Merge remote-tracking branch 'userns/for-next'

[karo-tx-linux.git] / fs / namespace.c

diff --git a/fs/namespace.c b/fs/namespace.c
index da5c494834306178dc9efd3b3826d1b7f0e0d17b..ca81c46ea649831ea3767ba114ba9a5c360df1a9 100644 (file)
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -39,7 +39,7 @@ static int mnt_group_start = 1;
 static struct list_head *mount_hashtable __read_mostly;
 static struct list_head *mountpoint_hashtable __read_mostly;
 static struct kmem_cache *mnt_cache __read_mostly;
-static struct rw_semaphore namespace_sem;
+static DECLARE_RWSEM(namespace_sem);
 
 /* /sys/fs */
 struct kobject *fs_kobj;
@@ -197,6 +197,7 @@ static struct mount *alloc_vfsmnt(const char *name)
                INIT_LIST_HEAD(&mnt->mnt_share);
                INIT_LIST_HEAD(&mnt->mnt_slave_list);
                INIT_LIST_HEAD(&mnt->mnt_slave);
+               INIT_LIST_HEAD(&mnt->mnt_mp_list);
 #ifdef CONFIG_FSNOTIFY
                INIT_HLIST_HEAD(&mnt->mnt_fsnotify_marks);
 #endif
@@ -636,6 +637,7 @@ static struct mountpoint *new_mountpoint(struct dentry *dentry)
        mp->m_dentry = dentry;
        mp->m_count = 1;
        list_add(&mp->m_hash, chain);
+       INIT_LIST_HEAD(&mp->m_list);
        return mp;
 }
 
@@ -643,6 +645,7 @@ static void put_mountpoint(struct mountpoint *mp)
 {
        if (!--mp->m_count) {
                struct dentry *dentry = mp->m_dentry;
+               BUG_ON(!list_empty(&mp->m_list));
                spin_lock(&dentry->d_lock);
                dentry->d_flags &= ~DCACHE_MOUNTED;
                spin_unlock(&dentry->d_lock);
@@ -689,6 +692,7 @@ static void detach_mnt(struct mount *mnt, struct path *old_path)
        mnt->mnt_mountpoint = mnt->mnt.mnt_root;
        list_del_init(&mnt->mnt_child);
        list_del_init(&mnt->mnt_hash);
+       list_del_init(&mnt->mnt_mp_list);
        put_mountpoint(mnt->mnt_mp);
        mnt->mnt_mp = NULL;
 }
@@ -705,6 +709,7 @@ void mnt_set_mountpoint(struct mount *mnt,
        child_mnt->mnt_mountpoint = dget(mp->m_dentry);
        child_mnt->mnt_parent = mnt;
        child_mnt->mnt_mp = mp;
+       list_add_tail(&child_mnt->mnt_mp_list, &mp->m_list);
 }
 
 /*
@@ -1191,6 +1196,7 @@ void umount_tree(struct mount *mnt, int propagate)
                list_del_init(&p->mnt_child);
                if (mnt_has_parent(p)) {
                        p->mnt_parent->mnt_ghosts++;
+                       list_del_init(&p->mnt_mp_list);
                        put_mountpoint(p->mnt_mp);
                        p->mnt_mp = NULL;
                }
@@ -1289,6 +1295,30 @@ static int do_umount(struct mount *mnt, int flags)
        return retval;
 }
 
+void detach_mounts(struct dentry *dentry)
+{
+       struct mountpoint *mp;
+       struct mount *mnt;
+
+       namespace_lock();
+       if (!d_mountpoint(dentry))
+               goto out_unlock;
+
+       mp = new_mountpoint(dentry);
+       if (IS_ERR(mp))
+               goto out_unlock;
+
+       br_write_lock(&vfsmount_lock);
+       while (!list_empty(&mp->m_list)) {
+               mnt = list_first_entry(&mp->m_list, struct mount, mnt_mp_list);
+               umount_tree(mnt, 1);
+       }
+       br_write_unlock(&vfsmount_lock);
+       put_mountpoint(mp);
+out_unlock:
+       namespace_unlock();
+}
+
 /* 
  * Is the caller allowed to modify his namespace?
  */
@@ -1849,14 +1879,10 @@ static int do_remount(struct path *path, int flags, int mnt_flags,
                br_write_lock(&vfsmount_lock);
                mnt_flags |= mnt->mnt.mnt_flags & MNT_PROPAGATION_MASK;
                mnt->mnt.mnt_flags = mnt_flags;
-               br_write_unlock(&vfsmount_lock);
-       }
-       up_write(&sb->s_umount);
-       if (!err) {
-               br_write_lock(&vfsmount_lock);
                touch_mnt_namespace(mnt->mnt_ns);
                br_write_unlock(&vfsmount_lock);
        }
+       up_write(&sb->s_umount);
        return err;
 }
 
@@ -2444,9 +2470,7 @@ static struct mnt_namespace *dup_mnt_ns(struct mnt_namespace *mnt_ns,
                return ERR_CAST(new);
        }
        new_ns->root = new;
-       br_write_lock(&vfsmount_lock);
        list_add_tail(&new_ns->list, &new->mnt_list);
-       br_write_unlock(&vfsmount_lock);
 
        /*
         * Second pass: switch the tsk->fs->* elements and mark new vfsmounts
@@ -2767,8 +2791,6 @@ void __init mnt_init(void)
        unsigned u;
        int err;
 
-       init_rwsem(&namespace_sem);
-
        mnt_cache = kmem_cache_create("mnt_cache", sizeof(struct mount),
                        0, SLAB_HWCACHE_ALIGN | SLAB_PANIC, NULL);
 
@@ -2802,11 +2824,7 @@ void put_mnt_ns(struct mnt_namespace *ns)
 {
        if (!atomic_dec_and_test(&ns->count))
                return;
-       namespace_lock();
-       br_write_lock(&vfsmount_lock);
-       umount_tree(ns->root, 0);
-       br_write_unlock(&vfsmount_lock);
-       namespace_unlock();
+       drop_collected_mounts(&ns->root->mnt);
        free_mnt_ns(ns);
 }
 
@@ -2875,7 +2893,7 @@ bool fs_fully_visible(struct file_system_type *type)
        if (unlikely(!ns))
                return false;
 
-       namespace_lock();
+       down_read(&namespace_sem);
        list_for_each_entry(mnt, &ns->list, mnt_list) {
                struct mount *child;
                if (mnt->mnt.mnt_sb->s_type != type)
@@ -2896,7 +2914,7 @@ bool fs_fully_visible(struct file_system_type *type)
        next:   ;
        }
 found:
-       namespace_unlock();
+       up_read(&namespace_sem);
        return visible;
 }