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[PATCH v2 1/3] kernfs: allow passing fsnotify event types

T.J. Mercier posted 3 patches 1 month, 2 weeks ago
There is a newer version of this series
[PATCH v2 1/3] kernfs: allow passing fsnotify event types
Posted by T.J. Mercier 1 month, 2 weeks ago 
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() */
 };
 
 /*
-- 
2.53.0.273.g2a3d683680-goog
Re: [PATCH v2 1/3] kernfs: allow passing fsnotify event types
Posted by Amir Goldstein 1 month, 2 weeks ago 
On Thu, Feb 12, 2026 at 01:58:12PM -0800, T.J. Mercier wrote:
> 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>

Looks fine
Feel free to add
Acked-by: Amir Goldstein <amir73il@gmail.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() */
>  };
>  
>  /*
> -- 
> 2.53.0.273.g2a3d683680-goog
>
Re: [PATCH v2 1/3] kernfs: allow passing fsnotify event types
Posted by T.J. Mercier 1 month, 2 weeks ago 
On Mon, Feb 16, 2026 at 8:27 AM Amir Goldstein <amir73il@gmail.com> wrote:
>
> On Thu, Feb 12, 2026 at 01:58:12PM -0800, T.J. Mercier wrote:
> > 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>
>
> Looks fine
> Feel free to add
> Acked-by: Amir Goldstein <amir73il@gmail.com>

Thanks Amir.

>
> > ---
> >  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() */
> >  };
> >
> >  /*
> > --
> > 2.53.0.273.g2a3d683680-goog
> >

Patchew 2.1-devel-ea86937

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