[PATCH 1/3] kernfs: allow passing fsnotify event types

T.J. Mercier
2026-02-10T00:38:29Z

The kernfs_notify function is hardcoded to only issue FS_MODIFY events
since that is the only current use case. Allow for supporting other
events by adding a notify_event field to kernfs_elem_attr. The
limitation of only one queued event per kernfs_node continues to exist
as a consequence of the design of the kernfs_notify_list. The new
notify_event field is protected by the same kernfs_notify_lock as the
existing notify_next field.

Signed-off-by: T.J. Mercier <tjmercier@google.com>
---
fs/kernfs/file.c | 8 ++++++--
include/linux/kernfs.h | 1 +
2 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/fs/kernfs/file.c b/fs/kernfs/file.c
index 9adf36e6364b..e978284ff983 100644
--- a/fs/kernfs/file.c
+++ b/fs/kernfs/file.c
@@ -914,6 +914,7 @@ static void kernfs_notify_workfn(struct work_struct *work)
struct kernfs_node *kn;
struct kernfs_super_info *info;
struct kernfs_root *root;
+ u32 notify_event;
repeat:
/* pop one off the notify_list */
spin_lock_irq(&kernfs_notify_lock);
@@ -924,6 +925,8 @@ static void kernfs_notify_workfn(struct work_struct *work)
}
kernfs_notify_list = kn->attr.notify_next;
kn->attr.notify_next = NULL;
+ notify_event = kn->attr.notify_event;
+ kn->attr.notify_event = 0;
spin_unlock_irq(&kernfs_notify_lock);

root = kernfs_root(kn);
@@ -954,7 +957,7 @@ static void kernfs_notify_workfn(struct work_struct *work)
if (parent) {
p_inode = ilookup(info->sb, kernfs_ino(parent));
if (p_inode) {
- fsnotify(FS_MODIFY | FS_EVENT_ON_CHILD,
+ fsnotify(notify_event | FS_EVENT_ON_CHILD,
inode, FSNOTIFY_EVENT_INODE,
p_inode, &name, inode, 0);
iput(p_inode);
@@ -964,7 +967,7 @@ static void kernfs_notify_workfn(struct work_struct *work)
}

if (!p_inode)
- fsnotify_inode(inode, FS_MODIFY);
+ fsnotify_inode(inode, notify_event);

iput(inode);
}
@@ -1005,6 +1008,7 @@ void kernfs_notify(struct kernfs_node *kn)
if (!kn->attr.notify_next) {
kernfs_get(kn);
kn->attr.notify_next = kernfs_notify_list;
+ kn->attr.notify_event = FS_MODIFY;
kernfs_notify_list = kn;
schedule_work(&kernfs_notify_work);
}
diff --git a/include/linux/kernfs.h b/include/linux/kernfs.h
index b5a5f32fdfd1..1762b32c1a8e 100644
--- a/include/linux/kernfs.h
+++ b/include/linux/kernfs.h
@@ -181,6 +181,7 @@ struct kernfs_elem_attr {
struct kernfs_open_node __rcu *open;
loff_t size;
struct kernfs_node *notify_next; /* for kernfs_notify() */
+ u32 notify_event; /* for kernfs_notify() */
};

/*
--
2.53.0.rc2.204.g2597b5adb4-goog