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 #if IS_ENABLED(CONFIG_SUNRPC_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 */ 38 static inline int xprt_need_to_requeue(struct rpc_xprt *xprt) 39 { 40 return xprt->bc_alloc_count < atomic_read(&xprt->bc_free_slots); 41 } 42 43 static inline void xprt_inc_alloc_count(struct rpc_xprt *xprt, unsigned int n) 44 { 45 atomic_add(n, &xprt->bc_free_slots); 46 xprt->bc_alloc_count += n; 47 } 48 49 static inline int xprt_dec_alloc_count(struct rpc_xprt *xprt, unsigned int n) 50 { 51 atomic_sub(n, &xprt->bc_free_slots); 52 return xprt->bc_alloc_count -= n; 53 } 54 55 /* 56 * Free the preallocated rpc_rqst structure and the memory 57 * buffers hanging off of it. 58 */ 59 static void xprt_free_allocation(struct rpc_rqst *req) 60 { 61 struct xdr_buf *xbufp; 62 63 dprintk("RPC: free allocations for req= %p\n", req); 64 WARN_ON_ONCE(test_bit(RPC_BC_PA_IN_USE, &req->rq_bc_pa_state)); 65 xbufp = &req->rq_rcv_buf; 66 free_page((unsigned long)xbufp->head[0].iov_base); 67 xbufp = &req->rq_snd_buf; 68 free_page((unsigned long)xbufp->head[0].iov_base); 69 kfree(req); 70 } 71 72 static int xprt_alloc_xdr_buf(struct xdr_buf *buf, gfp_t gfp_flags) 73 { 74 struct page *page; 75 /* Preallocate one XDR receive buffer */ 76 page = alloc_page(gfp_flags); 77 if (page == NULL) 78 return -ENOMEM; 79 xdr_buf_init(buf, page_address(page), PAGE_SIZE); 80 return 0; 81 } 82 83 static 84 struct rpc_rqst *xprt_alloc_bc_req(struct rpc_xprt *xprt, gfp_t gfp_flags) 85 { 86 struct rpc_rqst *req; 87 88 /* Pre-allocate one backchannel rpc_rqst */ 89 req = kzalloc(sizeof(*req), gfp_flags); 90 if (req == NULL) 91 return NULL; 92 93 req->rq_xprt = xprt; 94 INIT_LIST_HEAD(&req->rq_list); 95 INIT_LIST_HEAD(&req->rq_bc_list); 96 97 /* Preallocate one XDR receive buffer */ 98 if (xprt_alloc_xdr_buf(&req->rq_rcv_buf, gfp_flags) < 0) { 99 printk(KERN_ERR "Failed to create bc receive xbuf\n"); 100 goto out_free; 101 } 102 req->rq_rcv_buf.len = PAGE_SIZE; 103 104 /* Preallocate one XDR send buffer */ 105 if (xprt_alloc_xdr_buf(&req->rq_snd_buf, gfp_flags) < 0) { 106 printk(KERN_ERR "Failed to create bc snd xbuf\n"); 107 goto out_free; 108 } 109 return req; 110 out_free: 111 xprt_free_allocation(req); 112 return NULL; 113 } 114 115 /* 116 * Preallocate up to min_reqs structures and related buffers for use 117 * by the backchannel. This function can be called multiple times 118 * when creating new sessions that use the same rpc_xprt. The 119 * preallocated buffers are added to the pool of resources used by 120 * the rpc_xprt. Anyone of these resources may be used used by an 121 * incoming callback request. It's up to the higher levels in the 122 * stack to enforce that the maximum number of session slots is not 123 * being exceeded. 124 * 125 * Some callback arguments can be large. For example, a pNFS server 126 * using multiple deviceids. The list can be unbound, but the client 127 * has the ability to tell the server the maximum size of the callback 128 * requests. Each deviceID is 16 bytes, so allocate one page 129 * for the arguments to have enough room to receive a number of these 130 * deviceIDs. The NFS client indicates to the pNFS server that its 131 * callback requests can be up to 4096 bytes in size. 132 */ 133 int xprt_setup_backchannel(struct rpc_xprt *xprt, unsigned int min_reqs) 134 { 135 if (!xprt->ops->bc_setup) 136 return 0; 137 return xprt->ops->bc_setup(xprt, min_reqs); 138 } 139 EXPORT_SYMBOL_GPL(xprt_setup_backchannel); 140 141 int xprt_setup_bc(struct rpc_xprt *xprt, unsigned int min_reqs) 142 { 143 struct rpc_rqst *req; 144 struct list_head tmp_list; 145 int i; 146 147 dprintk("RPC: setup backchannel transport\n"); 148 149 /* 150 * We use a temporary list to keep track of the preallocated 151 * buffers. Once we're done building the list we splice it 152 * into the backchannel preallocation list off of the rpc_xprt 153 * struct. This helps minimize the amount of time the list 154 * lock is held on the rpc_xprt struct. It also makes cleanup 155 * easier in case of memory allocation errors. 156 */ 157 INIT_LIST_HEAD(&tmp_list); 158 for (i = 0; i < min_reqs; i++) { 159 /* Pre-allocate one backchannel rpc_rqst */ 160 req = xprt_alloc_bc_req(xprt, GFP_KERNEL); 161 if (req == NULL) { 162 printk(KERN_ERR "Failed to create bc rpc_rqst\n"); 163 goto out_free; 164 } 165 166 /* Add the allocated buffer to the tmp list */ 167 dprintk("RPC: adding req= %p\n", req); 168 list_add(&req->rq_bc_pa_list, &tmp_list); 169 } 170 171 /* 172 * Add the temporary list to the backchannel preallocation list 173 */ 174 spin_lock(&xprt->bc_pa_lock); 175 list_splice(&tmp_list, &xprt->bc_pa_list); 176 xprt_inc_alloc_count(xprt, min_reqs); 177 spin_unlock(&xprt->bc_pa_lock); 178 179 dprintk("RPC: setup backchannel transport done\n"); 180 return 0; 181 182 out_free: 183 /* 184 * Memory allocation failed, free the temporary list 185 */ 186 while (!list_empty(&tmp_list)) { 187 req = list_first_entry(&tmp_list, 188 struct rpc_rqst, 189 rq_bc_pa_list); 190 list_del(&req->rq_bc_pa_list); 191 xprt_free_allocation(req); 192 } 193 194 dprintk("RPC: setup backchannel transport failed\n"); 195 return -ENOMEM; 196 } 197 198 /** 199 * xprt_destroy_backchannel - Destroys the backchannel preallocated structures. 200 * @xprt: the transport holding the preallocated strucures 201 * @max_reqs the maximum number of preallocated structures to destroy 202 * 203 * Since these structures may have been allocated by multiple calls 204 * to xprt_setup_backchannel, we only destroy up to the maximum number 205 * of reqs specified by the caller. 206 */ 207 void xprt_destroy_backchannel(struct rpc_xprt *xprt, unsigned int max_reqs) 208 { 209 if (xprt->ops->bc_destroy) 210 xprt->ops->bc_destroy(xprt, max_reqs); 211 } 212 EXPORT_SYMBOL_GPL(xprt_destroy_backchannel); 213 214 void xprt_destroy_bc(struct rpc_xprt *xprt, unsigned int max_reqs) 215 { 216 struct rpc_rqst *req = NULL, *tmp = NULL; 217 218 dprintk("RPC: destroy backchannel transport\n"); 219 220 if (max_reqs == 0) 221 goto out; 222 223 spin_lock_bh(&xprt->bc_pa_lock); 224 xprt_dec_alloc_count(xprt, max_reqs); 225 list_for_each_entry_safe(req, tmp, &xprt->bc_pa_list, rq_bc_pa_list) { 226 dprintk("RPC: req=%p\n", req); 227 list_del(&req->rq_bc_pa_list); 228 xprt_free_allocation(req); 229 if (--max_reqs == 0) 230 break; 231 } 232 spin_unlock_bh(&xprt->bc_pa_lock); 233 234 out: 235 dprintk("RPC: backchannel list empty= %s\n", 236 list_empty(&xprt->bc_pa_list) ? "true" : "false"); 237 } 238 239 static struct rpc_rqst *xprt_alloc_bc_request(struct rpc_xprt *xprt, __be32 xid) 240 { 241 struct rpc_rqst *req = NULL; 242 243 dprintk("RPC: allocate a backchannel request\n"); 244 if (atomic_read(&xprt->bc_free_slots) <= 0) 245 goto not_found; 246 if (list_empty(&xprt->bc_pa_list)) { 247 req = xprt_alloc_bc_req(xprt, GFP_ATOMIC); 248 if (!req) 249 goto not_found; 250 list_add_tail(&req->rq_bc_pa_list, &xprt->bc_pa_list); 251 xprt->bc_alloc_count++; 252 } 253 req = list_first_entry(&xprt->bc_pa_list, struct rpc_rqst, 254 rq_bc_pa_list); 255 req->rq_reply_bytes_recvd = 0; 256 req->rq_bytes_sent = 0; 257 memcpy(&req->rq_private_buf, &req->rq_rcv_buf, 258 sizeof(req->rq_private_buf)); 259 req->rq_xid = xid; 260 req->rq_connect_cookie = xprt->connect_cookie; 261 not_found: 262 dprintk("RPC: backchannel req=%p\n", req); 263 return req; 264 } 265 266 /* 267 * Return the preallocated rpc_rqst structure and XDR buffers 268 * associated with this rpc_task. 269 */ 270 void xprt_free_bc_request(struct rpc_rqst *req) 271 { 272 struct rpc_xprt *xprt = req->rq_xprt; 273 274 xprt->ops->bc_free_rqst(req); 275 } 276 277 void xprt_free_bc_rqst(struct rpc_rqst *req) 278 { 279 struct rpc_xprt *xprt = req->rq_xprt; 280 281 dprintk("RPC: free backchannel req=%p\n", req); 282 283 req->rq_connect_cookie = xprt->connect_cookie - 1; 284 smp_mb__before_atomic(); 285 clear_bit(RPC_BC_PA_IN_USE, &req->rq_bc_pa_state); 286 smp_mb__after_atomic(); 287 288 /* 289 * Return it to the list of preallocations so that it 290 * may be reused by a new callback request. 291 */ 292 spin_lock_bh(&xprt->bc_pa_lock); 293 if (xprt_need_to_requeue(xprt)) { 294 list_add_tail(&req->rq_bc_pa_list, &xprt->bc_pa_list); 295 xprt->bc_alloc_count++; 296 req = NULL; 297 } 298 spin_unlock_bh(&xprt->bc_pa_lock); 299 if (req != NULL) { 300 /* 301 * The last remaining session was destroyed while this 302 * entry was in use. Free the entry and don't attempt 303 * to add back to the list because there is no need to 304 * have anymore preallocated entries. 305 */ 306 dprintk("RPC: Last session removed req=%p\n", req); 307 xprt_free_allocation(req); 308 return; 309 } 310 } 311 312 /* 313 * One or more rpc_rqst structure have been preallocated during the 314 * backchannel setup. Buffer space for the send and private XDR buffers 315 * has been preallocated as well. Use xprt_alloc_bc_request to allocate 316 * to this request. Use xprt_free_bc_request to return it. 317 * 318 * We know that we're called in soft interrupt context, grab the spin_lock 319 * since there is no need to grab the bottom half spin_lock. 320 * 321 * Return an available rpc_rqst, otherwise NULL if non are available. 322 */ 323 struct rpc_rqst *xprt_lookup_bc_request(struct rpc_xprt *xprt, __be32 xid) 324 { 325 struct rpc_rqst *req; 326 327 spin_lock(&xprt->bc_pa_lock); 328 list_for_each_entry(req, &xprt->bc_pa_list, rq_bc_pa_list) { 329 if (req->rq_connect_cookie != xprt->connect_cookie) 330 continue; 331 if (req->rq_xid == xid) 332 goto found; 333 } 334 req = xprt_alloc_bc_request(xprt, xid); 335 found: 336 spin_unlock(&xprt->bc_pa_lock); 337 return req; 338 } 339 340 /* 341 * Add callback request to callback list. The callback 342 * service sleeps on the sv_cb_waitq waiting for new 343 * requests. Wake it up after adding enqueing the 344 * request. 345 */ 346 void xprt_complete_bc_request(struct rpc_rqst *req, uint32_t copied) 347 { 348 struct rpc_xprt *xprt = req->rq_xprt; 349 struct svc_serv *bc_serv = xprt->bc_serv; 350 351 spin_lock(&xprt->bc_pa_lock); 352 list_del(&req->rq_bc_pa_list); 353 xprt_dec_alloc_count(xprt, 1); 354 spin_unlock(&xprt->bc_pa_lock); 355 356 req->rq_private_buf.len = copied; 357 set_bit(RPC_BC_PA_IN_USE, &req->rq_bc_pa_state); 358 359 dprintk("RPC: add callback request to list\n"); 360 spin_lock(&bc_serv->sv_cb_lock); 361 list_add(&req->rq_bc_list, &bc_serv->sv_cb_list); 362 wake_up(&bc_serv->sv_cb_waitq); 363 spin_unlock(&bc_serv->sv_cb_lock); 364 } 365 366