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 are not "events" but "actions" 86 * oh, well... */ 87 queue_for_net_write, 88 queue_for_net_read, 89 queue_for_send_oos, 90 91 send_canceled, 92 send_failed, 93 handed_over_to_network, 94 oos_handed_to_network, 95 connection_lost_while_pending, 96 read_retry_remote_canceled, 97 recv_acked_by_peer, 98 write_acked_by_peer, 99 write_acked_by_peer_and_sis, /* and set_in_sync */ 100 conflict_discarded_by_peer, 101 neg_acked, 102 barrier_acked, /* in protocol A and B */ 103 data_received, /* (remote read) */ 104 105 read_completed_with_error, 106 read_ahead_completed_with_error, 107 write_completed_with_error, 108 completed_ok, 109 resend, 110 fail_frozen_disk_io, 111 restart_frozen_disk_io, 112 nothing, /* for tracing only */ 113 }; 114 115 /* encoding of request states for now. we don't actually need that many bits. 116 * we don't need to do atomic bit operations either, since most of the time we 117 * need to look at the connection state and/or manipulate some lists at the 118 * same time, so we should hold the request lock anyways. 119 */ 120 enum drbd_req_state_bits { 121 /* 210 122 * 000: no local possible 123 * 001: to be submitted 124 * UNUSED, we could map: 011: submitted, completion still pending 125 * 110: completed ok 126 * 010: completed with error 127 */ 128 __RQ_LOCAL_PENDING, 129 __RQ_LOCAL_COMPLETED, 130 __RQ_LOCAL_OK, 131 132 /* 76543 133 * 00000: no network possible 134 * 00001: to be send 135 * 00011: to be send, on worker queue 136 * 00101: sent, expecting recv_ack (B) or write_ack (C) 137 * 11101: sent, 138 * recv_ack (B) or implicit "ack" (A), 139 * still waiting for the barrier ack. 140 * master_bio may already be completed and invalidated. 141 * 11100: write_acked (C), 142 * data_received (for remote read, any protocol) 143 * or finally the barrier ack has arrived (B,A)... 144 * request can be freed 145 * 01100: neg-acked (write, protocol C) 146 * or neg-d-acked (read, any protocol) 147 * or killed from the transfer log 148 * during cleanup after connection loss 149 * request can be freed 150 * 01000: canceled or send failed... 151 * request can be freed 152 */ 153 154 /* if "SENT" is not set, yet, this can still fail or be canceled. 155 * if "SENT" is set already, we still wait for an Ack packet. 156 * when cleared, the master_bio may be completed. 157 * in (B,A) the request object may still linger on the transaction log 158 * until the corresponding barrier ack comes in */ 159 __RQ_NET_PENDING, 160 161 /* If it is QUEUED, and it is a WRITE, it is also registered in the 162 * transfer log. Currently we need this flag to avoid conflicts between 163 * worker canceling the request and tl_clear_barrier killing it from 164 * transfer log. We should restructure the code so this conflict does 165 * no longer occur. */ 166 __RQ_NET_QUEUED, 167 168 /* well, actually only "handed over to the network stack". 169 * 170 * TODO can potentially be dropped because of the similar meaning 171 * of RQ_NET_SENT and ~RQ_NET_QUEUED. 172 * however it is not exactly the same. before we drop it 173 * we must ensure that we can tell a request with network part 174 * from a request without, regardless of what happens to it. */ 175 __RQ_NET_SENT, 176 177 /* when set, the request may be freed (if RQ_NET_QUEUED is clear). 178 * basically this means the corresponding P_BARRIER_ACK was received */ 179 __RQ_NET_DONE, 180 181 /* whether or not we know (C) or pretend (B,A) that the write 182 * was successfully written on the peer. 183 */ 184 __RQ_NET_OK, 185 186 /* peer called drbd_set_in_sync() for this write */ 187 __RQ_NET_SIS, 188 189 /* keep this last, its for the RQ_NET_MASK */ 190 __RQ_NET_MAX, 191 192 /* Set when this is a write, clear for a read */ 193 __RQ_WRITE, 194 195 /* Should call drbd_al_complete_io() for this request... */ 196 __RQ_IN_ACT_LOG, 197 }; 198 199 #define RQ_LOCAL_PENDING (1UL << __RQ_LOCAL_PENDING) 200 #define RQ_LOCAL_COMPLETED (1UL << __RQ_LOCAL_COMPLETED) 201 #define RQ_LOCAL_OK (1UL << __RQ_LOCAL_OK) 202 203 #define RQ_LOCAL_MASK ((RQ_LOCAL_OK << 1)-1) /* 0x07 */ 204 205 #define RQ_NET_PENDING (1UL << __RQ_NET_PENDING) 206 #define RQ_NET_QUEUED (1UL << __RQ_NET_QUEUED) 207 #define RQ_NET_SENT (1UL << __RQ_NET_SENT) 208 #define RQ_NET_DONE (1UL << __RQ_NET_DONE) 209 #define RQ_NET_OK (1UL << __RQ_NET_OK) 210 #define RQ_NET_SIS (1UL << __RQ_NET_SIS) 211 212 /* 0x1f8 */ 213 #define RQ_NET_MASK (((1UL << __RQ_NET_MAX)-1) & ~RQ_LOCAL_MASK) 214 215 #define RQ_WRITE (1UL << __RQ_WRITE) 216 #define RQ_IN_ACT_LOG (1UL << __RQ_IN_ACT_LOG) 217 218 /* For waking up the frozen transfer log mod_req() has to return if the request 219 should be counted in the epoch object*/ 220 #define MR_WRITE_SHIFT 0 221 #define MR_WRITE (1 << MR_WRITE_SHIFT) 222 #define MR_READ_SHIFT 1 223 #define MR_READ (1 << MR_READ_SHIFT) 224 225 /* epoch entries */ 226 static inline 227 struct hlist_head *ee_hash_slot(struct drbd_conf *mdev, sector_t sector) 228 { 229 BUG_ON(mdev->ee_hash_s == 0); 230 return mdev->ee_hash + 231 ((unsigned int)(sector>>HT_SHIFT) % mdev->ee_hash_s); 232 } 233 234 /* transfer log (drbd_request objects) */ 235 static inline 236 struct hlist_head *tl_hash_slot(struct drbd_conf *mdev, sector_t sector) 237 { 238 BUG_ON(mdev->tl_hash_s == 0); 239 return mdev->tl_hash + 240 ((unsigned int)(sector>>HT_SHIFT) % mdev->tl_hash_s); 241 } 242 243 /* application reads (drbd_request objects) */ 244 static struct hlist_head *ar_hash_slot(struct drbd_conf *mdev, sector_t sector) 245 { 246 return mdev->app_reads_hash 247 + ((unsigned int)(sector) % APP_R_HSIZE); 248 } 249 250 /* when we receive the answer for a read request, 251 * verify that we actually know about it */ 252 static inline struct drbd_request *_ar_id_to_req(struct drbd_conf *mdev, 253 u64 id, sector_t sector) 254 { 255 struct hlist_head *slot = ar_hash_slot(mdev, sector); 256 struct hlist_node *n; 257 struct drbd_request *req; 258 259 hlist_for_each_entry(req, n, slot, collision) { 260 if ((unsigned long)req == (unsigned long)id) { 261 D_ASSERT(req->sector == sector); 262 return req; 263 } 264 } 265 return NULL; 266 } 267 268 static inline void drbd_req_make_private_bio(struct drbd_request *req, struct bio *bio_src) 269 { 270 struct bio *bio; 271 bio = bio_clone(bio_src, GFP_NOIO); /* XXX cannot fail?? */ 272 273 req->private_bio = bio; 274 275 bio->bi_private = req; 276 bio->bi_end_io = drbd_endio_pri; 277 bio->bi_next = NULL; 278 } 279 280 static inline struct drbd_request *drbd_req_new(struct drbd_conf *mdev, 281 struct bio *bio_src) 282 { 283 struct drbd_request *req = 284 mempool_alloc(drbd_request_mempool, GFP_NOIO); 285 if (likely(req)) { 286 drbd_req_make_private_bio(req, bio_src); 287 288 req->rq_state = bio_data_dir(bio_src) == WRITE ? RQ_WRITE : 0; 289 req->mdev = mdev; 290 req->master_bio = bio_src; 291 req->epoch = 0; 292 req->sector = bio_src->bi_sector; 293 req->size = bio_src->bi_size; 294 INIT_HLIST_NODE(&req->collision); 295 INIT_LIST_HEAD(&req->tl_requests); 296 INIT_LIST_HEAD(&req->w.list); 297 } 298 return req; 299 } 300 301 static inline void drbd_req_free(struct drbd_request *req) 302 { 303 mempool_free(req, drbd_request_mempool); 304 } 305 306 static inline int overlaps(sector_t s1, int l1, sector_t s2, int l2) 307 { 308 return !((s1 + (l1>>9) <= s2) || (s1 >= s2 + (l2>>9))); 309 } 310 311 /* Short lived temporary struct on the stack. 312 * We could squirrel the error to be returned into 313 * bio->bi_size, or similar. But that would be too ugly. */ 314 struct bio_and_error { 315 struct bio *bio; 316 int error; 317 }; 318 319 extern void _req_may_be_done(struct drbd_request *req, 320 struct bio_and_error *m); 321 extern int __req_mod(struct drbd_request *req, enum drbd_req_event what, 322 struct bio_and_error *m); 323 extern void complete_master_bio(struct drbd_conf *mdev, 324 struct bio_and_error *m); 325 extern void request_timer_fn(unsigned long data); 326 extern void tl_restart(struct drbd_conf *mdev, enum drbd_req_event what); 327 328 /* use this if you don't want to deal with calling complete_master_bio() 329 * outside the spinlock, e.g. when walking some list on cleanup. */ 330 static inline int _req_mod(struct drbd_request *req, enum drbd_req_event what) 331 { 332 struct drbd_conf *mdev = req->mdev; 333 struct bio_and_error m; 334 int rv; 335 336 /* __req_mod possibly frees req, do not touch req after that! */ 337 rv = __req_mod(req, what, &m); 338 if (m.bio) 339 complete_master_bio(mdev, &m); 340 341 return rv; 342 } 343 344 /* completion of master bio is outside of our spinlock. 345 * We still may or may not be inside some irqs disabled section 346 * of the lower level driver completion callback, so we need to 347 * spin_lock_irqsave here. */ 348 static inline int req_mod(struct drbd_request *req, 349 enum drbd_req_event what) 350 { 351 unsigned long flags; 352 struct drbd_conf *mdev = req->mdev; 353 struct bio_and_error m; 354 int rv; 355 356 spin_lock_irqsave(&mdev->req_lock, flags); 357 rv = __req_mod(req, what, &m); 358 spin_unlock_irqrestore(&mdev->req_lock, flags); 359 360 if (m.bio) 361 complete_master_bio(mdev, &m); 362 363 return rv; 364 } 365 366 static inline bool drbd_should_do_remote(union drbd_state s) 367 { 368 return s.pdsk == D_UP_TO_DATE || 369 (s.pdsk >= D_INCONSISTENT && 370 s.conn >= C_WF_BITMAP_T && 371 s.conn < C_AHEAD); 372 /* Before proto 96 that was >= CONNECTED instead of >= C_WF_BITMAP_T. 373 That is equivalent since before 96 IO was frozen in the C_WF_BITMAP* 374 states. */ 375 } 376 static inline bool drbd_should_send_oos(union drbd_state s) 377 { 378 return s.conn == C_AHEAD || s.conn == C_WF_BITMAP_S; 379 /* pdsk = D_INCONSISTENT as a consequence. Protocol 96 check not necessary 380 since we enter state C_AHEAD only if proto >= 96 */ 381 } 382 383 #endif 384