get rid of ->mnt_longterm
it's enough to set ->mnt_ns of internal vfsmounts to something
distinct from all struct mnt_namespace out there; then we can
just use the check for ->mnt_ns != NULL in the fast path of
mntput_no_expire()
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/namespace.c b/fs/namespace.c
index 1e4a5fe..a524ea4 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -621,21 +621,6 @@
list_add_tail(&mnt->mnt_child, &real_mount(path->mnt)->mnt_mounts);
}
-static inline void __mnt_make_longterm(struct mount *mnt)
-{
-#ifdef CONFIG_SMP
- atomic_inc(&mnt->mnt_longterm);
-#endif
-}
-
-/* needs vfsmount lock for write */
-static inline void __mnt_make_shortterm(struct mount *mnt)
-{
-#ifdef CONFIG_SMP
- atomic_dec(&mnt->mnt_longterm);
-#endif
-}
-
/*
* vfsmount lock must be held for write
*/
@@ -649,10 +634,8 @@
BUG_ON(parent == mnt);
list_add_tail(&head, &mnt->mnt_list);
- list_for_each_entry(m, &head, mnt_list) {
+ list_for_each_entry(m, &head, mnt_list)
m->mnt_ns = n;
- __mnt_make_longterm(m);
- }
list_splice(&head, n->list.prev);
@@ -804,7 +787,8 @@
put_again:
#ifdef CONFIG_SMP
br_read_lock(&vfsmount_lock);
- if (likely(atomic_read(&mnt->mnt_longterm))) {
+ if (likely(mnt->mnt_ns)) {
+ /* shouldn't be the last one */
mnt_add_count(mnt, -1);
br_read_unlock(&vfsmount_lock);
return;
@@ -1074,8 +1058,6 @@
list_del_init(&p->mnt_expire);
list_del_init(&p->mnt_list);
__touch_mnt_namespace(p->mnt_ns);
- if (p->mnt_ns)
- __mnt_make_shortterm(p);
p->mnt_ns = NULL;
list_del_init(&p->mnt_child);
if (mnt_has_parent(p)) {
@@ -2209,23 +2191,6 @@
return new_ns;
}
-void mnt_make_longterm(struct vfsmount *mnt)
-{
- __mnt_make_longterm(real_mount(mnt));
-}
-
-void mnt_make_shortterm(struct vfsmount *m)
-{
-#ifdef CONFIG_SMP
- struct mount *mnt = real_mount(m);
- if (atomic_add_unless(&mnt->mnt_longterm, -1, 1))
- return;
- br_write_lock(&vfsmount_lock);
- atomic_dec(&mnt->mnt_longterm);
- br_write_unlock(&vfsmount_lock);
-#endif
-}
-
/*
* Allocate a new namespace structure and populate it with contents
* copied from the namespace of the passed in task structure.
@@ -2265,18 +2230,13 @@
q = new;
while (p) {
q->mnt_ns = new_ns;
- __mnt_make_longterm(q);
if (fs) {
if (&p->mnt == fs->root.mnt) {
fs->root.mnt = mntget(&q->mnt);
- __mnt_make_longterm(q);
- mnt_make_shortterm(&p->mnt);
rootmnt = &p->mnt;
}
if (&p->mnt == fs->pwd.mnt) {
fs->pwd.mnt = mntget(&q->mnt);
- __mnt_make_longterm(q);
- mnt_make_shortterm(&p->mnt);
pwdmnt = &p->mnt;
}
}
@@ -2320,7 +2280,6 @@
if (!IS_ERR(new_ns)) {
struct mount *mnt = real_mount(m);
mnt->mnt_ns = new_ns;
- __mnt_make_longterm(mnt);
new_ns->root = mnt;
list_add(&new_ns->list, &mnt->mnt_list);
} else {
@@ -2615,7 +2574,7 @@
* it is a longterm mount, don't release mnt until
* we unmount before file sys is unregistered
*/
- mnt_make_longterm(mnt);
+ real_mount(mnt)->mnt_ns = MNT_NS_INTERNAL;
}
return mnt;
}
@@ -2625,7 +2584,9 @@
{
/* release long term mount so mount point can be released */
if (!IS_ERR_OR_NULL(mnt)) {
- mnt_make_shortterm(mnt);
+ br_write_lock(&vfsmount_lock);
+ real_mount(mnt)->mnt_ns = NULL;
+ br_write_unlock(&vfsmount_lock);
mntput(mnt);
}
}