4 files changed, 42 insertions, 60 deletions

diff --git a/fs/kernfs/dir.c b/fs/kernfs/dir.c
index 7f8afc1d08f1..1c9130a33048 100644
--- a/fs/kernfs/dir.c
+++ b/fs/kernfs/dir.c
@@ -127,7 +127,6 @@ static void kernfs_unlink_sibling(struct kernfs_node *kn)
                 kn->parent->dir.subdirs--;
 
         rb_erase(&kn->rb, &kn->parent->dir.children);
-        RB_CLEAR_NODE(&kn->rb);
 }
 
 /**
@@ -178,16 +177,18 @@ void kernfs_put_active(struct kernfs_node *kn)
 }
 
 /**
- * kernfs_drain - drain kernfs_node
- * @kn: kernfs_node to drain
+ *      kernfs_deactivate - deactivate kernfs_node
+ *      @kn: kernfs_node to deactivate
  *
- * Drain existing usages.
+ *      Deny new active references and drain existing ones.
  */
-static void kernfs_drain(struct kernfs_node *kn)
+static void kernfs_deactivate(struct kernfs_node *kn)
 {
         struct kernfs_root *root = kernfs_root(kn);
 
-        WARN_ON_ONCE(atomic_read(&kn->active) >= 0);
+        BUG_ON(!(kn->flags & KERNFS_REMOVED));
+
+        atomic_add(KN_DEACTIVATED_BIAS, &kn->active);
 
         if (kernfs_lockdep(kn)) {
                 rwsem_acquire(&kn->dep_map, 0, 0, _RET_IP_);
@@ -232,15 +233,13 @@ void kernfs_put(struct kernfs_node *kn)
                 return;
         root = kernfs_root(kn);
  repeat:
-        /*
-         * Moving/renaming is always done while holding reference.
+        /* Moving/renaming is always done while holding reference.
          * kn->parent won't change beneath us.
          */
         parent = kn->parent;
 
-        WARN_ONCE(atomic_read(&kn->active) != KN_DEACTIVATED_BIAS,
-                  "kernfs_put: %s/%s: released with incorrect active_ref %d\n",
-                  parent ? parent->name : "", kn->name, atomic_read(&kn->active));
+        WARN(!(kn->flags & KERNFS_REMOVED), "kernfs: free using entry: %s/%s\n",
+             parent ? parent->name : "", kn->name);
 
         if (kernfs_type(kn) == KERNFS_LINK)
                 kernfs_put(kn->symlink.target_kn);
@@ -282,8 +281,8 @@ static int kernfs_dop_revalidate(struct dentry *dentry, unsigned int flags)
         kn = dentry->d_fsdata;
         mutex_lock(&kernfs_mutex);
 
-        /* Force fresh lookup if removed */
-        if (kn->parent && RB_EMPTY_NODE(&kn->rb))
+        /* The kernfs node has been deleted */
+        if (kn->flags & KERNFS_REMOVED)
                 goto out_bad;
 
         /* The kernfs node has been moved? */
@@ -351,12 +350,11 @@ struct kernfs_node *kernfs_new_node(struct kernfs_root *root, const char *name,
         kn->ino = ret;
 
         atomic_set(&kn->count, 1);
-        atomic_set(&kn->active, KN_DEACTIVATED_BIAS);
-        RB_CLEAR_NODE(&kn->rb);
+        atomic_set(&kn->active, 0);
 
         kn->name = name;
         kn->mode = mode;
-        kn->flags = flags;
+        kn->flags = flags | KERNFS_REMOVED;
 
         return kn;
 
@@ -415,8 +413,6 @@ int kernfs_add_one(struct kernfs_addrm_cxt *acxt, struct kernfs_node *kn,
         struct kernfs_iattrs *ps_iattr;
         int ret;
 
-        WARN_ON_ONCE(atomic_read(&parent->active) < 0);
-
         if (has_ns != (bool)kn->ns) {
                 WARN(1, KERN_WARNING "kernfs: ns %s in '%s' for '%s'\n",
                      has_ns ? "required" : "invalid", parent->name, kn->name);
@@ -426,6 +422,9 @@ int kernfs_add_one(struct kernfs_addrm_cxt *acxt, struct kernfs_node *kn,
         if (kernfs_type(parent) != KERNFS_DIR)
                 return -EINVAL;
 
+        if (parent->flags & KERNFS_REMOVED)
+                return -ENOENT;
+
         kn->hash = kernfs_name_hash(kn->name, kn->ns);
         kn->parent = parent;
         kernfs_get(parent);
@@ -442,7 +441,8 @@ int kernfs_add_one(struct kernfs_addrm_cxt *acxt, struct kernfs_node *kn,
         }
 
         /* Mark the entry added into directory tree */
-        atomic_sub(KN_DEACTIVATED_BIAS, &kn->active);
+        kn->flags &= ~KERNFS_REMOVED;
+
         return 0;
 }
 
@@ -470,7 +470,7 @@ static void kernfs_remove_one(struct kernfs_addrm_cxt *acxt,
          * Removal can be called multiple times on the same node.  Only the
          * first invocation is effective and puts the base ref.
          */
-        if (atomic_read(&kn->active) < 0)
+        if (kn->flags & KERNFS_REMOVED)
                 return;
 
         if (kn->parent) {
@@ -484,7 +484,7 @@ static void kernfs_remove_one(struct kernfs_addrm_cxt *acxt,
                 }
         }
 
-        atomic_add(KN_DEACTIVATED_BIAS, &kn->active);
+        kn->flags |= KERNFS_REMOVED;
         kn->u.removed_list = acxt->removed;
         acxt->removed = kn;
 }
@@ -512,7 +512,7 @@ void kernfs_addrm_finish(struct kernfs_addrm_cxt *acxt)
 
                 acxt->removed = kn->u.removed_list;
 
-                kernfs_drain(kn);
+                kernfs_deactivate(kn);
                 kernfs_unmap_bin_file(kn);
                 kernfs_put(kn);
         }
@@ -610,7 +610,7 @@ struct kernfs_root *kernfs_create_root(struct kernfs_dir_ops *kdops, void *priv)
                 return ERR_PTR(-ENOMEM);
         }
 
-        atomic_sub(KN_DEACTIVATED_BIAS, &kn->active);
+        kn->flags &= ~KERNFS_REMOVED;
         kn->priv = priv;
         kn->dir.root = root;
 
@@ -662,13 +662,9 @@ struct kernfs_node *kernfs_create_dir_ns(struct kernfs_node *parent,
         kn->priv = priv;
 
         /* link in */
-        rc = -ENOENT;
-        if (kernfs_get_active(parent)) {
-                kernfs_addrm_start(&acxt);
-                rc = kernfs_add_one(&acxt, kn, parent);
-                kernfs_addrm_finish(&acxt);
-                kernfs_put_active(parent);
-        }
+        kernfs_addrm_start(&acxt);
+        rc = kernfs_add_one(&acxt, kn, parent);
+        kernfs_addrm_finish(&acxt);
 
         if (!rc)
                 return kn;
@@ -903,29 +899,27 @@ int kernfs_rename_ns(struct kernfs_node *kn, struct kernfs_node *new_parent,
 {
         int error;
 
+        mutex_lock(&kernfs_mutex);
+
         error = -ENOENT;
-        if (!kernfs_get_active(new_parent))
+        if ((kn->flags | new_parent->flags) & KERNFS_REMOVED)
                 goto out;
-        if (!kernfs_get_active(kn))
-                goto out_put_new_parent;
-
-        mutex_lock(&kernfs_mutex);
 
         error = 0;
         if ((kn->parent == new_parent) && (kn->ns == new_ns) &&
             (strcmp(kn->name, new_name) == 0))
-                goto out_unlock;        /* nothing to rename */
+                goto out;       /* nothing to rename */
 
         error = -EEXIST;
         if (kernfs_find_ns(new_parent, new_name, new_ns))
-                goto out_unlock;
+                goto out;
 
         /* rename kernfs_node */
         if (strcmp(kn->name, new_name) != 0) {
                 error = -ENOMEM;
                 new_name = kstrdup(new_name, GFP_KERNEL);
                 if (!new_name)
-                        goto out_unlock;
+                        goto out;
 
                 if (kn->flags & KERNFS_STATIC_NAME)
                         kn->flags &= ~KERNFS_STATIC_NAME;
@@ -947,12 +941,8 @@ int kernfs_rename_ns(struct kernfs_node *kn, struct kernfs_node *new_parent,
         kernfs_link_sibling(kn);
 
         error = 0;
-out_unlock:
+ out:
         mutex_unlock(&kernfs_mutex);
-        kernfs_put_active(kn);
-out_put_new_parent:
-        kernfs_put_active(new_parent);
-out:
         return error;
 }
 
@@ -972,7 +962,8 @@ static struct kernfs_node *kernfs_dir_pos(const void *ns,
         struct kernfs_node *parent, loff_t hash, struct kernfs_node *pos)
 {
         if (pos) {
-                int valid = pos->parent == parent && hash == pos->hash;
+                int valid = !(pos->flags & KERNFS_REMOVED) &&
+                        pos->parent == parent && hash == pos->hash;
                 kernfs_put(pos);
                 if (!valid)
                         pos = NULL;
diff --git a/fs/kernfs/file.c b/fs/kernfs/file.c
index 231a171f48b6..bdd38854ef65 100644
--- a/fs/kernfs/file.c
+++ b/fs/kernfs/file.c
@@ -856,13 +856,9 @@ struct kernfs_node *__kernfs_create_file(struct kernfs_node *parent,
         if (ops->mmap)
                 kn->flags |= KERNFS_HAS_MMAP;
 
-        rc = -ENOENT;
-        if (kernfs_get_active(parent)) {
-                kernfs_addrm_start(&acxt);
-                rc = kernfs_add_one(&acxt, kn, parent);
-                kernfs_addrm_finish(&acxt);
-                kernfs_put_active(parent);
-        }
+        kernfs_addrm_start(&acxt);
+        rc = kernfs_add_one(&acxt, kn, parent);
+        kernfs_addrm_finish(&acxt);
 
         if (rc) {
                 kernfs_put(kn);
diff --git a/fs/kernfs/kernfs-internal.h b/fs/kernfs/kernfs-internal.h
index 57a93f4d645c..c6ba5bc37a98 100644
--- a/fs/kernfs/kernfs-internal.h
+++ b/fs/kernfs/kernfs-internal.h
@@ -26,8 +26,7 @@ struct kernfs_iattrs {
         struct simple_xattrs    xattrs;
 };
 
-/* +1 to avoid triggering overflow warning when negating it */
-#define KN_DEACTIVATED_BIAS             (INT_MIN + 1)
+#define KN_DEACTIVATED_BIAS             INT_MIN
 
 /* KERNFS_TYPE_MASK and types are defined in include/linux/kernfs.h */
 
diff --git a/fs/kernfs/symlink.c b/fs/kernfs/symlink.c
index b2c106ca3434..a03e26036ef9 100644
--- a/fs/kernfs/symlink.c
+++ b/fs/kernfs/symlink.c
@@ -40,13 +40,9 @@ struct kernfs_node *kernfs_create_link(struct kernfs_node *parent,
         kn->symlink.target_kn = target;
         kernfs_get(target);     /* ref owned by symlink */
 
-        error = -ENOENT;
-        if (kernfs_get_active(parent)) {
-                kernfs_addrm_start(&acxt);
-                error = kernfs_add_one(&acxt, kn, parent);
-                kernfs_addrm_finish(&acxt);
-                kernfs_put_active(parent);
-        }
+        kernfs_addrm_start(&acxt);
+        error = kernfs_add_one(&acxt, kn, parent);
+        kernfs_addrm_finish(&acxt);
 
         if (!error)
                 return kn;