-only,
* let's fix mount options...
*/
mnt_context_set_mflags(cxt, cxt->mountflags | MS_RDONLY);
/* we have to keep the device open until mount(1),
* otherwise it will be auto-cleared by kernel
*/
cxt->loopdev_fd = loopcxt_get_fd(&lc);
if (cxt->loopdev_fd < 0) {
DBG(LOOP, ul_debugobj(cxt, "failed to get loopdev FD"));
rc = -errno;
} else
loopcxt_set_fd(&lc, -1, 0);
}
done:
loopcxt_deinit(&lc);
done_no_deinit:
free(loopval);
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;
}
int mnt_context_setup_loopdev(struct libmnt_context *cxt)
{
const char *backing_file, *optstr, *loopdev = NULL;
char *val = NULL;
size_t len;
struct loopdev_cxt lc;
int rc = 0, lo_flags = 0;
uint64_t offset = 0, sizelimit = 0;
assert(cxt->fs);
assert((cxt->flags & MNT_FL_MOUNTFLAGS_MERGED));
if (!cxt)
return -EINVAL;
backing_file = mnt_fs_get_srcpath(cxt->fs);
if (!backing_file)
return -EINVAL;
DBG(CXT, ul_debugobj(cxt, "trying to setup loopdev for %s", backing_file));
if (cxt->mountflags & MS_RDONLY) {
DBG(CXT, ul_debugobj(cxt, "enabling READ-ONLY flag"));
lo_flags |= LO_FLAGS_READ_ONLY;
}
rc = loopcxt_init(&lc, 0);
if (rc)
return rc;
ON_DBG(CXT, loopcxt_enable_debug(&lc, 1));
optstr = mnt_fs_get_user_options(cxt->fs);
/*
* loop=
*/
if (rc == 0 && (cxt->user_mountflags & MNT_MS_LOOP) &&
mnt_optstr_get_option(optstr, "loop", &val, &len) == 0 && val) {
val = strndup(val, len);
rc = val ? loopcxt_set_device(&lc, val) : -ENOMEM;
free(val);
if (rc == 0)
loopdev = loopcxt_get_device(&lc);
}
/*
* offset=
*/
if (rc == 0 && (cxt->user_mountflags & MNT_MS_OFFSET) &&
mnt_optstr_get_option(optstr, "offset", &val, &len) == 0) {
rc = mnt_parse_offset(val, len, &offset);
if (rc) {
DBG(CXT, ul_debugobj(cxt, "failed to parse offset="));
rc = -MNT_ERR_MOUNTOPT;
}
}
/*
* sizelimit=
*/
if (rc == 0 && (cxt->user_mountflags & MNT_MS_SIZELIMIT) &&
mnt_optstr_get_option(optstr, "sizelimit", &val, &len) == 0) {
rc = mnt_parse_offset(val, len, &sizelimit);
if (rc) {
DBG(CXT, ul_debugobj(cxt, "failed to parse sizelimit="));
rc = -MNT_ERR_MOUNTOPT;
}
}
/*
* encryption=
*/
if (rc == 0 && (cxt->user_mountflags & MNT_MS_ENCRYPTION) &&
mnt_optstr_get_option(optstr, "encryption", &val, &len) == 0) {
DBG(CXT, ul_debugobj(cxt, "encryption no longer supported"));
rc = -MNT_ERR_MOUNTOPT;
}
if (rc == 0 && is_mounted_same_loopfile(cxt,
mnt_context_get_target(cxt),
backing_file, offset))
rc = -EBUSY;
if (rc)
goto done;
/* since 2.6.37 we don't have to store backing filename to mtab
* because kernel provides the name in /sys.
*/
if (get_linux_version() >= KERNEL_VERSION(2, 6, 37) ||
!mnt_context_mtab_writable(cxt)) {
DBG(CXT, ul_debugobj(cxt, "enabling AUTOCLEAR flag"));
lo_flags |= LO_FLAGS_AUTOCLEAR;
}
do {
/* found free device */
if (!loopdev) {
rc = loopcxt_find_unused(&lc);
if (rc)
goto done;
DBG(CXT, ul_debugobj(cxt, "trying to use %s",
loopcxt_get_device(&lc)));
}
/* set device attributes
* -- note that loopcxt_find_unused() resets "lc"
*/
rc = loopcxt_set_backing_file(&lc, backing_file);
if (!rc && offset)
rc = loopcxt_set_offset(&lc, offset);
if (!rc && sizelimit)
rc = loopcxt_set_sizelimit(&lc, sizelimit);
if (!rc)
loopcxt_set_flags(&lc, lo_flags);
if (rc) {
DBG(CXT, ul_debugobj(cxt, "failed to set loopdev attributes"));
goto done;
}
/* setup the device */
rc = loopcxt_setup_device(&lc);
if (!rc)
break; /* success */
if (loopdev || rc != -EBUSY) {
DBG(CXT, ul_debugobj(cxt, "failed to setup device"));
rc = -MNT_ERR_LOOPDEV;
goto done;
}
DBG(CXT, ul_debugobj(cxt, "loopdev stolen...trying again"));
} while (1);
if (!rc)
rc = mnt_fs_set_source(cxt->fs, loopcxt_get_device(&lc));
if (!rc) {
/* success */
cxt->flags |= MNT_FL_LOOPDEV_READY;
if ((cxt->user_mountflags & MNT_MS_LOOP) &&
loopcxt_is_autoclear(&lc)) {
/*
* autoclear flag accepted by the kernel, don't store
* the "loop=" option to mtab.
*/
cxt->user_mountflags &= ~MNT_MS_LOOP;
mnt_optstr_remove_option(&cxt->fs->user_optstr, "loop");
}
if (!(cxt->mountflags & MS_RDONLY) &&
loopcxt_is_readonly(&lc))
/*
* mount planned read-write, but loopdev is read-only,
* let's fix mount options...
*/
mnt_context_set_mflags(cxt, cxt->mountflags | MS_RDONLY);
/* we have to keep the device open until mount(1),
* otherwise it will be auto-cleared by kernel
*/
cxt->loopdev_fd = loopcxt_get_fd(&lc);
loopcxt_set_fd(&lc, -1, 0);
}
done:
loopcxt_deinit(&lc);
return rc;
}
