Re: [PATCH v5 09/21] nfsd: add data structures for handling CB_NOTIFY

On Mon, 2026-06-08 at 16:18 -0400, Chuck Lever wrote:
> 
> On Fri, May 22, 2026, at 3:42 PM, Jeff Layton wrote:
> > Add the data structures, allocation helpers, and callback operations
> > needed for directory delegation CB_NOTIFY support:
> 
> > diff --git a/fs/nfsd/state.h b/fs/nfsd/state.h
> > index 9c6e2e7abc82..505fabf8f1bf 100644
> > --- a/fs/nfsd/state.h
> > +++ b/fs/nfsd/state.h
> > @@ -197,6 +197,44 @@ struct nfs4_cb_fattr {
> >  #define NOTIFY4_EVENT_QUEUE_SIZE	3
> >  #define NOTIFY4_PAGE_ARRAY_SIZE		1
> > 
> > +struct nfsd_notify_event {
> > +	refcount_t	ne_ref;		// refcount
> > +	u32		ne_mask;	// FS_* mask from fsnotify callback
> > +	struct dentry	*ne_dentry;	// dentry reference to target
> > +	u32		ne_namelen;	// length of ne_name
> > +	char		ne_name[];	// name of dentry being changed
> 
> Nit: checkpatch doesn't like the C++ comment style.
> 
> 
> > +};
> > +
> > +static inline struct nfsd_notify_event *nfsd_notify_event_get(struct 
> > nfsd_notify_event *ne)
> > +{
> > +	refcount_inc(&ne->ne_ref);
> > +	return ne;
> > +}
> > +
> > +static inline void nfsd_notify_event_put(struct nfsd_notify_event *ne)
> > +{
> > +	if (refcount_dec_and_test(&ne->ne_ref)) {
> > +		dput(ne->ne_dentry);
> > +		kfree(ne);
> > +	}
> > +}
> > +
> > +/*
> > + * Represents a directory delegation. The callback is for handling 
> > CB_NOTIFYs.
> > + * As notifications from fsnotify come in, allocate a new event, take 
> > the ncn_lock,
> > + * and add it to the ncn_evt queue. The CB_NOTIFY prepare handler will 
> > take the
> > + * lock, clean out the list and process it.
> > + */
> > +struct nfsd4_cb_notify {
> > +	spinlock_t			ncn_lock;	// protects the evt queue and count
> > +	int				ncn_evt_cnt;	// count of events in ncn_evt
> > +	int				ncn_nf_cnt;	// count of valid entries in ncn_nf
> > +	struct nfsd_notify_event	*ncn_evt[NOTIFY4_EVENT_QUEUE_SIZE]; // list 
> > of events
> > +	struct page			*ncn_pages[NOTIFY4_PAGE_ARRAY_SIZE]; // for encoding
> > +	struct notify4			*ncn_nf;	// array of notify4's to be sent
> > +	struct nfsd4_callback		ncn_cb;		// notify4 callback
> > +};
> 
> Ditto.
> 


I'll note that the code is littered with this comment style anyway,
including a bunch of the new // SPDX- header comments. Personally, I
find this more readable for documenting struct fields.

AFAICT, the checkpatch rule was manufactured out of thin air.
Documentation/dev-tools/checkpatch.rst says:

  **C99_COMMENTS**
    C99 style single line comments (//) should not be used.
    Prefer the block comment style instead.

    See:
https://www.kernel.org/doc/html/latest/process/coding-style.html#commenting

...but that coding-style document says nothing about C99 comments. I
move that we ignore checkpatch here.
-- 
Jeff Layton <[email protected]>