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 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_RESOLVED, 101 POSTPONE_WRITE, 102 NEG_ACKED, 103 BARRIER_ACKED, /* in protocol A and B */ 104 DATA_RECEIVED, /* (remote read) */ 105 106 READ_COMPLETED_WITH_ERROR, 107 READ_AHEAD_COMPLETED_WITH_ERROR, 108 WRITE_COMPLETED_WITH_ERROR, 109 ABORT_DISK_IO, 110 COMPLETED_OK, 111 RESEND, 112 FAIL_FROZEN_DISK_IO, 113 RESTART_FROZEN_DISK_IO, 114 NOTHING, 115 }; 116 117 /* encoding of request states for now. we don't actually need that many bits. 118 * we don't need to do atomic bit operations either, since most of the time we 119 * need to look at the connection state and/or manipulate some lists at the 120 * same time, so we should hold the request lock anyways. 121 */ 122 enum drbd_req_state_bits { 123 /* 3210 124 * 0000: no local possible 125 * 0001: to be submitted 126 * UNUSED, we could map: 011: submitted, completion still pending 127 * 0110: completed ok 128 * 0010: completed with error 129 * 1001: Aborted (before completion) 130 * 1x10: Aborted and completed -> free 131 */ 132 __RQ_LOCAL_PENDING, 133 __RQ_LOCAL_COMPLETED, 134 __RQ_LOCAL_OK, 135 __RQ_LOCAL_ABORTED, 136 137 /* 87654 138 * 00000: no network possible 139 * 00001: to be send 140 * 00011: to be send, on worker queue 141 * 00101: sent, expecting recv_ack (B) or write_ack (C) 142 * 11101: sent, 143 * recv_ack (B) or implicit "ack" (A), 144 * still waiting for the barrier ack. 145 * master_bio may already be completed and invalidated. 146 * 11100: write acked (C), 147 * data received (for remote read, any protocol) 148 * or finally the barrier ack has arrived (B,A)... 149 * request can be freed 150 * 01100: neg-acked (write, protocol C) 151 * or neg-d-acked (read, any protocol) 152 * or killed from the transfer log 153 * during cleanup after connection loss 154 * request can be freed 155 * 01000: canceled or send failed... 156 * request can be freed 157 */ 158 159 /* if "SENT" is not set, yet, this can still fail or be canceled. 160 * if "SENT" is set already, we still wait for an Ack packet. 161 * when cleared, the master_bio may be completed. 162 * in (B,A) the request object may still linger on the transaction log 163 * until the corresponding barrier ack comes in */ 164 __RQ_NET_PENDING, 165 166 /* If it is QUEUED, and it is a WRITE, it is also registered in the 167 * transfer log. Currently we need this flag to avoid conflicts between 168 * worker canceling the request and tl_clear_barrier killing it from 169 * transfer log. We should restructure the code so this conflict does 170 * no longer occur. */ 171 __RQ_NET_QUEUED, 172 173 /* well, actually only "handed over to the network stack". 174 * 175 * TODO can potentially be dropped because of the similar meaning 176 * of RQ_NET_SENT and ~RQ_NET_QUEUED. 177 * however it is not exactly the same. before we drop it 178 * we must ensure that we can tell a request with network part 179 * from a request without, regardless of what happens to it. */ 180 __RQ_NET_SENT, 181 182 /* when set, the request may be freed (if RQ_NET_QUEUED is clear). 183 * basically this means the corresponding P_BARRIER_ACK was received */ 184 __RQ_NET_DONE, 185 186 /* whether or not we know (C) or pretend (B,A) that the write 187 * was successfully written on the peer. 188 */ 189 __RQ_NET_OK, 190 191 /* peer called drbd_set_in_sync() for this write */ 192 __RQ_NET_SIS, 193 194 /* keep this last, its for the RQ_NET_MASK */ 195 __RQ_NET_MAX, 196 197 /* Set when this is a write, clear for a read */ 198 __RQ_WRITE, 199 200 /* Should call drbd_al_complete_io() for this request... */ 201 __RQ_IN_ACT_LOG, 202 203 /* The peer has sent a retry ACK */ 204 __RQ_POSTPONED, 205 206 /* would have been completed, 207 * but was not, because of drbd_suspended() */ 208 __RQ_COMPLETION_SUSP, 209 210 /* We expect a receive ACK (wire proto B) */ 211 __RQ_EXP_RECEIVE_ACK, 212 213 /* We expect a write ACK (wite proto C) */ 214 __RQ_EXP_WRITE_ACK, 215 216 /* waiting for a barrier ack, did an extra kref_get */ 217 __RQ_EXP_BARR_ACK, 218 }; 219 220 #define RQ_LOCAL_PENDING (1UL << __RQ_LOCAL_PENDING) 221 #define RQ_LOCAL_COMPLETED (1UL << __RQ_LOCAL_COMPLETED) 222 #define RQ_LOCAL_OK (1UL << __RQ_LOCAL_OK) 223 #define RQ_LOCAL_ABORTED (1UL << __RQ_LOCAL_ABORTED) 224 225 #define RQ_LOCAL_MASK ((RQ_LOCAL_ABORTED << 1)-1) 226 227 #define RQ_NET_PENDING (1UL << __RQ_NET_PENDING) 228 #define RQ_NET_QUEUED (1UL << __RQ_NET_QUEUED) 229 #define RQ_NET_SENT (1UL << __RQ_NET_SENT) 230 #define RQ_NET_DONE (1UL << __RQ_NET_DONE) 231 #define RQ_NET_OK (1UL << __RQ_NET_OK) 232 #define RQ_NET_SIS (1UL << __RQ_NET_SIS) 233 234 /* 0x1f8 */ 235 #define RQ_NET_MASK (((1UL << __RQ_NET_MAX)-1) & ~RQ_LOCAL_MASK) 236 237 #define RQ_WRITE (1UL << __RQ_WRITE) 238 #define RQ_IN_ACT_LOG (1UL << __RQ_IN_ACT_LOG) 239 #define RQ_POSTPONED (1UL << __RQ_POSTPONED) 240 #define RQ_COMPLETION_SUSP (1UL << __RQ_COMPLETION_SUSP) 241 #define RQ_EXP_RECEIVE_ACK (1UL << __RQ_EXP_RECEIVE_ACK) 242 #define RQ_EXP_WRITE_ACK (1UL << __RQ_EXP_WRITE_ACK) 243 #define RQ_EXP_BARR_ACK (1UL << __RQ_EXP_BARR_ACK) 244 245 /* For waking up the frozen transfer log mod_req() has to return if the request 246 should be counted in the epoch object*/ 247 #define MR_WRITE 1 248 #define MR_READ 2 249 250 static inline void drbd_req_make_private_bio(struct drbd_request *req, struct bio *bio_src) 251 { 252 struct bio *bio; 253 bio = bio_clone(bio_src, GFP_NOIO); /* XXX cannot fail?? */ 254 255 req->private_bio = bio; 256 257 bio->bi_private = req; 258 bio->bi_end_io = drbd_request_endio; 259 bio->bi_next = NULL; 260 } 261 262 /* Short lived temporary struct on the stack. 263 * We could squirrel the error to be returned into 264 * bio->bi_size, or similar. But that would be too ugly. */ 265 struct bio_and_error { 266 struct bio *bio; 267 int error; 268 }; 269 270 extern void drbd_req_destroy(struct kref *kref); 271 extern void _req_may_be_done(struct drbd_request *req, 272 struct bio_and_error *m); 273 extern int __req_mod(struct drbd_request *req, enum drbd_req_event what, 274 struct bio_and_error *m); 275 extern void complete_master_bio(struct drbd_conf *mdev, 276 struct bio_and_error *m); 277 extern void request_timer_fn(unsigned long data); 278 extern void tl_restart(struct drbd_tconn *tconn, enum drbd_req_event what); 279 extern void _tl_restart(struct drbd_tconn *tconn, enum drbd_req_event what); 280 281 /* this is in drbd_main.c */ 282 extern void drbd_restart_request(struct drbd_request *req); 283 284 /* use this if you don't want to deal with calling complete_master_bio() 285 * outside the spinlock, e.g. when walking some list on cleanup. */ 286 static inline int _req_mod(struct drbd_request *req, enum drbd_req_event what) 287 { 288 struct drbd_conf *mdev = req->w.mdev; 289 struct bio_and_error m; 290 int rv; 291 292 /* __req_mod possibly frees req, do not touch req after that! */ 293 rv = __req_mod(req, what, &m); 294 if (m.bio) 295 complete_master_bio(mdev, &m); 296 297 return rv; 298 } 299 300 /* completion of master bio is outside of our spinlock. 301 * We still may or may not be inside some irqs disabled section 302 * of the lower level driver completion callback, so we need to 303 * spin_lock_irqsave here. */ 304 static inline int req_mod(struct drbd_request *req, 305 enum drbd_req_event what) 306 { 307 unsigned long flags; 308 struct drbd_conf *mdev = req->w.mdev; 309 struct bio_and_error m; 310 int rv; 311 312 spin_lock_irqsave(&mdev->tconn->req_lock, flags); 313 rv = __req_mod(req, what, &m); 314 spin_unlock_irqrestore(&mdev->tconn->req_lock, flags); 315 316 if (m.bio) 317 complete_master_bio(mdev, &m); 318 319 return rv; 320 } 321 322 static inline bool drbd_should_do_remote(union drbd_dev_state s) 323 { 324 return s.pdsk == D_UP_TO_DATE || 325 (s.pdsk >= D_INCONSISTENT && 326 s.conn >= C_WF_BITMAP_T && 327 s.conn < C_AHEAD); 328 /* Before proto 96 that was >= CONNECTED instead of >= C_WF_BITMAP_T. 329 That is equivalent since before 96 IO was frozen in the C_WF_BITMAP* 330 states. */ 331 } 332 static inline bool drbd_should_send_out_of_sync(union drbd_dev_state s) 333 { 334 return s.conn == C_AHEAD || s.conn == C_WF_BITMAP_S; 335 /* pdsk = D_INCONSISTENT as a consequence. Protocol 96 check not necessary 336 since we enter state C_AHEAD only if proto >= 96 */ 337 } 338 339 #endif 340