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>

2 files changed, 58 insertions, 32 deletions

diff --git a/fs/notify/dnotify/dnotify.c b/fs/notify/dnotify/dnotify.c
index ca78d3f78da8..5dcda8f20c04 100644
--- a/fs/notify/dnotify/dnotify.c
+++ b/fs/notify/dnotify/dnotify.c
@@ -70,8 +70,9 @@ static void dnotify_recalc_inode_mask(struct fsnotify_mark *fsn_mark)
  * destroy the dnotify struct if it was not registered to receive multiple
  * events.
  */
-static void dnotify_one_event(struct fsnotify_group *group, u32 mask,
-			      struct fsnotify_mark *inode_mark)
+static int dnotify_handle_event(struct fsnotify_mark *inode_mark, u32 mask,
+				struct inode *inode, struct inode *dir,
+				const struct qstr *name)
 {
 	struct dnotify_mark *dn_mark;
 	struct dnotify_struct *dn;
@@ -79,6 +80,10 @@ static void dnotify_one_event(struct fsnotify_group *group, u32 mask,
 	struct fown_struct *fown;
 	__u32 test_mask = mask & ~FS_EVENT_ON_CHILD;
 
+	/* not a dir, dnotify doesn't care */
+	if (!dir && !(mask & FS_ISDIR))
+		return 0;
+
 	dn_mark = container_of(inode_mark, struct dnotify_mark, fsn_mark);
 
 	spin_lock(&inode_mark->lock);
@@ -100,33 +105,6 @@ static void dnotify_one_event(struct fsnotify_group *group, u32 mask,
 	}
 
 	spin_unlock(&inode_mark->lock);
-}
-
-static int dnotify_handle_event(struct fsnotify_group *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)
-{
-	struct fsnotify_mark *inode_mark = fsnotify_iter_inode_mark(iter_info);
-	struct fsnotify_mark *child_mark = fsnotify_iter_child_mark(iter_info);
-
-	/* not a dir, dnotify doesn't care */
-	if (!dir && !(mask & FS_ISDIR))
-		return 0;
-
-	if (WARN_ON(fsnotify_iter_vfsmount_mark(iter_info)))
-		return 0;
-
-	/*
-	 * Some events can be sent on both parent dir and subdir marks
-	 * (e.g. DN_ATTRIB).  If both parent dir and subdir are watching,
-	 * report the event once to parent dir and once to subdir.
-	 */
-	if (inode_mark)
-		dnotify_one_event(group, mask, inode_mark);
-	if (child_mark)
-		dnotify_one_event(group, mask, child_mark);
 
 	return 0;
 }
@@ -143,7 +121,7 @@ static void dnotify_free_mark(struct fsnotify_mark *fsn_mark)
 }
 
 static const struct fsnotify_ops dnotify_fsnotify_ops = {
-	.handle_event = dnotify_handle_event,
+	.handle_inode_event = dnotify_handle_event,
 	.free_mark = dnotify_free_mark,
 };
 
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)