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mnt: In umount_tree reuse mnt_list instead of mnt_hash

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umount_tree builds a list of mounts that need to be unmounted.
Utilize mnt_list for this purpose instead of mnt_hash.  This begins to
allow keeping a mount on the mnt_hash after it is unmounted, which is
necessary for a properly functioning MNT_LOCKED implementation.

The fact that mnt_list is an ordinary list makding available list_move
is nice bonus.

Cc: stable@vger.kernel.org
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
This commit is contained in:
Eric W. Biederman
2014-12-18 13:10:48 -06:00
parent 8318e667f1
commit c003b26ff9
3 changed files with 15 additions and 13 deletions
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20
fs/namespace.c
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@@ -1327,23 +1327,25 @@ enum umount_tree_flags {
*/
static void umount_tree(struct mount *mnt, enum umount_tree_flags how)
{
HLIST_HEAD(tmp_list);
LIST_HEAD(tmp_list);
struct mount *p;
for (p = mnt; p; p = next_mnt(p, mnt)) {
/* Gather the mounts to umount */
for (p = mnt; p; p = next_mnt(p, mnt))
list_move(&p->mnt_list, &tmp_list);
/* Hide the mounts from lookup_mnt and mnt_mounts */
list_for_each_entry(p, &tmp_list, mnt_list) {
hlist_del_init_rcu(&p->mnt_hash);
hlist_add_head(&p->mnt_hash, &tmp_list);
list_del_init(&p->mnt_child);
}
hlist_for_each_entry(p, &tmp_list, mnt_hash)
list_del_init(&p->mnt_child);
/* Add propogated mounts to the tmp_list */
if (how & UMOUNT_PROPAGATE)
propagate_umount(&tmp_list);
while (!hlist_empty(&tmp_list)) {
p = hlist_entry(tmp_list.first, struct mount, mnt_hash);
hlist_del_init_rcu(&p->mnt_hash);
while (!list_empty(&tmp_list)) {
p = list_first_entry(&tmp_list, struct mount, mnt_list);
list_del_init(&p->mnt_expire);
list_del_init(&p->mnt_list);
__touch_mnt_namespace(p->mnt_ns);