Revert "kernfs: invoke kernfs_unmap_bin_file() directly from __kernfs_remove()"

This reverts commit f601f9a2bf7dc1f7ee18feece4c4e2fc6845d6c4.

Tejun writes:
        I'm sorry but can you please revert the whole series?
        get_active() waiting while a node is deactivated has potential
        to lead to deadlock and that deactivate/reactivate interface is
        something fundamentally flawed and that cgroup will have to work
        with the remove_self() like everybody else.  IOW, I think the
        first posting was correct.

Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

3 files changed, 14 insertions, 35 deletions

diff --git a/fs/kernfs/dir.c b/fs/kernfs/dir.c
index f878e4f2efe7..e565ec096ae9 100644
--- a/fs/kernfs/dir.c
+++ b/fs/kernfs/dir.c
@@ -121,17 +121,13 @@ static int kernfs_link_sibling(struct kernfs_node *kn)
  *      Locking:
  *      mutex_lock(kernfs_mutex)
  */
-static bool kernfs_unlink_sibling(struct kernfs_node *kn)
+static void 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;
 }
 
 /**
@@ -500,6 +496,7 @@ void kernfs_addrm_finish(struct kernfs_addrm_cxt *acxt)
 
                 acxt->removed = kn->u.removed_list;
 
+                kernfs_unmap_bin_file(kn);
                 kernfs_put(kn);
         }
 }
@@ -857,44 +854,23 @@ static void __kernfs_remove(struct kernfs_addrm_cxt *acxt,
 
         /* unlink the subtree node-by-node */
         do {
-                pos = kernfs_leftmost_descendant(kn);
-
-                /*
-                 * We're gonna release kernfs_mutex to unmap bin files,
-                 * Make sure @pos doesn't go away inbetween.
-                 */
-                kernfs_get(pos);
+                struct kernfs_iattrs *ps_iattr;
 
-                /*
-                 * This must be come before unlinking; otherwise, when
-                 * there are multiple removers, some may finish before
-                 * unmapping is complete.
-                 */
-                if (pos->flags & KERNFS_HAS_MMAP) {
-                        mutex_unlock(&kernfs_mutex);
-                        kernfs_unmap_file(pos);
-                        mutex_lock(&kernfs_mutex);
-                }
+                pos = kernfs_leftmost_descendant(kn);
 
-                /*
-                 * 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;
+                if (pos->parent) {
+                        kernfs_unlink_sibling(pos);
 
                         /* update timestamps on the parent */
+                        ps_iattr = pos->parent->iattr;
                         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);
+                pos->u.removed_list = acxt->removed;
+                acxt->removed = pos;
         } while (pos != kn);
 }
 
diff --git a/fs/kernfs/file.c b/fs/kernfs/file.c
index 404ffd2f27bc..231a171f48b6 100644
--- a/fs/kernfs/file.c
+++ b/fs/kernfs/file.c
@@ -700,11 +700,14 @@ static int kernfs_fop_release(struct inode *inode, struct file *filp)
         return 0;
 }
 
-void kernfs_unmap_file(struct kernfs_node *kn)
+void kernfs_unmap_bin_file(struct kernfs_node *kn)
 {
         struct kernfs_open_node *on;
         struct kernfs_open_file *of;
 
+        if (!(kn->flags & KERNFS_HAS_MMAP))
+                return;
+
         spin_lock_irq(&kernfs_open_node_lock);
         on = kn->attr.open;
         if (on)
diff --git a/fs/kernfs/kernfs-internal.h b/fs/kernfs/kernfs-internal.h
index e9ec38c86074..57a93f4d645c 100644
--- a/fs/kernfs/kernfs-internal.h
+++ b/fs/kernfs/kernfs-internal.h
@@ -113,7 +113,7 @@ struct kernfs_node *kernfs_new_node(struct kernfs_root *root, const char *name,
  */
 extern const struct file_operations kernfs_file_fops;
 
-void kernfs_unmap_file(struct kernfs_node *kn);
+void kernfs_unmap_bin_file(struct kernfs_node *kn);
 
 /*
  * symlink.c