backchannel_rqst.c revision e9f029855865e917821ef6034b31e340a4cfc815
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/sunrpc/xprt.h> 26 27#ifdef RPC_DEBUG 28#define RPCDBG_FACILITY RPCDBG_TRANS 29#endif 30 31#if defined(CONFIG_NFS_V4_1) 32 33/* 34 * Helper routines that track the number of preallocation elements 35 * on the transport. 36 */ 37static inline int xprt_need_to_requeue(struct rpc_xprt *xprt) 38{ 39 return xprt->bc_alloc_count > 0; 40} 41 42static inline void xprt_inc_alloc_count(struct rpc_xprt *xprt, unsigned int n) 43{ 44 xprt->bc_alloc_count += n; 45} 46 47static inline int xprt_dec_alloc_count(struct rpc_xprt *xprt, unsigned int n) 48{ 49 return xprt->bc_alloc_count -= n; 50} 51 52/* 53 * Free the preallocated rpc_rqst structure and the memory 54 * buffers hanging off of it. 55 */ 56static void xprt_free_allocation(struct rpc_rqst *req) 57{ 58 struct xdr_buf *xbufp; 59 60 dprintk("RPC: free allocations for req= %p\n", req); 61 BUG_ON(test_bit(RPC_BC_PA_IN_USE, &req->rq_bc_pa_state)); 62 xbufp = &req->rq_private_buf; 63 free_page((unsigned long)xbufp->head[0].iov_base); 64 xbufp = &req->rq_snd_buf; 65 free_page((unsigned long)xbufp->head[0].iov_base); 66 list_del(&req->rq_bc_pa_list); 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 xprt_free_allocation(req); 172 173 dprintk("RPC: setup backchannel transport failed\n"); 174 return -1; 175} 176EXPORT_SYMBOL(xprt_setup_backchannel); 177 178/* 179 * Destroys the backchannel preallocated structures. 180 * Since these structures may have been allocated by multiple calls 181 * to xprt_setup_backchannel, we only destroy up to the maximum number 182 * of reqs specified by the caller. 183 * @xprt: the transport holding the preallocated strucures 184 * @max_reqs the maximum number of preallocated structures to destroy 185 */ 186void xprt_destroy_backchannel(struct rpc_xprt *xprt, unsigned int max_reqs) 187{ 188 struct rpc_rqst *req = NULL, *tmp = NULL; 189 190 dprintk("RPC: destroy backchannel transport\n"); 191 192 BUG_ON(max_reqs == 0); 193 spin_lock_bh(&xprt->bc_pa_lock); 194 xprt_dec_alloc_count(xprt, max_reqs); 195 list_for_each_entry_safe(req, tmp, &xprt->bc_pa_list, rq_bc_pa_list) { 196 dprintk("RPC: req=%p\n", req); 197 xprt_free_allocation(req); 198 if (--max_reqs == 0) 199 break; 200 } 201 spin_unlock_bh(&xprt->bc_pa_lock); 202 203 dprintk("RPC: backchannel list empty= %s\n", 204 list_empty(&xprt->bc_pa_list) ? "true" : "false"); 205} 206EXPORT_SYMBOL(xprt_destroy_backchannel); 207 208/* 209 * One or more rpc_rqst structure have been preallocated during the 210 * backchannel setup. Buffer space for the send and private XDR buffers 211 * has been preallocated as well. Use xprt_alloc_bc_request to allocate 212 * to this request. Use xprt_free_bc_request to return it. 213 * 214 * We know that we're called in soft interrupt context, grab the spin_lock 215 * since there is no need to grab the bottom half spin_lock. 216 * 217 * Return an available rpc_rqst, otherwise NULL if non are available. 218 */ 219struct rpc_rqst *xprt_alloc_bc_request(struct rpc_xprt *xprt) 220{ 221 struct rpc_rqst *req; 222 223 dprintk("RPC: allocate a backchannel request\n"); 224 spin_lock(&xprt->bc_pa_lock); 225 if (!list_empty(&xprt->bc_pa_list)) { 226 req = list_first_entry(&xprt->bc_pa_list, struct rpc_rqst, 227 rq_bc_pa_list); 228 list_del(&req->rq_bc_pa_list); 229 } else { 230 req = NULL; 231 } 232 spin_unlock(&xprt->bc_pa_lock); 233 234 if (req != NULL) { 235 set_bit(RPC_BC_PA_IN_USE, &req->rq_bc_pa_state); 236 req->rq_reply_bytes_recvd = 0; 237 req->rq_bytes_sent = 0; 238 memcpy(&req->rq_private_buf, &req->rq_rcv_buf, 239 sizeof(req->rq_private_buf)); 240 } 241 dprintk("RPC: backchannel req=%p\n", req); 242 return req; 243} 244 245/* 246 * Return the preallocated rpc_rqst structure and XDR buffers 247 * associated with this rpc_task. 248 */ 249void xprt_free_bc_request(struct rpc_rqst *req) 250{ 251 struct rpc_xprt *xprt = req->rq_xprt; 252 253 dprintk("RPC: free backchannel req=%p\n", req); 254 255 smp_mb__before_clear_bit(); 256 BUG_ON(!test_bit(RPC_BC_PA_IN_USE, &req->rq_bc_pa_state)); 257 clear_bit(RPC_BC_PA_IN_USE, &req->rq_bc_pa_state); 258 smp_mb__after_clear_bit(); 259 260 if (!xprt_need_to_requeue(xprt)) { 261 /* 262 * The last remaining session was destroyed while this 263 * entry was in use. Free the entry and don't attempt 264 * to add back to the list because there is no need to 265 * have anymore preallocated entries. 266 */ 267 dprintk("RPC: Last session removed req=%p\n", req); 268 xprt_free_allocation(req); 269 return; 270 } 271 272 /* 273 * Return it to the list of preallocations so that it 274 * may be reused by a new callback request. 275 */ 276 spin_lock_bh(&xprt->bc_pa_lock); 277 list_add(&req->rq_bc_pa_list, &xprt->bc_pa_list); 278 spin_unlock_bh(&xprt->bc_pa_lock); 279} 280 281#endif /* CONFIG_NFS_V4_1 */ 282