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Ricardo Labiagafb7a0b92009-04-01 09:23:00 -04001/******************************************************************************
2
3(c) 2007 Network Appliance, Inc. All Rights Reserved.
4(c) 2009 NetApp. All Rights Reserved.
5
6NetApp provides this source code under the GPL v2 License.
7The GPL v2 license is available at
8http://opensource.org/licenses/gpl-license.php.
9
10THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
11"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
12LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
13A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
14CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
15EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
16PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
17PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
18LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
19NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
20SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
21
22******************************************************************************/
23
24#include <linux/tcp.h>
Tejun Heo5a0e3ad2010-03-24 17:04:11 +090025#include <linux/slab.h>
Ricardo Labiagafb7a0b92009-04-01 09:23:00 -040026#include <linux/sunrpc/xprt.h>
Paul Gortmakerbc3b2d72011-07-15 11:47:34 -040027#include <linux/export.h>
Trond Myklebust09acfea2012-03-11 15:22:54 -040028#include <linux/sunrpc/bc_xprt.h>
Ricardo Labiagafb7a0b92009-04-01 09:23:00 -040029
30#ifdef RPC_DEBUG
31#define RPCDBG_FACILITY RPCDBG_TRANS
32#endif
33
Ricardo Labiagafb7a0b92009-04-01 09:23:00 -040034/*
35 * Helper routines that track the number of preallocation elements
36 * on the transport.
37 */
38static inline int xprt_need_to_requeue(struct rpc_xprt *xprt)
39{
40 return xprt->bc_alloc_count > 0;
41}
42
43static inline void xprt_inc_alloc_count(struct rpc_xprt *xprt, unsigned int n)
44{
45 xprt->bc_alloc_count += n;
46}
47
48static 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 */
57static 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);
Weston Andros Adamsonf30dfbb2012-10-23 10:43:33 -040062 WARN_ON_ONCE(test_bit(RPC_BC_PA_IN_USE, &req->rq_bc_pa_state));
Ricardo Labiagafb7a0b92009-04-01 09:23:00 -040063 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);
Ricardo Labiagafb7a0b92009-04-01 09:23:00 -040067 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 */
88int 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
166out_free:
167 /*
168 * Memory allocation failed, free the temporary list
169 */
Trond Myklebust62835672014-02-11 13:56:54 -0500170 list_for_each_entry_safe(req, tmp, &tmp_list, rq_bc_pa_list) {
171 list_del(&req->rq_bc_pa_list);
Ricardo Labiagafb7a0b92009-04-01 09:23:00 -0400172 xprt_free_allocation(req);
Trond Myklebust62835672014-02-11 13:56:54 -0500173 }
Ricardo Labiagafb7a0b92009-04-01 09:23:00 -0400174
175 dprintk("RPC: setup backchannel transport failed\n");
Weston Andros Adamsond24bab92012-11-01 11:21:53 -0400176 return -ENOMEM;
Ricardo Labiagafb7a0b92009-04-01 09:23:00 -0400177}
Trond Myklebust0d961aa2011-07-13 19:24:15 -0400178EXPORT_SYMBOL_GPL(xprt_setup_backchannel);
Ricardo Labiagafb7a0b92009-04-01 09:23:00 -0400179
Ben Hutchings2c530402012-07-10 10:55:09 +0000180/**
181 * xprt_destroy_backchannel - Destroys the backchannel preallocated structures.
182 * @xprt: the transport holding the preallocated strucures
183 * @max_reqs the maximum number of preallocated structures to destroy
184 *
Ricardo Labiagafb7a0b92009-04-01 09:23:00 -0400185 * Since these structures may have been allocated by multiple calls
186 * to xprt_setup_backchannel, we only destroy up to the maximum number
187 * of reqs specified by the caller.
Ricardo Labiagafb7a0b92009-04-01 09:23:00 -0400188 */
189void xprt_destroy_backchannel(struct rpc_xprt *xprt, unsigned int max_reqs)
190{
191 struct rpc_rqst *req = NULL, *tmp = NULL;
192
193 dprintk("RPC: destroy backchannel transport\n");
194
Weston Andros Adamsonc4ded8d2012-10-23 10:43:34 -0400195 if (max_reqs == 0)
196 goto out;
197
Ricardo Labiagafb7a0b92009-04-01 09:23:00 -0400198 spin_lock_bh(&xprt->bc_pa_lock);
199 xprt_dec_alloc_count(xprt, max_reqs);
200 list_for_each_entry_safe(req, tmp, &xprt->bc_pa_list, rq_bc_pa_list) {
201 dprintk("RPC: req=%p\n", req);
Trond Myklebust62835672014-02-11 13:56:54 -0500202 list_del(&req->rq_bc_pa_list);
Ricardo Labiagafb7a0b92009-04-01 09:23:00 -0400203 xprt_free_allocation(req);
204 if (--max_reqs == 0)
205 break;
206 }
207 spin_unlock_bh(&xprt->bc_pa_lock);
208
Weston Andros Adamsonc4ded8d2012-10-23 10:43:34 -0400209out:
Ricardo Labiagafb7a0b92009-04-01 09:23:00 -0400210 dprintk("RPC: backchannel list empty= %s\n",
211 list_empty(&xprt->bc_pa_list) ? "true" : "false");
212}
Trond Myklebust0d961aa2011-07-13 19:24:15 -0400213EXPORT_SYMBOL_GPL(xprt_destroy_backchannel);
Ricardo Labiagafb7a0b92009-04-01 09:23:00 -0400214
Trond Myklebust2ea24492014-02-10 11:18:39 -0500215static struct rpc_rqst *xprt_alloc_bc_request(struct rpc_xprt *xprt, __be32 xid)
Ricardo Labiagafb7a0b92009-04-01 09:23:00 -0400216{
Trond Myklebust2ea24492014-02-10 11:18:39 -0500217 struct rpc_rqst *req = NULL;
Ricardo Labiagafb7a0b92009-04-01 09:23:00 -0400218
219 dprintk("RPC: allocate a backchannel request\n");
Trond Myklebust2ea24492014-02-10 11:18:39 -0500220 if (list_empty(&xprt->bc_pa_list))
221 goto not_found;
Ricardo Labiagafb7a0b92009-04-01 09:23:00 -0400222
Trond Myklebust2ea24492014-02-10 11:18:39 -0500223 req = list_first_entry(&xprt->bc_pa_list, struct rpc_rqst,
224 rq_bc_pa_list);
225 req->rq_reply_bytes_recvd = 0;
226 req->rq_bytes_sent = 0;
227 memcpy(&req->rq_private_buf, &req->rq_rcv_buf,
Ricardo Labiagafb7a0b92009-04-01 09:23:00 -0400228 sizeof(req->rq_private_buf));
Trond Myklebust2ea24492014-02-10 11:18:39 -0500229 req->rq_xid = xid;
230 req->rq_connect_cookie = xprt->connect_cookie;
231not_found:
Ricardo Labiagafb7a0b92009-04-01 09:23:00 -0400232 dprintk("RPC: backchannel req=%p\n", req);
233 return req;
234}
235
236/*
237 * Return the preallocated rpc_rqst structure and XDR buffers
238 * associated with this rpc_task.
239 */
240void xprt_free_bc_request(struct rpc_rqst *req)
241{
242 struct rpc_xprt *xprt = req->rq_xprt;
243
244 dprintk("RPC: free backchannel req=%p\n", req);
245
Trond Myklebust2ea24492014-02-10 11:18:39 -0500246 req->rq_connect_cookie = xprt->connect_cookie - 1;
Peter Zijlstra4e857c52014-03-17 18:06:10 +0100247 smp_mb__before_atomic();
Weston Andros Adamsonf30dfbb2012-10-23 10:43:33 -0400248 WARN_ON_ONCE(!test_bit(RPC_BC_PA_IN_USE, &req->rq_bc_pa_state));
Ricardo Labiagafb7a0b92009-04-01 09:23:00 -0400249 clear_bit(RPC_BC_PA_IN_USE, &req->rq_bc_pa_state);
Peter Zijlstra4e857c52014-03-17 18:06:10 +0100250 smp_mb__after_atomic();
Ricardo Labiagafb7a0b92009-04-01 09:23:00 -0400251
252 if (!xprt_need_to_requeue(xprt)) {
253 /*
254 * The last remaining session was destroyed while this
255 * entry was in use. Free the entry and don't attempt
256 * to add back to the list because there is no need to
257 * have anymore preallocated entries.
258 */
259 dprintk("RPC: Last session removed req=%p\n", req);
260 xprt_free_allocation(req);
261 return;
262 }
263
264 /*
265 * Return it to the list of preallocations so that it
266 * may be reused by a new callback request.
267 */
268 spin_lock_bh(&xprt->bc_pa_lock);
Trond Myklebust2ea24492014-02-10 11:18:39 -0500269 list_add_tail(&req->rq_bc_pa_list, &xprt->bc_pa_list);
Ricardo Labiagafb7a0b92009-04-01 09:23:00 -0400270 spin_unlock_bh(&xprt->bc_pa_lock);
271}
272
Trond Myklebust2ea24492014-02-10 11:18:39 -0500273/*
274 * One or more rpc_rqst structure have been preallocated during the
275 * backchannel setup. Buffer space for the send and private XDR buffers
276 * has been preallocated as well. Use xprt_alloc_bc_request to allocate
277 * to this request. Use xprt_free_bc_request to return it.
278 *
279 * We know that we're called in soft interrupt context, grab the spin_lock
280 * since there is no need to grab the bottom half spin_lock.
281 *
282 * Return an available rpc_rqst, otherwise NULL if non are available.
283 */
284struct rpc_rqst *xprt_lookup_bc_request(struct rpc_xprt *xprt, __be32 xid)
285{
286 struct rpc_rqst *req;
287
288 spin_lock(&xprt->bc_pa_lock);
289 list_for_each_entry(req, &xprt->bc_pa_list, rq_bc_pa_list) {
290 if (req->rq_connect_cookie != xprt->connect_cookie)
291 continue;
292 if (req->rq_xid == xid)
293 goto found;
294 }
295 req = xprt_alloc_bc_request(xprt, xid);
296found:
297 spin_unlock(&xprt->bc_pa_lock);
298 return req;
299}
300
301/*
302 * Add callback request to callback list. The callback
303 * service sleeps on the sv_cb_waitq waiting for new
304 * requests. Wake it up after adding enqueing the
305 * request.
306 */
307void xprt_complete_bc_request(struct rpc_rqst *req, uint32_t copied)
308{
309 struct rpc_xprt *xprt = req->rq_xprt;
310 struct svc_serv *bc_serv = xprt->bc_serv;
311
312 req->rq_private_buf.len = copied;
313 set_bit(RPC_BC_PA_IN_USE, &req->rq_bc_pa_state);
314
315 dprintk("RPC: add callback request to list\n");
316 spin_lock(&bc_serv->sv_cb_lock);
317 list_del(&req->rq_bc_pa_list);
318 list_add(&req->rq_bc_list, &bc_serv->sv_cb_list);
319 wake_up(&bc_serv->sv_cb_waitq);
320 spin_unlock(&bc_serv->sv_cb_lock);
321}
322