linux/net/sunrpc/backchannel_rqst.c

// SPDX-License-Identifier: GPL-2.0-only
/******************************************************************************

(c) 2007 Network Appliance, Inc.  All Rights Reserved.
(c) 2009 NetApp.  All Rights Reserved.


******************************************************************************/

#include <linux/tcp.h>
#include <linux/slab.h>
#include <linux/sunrpc/xprt.h>
#include <linux/export.h>
#include <linux/sunrpc/bc_xprt.h>

#if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
#define RPCDBG_FACILITY …
#endif

#define BC_MAX_SLOTS …

unsigned int xprt_bc_max_slots(struct rpc_xprt *xprt)
{ … }

/*
 * Helper routines that track the number of preallocation elements
 * on the transport.
 */
static inline int xprt_need_to_requeue(struct rpc_xprt *xprt)
{ … }

/*
 * Free the preallocated rpc_rqst structure and the memory
 * buffers hanging off of it.
 */
static void xprt_free_allocation(struct rpc_rqst *req)
{ … }

static void xprt_bc_reinit_xdr_buf(struct xdr_buf *buf)
{ … }

static int xprt_alloc_xdr_buf(struct xdr_buf *buf, gfp_t gfp_flags)
{ … }

static struct rpc_rqst *xprt_alloc_bc_req(struct rpc_xprt *xprt)
{ … }

/*
 * Preallocate up to min_reqs structures and related buffers for use
 * by the backchannel.  This function can be called multiple times
 * when creating new sessions that use the same rpc_xprt.  The
 * preallocated buffers are added to the pool of resources used by
 * the rpc_xprt.  Any one of these resources may be used by an
 * incoming callback request.  It's up to the higher levels in the
 * stack to enforce that the maximum number of session slots is not
 * being exceeded.
 *
 * Some callback arguments can be large.  For example, a pNFS server
 * using multiple deviceids.  The list can be unbound, but the client
 * has the ability to tell the server the maximum size of the callback
 * requests.  Each deviceID is 16 bytes, so allocate one page
 * for the arguments to have enough room to receive a number of these
 * deviceIDs.  The NFS client indicates to the pNFS server that its
 * callback requests can be up to 4096 bytes in size.
 */
int xprt_setup_backchannel(struct rpc_xprt *xprt, unsigned int min_reqs)
{ … }
EXPORT_SYMBOL_GPL(…);

int xprt_setup_bc(struct rpc_xprt *xprt, unsigned int min_reqs)
{ … }

/**
 * xprt_destroy_backchannel - Destroys the backchannel preallocated structures.
 * @xprt:	the transport holding the preallocated strucures
 * @max_reqs:	the maximum number of preallocated structures to destroy
 *
 * Since these structures may have been allocated by multiple calls
 * to xprt_setup_backchannel, we only destroy up to the maximum number
 * of reqs specified by the caller.
 */
void xprt_destroy_backchannel(struct rpc_xprt *xprt, unsigned int max_reqs)
{ … }
EXPORT_SYMBOL_GPL(…);

void xprt_destroy_bc(struct rpc_xprt *xprt, unsigned int max_reqs)
{ … }

static struct rpc_rqst *xprt_get_bc_request(struct rpc_xprt *xprt, __be32 xid,
		struct rpc_rqst *new)
{ … }

/*
 * Return the preallocated rpc_rqst structure and XDR buffers
 * associated with this rpc_task.
 */
void xprt_free_bc_request(struct rpc_rqst *req)
{ … }

void xprt_free_bc_rqst(struct rpc_rqst *req)
{ … }

/*
 * One or more rpc_rqst structure have been preallocated during the
 * backchannel setup.  Buffer space for the send and private XDR buffers
 * has been preallocated as well.  Use xprt_alloc_bc_request to allocate
 * to this request.  Use xprt_free_bc_request to return it.
 *
 * We know that we're called in soft interrupt context, grab the spin_lock
 * since there is no need to grab the bottom half spin_lock.
 *
 * Return an available rpc_rqst, otherwise NULL if non are available.
 */
struct rpc_rqst *xprt_lookup_bc_request(struct rpc_xprt *xprt, __be32 xid)
{ … }

/*
 * Add callback request to callback list.  Wake a thread
 * on the first pool (usually the only pool) to handle it.
 */
void xprt_complete_bc_request(struct rpc_rqst *req, uint32_t copied)
{ … }