linux-kernel - Re: [patch 02/12] fuse: fix race between getattr and write

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Message-Id: <E1IdZZp-0002Xp-00@dorka.pomaz.szeredi.hu>
Date:	Fri, 05 Oct 2007 00:53:53 +0200
From:	Miklos Szeredi <miklos@...redi.hu>
To:	akpm@...ux-foundation.org
CC:	miklos@...redi.hu, linux-kernel@...r.kernel.org,
	jakub.bogusz@...ius.pl
Subject: Re: [patch 02/12] fuse: fix race between getattr and write

> > @@ -228,6 +243,7 @@ static struct dentry *fuse_lookup(struct
> >  	struct fuse_conn *fc = get_fuse_conn(dir);
> >  	struct fuse_req *req;
> >  	struct fuse_req *forget_req;
> > +	u64 attr_version;
> >  
> >  	if (entry->d_name.len > FUSE_NAME_MAX)
> >  		return ERR_PTR(-ENAMETOOLONG);
> > @@ -242,6 +258,10 @@ static struct dentry *fuse_lookup(struct
> >  		return ERR_PTR(PTR_ERR(forget_req));
> >  	}
> >  
> > +	spin_lock(&fc->lock);
> > +	attr_version = fc->attr_version;
> > +	spin_unlock(&fc->lock);
> 
> You might want to do this (oft-repeated) operation in a little helper
> function.
> 
> Because I suspect that the lock isn't needed if CONFIG_64BIT=y.

You're perfectly right, although fuse is not yet at the stage, where
I'd bother too much with scalability optimizations like that ;)

But it's a good cleanup, and I'll do an incremental patch on top of
this if that's OK.

Miklos
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