From bb20c18db6fbb5e6ba499c76473a487d35073467 Mon Sep 17 00:00:00 2001 From: Nick Piggin Date: Fri, 14 Jan 2011 02:35:53 +0000 Subject: [PATCH] fs: force_reval_path drop rcu-walk before d_invalidate d_revalidate can return in rcu-walk mode even when it returns 0. We can't just call any old dcache function on rcu-walk dentry (the dentry is unstable, so even through d_lock can safely be taken, the result may no longer be what we expect -- careful re-checks would be required). So just drop rcu in this case. (I missed this conversion when switching to the rcu-walk convention that Linus suggested) Signed-off-by: Nick Piggin --- fs/namei.c | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/fs/namei.c b/fs/namei.c index 19433cdba011..0f02359ce685 100644 --- a/fs/namei.c +++ b/fs/namei.c @@ -583,6 +583,13 @@ void release_open_intent(struct nameidata *nd) fput(nd->intent.open.file); } +/* + * Call d_revalidate and handle filesystems that request rcu-walk + * to be dropped. This may be called and return in rcu-walk mode, + * regardless of success or error. If -ECHILD is returned, the caller + * must return -ECHILD back up the path walk stack so path walk may + * be restarted in ref-walk mode. + */ static int d_revalidate(struct dentry *dentry, struct nameidata *nd) { int status; @@ -673,6 +680,9 @@ force_reval_path(struct path *path, struct nameidata *nd) return 0; if (!status) { + /* Don't d_invalidate in rcu-walk mode */ + if (nameidata_drop_rcu(nd)) + return -ECHILD; d_invalidate(dentry); status = -ESTALE; } -- 2.20.1