On Mon, 2008-11-10 at 16:18 -0500, J. Bruce Fields wrote:
> On Mon, Nov 10, 2008 at 03:37:57PM -0500, bfields wrote:
> > On Mon, Nov 10, 2008 at 03:35:22PM -0500, Trond Myklebust wrote:
> > > BTW: This is racy. You have to set first_open _after_ you take the
> > > inode->i_mutex.
> >
> > Whoops! Good catch, thanks--fixed.
>
> (Updated version follows.)
Err... This doesn't look right. This would be a mix of 4/9 and 5/9...
> --b.
>
> commit 7f5c491a32857dc8ba587cc365a2d70024f7b33e
> Author: J. Bruce Fields <bfields@xxxxxxxxxxxxxx>
> Date: Fri Nov 7 18:53:24 2008 -0500
>
> rpc: call release_pipe only on last close
>
> I can't see any reason we need to call this until either the kernel or
> the last gssd closes the pipe.
>
> Also, this allows to guarantee that open_pipe and release_pipe are
> called strictly in pairs; open_pipe on gssd's first open, release_pipe
> on gssd's last close (or on the close of the kernel side of the pipe, if
> that comes first).
>
> That will make it very easy for the gss code to keep track of which
> pipes gssd is using.
>
> Signed-off-by: J. Bruce Fields <bfields@xxxxxxxxxxxxxx>
>
> diff --git a/net/sunrpc/rpc_pipe.c b/net/sunrpc/rpc_pipe.c
> index 4171ab7..f734103 100644
> --- a/net/sunrpc/rpc_pipe.c
> +++ b/net/sunrpc/rpc_pipe.c
> @@ -126,13 +126,14 @@ rpc_close_pipes(struct inode *inode)
> {
> struct rpc_inode *rpci = RPC_I(inode);
> struct rpc_pipe_ops *ops;
> + int still_open;
>
> mutex_lock(&inode->i_mutex);
> ops = rpci->ops;
> if (ops != NULL) {
> LIST_HEAD(free_list);
> -
> spin_lock(&inode->i_lock);
> + still_open = rpci->nreaders != 0 || rpci->nwriters != 0;
> rpci->nreaders = 0;
> list_splice_init(&rpci->in_upcall, &free_list);
> list_splice_init(&rpci->pipe, &free_list);
> @@ -141,7 +142,7 @@ rpc_close_pipes(struct inode *inode)
> spin_unlock(&inode->i_lock);
> rpc_purge_list(rpci, &free_list, ops->destroy_msg, -EPIPE);
> rpci->nwriters = 0;
> - if (ops->release_pipe)
> + if (still_open && ops->release_pipe)
> ops->release_pipe(inode);
> cancel_delayed_work_sync(&rpci->queue_timeout);
> }
> @@ -169,12 +170,13 @@ static int
> rpc_pipe_open(struct inode *inode, struct file *filp)
> {
> struct rpc_inode *rpci = RPC_I(inode);
> - int first_open = rpci->nreaders == 0 && rpci->nwriters == 0;
> + int first_open;
> int res = -ENXIO;
>
> mutex_lock(&inode->i_mutex);
> if (rpci->ops == NULL)
> goto out;
> + first_open = rpci->nreaders == 0 && rpci->nwriters == 0;
> if (first_open && rpci->ops->open_pipe) {
> res = rpci->ops->open_pipe(inode);
> if (res)
> @@ -195,6 +197,7 @@ rpc_pipe_release(struct inode *inode, struct file *filp)
> {
> struct rpc_inode *rpci = RPC_I(inode);
> struct rpc_pipe_msg *msg;
> + int last_close;
>
> mutex_lock(&inode->i_mutex);
> if (rpci->ops == NULL)
> @@ -221,7 +224,8 @@ rpc_pipe_release(struct inode *inode, struct file *filp)
> rpci->ops->destroy_msg, -EAGAIN);
> }
> }
> - if (rpci->ops->release_pipe)
> + last_close = rpci->nwriters == 0 && rpci->nreaders == 0;
> + if (last_close && rpci->ops->release_pipe)
> rpci->ops->release_pipe(inode);
> out:
> mutex_unlock(&inode->i_mutex);
--
Trond Myklebust
Linux NFS client maintainer
NetApp
Trond.Myklebust@xxxxxxxxxx
www.netapp.com
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