6 files changed, 205 insertions, 10 deletions

diff --git a/fs/notify/fsnotify.c b/fs/notify/fsnotify.c
index d5654629c659..7fc760067a62 100644
--- a/fs/notify/fsnotify.c
+++ b/fs/notify/fsnotify.c
@@ -35,6 +35,97 @@ void __fsnotify_inode_delete(struct inode *inode)
 EXPORT_SYMBOL_GPL(__fsnotify_inode_delete);
 
 /*
+ * Given an inode, first check if we care what happens to our children.  Inotify
+ * and dnotify both tell their parents about events.  If we care about any event
+ * on a child we run all of our children and set a dentry flag saying that the
+ * parent cares.  Thus when an event happens on a child it can quickly tell if
+ * if there is a need to find a parent and send the event to the parent.
+ */
+void __fsnotify_update_child_dentry_flags(struct inode *inode)
+{
+        struct dentry *alias;
+        int watched;
+
+        if (!S_ISDIR(inode->i_mode))
+                return;
+
+        /* determine if the children should tell inode about their events */
+        watched = fsnotify_inode_watches_children(inode);
+
+        spin_lock(&dcache_lock);
+        /* run all of the dentries associated with this inode.  Since this is a
+         * directory, there damn well better only be one item on this list */
+        list_for_each_entry(alias, &inode->i_dentry, d_alias) {
+                struct dentry *child;
+
+                /* run all of the children of the original inode and fix their
+                 * d_flags to indicate parental interest (their parent is the
+                 * original inode) */
+                list_for_each_entry(child, &alias->d_subdirs, d_u.d_child) {
+                        if (!child->d_inode)
+                                continue;
+
+                        spin_lock(&child->d_lock);
+                        if (watched)
+                                child->d_flags |= DCACHE_FSNOTIFY_PARENT_WATCHED;
+                        else
+                                child->d_flags &= ~DCACHE_FSNOTIFY_PARENT_WATCHED;
+                        spin_unlock(&child->d_lock);
+                }
+        }
+        spin_unlock(&dcache_lock);
+}
+
+/* Notify this dentry's parent about a child's events. */
+void __fsnotify_parent(struct dentry *dentry, __u32 mask)
+{
+        struct dentry *parent;
+        struct inode *p_inode;
+        bool send = false;
+        bool should_update_children = false;
+
+        if (!(dentry->d_flags & DCACHE_FSNOTIFY_PARENT_WATCHED))
+                return;
+
+        spin_lock(&dentry->d_lock);
+        parent = dentry->d_parent;
+        p_inode = parent->d_inode;
+
+        if (fsnotify_inode_watches_children(p_inode)) {
+                if (p_inode->i_fsnotify_mask & mask) {
+                        dget(parent);
+                        send = true;
+                }
+        } else {
+                /*
+                 * The parent doesn't care about events on it's children but
+                 * at least one child thought it did.  We need to run all the
+                 * children and update their d_flags to let them know p_inode
+                 * doesn't care about them any more.
+                 */
+                dget(parent);
+                should_update_children = true;
+        }
+
+        spin_unlock(&dentry->d_lock);
+
+        if (send) {
+                /* we are notifying a parent so come up with the new mask which
+                 * specifies these are events which came from a child. */
+                mask |= FS_EVENT_ON_CHILD;
+
+                fsnotify(p_inode, mask, dentry->d_inode, FSNOTIFY_EVENT_INODE);
+                dput(parent);
+        }
+
+        if (unlikely(should_update_children)) {
+                __fsnotify_update_child_dentry_flags(p_inode);
+                dput(parent);
+        }
+}
+EXPORT_SYMBOL_GPL(__fsnotify_parent);
+
+/*
  * This is the main call to fsnotify.  The VFS calls into hook specific functions
  * in linux/fsnotify.h.  Those functions then in turn call here.  Here will call
  * out to all of the registered fsnotify_group.  Those groups can then use the
diff --git a/fs/notify/fsnotify.h b/fs/notify/fsnotify.h
index 8ebcbe893c91..83b8ec0a8ec2 100644
--- a/fs/notify/fsnotify.h
+++ b/fs/notify/fsnotify.h
@@ -17,4 +17,9 @@ extern __u32 fsnotify_mask;
 extern void fsnotify_final_destroy_group(struct fsnotify_group *group);
 /* run the list of all marks associated with inode and flag them to be freed */
 extern void fsnotify_clear_marks_by_inode(struct inode *inode);
+/*
+ * update the dentry->d_flags of all of inode's children to indicate if inode cares
+ * about events that happen to its children.
+ */
+extern void __fsnotify_update_child_dentry_flags(struct inode *inode);
 #endif  /* __FS_NOTIFY_FSNOTIFY_H_ */
diff --git a/fs/notify/inode_mark.c b/fs/notify/inode_mark.c
index cdc154146974..a39534845b28 100644
--- a/fs/notify/inode_mark.c
+++ b/fs/notify/inode_mark.c
@@ -131,6 +131,8 @@ void fsnotify_recalc_inode_mask(struct inode *inode)
         spin_lock(&inode->i_lock);
         fsnotify_recalc_inode_mask_locked(inode);
         spin_unlock(&inode->i_lock);
+
+        __fsnotify_update_child_dentry_flags(inode);
 }
 
 /*
@@ -190,6 +192,19 @@ void fsnotify_destroy_mark_by_entry(struct fsnotify_mark_entry *entry)
         group->ops->freeing_mark(entry, group);
 
         /*
+         * __fsnotify_update_child_dentry_flags(inode);
+         *
+         * I really want to call that, but we can't, we have no idea if the inode
+         * still exists the second we drop the entry->lock.
+         *
+         * The next time an event arrive to this inode from one of it's children
+         * __fsnotify_parent will see that the inode doesn't care about it's
+         * children and will update all of these flags then.  So really this
+         * is just a lazy update (and could be a perf win...)
+         */
+
+
+        /*
          * it's possible that this group tried to destroy itself, but this
          * this mark was simultaneously being freed by inode.  If that's the
          * case, we finish freeing the group here.
@@ -323,6 +338,8 @@ int fsnotify_add_mark(struct fsnotify_mark_entry *entry,
         if (lentry) {
                 ret = -EEXIST;
                 fsnotify_put_mark(lentry);
+        } else {
+                __fsnotify_update_child_dentry_flags(inode);
         }
 
         return ret;
diff --git a/include/linux/dcache.h b/include/linux/dcache.h
index 15156364d196..97978004338d 100644
--- a/include/linux/dcache.h
+++ b/include/linux/dcache.h
@@ -180,10 +180,12 @@ d_iput:		no		no		no       yes
 #define DCACHE_REFERENCED       0x0008  /* Recently used, don't discard. */
 #define DCACHE_UNHASHED         0x0010  
 
-#define DCACHE_INOTIFY_PARENT_WATCHED   0x0020 /* Parent inode is watched */
+#define DCACHE_INOTIFY_PARENT_WATCHED   0x0020 /* Parent inode is watched by inotify */
 
 #define DCACHE_COOKIE           0x0040  /* For use by dcookie subsystem */
 
+#define DCACHE_FSNOTIFY_PARENT_WATCHED  0x0080 /* Parent inode is watched by some fsnotify listener */
+
 extern spinlock_t dcache_lock;
 extern seqlock_t rename_lock;
 
diff --git a/include/linux/fsnotify.h b/include/linux/fsnotify.h
index 3856eb6e5973..6a662ed0bc8a 100644
--- a/include/linux/fsnotify.h
+++ b/include/linux/fsnotify.h
@@ -23,15 +23,31 @@
 static inline void fsnotify_d_instantiate(struct dentry *entry,
                                                 struct inode *inode)
 {
+        __fsnotify_d_instantiate(entry, inode);
+
         inotify_d_instantiate(entry, inode);
 }
 
+/* Notify this dentry's parent about a child's events. */
+static inline void fsnotify_parent(struct dentry *dentry, __u32 mask)
+{
+        __fsnotify_parent(dentry, mask);
+
+        inotify_dentry_parent_queue_event(dentry, mask, 0, dentry->d_name.name);
+}
+
 /*
  * fsnotify_d_move - entry has been moved
  * Called with dcache_lock and entry->d_lock held.
  */
 static inline void fsnotify_d_move(struct dentry *entry)
 {
+        /*
+         * On move we need to update entry->d_flags to indicate if the new parent
+         * cares about events from this entry.
+         */
+        __fsnotify_update_dcache_flags(entry);
+
         inotify_d_move(entry);
 }
 
@@ -117,7 +133,8 @@ static inline void fsnotify_nameremove(struct dentry *dentry, int isdir)
         if (isdir)
                 mask |= FS_IN_ISDIR;
         dnotify_parent(dentry, DN_DELETE);
-        inotify_dentry_parent_queue_event(dentry, mask, 0, dentry->d_name.name);
+
+        fsnotify_parent(dentry, mask);
 }
 
 /*
@@ -188,9 +205,9 @@ static inline void fsnotify_access(struct dentry *dentry)
                 mask |= FS_IN_ISDIR;
 
         dnotify_parent(dentry, DN_ACCESS);
-        inotify_dentry_parent_queue_event(dentry, mask, 0, dentry->d_name.name);
         inotify_inode_queue_event(inode, mask, 0, NULL, NULL);
 
+        fsnotify_parent(dentry, mask);
         fsnotify(inode, mask, inode, FSNOTIFY_EVENT_INODE);
 }
 
@@ -206,9 +223,9 @@ static inline void fsnotify_modify(struct dentry *dentry)
                 mask |= FS_IN_ISDIR;
 
         dnotify_parent(dentry, DN_MODIFY);
-        inotify_dentry_parent_queue_event(dentry, mask, 0, dentry->d_name.name);
         inotify_inode_queue_event(inode, mask, 0, NULL, NULL);
 
+        fsnotify_parent(dentry, mask);
         fsnotify(inode, mask, inode, FSNOTIFY_EVENT_INODE);
 }
 
@@ -223,9 +240,9 @@ static inline void fsnotify_open(struct dentry *dentry)
         if (S_ISDIR(inode->i_mode))
                 mask |= FS_IN_ISDIR;
 
-        inotify_dentry_parent_queue_event(dentry, mask, 0, dentry->d_name.name);
         inotify_inode_queue_event(inode, mask, 0, NULL, NULL);
 
+        fsnotify_parent(dentry, mask);
         fsnotify(inode, mask, inode, FSNOTIFY_EVENT_INODE);
 }
 
@@ -236,16 +253,15 @@ static inline void fsnotify_close(struct file *file)
 {
         struct dentry *dentry = file->f_path.dentry;
         struct inode *inode = dentry->d_inode;
-        const char *name = dentry->d_name.name;
         fmode_t mode = file->f_mode;
         __u32 mask = (mode & FMODE_WRITE) ? FS_CLOSE_WRITE : FS_CLOSE_NOWRITE;
 
         if (S_ISDIR(inode->i_mode))
                 mask |= FS_IN_ISDIR;
 
-        inotify_dentry_parent_queue_event(dentry, mask, 0, name);
         inotify_inode_queue_event(inode, mask, 0, NULL, NULL);
 
+        fsnotify_parent(dentry, mask);
         fsnotify(inode, mask, file, FSNOTIFY_EVENT_FILE);
 }
 
@@ -260,9 +276,9 @@ static inline void fsnotify_xattr(struct dentry *dentry)
         if (S_ISDIR(inode->i_mode))
                 mask |= FS_IN_ISDIR;
 
-        inotify_dentry_parent_queue_event(dentry, mask, 0, dentry->d_name.name);
         inotify_inode_queue_event(inode, mask, 0, NULL, NULL);
 
+        fsnotify_parent(dentry, mask);
         fsnotify(inode, mask, inode, FSNOTIFY_EVENT_INODE);
 }
 
@@ -311,8 +327,8 @@ static inline void fsnotify_change(struct dentry *dentry, unsigned int ia_valid)
                 if (S_ISDIR(inode->i_mode))
                         in_mask |= FS_IN_ISDIR;
                 inotify_inode_queue_event(inode, in_mask, 0, NULL, NULL);
-                inotify_dentry_parent_queue_event(dentry, in_mask, 0,
-                                                  dentry->d_name.name);
+
+                fsnotify_parent(dentry, in_mask);
                 fsnotify(inode, in_mask, inode, FSNOTIFY_EVENT_INODE);
         }
 }
diff --git a/include/linux/fsnotify_backend.h b/include/linux/fsnotify_backend.h
index cad5c4d75c1d..13d2dd570049 100644
--- a/include/linux/fsnotify_backend.h
+++ b/include/linux/fsnotify_backend.h
@@ -46,6 +46,17 @@
 #define FS_DN_RENAME            0x10000000      /* file renamed */
 #define FS_DN_MULTISHOT         0x20000000      /* dnotify multishot */
 
+/* This inode cares about things that happen to its children.  Always set for
+ * dnotify and inotify. */
+#define FS_EVENT_ON_CHILD       0x08000000
+
+/* This is a list of all events that may get sent to a parernt based on fs event
+ * happening to inodes inside that directory */
+#define FS_EVENTS_POSS_ON_CHILD   (FS_ACCESS | FS_MODIFY | FS_ATTRIB |\
+                                   FS_CLOSE_WRITE | FS_CLOSE_NOWRITE | FS_OPEN |\
+                                   FS_MOVED_FROM | FS_MOVED_TO | FS_CREATE |\
+                                   FS_DELETE)
+
 struct fsnotify_group;
 struct fsnotify_event;
 struct fsnotify_mark_entry;
@@ -183,8 +194,52 @@ struct fsnotify_mark_entry {
 
 /* main fsnotify call to send events */
 extern void fsnotify(struct inode *to_tell, __u32 mask, void *data, int data_is);
+extern void __fsnotify_parent(struct dentry *dentry, __u32 mask);
 extern void __fsnotify_inode_delete(struct inode *inode);
 
+static inline int fsnotify_inode_watches_children(struct inode *inode)
+{
+        /* FS_EVENT_ON_CHILD is set if the inode may care */
+        if (!(inode->i_fsnotify_mask & FS_EVENT_ON_CHILD))
+                return 0;
+        /* this inode might care about child events, does it care about the
+         * specific set of events that can happen on a child? */
+        return inode->i_fsnotify_mask & FS_EVENTS_POSS_ON_CHILD;
+}
+
+/*
+ * Update the dentry with a flag indicating the interest of its parent to receive
+ * filesystem events when those events happens to this dentry->d_inode.
+ */
+static inline void __fsnotify_update_dcache_flags(struct dentry *dentry)
+{
+        struct dentry *parent;
+
+        assert_spin_locked(&dcache_lock);
+        assert_spin_locked(&dentry->d_lock);
+
+        parent = dentry->d_parent;
+        if (fsnotify_inode_watches_children(parent->d_inode))
+                dentry->d_flags |= DCACHE_FSNOTIFY_PARENT_WATCHED;
+        else
+                dentry->d_flags &= ~DCACHE_FSNOTIFY_PARENT_WATCHED;
+}
+
+/*
+ * fsnotify_d_instantiate - instantiate a dentry for inode
+ * Called with dcache_lock held.
+ */
+static inline void __fsnotify_d_instantiate(struct dentry *dentry, struct inode *inode)
+{
+        if (!inode)
+                return;
+
+        assert_spin_locked(&dcache_lock);
+
+        spin_lock(&dentry->d_lock);
+        __fsnotify_update_dcache_flags(dentry);
+        spin_unlock(&dentry->d_lock);
+}
 
 /* called from fsnotify listeners, such as fanotify or dnotify */
 
@@ -230,9 +285,18 @@ extern struct fsnotify_event *fsnotify_create_event(struct inode *to_tell, __u32
 static inline void fsnotify(struct inode *to_tell, __u32 mask, void *data, int data_is)
 {}
 
+static inline void __fsnotify_parent(struct dentry *dentry, __u32 mask)
+{}
+
 static inline void __fsnotify_inode_delete(struct inode *inode)
 {}
 
+static inline void __fsnotify_update_dcache_flags(struct dentry *dentry)
+{}
+
+static inline void __fsnotify_d_instantiate(struct dentry *dentry, struct inode *inode)
+{}
+
 #endif  /* CONFIG_FSNOTIFY */
 
 #endif  /* __KERNEL __ */