[deliverable/linux.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/sunrpc/xprt.h>

#ifdef RPC_DEBUG
#define RPCDBG_FACILITY	RPCDBG_TRANS
#endif

#if defined(CONFIG_NFS_V4_1)

/*
 * 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);
	BUG_ON(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 -1;
}
EXPORT_SYMBOL(xprt_setup_backchannel);

/*
 * Destroys the backchannel preallocated structures.
 * 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.
 * @xprt:	the transport holding the preallocated strucures
 * @max_reqs	the maximum number of preallocated structures to destroy
 */
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");

	BUG_ON(max_reqs == 0);
	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);

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

#endif /* CONFIG_NFS_V4_1 */
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>
	25	#include <linux/sunrpc/xprt.h>
	26
	27	#ifdef RPC_DEBUG
	28	#define RPCDBG_FACILITY RPCDBG_TRANS
	29	#endif
	30
	31	#if defined(CONFIG_NFS_V4_1)
	32
	33	/*
	34	* Helper routines that track the number of preallocation elements
	35	* on the transport.
	36	*/
	37	static inline int xprt_need_to_requeue(struct rpc_xprt *xprt)
	38	{
	39	return xprt->bc_alloc_count > 0;
	40	}
	41
	42	static inline void xprt_inc_alloc_count(struct rpc_xprt *xprt, unsigned int n)
	43	{
	44	xprt->bc_alloc_count += n;
	45	}
	46
	47	static inline int xprt_dec_alloc_count(struct rpc_xprt *xprt, unsigned int n)
	48	{
	49	return xprt->bc_alloc_count -= n;
	50	}
	51
	52	/*
	53	* Free the preallocated rpc_rqst structure and the memory
	54	* buffers hanging off of it.
	55	*/
	56	static void xprt_free_allocation(struct rpc_rqst *req)
	57	{
	58	struct xdr_buf *xbufp;
	59
	60	dprintk("RPC: free allocations for req= %p\n", req);
	61	BUG_ON(test_bit(RPC_BC_PA_IN_USE, &req->rq_bc_pa_state));
	62	xbufp = &req->rq_private_buf;
	63	free_page((unsigned long)xbufp->head[0].iov_base);
	64	xbufp = &req->rq_snd_buf;
65	free_page((unsigned long)xbufp->head[0].iov_base);
66	list_del(&req->rq_bc_pa_list);
67	kfree(req);
68	}
69
70	/*
71	* Preallocate up to min_reqs structures and related buffers for use
72	* by the backchannel. This function can be called multiple times
73	* when creating new sessions that use the same rpc_xprt. The
74	* preallocated buffers are added to the pool of resources used by
75	* the rpc_xprt. Anyone of these resources may be used used by an
76	* incoming callback request. It's up to the higher levels in the
77	* stack to enforce that the maximum number of session slots is not
78	* being exceeded.
79	*
80	* Some callback arguments can be large. For example, a pNFS server
81	* using multiple deviceids. The list can be unbound, but the client
82	* has the ability to tell the server the maximum size of the callback
83	* requests. Each deviceID is 16 bytes, so allocate one page
84	* for the arguments to have enough room to receive a number of these
85	* deviceIDs. The NFS client indicates to the pNFS server that its
86	* callback requests can be up to 4096 bytes in size.
87	*/
88	int xprt_setup_backchannel(struct rpc_xprt *xprt, unsigned int min_reqs)
89	{
90	struct page page_rcv = NULL, page_snd = NULL;
91	struct xdr_buf *xbufp = NULL;
92	struct rpc_rqst req, tmp;
93	struct list_head tmp_list;
94	int i;
95
96	dprintk("RPC: setup backchannel transport\n");
97
98	/*
99	* We use a temporary list to keep track of the preallocated
100	* buffers. Once we're done building the list we splice it
101	* into the backchannel preallocation list off of the rpc_xprt
102	* struct. This helps minimize the amount of time the list
103	* lock is held on the rpc_xprt struct. It also makes cleanup
104	* easier in case of memory allocation errors.
105	*/
106	INIT_LIST_HEAD(&tmp_list);
107	for (i = 0; i < min_reqs; i++) {
108	/* Pre-allocate one backchannel rpc_rqst */
109	req = kzalloc(sizeof(struct rpc_rqst), GFP_KERNEL);
110	if (req == NULL) {
111	printk(KERN_ERR "Failed to create bc rpc_rqst\n");
112	goto out_free;
113	}
114
115	/* Add the allocated buffer to the tmp list */
116	dprintk("RPC: adding req= %p\n", req);
117	list_add(&req->rq_bc_pa_list, &tmp_list);
118
119	req->rq_xprt = xprt;
120	INIT_LIST_HEAD(&req->rq_list);
121	INIT_LIST_HEAD(&req->rq_bc_list);
122
123	/* Preallocate one XDR receive buffer */
124	page_rcv = alloc_page(GFP_KERNEL);
125	if (page_rcv == NULL) {
126	printk(KERN_ERR "Failed to create bc receive xbuf\n");
127	goto out_free;
128	}
129	xbufp = &req->rq_rcv_buf;
130	xbufp->head[0].iov_base = page_address(page_rcv);
131	xbufp->head[0].iov_len = PAGE_SIZE;
132	xbufp->tail[0].iov_base = NULL;
133	xbufp->tail[0].iov_len = 0;
134	xbufp->page_len = 0;
135	xbufp->len = PAGE_SIZE;
136	xbufp->buflen = PAGE_SIZE;
137
138	/* Preallocate one XDR send buffer */
139	page_snd = alloc_page(GFP_KERNEL);
140	if (page_snd == NULL) {
141	printk(KERN_ERR "Failed to create bc snd xbuf\n");
142	goto out_free;
143	}
144
145	xbufp = &req->rq_snd_buf;
146	xbufp->head[0].iov_base = page_address(page_snd);
147	xbufp->head[0].iov_len = 0;
148	xbufp->tail[0].iov_base = NULL;
149	xbufp->tail[0].iov_len = 0;
150	xbufp->page_len = 0;
151	xbufp->len = 0;
152	xbufp->buflen = PAGE_SIZE;
153	}
154
155	/*
156	* Add the temporary list to the backchannel preallocation list
157	*/
158	spin_lock_bh(&xprt->bc_pa_lock);
159	list_splice(&tmp_list, &xprt->bc_pa_list);
160	xprt_inc_alloc_count(xprt, min_reqs);
161	spin_unlock_bh(&xprt->bc_pa_lock);
162
163	dprintk("RPC: setup backchannel transport done\n");
164	return 0;
165
166	out_free:
167	/*
168	* Memory allocation failed, free the temporary list
169	*/
170	list_for_each_entry_safe(req, tmp, &tmp_list, rq_bc_pa_list)
171	xprt_free_allocation(req);
172
173	dprintk("RPC: setup backchannel transport failed\n");
174	return -1;
175	}
176	EXPORT_SYMBOL(xprt_setup_backchannel);
177
178	/*
179	* Destroys the backchannel preallocated structures.
180	* Since these structures may have been allocated by multiple calls
181	* to xprt_setup_backchannel, we only destroy up to the maximum number
182	* of reqs specified by the caller.
183	* @xprt: the transport holding the preallocated strucures
184	* @max_reqs the maximum number of preallocated structures to destroy
185	*/
186	void xprt_destroy_backchannel(struct rpc_xprt *xprt, unsigned int max_reqs)
187	{
188	struct rpc_rqst req = NULL, tmp = NULL;
189
190	dprintk("RPC: destroy backchannel transport\n");
191
192	BUG_ON(max_reqs == 0);
193	spin_lock_bh(&xprt->bc_pa_lock);
194	xprt_dec_alloc_count(xprt, max_reqs);
195	list_for_each_entry_safe(req, tmp, &xprt->bc_pa_list, rq_bc_pa_list) {
196	dprintk("RPC: req=%p\n", req);
197	xprt_free_allocation(req);
198	if (--max_reqs == 0)
199	break;
200	}
201	spin_unlock_bh(&xprt->bc_pa_lock);
202
203	dprintk("RPC: backchannel list empty= %s\n",
204	list_empty(&xprt->bc_pa_list) ? "true" : "false");
205	}
206	EXPORT_SYMBOL(xprt_destroy_backchannel);
207
208	/*
209	* One or more rpc_rqst structure have been preallocated during the
210	* backchannel setup. Buffer space for the send and private XDR buffers
211	* has been preallocated as well. Use xprt_alloc_bc_request to allocate
212	* to this request. Use xprt_free_bc_request to return it.
213	*
e9f02985 RL	214	* We know that we're called in soft interrupt context, grab the spin_lock
	215	* since there is no need to grab the bottom half spin_lock.
	216	*
fb7a0b9a RL	217	* Return an available rpc_rqst, otherwise NULL if non are available.
	218	*/
	219	struct rpc_rqst xprt_alloc_bc_request(struct rpc_xprt xprt)
	220	{
	221	struct rpc_rqst *req;
	222
	223	dprintk("RPC: allocate a backchannel request\n");
e9f02985	224	spin_lock(&xprt->bc_pa_lock);
fb7a0b9a RL	225	if (!list_empty(&xprt->bc_pa_list)) {
	226	req = list_first_entry(&xprt->bc_pa_list, struct rpc_rqst,
	227	rq_bc_pa_list);
	228	list_del(&req->rq_bc_pa_list);
	229	} else {
	230	req = NULL;
	231	}
e9f02985	232	spin_unlock(&xprt->bc_pa_lock);
fb7a0b9a RL	233
	234	if (req != NULL) {
	235	set_bit(RPC_BC_PA_IN_USE, &req->rq_bc_pa_state);
dd2b63d0	236	req->rq_reply_bytes_recvd = 0;
fb7a0b9a RL	237	req->rq_bytes_sent = 0;
	238	memcpy(&req->rq_private_buf, &req->rq_rcv_buf,
	239	sizeof(req->rq_private_buf));
	240	}
	241	dprintk("RPC: backchannel req=%p\n", req);
	242	return req;
	243	}
	244
	245	/*
	246	* Return the preallocated rpc_rqst structure and XDR buffers
	247	* associated with this rpc_task.
	248	*/
	249	void xprt_free_bc_request(struct rpc_rqst *req)
	250	{
	251	struct rpc_xprt *xprt = req->rq_xprt;
	252
	253	dprintk("RPC: free backchannel req=%p\n", req);
	254
	255	smp_mb__before_clear_bit();
	256	BUG_ON(!test_bit(RPC_BC_PA_IN_USE, &req->rq_bc_pa_state));
	257	clear_bit(RPC_BC_PA_IN_USE, &req->rq_bc_pa_state);
	258	smp_mb__after_clear_bit();
	259
	260	if (!xprt_need_to_requeue(xprt)) {
	261	/*
	262	* The last remaining session was destroyed while this
	263	* entry was in use. Free the entry and don't attempt
	264	* to add back to the list because there is no need to
	265	* have anymore preallocated entries.
	266	*/
	267	dprintk("RPC: Last session removed req=%p\n", req);
	268	xprt_free_allocation(req);
	269	return;
	270	}
	271
	272	/*
	273	* Return it to the list of preallocations so that it
	274	* may be reused by a new callback request.
	275	*/
	276	spin_lock_bh(&xprt->bc_pa_lock);
	277	list_add(&req->rq_bc_pa_list, &xprt->bc_pa_list);
	278	spin_unlock_bh(&xprt->bc_pa_lock);
	279	}
	280
	281	#endif /* CONFIG_NFS_V4_1 */