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>

1 files changed, 8 insertions, 1 deletions

diff --git a/fs/mount.h b/fs/mount.h
index 4ef36d93e5a2..05a2a1185efc 100644
--- a/fs/mount.h
+++ b/fs/mount.h
@@ -22,7 +22,6 @@ 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;
@@ -49,6 +48,8 @@ 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);
@@ -59,6 +60,12 @@ 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)