1 files changed, 37 insertions, 173 deletions

diff --git a/fs/notify/group.c b/fs/notify/group.c
index 0e1677144bc..ad199598045 100644
--- a/fs/notify/group.c
+++ b/fs/notify/group.c
@@ -26,74 +26,13 @@
 #include <linux/fsnotify_backend.h>
 #include "fsnotify.h"
 
-#include <asm/atomic.h>
-
-/* protects writes to fsnotify_groups and fsnotify_mask */
-static DEFINE_MUTEX(fsnotify_grp_mutex);
-/* protects reads while running the fsnotify_groups list */
-struct srcu_struct fsnotify_grp_srcu;
-/* all groups registered to receive filesystem notifications */
-LIST_HEAD(fsnotify_groups);
-/* bitwise OR of all events (FS_*) interesting to some group on this system */
-__u32 fsnotify_mask;
-
-/*
- * When a new group registers or changes it's set of interesting events
- * this function updates the fsnotify_mask to contain all interesting events
- */
-void fsnotify_recalc_global_mask(void)
-{
-	struct fsnotify_group *group;
-	__u32 mask = 0;
-	int idx;
-
-	idx = srcu_read_lock(&fsnotify_grp_srcu);
-	list_for_each_entry_rcu(group, &fsnotify_groups, group_list)
-		mask |= group->mask;
-	srcu_read_unlock(&fsnotify_grp_srcu, idx);
-	fsnotify_mask = mask;
-}
-
-/*
- * Update the group->mask by running all of the marks associated with this
- * group and finding the bitwise | of all of the mark->mask.  If we change
- * the group->mask we need to update the global mask of events interesting
- * to the system.
- */
-void fsnotify_recalc_group_mask(struct fsnotify_group *group)
-{
-	__u32 mask = 0;
-	__u32 old_mask = group->mask;
-	struct fsnotify_mark_entry *entry;
-
-	spin_lock(&group->mark_lock);
-	list_for_each_entry(entry, &group->mark_entries, g_list)
-		mask |= entry->mask;
-	spin_unlock(&group->mark_lock);
-
-	group->mask = mask;
-
-	if (old_mask != mask)
-		fsnotify_recalc_global_mask();
-}
-
-/*
- * Take a reference to a group so things found under the fsnotify_grp_mutex
- * can't get freed under us
- */
-static void fsnotify_get_group(struct fsnotify_group *group)
-{
-	atomic_inc(&group->refcnt);
-}
+#include <linux/atomic.h>
 
 /*
  * Final freeing of a group
  */
 void fsnotify_final_destroy_group(struct fsnotify_group *group)
 {
-	/* clear the notification queue of all events */
-	fsnotify_flush_notify(group);
-
 	if (group->ops->free_group_priv)
 		group->ops->free_group_priv(group);
 
@@ -101,47 +40,37 @@ void fsnotify_final_destroy_group(struct fsnotify_group *group)
 }
 
 /*
- * Trying to get rid of a group.  We need to first get rid of any outstanding
- * allocations and then free the group.  Remember that fsnotify_clear_marks_by_group
- * could miss marks that are being freed by inode and those marks could still
- * hold a reference to this group (via group->num_marks)  If we get into that
- * situtation, the fsnotify_final_destroy_group will get called when that final
- * mark is freed.
+ * Trying to get rid of a group. Remove all marks, flush all events and release
+ * the group reference.
+ * Note that another thread calling fsnotify_clear_marks_by_group() may still
+ * hold a ref to the group.
  */
-static void fsnotify_destroy_group(struct fsnotify_group *group)
+void fsnotify_destroy_group(struct fsnotify_group *group)
 {
-	/* clear all inode mark entries for this group */
+	/* clear all inode marks for this group */
 	fsnotify_clear_marks_by_group(group);
 
-	/* past the point of no return, matches the initial value of 1 */
-	if (atomic_dec_and_test(&group->num_marks))
-		fsnotify_final_destroy_group(group);
-}
+	synchronize_srcu(&fsnotify_mark_srcu);
 
-/*
- * Remove this group from the global list of groups that will get events
- * this can be done even if there are still references and things still using
- * this group.  This just stops the group from getting new events.
- */
-static void __fsnotify_evict_group(struct fsnotify_group *group)
-{
-	BUG_ON(!mutex_is_locked(&fsnotify_grp_mutex));
+	/* clear the notification queue of all events */
+	fsnotify_flush_notify(group);
+
+	/*
+	 * Destroy overflow event (we cannot use fsnotify_destroy_event() as
+	 * that deliberately ignores overflow events.
+	 */
+	if (group->overflow_event)
+		group->ops->free_event(group->overflow_event);
 
-	if (group->on_group_list)
-		list_del_rcu(&group->group_list);
-	group->on_group_list = 0;
+	fsnotify_put_group(group);
 }
 
 /*
- * Called when a group is no longer interested in getting events.  This can be
- * used if a group is misbehaving or if for some reason a group should no longer
- * get any filesystem events.
+ * Get reference to a group.
  */
-void fsnotify_evict_group(struct fsnotify_group *group)
+void fsnotify_get_group(struct fsnotify_group *group)
 {
-	mutex_lock(&fsnotify_grp_mutex);
-	__fsnotify_evict_group(group);
-	mutex_unlock(&fsnotify_grp_mutex);
+	atomic_inc(&group->refcnt);
 }
 
 /*
@@ -149,106 +78,41 @@ void fsnotify_evict_group(struct fsnotify_group *group)
  */
 void fsnotify_put_group(struct fsnotify_group *group)
 {
-	if (!atomic_dec_and_mutex_lock(&group->refcnt, &fsnotify_grp_mutex))
-		return;
-
-	/*
-	 * OK, now we know that there's no other users *and* we hold mutex,
-	 * so no new references will appear
-	 */
-	__fsnotify_evict_group(group);
-
-	/*
-	 * now it's off the list, so the only thing we might care about is
-	 * srcu access....
-	 */
-	mutex_unlock(&fsnotify_grp_mutex);
-	synchronize_srcu(&fsnotify_grp_srcu);
-
-	/* and now it is really dead. _Nothing_ could be seeing it */
-	fsnotify_recalc_global_mask();
-	fsnotify_destroy_group(group);
-}
-
-/*
- * Simply run the fsnotify_groups list and find a group which matches
- * the given parameters.  If a group is found we take a reference to that
- * group.
- */
-static struct fsnotify_group *fsnotify_find_group(unsigned int group_num, __u32 mask,
-						  const struct fsnotify_ops *ops)
-{
-	struct fsnotify_group *group_iter;
-	struct fsnotify_group *group = NULL;
-
-	BUG_ON(!mutex_is_locked(&fsnotify_grp_mutex));
-
-	list_for_each_entry_rcu(group_iter, &fsnotify_groups, group_list) {
-		if (group_iter->group_num == group_num) {
-			if ((group_iter->mask == mask) &&
-			    (group_iter->ops == ops)) {
-				fsnotify_get_group(group_iter);
-				group = group_iter;
-			} else
-				group = ERR_PTR(-EEXIST);
-		}
-	}
-	return group;
+	if (atomic_dec_and_test(&group->refcnt))
+		fsnotify_final_destroy_group(group);
 }
 
 /*
- * Either finds an existing group which matches the group_num, mask, and ops or
- * creates a new group and adds it to the global group list.  In either case we
- * take a reference for the group returned.
+ * Create a new fsnotify_group and hold a reference for the group returned.
  */
-struct fsnotify_group *fsnotify_obtain_group(unsigned int group_num, __u32 mask,
-					     const struct fsnotify_ops *ops)
+struct fsnotify_group *fsnotify_alloc_group(const struct fsnotify_ops *ops)
 {
-	struct fsnotify_group *group, *tgroup;
+	struct fsnotify_group *group;
 
-	/* very low use, simpler locking if we just always alloc */
-	group = kmalloc(sizeof(struct fsnotify_group), GFP_KERNEL);
+	group = kzalloc(sizeof(struct fsnotify_group), GFP_KERNEL);
 	if (!group)
 		return ERR_PTR(-ENOMEM);
 
+	/* set to 0 when there a no external references to this group */
 	atomic_set(&group->refcnt, 1);
-
-	group->on_group_list = 0;
-	group->group_num = group_num;
-	group->mask = mask;
+	atomic_set(&group->num_marks, 0);
 
 	mutex_init(&group->notification_mutex);
 	INIT_LIST_HEAD(&group->notification_list);
 	init_waitqueue_head(&group->notification_waitq);
-	group->q_len = 0;
 	group->max_events = UINT_MAX;
 
-	spin_lock_init(&group->mark_lock);
-	atomic_set(&group->num_marks, 0);
-	INIT_LIST_HEAD(&group->mark_entries);
+	mutex_init(&group->mark_mutex);
+	INIT_LIST_HEAD(&group->marks_list);
 
 	group->ops = ops;
 
-	mutex_lock(&fsnotify_grp_mutex);
-	tgroup = fsnotify_find_group(group_num, mask, ops);
-	if (tgroup) {
-		/* group already exists */
-		mutex_unlock(&fsnotify_grp_mutex);
-		/* destroy the new one we made */
-		fsnotify_put_group(group);
-		return tgroup;
-	}
-
-	/* group not found, add a new one */
-	list_add_rcu(&group->group_list, &fsnotify_groups);
-	group->on_group_list = 1;
-	/* being on the fsnotify_groups list holds one num_marks */
-	atomic_inc(&group->num_marks);
-
-	mutex_unlock(&fsnotify_grp_mutex);
+	return group;
+}
 
-	if (mask)
-		fsnotify_recalc_global_mask();
+int fsnotify_fasync(int fd, struct file *file, int on)
+{
+	struct fsnotify_group *group = file->private_data;
 
-	return group;
+	return fasync_helper(fd, file, on, &group->fsn_fa) >= 0 ? 0 : -EIO;
 }