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 28 #ifdef RPC_DEBUG 29 #define RPCDBG_FACILITY RPCDBG_TRANS 30 #endif 31 32 #if defined(CONFIG_NFS_V4_1) 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 > 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 } 177 EXPORT_SYMBOL(xprt_setup_backchannel); 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 } 207 EXPORT_SYMBOL(xprt_destroy_backchannel); 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 * 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 * 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"); 225 spin_lock(&xprt->bc_pa_lock); 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 } 233 spin_unlock(&xprt->bc_pa_lock); 234 235 if (req != NULL) { 236 set_bit(RPC_BC_PA_IN_USE, &req->rq_bc_pa_state); 237 req->rq_reply_bytes_recvd = 0; 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 } 281 282 #endif /* CONFIG_NFS_V4_1 */ 283