xref: /openbmc/linux/drivers/block/drbd/drbd_req.h (revision 0edbfea5)
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 
210 	/* Should call drbd_al_complete_io() for this request... */
211 	__RQ_IN_ACT_LOG,
212 
213 	/* The peer has sent a retry ACK */
214 	__RQ_POSTPONED,
215 
216 	/* would have been completed,
217 	 * but was not, because of drbd_suspended() */
218 	__RQ_COMPLETION_SUSP,
219 
220 	/* We expect a receive ACK (wire proto B) */
221 	__RQ_EXP_RECEIVE_ACK,
222 
223 	/* We expect a write ACK (wite proto C) */
224 	__RQ_EXP_WRITE_ACK,
225 
226 	/* waiting for a barrier ack, did an extra kref_get */
227 	__RQ_EXP_BARR_ACK,
228 };
229 
230 #define RQ_LOCAL_PENDING   (1UL << __RQ_LOCAL_PENDING)
231 #define RQ_LOCAL_COMPLETED (1UL << __RQ_LOCAL_COMPLETED)
232 #define RQ_LOCAL_OK        (1UL << __RQ_LOCAL_OK)
233 #define RQ_LOCAL_ABORTED   (1UL << __RQ_LOCAL_ABORTED)
234 
235 #define RQ_LOCAL_MASK      ((RQ_LOCAL_ABORTED << 1)-1)
236 
237 #define RQ_NET_PENDING     (1UL << __RQ_NET_PENDING)
238 #define RQ_NET_QUEUED      (1UL << __RQ_NET_QUEUED)
239 #define RQ_NET_SENT        (1UL << __RQ_NET_SENT)
240 #define RQ_NET_DONE        (1UL << __RQ_NET_DONE)
241 #define RQ_NET_OK          (1UL << __RQ_NET_OK)
242 #define RQ_NET_SIS         (1UL << __RQ_NET_SIS)
243 
244 /* 0x1f8 */
245 #define RQ_NET_MASK        (((1UL << __RQ_NET_MAX)-1) & ~RQ_LOCAL_MASK)
246 
247 #define RQ_WRITE           (1UL << __RQ_WRITE)
248 #define RQ_IN_ACT_LOG      (1UL << __RQ_IN_ACT_LOG)
249 #define RQ_POSTPONED	   (1UL << __RQ_POSTPONED)
250 #define RQ_COMPLETION_SUSP (1UL << __RQ_COMPLETION_SUSP)
251 #define RQ_EXP_RECEIVE_ACK (1UL << __RQ_EXP_RECEIVE_ACK)
252 #define RQ_EXP_WRITE_ACK   (1UL << __RQ_EXP_WRITE_ACK)
253 #define RQ_EXP_BARR_ACK    (1UL << __RQ_EXP_BARR_ACK)
254 
255 /* For waking up the frozen transfer log mod_req() has to return if the request
256    should be counted in the epoch object*/
257 #define MR_WRITE       1
258 #define MR_READ        2
259 
260 static inline void drbd_req_make_private_bio(struct drbd_request *req, struct bio *bio_src)
261 {
262 	struct bio *bio;
263 	bio = bio_clone(bio_src, GFP_NOIO); /* XXX cannot fail?? */
264 
265 	req->private_bio = bio;
266 
267 	bio->bi_private  = req;
268 	bio->bi_end_io   = drbd_request_endio;
269 	bio->bi_next     = NULL;
270 }
271 
272 /* Short lived temporary struct on the stack.
273  * We could squirrel the error to be returned into
274  * bio->bi_iter.bi_size, or similar. But that would be too ugly. */
275 struct bio_and_error {
276 	struct bio *bio;
277 	int error;
278 };
279 
280 extern void start_new_tl_epoch(struct drbd_connection *connection);
281 extern void drbd_req_destroy(struct kref *kref);
282 extern void _req_may_be_done(struct drbd_request *req,
283 		struct bio_and_error *m);
284 extern int __req_mod(struct drbd_request *req, enum drbd_req_event what,
285 		struct bio_and_error *m);
286 extern void complete_master_bio(struct drbd_device *device,
287 		struct bio_and_error *m);
288 extern void request_timer_fn(unsigned long data);
289 extern void tl_restart(struct drbd_connection *connection, enum drbd_req_event what);
290 extern void _tl_restart(struct drbd_connection *connection, enum drbd_req_event what);
291 extern void tl_abort_disk_io(struct drbd_device *device);
292 
293 /* this is in drbd_main.c */
294 extern void drbd_restart_request(struct drbd_request *req);
295 
296 /* use this if you don't want to deal with calling complete_master_bio()
297  * outside the spinlock, e.g. when walking some list on cleanup. */
298 static inline int _req_mod(struct drbd_request *req, enum drbd_req_event what)
299 {
300 	struct drbd_device *device = req->device;
301 	struct bio_and_error m;
302 	int rv;
303 
304 	/* __req_mod possibly frees req, do not touch req after that! */
305 	rv = __req_mod(req, what, &m);
306 	if (m.bio)
307 		complete_master_bio(device, &m);
308 
309 	return rv;
310 }
311 
312 /* completion of master bio is outside of our spinlock.
313  * We still may or may not be inside some irqs disabled section
314  * of the lower level driver completion callback, so we need to
315  * spin_lock_irqsave here. */
316 static inline int req_mod(struct drbd_request *req,
317 		enum drbd_req_event what)
318 {
319 	unsigned long flags;
320 	struct drbd_device *device = req->device;
321 	struct bio_and_error m;
322 	int rv;
323 
324 	spin_lock_irqsave(&device->resource->req_lock, flags);
325 	rv = __req_mod(req, what, &m);
326 	spin_unlock_irqrestore(&device->resource->req_lock, flags);
327 
328 	if (m.bio)
329 		complete_master_bio(device, &m);
330 
331 	return rv;
332 }
333 
334 extern bool drbd_should_do_remote(union drbd_dev_state);
335 
336 #endif
337