Merge tag 'fsnotify_for_v5.2-rc1' of ssh://gitolite.kernel.org/pub/sc…

…m/linux/kernel/git/jack/linux-fs

Pull fsnotify fixes from Jan Kara:
 "Two fsnotify fixes"

* tag 'fsnotify_for_v5.2-rc1' of ssh://gitolite.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs:
  fsnotify: fix unlink performance regression
  fsnotify: Clarify connector assignment in fsnotify_add_mark_list()

fs/notify/fsnotify.c

@@ -107,6 +107,47 @@ void fsnotify_sb_delete(struct super_block *sb)
 	fsnotify_clear_marks_by_sb(sb);
 }
 
+/*
+ * fsnotify_nameremove - a filename was removed from a directory
+ *
+ * This is mostly called under parent vfs inode lock so name and
+ * dentry->d_parent should be stable. However there are some corner cases where
+ * inode lock is not held. So to be on the safe side and be reselient to future
+ * callers and out of tree users of d_delete(), we do not assume that d_parent
+ * and d_name are stable and we use dget_parent() and
+ * take_dentry_name_snapshot() to grab stable references.
+ */
+void fsnotify_nameremove(struct dentry *dentry, int isdir)
+{
+	struct dentry *parent;
+	struct name_snapshot name;
+	__u32 mask = FS_DELETE;
+
+	/* d_delete() of pseudo inode? (e.g. __ns_get_path() playing tricks) */
+	if (IS_ROOT(dentry))
+		return;
+
+	if (isdir)
+		mask |= FS_ISDIR;
+
+	parent = dget_parent(dentry);
+	/* Avoid unneeded take_dentry_name_snapshot() */
+	if (!(d_inode(parent)->i_fsnotify_mask & FS_DELETE) &&
+	    !(dentry->d_sb->s_fsnotify_mask & FS_DELETE))
+		goto out_dput;
+
+	take_dentry_name_snapshot(&name, dentry);
+
+	fsnotify(d_inode(parent), mask, d_inode(dentry), FSNOTIFY_EVENT_INODE,
+		 &name.name, 0);
+
+	release_dentry_name_snapshot(&name);
+
+out_dput:
+	dput(parent);
+}
+EXPORT_SYMBOL(fsnotify_nameremove);
+
 /*
  * 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

fs/notify/mark.c

@@ -619,6 +619,11 @@ static int fsnotify_add_mark_list(struct fsnotify_mark *mark,
 	/* mark should be the last entry.  last is the current last entry */
 	hlist_add_behind_rcu(&mark->obj_list, &last->obj_list);
 added:
+	/*
+	 * Since connector is attached to object using cmpxchg() we are
+	 * guaranteed that connector initialization is fully visible by anyone
+	 * seeing mark->connector set.
+	 */
 	WRITE_ONCE(mark->connector, conn);
 out_err:
 	spin_unlock(&conn->lock);

include/linux/fsnotify.h

@@ -151,39 +151,6 @@ static inline void fsnotify_vfsmount_delete(struct vfsmount *mnt)
 	__fsnotify_vfsmount_delete(mnt);
 }
 
-/*
- * fsnotify_nameremove - a filename was removed from a directory
- *
- * This is mostly called under parent vfs inode lock so name and
- * dentry->d_parent should be stable. However there are some corner cases where
- * inode lock is not held. So to be on the safe side and be reselient to future
- * callers and out of tree users of d_delete(), we do not assume that d_parent
- * and d_name are stable and we use dget_parent() and
- * take_dentry_name_snapshot() to grab stable references.
- */
-static inline void fsnotify_nameremove(struct dentry *dentry, int isdir)
-{
-	struct dentry *parent;
-	struct name_snapshot name;
-	__u32 mask = FS_DELETE;
-
-	/* d_delete() of pseudo inode? (e.g. __ns_get_path() playing tricks) */
-	if (IS_ROOT(dentry))
-		return;
-
-	if (isdir)
-		mask |= FS_ISDIR;
-
-	parent = dget_parent(dentry);
-	take_dentry_name_snapshot(&name, dentry);
-
-	fsnotify(d_inode(parent), mask, d_inode(dentry), FSNOTIFY_EVENT_INODE,
-		 &name.name, 0);
-
-	release_dentry_name_snapshot(&name);
-	dput(parent);
-}
-
 /*
  * fsnotify_inoderemove - an inode is going away
  */

include/linux/fsnotify_backend.h

@@ -355,6 +355,7 @@ extern int __fsnotify_parent(const struct path *path, struct dentry *dentry, __u
 extern void __fsnotify_inode_delete(struct inode *inode);
 extern void __fsnotify_vfsmount_delete(struct vfsmount *mnt);
 extern void fsnotify_sb_delete(struct super_block *sb);
+extern void fsnotify_nameremove(struct dentry *dentry, int isdir);
 extern u32 fsnotify_get_cookie(void);
 
 static inline int fsnotify_inode_watches_children(struct inode *inode)
@@ -524,6 +525,9 @@ static inline void __fsnotify_vfsmount_delete(struct vfsmount *mnt)
 static inline void fsnotify_sb_delete(struct super_block *sb)
 {}
 
+static inline void fsnotify_nameremove(struct dentry *dentry, int isdir)
+{}
+
 static inline void fsnotify_update_flags(struct dentry *dentry)
 {}