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_SENT, 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 /* An empty flush is queued as P_BARRIER, 92 * which will cause it to complete "successfully", 93 * even if the local disk flush failed. 94 * 95 * Just like "real" requests, empty flushes (blkdev_issue_flush()) will 96 * only see an error if neither local nor remote data is reachable. */ 97 QUEUE_AS_DRBD_BARRIER, 98 99 SEND_CANCELED, 100 SEND_FAILED, 101 HANDED_OVER_TO_NETWORK, 102 OOS_HANDED_TO_NETWORK, 103 CONNECTION_LOST_WHILE_PENDING, 104 READ_RETRY_REMOTE_CANCELED, 105 RECV_ACKED_BY_PEER, 106 WRITE_ACKED_BY_PEER, 107 WRITE_ACKED_BY_PEER_AND_SIS, /* and set_in_sync */ 108 CONFLICT_RESOLVED, 109 POSTPONE_WRITE, 110 NEG_ACKED, 111 BARRIER_ACKED, /* in protocol A and B */ 112 DATA_RECEIVED, /* (remote read) */ 113 114 READ_COMPLETED_WITH_ERROR, 115 READ_AHEAD_COMPLETED_WITH_ERROR, 116 WRITE_COMPLETED_WITH_ERROR, 117 ABORT_DISK_IO, 118 COMPLETED_OK, 119 RESEND, 120 FAIL_FROZEN_DISK_IO, 121 RESTART_FROZEN_DISK_IO, 122 NOTHING, 123 }; 124 125 /* encoding of request states for now. we don't actually need that many bits. 126 * we don't need to do atomic bit operations either, since most of the time we 127 * need to look at the connection state and/or manipulate some lists at the 128 * same time, so we should hold the request lock anyways. 129 */ 130 enum drbd_req_state_bits { 131 /* 3210 132 * 0000: no local possible 133 * 0001: to be submitted 134 * UNUSED, we could map: 011: submitted, completion still pending 135 * 0110: completed ok 136 * 0010: completed with error 137 * 1001: Aborted (before completion) 138 * 1x10: Aborted and completed -> free 139 */ 140 __RQ_LOCAL_PENDING, 141 __RQ_LOCAL_COMPLETED, 142 __RQ_LOCAL_OK, 143 __RQ_LOCAL_ABORTED, 144 145 /* 87654 146 * 00000: no network possible 147 * 00001: to be send 148 * 00011: to be send, on worker queue 149 * 00101: sent, expecting recv_ack (B) or write_ack (C) 150 * 11101: sent, 151 * recv_ack (B) or implicit "ack" (A), 152 * still waiting for the barrier ack. 153 * master_bio may already be completed and invalidated. 154 * 11100: write acked (C), 155 * data received (for remote read, any protocol) 156 * or finally the barrier ack has arrived (B,A)... 157 * request can be freed 158 * 01100: neg-acked (write, protocol C) 159 * or neg-d-acked (read, any protocol) 160 * or killed from the transfer log 161 * during cleanup after connection loss 162 * request can be freed 163 * 01000: canceled or send failed... 164 * request can be freed 165 */ 166 167 /* if "SENT" is not set, yet, this can still fail or be canceled. 168 * if "SENT" is set already, we still wait for an Ack packet. 169 * when cleared, the master_bio may be completed. 170 * in (B,A) the request object may still linger on the transaction log 171 * until the corresponding barrier ack comes in */ 172 __RQ_NET_PENDING, 173 174 /* If it is QUEUED, and it is a WRITE, it is also registered in the 175 * transfer log. Currently we need this flag to avoid conflicts between 176 * worker canceling the request and tl_clear_barrier killing it from 177 * transfer log. We should restructure the code so this conflict does 178 * no longer occur. */ 179 __RQ_NET_QUEUED, 180 181 /* well, actually only "handed over to the network stack". 182 * 183 * TODO can potentially be dropped because of the similar meaning 184 * of RQ_NET_SENT and ~RQ_NET_QUEUED. 185 * however it is not exactly the same. before we drop it 186 * we must ensure that we can tell a request with network part 187 * from a request without, regardless of what happens to it. */ 188 __RQ_NET_SENT, 189 190 /* when set, the request may be freed (if RQ_NET_QUEUED is clear). 191 * basically this means the corresponding P_BARRIER_ACK was received */ 192 __RQ_NET_DONE, 193 194 /* whether or not we know (C) or pretend (B,A) that the write 195 * was successfully written on the peer. 196 */ 197 __RQ_NET_OK, 198 199 /* peer called drbd_set_in_sync() for this write */ 200 __RQ_NET_SIS, 201 202 /* keep this last, its for the RQ_NET_MASK */ 203 __RQ_NET_MAX, 204 205 /* Set when this is a write, clear for a read */ 206 __RQ_WRITE, 207 208 /* Should call drbd_al_complete_io() for this request... */ 209 __RQ_IN_ACT_LOG, 210 211 /* The peer has sent a retry ACK */ 212 __RQ_POSTPONED, 213 214 /* would have been completed, 215 * but was not, because of drbd_suspended() */ 216 __RQ_COMPLETION_SUSP, 217 218 /* We expect a receive ACK (wire proto B) */ 219 __RQ_EXP_RECEIVE_ACK, 220 221 /* We expect a write ACK (wite proto C) */ 222 __RQ_EXP_WRITE_ACK, 223 224 /* waiting for a barrier ack, did an extra kref_get */ 225 __RQ_EXP_BARR_ACK, 226 }; 227 228 #define RQ_LOCAL_PENDING (1UL << __RQ_LOCAL_PENDING) 229 #define RQ_LOCAL_COMPLETED (1UL << __RQ_LOCAL_COMPLETED) 230 #define RQ_LOCAL_OK (1UL << __RQ_LOCAL_OK) 231 #define RQ_LOCAL_ABORTED (1UL << __RQ_LOCAL_ABORTED) 232 233 #define RQ_LOCAL_MASK ((RQ_LOCAL_ABORTED << 1)-1) 234 235 #define RQ_NET_PENDING (1UL << __RQ_NET_PENDING) 236 #define RQ_NET_QUEUED (1UL << __RQ_NET_QUEUED) 237 #define RQ_NET_SENT (1UL << __RQ_NET_SENT) 238 #define RQ_NET_DONE (1UL << __RQ_NET_DONE) 239 #define RQ_NET_OK (1UL << __RQ_NET_OK) 240 #define RQ_NET_SIS (1UL << __RQ_NET_SIS) 241 242 /* 0x1f8 */ 243 #define RQ_NET_MASK (((1UL << __RQ_NET_MAX)-1) & ~RQ_LOCAL_MASK) 244 245 #define RQ_WRITE (1UL << __RQ_WRITE) 246 #define RQ_IN_ACT_LOG (1UL << __RQ_IN_ACT_LOG) 247 #define RQ_POSTPONED (1UL << __RQ_POSTPONED) 248 #define RQ_COMPLETION_SUSP (1UL << __RQ_COMPLETION_SUSP) 249 #define RQ_EXP_RECEIVE_ACK (1UL << __RQ_EXP_RECEIVE_ACK) 250 #define RQ_EXP_WRITE_ACK (1UL << __RQ_EXP_WRITE_ACK) 251 #define RQ_EXP_BARR_ACK (1UL << __RQ_EXP_BARR_ACK) 252 253 /* For waking up the frozen transfer log mod_req() has to return if the request 254 should be counted in the epoch object*/ 255 #define MR_WRITE 1 256 #define MR_READ 2 257 258 static inline void drbd_req_make_private_bio(struct drbd_request *req, struct bio *bio_src) 259 { 260 struct bio *bio; 261 bio = bio_clone(bio_src, GFP_NOIO); /* XXX cannot fail?? */ 262 263 req->private_bio = bio; 264 265 bio->bi_private = req; 266 bio->bi_end_io = drbd_request_endio; 267 bio->bi_next = NULL; 268 } 269 270 /* Short lived temporary struct on the stack. 271 * We could squirrel the error to be returned into 272 * bio->bi_iter.bi_size, or similar. But that would be too ugly. */ 273 struct bio_and_error { 274 struct bio *bio; 275 int error; 276 }; 277 278 extern void start_new_tl_epoch(struct drbd_tconn *tconn); 279 extern void drbd_req_destroy(struct kref *kref); 280 extern void _req_may_be_done(struct drbd_request *req, 281 struct bio_and_error *m); 282 extern int __req_mod(struct drbd_request *req, enum drbd_req_event what, 283 struct bio_and_error *m); 284 extern void complete_master_bio(struct drbd_device *device, 285 struct bio_and_error *m); 286 extern void request_timer_fn(unsigned long data); 287 extern void tl_restart(struct drbd_tconn *tconn, enum drbd_req_event what); 288 extern void _tl_restart(struct drbd_tconn *tconn, enum drbd_req_event what); 289 290 /* this is in drbd_main.c */ 291 extern void drbd_restart_request(struct drbd_request *req); 292 293 /* use this if you don't want to deal with calling complete_master_bio() 294 * outside the spinlock, e.g. when walking some list on cleanup. */ 295 static inline int _req_mod(struct drbd_request *req, enum drbd_req_event what) 296 { 297 struct drbd_device *device = req->w.device; 298 struct bio_and_error m; 299 int rv; 300 301 /* __req_mod possibly frees req, do not touch req after that! */ 302 rv = __req_mod(req, what, &m); 303 if (m.bio) 304 complete_master_bio(device, &m); 305 306 return rv; 307 } 308 309 /* completion of master bio is outside of our spinlock. 310 * We still may or may not be inside some irqs disabled section 311 * of the lower level driver completion callback, so we need to 312 * spin_lock_irqsave here. */ 313 static inline int req_mod(struct drbd_request *req, 314 enum drbd_req_event what) 315 { 316 unsigned long flags; 317 struct drbd_device *device = req->w.device; 318 struct bio_and_error m; 319 int rv; 320 321 spin_lock_irqsave(&device->tconn->req_lock, flags); 322 rv = __req_mod(req, what, &m); 323 spin_unlock_irqrestore(&device->tconn->req_lock, flags); 324 325 if (m.bio) 326 complete_master_bio(device, &m); 327 328 return rv; 329 } 330 331 static inline bool drbd_should_do_remote(union drbd_dev_state s) 332 { 333 return s.pdsk == D_UP_TO_DATE || 334 (s.pdsk >= D_INCONSISTENT && 335 s.conn >= C_WF_BITMAP_T && 336 s.conn < C_AHEAD); 337 /* Before proto 96 that was >= CONNECTED instead of >= C_WF_BITMAP_T. 338 That is equivalent since before 96 IO was frozen in the C_WF_BITMAP* 339 states. */ 340 } 341 static inline bool drbd_should_send_out_of_sync(union drbd_dev_state s) 342 { 343 return s.conn == C_AHEAD || s.conn == C_WF_BITMAP_S; 344 /* pdsk = D_INCONSISTENT as a consequence. Protocol 96 check not necessary 345 since we enter state C_AHEAD only if proto >= 96 */ 346 } 347 348 #endif 349