dnotify: report both events on parent and child with single callback

For some events (e.g. DN_ATTRIB on sub-directory) fsnotify may call
dnotify_handle_event() once for watching parent and once again for
the watching sub-directory.

Do the same thing with a single callback instead of two callbacks when
marks iterator contains both inode and child entries.

Link: https://lore.kernel.org/r/20200716084230.30611-12-amir73il@gmail.com
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

diff --git a/fs/notify/dnotify/dnotify.c b/fs/notify/dnotify/dnotify.c
index 2d2eadf..ca78d3f 100644 (file)
--- a/fs/notify/dnotify/dnotify.c
+++ b/fs/notify/dnotify/dnotify.c
@@ -70,26 +70,15 @@ 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 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)
+static void dnotify_one_event(struct fsnotify_group *group, u32 mask,
+                             struct fsnotify_mark *inode_mark)
 {
-       struct fsnotify_mark *inode_mark = fsnotify_iter_inode_mark(iter_info);
        struct dnotify_mark *dn_mark;
        struct dnotify_struct *dn;
        struct dnotify_struct **prev;
        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;
-
-       if (WARN_ON(fsnotify_iter_vfsmount_mark(iter_info)))
-               return 0;
-
        dn_mark = container_of(inode_mark, struct dnotify_mark, fsn_mark);
 
        spin_lock(&inode_mark->lock);
@@ -111,6 +100,33 @@ static int dnotify_handle_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;
 }