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 https://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 #define BC_MAX_SLOTS 64U 35 36 unsigned int xprt_bc_max_slots(struct rpc_xprt *xprt) 37 { 38 return BC_MAX_SLOTS; 39 } 40 41 /* 42 * Helper routines that track the number of preallocation elements 43 * on the transport. 44 */ 45 static inline int xprt_need_to_requeue(struct rpc_xprt *xprt) 46 { 47 return xprt->bc_alloc_count < xprt->bc_alloc_max; 48 } 49 50 /* 51 * Free the preallocated rpc_rqst structure and the memory 52 * buffers hanging off of it. 53 */ 54 static void xprt_free_allocation(struct rpc_rqst *req) 55 { 56 struct xdr_buf *xbufp; 57 58 dprintk("RPC: free allocations for req= %p\n", req); 59 WARN_ON_ONCE(test_bit(RPC_BC_PA_IN_USE, &req->rq_bc_pa_state)); 60 xbufp = &req->rq_rcv_buf; 61 free_page((unsigned long)xbufp->head[0].iov_base); 62 xbufp = &req->rq_snd_buf; 63 free_page((unsigned long)xbufp->head[0].iov_base); 64 kfree(req); 65 } 66 67 static void xprt_bc_reinit_xdr_buf(struct xdr_buf *buf) 68 { 69 buf->head[0].iov_len = PAGE_SIZE; 70 buf->tail[0].iov_len = 0; 71 buf->pages = NULL; 72 buf->page_len = 0; 73 buf->flags = 0; 74 buf->len = 0; 75 buf->buflen = PAGE_SIZE; 76 } 77 78 static int xprt_alloc_xdr_buf(struct xdr_buf *buf, gfp_t gfp_flags) 79 { 80 struct page *page; 81 /* Preallocate one XDR receive buffer */ 82 page = alloc_page(gfp_flags); 83 if (page == NULL) 84 return -ENOMEM; 85 xdr_buf_init(buf, page_address(page), PAGE_SIZE); 86 return 0; 87 } 88 89 static struct rpc_rqst *xprt_alloc_bc_req(struct rpc_xprt *xprt) 90 { 91 gfp_t gfp_flags = GFP_KERNEL | __GFP_NORETRY | __GFP_NOWARN; 92 struct rpc_rqst *req; 93 94 /* Pre-allocate one backchannel rpc_rqst */ 95 req = kzalloc(sizeof(*req), gfp_flags); 96 if (req == NULL) 97 return NULL; 98 99 req->rq_xprt = xprt; 100 INIT_LIST_HEAD(&req->rq_bc_list); 101 102 /* Preallocate one XDR receive buffer */ 103 if (xprt_alloc_xdr_buf(&req->rq_rcv_buf, gfp_flags) < 0) { 104 printk(KERN_ERR "Failed to create bc receive xbuf\n"); 105 goto out_free; 106 } 107 req->rq_rcv_buf.len = PAGE_SIZE; 108 109 /* Preallocate one XDR send buffer */ 110 if (xprt_alloc_xdr_buf(&req->rq_snd_buf, gfp_flags) < 0) { 111 printk(KERN_ERR "Failed to create bc snd xbuf\n"); 112 goto out_free; 113 } 114 return req; 115 out_free: 116 xprt_free_allocation(req); 117 return NULL; 118 } 119 120 /* 121 * Preallocate up to min_reqs structures and related buffers for use 122 * by the backchannel. This function can be called multiple times 123 * when creating new sessions that use the same rpc_xprt. The 124 * preallocated buffers are added to the pool of resources used by 125 * the rpc_xprt. Any one of these resources may be used by an 126 * incoming callback request. It's up to the higher levels in the 127 * stack to enforce that the maximum number of session slots is not 128 * being exceeded. 129 * 130 * Some callback arguments can be large. For example, a pNFS server 131 * using multiple deviceids. The list can be unbound, but the client 132 * has the ability to tell the server the maximum size of the callback 133 * requests. Each deviceID is 16 bytes, so allocate one page 134 * for the arguments to have enough room to receive a number of these 135 * deviceIDs. The NFS client indicates to the pNFS server that its 136 * callback requests can be up to 4096 bytes in size. 137 */ 138 int xprt_setup_backchannel(struct rpc_xprt *xprt, unsigned int min_reqs) 139 { 140 if (!xprt->ops->bc_setup) 141 return 0; 142 return xprt->ops->bc_setup(xprt, min_reqs); 143 } 144 EXPORT_SYMBOL_GPL(xprt_setup_backchannel); 145 146 int xprt_setup_bc(struct rpc_xprt *xprt, unsigned int min_reqs) 147 { 148 struct rpc_rqst *req; 149 struct list_head tmp_list; 150 int i; 151 152 dprintk("RPC: setup backchannel transport\n"); 153 154 if (min_reqs > BC_MAX_SLOTS) 155 min_reqs = BC_MAX_SLOTS; 156 157 /* 158 * We use a temporary list to keep track of the preallocated 159 * buffers. Once we're done building the list we splice it 160 * into the backchannel preallocation list off of the rpc_xprt 161 * struct. This helps minimize the amount of time the list 162 * lock is held on the rpc_xprt struct. It also makes cleanup 163 * easier in case of memory allocation errors. 164 */ 165 INIT_LIST_HEAD(&tmp_list); 166 for (i = 0; i < min_reqs; i++) { 167 /* Pre-allocate one backchannel rpc_rqst */ 168 req = xprt_alloc_bc_req(xprt); 169 if (req == NULL) { 170 printk(KERN_ERR "Failed to create bc rpc_rqst\n"); 171 goto out_free; 172 } 173 174 /* Add the allocated buffer to the tmp list */ 175 dprintk("RPC: adding req= %p\n", req); 176 list_add(&req->rq_bc_pa_list, &tmp_list); 177 } 178 179 /* 180 * Add the temporary list to the backchannel preallocation list 181 */ 182 spin_lock(&xprt->bc_pa_lock); 183 list_splice(&tmp_list, &xprt->bc_pa_list); 184 xprt->bc_alloc_count += min_reqs; 185 xprt->bc_alloc_max += min_reqs; 186 atomic_add(min_reqs, &xprt->bc_slot_count); 187 spin_unlock(&xprt->bc_pa_lock); 188 189 dprintk("RPC: setup backchannel transport done\n"); 190 return 0; 191 192 out_free: 193 /* 194 * Memory allocation failed, free the temporary list 195 */ 196 while (!list_empty(&tmp_list)) { 197 req = list_first_entry(&tmp_list, 198 struct rpc_rqst, 199 rq_bc_pa_list); 200 list_del(&req->rq_bc_pa_list); 201 xprt_free_allocation(req); 202 } 203 204 dprintk("RPC: setup backchannel transport failed\n"); 205 return -ENOMEM; 206 } 207 208 /** 209 * xprt_destroy_backchannel - Destroys the backchannel preallocated structures. 210 * @xprt: the transport holding the preallocated strucures 211 * @max_reqs: the maximum number of preallocated structures to destroy 212 * 213 * Since these structures may have been allocated by multiple calls 214 * to xprt_setup_backchannel, we only destroy up to the maximum number 215 * of reqs specified by the caller. 216 */ 217 void xprt_destroy_backchannel(struct rpc_xprt *xprt, unsigned int max_reqs) 218 { 219 if (xprt->ops->bc_destroy) 220 xprt->ops->bc_destroy(xprt, max_reqs); 221 } 222 EXPORT_SYMBOL_GPL(xprt_destroy_backchannel); 223 224 void xprt_destroy_bc(struct rpc_xprt *xprt, unsigned int max_reqs) 225 { 226 struct rpc_rqst *req = NULL, *tmp = NULL; 227 228 dprintk("RPC: destroy backchannel transport\n"); 229 230 if (max_reqs == 0) 231 goto out; 232 233 spin_lock_bh(&xprt->bc_pa_lock); 234 xprt->bc_alloc_max -= min(max_reqs, xprt->bc_alloc_max); 235 list_for_each_entry_safe(req, tmp, &xprt->bc_pa_list, rq_bc_pa_list) { 236 dprintk("RPC: req=%p\n", req); 237 list_del(&req->rq_bc_pa_list); 238 xprt_free_allocation(req); 239 xprt->bc_alloc_count--; 240 atomic_dec(&xprt->bc_slot_count); 241 if (--max_reqs == 0) 242 break; 243 } 244 spin_unlock_bh(&xprt->bc_pa_lock); 245 246 out: 247 dprintk("RPC: backchannel list empty= %s\n", 248 list_empty(&xprt->bc_pa_list) ? "true" : "false"); 249 } 250 251 static struct rpc_rqst *xprt_get_bc_request(struct rpc_xprt *xprt, __be32 xid, 252 struct rpc_rqst *new) 253 { 254 struct rpc_rqst *req = NULL; 255 256 dprintk("RPC: allocate a backchannel request\n"); 257 if (list_empty(&xprt->bc_pa_list)) { 258 if (!new) 259 goto not_found; 260 if (atomic_read(&xprt->bc_slot_count) >= BC_MAX_SLOTS) 261 goto not_found; 262 list_add_tail(&new->rq_bc_pa_list, &xprt->bc_pa_list); 263 xprt->bc_alloc_count++; 264 atomic_inc(&xprt->bc_slot_count); 265 } 266 req = list_first_entry(&xprt->bc_pa_list, struct rpc_rqst, 267 rq_bc_pa_list); 268 req->rq_reply_bytes_recvd = 0; 269 memcpy(&req->rq_private_buf, &req->rq_rcv_buf, 270 sizeof(req->rq_private_buf)); 271 req->rq_xid = xid; 272 req->rq_connect_cookie = xprt->connect_cookie; 273 dprintk("RPC: backchannel req=%p\n", req); 274 not_found: 275 return req; 276 } 277 278 /* 279 * Return the preallocated rpc_rqst structure and XDR buffers 280 * associated with this rpc_task. 281 */ 282 void xprt_free_bc_request(struct rpc_rqst *req) 283 { 284 struct rpc_xprt *xprt = req->rq_xprt; 285 286 xprt->ops->bc_free_rqst(req); 287 } 288 289 void xprt_free_bc_rqst(struct rpc_rqst *req) 290 { 291 struct rpc_xprt *xprt = req->rq_xprt; 292 293 dprintk("RPC: free backchannel req=%p\n", req); 294 295 req->rq_connect_cookie = xprt->connect_cookie - 1; 296 smp_mb__before_atomic(); 297 clear_bit(RPC_BC_PA_IN_USE, &req->rq_bc_pa_state); 298 smp_mb__after_atomic(); 299 300 /* 301 * Return it to the list of preallocations so that it 302 * may be reused by a new callback request. 303 */ 304 spin_lock_bh(&xprt->bc_pa_lock); 305 if (xprt_need_to_requeue(xprt)) { 306 xprt_bc_reinit_xdr_buf(&req->rq_snd_buf); 307 xprt_bc_reinit_xdr_buf(&req->rq_rcv_buf); 308 req->rq_rcv_buf.len = PAGE_SIZE; 309 list_add_tail(&req->rq_bc_pa_list, &xprt->bc_pa_list); 310 xprt->bc_alloc_count++; 311 atomic_inc(&xprt->bc_slot_count); 312 req = NULL; 313 } 314 spin_unlock_bh(&xprt->bc_pa_lock); 315 if (req != NULL) { 316 /* 317 * The last remaining session was destroyed while this 318 * entry was in use. Free the entry and don't attempt 319 * to add back to the list because there is no need to 320 * have anymore preallocated entries. 321 */ 322 dprintk("RPC: Last session removed req=%p\n", req); 323 xprt_free_allocation(req); 324 } 325 xprt_put(xprt); 326 } 327 328 /* 329 * One or more rpc_rqst structure have been preallocated during the 330 * backchannel setup. Buffer space for the send and private XDR buffers 331 * has been preallocated as well. Use xprt_alloc_bc_request to allocate 332 * to this request. Use xprt_free_bc_request to return it. 333 * 334 * We know that we're called in soft interrupt context, grab the spin_lock 335 * since there is no need to grab the bottom half spin_lock. 336 * 337 * Return an available rpc_rqst, otherwise NULL if non are available. 338 */ 339 struct rpc_rqst *xprt_lookup_bc_request(struct rpc_xprt *xprt, __be32 xid) 340 { 341 struct rpc_rqst *req, *new = NULL; 342 343 do { 344 spin_lock(&xprt->bc_pa_lock); 345 list_for_each_entry(req, &xprt->bc_pa_list, rq_bc_pa_list) { 346 if (req->rq_connect_cookie != xprt->connect_cookie) 347 continue; 348 if (req->rq_xid == xid) 349 goto found; 350 } 351 req = xprt_get_bc_request(xprt, xid, new); 352 found: 353 spin_unlock(&xprt->bc_pa_lock); 354 if (new) { 355 if (req != new) 356 xprt_free_allocation(new); 357 break; 358 } else if (req) 359 break; 360 new = xprt_alloc_bc_req(xprt); 361 } while (new); 362 return req; 363 } 364 365 /* 366 * Add callback request to callback list. The callback 367 * service sleeps on the sv_cb_waitq waiting for new 368 * requests. Wake it up after adding enqueing the 369 * request. 370 */ 371 void xprt_complete_bc_request(struct rpc_rqst *req, uint32_t copied) 372 { 373 struct rpc_xprt *xprt = req->rq_xprt; 374 struct svc_serv *bc_serv = xprt->bc_serv; 375 376 spin_lock(&xprt->bc_pa_lock); 377 list_del(&req->rq_bc_pa_list); 378 xprt->bc_alloc_count--; 379 spin_unlock(&xprt->bc_pa_lock); 380 381 req->rq_private_buf.len = copied; 382 set_bit(RPC_BC_PA_IN_USE, &req->rq_bc_pa_state); 383 384 dprintk("RPC: add callback request to list\n"); 385 xprt_get(xprt); 386 spin_lock(&bc_serv->sv_cb_lock); 387 list_add(&req->rq_bc_list, &bc_serv->sv_cb_list); 388 wake_up(&bc_serv->sv_cb_waitq); 389 spin_unlock(&bc_serv->sv_cb_lock); 390 } 391