[linux-block.git] / net / sunrpc / backchannel_rqst.c

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

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

NetApp provides this source code under the GPL v2 License.
The GPL v2 license is available at
http://opensource.org/licenses/gpl-license.php.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

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

#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	RPCDBG_TRANS
#endif

/*
 * Helper routines that track the number of preallocation elements
 * on the transport.
 */
static inline int xprt_need_to_requeue(struct rpc_xprt *xprt)
{
	return xprt->bc_alloc_count > 0;
}

static inline void xprt_inc_alloc_count(struct rpc_xprt *xprt, unsigned int n)
{
	xprt->bc_alloc_count += n;
}

static inline int xprt_dec_alloc_count(struct rpc_xprt *xprt, unsigned int n)
{
	return xprt->bc_alloc_count -= n;
}

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

	dprintk("RPC:        free allocations for req= %p\n", req);
	WARN_ON_ONCE(test_bit(RPC_BC_PA_IN_USE, &req->rq_bc_pa_state));
	xbufp = &req->rq_rcv_buf;
	free_page((unsigned long)xbufp->head[0].iov_base);
	xbufp = &req->rq_snd_buf;
	free_page((unsigned long)xbufp->head[0].iov_base);
	kfree(req);
}

static int xprt_alloc_xdr_buf(struct xdr_buf *buf, gfp_t gfp_flags)
{
	struct page *page;
	/* Preallocate one XDR receive buffer */
	page = alloc_page(gfp_flags);
	if (page == NULL)
		return -ENOMEM;
	buf->head[0].iov_base = page_address(page);
	buf->head[0].iov_len = PAGE_SIZE;
	buf->tail[0].iov_base = NULL;
	buf->tail[0].iov_len = 0;
	buf->page_len = 0;
	buf->len = 0;
	buf->buflen = PAGE_SIZE;
	return 0;
}

static
struct rpc_rqst *xprt_alloc_bc_req(struct rpc_xprt *xprt, gfp_t gfp_flags)
{
	struct rpc_rqst *req;

	/* Pre-allocate one backchannel rpc_rqst */
	req = kzalloc(sizeof(*req), gfp_flags);
	if (req == NULL)
		return NULL;

	req->rq_xprt = xprt;
	INIT_LIST_HEAD(&req->rq_list);
	INIT_LIST_HEAD(&req->rq_bc_list);

	/* Preallocate one XDR receive buffer */
	if (xprt_alloc_xdr_buf(&req->rq_rcv_buf, gfp_flags) < 0) {
		printk(KERN_ERR "Failed to create bc receive xbuf\n");
		goto out_free;
	}
	req->rq_rcv_buf.len = PAGE_SIZE;

	/* Preallocate one XDR send buffer */
	if (xprt_alloc_xdr_buf(&req->rq_snd_buf, gfp_flags) < 0) {
		printk(KERN_ERR "Failed to create bc snd xbuf\n");
		goto out_free;
	}
	return req;
out_free:
	xprt_free_allocation(req);
	return NULL;
}

/*
 * 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.  Anyone of these resources may be used 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)
{
	struct rpc_rqst *req;
	struct list_head tmp_list;
	int i;

	dprintk("RPC:       setup backchannel transport\n");

	/*
	 * We use a temporary list to keep track of the preallocated
	 * buffers.  Once we're done building the list we splice it
	 * into the backchannel preallocation list off of the rpc_xprt
	 * struct.  This helps minimize the amount of time the list
	 * lock is held on the rpc_xprt struct.  It also makes cleanup
	 * easier in case of memory allocation errors.
	 */
	INIT_LIST_HEAD(&tmp_list);
	for (i = 0; i < min_reqs; i++) {
		/* Pre-allocate one backchannel rpc_rqst */
		req = xprt_alloc_bc_req(xprt, GFP_KERNEL);
		if (req == NULL) {
			printk(KERN_ERR "Failed to create bc rpc_rqst\n");
			goto out_free;
		}

		/* Add the allocated buffer to the tmp list */
		dprintk("RPC:       adding req= %p\n", req);
		list_add(&req->rq_bc_pa_list, &tmp_list);
	}

	/*
	 * Add the temporary list to the backchannel preallocation list
	 */
	spin_lock_bh(&xprt->bc_pa_lock);
	list_splice(&tmp_list, &xprt->bc_pa_list);
	xprt_inc_alloc_count(xprt, min_reqs);
	spin_unlock_bh(&xprt->bc_pa_lock);

	dprintk("RPC:       setup backchannel transport done\n");
	return 0;

out_free:
	/*
	 * Memory allocation failed, free the temporary list
	 */
	while (!list_empty(&tmp_list)) {
		req = list_first_entry(&tmp_list,
				struct rpc_rqst,
				rq_bc_pa_list);
		list_del(&req->rq_bc_pa_list);
		xprt_free_allocation(req);
	}

	dprintk("RPC:       setup backchannel transport failed\n");
	return -ENOMEM;
}
EXPORT_SYMBOL_GPL(xprt_setup_backchannel);

/**
 * 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)
{
	struct rpc_rqst *req = NULL, *tmp = NULL;

	dprintk("RPC:        destroy backchannel transport\n");

	if (max_reqs == 0)
		goto out;

	spin_lock_bh(&xprt->bc_pa_lock);
	xprt_dec_alloc_count(xprt, max_reqs);
	list_for_each_entry_safe(req, tmp, &xprt->bc_pa_list, rq_bc_pa_list) {
		dprintk("RPC:        req=%p\n", req);
		list_del(&req->rq_bc_pa_list);
		xprt_free_allocation(req);
		if (--max_reqs == 0)
			break;
	}
	spin_unlock_bh(&xprt->bc_pa_lock);

out:
	dprintk("RPC:        backchannel list empty= %s\n",
		list_empty(&xprt->bc_pa_list) ? "true" : "false");
}
EXPORT_SYMBOL_GPL(xprt_destroy_backchannel);

static struct rpc_rqst *xprt_alloc_bc_request(struct rpc_xprt *xprt, __be32 xid)
{
	struct rpc_rqst *req = NULL;

	dprintk("RPC:       allocate a backchannel request\n");
	if (list_empty(&xprt->bc_pa_list))
		goto not_found;

	req = list_first_entry(&xprt->bc_pa_list, struct rpc_rqst,
				rq_bc_pa_list);
	req->rq_reply_bytes_recvd = 0;
	req->rq_bytes_sent = 0;
	memcpy(&req->rq_private_buf, &req->rq_rcv_buf,
			sizeof(req->rq_private_buf));
	req->rq_xid = xid;
	req->rq_connect_cookie = xprt->connect_cookie;
not_found:
	dprintk("RPC:       backchannel req=%p\n", req);
	return req;
}

/*
 * Return the preallocated rpc_rqst structure and XDR buffers
 * associated with this rpc_task.
 */
void xprt_free_bc_request(struct rpc_rqst *req)
{
	struct rpc_xprt *xprt = req->rq_xprt;

	dprintk("RPC:       free backchannel req=%p\n", req);

	req->rq_connect_cookie = xprt->connect_cookie - 1;
	smp_mb__before_atomic();
	WARN_ON_ONCE(!test_bit(RPC_BC_PA_IN_USE, &req->rq_bc_pa_state));
	clear_bit(RPC_BC_PA_IN_USE, &req->rq_bc_pa_state);
	smp_mb__after_atomic();

	if (!xprt_need_to_requeue(xprt)) {
		/*
		 * The last remaining session was destroyed while this
		 * entry was in use.  Free the entry and don't attempt
		 * to add back to the list because there is no need to
		 * have anymore preallocated entries.
		 */
		dprintk("RPC:       Last session removed req=%p\n", req);
		xprt_free_allocation(req);
		return;
	}

	/*
	 * Return it to the list of preallocations so that it
	 * may be reused by a new callback request.
	 */
	spin_lock_bh(&xprt->bc_pa_lock);
	list_add_tail(&req->rq_bc_pa_list, &xprt->bc_pa_list);
	spin_unlock_bh(&xprt->bc_pa_lock);
}

/*
 * 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)
{
	struct rpc_rqst *req;

	spin_lock(&xprt->bc_pa_lock);
	list_for_each_entry(req, &xprt->bc_pa_list, rq_bc_pa_list) {
		if (req->rq_connect_cookie != xprt->connect_cookie)
			continue;
		if (req->rq_xid == xid)
			goto found;
	}
	req = xprt_alloc_bc_request(xprt, xid);
found:
	spin_unlock(&xprt->bc_pa_lock);
	return req;
}

/*
 * Add callback request to callback list.  The callback
 * service sleeps on the sv_cb_waitq waiting for new
 * requests.  Wake it up after adding enqueing the
 * request.
 */
void xprt_complete_bc_request(struct rpc_rqst *req, uint32_t copied)
{
	struct rpc_xprt *xprt = req->rq_xprt;
	struct svc_serv *bc_serv = xprt->bc_serv;

	spin_lock(&xprt->bc_pa_lock);
	list_del(&req->rq_bc_pa_list);
	spin_unlock(&xprt->bc_pa_lock);

	req->rq_private_buf.len = copied;
	set_bit(RPC_BC_PA_IN_USE, &req->rq_bc_pa_state);

	dprintk("RPC:       add callback request to list\n");
	spin_lock(&bc_serv->sv_cb_lock);
	list_add(&req->rq_bc_list, &bc_serv->sv_cb_list);
	wake_up(&bc_serv->sv_cb_waitq);
	spin_unlock(&bc_serv->sv_cb_lock);
}
Commit	Line	Data
fb7a0b9a RL	1	/******************************************************************************
	2
	3	(c) 2007 Network Appliance, Inc. All Rights Reserved.
	4	(c) 2009 NetApp. All Rights Reserved.
	5
	6	NetApp provides this source code under the GPL v2 License.
	7	The GPL v2 license is available at
	8	http://opensource.org/licenses/gpl-license.php.
	9
	10	THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
	11	"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
	12	LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
	13	A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
	14	CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
	15	EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
	16	PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
	17	PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
	18	LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
	19	NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
	20	SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
	21
	22	******************************************************************************/
	23
	24	#include <linux/tcp.h>
5a0e3ad6	25	#include <linux/slab.h>
fb7a0b9a	26	#include <linux/sunrpc/xprt.h>
bc3b2d7f	27	#include <linux/export.h>
09acfea5	28	#include <linux/sunrpc/bc_xprt.h>
fb7a0b9a	29
f895b252	30	#if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
fb7a0b9a RL	31	#define RPCDBG_FACILITY RPCDBG_TRANS
	32	#endif
	33
fb7a0b9a RL	34	/*
	35	* Helper routines that track the number of preallocation elements
	36	* on the transport.
	37	*/
	38	static inline int xprt_need_to_requeue(struct rpc_xprt *xprt)
	39	{
	40	return xprt->bc_alloc_count > 0;
	41	}
	42
	43	static inline void xprt_inc_alloc_count(struct rpc_xprt *xprt, unsigned int n)
	44	{
	45	xprt->bc_alloc_count += n;
	46	}
	47
	48	static inline int xprt_dec_alloc_count(struct rpc_xprt *xprt, unsigned int n)
	49	{
	50	return xprt->bc_alloc_count -= n;
	51	}
	52
	53	/*
	54	* Free the preallocated rpc_rqst structure and the memory
	55	* buffers hanging off of it.
	56	*/
	57	static void xprt_free_allocation(struct rpc_rqst *req)
	58	{
	59	struct xdr_buf *xbufp;
	60
	61	dprintk("RPC: free allocations for req= %p\n", req);
f30dfbba	62	WARN_ON_ONCE(test_bit(RPC_BC_PA_IN_USE, &req->rq_bc_pa_state));
88de6af2	63	xbufp = &req->rq_rcv_buf;
fb7a0b9a RL	64	free_page((unsigned long)xbufp->head[0].iov_base);
	65	xbufp = &req->rq_snd_buf;
	66	free_page((unsigned long)xbufp->head[0].iov_base);
fb7a0b9a RL	67	kfree(req);
	68	}
	69
1dddda86 TM	70	static int xprt_alloc_xdr_buf(struct xdr_buf *buf, gfp_t gfp_flags)
	71	{
	72	struct page *page;
	73	/* Preallocate one XDR receive buffer */
	74	page = alloc_page(gfp_flags);
	75	if (page == NULL)
	76	return -ENOMEM;
	77	buf->head[0].iov_base = page_address(page);
	78	buf->head[0].iov_len = PAGE_SIZE;
	79	buf->tail[0].iov_base = NULL;
	80	buf->tail[0].iov_len = 0;
	81	buf->page_len = 0;
	82	buf->len = 0;
	83	buf->buflen = PAGE_SIZE;
	84	return 0;
	85	}
	86
	87	static
	88	struct rpc_rqst xprt_alloc_bc_req(struct rpc_xprt xprt, gfp_t gfp_flags)
	89	{
	90	struct rpc_rqst *req;
	91
	92	/* Pre-allocate one backchannel rpc_rqst */
	93	req = kzalloc(sizeof(*req), gfp_flags);
	94	if (req == NULL)
	95	return NULL;
	96
	97	req->rq_xprt = xprt;
	98	INIT_LIST_HEAD(&req->rq_list);
	99	INIT_LIST_HEAD(&req->rq_bc_list);
	100
	101	/* Preallocate one XDR receive buffer */
	102	if (xprt_alloc_xdr_buf(&req->rq_rcv_buf, gfp_flags) < 0) {
	103	printk(KERN_ERR "Failed to create bc receive xbuf\n");
	104	goto out_free;
	105	}
	106	req->rq_rcv_buf.len = PAGE_SIZE;
	107
	108	/* Preallocate one XDR send buffer */
	109	if (xprt_alloc_xdr_buf(&req->rq_snd_buf, gfp_flags) < 0) {
	110	printk(KERN_ERR "Failed to create bc snd xbuf\n");
	111	goto out_free;
	112	}
	113	return req;
	114	out_free:
	115	xprt_free_allocation(req);
	116	return NULL;
	117	}
	118
fb7a0b9a RL	119	/*
	120	* Preallocate up to min_reqs structures and related buffers for use
	121	* by the backchannel. This function can be called multiple times
	122	* when creating new sessions that use the same rpc_xprt. The
	123	* preallocated buffers are added to the pool of resources used by
	124	* the rpc_xprt. Anyone of these resources may be used used by an
	125	* incoming callback request. It's up to the higher levels in the
	126	* stack to enforce that the maximum number of session slots is not
	127	* being exceeded.
	128	*
	129	* Some callback arguments can be large. For example, a pNFS server
	130	* using multiple deviceids. The list can be unbound, but the client
	131	* has the ability to tell the server the maximum size of the callback
	132	* requests. Each deviceID is 16 bytes, so allocate one page
	133	* for the arguments to have enough room to receive a number of these
	134	* deviceIDs. The NFS client indicates to the pNFS server that its
	135	* callback requests can be up to 4096 bytes in size.
	136	*/
	137	int xprt_setup_backchannel(struct rpc_xprt *xprt, unsigned int min_reqs)
	138	{
1dddda86	139	struct rpc_rqst *req;
fb7a0b9a RL	140	struct list_head tmp_list;
	141	int i;
	142
	143	dprintk("RPC: setup backchannel transport\n");
	144
	145	/*
	146	* We use a temporary list to keep track of the preallocated
	147	* buffers. Once we're done building the list we splice it
	148	* into the backchannel preallocation list off of the rpc_xprt
	149	* struct. This helps minimize the amount of time the list
	150	* lock is held on the rpc_xprt struct. It also makes cleanup
	151	* easier in case of memory allocation errors.
	152	*/
	153	INIT_LIST_HEAD(&tmp_list);
	154	for (i = 0; i < min_reqs; i++) {
	155	/* Pre-allocate one backchannel rpc_rqst */
1dddda86	156	req = xprt_alloc_bc_req(xprt, GFP_KERNEL);
fb7a0b9a RL	157	if (req == NULL) {
	158	printk(KERN_ERR "Failed to create bc rpc_rqst\n");
	159	goto out_free;
	160	}
	161
	162	/* Add the allocated buffer to the tmp list */
	163	dprintk("RPC: adding req= %p\n", req);
	164	list_add(&req->rq_bc_pa_list, &tmp_list);
fb7a0b9a RL	165	}
	166
	167	/*
	168	* Add the temporary list to the backchannel preallocation list
	169	*/
	170	spin_lock_bh(&xprt->bc_pa_lock);
	171	list_splice(&tmp_list, &xprt->bc_pa_list);
	172	xprt_inc_alloc_count(xprt, min_reqs);
	173	spin_unlock_bh(&xprt->bc_pa_lock);
	174
	175	dprintk("RPC: setup backchannel transport done\n");
	176	return 0;
	177
	178	out_free:
	179	/*
	180	* Memory allocation failed, free the temporary list
	181	*/
1dddda86 TM	182	while (!list_empty(&tmp_list)) {
	183	req = list_first_entry(&tmp_list,
	184	struct rpc_rqst,
	185	rq_bc_pa_list);
62835679	186	list_del(&req->rq_bc_pa_list);
fb7a0b9a	187	xprt_free_allocation(req);
62835679	188	}
fb7a0b9a RL	189
fb7a0b9a RL	190	dprintk("RPC: setup backchannel transport failed\n");
d24bab93	191	return -ENOMEM;
fb7a0b9a	192	}
0d961aa9	193	EXPORT_SYMBOL_GPL(xprt_setup_backchannel);
fb7a0b9a	194
2c53040f BH	195	/**
	196	* xprt_destroy_backchannel - Destroys the backchannel preallocated structures.
	197	* @xprt: the transport holding the preallocated strucures
	198	* @max_reqs the maximum number of preallocated structures to destroy
	199	*
fb7a0b9a RL	200	* Since these structures may have been allocated by multiple calls
	201	* to xprt_setup_backchannel, we only destroy up to the maximum number
	202	* of reqs specified by the caller.
fb7a0b9a RL	203	*/
	204	void xprt_destroy_backchannel(struct rpc_xprt *xprt, unsigned int max_reqs)
	205	{
	206	struct rpc_rqst req = NULL, tmp = NULL;
	207
	208	dprintk("RPC: destroy backchannel transport\n");
	209
c4ded8d9 WAA	210	if (max_reqs == 0)
	211	goto out;
	212
fb7a0b9a RL	213	spin_lock_bh(&xprt->bc_pa_lock);
	214	xprt_dec_alloc_count(xprt, max_reqs);
	215	list_for_each_entry_safe(req, tmp, &xprt->bc_pa_list, rq_bc_pa_list) {
	216	dprintk("RPC: req=%p\n", req);
62835679	217	list_del(&req->rq_bc_pa_list);
fb7a0b9a RL	218	xprt_free_allocation(req);
	219	if (--max_reqs == 0)
	220	break;
	221	}
	222	spin_unlock_bh(&xprt->bc_pa_lock);
	223
c4ded8d9	224	out:
fb7a0b9a RL	225	dprintk("RPC: backchannel list empty= %s\n",
	226	list_empty(&xprt->bc_pa_list) ? "true" : "false");
	227	}
0d961aa9	228	EXPORT_SYMBOL_GPL(xprt_destroy_backchannel);
fb7a0b9a	229
2ea24497	230	static struct rpc_rqst xprt_alloc_bc_request(struct rpc_xprt xprt, __be32 xid)
fb7a0b9a	231	{
2ea24497	232	struct rpc_rqst *req = NULL;
fb7a0b9a RL	233
fb7a0b9a RL	234	dprintk("RPC: allocate a backchannel request\n");
2ea24497 TM	235	if (list_empty(&xprt->bc_pa_list))
2ea24497 TM	236	goto not_found;
fb7a0b9a	237
2ea24497 TM	238	req = list_first_entry(&xprt->bc_pa_list, struct rpc_rqst,
	239	rq_bc_pa_list);
	240	req->rq_reply_bytes_recvd = 0;
	241	req->rq_bytes_sent = 0;
	242	memcpy(&req->rq_private_buf, &req->rq_rcv_buf,
fb7a0b9a	243	sizeof(req->rq_private_buf));
2ea24497 TM	244	req->rq_xid = xid;
	245	req->rq_connect_cookie = xprt->connect_cookie;
	246	not_found:
fb7a0b9a RL	247	dprintk("RPC: backchannel req=%p\n", req);
	248	return req;
	249	}
	250
	251	/*
	252	* Return the preallocated rpc_rqst structure and XDR buffers
	253	* associated with this rpc_task.
	254	*/
	255	void xprt_free_bc_request(struct rpc_rqst *req)
	256	{
	257	struct rpc_xprt *xprt = req->rq_xprt;
	258
	259	dprintk("RPC: free backchannel req=%p\n", req);
	260
2ea24497	261	req->rq_connect_cookie = xprt->connect_cookie - 1;
4e857c58	262	smp_mb__before_atomic();
f30dfbba	263	WARN_ON_ONCE(!test_bit(RPC_BC_PA_IN_USE, &req->rq_bc_pa_state));
fb7a0b9a	264	clear_bit(RPC_BC_PA_IN_USE, &req->rq_bc_pa_state);
4e857c58	265	smp_mb__after_atomic();
fb7a0b9a RL	266
	267	if (!xprt_need_to_requeue(xprt)) {
	268	/*
	269	* The last remaining session was destroyed while this
	270	* entry was in use. Free the entry and don't attempt
	271	* to add back to the list because there is no need to
	272	* have anymore preallocated entries.
	273	*/
	274	dprintk("RPC: Last session removed req=%p\n", req);
	275	xprt_free_allocation(req);
	276	return;
	277	}
	278
	279	/*
	280	* Return it to the list of preallocations so that it
	281	* may be reused by a new callback request.
	282	*/
	283	spin_lock_bh(&xprt->bc_pa_lock);
2ea24497	284	list_add_tail(&req->rq_bc_pa_list, &xprt->bc_pa_list);
fb7a0b9a RL	285	spin_unlock_bh(&xprt->bc_pa_lock);
	286	}
	287
2ea24497 TM	288	/*
	289	* One or more rpc_rqst structure have been preallocated during the
	290	* backchannel setup. Buffer space for the send and private XDR buffers
	291	* has been preallocated as well. Use xprt_alloc_bc_request to allocate
	292	* to this request. Use xprt_free_bc_request to return it.
	293	*
	294	* We know that we're called in soft interrupt context, grab the spin_lock
	295	* since there is no need to grab the bottom half spin_lock.
	296	*
	297	* Return an available rpc_rqst, otherwise NULL if non are available.
	298	*/
	299	struct rpc_rqst xprt_lookup_bc_request(struct rpc_xprt xprt, __be32 xid)
	300	{
	301	struct rpc_rqst *req;
	302
	303	spin_lock(&xprt->bc_pa_lock);
	304	list_for_each_entry(req, &xprt->bc_pa_list, rq_bc_pa_list) {
	305	if (req->rq_connect_cookie != xprt->connect_cookie)
	306	continue;
	307	if (req->rq_xid == xid)
	308	goto found;
	309	}
	310	req = xprt_alloc_bc_request(xprt, xid);
	311	found:
	312	spin_unlock(&xprt->bc_pa_lock);
	313	return req;
	314	}
	315
	316	/*
	317	* Add callback request to callback list. The callback
	318	* service sleeps on the sv_cb_waitq waiting for new
	319	* requests. Wake it up after adding enqueing the
	320	* request.
	321	*/
	322	void xprt_complete_bc_request(struct rpc_rqst *req, uint32_t copied)
	323	{
	324	struct rpc_xprt *xprt = req->rq_xprt;
	325	struct svc_serv *bc_serv = xprt->bc_serv;
	326
813b00d6 CL	327	spin_lock(&xprt->bc_pa_lock);
	328	list_del(&req->rq_bc_pa_list);
	329	spin_unlock(&xprt->bc_pa_lock);
	330
2ea24497 TM	331	req->rq_private_buf.len = copied;
	332	set_bit(RPC_BC_PA_IN_USE, &req->rq_bc_pa_state);
	333
	334	dprintk("RPC: add callback request to list\n");
	335	spin_lock(&bc_serv->sv_cb_lock);
2ea24497 TM	336	list_add(&req->rq_bc_list, &bc_serv->sv_cb_list);
	337	wake_up(&bc_serv->sv_cb_waitq);
	338	spin_unlock(&bc_serv->sv_cb_lock);
	339	}
	340