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