1/****************************************************************************** 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> 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#ifdef RPC_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 */ 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); 62 WARN_ON_ONCE(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 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 */ 170 list_for_each_entry_safe(req, tmp, &tmp_list, rq_bc_pa_list) { 171 list_del(&req->rq_bc_pa_list); 172 xprt_free_allocation(req); 173 } 174 175 dprintk("RPC: setup backchannel transport failed\n"); 176 return -ENOMEM; 177} 178EXPORT_SYMBOL_GPL(xprt_setup_backchannel); 179 180/** 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 * 185 * 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. 188 */ 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"); 194 195 if (max_reqs == 0) 196 goto out; 197 198 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); 202 list_del(&req->rq_bc_pa_list); 203 xprt_free_allocation(req); 204 if (--max_reqs == 0) 205 break; 206 } 207 spin_unlock_bh(&xprt->bc_pa_lock); 208 209out: 210 dprintk("RPC: backchannel list empty= %s\n", 211 list_empty(&xprt->bc_pa_list) ? "true" : "false"); 212} 213EXPORT_SYMBOL_GPL(xprt_destroy_backchannel); 214 215static struct rpc_rqst *xprt_alloc_bc_request(struct rpc_xprt *xprt, __be32 xid) 216{ 217 struct rpc_rqst *req = NULL; 218 219 dprintk("RPC: allocate a backchannel request\n"); 220 if (list_empty(&xprt->bc_pa_list)) 221 goto not_found; 222 223 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, 228 sizeof(req->rq_private_buf)); 229 req->rq_xid = xid; 230 req->rq_connect_cookie = xprt->connect_cookie; 231not_found: 232 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); 245 246 req->rq_connect_cookie = xprt->connect_cookie - 1; 247 smp_mb__before_atomic(); 248 WARN_ON_ONCE(!test_bit(RPC_BC_PA_IN_USE, &req->rq_bc_pa_state)); 249 clear_bit(RPC_BC_PA_IN_USE, &req->rq_bc_pa_state); 250 smp_mb__after_atomic(); 251 252 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); 269 list_add_tail(&req->rq_bc_pa_list, &xprt->bc_pa_list); 270 spin_unlock_bh(&xprt->bc_pa_lock); 271} 272 273/* 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} 322 323