1 /* 2 drbd_req.h 3 4 This file is part of DRBD by Philipp Reisner and Lars Ellenberg. 5 6 Copyright (C) 2006-2008, LINBIT Information Technologies GmbH. 7 Copyright (C) 2006-2008, Lars Ellenberg <lars.ellenberg@linbit.com>. 8 Copyright (C) 2006-2008, Philipp Reisner <philipp.reisner@linbit.com>. 9 10 DRBD is free software; you can redistribute it and/or modify 11 it under the terms of the GNU General Public License as published by 12 the Free Software Foundation; either version 2, or (at your option) 13 any later version. 14 15 DRBD is distributed in the hope that it will be useful, 16 but WITHOUT ANY WARRANTY; without even the implied warranty of 17 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 18 GNU General Public License for more details. 19 20 You should have received a copy of the GNU General Public License 21 along with drbd; see the file COPYING. If not, write to 22 the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. 23 */ 24 25 #ifndef _DRBD_REQ_H 26 #define _DRBD_REQ_H 27 28 #include <linux/module.h> 29 30 #include <linux/slab.h> 31 #include <linux/drbd.h> 32 #include "drbd_int.h" 33 #include "drbd_wrappers.h" 34 35 /* The request callbacks will be called in irq context by the IDE drivers, 36 and in Softirqs/Tasklets/BH context by the SCSI drivers, 37 and by the receiver and worker in kernel-thread context. 38 Try to get the locking right :) */ 39 40 /* 41 * Objects of type struct drbd_request do only exist on a R_PRIMARY node, and are 42 * associated with IO requests originating from the block layer above us. 43 * 44 * There are quite a few things that may happen to a drbd request 45 * during its lifetime. 46 * 47 * It will be created. 48 * It will be marked with the intention to be 49 * submitted to local disk and/or 50 * send via the network. 51 * 52 * It has to be placed on the transfer log and other housekeeping lists, 53 * In case we have a network connection. 54 * 55 * It may be identified as a concurrent (write) request 56 * and be handled accordingly. 57 * 58 * It may me handed over to the local disk subsystem. 59 * It may be completed by the local disk subsystem, 60 * either successfully or with io-error. 61 * In case it is a READ request, and it failed locally, 62 * it may be retried remotely. 63 * 64 * It may be queued for sending. 65 * It may be handed over to the network stack, 66 * which may fail. 67 * It may be acknowledged by the "peer" according to the wire_protocol in use. 68 * this may be a negative ack. 69 * It may receive a faked ack when the network connection is lost and the 70 * transfer log is cleaned up. 71 * Sending may be canceled due to network connection loss. 72 * When it finally has outlived its time, 73 * corresponding dirty bits in the resync-bitmap may be cleared or set, 74 * it will be destroyed, 75 * and completion will be signalled to the originator, 76 * with or without "success". 77 */ 78 79 enum drbd_req_event { 80 created, 81 to_be_send, 82 to_be_submitted, 83 84 /* XXX yes, now I am inconsistent... 85 * these two are not "events" but "actions" 86 * oh, well... */ 87 queue_for_net_write, 88 queue_for_net_read, 89 90 send_canceled, 91 send_failed, 92 handed_over_to_network, 93 connection_lost_while_pending, 94 read_retry_remote_canceled, 95 recv_acked_by_peer, 96 write_acked_by_peer, 97 write_acked_by_peer_and_sis, /* and set_in_sync */ 98 conflict_discarded_by_peer, 99 neg_acked, 100 barrier_acked, /* in protocol A and B */ 101 data_received, /* (remote read) */ 102 103 read_completed_with_error, 104 read_ahead_completed_with_error, 105 write_completed_with_error, 106 completed_ok, 107 nothing, /* for tracing only */ 108 }; 109 110 /* encoding of request states for now. we don't actually need that many bits. 111 * we don't need to do atomic bit operations either, since most of the time we 112 * need to look at the connection state and/or manipulate some lists at the 113 * same time, so we should hold the request lock anyways. 114 */ 115 enum drbd_req_state_bits { 116 /* 210 117 * 000: no local possible 118 * 001: to be submitted 119 * UNUSED, we could map: 011: submitted, completion still pending 120 * 110: completed ok 121 * 010: completed with error 122 */ 123 __RQ_LOCAL_PENDING, 124 __RQ_LOCAL_COMPLETED, 125 __RQ_LOCAL_OK, 126 127 /* 76543 128 * 00000: no network possible 129 * 00001: to be send 130 * 00011: to be send, on worker queue 131 * 00101: sent, expecting recv_ack (B) or write_ack (C) 132 * 11101: sent, 133 * recv_ack (B) or implicit "ack" (A), 134 * still waiting for the barrier ack. 135 * master_bio may already be completed and invalidated. 136 * 11100: write_acked (C), 137 * data_received (for remote read, any protocol) 138 * or finally the barrier ack has arrived (B,A)... 139 * request can be freed 140 * 01100: neg-acked (write, protocol C) 141 * or neg-d-acked (read, any protocol) 142 * or killed from the transfer log 143 * during cleanup after connection loss 144 * request can be freed 145 * 01000: canceled or send failed... 146 * request can be freed 147 */ 148 149 /* if "SENT" is not set, yet, this can still fail or be canceled. 150 * if "SENT" is set already, we still wait for an Ack packet. 151 * when cleared, the master_bio may be completed. 152 * in (B,A) the request object may still linger on the transaction log 153 * until the corresponding barrier ack comes in */ 154 __RQ_NET_PENDING, 155 156 /* If it is QUEUED, and it is a WRITE, it is also registered in the 157 * transfer log. Currently we need this flag to avoid conflicts between 158 * worker canceling the request and tl_clear_barrier killing it from 159 * transfer log. We should restructure the code so this conflict does 160 * no longer occur. */ 161 __RQ_NET_QUEUED, 162 163 /* well, actually only "handed over to the network stack". 164 * 165 * TODO can potentially be dropped because of the similar meaning 166 * of RQ_NET_SENT and ~RQ_NET_QUEUED. 167 * however it is not exactly the same. before we drop it 168 * we must ensure that we can tell a request with network part 169 * from a request without, regardless of what happens to it. */ 170 __RQ_NET_SENT, 171 172 /* when set, the request may be freed (if RQ_NET_QUEUED is clear). 173 * basically this means the corresponding P_BARRIER_ACK was received */ 174 __RQ_NET_DONE, 175 176 /* whether or not we know (C) or pretend (B,A) that the write 177 * was successfully written on the peer. 178 */ 179 __RQ_NET_OK, 180 181 /* peer called drbd_set_in_sync() for this write */ 182 __RQ_NET_SIS, 183 184 /* keep this last, its for the RQ_NET_MASK */ 185 __RQ_NET_MAX, 186 }; 187 188 #define RQ_LOCAL_PENDING (1UL << __RQ_LOCAL_PENDING) 189 #define RQ_LOCAL_COMPLETED (1UL << __RQ_LOCAL_COMPLETED) 190 #define RQ_LOCAL_OK (1UL << __RQ_LOCAL_OK) 191 192 #define RQ_LOCAL_MASK ((RQ_LOCAL_OK << 1)-1) /* 0x07 */ 193 194 #define RQ_NET_PENDING (1UL << __RQ_NET_PENDING) 195 #define RQ_NET_QUEUED (1UL << __RQ_NET_QUEUED) 196 #define RQ_NET_SENT (1UL << __RQ_NET_SENT) 197 #define RQ_NET_DONE (1UL << __RQ_NET_DONE) 198 #define RQ_NET_OK (1UL << __RQ_NET_OK) 199 #define RQ_NET_SIS (1UL << __RQ_NET_SIS) 200 201 /* 0x1f8 */ 202 #define RQ_NET_MASK (((1UL << __RQ_NET_MAX)-1) & ~RQ_LOCAL_MASK) 203 204 /* epoch entries */ 205 static inline 206 struct hlist_head *ee_hash_slot(struct drbd_conf *mdev, sector_t sector) 207 { 208 BUG_ON(mdev->ee_hash_s == 0); 209 return mdev->ee_hash + 210 ((unsigned int)(sector>>HT_SHIFT) % mdev->ee_hash_s); 211 } 212 213 /* transfer log (drbd_request objects) */ 214 static inline 215 struct hlist_head *tl_hash_slot(struct drbd_conf *mdev, sector_t sector) 216 { 217 BUG_ON(mdev->tl_hash_s == 0); 218 return mdev->tl_hash + 219 ((unsigned int)(sector>>HT_SHIFT) % mdev->tl_hash_s); 220 } 221 222 /* application reads (drbd_request objects) */ 223 static struct hlist_head *ar_hash_slot(struct drbd_conf *mdev, sector_t sector) 224 { 225 return mdev->app_reads_hash 226 + ((unsigned int)(sector) % APP_R_HSIZE); 227 } 228 229 /* when we receive the answer for a read request, 230 * verify that we actually know about it */ 231 static inline struct drbd_request *_ar_id_to_req(struct drbd_conf *mdev, 232 u64 id, sector_t sector) 233 { 234 struct hlist_head *slot = ar_hash_slot(mdev, sector); 235 struct hlist_node *n; 236 struct drbd_request *req; 237 238 hlist_for_each_entry(req, n, slot, colision) { 239 if ((unsigned long)req == (unsigned long)id) { 240 D_ASSERT(req->sector == sector); 241 return req; 242 } 243 } 244 return NULL; 245 } 246 247 static inline struct drbd_request *drbd_req_new(struct drbd_conf *mdev, 248 struct bio *bio_src) 249 { 250 struct bio *bio; 251 struct drbd_request *req = 252 mempool_alloc(drbd_request_mempool, GFP_NOIO); 253 if (likely(req)) { 254 bio = bio_clone(bio_src, GFP_NOIO); /* XXX cannot fail?? */ 255 256 req->rq_state = 0; 257 req->mdev = mdev; 258 req->master_bio = bio_src; 259 req->private_bio = bio; 260 req->epoch = 0; 261 req->sector = bio->bi_sector; 262 req->size = bio->bi_size; 263 req->start_time = jiffies; 264 INIT_HLIST_NODE(&req->colision); 265 INIT_LIST_HEAD(&req->tl_requests); 266 INIT_LIST_HEAD(&req->w.list); 267 268 bio->bi_private = req; 269 bio->bi_end_io = drbd_endio_pri; 270 bio->bi_next = NULL; 271 } 272 return req; 273 } 274 275 static inline void drbd_req_free(struct drbd_request *req) 276 { 277 mempool_free(req, drbd_request_mempool); 278 } 279 280 static inline int overlaps(sector_t s1, int l1, sector_t s2, int l2) 281 { 282 return !((s1 + (l1>>9) <= s2) || (s1 >= s2 + (l2>>9))); 283 } 284 285 /* Short lived temporary struct on the stack. 286 * We could squirrel the error to be returned into 287 * bio->bi_size, or similar. But that would be too ugly. */ 288 struct bio_and_error { 289 struct bio *bio; 290 int error; 291 }; 292 293 extern void _req_may_be_done(struct drbd_request *req, 294 struct bio_and_error *m); 295 extern void __req_mod(struct drbd_request *req, enum drbd_req_event what, 296 struct bio_and_error *m); 297 extern void complete_master_bio(struct drbd_conf *mdev, 298 struct bio_and_error *m); 299 300 /* use this if you don't want to deal with calling complete_master_bio() 301 * outside the spinlock, e.g. when walking some list on cleanup. */ 302 static inline void _req_mod(struct drbd_request *req, enum drbd_req_event what) 303 { 304 struct drbd_conf *mdev = req->mdev; 305 struct bio_and_error m; 306 307 /* __req_mod possibly frees req, do not touch req after that! */ 308 __req_mod(req, what, &m); 309 if (m.bio) 310 complete_master_bio(mdev, &m); 311 } 312 313 /* completion of master bio is outside of spinlock. 314 * If you need it irqsave, do it your self! */ 315 static inline void req_mod(struct drbd_request *req, 316 enum drbd_req_event what) 317 { 318 struct drbd_conf *mdev = req->mdev; 319 struct bio_and_error m; 320 spin_lock_irq(&mdev->req_lock); 321 __req_mod(req, what, &m); 322 spin_unlock_irq(&mdev->req_lock); 323 324 if (m.bio) 325 complete_master_bio(mdev, &m); 326 } 327 #endif 328