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/slab.h>
26 #include <linux/sunrpc/xprt.h>
27 #include <linux/export.h>
28 #include <linux/sunrpc/bc_xprt.h>
29
30 #ifdef RPC_DEBUG
31 #define RPCDBG_FACILITY RPCDBG_TRANS
32 #endif
33
34 /*
35 * Helper routines that track the number of preallocation elements
36 * on the transport.
37 */
xprt_need_to_requeue(struct rpc_xprt * xprt)38 static inline int xprt_need_to_requeue(struct rpc_xprt *xprt)
39 {
40 return xprt->bc_alloc_count > 0;
41 }
42
xprt_inc_alloc_count(struct rpc_xprt * xprt,unsigned int n)43 static inline void xprt_inc_alloc_count(struct rpc_xprt *xprt, unsigned int n)
44 {
45 xprt->bc_alloc_count += n;
46 }
47
xprt_dec_alloc_count(struct rpc_xprt * xprt,unsigned int n)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 */
xprt_free_allocation(struct rpc_rqst * req)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);
62 BUG_ON(test_bit(RPC_BC_PA_IN_USE, &req->rq_bc_pa_state));
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 */
xprt_setup_backchannel(struct rpc_xprt * xprt,unsigned int min_reqs)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");
175 return -1;
176 }
177 EXPORT_SYMBOL_GPL(xprt_setup_backchannel);
178
179 /*
180 * Destroys the backchannel preallocated structures.
181 * Since these structures may have been allocated by multiple calls
182 * to xprt_setup_backchannel, we only destroy up to the maximum number
183 * of reqs specified by the caller.
184 * @xprt: the transport holding the preallocated strucures
185 * @max_reqs the maximum number of preallocated structures to destroy
186 */
xprt_destroy_backchannel(struct rpc_xprt * xprt,unsigned int max_reqs)187 void xprt_destroy_backchannel(struct rpc_xprt *xprt, unsigned int max_reqs)
188 {
189 struct rpc_rqst *req = NULL, *tmp = NULL;
190
191 dprintk("RPC: destroy backchannel transport\n");
192
193 BUG_ON(max_reqs == 0);
194 spin_lock_bh(&xprt->bc_pa_lock);
195 xprt_dec_alloc_count(xprt, max_reqs);
196 list_for_each_entry_safe(req, tmp, &xprt->bc_pa_list, rq_bc_pa_list) {
197 dprintk("RPC: req=%p\n", req);
198 xprt_free_allocation(req);
199 if (--max_reqs == 0)
200 break;
201 }
202 spin_unlock_bh(&xprt->bc_pa_lock);
203
204 dprintk("RPC: backchannel list empty= %s\n",
205 list_empty(&xprt->bc_pa_list) ? "true" : "false");
206 }
207 EXPORT_SYMBOL_GPL(xprt_destroy_backchannel);
208
209 /*
210 * One or more rpc_rqst structure have been preallocated during the
211 * backchannel setup. Buffer space for the send and private XDR buffers
212 * has been preallocated as well. Use xprt_alloc_bc_request to allocate
213 * to this request. Use xprt_free_bc_request to return it.
214 *
215 * We know that we're called in soft interrupt context, grab the spin_lock
216 * since there is no need to grab the bottom half spin_lock.
217 *
218 * Return an available rpc_rqst, otherwise NULL if non are available.
219 */
xprt_alloc_bc_request(struct rpc_xprt * xprt)220 struct rpc_rqst *xprt_alloc_bc_request(struct rpc_xprt *xprt)
221 {
222 struct rpc_rqst *req;
223
224 dprintk("RPC: allocate a backchannel request\n");
225 spin_lock(&xprt->bc_pa_lock);
226 if (!list_empty(&xprt->bc_pa_list)) {
227 req = list_first_entry(&xprt->bc_pa_list, struct rpc_rqst,
228 rq_bc_pa_list);
229 list_del(&req->rq_bc_pa_list);
230 } else {
231 req = NULL;
232 }
233 spin_unlock(&xprt->bc_pa_lock);
234
235 if (req != NULL) {
236 set_bit(RPC_BC_PA_IN_USE, &req->rq_bc_pa_state);
237 req->rq_reply_bytes_recvd = 0;
238 req->rq_bytes_sent = 0;
239 memcpy(&req->rq_private_buf, &req->rq_rcv_buf,
240 sizeof(req->rq_private_buf));
241 }
242 dprintk("RPC: backchannel req=%p\n", req);
243 return req;
244 }
245
246 /*
247 * Return the preallocated rpc_rqst structure and XDR buffers
248 * associated with this rpc_task.
249 */
xprt_free_bc_request(struct rpc_rqst * req)250 void xprt_free_bc_request(struct rpc_rqst *req)
251 {
252 struct rpc_xprt *xprt = req->rq_xprt;
253
254 dprintk("RPC: free backchannel req=%p\n", req);
255
256 smp_mb__before_clear_bit();
257 BUG_ON(!test_bit(RPC_BC_PA_IN_USE, &req->rq_bc_pa_state));
258 clear_bit(RPC_BC_PA_IN_USE, &req->rq_bc_pa_state);
259 smp_mb__after_clear_bit();
260
261 if (!xprt_need_to_requeue(xprt)) {
262 /*
263 * The last remaining session was destroyed while this
264 * entry was in use. Free the entry and don't attempt
265 * to add back to the list because there is no need to
266 * have anymore preallocated entries.
267 */
268 dprintk("RPC: Last session removed req=%p\n", req);
269 xprt_free_allocation(req);
270 return;
271 }
272
273 /*
274 * Return it to the list of preallocations so that it
275 * may be reused by a new callback request.
276 */
277 spin_lock_bh(&xprt->bc_pa_lock);
278 list_add(&req->rq_bc_pa_list, &xprt->bc_pa_list);
279 spin_unlock_bh(&xprt->bc_pa_lock);
280 }
281
282