[mirror_ubuntu-zesty-kernel.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>

#ifdef RPC_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_private_buf;
	free_page((unsigned long)xbufp->head[0].iov_base);
	xbufp = &req->rq_snd_buf;
	free_page((unsigned long)xbufp->head[0].iov_base);
	list_del(&req->rq_bc_pa_list);
	kfree(req);
}

/*
 * 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 page *page_rcv = NULL, *page_snd = NULL;
	struct xdr_buf *xbufp = NULL;
	struct rpc_rqst *req, *tmp;
	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 = kzalloc(sizeof(struct rpc_rqst), 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);

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

		/* Preallocate one XDR receive buffer */
		page_rcv = alloc_page(GFP_KERNEL);
		if (page_rcv == NULL) {
			printk(KERN_ERR "Failed to create bc receive xbuf\n");
			goto out_free;
		}
		xbufp = &req->rq_rcv_buf;
		xbufp->head[0].iov_base = page_address(page_rcv);
		xbufp->head[0].iov_len = PAGE_SIZE;
		xbufp->tail[0].iov_base = NULL;
		xbufp->tail[0].iov_len = 0;
		xbufp->page_len = 0;
		xbufp->len = PAGE_SIZE;
		xbufp->buflen = PAGE_SIZE;

		/* Preallocate one XDR send buffer */
		page_snd = alloc_page(GFP_KERNEL);
		if (page_snd == NULL) {
			printk(KERN_ERR "Failed to create bc snd xbuf\n");
			goto out_free;
		}

		xbufp = &req->rq_snd_buf;
		xbufp->head[0].iov_base = page_address(page_snd);
		xbufp->head[0].iov_len = 0;
		xbufp->tail[0].iov_base = NULL;
		xbufp->tail[0].iov_len = 0;
		xbufp->page_len = 0;
		xbufp->len = 0;
		xbufp->buflen = PAGE_SIZE;
	}

	/*
	 * 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
	 */
	list_for_each_entry_safe(req, tmp, &tmp_list, 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);
		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);

/*
 * 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_alloc_bc_request(struct rpc_xprt *xprt)
{
	struct rpc_rqst *req;

	dprintk("RPC:       allocate a backchannel request\n");
	spin_lock(&xprt->bc_pa_lock);
	if (!list_empty(&xprt->bc_pa_list)) {
		req = list_first_entry(&xprt->bc_pa_list, struct rpc_rqst,
				rq_bc_pa_list);
		list_del(&req->rq_bc_pa_list);
	} else {
		req = NULL;
	}
	spin_unlock(&xprt->bc_pa_lock);

	if (req != NULL) {
		set_bit(RPC_BC_PA_IN_USE, &req->rq_bc_pa_state);
		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));
	}
	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);

	smp_mb__before_clear_bit();
	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_clear_bit();

	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(&req->rq_bc_pa_list, &xprt->bc_pa_list);
	spin_unlock_bh(&xprt->bc_pa_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 RL	29
	30	#ifdef RPC_DEBUG
	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));
fb7a0b9a RL	63	xbufp = &req->rq_private_buf;
	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);
	67	list_del(&req->rq_bc_pa_list);
	68	kfree(req);
	69	}
	70
	71	/*
	72	* Preallocate up to min_reqs structures and related buffers for use
	73	* by the backchannel. This function can be called multiple times
	74	* when creating new sessions that use the same rpc_xprt. The
	75	* preallocated buffers are added to the pool of resources used by
	76	* the rpc_xprt. Anyone of these resources may be used used by an
	77	* incoming callback request. It's up to the higher levels in the
	78	* stack to enforce that the maximum number of session slots is not
	79	* being exceeded.
	80	*
	81	* Some callback arguments can be large. For example, a pNFS server
	82	* using multiple deviceids. The list can be unbound, but the client
	83	* has the ability to tell the server the maximum size of the callback
	84	* requests. Each deviceID is 16 bytes, so allocate one page
	85	* for the arguments to have enough room to receive a number of these
	86	* deviceIDs. The NFS client indicates to the pNFS server that its
	87	* callback requests can be up to 4096 bytes in size.
	88	*/
	89	int xprt_setup_backchannel(struct rpc_xprt *xprt, unsigned int min_reqs)
	90	{
	91	struct page page_rcv = NULL, page_snd = NULL;
	92	struct xdr_buf *xbufp = NULL;
	93	struct rpc_rqst req, tmp;
	94	struct list_head tmp_list;
	95	int i;
	96
	97	dprintk("RPC: setup backchannel transport\n");
	98
	99	/*
	100	* We use a temporary list to keep track of the preallocated
	101	* buffers. Once we're done building the list we splice it
	102	* into the backchannel preallocation list off of the rpc_xprt
	103	* struct. This helps minimize the amount of time the list
	104	* lock is held on the rpc_xprt struct. It also makes cleanup
	105	* easier in case of memory allocation errors.
	106	*/
	107	INIT_LIST_HEAD(&tmp_list);
	108	for (i = 0; i < min_reqs; i++) {
	109	/* Pre-allocate one backchannel rpc_rqst */
	110	req = kzalloc(sizeof(struct rpc_rqst), GFP_KERNEL);
	111	if (req == NULL) {
	112	printk(KERN_ERR "Failed to create bc rpc_rqst\n");
	113	goto out_free;
	114	}
	115
	116	/* Add the allocated buffer to the tmp list */
	117	dprintk("RPC: adding req= %p\n", req);
	118	list_add(&req->rq_bc_pa_list, &tmp_list);
	119
	120	req->rq_xprt = xprt;
	121	INIT_LIST_HEAD(&req->rq_list);
	122	INIT_LIST_HEAD(&req->rq_bc_list);
	123
	124	/* Preallocate one XDR receive buffer */
	125	page_rcv = alloc_page(GFP_KERNEL);
	126	if (page_rcv == NULL) {
127	printk(KERN_ERR "Failed to create bc receive xbuf\n");
128	goto out_free;
129	}
130	xbufp = &req->rq_rcv_buf;
131	xbufp->head[0].iov_base = page_address(page_rcv);
132	xbufp->head[0].iov_len = PAGE_SIZE;
133	xbufp->tail[0].iov_base = NULL;
134	xbufp->tail[0].iov_len = 0;
135	xbufp->page_len = 0;
136	xbufp->len = PAGE_SIZE;
137	xbufp->buflen = PAGE_SIZE;
138
139	/* Preallocate one XDR send buffer */
140	page_snd = alloc_page(GFP_KERNEL);
141	if (page_snd == NULL) {
142	printk(KERN_ERR "Failed to create bc snd xbuf\n");
143	goto out_free;
144	}
145
146	xbufp = &req->rq_snd_buf;
147	xbufp->head[0].iov_base = page_address(page_snd);
148	xbufp->head[0].iov_len = 0;
149	xbufp->tail[0].iov_base = NULL;
150	xbufp->tail[0].iov_len = 0;
151	xbufp->page_len = 0;
152	xbufp->len = 0;
153	xbufp->buflen = PAGE_SIZE;
154	}
155
156	/*
157	* Add the temporary list to the backchannel preallocation list
158	*/
159	spin_lock_bh(&xprt->bc_pa_lock);
160	list_splice(&tmp_list, &xprt->bc_pa_list);
161	xprt_inc_alloc_count(xprt, min_reqs);
162	spin_unlock_bh(&xprt->bc_pa_lock);
163
164	dprintk("RPC: setup backchannel transport done\n");
165	return 0;
166
167	out_free:
168	/*
169	* Memory allocation failed, free the temporary list
170	*/
171	list_for_each_entry_safe(req, tmp, &tmp_list, rq_bc_pa_list)
172	xprt_free_allocation(req);
173
174	dprintk("RPC: setup backchannel transport failed\n");
d24bab93	175	return -ENOMEM;
fb7a0b9a	176	}
0d961aa9	177	EXPORT_SYMBOL_GPL(xprt_setup_backchannel);
fb7a0b9a	178
2c53040f BH	179	/**
	180	* xprt_destroy_backchannel - Destroys the backchannel preallocated structures.
	181	* @xprt: the transport holding the preallocated strucures
	182	* @max_reqs the maximum number of preallocated structures to destroy
	183	*
fb7a0b9a RL	184	* Since these structures may have been allocated by multiple calls
	185	* to xprt_setup_backchannel, we only destroy up to the maximum number
	186	* of reqs specified by the caller.
fb7a0b9a RL	187	*/
	188	void xprt_destroy_backchannel(struct rpc_xprt *xprt, unsigned int max_reqs)
	189	{
	190	struct rpc_rqst req = NULL, tmp = NULL;
	191
	192	dprintk("RPC: destroy backchannel transport\n");
	193
c4ded8d9 WAA	194	if (max_reqs == 0)
	195	goto out;
	196
fb7a0b9a RL	197	spin_lock_bh(&xprt->bc_pa_lock);
	198	xprt_dec_alloc_count(xprt, max_reqs);
	199	list_for_each_entry_safe(req, tmp, &xprt->bc_pa_list, rq_bc_pa_list) {
	200	dprintk("RPC: req=%p\n", req);
	201	xprt_free_allocation(req);
	202	if (--max_reqs == 0)
	203	break;
	204	}
	205	spin_unlock_bh(&xprt->bc_pa_lock);
	206
c4ded8d9	207	out:
fb7a0b9a RL	208	dprintk("RPC: backchannel list empty= %s\n",
	209	list_empty(&xprt->bc_pa_list) ? "true" : "false");
	210	}
0d961aa9	211	EXPORT_SYMBOL_GPL(xprt_destroy_backchannel);
fb7a0b9a RL	212
	213	/*
	214	* One or more rpc_rqst structure have been preallocated during the
	215	* backchannel setup. Buffer space for the send and private XDR buffers
	216	* has been preallocated as well. Use xprt_alloc_bc_request to allocate
	217	* to this request. Use xprt_free_bc_request to return it.
	218	*
e9f02985 RL	219	* We know that we're called in soft interrupt context, grab the spin_lock
	220	* since there is no need to grab the bottom half spin_lock.
	221	*
fb7a0b9a RL	222	* Return an available rpc_rqst, otherwise NULL if non are available.
	223	*/
	224	struct rpc_rqst xprt_alloc_bc_request(struct rpc_xprt xprt)
	225	{
	226	struct rpc_rqst *req;
	227
	228	dprintk("RPC: allocate a backchannel request\n");
e9f02985	229	spin_lock(&xprt->bc_pa_lock);
fb7a0b9a RL	230	if (!list_empty(&xprt->bc_pa_list)) {
	231	req = list_first_entry(&xprt->bc_pa_list, struct rpc_rqst,
	232	rq_bc_pa_list);
	233	list_del(&req->rq_bc_pa_list);
	234	} else {
	235	req = NULL;
	236	}
e9f02985	237	spin_unlock(&xprt->bc_pa_lock);
fb7a0b9a RL	238
	239	if (req != NULL) {
	240	set_bit(RPC_BC_PA_IN_USE, &req->rq_bc_pa_state);
dd2b63d0	241	req->rq_reply_bytes_recvd = 0;
fb7a0b9a RL	242	req->rq_bytes_sent = 0;
	243	memcpy(&req->rq_private_buf, &req->rq_rcv_buf,
	244	sizeof(req->rq_private_buf));
	245	}
	246	dprintk("RPC: backchannel req=%p\n", req);
	247	return req;
	248	}
	249
	250	/*
	251	* Return the preallocated rpc_rqst structure and XDR buffers
	252	* associated with this rpc_task.
	253	*/
	254	void xprt_free_bc_request(struct rpc_rqst *req)
	255	{
	256	struct rpc_xprt *xprt = req->rq_xprt;
	257
	258	dprintk("RPC: free backchannel req=%p\n", req);
	259
	260	smp_mb__before_clear_bit();
f30dfbba	261	WARN_ON_ONCE(!test_bit(RPC_BC_PA_IN_USE, &req->rq_bc_pa_state));
fb7a0b9a RL	262	clear_bit(RPC_BC_PA_IN_USE, &req->rq_bc_pa_state);
	263	smp_mb__after_clear_bit();
	264
	265	if (!xprt_need_to_requeue(xprt)) {
	266	/*
	267	* The last remaining session was destroyed while this
	268	* entry was in use. Free the entry and don't attempt
	269	* to add back to the list because there is no need to
	270	* have anymore preallocated entries.
	271	*/
	272	dprintk("RPC: Last session removed req=%p\n", req);
	273	xprt_free_allocation(req);
	274	return;
	275	}
	276
	277	/*
	278	* Return it to the list of preallocations so that it
	279	* may be reused by a new callback request.
	280	*/
	281	spin_lock_bh(&xprt->bc_pa_lock);
	282	list_add(&req->rq_bc_pa_list, &xprt->bc_pa_list);
	283	spin_unlock_bh(&xprt->bc_pa_lock);
	284	}
	285