fsnotify: create method handle_inode_event() in fsnotify_operations

The method handle_event() grew a lot of complexity due to the design of
fanotify and merging of ignore masks.

Most backends do not care about this complex functionality, so we can hide
this complexity from them.

Introduce a method handle_inode_event() that serves those backends and
passes a single inode mark and less arguments.

This change converts all backends except fanotify and inotify to use the
simplified handle_inode_event() method.  In pricipal, inotify could have
also used the new method, but that would require passing more arguments
on the simple helper (data, data_type, cookie), so we leave it with the
handle_event() method.

Link: https://lore.kernel.org/r/20200722125849.17418-9-amir73il@gmail.com
Suggested-by: Jan Kara <jack@suse.cz>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

1 files changed, 50 insertions, 2 deletions

diff --git a/fs/notify/fsnotify.c b/fs/notify/fsnotify.c
index 494d5d70323f..a960ec3a569a 100644
--- a/fs/notify/fsnotify.c
+++ b/fs/notify/fsnotify.c
@@ -230,6 +230,49 @@ notify:
 }
 EXPORT_SYMBOL_GPL(__fsnotify_parent);
 
+static int fsnotify_handle_event(struct fsnotify_group *group, __u32 mask,
+				 const void *data, int data_type,
+				 struct inode *dir, const struct qstr *name,
+				 u32 cookie, struct fsnotify_iter_info *iter_info)
+{
+	struct fsnotify_mark *inode_mark = fsnotify_iter_inode_mark(iter_info);
+	struct fsnotify_mark *child_mark = fsnotify_iter_child_mark(iter_info);
+	struct inode *inode = fsnotify_data_inode(data, data_type);
+	const struct fsnotify_ops *ops = group->ops;
+	int ret;
+
+	if (WARN_ON_ONCE(!ops->handle_inode_event))
+		return 0;
+
+	if (WARN_ON_ONCE(fsnotify_iter_sb_mark(iter_info)) ||
+	    WARN_ON_ONCE(fsnotify_iter_vfsmount_mark(iter_info)))
+		return 0;
+
+	/*
+	 * An event can be sent on child mark iterator instead of inode mark
+	 * iterator because of other groups that have interest of this inode
+	 * and have marks on both parent and child.  We can simplify this case.
+	 */
+	if (!inode_mark) {
+		inode_mark = child_mark;
+		child_mark = NULL;
+		dir = NULL;
+		name = NULL;
+	}
+
+	ret = ops->handle_inode_event(inode_mark, mask, inode, dir, name);
+	if (ret || !child_mark)
+		return ret;
+
+	/*
+	 * Some events can be sent on both parent dir and child marks
+	 * (e.g. FS_ATTRIB).  If both parent dir and child are watching,
+	 * report the event once to parent dir with name and once to child
+	 * without name.
+	 */
+	return ops->handle_inode_event(child_mark, mask, inode, NULL, NULL);
+}
+
 static int send_to_group(__u32 mask, const void *data, int data_type,
 			 struct inode *dir, const struct qstr *file_name,
 			 u32 cookie, struct fsnotify_iter_info *iter_info)
@@ -275,8 +318,13 @@ static int send_to_group(__u32 mask, const void *data, int data_type,
 	if (!(test_mask & marks_mask & ~marks_ignored_mask))
 		return 0;
 
-	return group->ops->handle_event(group, mask, data, data_type, dir,
-					file_name, cookie, iter_info);
+	if (group->ops->handle_event) {
+		return group->ops->handle_event(group, mask, data, data_type, dir,
+						file_name, cookie, iter_info);
+	}
+
+	return fsnotify_handle_event(group, mask, data, data_type, dir,
+				     file_name, cookie, iter_info);
 }
 
 static struct fsnotify_mark *fsnotify_first_mark(struct fsnotify_mark_connector **connp)