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
drbd_req_make_private_bio(struct drbd_request * req,struct bio * bio_src)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. */
_req_mod(struct drbd_request * req,enum drbd_req_event what)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. */
req_mod(struct drbd_request * req,enum drbd_req_event what)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