diff --git a/fs/mount.h b/fs/mount.h index e9f48e563c0f..ffb613cdfeee 100644 --- a/fs/mount.h +++ b/fs/mount.h @@ -8,7 +8,11 @@ struct mnt_namespace { struct ns_common ns; struct mount * root; - struct rb_root mounts; /* Protected by namespace_sem */ + struct { + struct rb_root mounts; /* Protected by namespace_sem */ + struct rb_node *mnt_last_node; /* last (rightmost) mount in the rbtree */ + struct rb_node *mnt_first_node; /* first (leftmost) mount in the rbtree */ + }; struct user_namespace *user_ns; struct ucounts *ucounts; u64 seq; /* Sequence number to prevent loops */ @@ -154,8 +158,13 @@ static inline bool mnt_ns_attached(const struct mount *mnt) static inline void move_from_ns(struct mount *mnt, struct list_head *dt_list) { + struct mnt_namespace *ns = mnt->mnt_ns; WARN_ON(!mnt_ns_attached(mnt)); - rb_erase(&mnt->mnt_node, &mnt->mnt_ns->mounts); + if (ns->mnt_last_node == &mnt->mnt_node) + ns->mnt_last_node = rb_prev(&mnt->mnt_node); + if (ns->mnt_first_node == &mnt->mnt_node) + ns->mnt_first_node = rb_next(&mnt->mnt_node); + rb_erase(&mnt->mnt_node, &ns->mounts); RB_CLEAR_NODE(&mnt->mnt_node); list_add_tail(&mnt->mnt_list, dt_list); } diff --git a/fs/namespace.c b/fs/namespace.c index e37927b76814..4dd3137b37e2 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -1155,16 +1155,25 @@ static void mnt_add_to_ns(struct mnt_namespace *ns, struct mount *mnt) { struct rb_node **link = &ns->mounts.rb_node; struct rb_node *parent = NULL; + bool mnt_first_node = true, mnt_last_node = true; WARN_ON(mnt_ns_attached(mnt)); mnt->mnt_ns = ns; while (*link) { parent = *link; - if (mnt->mnt_id_unique < node_to_mount(parent)->mnt_id_unique) + if (mnt->mnt_id_unique < node_to_mount(parent)->mnt_id_unique) { link = &parent->rb_left; - else + mnt_last_node = false; + } else { link = &parent->rb_right; + mnt_first_node = false; + } } + + if (mnt_last_node) + ns->mnt_last_node = &mnt->mnt_node; + if (mnt_first_node) + ns->mnt_first_node = &mnt->mnt_node; rb_link_node(&mnt->mnt_node, parent, link); rb_insert_color(&mnt->mnt_node, &ns->mounts); } @@ -5559,9 +5568,9 @@ static ssize_t do_listmount(struct mnt_namespace *ns, u64 mnt_parent_id, if (!last_mnt_id) { if (reverse) - first = node_to_mount(rb_last(&ns->mounts)); + first = node_to_mount(ns->mnt_last_node); else - first = node_to_mount(rb_first(&ns->mounts)); + first = node_to_mount(ns->mnt_first_node); } else { if (reverse) first = mnt_find_id_at_reverse(ns, last_mnt_id - 1);