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1/* SPDX-License-Identifier: GPL-2.0-only */
2/*
3 drbd_req.h
4
5 This file is part of DRBD by Philipp Reisner and Lars Ellenberg.
6
7 Copyright (C) 2006-2008, LINBIT Information Technologies GmbH.
8 Copyright (C) 2006-2008, Lars Ellenberg <[email protected]>.
9 Copyright (C) 2006-2008, Philipp Reisner <[email protected]>.
10
11 */
12
13#ifndef _DRBD_REQ_H
14#define _DRBD_REQ_H
15
16#include <linux/module.h>
17
18#include <linux/slab.h>
19#include <linux/drbd.h>
20#include "drbd_int.h"
21
22/* The request callbacks will be called in irq context by the IDE drivers,
23 and in Softirqs/Tasklets/BH context by the SCSI drivers,
24 and by the receiver and worker in kernel-thread context.
25 Try to get the locking right :) */
26
27/*
28 * Objects of type struct drbd_request do only exist on a R_PRIMARY node, and are
29 * associated with IO requests originating from the block layer above us.
30 *
31 * There are quite a few things that may happen to a drbd request
32 * during its lifetime.
33 *
34 * It will be created.
35 * It will be marked with the intention to be
36 * submitted to local disk and/or
37 * send via the network.
38 *
39 * It has to be placed on the transfer log and other housekeeping lists,
40 * In case we have a network connection.
41 *
42 * It may be identified as a concurrent (write) request
43 * and be handled accordingly.
44 *
45 * It may me handed over to the local disk subsystem.
46 * It may be completed by the local disk subsystem,
47 * either successfully or with io-error.
48 * In case it is a READ request, and it failed locally,
49 * it may be retried remotely.
50 *
51 * It may be queued for sending.
52 * It may be handed over to the network stack,
53 * which may fail.
54 * It may be acknowledged by the "peer" according to the wire_protocol in use.
55 * this may be a negative ack.
56 * It may receive a faked ack when the network connection is lost and the
57 * transfer log is cleaned up.
58 * Sending may be canceled due to network connection loss.
59 * When it finally has outlived its time,
60 * corresponding dirty bits in the resync-bitmap may be cleared or set,
61 * it will be destroyed,
62 * and completion will be signalled to the originator,
63 * with or without "success".
64 */
65
66enum drbd_req_event {
67 CREATED,
68 TO_BE_SENT,
69 TO_BE_SUBMITTED,
70
71 /* XXX yes, now I am inconsistent...
72 * these are not "events" but "actions"
73 * oh, well... */
74 QUEUE_FOR_NET_WRITE,
75 QUEUE_FOR_NET_READ,
76 QUEUE_FOR_SEND_OOS,
77
78 /* An empty flush is queued as P_BARRIER,
79 * which will cause it to complete "successfully",
80 * even if the local disk flush failed.
81 *
82 * Just like "real" requests, empty flushes (blkdev_issue_flush()) will
83 * only see an error if neither local nor remote data is reachable. */
84 QUEUE_AS_DRBD_BARRIER,
85
86 SEND_CANCELED,
87 SEND_FAILED,
88 HANDED_OVER_TO_NETWORK,
89 OOS_HANDED_TO_NETWORK,
90 CONNECTION_LOST_WHILE_PENDING,
91 READ_RETRY_REMOTE_CANCELED,
92 RECV_ACKED_BY_PEER,
93 WRITE_ACKED_BY_PEER,
94 WRITE_ACKED_BY_PEER_AND_SIS, /* and set_in_sync */
95 CONFLICT_RESOLVED,
96 POSTPONE_WRITE,
97 NEG_ACKED,
98 BARRIER_ACKED, /* in protocol A and B */
99 DATA_RECEIVED, /* (remote read) */
100
101 COMPLETED_OK,
102 READ_COMPLETED_WITH_ERROR,
103 READ_AHEAD_COMPLETED_WITH_ERROR,
104 WRITE_COMPLETED_WITH_ERROR,
105 DISCARD_COMPLETED_NOTSUPP,
106 DISCARD_COMPLETED_WITH_ERROR,
107
108 ABORT_DISK_IO,
109 RESEND,
110 FAIL_FROZEN_DISK_IO,
111 RESTART_FROZEN_DISK_IO,
112 NOTHING,
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 /* 3210
122 * 0000: no local possible
123 * 0001: to be submitted
124 * UNUSED, we could map: 011: submitted, completion still pending
125 * 0110: completed ok
126 * 0010: completed with error
127 * 1001: Aborted (before completion)
128 * 1x10: Aborted and completed -> free
129 */
130 __RQ_LOCAL_PENDING,
131 __RQ_LOCAL_COMPLETED,
132 __RQ_LOCAL_OK,
133 __RQ_LOCAL_ABORTED,
134
135 /* 87654
136 * 00000: no network possible
137 * 00001: to be send
138 * 00011: to be send, on worker queue
139 * 00101: sent, expecting recv_ack (B) or write_ack (C)
140 * 11101: sent,
141 * recv_ack (B) or implicit "ack" (A),
142 * still waiting for the barrier ack.
143 * master_bio may already be completed and invalidated.
144 * 11100: write acked (C),
145 * data received (for remote read, any protocol)
146 * or finally the barrier ack has arrived (B,A)...
147 * request can be freed
148 * 01100: neg-acked (write, protocol C)
149 * or neg-d-acked (read, any protocol)
150 * or killed from the transfer log
151 * during cleanup after connection loss
152 * request can be freed
153 * 01000: canceled or send failed...
154 * request can be freed
155 */
156
157 /* if "SENT" is not set, yet, this can still fail or be canceled.
158 * if "SENT" is set already, we still wait for an Ack packet.
159 * when cleared, the master_bio may be completed.
160 * in (B,A) the request object may still linger on the transaction log
161 * until the corresponding barrier ack comes in */
162 __RQ_NET_PENDING,
163
164 /* If it is QUEUED, and it is a WRITE, it is also registered in the
165 * transfer log. Currently we need this flag to avoid conflicts between
166 * worker canceling the request and tl_clear_barrier killing it from
167 * transfer log. We should restructure the code so this conflict does
168 * no longer occur. */
169 __RQ_NET_QUEUED,
170
171 /* well, actually only "handed over to the network stack".
172 *
173 * TODO can potentially be dropped because of the similar meaning
174 * of RQ_NET_SENT and ~RQ_NET_QUEUED.
175 * however it is not exactly the same. before we drop it
176 * we must ensure that we can tell a request with network part
177 * from a request without, regardless of what happens to it. */
178 __RQ_NET_SENT,
179
180 /* when set, the request may be freed (if RQ_NET_QUEUED is clear).
181 * basically this means the corresponding P_BARRIER_ACK was received */
182 __RQ_NET_DONE,
183
184 /* whether or not we know (C) or pretend (B,A) that the write
185 * was successfully written on the peer.
186 */
187 __RQ_NET_OK,
188
189 /* peer called drbd_set_in_sync() for this write */
190 __RQ_NET_SIS,
191
192 /* keep this last, its for the RQ_NET_MASK */
193 __RQ_NET_MAX,
194
195 /* Set when this is a write, clear for a read */
196 __RQ_WRITE,
197 __RQ_WSAME,
198 __RQ_UNMAP,
199 __RQ_ZEROES,
200
201 /* Should call drbd_al_complete_io() for this request... */
202 __RQ_IN_ACT_LOG,
203
204 /* This was the most recent request during some blk_finish_plug()
205 * or its implicit from-schedule equivalent.
206 * We may use it as hint to send a P_UNPLUG_REMOTE */
207 __RQ_UNPLUG,
208
209 /* The peer has sent a retry ACK */
210 __RQ_POSTPONED,
211
212 /* would have been completed,
213 * but was not, because of drbd_suspended() */
214 __RQ_COMPLETION_SUSP,
215
216 /* We expect a receive ACK (wire proto B) */
217 __RQ_EXP_RECEIVE_ACK,
218
219 /* We expect a write ACK (wite proto C) */
220 __RQ_EXP_WRITE_ACK,
221
222 /* waiting for a barrier ack, did an extra kref_get */
223 __RQ_EXP_BARR_ACK,
224};
225
226#define RQ_LOCAL_PENDING (1UL << __RQ_LOCAL_PENDING)
227#define RQ_LOCAL_COMPLETED (1UL << __RQ_LOCAL_COMPLETED)
228#define RQ_LOCAL_OK (1UL << __RQ_LOCAL_OK)
229#define RQ_LOCAL_ABORTED (1UL << __RQ_LOCAL_ABORTED)
230
231#define RQ_LOCAL_MASK ((RQ_LOCAL_ABORTED << 1)-1)
232
233#define RQ_NET_PENDING (1UL << __RQ_NET_PENDING)
234#define RQ_NET_QUEUED (1UL << __RQ_NET_QUEUED)
235#define RQ_NET_SENT (1UL << __RQ_NET_SENT)
236#define RQ_NET_DONE (1UL << __RQ_NET_DONE)
237#define RQ_NET_OK (1UL << __RQ_NET_OK)
238#define RQ_NET_SIS (1UL << __RQ_NET_SIS)
239
240#define RQ_NET_MASK (((1UL << __RQ_NET_MAX)-1) & ~RQ_LOCAL_MASK)
241
242#define RQ_WRITE (1UL << __RQ_WRITE)
243#define RQ_WSAME (1UL << __RQ_WSAME)
244#define RQ_UNMAP (1UL << __RQ_UNMAP)
245#define RQ_ZEROES (1UL << __RQ_ZEROES)
246#define RQ_IN_ACT_LOG (1UL << __RQ_IN_ACT_LOG)
247#define RQ_UNPLUG (1UL << __RQ_UNPLUG)
248#define RQ_POSTPONED (1UL << __RQ_POSTPONED)
249#define RQ_COMPLETION_SUSP (1UL << __RQ_COMPLETION_SUSP)
250#define RQ_EXP_RECEIVE_ACK (1UL << __RQ_EXP_RECEIVE_ACK)
251#define RQ_EXP_WRITE_ACK (1UL << __RQ_EXP_WRITE_ACK)
252#define RQ_EXP_BARR_ACK (1UL << __RQ_EXP_BARR_ACK)
253
254/* For waking up the frozen transfer log mod_req() has to return if the request
255 should be counted in the epoch object*/
256#define MR_WRITE 1
257#define MR_READ 2
258
259/* Short lived temporary struct on the stack.
260 * We could squirrel the error to be returned into
261 * bio->bi_iter.bi_size, or similar. But that would be too ugly. */
262struct bio_and_error {
263 struct bio *bio;
264 int error;
265};
266
267extern void start_new_tl_epoch(struct drbd_connection *connection);
268extern void drbd_req_destroy(struct kref *kref);
269extern int __req_mod(struct drbd_request *req, enum drbd_req_event what,
270 struct drbd_peer_device *peer_device,
271 struct bio_and_error *m);
272extern void complete_master_bio(struct drbd_device *device,
273 struct bio_and_error *m);
274extern void request_timer_fn(struct timer_list *t);
275extern void tl_restart(struct drbd_connection *connection, enum drbd_req_event what);
276extern void _tl_restart(struct drbd_connection *connection, enum drbd_req_event what);
277extern void tl_abort_disk_io(struct drbd_device *device);
278
279/* this is in drbd_main.c */
280extern void drbd_restart_request(struct drbd_request *req);
281
282/* use this if you don't want to deal with calling complete_master_bio()
283 * outside the spinlock, e.g. when walking some list on cleanup. */
284static inline int _req_mod(struct drbd_request *req, enum drbd_req_event what,
285 struct drbd_peer_device *peer_device)
286{
287 struct drbd_device *device = req->device;
288 struct bio_and_error m;
289 int rv;
290
291 /* __req_mod possibly frees req, do not touch req after that! */
292 rv = __req_mod(req, what, peer_device, &m);
293 if (m.bio)
294 complete_master_bio(device, &m);
295
296 return rv;
297}
298
299/* completion of master bio is outside of our spinlock.
300 * We still may or may not be inside some irqs disabled section
301 * of the lower level driver completion callback, so we need to
302 * spin_lock_irqsave here. */
303static inline int req_mod(struct drbd_request *req,
304 enum drbd_req_event what,
305 struct drbd_peer_device *peer_device)
306{
307 unsigned long flags;
308 struct drbd_device *device = req->device;
309 struct bio_and_error m;
310 int rv;
311
312 spin_lock_irqsave(&device->resource->req_lock, flags);
313 rv = __req_mod(req, what, peer_device, &m);
314 spin_unlock_irqrestore(&device->resource->req_lock, flags);
315
316 if (m.bio)
317 complete_master_bio(device, &m);
318
319 return rv;
320}
321
322extern bool drbd_should_do_remote(union drbd_dev_state);
323
324#endif