Re: [PATCH v1 03/12] fsnotify: don't hold a spin_lock across fsnotify_recalc_mask() calls.

[NeilBrown]

On Tue, 11 Aug 2026, Miklos Szeredi wrote:
> On Mon, 3 Aug 2026 at 03:39, NeilBrown <neilb@xxxxxxxxxxx> wrote:
> 
> > @@ -116,11 +117,15 @@ static int dnotify_handle_event(struct fsnotify_mark *inode_mark, u32 mask,
> >                 else {
> >                         *prev = dn->dn_next;
> >                         kmem_cache_free(dnotify_struct_cache, dn);
> > -                       dnotify_recalc_inode_mask(inode_mark);
> > +                       need_recalc = true;
> >                 }
> >         }
> >
> > +       if (need_recalc)
> > +               need_recalc = dnotify_recalc_inode_mask(inode_mark);
> >         spin_unlock(&inode_mark->lock);
> > +       if (need_recalc)
> > +               fsnotify_recalc_mask(inode_mark->connector);
> 
> Is the fsnotify_group_lock() held in this case?   I don't see it.

It isn't held.  Doesn't it need to be...
It seems to protect marks, so maybe it does.

srcu seems to be used to protect this section, so maybe we can rely on
that.
Maybe:

diff --git a/fs/notify/dnotify/dnotify.c b/fs/notify/dnotify/dnotify.c
index 7553fe0d7850..ba746284bded 100644
--- a/fs/notify/dnotify/dnotify.c
+++ b/fs/notify/dnotify/dnotify.c
@@ -17,6 +17,7 @@
 #include <linux/spinlock.h>
 #include <linux/slab.h>
 #include <linux/fsnotify_backend.h>
+#include "../fsnotify.h"
 
 static int dir_notify_enable __read_mostly = 1;
 #ifdef CONFIG_SYSCTL
@@ -94,6 +95,7 @@ static int dnotify_handle_event(struct fsnotify_mark *inode_mark, u32 mask,
 	struct dnotify_struct *dn;
 	struct dnotify_struct **prev;
 	struct fown_struct *fown;
+	struct fsnotify_mark_connector *conn;
 	bool need_recalc = false;
 	__u32 test_mask = mask & ~FS_EVENT_ON_CHILD;
 
@@ -123,9 +125,10 @@ static int dnotify_handle_event(struct fsnotify_mark *inode_mark, u32 mask,
 
 	if (need_recalc)
 		need_recalc = dnotify_recalc_inode_mask(inode_mark);
+	conn = srcu_dereference(inode_mark->connector, &fsnotify_mark_srcu);
 	spin_unlock(&inode_mark->lock);
 	if (need_recalc)
-		fsnotify_recalc_mask(inode_mark->connector);
+		fsnotify_recalc_mask(conn);
 
 	return 0;
 }

Does that make sense?

Thanks,
NeilBrown