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 34 /* The request callbacks will be called in irq context by the IDE drivers, 35 and in Softirqs/Tasklets/BH context by the SCSI drivers, 36 and by the receiver and worker in kernel-thread context. 37 Try to get the locking right :) */ 38 39 /* 40 * Objects of type struct drbd_request do only exist on a R_PRIMARY node, and are 41 * associated with IO requests originating from the block layer above us. 42 * 43 * There are quite a few things that may happen to a drbd request 44 * during its lifetime. 45 * 46 * It will be created. 47 * It will be marked with the intention to be 48 * submitted to local disk and/or 49 * send via the network. 50 * 51 * It has to be placed on the transfer log and other housekeeping lists, 52 * In case we have a network connection. 53 * 54 * It may be identified as a concurrent (write) request 55 * and be handled accordingly. 56 * 57 * It may me handed over to the local disk subsystem. 58 * It may be completed by the local disk subsystem, 59 * either successfully or with io-error. 60 * In case it is a READ request, and it failed locally, 61 * it may be retried remotely. 62 * 63 * It may be queued for sending. 64 * It may be handed over to the network stack, 65 * which may fail. 66 * It may be acknowledged by the "peer" according to the wire_protocol in use. 67 * this may be a negative ack. 68 * It may receive a faked ack when the network connection is lost and the 69 * transfer log is cleaned up. 70 * Sending may be canceled due to network connection loss. 71 * When it finally has outlived its time, 72 * corresponding dirty bits in the resync-bitmap may be cleared or set, 73 * it will be destroyed, 74 * and completion will be signalled to the originator, 75 * with or without "success". 76 */ 77 78 enum drbd_req_event { 79 CREATED, 80 TO_BE_SENT, 81 TO_BE_SUBMITTED, 82 83 /* XXX yes, now I am inconsistent... 84 * these are not "events" but "actions" 85 * oh, well... */ 86 QUEUE_FOR_NET_WRITE, 87 QUEUE_FOR_NET_READ, 88 QUEUE_FOR_SEND_OOS, 89 90 /* An empty flush is queued as P_BARRIER, 91 * which will cause it to complete "successfully", 92 * even if the local disk flush failed. 93 * 94 * Just like "real" requests, empty flushes (blkdev_issue_flush()) will 95 * only see an error if neither local nor remote data is reachable. */ 96 QUEUE_AS_DRBD_BARRIER, 97 98 SEND_CANCELED, 99 SEND_FAILED, 100 HANDED_OVER_TO_NETWORK, 101 OOS_HANDED_TO_NETWORK, 102 CONNECTION_LOST_WHILE_PENDING, 103 READ_RETRY_REMOTE_CANCELED, 104 RECV_ACKED_BY_PEER, 105 WRITE_ACKED_BY_PEER, 106 WRITE_ACKED_BY_PEER_AND_SIS, /* and set_in_sync */ 107 CONFLICT_RESOLVED, 108 POSTPONE_WRITE, 109 NEG_ACKED, 110 BARRIER_ACKED, /* in protocol A and B */ 111 DATA_RECEIVED, /* (remote read) */ 112 113 COMPLETED_OK, 114 READ_COMPLETED_WITH_ERROR, 115 READ_AHEAD_COMPLETED_WITH_ERROR, 116 WRITE_COMPLETED_WITH_ERROR, 117 DISCARD_COMPLETED_NOTSUPP, 118 DISCARD_COMPLETED_WITH_ERROR, 119 120 ABORT_DISK_IO, 121 RESEND, 122 FAIL_FROZEN_DISK_IO, 123 RESTART_FROZEN_DISK_IO, 124 NOTHING, 125 }; 126 127 /* encoding of request states for now. we don't actually need that many bits. 128 * we don't need to do atomic bit operations either, since most of the time we 129 * need to look at the connection state and/or manipulate some lists at the 130 * same time, so we should hold the request lock anyways. 131 */ 132 enum drbd_req_state_bits { 133 /* 3210 134 * 0000: no local possible 135 * 0001: to be submitted 136 * UNUSED, we could map: 011: submitted, completion still pending 137 * 0110: completed ok 138 * 0010: completed with error 139 * 1001: Aborted (before completion) 140 * 1x10: Aborted and completed -> free 141 */ 142 __RQ_LOCAL_PENDING, 143 __RQ_LOCAL_COMPLETED, 144 __RQ_LOCAL_OK, 145 __RQ_LOCAL_ABORTED, 146 147 /* 87654 148 * 00000: no network possible 149 * 00001: to be send 150 * 00011: to be send, on worker queue 151 * 00101: sent, expecting recv_ack (B) or write_ack (C) 152 * 11101: sent, 153 * recv_ack (B) or implicit "ack" (A), 154 * still waiting for the barrier ack. 155 * master_bio may already be completed and invalidated. 156 * 11100: write acked (C), 157 * data received (for remote read, any protocol) 158 * or finally the barrier ack has arrived (B,A)... 159 * request can be freed 160 * 01100: neg-acked (write, protocol C) 161 * or neg-d-acked (read, any protocol) 162 * or killed from the transfer log 163 * during cleanup after connection loss 164 * request can be freed 165 * 01000: canceled or send failed... 166 * request can be freed 167 */ 168 169 /* if "SENT" is not set, yet, this can still fail or be canceled. 170 * if "SENT" is set already, we still wait for an Ack packet. 171 * when cleared, the master_bio may be completed. 172 * in (B,A) the request object may still linger on the transaction log 173 * until the corresponding barrier ack comes in */ 174 __RQ_NET_PENDING, 175 176 /* If it is QUEUED, and it is a WRITE, it is also registered in the 177 * transfer log. Currently we need this flag to avoid conflicts between 178 * worker canceling the request and tl_clear_barrier killing it from 179 * transfer log. We should restructure the code so this conflict does 180 * no longer occur. */ 181 __RQ_NET_QUEUED, 182 183 /* well, actually only "handed over to the network stack". 184 * 185 * TODO can potentially be dropped because of the similar meaning 186 * of RQ_NET_SENT and ~RQ_NET_QUEUED. 187 * however it is not exactly the same. before we drop it 188 * we must ensure that we can tell a request with network part 189 * from a request without, regardless of what happens to it. */ 190 __RQ_NET_SENT, 191 192 /* when set, the request may be freed (if RQ_NET_QUEUED is clear). 193 * basically this means the corresponding P_BARRIER_ACK was received */ 194 __RQ_NET_DONE, 195 196 /* whether or not we know (C) or pretend (B,A) that the write 197 * was successfully written on the peer. 198 */ 199 __RQ_NET_OK, 200 201 /* peer called drbd_set_in_sync() for this write */ 202 __RQ_NET_SIS, 203 204 /* keep this last, its for the RQ_NET_MASK */ 205 __RQ_NET_MAX, 206 207 /* Set when this is a write, clear for a read */ 208 __RQ_WRITE, 209 __RQ_WSAME, 210 __RQ_UNMAP, 211 212 /* Should call drbd_al_complete_io() for this request... */ 213 __RQ_IN_ACT_LOG, 214 215 /* The peer has sent a retry ACK */ 216 __RQ_POSTPONED, 217 218 /* would have been completed, 219 * but was not, because of drbd_suspended() */ 220 __RQ_COMPLETION_SUSP, 221 222 /* We expect a receive ACK (wire proto B) */ 223 __RQ_EXP_RECEIVE_ACK, 224 225 /* We expect a write ACK (wite proto C) */ 226 __RQ_EXP_WRITE_ACK, 227 228 /* waiting for a barrier ack, did an extra kref_get */ 229 __RQ_EXP_BARR_ACK, 230 }; 231 232 #define RQ_LOCAL_PENDING (1UL << __RQ_LOCAL_PENDING) 233 #define RQ_LOCAL_COMPLETED (1UL << __RQ_LOCAL_COMPLETED) 234 #define RQ_LOCAL_OK (1UL << __RQ_LOCAL_OK) 235 #define RQ_LOCAL_ABORTED (1UL << __RQ_LOCAL_ABORTED) 236 237 #define RQ_LOCAL_MASK ((RQ_LOCAL_ABORTED << 1)-1) 238 239 #define RQ_NET_PENDING (1UL << __RQ_NET_PENDING) 240 #define RQ_NET_QUEUED (1UL << __RQ_NET_QUEUED) 241 #define RQ_NET_SENT (1UL << __RQ_NET_SENT) 242 #define RQ_NET_DONE (1UL << __RQ_NET_DONE) 243 #define RQ_NET_OK (1UL << __RQ_NET_OK) 244 #define RQ_NET_SIS (1UL << __RQ_NET_SIS) 245 246 #define RQ_NET_MASK (((1UL << __RQ_NET_MAX)-1) & ~RQ_LOCAL_MASK) 247 248 #define RQ_WRITE (1UL << __RQ_WRITE) 249 #define RQ_WSAME (1UL << __RQ_WSAME) 250 #define RQ_UNMAP (1UL << __RQ_UNMAP) 251 #define RQ_IN_ACT_LOG (1UL << __RQ_IN_ACT_LOG) 252 #define RQ_POSTPONED (1UL << __RQ_POSTPONED) 253 #define RQ_COMPLETION_SUSP (1UL << __RQ_COMPLETION_SUSP) 254 #define RQ_EXP_RECEIVE_ACK (1UL << __RQ_EXP_RECEIVE_ACK) 255 #define RQ_EXP_WRITE_ACK (1UL << __RQ_EXP_WRITE_ACK) 256 #define RQ_EXP_BARR_ACK (1UL << __RQ_EXP_BARR_ACK) 257 258 /* For waking up the frozen transfer log mod_req() has to return if the request 259 should be counted in the epoch object*/ 260 #define MR_WRITE 1 261 #define MR_READ 2 262 263 static inline void drbd_req_make_private_bio(struct drbd_request *req, struct bio *bio_src) 264 { 265 struct bio *bio; 266 bio = bio_clone(bio_src, GFP_NOIO); /* XXX cannot fail?? */ 267 268 req->private_bio = bio; 269 270 bio->bi_private = req; 271 bio->bi_end_io = drbd_request_endio; 272 bio->bi_next = NULL; 273 } 274 275 /* Short lived temporary struct on the stack. 276 * We could squirrel the error to be returned into 277 * bio->bi_iter.bi_size, or similar. But that would be too ugly. */ 278 struct bio_and_error { 279 struct bio *bio; 280 int error; 281 }; 282 283 extern void start_new_tl_epoch(struct drbd_connection *connection); 284 extern void drbd_req_destroy(struct kref *kref); 285 extern void _req_may_be_done(struct drbd_request *req, 286 struct bio_and_error *m); 287 extern int __req_mod(struct drbd_request *req, enum drbd_req_event what, 288 struct bio_and_error *m); 289 extern void complete_master_bio(struct drbd_device *device, 290 struct bio_and_error *m); 291 extern void request_timer_fn(unsigned long data); 292 extern void tl_restart(struct drbd_connection *connection, enum drbd_req_event what); 293 extern void _tl_restart(struct drbd_connection *connection, enum drbd_req_event what); 294 extern void tl_abort_disk_io(struct drbd_device *device); 295 296 /* this is in drbd_main.c */ 297 extern void drbd_restart_request(struct drbd_request *req); 298 299 /* use this if you don't want to deal with calling complete_master_bio() 300 * outside the spinlock, e.g. when walking some list on cleanup. */ 301 static inline int _req_mod(struct drbd_request *req, enum drbd_req_event what) 302 { 303 struct drbd_device *device = req->device; 304 struct bio_and_error m; 305 int rv; 306 307 /* __req_mod possibly frees req, do not touch req after that! */ 308 rv = __req_mod(req, what, &m); 309 if (m.bio) 310 complete_master_bio(device, &m); 311 312 return rv; 313 } 314 315 /* completion of master bio is outside of our spinlock. 316 * We still may or may not be inside some irqs disabled section 317 * of the lower level driver completion callback, so we need to 318 * spin_lock_irqsave here. */ 319 static inline int req_mod(struct drbd_request *req, 320 enum drbd_req_event what) 321 { 322 unsigned long flags; 323 struct drbd_device *device = req->device; 324 struct bio_and_error m; 325 int rv; 326 327 spin_lock_irqsave(&device->resource->req_lock, flags); 328 rv = __req_mod(req, what, &m); 329 spin_unlock_irqrestore(&device->resource->req_lock, flags); 330 331 if (m.bio) 332 complete_master_bio(device, &m); 333 334 return rv; 335 } 336 337 extern bool drbd_should_do_remote(union drbd_dev_state); 338 339 #endif 340