1 /******************************************************************************
3 (c) 2007 Network Appliance, Inc. All Rights Reserved.
4 (c) 2009 NetApp. All Rights Reserved.
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.
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.
22 ******************************************************************************/
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>
30 #if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
31 #define RPCDBG_FACILITY RPCDBG_TRANS
35 * Helper routines that track the number of preallocation elements
38 static inline int xprt_need_to_requeue(struct rpc_xprt *xprt)
40 return xprt->bc_alloc_count < atomic_read(&xprt->bc_free_slots);
43 static inline void xprt_inc_alloc_count(struct rpc_xprt *xprt, unsigned int n)
45 atomic_add(n, &xprt->bc_free_slots);
46 xprt->bc_alloc_count += n;
49 static inline int xprt_dec_alloc_count(struct rpc_xprt *xprt, unsigned int n)
51 atomic_sub(n, &xprt->bc_free_slots);
52 return xprt->bc_alloc_count -= n;
56 * Free the preallocated rpc_rqst structure and the memory
57 * buffers hanging off of it.
59 static void xprt_free_allocation(struct rpc_rqst *req)
61 struct xdr_buf *xbufp;
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);
72 static int xprt_alloc_xdr_buf(struct xdr_buf *buf, gfp_t gfp_flags)
75 /* Preallocate one XDR receive buffer */
76 page = alloc_page(gfp_flags);
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;
85 buf->buflen = PAGE_SIZE;
90 struct rpc_rqst *xprt_alloc_bc_req(struct rpc_xprt *xprt, gfp_t gfp_flags)
94 /* Pre-allocate one backchannel rpc_rqst */
95 req = kzalloc(sizeof(*req), gfp_flags);
100 INIT_LIST_HEAD(&req->rq_list);
101 INIT_LIST_HEAD(&req->rq_bc_list);
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");
108 req->rq_rcv_buf.len = PAGE_SIZE;
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");
117 xprt_free_allocation(req);
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
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.
139 int xprt_setup_backchannel(struct rpc_xprt *xprt, unsigned int min_reqs)
141 struct rpc_rqst *req;
142 struct list_head tmp_list;
145 dprintk("RPC: setup backchannel transport\n");
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.
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);
160 printk(KERN_ERR "Failed to create bc rpc_rqst\n");
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);
170 * Add the temporary list to the backchannel preallocation list
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);
177 dprintk("RPC: setup backchannel transport done\n");
182 * Memory allocation failed, free the temporary list
184 while (!list_empty(&tmp_list)) {
185 req = list_first_entry(&tmp_list,
188 list_del(&req->rq_bc_pa_list);
189 xprt_free_allocation(req);
192 dprintk("RPC: setup backchannel transport failed\n");
195 EXPORT_SYMBOL_GPL(xprt_setup_backchannel);
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
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.
206 void xprt_destroy_backchannel(struct rpc_xprt *xprt, unsigned int max_reqs)
208 struct rpc_rqst *req = NULL, *tmp = NULL;
210 dprintk("RPC: destroy backchannel transport\n");
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);
224 spin_unlock_bh(&xprt->bc_pa_lock);
227 dprintk("RPC: backchannel list empty= %s\n",
228 list_empty(&xprt->bc_pa_list) ? "true" : "false");
230 EXPORT_SYMBOL_GPL(xprt_destroy_backchannel);
232 static struct rpc_rqst *xprt_alloc_bc_request(struct rpc_xprt *xprt, __be32 xid)
234 struct rpc_rqst *req = NULL;
236 dprintk("RPC: allocate a backchannel request\n");
237 if (atomic_read(&xprt->bc_free_slots) <= 0)
239 if (list_empty(&xprt->bc_pa_list)) {
240 req = xprt_alloc_bc_req(xprt, GFP_ATOMIC);
243 list_add_tail(&req->rq_bc_pa_list, &xprt->bc_pa_list);
244 xprt->bc_alloc_count++;
246 req = list_first_entry(&xprt->bc_pa_list, struct rpc_rqst,
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));
253 req->rq_connect_cookie = xprt->connect_cookie;
255 dprintk("RPC: backchannel req=%p\n", req);
260 * Return the preallocated rpc_rqst structure and XDR buffers
261 * associated with this rpc_task.
263 void xprt_free_bc_request(struct rpc_rqst *req)
265 struct rpc_xprt *xprt = req->rq_xprt;
267 dprintk("RPC: free backchannel req=%p\n", req);
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();
275 * Return it to the list of preallocations so that it
276 * may be reused by a new callback request.
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++;
284 spin_unlock_bh(&xprt->bc_pa_lock);
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.
292 dprintk("RPC: Last session removed req=%p\n", req);
293 xprt_free_allocation(req);
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.
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.
307 * Return an available rpc_rqst, otherwise NULL if non are available.
309 struct rpc_rqst *xprt_lookup_bc_request(struct rpc_xprt *xprt, __be32 xid)
311 struct rpc_rqst *req;
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)
317 if (req->rq_xid == xid)
320 req = xprt_alloc_bc_request(xprt, xid);
322 spin_unlock(&xprt->bc_pa_lock);
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
332 void xprt_complete_bc_request(struct rpc_rqst *req, uint32_t copied)
334 struct rpc_xprt *xprt = req->rq_xprt;
335 struct svc_serv *bc_serv = xprt->bc_serv;
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);
342 req->rq_private_buf.len = copied;
343 set_bit(RPC_BC_PA_IN_USE, &req->rq_bc_pa_state);
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);