diff --git a/fs/dcache.c b/fs/dcache.c
index 2c289487a40730c5120589bae7837e8893c34ab5..a94b9fdf20516352968a8b61257afd66c93b0d14 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -2558,7 +2558,7 @@ global_root:
if (!slash)
error = prepend(buffer, buflen, "/", 1);
if (!error)
- error = is_mounted(vfsmnt) ? 1 : 2;
+ error = real_mount(vfsmnt)->mnt_ns ? 1 : 2;
goto out;
}
diff --git a/fs/fs_struct.c b/fs/fs_struct.c
index 5df4775fea03638f14d1408cfe16408e8a0ed6d7..e159e682ad4c68b16b82ef7eeafa889c05877580 100644
--- a/fs/fs_struct.c
+++ b/fs/fs_struct.c
@@ -6,6 +6,18 @@
#include <linux/fs_struct.h>
#include "internal.h"
+static inline void path_get_longterm(struct path *path)
+{
+ path_get(path);
+ mnt_make_longterm(path->mnt);
+}
+
+static inline void path_put_longterm(struct path *path)
+{
+ mnt_make_shortterm(path->mnt);
+ path_put(path);
+}
+
/*
* Replace the fs->{rootmnt,root} with {mnt,dentry}. Put the old values.
* It can block.
@@ -14,7 +26,7 @@ void set_fs_root(struct fs_struct *fs, struct path *path)
{
struct path old_root;
- path_get(path);
+ path_get_longterm(path);
spin_lock(&fs->lock);
write_seqcount_begin(&fs->seq);
old_root = fs->root;
@@ -22,7 +34,7 @@ void set_fs_root(struct fs_struct *fs, struct path *path)
write_seqcount_end(&fs->seq);
spin_unlock(&fs->lock);
if (old_root.dentry)
- path_put(&old_root);
+ path_put_longterm(&old_root);
}
/*
@@ -33,7 +45,7 @@ void set_fs_pwd(struct fs_struct *fs, struct path *path)
{
struct path old_pwd;
- path_get(path);
+ path_get_longterm(path);
spin_lock(&fs->lock);
write_seqcount_begin(&fs->seq);
old_pwd = fs->pwd;
@@ -42,7 +54,7 @@ void set_fs_pwd(struct fs_struct *fs, struct path *path)
spin_unlock(&fs->lock);
if (old_pwd.dentry)
- path_put(&old_pwd);
+ path_put_longterm(&old_pwd);
}
static inline int replace_path(struct path *p, const struct path *old, const struct path *new)
@@ -72,7 +84,7 @@ void chroot_fs_refs(struct path *old_root, struct path *new_root)
write_seqcount_end(&fs->seq);
while (hits--) {
count++;
- path_get(new_root);
+ path_get_longterm(new_root);
}
spin_unlock(&fs->lock);
}
@@ -80,13 +92,13 @@ void chroot_fs_refs(struct path *old_root, struct path *new_root)
} while_each_thread(g, p);
read_unlock(&tasklist_lock);
while (count--)
- path_put(old_root);
+ path_put_longterm(old_root);
}
void free_fs_struct(struct fs_struct *fs)
{
- path_put(&fs->root);
- path_put(&fs->pwd);
+ path_put_longterm(&fs->root);
+ path_put_longterm(&fs->pwd);
kmem_cache_free(fs_cachep, fs);
}
@@ -120,9 +132,9 @@ struct fs_struct *copy_fs_struct(struct fs_struct *old)
spin_lock(&old->lock);
fs->root = old->root;
- path_get(&fs->root);
+ path_get_longterm(&fs->root);
fs->pwd = old->pwd;
- path_get(&fs->pwd);
+ path_get_longterm(&fs->pwd);
spin_unlock(&old->lock);
}
return fs;
diff --git a/fs/internal.h b/fs/internal.h
index faf568012d99664977d9c1a20f0bb89bf4a4cd53..9962c59ba280b1c75d78adc55b8491733075a5e0 100644
--- a/fs/internal.h
+++ b/fs/internal.h
@@ -50,6 +50,8 @@ extern int copy_mount_string(const void __user *, char **);
extern struct vfsmount *lookup_mnt(struct path *);
extern int finish_automount(struct vfsmount *, struct path *);
+extern void mnt_make_longterm(struct vfsmount *);
+extern void mnt_make_shortterm(struct vfsmount *);
extern int sb_prepare_remount_readonly(struct super_block *);
extern void __init mnt_init(void);
diff --git a/fs/mount.h b/fs/mount.h
index 05a2a1185efcf2e560012c33042ceb8c406dc119..4ef36d93e5a241822e10c21f93dc72d7137d32ec 100644
--- a/fs/mount.h
+++ b/fs/mount.h
@@ -22,6 +22,7 @@ struct mount {
struct vfsmount mnt;
#ifdef CONFIG_SMP
struct mnt_pcp __percpu *mnt_pcp;
+ atomic_t mnt_longterm; /* how many of the refs are longterm */
#else
int mnt_count;
int mnt_writers;
@@ -48,8 +49,6 @@ struct mount {
int mnt_ghosts;
};
-#define MNT_NS_INTERNAL ERR_PTR(-EINVAL) /* distinct from any mnt_namespace */
-
static inline struct mount *real_mount(struct vfsmount *mnt)
{
return container_of(mnt, struct mount, mnt);
@@ -60,12 +59,6 @@ static inline int mnt_has_parent(struct mount *mnt)
return mnt != mnt->mnt_parent;
}
-static inline int is_mounted(struct vfsmount *mnt)
-{
- /* neither detached nor internal? */
- return !IS_ERR_OR_NULL(real_mount(mnt));
-}
-
extern struct mount *__lookup_mnt(struct vfsmount *, struct dentry *, int);
static inline void get_mnt_ns(struct mnt_namespace *ns)
diff --git a/fs/namespace.c b/fs/namespace.c
index 324194eabeff38b5f5594764eb4ccaa9efe2e7c2..4e465397e45609f6cca3532d2cc15f434b8841c5 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -621,6 +621,21 @@ static void attach_mnt(struct mount *mnt, struct path *path)
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
*/
@@ -634,8 +649,10 @@ static void commit_tree(struct mount *mnt)
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);
@@ -787,8 +804,7 @@ static void mntput_no_expire(struct mount *mnt)
put_again:
#ifdef CONFIG_SMP
br_read_lock(vfsmount_lock);
- if (likely(mnt->mnt_ns)) {
- /* shouldn't be the last one */
+ if (likely(atomic_read(&mnt->mnt_longterm))) {
mnt_add_count(mnt, -1);
br_read_unlock(vfsmount_lock);
return;
@@ -1057,6 +1073,8 @@ void umount_tree(struct mount *mnt, int propagate, struct list_head *kill)
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)) {
@@ -2190,6 +2208,23 @@ static struct mnt_namespace *alloc_mnt_ns(void)
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.
@@ -2229,13 +2264,18 @@ static struct mnt_namespace *dup_mnt_ns(struct mnt_namespace *mnt_ns,
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;
}
}
@@ -2279,6 +2319,7 @@ static struct mnt_namespace *create_mnt_ns(struct vfsmount *m)
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 {
@@ -2573,7 +2614,7 @@ struct vfsmount *kern_mount_data(struct file_system_type *type, void *data)
* it is a longterm mount, don't release mnt until
* we unmount before file sys is unregistered
*/
- real_mount(mnt)->mnt_ns = MNT_NS_INTERNAL;
+ mnt_make_longterm(mnt);
}
return mnt;
}
@@ -2583,9 +2624,7 @@ void kern_unmount(struct vfsmount *mnt)
{
/* release long term mount so mount point can be released */
if (!IS_ERR_OR_NULL(mnt)) {
- br_write_lock(vfsmount_lock);
- real_mount(mnt)->mnt_ns = NULL;
- br_write_unlock(vfsmount_lock);
+ mnt_make_shortterm(mnt);
mntput(mnt);
}
}