Revert "UBUNTU: SAUCE: Import aufs driver"

[mirror_ubuntu-zesty-kernel.git] / fs / namespace.c

diff --git a/fs/namespace.c b/fs/namespace.c
index b5b1259e064f8d9661110ba1f1f73d1a0ff19d51..0730c16f6c673243608d20bd93d148cd55a921ca 100644 (file)
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -742,26 +742,50 @@ static struct mountpoint *lookup_mountpoint(struct dentry *dentry)
        return NULL;
 }
 
-static struct mountpoint *new_mountpoint(struct dentry *dentry)
+static struct mountpoint *get_mountpoint(struct dentry *dentry)
 {
-       struct hlist_head *chain = mp_hash(dentry);
-       struct mountpoint *mp;
+       struct mountpoint *mp, *new = NULL;
        int ret;
 
-       mp = kmalloc(sizeof(struct mountpoint), GFP_KERNEL);
-       if (!mp)
+       if (d_mountpoint(dentry)) {
+mountpoint:
+               read_seqlock_excl(&mount_lock);
+               mp = lookup_mountpoint(dentry);
+               read_sequnlock_excl(&mount_lock);
+               if (mp)
+                       goto done;
+       }
+
+       if (!new)
+               new = kmalloc(sizeof(struct mountpoint), GFP_KERNEL);
+       if (!new)
                return ERR_PTR(-ENOMEM);
 
+
+       /* Exactly one processes may set d_mounted */
        ret = d_set_mounted(dentry);
-       if (ret) {
-               kfree(mp);
-               return ERR_PTR(ret);
-       }
 
-       mp->m_dentry = dentry;
-       mp->m_count = 1;
-       hlist_add_head(&mp->m_hash, chain);
-       INIT_HLIST_HEAD(&mp->m_list);
+       /* Someone else set d_mounted? */
+       if (ret == -EBUSY)
+               goto mountpoint;
+
+       /* The dentry is not available as a mountpoint? */
+       mp = ERR_PTR(ret);
+       if (ret)
+               goto done;
+
+       /* Add the new mountpoint to the hash table */
+       read_seqlock_excl(&mount_lock);
+       new->m_dentry = dentry;
+       new->m_count = 1;
+       hlist_add_head(&new->m_hash, mp_hash(dentry));
+       INIT_HLIST_HEAD(&new->m_list);
+       read_sequnlock_excl(&mount_lock);
+
+       mp = new;
+       new = NULL;
+done:
+       kfree(new);
        return mp;
 }
 
@@ -1548,7 +1572,7 @@ static int do_umount(struct mount *mnt, int flags)
                 * Special case for "unmounting" root ...
                 * we just try to remount it readonly.
                 */
-               if (!capable(CAP_SYS_ADMIN))
+               if (!ns_capable(sb->s_user_ns, CAP_SYS_ADMIN))
                        return -EPERM;
                down_write(&sb->s_umount);
                if (!(sb->s_flags & MS_RDONLY))
@@ -1595,11 +1619,11 @@ void __detach_mounts(struct dentry *dentry)
        struct mount *mnt;
 
        namespace_lock();
+       lock_mount_hash();
        mp = lookup_mountpoint(dentry);
        if (IS_ERR_OR_NULL(mp))
                goto out_unlock;
 
-       lock_mount_hash();
        event++;
        while (!hlist_empty(&mp->m_list)) {
                mnt = hlist_entry(mp->m_list.first, struct mount, mnt_mp_list);
@@ -1609,9 +1633,9 @@ void __detach_mounts(struct dentry *dentry)
                }
                else umount_tree(mnt, UMOUNT_CONNECTED);
        }
-       unlock_mount_hash();
        put_mountpoint(mp);
 out_unlock:
+       unlock_mount_hash();
        namespace_unlock();
 }
 
@@ -2038,9 +2062,7 @@ retry:
        namespace_lock();
        mnt = lookup_mnt(path);
        if (likely(!mnt)) {
-               struct mountpoint *mp = lookup_mountpoint(dentry);
-               if (!mp)
-                       mp = new_mountpoint(dentry);
+               struct mountpoint *mp = get_mountpoint(dentry);
                if (IS_ERR(mp)) {
                        namespace_unlock();
                        inode_unlock(dentry->d_inode);
@@ -2059,7 +2081,11 @@ retry:
 static void unlock_mount(struct mountpoint *where)
 {
        struct dentry *dentry = where->m_dentry;
+
+       read_seqlock_excl(&mount_lock);
        put_mountpoint(where);
+       read_sequnlock_excl(&mount_lock);
+
        namespace_unlock();
        inode_unlock(dentry->d_inode);
 }
@@ -2276,7 +2302,7 @@ static int do_remount(struct path *path, int flags, int mnt_flags,
        down_write(&sb->s_umount);
        if (flags & MS_BIND)
                err = change_mount_flags(path->mnt, flags);
-       else if (!capable(CAP_SYS_ADMIN))
+       else if (!ns_capable(sb->s_user_ns, CAP_SYS_ADMIN))
                err = -EPERM;
        else
                err = do_remount_sb(sb, flags, data, 0);
@@ -3135,9 +3161,9 @@ SYSCALL_DEFINE2(pivot_root, const char __user *, new_root,
        touch_mnt_namespace(current->nsproxy->mnt_ns);
        /* A moved mount should not expire automatically */
        list_del_init(&new_mnt->mnt_expire);
+       put_mountpoint(root_mp);
        unlock_mount_hash();
        chroot_fs_refs(&root, &new);
-       put_mountpoint(root_mp);
        error = 0;
 out4:
        unlock_mount(old_mp);