fsnotify: allow marks to not pin inodes in core

inotify marks must pin inodes in core.  dnotify doesn't technically need to
since they are closed when the directory is closed.  fanotify also need to
pin inodes in core as it works today.  But the next step is to introduce
the concept of 'ignored masks' which is actually a mask of events for an
inode of no interest.  I claim that these should be liberally sent to the
kernel and should not pin the inode in core.  If the inode is brought back
in the listener will get an event it may have thought excluded, but this is
not a serious situation and one any listener should deal with.

This patch lays the ground work for non-pinning inode marks by using lazy
inode pinning.  We do not pin a mark until it has a non-zero mask entry.  If a
listener new sets a mask we never pin the inode.

Signed-off-by: Eric Paris <eparis@redhat.com>

1 files changed, 2 insertions, 2 deletions

diff --git a/fs/notify/fanotify/fanotify_user.c b/fs/notify/fanotify/fanotify_user.c
index 84155841a025..3320f0c57e31 100644
--- a/fs/notify/fanotify/fanotify_user.c
+++ b/fs/notify/fanotify/fanotify_user.c
@@ -302,7 +302,7 @@ static __u32 fanotify_mark_remove_from_mask(struct fsnotify_mark *fsn_mark, __u3
 
 	spin_lock(&fsn_mark->lock);
 	oldmask = fsn_mark->mask;
-	fsn_mark->mask = oldmask & ~mask;
+	fsnotify_set_mark_mask_locked(fsn_mark, (oldmask & ~mask));
 	spin_unlock(&fsn_mark->lock);
 
 	if (!(oldmask & ~mask))
@@ -359,7 +359,7 @@ static __u32 fanotify_mark_add_to_mask(struct fsnotify_mark *fsn_mark, __u32 mas
 
 	spin_lock(&fsn_mark->lock);
 	oldmask = fsn_mark->mask;
-	fsn_mark->mask = oldmask | mask;
+	fsnotify_set_mark_mask_locked(fsn_mark, (oldmask | mask));
 	spin_unlock(&fsn_mark->lock);
 
 	return mask & ~oldmask;