linux-kernel - Re: [PATCH v3 22/38] vfs: add fsnotify_modify_mark

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Message-ID: <mr6lfsrdp77g7ndnhignxby6fniku2fb3u5yykvwng67sneo7o@d6dozubh4t4c>
Date: Thu, 25 Sep 2025 17:50:07 +0200
From: Jan Kara <jack@...e.cz>
To: Jeff Layton <jlayton@...nel.org>
Cc: Alexander Viro <viro@...iv.linux.org.uk>, 
	Christian Brauner <brauner@...nel.org>, Jan Kara <jack@...e.cz>, Chuck Lever <chuck.lever@...cle.com>, 
	Alexander Aring <alex.aring@...il.com>, Trond Myklebust <trondmy@...nel.org>, 
	Anna Schumaker <anna@...nel.org>, Steve French <sfrench@...ba.org>, 
	Ronnie Sahlberg <ronniesahlberg@...il.com>, Shyam Prasad N <sprasad@...rosoft.com>, 
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Subject: Re: [PATCH v3 22/38] vfs: add fsnotify_modify_mark_mask()

On Wed 24-09-25 14:06:08, Jeff Layton wrote:
> nfsd needs to be able to modify the mask on an existing mark when new
> directory delegations are set or unset. Add an exported function that
> allows the caller to set and clear bits in the mark->mask, and does
> the recalculation if something changed.
> 
> Suggested-by: Jan Kara <jack@...e.cz>
> Signed-off-by: Jeff Layton <jlayton@...nel.org>

Looks good. Feel free to add:

Acked-by: Jan Kara <jack@...e.cz>

								Honza

> ---
>  fs/notify/mark.c                 | 29 +++++++++++++++++++++++++++++
>  include/linux/fsnotify_backend.h |  1 +
>  2 files changed, 30 insertions(+)
> 
> diff --git a/fs/notify/mark.c b/fs/notify/mark.c
> index 798340db69d761dd05c1b361c251818dee89b9cf..5ed42b24df7f6aa3812a7069b4c37f0c6b3414fa 100644
> --- a/fs/notify/mark.c
> +++ b/fs/notify/mark.c
> @@ -309,6 +309,35 @@ void fsnotify_recalc_mask(struct fsnotify_mark_connector *conn)
>  		fsnotify_conn_set_children_dentry_flags(conn);
>  }
>  
> +/**
> + * fsnotify_modify_mark_mask - set and/or clear flags in a mark's mask
> + * @mark: mark to be modified
> + * @set: bits to be set in mask
> + * @clear: bits to be cleared in mask
> + *
> + * Modify a fsnotify_mark mask as directed, and update its associated conn.
> + * The caller is expected to hold a reference to the mark.
> + */
> +void fsnotify_modify_mark_mask(struct fsnotify_mark *mark, u32 set, u32 clear)
> +{
> +	bool recalc = false;
> +	u32 mask;
> +
> +	WARN_ON_ONCE(clear & set);
> +
> +	spin_lock(&mark->lock);
> +	mask = mark->mask;
> +	mark->mask |= set;
> +	mark->mask &= ~clear;
> +	if (mark->mask != mask)
> +		recalc = true;
> +	spin_unlock(&mark->lock);
> +
> +	if (recalc)
> +		fsnotify_recalc_mask(mark->connector);
> +}
> +EXPORT_SYMBOL_GPL(fsnotify_modify_mark_mask);
> +
>  /* Free all connectors queued for freeing once SRCU period ends */
>  static void fsnotify_connector_destroy_workfn(struct work_struct *work)
>  {
> diff --git a/include/linux/fsnotify_backend.h b/include/linux/fsnotify_backend.h
> index d4034ddaf3926bf98d8801997e50ba7ddf776292..8d50e6aad3c62c67a9bf73a8d9aab78565668c5f 100644
> --- a/include/linux/fsnotify_backend.h
> +++ b/include/linux/fsnotify_backend.h
> @@ -912,6 +912,7 @@ extern void fsnotify_get_mark(struct fsnotify_mark *mark);
>  extern void fsnotify_put_mark(struct fsnotify_mark *mark);
>  extern void fsnotify_finish_user_wait(struct fsnotify_iter_info *iter_info);
>  extern bool fsnotify_prepare_user_wait(struct fsnotify_iter_info *iter_info);
> +extern void fsnotify_modify_mark_mask(struct fsnotify_mark *mark, u32 set, u32 clear);
>  
>  static inline void fsnotify_init_event(struct fsnotify_event *event)
>  {
> 
> -- 
> 2.51.0
> 
-- 
Jan Kara <jack@...e.com>
SUSE Labs, CR