Messages in this thread | | | Date | Wed, 2 Dec 2020 13:37:05 -0500 | From | Tejun Heo <> | Subject | Re: [PATCH 1/2] kernfs: replace the mutex in kernfs_iop_permission with a rwlock |
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On Wed, Dec 02, 2020 at 10:58:36PM +0800, Fox Chen wrote: > diff --git a/include/linux/kernfs.h b/include/linux/kernfs.h > index 89f6a4214a70..545cdb39b34b 100644 > --- a/include/linux/kernfs.h > +++ b/include/linux/kernfs.h > @@ -156,6 +156,7 @@ struct kernfs_node { > unsigned short flags; > umode_t mode; > struct kernfs_iattrs *iattr; > + rwlock_t iattr_rwlock; > };
Also, while this might not look like much, kernfs_node is very size sensitive. There are systems with huge number of these nodes, so I don't think putting a per-node lock like this is a good idea. Either we can use a shared iattr protecting lock or play some cmpxchg games when allocating and setting ->iattr and put the lock there.
Thanks.
-- tejun
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