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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); | |
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 | */ | |
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 | } | |
0d961aa9 | 177 | EXPORT_SYMBOL_GPL(xprt_setup_backchannel); |
fb7a0b9a RL |
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 | */ | |
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 | } | |
0d961aa9 | 207 | EXPORT_SYMBOL_GPL(xprt_destroy_backchannel); |
fb7a0b9a RL |
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 | * | |
e9f02985 RL |
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 | * | |
fb7a0b9a RL |
218 | * Return an available rpc_rqst, otherwise NULL if non are available. |
219 | */ | |
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"); | |
e9f02985 | 225 | spin_lock(&xprt->bc_pa_lock); |
fb7a0b9a RL |
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 | } | |
e9f02985 | 233 | spin_unlock(&xprt->bc_pa_lock); |
fb7a0b9a RL |
234 | |
235 | if (req != NULL) { | |
236 | set_bit(RPC_BC_PA_IN_USE, &req->rq_bc_pa_state); | |
dd2b63d0 | 237 | req->rq_reply_bytes_recvd = 0; |
fb7a0b9a RL |
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 | */ | |
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 |