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Philipp Reisnerb411b362009-09-25 16:07:19 -07001/*
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
Philipp Reisnerb411b362009-09-25 16:07:19 -070028#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,
Daniel Mack3ad2f3f2010-02-03 08:01:28 +080060 * either successfully or with io-error.
Philipp Reisnerb411b362009-09-25 16:07:19 -070061 * 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
79enum drbd_req_event {
80 created,
81 to_be_send,
82 to_be_submitted,
83
84 /* XXX yes, now I am inconsistent...
Philipp Reisner73a01a12010-10-27 14:33:00 +020085 * these are not "events" but "actions"
Philipp Reisnerb411b362009-09-25 16:07:19 -070086 * oh, well... */
87 queue_for_net_write,
88 queue_for_net_read,
Philipp Reisner73a01a12010-10-27 14:33:00 +020089 queue_for_send_oos,
Philipp Reisnerb411b362009-09-25 16:07:19 -070090
91 send_canceled,
92 send_failed,
93 handed_over_to_network,
Philipp Reisner73a01a12010-10-27 14:33:00 +020094 oos_handed_to_network,
Philipp Reisnerb411b362009-09-25 16:07:19 -070095 connection_lost_while_pending,
Lars Ellenbergd255e5f2010-05-27 09:45:45 +020096 read_retry_remote_canceled,
Philipp Reisnerb411b362009-09-25 16:07:19 -070097 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 completed_ok,
Philipp Reisner11b58e72010-05-12 17:08:26 +0200109 resend,
Philipp Reisner265be2d2010-05-31 10:14:17 +0200110 fail_frozen_disk_io,
111 restart_frozen_disk_io,
Philipp Reisnerb411b362009-09-25 16:07:19 -0700112 nothing, /* for tracing only */
113};
114
115/* encoding of request states for now. we don't actually need that many bits.
116 * we don't need to do atomic bit operations either, since most of the time we
117 * need to look at the connection state and/or manipulate some lists at the
118 * same time, so we should hold the request lock anyways.
119 */
120enum drbd_req_state_bits {
121 /* 210
122 * 000: no local possible
123 * 001: to be submitted
124 * UNUSED, we could map: 011: submitted, completion still pending
125 * 110: completed ok
126 * 010: completed with error
127 */
128 __RQ_LOCAL_PENDING,
129 __RQ_LOCAL_COMPLETED,
130 __RQ_LOCAL_OK,
131
132 /* 76543
133 * 00000: no network possible
134 * 00001: to be send
135 * 00011: to be send, on worker queue
136 * 00101: sent, expecting recv_ack (B) or write_ack (C)
137 * 11101: sent,
138 * recv_ack (B) or implicit "ack" (A),
139 * still waiting for the barrier ack.
140 * master_bio may already be completed and invalidated.
141 * 11100: write_acked (C),
142 * data_received (for remote read, any protocol)
143 * or finally the barrier ack has arrived (B,A)...
144 * request can be freed
145 * 01100: neg-acked (write, protocol C)
146 * or neg-d-acked (read, any protocol)
147 * or killed from the transfer log
148 * during cleanup after connection loss
149 * request can be freed
150 * 01000: canceled or send failed...
151 * request can be freed
152 */
153
154 /* if "SENT" is not set, yet, this can still fail or be canceled.
155 * if "SENT" is set already, we still wait for an Ack packet.
156 * when cleared, the master_bio may be completed.
157 * in (B,A) the request object may still linger on the transaction log
158 * until the corresponding barrier ack comes in */
159 __RQ_NET_PENDING,
160
161 /* If it is QUEUED, and it is a WRITE, it is also registered in the
162 * transfer log. Currently we need this flag to avoid conflicts between
163 * worker canceling the request and tl_clear_barrier killing it from
164 * transfer log. We should restructure the code so this conflict does
165 * no longer occur. */
166 __RQ_NET_QUEUED,
167
168 /* well, actually only "handed over to the network stack".
169 *
170 * TODO can potentially be dropped because of the similar meaning
171 * of RQ_NET_SENT and ~RQ_NET_QUEUED.
172 * however it is not exactly the same. before we drop it
173 * we must ensure that we can tell a request with network part
174 * from a request without, regardless of what happens to it. */
175 __RQ_NET_SENT,
176
177 /* when set, the request may be freed (if RQ_NET_QUEUED is clear).
178 * basically this means the corresponding P_BARRIER_ACK was received */
179 __RQ_NET_DONE,
180
181 /* whether or not we know (C) or pretend (B,A) that the write
182 * was successfully written on the peer.
183 */
184 __RQ_NET_OK,
185
186 /* peer called drbd_set_in_sync() for this write */
187 __RQ_NET_SIS,
188
189 /* keep this last, its for the RQ_NET_MASK */
190 __RQ_NET_MAX,
Philipp Reisner288f4222010-05-27 15:07:43 +0200191
192 /* Set when this is a write, clear for a read */
193 __RQ_WRITE,
Philipp Reisner07782862010-08-31 12:00:50 +0200194
195 /* Should call drbd_al_complete_io() for this request... */
196 __RQ_IN_ACT_LOG,
Philipp Reisnerb411b362009-09-25 16:07:19 -0700197};
198
199#define RQ_LOCAL_PENDING (1UL << __RQ_LOCAL_PENDING)
200#define RQ_LOCAL_COMPLETED (1UL << __RQ_LOCAL_COMPLETED)
201#define RQ_LOCAL_OK (1UL << __RQ_LOCAL_OK)
202
203#define RQ_LOCAL_MASK ((RQ_LOCAL_OK << 1)-1) /* 0x07 */
204
205#define RQ_NET_PENDING (1UL << __RQ_NET_PENDING)
206#define RQ_NET_QUEUED (1UL << __RQ_NET_QUEUED)
207#define RQ_NET_SENT (1UL << __RQ_NET_SENT)
208#define RQ_NET_DONE (1UL << __RQ_NET_DONE)
209#define RQ_NET_OK (1UL << __RQ_NET_OK)
210#define RQ_NET_SIS (1UL << __RQ_NET_SIS)
211
212/* 0x1f8 */
213#define RQ_NET_MASK (((1UL << __RQ_NET_MAX)-1) & ~RQ_LOCAL_MASK)
214
Philipp Reisner288f4222010-05-27 15:07:43 +0200215#define RQ_WRITE (1UL << __RQ_WRITE)
Philipp Reisner07782862010-08-31 12:00:50 +0200216#define RQ_IN_ACT_LOG (1UL << __RQ_IN_ACT_LOG)
Philipp Reisner288f4222010-05-27 15:07:43 +0200217
Philipp Reisner11b58e72010-05-12 17:08:26 +0200218/* For waking up the frozen transfer log mod_req() has to return if the request
219 should be counted in the epoch object*/
220#define MR_WRITE_SHIFT 0
221#define MR_WRITE (1 << MR_WRITE_SHIFT)
222#define MR_READ_SHIFT 1
223#define MR_READ (1 << MR_READ_SHIFT)
224
Philipp Reisnerb411b362009-09-25 16:07:19 -0700225/* epoch entries */
226static inline
227struct hlist_head *ee_hash_slot(struct drbd_conf *mdev, sector_t sector)
228{
229 BUG_ON(mdev->ee_hash_s == 0);
230 return mdev->ee_hash +
231 ((unsigned int)(sector>>HT_SHIFT) % mdev->ee_hash_s);
232}
233
234/* transfer log (drbd_request objects) */
235static inline
236struct hlist_head *tl_hash_slot(struct drbd_conf *mdev, sector_t sector)
237{
238 BUG_ON(mdev->tl_hash_s == 0);
239 return mdev->tl_hash +
240 ((unsigned int)(sector>>HT_SHIFT) % mdev->tl_hash_s);
241}
242
243/* application reads (drbd_request objects) */
244static struct hlist_head *ar_hash_slot(struct drbd_conf *mdev, sector_t sector)
245{
246 return mdev->app_reads_hash
247 + ((unsigned int)(sector) % APP_R_HSIZE);
248}
249
250/* when we receive the answer for a read request,
251 * verify that we actually know about it */
252static inline struct drbd_request *_ar_id_to_req(struct drbd_conf *mdev,
253 u64 id, sector_t sector)
254{
255 struct hlist_head *slot = ar_hash_slot(mdev, sector);
256 struct hlist_node *n;
257 struct drbd_request *req;
258
Bart Van Assche24c48302011-05-21 18:32:29 +0200259 hlist_for_each_entry(req, n, slot, collision) {
Philipp Reisnerb411b362009-09-25 16:07:19 -0700260 if ((unsigned long)req == (unsigned long)id) {
261 D_ASSERT(req->sector == sector);
262 return req;
263 }
264 }
265 return NULL;
266}
267
Philipp Reisner5ba82302010-06-10 13:30:36 +0200268static inline void drbd_req_make_private_bio(struct drbd_request *req, struct bio *bio_src)
269{
270 struct bio *bio;
271 bio = bio_clone(bio_src, GFP_NOIO); /* XXX cannot fail?? */
272
273 req->private_bio = bio;
274
275 bio->bi_private = req;
276 bio->bi_end_io = drbd_endio_pri;
277 bio->bi_next = NULL;
278}
279
Philipp Reisnerb411b362009-09-25 16:07:19 -0700280static inline struct drbd_request *drbd_req_new(struct drbd_conf *mdev,
281 struct bio *bio_src)
282{
Philipp Reisnerb411b362009-09-25 16:07:19 -0700283 struct drbd_request *req =
284 mempool_alloc(drbd_request_mempool, GFP_NOIO);
285 if (likely(req)) {
Philipp Reisner5ba82302010-06-10 13:30:36 +0200286 drbd_req_make_private_bio(req, bio_src);
Philipp Reisnerb411b362009-09-25 16:07:19 -0700287
Philipp Reisner288f4222010-05-27 15:07:43 +0200288 req->rq_state = bio_data_dir(bio_src) == WRITE ? RQ_WRITE : 0;
Philipp Reisnerb411b362009-09-25 16:07:19 -0700289 req->mdev = mdev;
290 req->master_bio = bio_src;
Philipp Reisnerb411b362009-09-25 16:07:19 -0700291 req->epoch = 0;
Philipp Reisner5ba82302010-06-10 13:30:36 +0200292 req->sector = bio_src->bi_sector;
293 req->size = bio_src->bi_size;
Bart Van Assche24c48302011-05-21 18:32:29 +0200294 INIT_HLIST_NODE(&req->collision);
Philipp Reisnerb411b362009-09-25 16:07:19 -0700295 INIT_LIST_HEAD(&req->tl_requests);
296 INIT_LIST_HEAD(&req->w.list);
Philipp Reisnerb411b362009-09-25 16:07:19 -0700297 }
298 return req;
299}
300
301static inline void drbd_req_free(struct drbd_request *req)
302{
303 mempool_free(req, drbd_request_mempool);
304}
305
306static inline int overlaps(sector_t s1, int l1, sector_t s2, int l2)
307{
308 return !((s1 + (l1>>9) <= s2) || (s1 >= s2 + (l2>>9)));
309}
310
311/* Short lived temporary struct on the stack.
312 * We could squirrel the error to be returned into
313 * bio->bi_size, or similar. But that would be too ugly. */
314struct bio_and_error {
315 struct bio *bio;
316 int error;
317};
318
319extern void _req_may_be_done(struct drbd_request *req,
320 struct bio_and_error *m);
Philipp Reisner2a806992010-06-09 14:07:43 +0200321extern int __req_mod(struct drbd_request *req, enum drbd_req_event what,
Philipp Reisnerb411b362009-09-25 16:07:19 -0700322 struct bio_and_error *m);
323extern void complete_master_bio(struct drbd_conf *mdev,
324 struct bio_and_error *m);
Philipp Reisner7fde2be2011-03-01 11:08:28 +0100325extern void request_timer_fn(unsigned long data);
Andrew Morton0ddf72b2011-05-23 15:29:32 -0700326extern void tl_restart(struct drbd_conf *mdev, enum drbd_req_event what);
Philipp Reisnerb411b362009-09-25 16:07:19 -0700327
328/* use this if you don't want to deal with calling complete_master_bio()
329 * outside the spinlock, e.g. when walking some list on cleanup. */
Philipp Reisner2a806992010-06-09 14:07:43 +0200330static inline int _req_mod(struct drbd_request *req, enum drbd_req_event what)
Philipp Reisnerb411b362009-09-25 16:07:19 -0700331{
332 struct drbd_conf *mdev = req->mdev;
333 struct bio_and_error m;
Philipp Reisner2a806992010-06-09 14:07:43 +0200334 int rv;
Philipp Reisnerb411b362009-09-25 16:07:19 -0700335
336 /* __req_mod possibly frees req, do not touch req after that! */
Philipp Reisner2a806992010-06-09 14:07:43 +0200337 rv = __req_mod(req, what, &m);
Philipp Reisnerb411b362009-09-25 16:07:19 -0700338 if (m.bio)
339 complete_master_bio(mdev, &m);
Philipp Reisner2a806992010-06-09 14:07:43 +0200340
341 return rv;
Philipp Reisnerb411b362009-09-25 16:07:19 -0700342}
343
Philipp Reisner759fbdf2010-10-26 16:02:27 +0200344/* completion of master bio is outside of our spinlock.
345 * We still may or may not be inside some irqs disabled section
346 * of the lower level driver completion callback, so we need to
347 * spin_lock_irqsave here. */
Philipp Reisner2a806992010-06-09 14:07:43 +0200348static inline int req_mod(struct drbd_request *req,
Philipp Reisnerb411b362009-09-25 16:07:19 -0700349 enum drbd_req_event what)
350{
Philipp Reisner759fbdf2010-10-26 16:02:27 +0200351 unsigned long flags;
Philipp Reisnerb411b362009-09-25 16:07:19 -0700352 struct drbd_conf *mdev = req->mdev;
353 struct bio_and_error m;
Philipp Reisner2a806992010-06-09 14:07:43 +0200354 int rv;
355
Philipp Reisner759fbdf2010-10-26 16:02:27 +0200356 spin_lock_irqsave(&mdev->req_lock, flags);
Philipp Reisner2a806992010-06-09 14:07:43 +0200357 rv = __req_mod(req, what, &m);
Philipp Reisner759fbdf2010-10-26 16:02:27 +0200358 spin_unlock_irqrestore(&mdev->req_lock, flags);
Philipp Reisnerb411b362009-09-25 16:07:19 -0700359
360 if (m.bio)
361 complete_master_bio(mdev, &m);
Philipp Reisner2a806992010-06-09 14:07:43 +0200362
363 return rv;
Philipp Reisnerb411b362009-09-25 16:07:19 -0700364}
Philipp Reisner6a35c452011-01-17 20:27:30 +0100365
366static inline bool drbd_should_do_remote(union drbd_state s)
367{
368 return s.pdsk == D_UP_TO_DATE ||
369 (s.pdsk >= D_INCONSISTENT &&
370 s.conn >= C_WF_BITMAP_T &&
371 s.conn < C_AHEAD);
372 /* Before proto 96 that was >= CONNECTED instead of >= C_WF_BITMAP_T.
373 That is equivalent since before 96 IO was frozen in the C_WF_BITMAP*
374 states. */
375}
376static inline bool drbd_should_send_oos(union drbd_state s)
377{
378 return s.conn == C_AHEAD || s.conn == C_WF_BITMAP_S;
379 /* pdsk = D_INCONSISTENT as a consequence. Protocol 96 check not necessary
380 since we enter state C_AHEAD only if proto >= 96 */
381}
382
Philipp Reisnerb411b362009-09-25 16:07:19 -0700383#endif