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