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 abort_disk_io, 109 completed_ok, 110 resend, 111 fail_frozen_disk_io, 112 restart_frozen_disk_io, 113 nothing, /* for tracing only */ 114 }; 115 116 /* encoding of request states for now. we don't actually need that many bits. 117 * we don't need to do atomic bit operations either, since most of the time we 118 * need to look at the connection state and/or manipulate some lists at the 119 * same time, so we should hold the request lock anyways. 120 */ 121 enum drbd_req_state_bits { 122 /* 3210 123 * 0000: no local possible 124 * 0001: to be submitted 125 * UNUSED, we could map: 011: submitted, completion still pending 126 * 0110: completed ok 127 * 0010: completed with error 128 * 1001: Aborted (before completion) 129 * 1x10: Aborted and completed -> free 130 */ 131 __RQ_LOCAL_PENDING, 132 __RQ_LOCAL_COMPLETED, 133 __RQ_LOCAL_OK, 134 __RQ_LOCAL_ABORTED, 135 136 /* 87654 137 * 00000: no network possible 138 * 00001: to be send 139 * 00011: to be send, on worker queue 140 * 00101: sent, expecting recv_ack (B) or write_ack (C) 141 * 11101: sent, 142 * recv_ack (B) or implicit "ack" (A), 143 * still waiting for the barrier ack. 144 * master_bio may already be completed and invalidated. 145 * 11100: write_acked (C), 146 * data_received (for remote read, any protocol) 147 * or finally the barrier ack has arrived (B,A)... 148 * request can be freed 149 * 01100: neg-acked (write, protocol C) 150 * or neg-d-acked (read, any protocol) 151 * or killed from the transfer log 152 * during cleanup after connection loss 153 * request can be freed 154 * 01000: canceled or send failed... 155 * request can be freed 156 */ 157 158 /* if "SENT" is not set, yet, this can still fail or be canceled. 159 * if "SENT" is set already, we still wait for an Ack packet. 160 * when cleared, the master_bio may be completed. 161 * in (B,A) the request object may still linger on the transaction log 162 * until the corresponding barrier ack comes in */ 163 __RQ_NET_PENDING, 164 165 /* If it is QUEUED, and it is a WRITE, it is also registered in the 166 * transfer log. Currently we need this flag to avoid conflicts between 167 * worker canceling the request and tl_clear_barrier killing it from 168 * transfer log. We should restructure the code so this conflict does 169 * no longer occur. */ 170 __RQ_NET_QUEUED, 171 172 /* well, actually only "handed over to the network stack". 173 * 174 * TODO can potentially be dropped because of the similar meaning 175 * of RQ_NET_SENT and ~RQ_NET_QUEUED. 176 * however it is not exactly the same. before we drop it 177 * we must ensure that we can tell a request with network part 178 * from a request without, regardless of what happens to it. */ 179 __RQ_NET_SENT, 180 181 /* when set, the request may be freed (if RQ_NET_QUEUED is clear). 182 * basically this means the corresponding P_BARRIER_ACK was received */ 183 __RQ_NET_DONE, 184 185 /* whether or not we know (C) or pretend (B,A) that the write 186 * was successfully written on the peer. 187 */ 188 __RQ_NET_OK, 189 190 /* peer called drbd_set_in_sync() for this write */ 191 __RQ_NET_SIS, 192 193 /* keep this last, its for the RQ_NET_MASK */ 194 __RQ_NET_MAX, 195 196 /* Set when this is a write, clear for a read */ 197 __RQ_WRITE, 198 199 /* Should call drbd_al_complete_io() for this request... */ 200 __RQ_IN_ACT_LOG, 201 }; 202 203 #define RQ_LOCAL_PENDING (1UL << __RQ_LOCAL_PENDING) 204 #define RQ_LOCAL_COMPLETED (1UL << __RQ_LOCAL_COMPLETED) 205 #define RQ_LOCAL_OK (1UL << __RQ_LOCAL_OK) 206 #define RQ_LOCAL_ABORTED (1UL << __RQ_LOCAL_ABORTED) 207 208 #define RQ_LOCAL_MASK ((RQ_LOCAL_ABORTED << 1)-1) 209 210 #define RQ_NET_PENDING (1UL << __RQ_NET_PENDING) 211 #define RQ_NET_QUEUED (1UL << __RQ_NET_QUEUED) 212 #define RQ_NET_SENT (1UL << __RQ_NET_SENT) 213 #define RQ_NET_DONE (1UL << __RQ_NET_DONE) 214 #define RQ_NET_OK (1UL << __RQ_NET_OK) 215 #define RQ_NET_SIS (1UL << __RQ_NET_SIS) 216 217 /* 0x1f8 */ 218 #define RQ_NET_MASK (((1UL << __RQ_NET_MAX)-1) & ~RQ_LOCAL_MASK) 219 220 #define RQ_WRITE (1UL << __RQ_WRITE) 221 #define RQ_IN_ACT_LOG (1UL << __RQ_IN_ACT_LOG) 222 223 /* For waking up the frozen transfer log mod_req() has to return if the request 224 should be counted in the epoch object*/ 225 #define MR_WRITE_SHIFT 0 226 #define MR_WRITE (1 << MR_WRITE_SHIFT) 227 #define MR_READ_SHIFT 1 228 #define MR_READ (1 << MR_READ_SHIFT) 229 230 /* epoch entries */ 231 static inline 232 struct hlist_head *ee_hash_slot(struct drbd_conf *mdev, sector_t sector) 233 { 234 BUG_ON(mdev->ee_hash_s == 0); 235 return mdev->ee_hash + 236 ((unsigned int)(sector>>HT_SHIFT) % mdev->ee_hash_s); 237 } 238 239 /* transfer log (drbd_request objects) */ 240 static inline 241 struct hlist_head *tl_hash_slot(struct drbd_conf *mdev, sector_t sector) 242 { 243 BUG_ON(mdev->tl_hash_s == 0); 244 return mdev->tl_hash + 245 ((unsigned int)(sector>>HT_SHIFT) % mdev->tl_hash_s); 246 } 247 248 /* application reads (drbd_request objects) */ 249 static struct hlist_head *ar_hash_slot(struct drbd_conf *mdev, sector_t sector) 250 { 251 return mdev->app_reads_hash 252 + ((unsigned int)(sector) % APP_R_HSIZE); 253 } 254 255 /* when we receive the answer for a read request, 256 * verify that we actually know about it */ 257 static inline struct drbd_request *_ar_id_to_req(struct drbd_conf *mdev, 258 u64 id, sector_t sector) 259 { 260 struct hlist_head *slot = ar_hash_slot(mdev, sector); 261 struct hlist_node *n; 262 struct drbd_request *req; 263 264 hlist_for_each_entry(req, n, slot, collision) { 265 if ((unsigned long)req == (unsigned long)id) { 266 D_ASSERT(req->sector == sector); 267 return req; 268 } 269 } 270 return NULL; 271 } 272 273 static inline void drbd_req_make_private_bio(struct drbd_request *req, struct bio *bio_src) 274 { 275 struct bio *bio; 276 bio = bio_clone(bio_src, GFP_NOIO); /* XXX cannot fail?? */ 277 278 req->private_bio = bio; 279 280 bio->bi_private = req; 281 bio->bi_end_io = drbd_endio_pri; 282 bio->bi_next = NULL; 283 } 284 285 static inline struct drbd_request *drbd_req_new(struct drbd_conf *mdev, 286 struct bio *bio_src) 287 { 288 struct drbd_request *req = 289 mempool_alloc(drbd_request_mempool, GFP_NOIO); 290 if (likely(req)) { 291 drbd_req_make_private_bio(req, bio_src); 292 293 req->rq_state = bio_data_dir(bio_src) == WRITE ? RQ_WRITE : 0; 294 req->mdev = mdev; 295 req->master_bio = bio_src; 296 req->epoch = 0; 297 req->sector = bio_src->bi_sector; 298 req->size = bio_src->bi_size; 299 INIT_HLIST_NODE(&req->collision); 300 INIT_LIST_HEAD(&req->tl_requests); 301 INIT_LIST_HEAD(&req->w.list); 302 } 303 return req; 304 } 305 306 static inline void drbd_req_free(struct drbd_request *req) 307 { 308 mempool_free(req, drbd_request_mempool); 309 } 310 311 static inline int overlaps(sector_t s1, int l1, sector_t s2, int l2) 312 { 313 return !((s1 + (l1>>9) <= s2) || (s1 >= s2 + (l2>>9))); 314 } 315 316 /* Short lived temporary struct on the stack. 317 * We could squirrel the error to be returned into 318 * bio->bi_size, or similar. But that would be too ugly. */ 319 struct bio_and_error { 320 struct bio *bio; 321 int error; 322 }; 323 324 extern void _req_may_be_done(struct drbd_request *req, 325 struct bio_and_error *m); 326 extern int __req_mod(struct drbd_request *req, enum drbd_req_event what, 327 struct bio_and_error *m); 328 extern void complete_master_bio(struct drbd_conf *mdev, 329 struct bio_and_error *m); 330 extern void request_timer_fn(unsigned long data); 331 extern void tl_restart(struct drbd_conf *mdev, enum drbd_req_event what); 332 333 /* use this if you don't want to deal with calling complete_master_bio() 334 * outside the spinlock, e.g. when walking some list on cleanup. */ 335 static inline int _req_mod(struct drbd_request *req, enum drbd_req_event what) 336 { 337 struct drbd_conf *mdev = req->mdev; 338 struct bio_and_error m; 339 int rv; 340 341 /* __req_mod possibly frees req, do not touch req after that! */ 342 rv = __req_mod(req, what, &m); 343 if (m.bio) 344 complete_master_bio(mdev, &m); 345 346 return rv; 347 } 348 349 /* completion of master bio is outside of our spinlock. 350 * We still may or may not be inside some irqs disabled section 351 * of the lower level driver completion callback, so we need to 352 * spin_lock_irqsave here. */ 353 static inline int req_mod(struct drbd_request *req, 354 enum drbd_req_event what) 355 { 356 unsigned long flags; 357 struct drbd_conf *mdev = req->mdev; 358 struct bio_and_error m; 359 int rv; 360 361 spin_lock_irqsave(&mdev->req_lock, flags); 362 rv = __req_mod(req, what, &m); 363 spin_unlock_irqrestore(&mdev->req_lock, flags); 364 365 if (m.bio) 366 complete_master_bio(mdev, &m); 367 368 return rv; 369 } 370 371 static inline bool drbd_should_do_remote(union drbd_state s) 372 { 373 return s.pdsk == D_UP_TO_DATE || 374 (s.pdsk >= D_INCONSISTENT && 375 s.conn >= C_WF_BITMAP_T && 376 s.conn < C_AHEAD); 377 /* Before proto 96 that was >= CONNECTED instead of >= C_WF_BITMAP_T. 378 That is equivalent since before 96 IO was frozen in the C_WF_BITMAP* 379 states. */ 380 } 381 static inline bool drbd_should_send_oos(union drbd_state s) 382 { 383 return s.conn == C_AHEAD || s.conn == C_WF_BITMAP_S; 384 /* pdsk = D_INCONSISTENT as a consequence. Protocol 96 check not necessary 385 since we enter state C_AHEAD only if proto >= 96 */ 386 } 387 388 #endif 389