fsnotify: introduce locked versions of fsnotify_add_mark() and fsnotify_remove_mark()

This patch introduces fsnotify_add_mark_locked() and fsnotify_remove_mark_locked()
which are essentially the same as fsnotify_add_mark() and fsnotify_remove_mark() but
assume that the caller has already taken the groups mark mutex.

Signed-off-by: Lino Sanfilippo <LinoSanfilippo@gmx.de>
Signed-off-by: Eric Paris <eparis@redhat.com>

1 files changed, 30 insertions, 12 deletions

diff --git a/fs/notify/mark.c b/fs/notify/mark.c
index b77c833c8d0a..f9dda0304a10 100644
--- a/fs/notify/mark.c
+++ b/fs/notify/mark.c
@@ -121,18 +121,18 @@ void fsnotify_put_mark(struct fsnotify_mark *mark)
  * The caller had better be holding a reference to this mark so we don't actually
  * do the final put under the mark->lock
  */
-void fsnotify_destroy_mark(struct fsnotify_mark *mark,
-                           struct fsnotify_group *group)
+void fsnotify_destroy_mark_locked(struct fsnotify_mark *mark,
+                                  struct fsnotify_group *group)
 {
         struct inode *inode = NULL;
 
-        mutex_lock(&group->mark_mutex);
+        BUG_ON(!mutex_is_locked(&group->mark_mutex));
+
         spin_lock(&mark->lock);
 
         /* something else already called this function on this mark */
         if (!(mark->flags & FSNOTIFY_MARK_FLAG_ALIVE)) {
                 spin_unlock(&mark->lock);
-                mutex_unlock(&group->mark_mutex);
                 return;
         }
 
@@ -149,6 +149,8 @@ void fsnotify_destroy_mark(struct fsnotify_mark *mark,
         list_del_init(&mark->g_list);
 
         spin_unlock(&mark->lock);
+
+        /* release lock temporarily */
         mutex_unlock(&group->mark_mutex);
 
         spin_lock(&destroy_lock);
@@ -184,6 +186,16 @@ void fsnotify_destroy_mark(struct fsnotify_mark *mark,
          */
 
         atomic_dec(&group->num_marks);
+
+        mutex_lock(&group->mark_mutex);
+}
+
+void fsnotify_destroy_mark(struct fsnotify_mark *mark,
+                           struct fsnotify_group *group)
+{
+        mutex_lock(&group->mark_mutex);
+        fsnotify_destroy_mark_locked(mark, group);
+        mutex_unlock(&group->mark_mutex);
 }
 
 void fsnotify_set_mark_mask_locked(struct fsnotify_mark *mark, __u32 mask)
@@ -208,14 +220,15 @@ void fsnotify_set_mark_ignored_mask_locked(struct fsnotify_mark *mark, __u32 mas
  * These marks may be used for the fsnotify backend to determine which
  * event types should be delivered to which group.
  */
-int fsnotify_add_mark(struct fsnotify_mark *mark,
-                      struct fsnotify_group *group, struct inode *inode,
-                      struct vfsmount *mnt, int allow_dups)
+int fsnotify_add_mark_locked(struct fsnotify_mark *mark,
+                             struct fsnotify_group *group, struct inode *inode,
+                             struct vfsmount *mnt, int allow_dups)
 {
         int ret = 0;
 
         BUG_ON(inode && mnt);
         BUG_ON(!inode && !mnt);
+        BUG_ON(!mutex_is_locked(&group->mark_mutex));
 
         /*
          * LOCKING ORDER!!!!
@@ -223,8 +236,6 @@ int fsnotify_add_mark(struct fsnotify_mark *mark,
          * mark->lock
          * inode->i_lock
          */
-        mutex_lock(&group->mark_mutex);
-
         spin_lock(&mark->lock);
         mark->flags |= FSNOTIFY_MARK_FLAG_ALIVE;
 
@@ -250,8 +261,6 @@ int fsnotify_add_mark(struct fsnotify_mark *mark,
         fsnotify_set_mark_mask_locked(mark, mark->mask);
         spin_unlock(&mark->lock);
 
-        mutex_unlock(&group->mark_mutex);
-
         if (inode)
                 __fsnotify_update_child_dentry_flags(inode);
 
@@ -264,7 +273,6 @@ err:
         atomic_dec(&group->num_marks);
 
         spin_unlock(&mark->lock);
-        mutex_unlock(&group->mark_mutex);
 
         spin_lock(&destroy_lock);
         list_add(&mark->destroy_list, &destroy_list);
@@ -274,6 +282,16 @@ err:
         return ret;
 }
 
+int fsnotify_add_mark(struct fsnotify_mark *mark, struct fsnotify_group *group,
+                      struct inode *inode, struct vfsmount *mnt, int allow_dups)
+{
+        int ret;
+        mutex_lock(&group->mark_mutex);
+        ret = fsnotify_add_mark_locked(mark, group, inode, mnt, allow_dups);
+        mutex_unlock(&group->mark_mutex);
+        return ret;
+}
+
 /*
  * clear any marks in a group in which mark->flags & flags is true
  */