From mboxrd@z Thu Jan  1 00:00:00 1970
From: Eric Dumazet <eric.dumazet@gmail.com>
Subject: Re: [PATCH v3 2/4] Keep nr_dentry per super block
Date: Sun, 14 Aug 2011 19:38:42 +0200
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Cc: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
	containers@lists.linux-foundation.org,
	Pavel Emelyanov <xemul@parallels.com>,
	Al Viro <viro@zeniv.linux.org.uk>,
	Hugh Dickins <hughd@google.com>,
	Nick Piggin <npiggin@kernel.dk>,
	Andrea Arcangeli <aarcange@redhat.com>,
	Rik van Riel <riel@redhat.com>,
	Dave Hansen <dave@linux.vnet.ibm.com>,
	James Bottomley <JBottomley@Parallels.com>,
	David Chinner <david@fromorbit.com>
To: Glauber Costa <glommer@parallels.com>
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Le dimanche 14 ao=C3=BBt 2011 =C3=A0 19:13 +0400, Glauber Costa a =C3=A9=
crit :
> Now that we have per-sb shrinkers, it makes sense to have nr_dentries
> stored per sb as well. We turn them into per-cpu counters so we can
> keep acessing them without locking.
>=20
> Signed-off-by: Glauber Costa <glommer@parallels.com>

>  }
> diff --git a/fs/super.c b/fs/super.c
> index 3f56a26..e95ac4f 100644
> --- a/fs/super.c
> +++ b/fs/super.c
> @@ -119,6 +119,9 @@ static struct super_block *alloc_super(struct fil=
e_system_type *type)
>  			s =3D NULL;
>  			goto out;
>  		}
> +
> +		percpu_counter_init(&s->s_nr_dentry, 0);
> +

You should take care of possible error return at this point.

(We probably should check the percpu_counter_init() done in tcp_init(),
but they are done at boot time, with nearly no chance of failure)



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