diff --git a/fs/kernfs/dir.c b/fs/kernfs/dir.c
index 2193d30156efeaf1bf07a772e9fee731f3d6f40d..3ac93737174af67f3b7888d478c973c60aec1efd 100644
--- a/fs/kernfs/dir.c
+++ b/fs/kernfs/dir.c
@@ -106,18 +106,24 @@ static int kernfs_link_sibling(struct kernfs_node *kn)
* kernfs_unlink_sibling - unlink kernfs_node from sibling rbtree
* @kn: kernfs_node of interest
*
- * Unlink @kn from its sibling rbtree which starts from
- * kn->parent->dir.children.
+ * Try to unlink @kn from its sibling rbtree which starts from
+ * kn->parent->dir.children. Returns %true if @kn was actually
+ * removed, %false if @kn wasn't on the rbtree.
*
* Locking:
* mutex_lock(kernfs_mutex)
*/
-static void kernfs_unlink_sibling(struct kernfs_node *kn)
+static bool kernfs_unlink_sibling(struct kernfs_node *kn)
{
+ if (RB_EMPTY_NODE(&kn->rb))
+ return false;
+
if (kernfs_type(kn) == KERNFS_DIR)
kn->parent->dir.subdirs--;
rb_erase(&kn->rb, &kn->parent->dir.children);
+ RB_CLEAR_NODE(&kn->rb);
+ return true;
}
/**
@@ -171,26 +177,34 @@ void kernfs_put_active(struct kernfs_node *kn)
* kernfs_deactivate - deactivate kernfs_node
* @kn: kernfs_node to deactivate
*
- * Deny new active references and drain existing ones.
+ * Deny new active references and drain existing ones. Mutiple
+ * removers may invoke this function concurrently on @kn and all will
+ * return after deactivation and draining are complete.
*/
static void kernfs_deactivate(struct kernfs_node *kn)
+ __releases(&kernfs_mutex) __acquires(&kernfs_mutex)
{
struct kernfs_root *root = kernfs_root(kn);
+ lockdep_assert_held(&kernfs_mutex);
BUG_ON(!(kn->flags & KERNFS_REMOVED));
if (!(kernfs_type(kn) & KERNFS_ACTIVE_REF))
return;
- if (kn->flags & KERNFS_LOCKDEP)
- rwsem_acquire(&kn->dep_map, 0, 0, _RET_IP_);
+ /* only the first invocation on @kn should deactivate it */
+ if (atomic_read(&kn->active) >= 0)
+ atomic_add(KN_DEACTIVATED_BIAS, &kn->active);
- atomic_add(KN_DEACTIVATED_BIAS, &kn->active);
+ mutex_unlock(&kernfs_mutex);
- if ((kn->flags & KERNFS_LOCKDEP) &&
- atomic_read(&kn->active) != KN_DEACTIVATED_BIAS)
- lock_contended(&kn->dep_map, _RET_IP_);
+ if (kn->flags & KERNFS_LOCKDEP) {
+ rwsem_acquire(&kn->dep_map, 0, 0, _RET_IP_);
+ if (atomic_read(&kn->active) != KN_DEACTIVATED_BIAS)
+ lock_contended(&kn->dep_map, _RET_IP_);
+ }
+ /* but everyone should wait for draining */
wait_event(root->deactivate_waitq,
atomic_read(&kn->active) == KN_DEACTIVATED_BIAS);
@@ -198,6 +212,8 @@ static void kernfs_deactivate(struct kernfs_node *kn)
lock_acquired(&kn->dep_map, _RET_IP_);
rwsem_release(&kn->dep_map, 1, _RET_IP_);
}
+
+ mutex_lock(&kernfs_mutex);
}
/**
@@ -347,6 +363,7 @@ static struct kernfs_node *__kernfs_new_node(struct kernfs_root *root,
atomic_set(&kn->count, 1);
atomic_set(&kn->active, 0);
+ RB_CLEAR_NODE(&kn->rb);
kn->name = name;
kn->mode = mode;
@@ -453,49 +470,6 @@ int kernfs_add_one(struct kernfs_addrm_cxt *acxt, struct kernfs_node *kn)
return 0;
}
-/**
- * kernfs_remove_one - remove kernfs_node from parent
- * @acxt: addrm context to use
- * @kn: kernfs_node to be removed
- *
- * Mark @kn removed and drop nlink of parent inode if @kn is a
- * directory. @kn is unlinked from the children list.
- *
- * This function should be called between calls to
- * kernfs_addrm_start() and kernfs_addrm_finish() and should be
- * passed the same @acxt as passed to kernfs_addrm_start().
- *
- * LOCKING:
- * Determined by kernfs_addrm_start().
- */
-static void kernfs_remove_one(struct kernfs_addrm_cxt *acxt,
- struct kernfs_node *kn)
-{
- struct kernfs_iattrs *ps_iattr;
-
- /*
- * Removal can be called multiple times on the same node. Only the
- * first invocation is effective and puts the base ref.
- */
- if (kn->flags & KERNFS_REMOVED)
- return;
-
- if (kn->parent) {
- kernfs_unlink_sibling(kn);
-
- /* Update timestamps on the parent */
- ps_iattr = kn->parent->iattr;
- if (ps_iattr) {
- ps_iattr->ia_iattr.ia_ctime = CURRENT_TIME;
- ps_iattr->ia_iattr.ia_mtime = CURRENT_TIME;
- }
- }
-
- kn->flags |= KERNFS_REMOVED;
- kn->u.removed_list = acxt->removed;
- acxt->removed = kn;
-}
-
/**
* kernfs_addrm_finish - finish up kernfs_node add/remove
* @acxt: addrm context to finish up
@@ -519,7 +493,6 @@ void kernfs_addrm_finish(struct kernfs_addrm_cxt *acxt)
acxt->removed = kn->u.removed_list;
- kernfs_deactivate(kn);
kernfs_unmap_bin_file(kn);
kernfs_put(kn);
}
@@ -828,20 +801,54 @@ static struct kernfs_node *kernfs_next_descendant_post(struct kernfs_node *pos,
static void __kernfs_remove(struct kernfs_addrm_cxt *acxt,
struct kernfs_node *kn)
{
- struct kernfs_node *pos, *next;
+ struct kernfs_node *pos;
+
+ lockdep_assert_held(&kernfs_mutex);
if (!kn)
return;
pr_debug("kernfs %s: removing\n", kn->name);
- next = NULL;
+ /* disable lookup and node creation under @kn */
+ pos = NULL;
+ while ((pos = kernfs_next_descendant_post(pos, kn)))
+ pos->flags |= KERNFS_REMOVED;
+
+ /* deactivate and unlink the subtree node-by-node */
do {
- pos = next;
- next = kernfs_next_descendant_post(pos, kn);
- if (pos)
- kernfs_remove_one(acxt, pos);
- } while (next);
+ pos = kernfs_leftmost_descendant(kn);
+
+ /*
+ * kernfs_deactivate() drops kernfs_mutex temporarily and
+ * @pos's base ref could have been put by someone else by
+ * the time the function returns. Make sure it doesn't go
+ * away underneath us.
+ */
+ kernfs_get(pos);
+
+ kernfs_deactivate(pos);
+
+ /*
+ * kernfs_unlink_sibling() succeeds once per node. Use it
+ * to decide who's responsible for cleanups.
+ */
+ if (!pos->parent || kernfs_unlink_sibling(pos)) {
+ struct kernfs_iattrs *ps_iattr =
+ pos->parent ? pos->parent->iattr : NULL;
+
+ /* update timestamps on the parent */
+ if (ps_iattr) {
+ ps_iattr->ia_iattr.ia_ctime = CURRENT_TIME;
+ ps_iattr->ia_iattr.ia_mtime = CURRENT_TIME;
+ }
+
+ pos->u.removed_list = acxt->removed;
+ acxt->removed = pos;
+ }
+
+ kernfs_put(pos);
+ } while (pos != kn);
}
/**