rpc: add an rpc_pipe_open method (c3810608) · Commits · 戴 / test

We want to transition to a new gssd upcall which is text-based and more easily extensible. To simplify upgrades, as well as testing and debugging, it will help if we can upgrade gssd (to a version which understands the new upcall) without having to choose at boot (or module-load) time whether we want the new or the old upcall. We will do this by providing two different pipes: one named, as currently, after the mechanism (normally "krb5"), and supporting the old upcall. One named "gssd" and supporting the new upcall version. We allow gssd to indicate which version it supports by its choice of which pipe to open. As we have no interest in supporting *simultaneous* use of both versions, we'll forbid opening both pipes at the same time. So, add a new pipe_open callback to the rpc_pipefs api, which the gss code can use to track which pipes have been open, and to refuse opens of incompatible pipes. We only need this to be called on the first open of a given pipe. Signed-off-by:

J. Bruce Fields <bfields@citi.umich.edu> Signed-off-by:

Trond Myklebust <Trond.Myklebust@netapp.com>

include/linux/sunrpc/rpc_pipe_fs.h

+1 −0

Original line number	Diff line number	Diff line
		@@ -15,6 +15,7 @@ struct rpc_pipe_ops {
		ssize_t (upcall)(struct file , struct rpc_pipe_msg , char __user , size_t);
		ssize_t (downcall)(struct file , const char __user *, size_t);
		void (release_pipe)(struct inode );
		int (open_pipe)(struct inode );
		void (destroy_msg)(struct rpc_pipe_msg );
		};

net/sunrpc/rpc_pipe.c

+15 −7

Original line number	Diff line number	Diff line
		@@ -169,16 +169,24 @@ static int
		rpc_pipe_open(struct inode inode, struct file filp)
		{
		struct rpc_inode *rpci = RPC_I(inode);
		int first_open;
		int res = -ENXIO;

		mutex_lock(&inode->i_mutex);
		if (rpci->ops != NULL) {
		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)
		goto out;
		}
		if (filp->f_mode & FMODE_READ)
		rpci->nreaders++;
		if (filp->f_mode & FMODE_WRITE)
		rpci->nwriters++;
		res = 0;
		}
		out:
		mutex_unlock(&inode->i_mutex);
		return res;
		}
		@@ -748,7 +756,7 @@ rpc_rmdir(struct dentry *dentry)
		* @name: name of pipe
		* @private: private data to associate with the pipe, for the caller's use
		* @ops: operations defining the behavior of the pipe: upcall, downcall,
		* release_pipe, and destroy_msg.
		* release_pipe, open_pipe, and destroy_msg.
		* @flags: rpc_inode flags
		*
		* Data is made available for userspace to read by calls to

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