Add three event counters to each mount object:
(1) mnt_topology_changes.
Counts the number of changes to the mount tree topology, including
addition of new mount objects, removal of mount objects and mount
objects being moved about.
(2) mnt_attr_changes.
Counts the number of changes to a mount object's attributes, such as
whether or not the device files it contains are interpretable as such.
(3) mnt_subtree_notifications.
Counts the number of events within the mount subtree at this point.
Signed-off-by: David Howells <dhowells@xxxxxxxxxx>
---
fs/mount.h | 3 +++
fs/mount_notify.c | 4 ++++
2 files changed, 7 insertions(+)
diff --git a/fs/mount.h b/fs/mount.h
index 1037781be055..9758a9fa8f69 100644
--- a/fs/mount.h
+++ b/fs/mount.h
@@ -83,6 +83,9 @@ struct mount {
u64 mnt_unique_id; /* ID unique over lifetime of kernel */
#endif
#ifdef CONFIG_MOUNT_NOTIFICATIONS
+ atomic_long_t mnt_topology_changes; /* Number of topology changes applied */
+ atomic_long_t mnt_attr_changes; /* Number of attribute changes applied */
+ atomic_long_t mnt_subtree_notifications; /* Number of notifications in subtree */
struct watch_list *mnt_watchers; /* Watches on dentries within this mount */
#endif
} __randomize_layout;
diff --git a/fs/mount_notify.c b/fs/mount_notify.c
index d8ba66ed5f77..57eebae51cb1 100644
--- a/fs/mount_notify.c
+++ b/fs/mount_notify.c
@@ -61,6 +61,7 @@ static void post_mount_notification(struct mount *changed,
cursor.dentry = READ_ONCE(mnt->mnt_mountpoint);
mnt = parent;
cursor.mnt = &mnt->mnt;
+ atomic_long_inc(&mnt->mnt_subtree_notifications);
} else {
cursor.dentry = cursor.dentry->d_parent;
}
@@ -96,6 +97,7 @@ void notify_mount(struct mount *trigger,
case NOTIFY_MOUNT_EXPIRY:
case NOTIFY_MOUNT_READONLY:
case NOTIFY_MOUNT_SETATTR:
+ atomic_long_inc(&trigger->mnt_attr_changes);
break;
case NOTIFY_MOUNT_NEW_MOUNT:
@@ -103,6 +105,8 @@ void notify_mount(struct mount *trigger,
case NOTIFY_MOUNT_MOVE_FROM:
case NOTIFY_MOUNT_MOVE_TO:
n.auxiliary_mount = aux->mnt_unique_id;
+ atomic_long_inc(&trigger->mnt_topology_changes);
+ atomic_long_inc(&aux->mnt_topology_changes);
break;
default:
