From: Al Viro <viro@ZenIV.linux.org.uk>
To: NeilBrown <neilb@suse.de>
Cc: Trond Myklebust <trond.myklebust@primarydata.com>,
linux-nfs@vger.kernel.org
Subject: Re: [PATCH 2/8] NFS: prepare for RCU-walk support but pushing tests later in code.
Date: Wed, 5 Mar 2014 06:49:46 +0000 [thread overview]
Message-ID: <20140305064946.GY18016@ZenIV.linux.org.uk> (raw)
In-Reply-To: <20140305165933.09ca9d84@notabene.brown>
On Wed, Mar 05, 2014 at 04:59:33PM +1100, NeilBrown wrote:
> > b) having already become negative.
>
> I didn't think dentries ever became negative. When a file is deleted the old
> positive dentry is unlinked and a new negative dentry is created in it's
> place.
> Or has that changed since last I looked?
It has never been true. See what d_delete() is doing. If there was only
one reference to dentry, it *does* become negative.
> If they can become negative, then I could
> dir = ACCESS_ONCE(parent->d_inode);
> if (!dir)
> return -ECHILD;
>
> Do you think that would be safe?
Depends on what you do with it afterwards...
next prev parent reply other threads:[~2014-03-05 6:49 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-03-05 3:00 [PATCH/RFC 0/8] Extend RCU-walk support to NFS NeilBrown
2014-03-05 3:00 ` [PATCH 6/8] NFS: teach nfs_neg_need_reval to understand LOOKUP_RCU NeilBrown
2014-03-05 3:00 ` [PATCH 2/8] NFS: prepare for RCU-walk support but pushing tests later in code NeilBrown
2014-03-05 5:34 ` Al Viro
2014-03-05 5:59 ` NeilBrown
2014-03-05 6:49 ` Al Viro [this message]
2014-03-06 5:47 ` NeilBrown
2014-03-05 3:00 ` [PATCH 8/8] NFS: allow lockless access to access_cache NeilBrown
2014-03-05 15:11 ` Trond Myklebust
2014-03-06 6:03 ` NeilBrown
2014-03-05 3:00 ` [PATCH 5/8] NFS: teach nfs_do_access to understand MAY_NOT_BLOCK NeilBrown
2014-03-05 3:00 ` [PATCH 7/8] NFS: teach nfs_lookup_verify_inode to handle LOOKUP_RCU NeilBrown
2014-03-05 3:00 ` [PATCH 3/8] sunrpc/auth: allow lockless (rcu) lookup of credential cache NeilBrown
2014-03-05 3:00 ` [PATCH 1/8] NFS: nfs4_lookup_revalidate: only evaluate parent if it will be used NeilBrown
2014-03-05 3:00 ` [PATCH 4/8] sunrpc/auth: add 'rcu_walk' arg to rpc_lookup_cred NeilBrown
2014-03-05 14:43 ` Trond Myklebust
2014-03-06 5:50 ` NeilBrown
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