Merge tag 'watchdog-for-linus-v4.10' of git://git.kernel.org/pub/scm/linux/kernel...

[linux-2.6-block.git] / fs / namespace.c

diff --git a/fs/namespace.c b/fs/namespace.c
index e6c234b1a6456c1364bcc06b029f3cc4a155d5bd..b5b1259e064f8d9661110ba1f1f73d1a0ff19d51 100644 (file)
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -96,10 +96,6 @@ static inline struct hlist_head *mp_hash(struct dentry *dentry)
        return &mountpoint_hashtable[tmp & mp_hash_mask];
 }
 
-/*
- * allocation is serialized by namespace_sem, but we need the spinlock to
- * serialize with freeing.
- */
 static int mnt_alloc_id(struct mount *mnt)
 {
        int res;
@@ -678,7 +674,7 @@ out:
  *
  * lookup_mnt takes a reference to the found vfsmount.
  */
-struct vfsmount *lookup_mnt(struct path *path)
+struct vfsmount *lookup_mnt(const struct path *path)
 {
        struct mount *child_mnt;
        struct vfsmount *m;
@@ -1034,6 +1030,8 @@ static struct mount *clone_mnt(struct mount *old, struct dentry *root,
                if (IS_MNT_SLAVE(old))
                        list_add(&mnt->mnt_slave, &old->mnt_slave);
                mnt->mnt_master = old->mnt_master;
+       } else {
+               CLEAR_MNT_SHARED(mnt);
        }
        if (flag & CL_MAKE_SHARED)
                set_mnt_shared(mnt);
@@ -1159,7 +1157,36 @@ struct vfsmount *mntget(struct vfsmount *mnt)
 }
 EXPORT_SYMBOL(mntget);
 
-struct vfsmount *mnt_clone_internal(struct path *path)
+/* path_is_mountpoint() - Check if path is a mount in the current
+ *                          namespace.
+ *
+ *  d_mountpoint() can only be used reliably to establish if a dentry is
+ *  not mounted in any namespace and that common case is handled inline.
+ *  d_mountpoint() isn't aware of the possibility there may be multiple
+ *  mounts using a given dentry in a different namespace. This function
+ *  checks if the passed in path is a mountpoint rather than the dentry
+ *  alone.
+ */
+bool path_is_mountpoint(const struct path *path)
+{
+       unsigned seq;
+       bool res;
+
+       if (!d_mountpoint(path->dentry))
+               return false;
+
+       rcu_read_lock();
+       do {
+               seq = read_seqbegin(&mount_lock);
+               res = __path_is_mountpoint(path);
+       } while (read_seqretry(&mount_lock, seq));
+       rcu_read_unlock();
+
+       return res;
+}
+EXPORT_SYMBOL(path_is_mountpoint);
+
+struct vfsmount *mnt_clone_internal(const struct path *path)
 {
        struct mount *p;
        p = clone_mnt(real_mount(path->mnt), path->dentry, CL_PRIVATE);
@@ -1758,7 +1785,7 @@ out:
 
 /* Caller should check returned pointer for errors */
 
-struct vfsmount *collect_mounts(struct path *path)
+struct vfsmount *collect_mounts(const struct path *path)
 {
        struct mount *tree;
        namespace_lock();
@@ -1791,7 +1818,7 @@ void drop_collected_mounts(struct vfsmount *mnt)
  *
  * Release with mntput().
  */
-struct vfsmount *clone_private_mount(struct path *path)
+struct vfsmount *clone_private_mount(const struct path *path)
 {
        struct mount *old_mnt = real_mount(path->mnt);
        struct mount *new_mnt;
@@ -1799,9 +1826,7 @@ struct vfsmount *clone_private_mount(struct path *path)
        if (IS_MNT_UNBINDABLE(old_mnt))
                return ERR_PTR(-EINVAL);
 
-       down_read(&namespace_sem);
        new_mnt = clone_mnt(old_mnt, path->dentry, CL_PRIVATE);
-       up_read(&namespace_sem);
        if (IS_ERR(new_mnt))
                return ERR_CAST(new_mnt);
 
@@ -2997,7 +3022,7 @@ bool is_path_reachable(struct mount *mnt, struct dentry *dentry,
        return &mnt->mnt == root->mnt && is_subdir(dentry, root->dentry);
 }
 
-bool path_is_under(struct path *path1, struct path *path2)
+bool path_is_under(const struct path *path1, const struct path *path2)
 {
        bool res;
        read_seqlock_excl(&mount_lock);