drivers/block/drbd/drbd_req.h

   1 /* SPDX-License-Identifier: GPL-2.0-or-later */
   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 <lars.ellenberg@linbit.com>.
   9    Copyright (C) 2006-2008, Philipp Reisner <philipp.reisner@linbit.com>.
  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
  66 enum 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  */
 120 enum 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 static inline void drbd_req_make_private_bio(struct drbd_request *req, struct bio *bio_src)
 260 {
 261         struct bio *bio;
 262         bio = bio_clone_fast(bio_src, GFP_NOIO, &drbd_io_bio_set);
 263
 264         req->private_bio = bio;
 265
 266         bio->bi_private  = req;
 267         bio->bi_end_io   = drbd_request_endio;
 268         bio->bi_next     = NULL;
 269 }
 270
 271 /* Short lived temporary struct on the stack.
 272  * We could squirrel the error to be returned into
 273  * bio->bi_iter.bi_size, or similar. But that would be too ugly. */
 274 struct bio_and_error {
 275         struct bio *bio;
 276         int error;
 277 };
 278
 279 extern void start_new_tl_epoch(struct drbd_connection *connection);
 280 extern void drbd_req_destroy(struct kref *kref);
 281 extern void _req_may_be_done(struct drbd_request *req,
 282                 struct bio_and_error *m);
 283 extern int __req_mod(struct drbd_request *req, enum drbd_req_event what,
 284                 struct bio_and_error *m);
 285 extern void complete_master_bio(struct drbd_device *device,
 286                 struct bio_and_error *m);
 287 extern void request_timer_fn(struct timer_list *t);
 288 extern void tl_restart(struct drbd_connection *connection, enum drbd_req_event what);
 289 extern void _tl_restart(struct drbd_connection *connection, enum drbd_req_event what);
 290 extern void tl_abort_disk_io(struct drbd_device *device);
 291
 292 /* this is in drbd_main.c */
 293 extern void drbd_restart_request(struct drbd_request *req);
 294
 295 /* use this if you don't want to deal with calling complete_master_bio()
 296  * outside the spinlock, e.g. when walking some list on cleanup. */
 297 static inline int _req_mod(struct drbd_request *req, enum drbd_req_event what)
 298 {
 299         struct drbd_device *device = req->device;
 300         struct bio_and_error m;
 301         int rv;
 302
 303         /* __req_mod possibly frees req, do not touch req after that! */
 304         rv = __req_mod(req, what, &m);
 305         if (m.bio)
 306                 complete_master_bio(device, &m);
 307
 308         return rv;
 309 }
 310
 311 /* completion of master bio is outside of our spinlock.
 312  * We still may or may not be inside some irqs disabled section
 313  * of the lower level driver completion callback, so we need to
 314  * spin_lock_irqsave here. */
 315 static inline int req_mod(struct drbd_request *req,
 316                 enum drbd_req_event what)
 317 {
 318         unsigned long flags;
 319         struct drbd_device *device = req->device;
 320         struct bio_and_error m;
 321         int rv;
 322
 323         spin_lock_irqsave(&device->resource->req_lock, flags);
 324         rv = __req_mod(req, what, &m);
 325         spin_unlock_irqrestore(&device->resource->req_lock, flags);
 326
 327         if (m.bio)
 328                 complete_master_bio(device, &m);
 329
 330         return rv;
 331 }
 332
 333 extern bool drbd_should_do_remote(union drbd_dev_state);
 334
 335 #endif