drivers/block/nbd.c

   1 /*
   2  * Network block device - make block devices work over TCP
   3  *
   4  * Note that you can not swap over this thing, yet. Seems to work but
   5  * deadlocks sometimes - you can not swap over TCP in general.
   6  *
   7  * Copyright 1997-2000, 2008 Pavel Machek <pavel@ucw.cz>
   8  * Parts copyright 2001 Steven Whitehouse <steve@chygwyn.com>
   9  *
  10  * This file is released under GPLv2 or later.
  11  *
  12  * (part of code stolen from loop.c)
  13  */
  14
  15 #include <linux/major.h>
  16
  17 #include <linux/blkdev.h>
  18 #include <linux/module.h>
  19 #include <linux/init.h>
  20 #include <linux/sched.h>
  21 #include <linux/sched/mm.h>
  22 #include <linux/fs.h>
  23 #include <linux/bio.h>
  24 #include <linux/stat.h>
  25 #include <linux/errno.h>
  26 #include <linux/file.h>
  27 #include <linux/ioctl.h>
  28 #include <linux/mutex.h>
  29 #include <linux/compiler.h>
  30 #include <linux/err.h>
  31 #include <linux/kernel.h>
  32 #include <linux/slab.h>
  33 #include <net/sock.h>
  34 #include <linux/net.h>
  35 #include <linux/kthread.h>
  36 #include <linux/types.h>
  37 #include <linux/debugfs.h>
  38 #include <linux/blk-mq.h>
  39
  40 #include <linux/uaccess.h>
  41 #include <asm/types.h>
  42
  43 #include <linux/nbd.h>
  44 #include <linux/nbd-netlink.h>
  45 #include <net/genetlink.h>
  46
  47 static DEFINE_IDR(nbd_index_idr);
  48 static DEFINE_MUTEX(nbd_index_mutex);
  49 static int nbd_total_devices = 0;
  50
  51 struct nbd_sock {
  52         struct socket *sock;
  53         struct mutex tx_lock;
  54         struct request *pending;
  55         int sent;
  56         bool dead;
  57         int fallback_index;
  58         int cookie;
  59 };
  60
  61 struct recv_thread_args {
  62         struct work_struct work;
  63         struct nbd_device *nbd;
  64         int index;
  65 };
  66
  67 struct link_dead_args {
  68         struct work_struct work;
  69         int index;
  70 };
  71
  72 #define NBD_TIMEDOUT                    0
  73 #define NBD_DISCONNECT_REQUESTED        1
  74 #define NBD_DISCONNECTED                2
  75 #define NBD_HAS_PID_FILE                3
  76 #define NBD_HAS_CONFIG_REF              4
  77 #define NBD_BOUND                       5
  78 #define NBD_DESTROY_ON_DISCONNECT       6
  79
  80 struct nbd_config {
  81         u32 flags;
  82         unsigned long runtime_flags;
  83         u64 dead_conn_timeout;
  84
  85         struct nbd_sock **socks;
  86         int num_connections;
  87         atomic_t live_connections;
  88         wait_queue_head_t conn_wait;
  89
  90         atomic_t recv_threads;
  91         wait_queue_head_t recv_wq;
  92         loff_t blksize;
  93         loff_t bytesize;
  94 #if IS_ENABLED(CONFIG_DEBUG_FS)
  95         struct dentry *dbg_dir;
  96 #endif
  97 };
  98
  99 struct nbd_device {
 100         struct blk_mq_tag_set tag_set;
 101
 102         int index;
 103         refcount_t config_refs;
 104         refcount_t refs;
 105         struct nbd_config *config;
 106         struct mutex config_lock;
 107         struct gendisk *disk;
 108
 109         struct list_head list;
 110         struct task_struct *task_recv;
 111         struct task_struct *task_setup;
 112 };
 113
 114 struct nbd_cmd {
 115         struct nbd_device *nbd;
 116         int index;
 117         int cookie;
 118         struct completion send_complete;
 119         blk_status_t status;
 120 };
 121
 122 #if IS_ENABLED(CONFIG_DEBUG_FS)
 123 static struct dentry *nbd_dbg_dir;
 124 #endif
 125
 126 #define nbd_name(nbd) ((nbd)->disk->disk_name)
 127
 128 #define NBD_MAGIC 0x68797548
 129
 130 static unsigned int nbds_max = 16;
 131 static int max_part = 16;
 132 static struct workqueue_struct *recv_workqueue;
 133 static int part_shift;
 134
 135 static int nbd_dev_dbg_init(struct nbd_device *nbd);
 136 static void nbd_dev_dbg_close(struct nbd_device *nbd);
 137 static void nbd_config_put(struct nbd_device *nbd);
 138 static void nbd_connect_reply(struct genl_info *info, int index);
 139 static int nbd_genl_status(struct sk_buff *skb, struct genl_info *info);
 140 static void nbd_dead_link_work(struct work_struct *work);
 141
 142 static inline struct device *nbd_to_dev(struct nbd_device *nbd)
 143 {
 144         return disk_to_dev(nbd->disk);
 145 }
 146
 147 static const char *nbdcmd_to_ascii(int cmd)
 148 {
 149         switch (cmd) {
 150         case  NBD_CMD_READ: return "read";
 151         case NBD_CMD_WRITE: return "write";
 152         case  NBD_CMD_DISC: return "disconnect";
 153         case NBD_CMD_FLUSH: return "flush";
 154         case  NBD_CMD_TRIM: return "trim/discard";
 155         }
 156         return "invalid";
 157 }
 158
 159 static ssize_t pid_show(struct device *dev,
 160                         struct device_attribute *attr, char *buf)
 161 {
 162         struct gendisk *disk = dev_to_disk(dev);
 163         struct nbd_device *nbd = (struct nbd_device *)disk->private_data;
 164
 165         return sprintf(buf, "%d\n", task_pid_nr(nbd->task_recv));
 166 }
 167
 168 static const struct device_attribute pid_attr = {
 169         .attr = { .name = "pid", .mode = S_IRUGO},
 170         .show = pid_show,
 171 };
 172
 173 static void nbd_dev_remove(struct nbd_device *nbd)
 174 {
 175         struct gendisk *disk = nbd->disk;
 176         if (disk) {
 177                 del_gendisk(disk);
 178                 blk_cleanup_queue(disk->queue);
 179                 blk_mq_free_tag_set(&nbd->tag_set);
 180                 disk->private_data = NULL;
 181                 put_disk(disk);
 182         }
 183         kfree(nbd);
 184 }
 185
 186 static void nbd_put(struct nbd_device *nbd)
 187 {
 188         if (refcount_dec_and_mutex_lock(&nbd->refs,
 189                                         &nbd_index_mutex)) {
 190                 idr_remove(&nbd_index_idr, nbd->index);
 191                 mutex_unlock(&nbd_index_mutex);
 192                 nbd_dev_remove(nbd);
 193         }
 194 }
 195
 196 static int nbd_disconnected(struct nbd_config *config)
 197 {
 198         return test_bit(NBD_DISCONNECTED, &config->runtime_flags) ||
 199                 test_bit(NBD_DISCONNECT_REQUESTED, &config->runtime_flags);
 200 }
 201
 202 static void nbd_mark_nsock_dead(struct nbd_device *nbd, struct nbd_sock *nsock,
 203                                 int notify)
 204 {
 205         if (!nsock->dead && notify && !nbd_disconnected(nbd->config)) {
 206                 struct link_dead_args *args;
 207                 args = kmalloc(sizeof(struct link_dead_args), GFP_NOIO);
 208                 if (args) {
 209                         INIT_WORK(&args->work, nbd_dead_link_work);
 210                         args->index = nbd->index;
 211                         queue_work(system_wq, &args->work);
 212                 }
 213         }
 214         if (!nsock->dead) {
 215                 kernel_sock_shutdown(nsock->sock, SHUT_RDWR);
 216                 atomic_dec(&nbd->config->live_connections);
 217         }
 218         nsock->dead = true;
 219         nsock->pending = NULL;
 220         nsock->sent = 0;
 221 }
 222
 223 static void nbd_size_clear(struct nbd_device *nbd)
 224 {
 225         if (nbd->config->bytesize) {
 226                 set_capacity(nbd->disk, 0);
 227                 kobject_uevent(&nbd_to_dev(nbd)->kobj, KOBJ_CHANGE);
 228         }
 229 }
 230
 231 static void nbd_size_update(struct nbd_device *nbd)
 232 {
 233         struct nbd_config *config = nbd->config;
 234         blk_queue_logical_block_size(nbd->disk->queue, config->blksize);
 235         blk_queue_physical_block_size(nbd->disk->queue, config->blksize);
 236         set_capacity(nbd->disk, config->bytesize >> 9);
 237         kobject_uevent(&nbd_to_dev(nbd)->kobj, KOBJ_CHANGE);
 238 }
 239
 240 static void nbd_size_set(struct nbd_device *nbd, loff_t blocksize,
 241                          loff_t nr_blocks)
 242 {
 243         struct nbd_config *config = nbd->config;
 244         config->blksize = blocksize;
 245         config->bytesize = blocksize * nr_blocks;
 246 }
 247
 248 static void nbd_complete_rq(struct request *req)
 249 {
 250         struct nbd_cmd *cmd = blk_mq_rq_to_pdu(req);
 251
 252         dev_dbg(nbd_to_dev(cmd->nbd), "request %p: %s\n", cmd,
 253                 cmd->status ? "failed" : "done");
 254
 255         blk_mq_end_request(req, cmd->status);
 256 }
 257
 258 /*
 259  * Forcibly shutdown the socket causing all listeners to error
 260  */
 261 static void sock_shutdown(struct nbd_device *nbd)
 262 {
 263         struct nbd_config *config = nbd->config;
 264         int i;
 265
 266         if (config->num_connections == 0)
 267                 return;
 268         if (test_and_set_bit(NBD_DISCONNECTED, &config->runtime_flags))
 269                 return;
 270
 271         for (i = 0; i < config->num_connections; i++) {
 272                 struct nbd_sock *nsock = config->socks[i];
 273                 mutex_lock(&nsock->tx_lock);
 274                 nbd_mark_nsock_dead(nbd, nsock, 0);
 275                 mutex_unlock(&nsock->tx_lock);
 276         }
 277         dev_warn(disk_to_dev(nbd->disk), "shutting down sockets\n");
 278 }
 279
 280 static enum blk_eh_timer_return nbd_xmit_timeout(struct request *req,
 281                                                  bool reserved)
 282 {
 283         struct nbd_cmd *cmd = blk_mq_rq_to_pdu(req);
 284         struct nbd_device *nbd = cmd->nbd;
 285         struct nbd_config *config;
 286
 287         if (!refcount_inc_not_zero(&nbd->config_refs)) {
 288                 cmd->status = BLK_STS_TIMEOUT;
 289                 return BLK_EH_HANDLED;
 290         }
 291         config = nbd->config;
 292
 293         if (config->num_connections > 1) {
 294                 dev_err_ratelimited(nbd_to_dev(nbd),
 295                                     "Connection timed out, retrying\n");
 296                 /*
 297                  * Hooray we have more connections, requeue this IO, the submit
 298                  * path will put it on a real connection.
 299                  */
 300                 if (config->socks && config->num_connections > 1) {
 301                         if (cmd->index < config->num_connections) {
 302                                 struct nbd_sock *nsock =
 303                                         config->socks[cmd->index];
 304                                 mutex_lock(&nsock->tx_lock);
 305                                 /* We can have multiple outstanding requests, so
 306                                  * we don't want to mark the nsock dead if we've
 307                                  * already reconnected with a new socket, so
 308                                  * only mark it dead if its the same socket we
 309                                  * were sent out on.
 310                                  */
 311                                 if (cmd->cookie == nsock->cookie)
 312                                         nbd_mark_nsock_dead(nbd, nsock, 1);
 313                                 mutex_unlock(&nsock->tx_lock);
 314                         }
 315                         blk_mq_requeue_request(req, true);
 316                         nbd_config_put(nbd);
 317                         return BLK_EH_NOT_HANDLED;
 318                 }
 319         } else {
 320                 dev_err_ratelimited(nbd_to_dev(nbd),
 321                                     "Connection timed out\n");
 322         }
 323         set_bit(NBD_TIMEDOUT, &config->runtime_flags);
 324         cmd->status = BLK_STS_IOERR;
 325         sock_shutdown(nbd);
 326         nbd_config_put(nbd);
 327
 328         return BLK_EH_HANDLED;
 329 }
 330
 331 /*
 332  *  Send or receive packet.
 333  */
 334 static int sock_xmit(struct nbd_device *nbd, int index, int send,
 335                      struct iov_iter *iter, int msg_flags, int *sent)
 336 {
 337         struct nbd_config *config = nbd->config;
 338         struct socket *sock = config->socks[index]->sock;
 339         int result;
 340         struct msghdr msg;
 341         unsigned int noreclaim_flag;
 342
 343         if (unlikely(!sock)) {
 344                 dev_err_ratelimited(disk_to_dev(nbd->disk),
 345                         "Attempted %s on closed socket in sock_xmit\n",
 346                         (send ? "send" : "recv"));
 347                 return -EINVAL;
 348         }
 349
 350         msg.msg_iter = *iter;
 351
 352         noreclaim_flag = memalloc_noreclaim_save();
 353         do {
 354                 sock->sk->sk_allocation = GFP_NOIO | __GFP_MEMALLOC;
 355                 msg.msg_name = NULL;
 356                 msg.msg_namelen = 0;
 357                 msg.msg_control = NULL;
 358                 msg.msg_controllen = 0;
 359                 msg.msg_flags = msg_flags | MSG_NOSIGNAL;
 360
 361                 if (send)
 362                         result = sock_sendmsg(sock, &msg);
 363                 else
 364                         result = sock_recvmsg(sock, &msg, msg.msg_flags);
 365
 366                 if (result <= 0) {
 367                         if (result == 0)
 368                                 result = -EPIPE; /* short read */
 369                         break;
 370                 }
 371                 if (sent)
 372                         *sent += result;
 373         } while (msg_data_left(&msg));
 374
 375         memalloc_noreclaim_restore(noreclaim_flag);
 376
 377         return result;
 378 }
 379
 380 /*
 381  * Different settings for sk->sk_sndtimeo can result in different return values
 382  * if there is a signal pending when we enter sendmsg, because reasons?
 383  */
 384 static inline int was_interrupted(int result)
 385 {
 386         return result == -ERESTARTSYS || result == -EINTR;
 387 }
 388
 389 /* always call with the tx_lock held */
 390 static int nbd_send_cmd(struct nbd_device *nbd, struct nbd_cmd *cmd, int index)
 391 {
 392         struct request *req = blk_mq_rq_from_pdu(cmd);
 393         struct nbd_config *config = nbd->config;
 394         struct nbd_sock *nsock = config->socks[index];
 395         int result;
 396         struct nbd_request request = {.magic = htonl(NBD_REQUEST_MAGIC)};
 397         struct kvec iov = {.iov_base = &request, .iov_len = sizeof(request)};
 398         struct iov_iter from;
 399         unsigned long size = blk_rq_bytes(req);
 400         struct bio *bio;
 401         u32 type;
 402         u32 nbd_cmd_flags = 0;
 403         u32 tag = blk_mq_unique_tag(req);
 404         int sent = nsock->sent, skip = 0;
 405
 406         iov_iter_kvec(&from, WRITE | ITER_KVEC, &iov, 1, sizeof(request));
 407
 408         switch (req_op(req)) {
 409         case REQ_OP_DISCARD:
 410                 type = NBD_CMD_TRIM;
 411                 break;
 412         case REQ_OP_FLUSH:
 413                 type = NBD_CMD_FLUSH;
 414                 break;
 415         case REQ_OP_WRITE:
 416                 type = NBD_CMD_WRITE;
 417                 break;
 418         case REQ_OP_READ:
 419                 type = NBD_CMD_READ;
 420                 break;
 421         default:
 422                 return -EIO;
 423         }
 424
 425         if (rq_data_dir(req) == WRITE &&
 426             (config->flags & NBD_FLAG_READ_ONLY)) {
 427                 dev_err_ratelimited(disk_to_dev(nbd->disk),
 428                                     "Write on read-only\n");
 429                 return -EIO;
 430         }
 431
 432         if (req->cmd_flags & REQ_FUA)
 433                 nbd_cmd_flags |= NBD_CMD_FLAG_FUA;
 434
 435         /* We did a partial send previously, and we at least sent the whole
 436          * request struct, so just go and send the rest of the pages in the
 437          * request.
 438          */
 439         if (sent) {
 440                 if (sent >= sizeof(request)) {
 441                         skip = sent - sizeof(request);
 442                         goto send_pages;
 443                 }
 444                 iov_iter_advance(&from, sent);
 445         }
 446         cmd->index = index;
 447         cmd->cookie = nsock->cookie;
 448         request.type = htonl(type | nbd_cmd_flags);
 449         if (type != NBD_CMD_FLUSH) {
 450                 request.from = cpu_to_be64((u64)blk_rq_pos(req) << 9);
 451                 request.len = htonl(size);
 452         }
 453         memcpy(request.handle, &tag, sizeof(tag));
 454
 455         dev_dbg(nbd_to_dev(nbd), "request %p: sending control (%s@%llu,%uB)\n",
 456                 cmd, nbdcmd_to_ascii(type),
 457                 (unsigned long long)blk_rq_pos(req) << 9, blk_rq_bytes(req));
 458         result = sock_xmit(nbd, index, 1, &from,
 459                         (type == NBD_CMD_WRITE) ? MSG_MORE : 0, &sent);
 460         if (result <= 0) {
 461                 if (was_interrupted(result)) {
 462                         /* If we havne't sent anything we can just return BUSY,
 463                          * however if we have sent something we need to make
 464                          * sure we only allow this req to be sent until we are
 465                          * completely done.
 466                          */
 467                         if (sent) {
 468                                 nsock->pending = req;
 469                                 nsock->sent = sent;
 470                         }
 471                         return BLK_STS_RESOURCE;
 472                 }
 473                 dev_err_ratelimited(disk_to_dev(nbd->disk),
 474                         "Send control failed (result %d)\n", result);
 475                 return -EAGAIN;
 476         }
 477 send_pages:
 478         if (type != NBD_CMD_WRITE)
 479                 goto out;
 480
 481         bio = req->bio;
 482         while (bio) {
 483                 struct bio *next = bio->bi_next;
 484                 struct bvec_iter iter;
 485                 struct bio_vec bvec;
 486
 487                 bio_for_each_segment(bvec, bio, iter) {
 488                         bool is_last = !next && bio_iter_last(bvec, iter);
 489                         int flags = is_last ? 0 : MSG_MORE;
 490
 491                         dev_dbg(nbd_to_dev(nbd), "request %p: sending %d bytes data\n",
 492                                 cmd, bvec.bv_len);
 493                         iov_iter_bvec(&from, ITER_BVEC | WRITE,
 494                                       &bvec, 1, bvec.bv_len);
 495                         if (skip) {
 496                                 if (skip >= iov_iter_count(&from)) {
 497                                         skip -= iov_iter_count(&from);
 498                                         continue;
 499                                 }
 500                                 iov_iter_advance(&from, skip);
 501                                 skip = 0;
 502                         }
 503                         result = sock_xmit(nbd, index, 1, &from, flags, &sent);
 504                         if (result <= 0) {
 505                                 if (was_interrupted(result)) {
 506                                         /* We've already sent the header, we
 507                                          * have no choice but to set pending and
 508                                          * return BUSY.
 509                                          */
 510                                         nsock->pending = req;
 511                                         nsock->sent = sent;
 512                                         return BLK_STS_RESOURCE;
 513                                 }
 514                                 dev_err(disk_to_dev(nbd->disk),
 515                                         "Send data failed (result %d)\n",
 516                                         result);
 517                                 return -EAGAIN;
 518                         }
 519                         /*
 520                          * The completion might already have come in,
 521                          * so break for the last one instead of letting
 522                          * the iterator do it. This prevents use-after-free
 523                          * of the bio.
 524                          */
 525                         if (is_last)
 526                                 break;
 527                 }
 528                 bio = next;
 529         }
 530 out:
 531         nsock->pending = NULL;
 532         nsock->sent = 0;
 533         return 0;
 534 }
 535
 536 /* NULL returned = something went wrong, inform userspace */
 537 static struct nbd_cmd *nbd_read_stat(struct nbd_device *nbd, int index)
 538 {
 539         struct nbd_config *config = nbd->config;
 540         int result;
 541         struct nbd_reply reply;
 542         struct nbd_cmd *cmd;
 543         struct request *req = NULL;
 544         u16 hwq;
 545         u32 tag;
 546         struct kvec iov = {.iov_base = &reply, .iov_len = sizeof(reply)};
 547         struct iov_iter to;
 548
 549         reply.magic = 0;
 550         iov_iter_kvec(&to, READ | ITER_KVEC, &iov, 1, sizeof(reply));
 551         result = sock_xmit(nbd, index, 0, &to, MSG_WAITALL, NULL);
 552         if (result <= 0) {
 553                 if (!nbd_disconnected(config))
 554                         dev_err(disk_to_dev(nbd->disk),
 555                                 "Receive control failed (result %d)\n", result);
 556                 return ERR_PTR(result);
 557         }
 558
 559         if (ntohl(reply.magic) != NBD_REPLY_MAGIC) {
 560                 dev_err(disk_to_dev(nbd->disk), "Wrong magic (0x%lx)\n",
 561                                 (unsigned long)ntohl(reply.magic));
 562                 return ERR_PTR(-EPROTO);
 563         }
 564
 565         memcpy(&tag, reply.handle, sizeof(u32));
 566
 567         hwq = blk_mq_unique_tag_to_hwq(tag);
 568         if (hwq < nbd->tag_set.nr_hw_queues)
 569                 req = blk_mq_tag_to_rq(nbd->tag_set.tags[hwq],
 570                                        blk_mq_unique_tag_to_tag(tag));
 571         if (!req || !blk_mq_request_started(req)) {
 572                 dev_err(disk_to_dev(nbd->disk), "Unexpected reply (%d) %p\n",
 573                         tag, req);
 574                 return ERR_PTR(-ENOENT);
 575         }
 576         cmd = blk_mq_rq_to_pdu(req);
 577         if (ntohl(reply.error)) {
 578                 dev_err(disk_to_dev(nbd->disk), "Other side returned error (%d)\n",
 579                         ntohl(reply.error));
 580                 cmd->status = BLK_STS_IOERR;
 581                 return cmd;
 582         }
 583
 584         dev_dbg(nbd_to_dev(nbd), "request %p: got reply\n", cmd);
 585         if (rq_data_dir(req) != WRITE) {
 586                 struct req_iterator iter;
 587                 struct bio_vec bvec;
 588
 589                 rq_for_each_segment(bvec, req, iter) {
 590                         iov_iter_bvec(&to, ITER_BVEC | READ,
 591                                       &bvec, 1, bvec.bv_len);
 592                         result = sock_xmit(nbd, index, 0, &to, MSG_WAITALL, NULL);
 593                         if (result <= 0) {
 594                                 dev_err(disk_to_dev(nbd->disk), "Receive data failed (result %d)\n",
 595                                         result);
 596                                 /*
 597                                  * If we've disconnected or we only have 1
 598                                  * connection then we need to make sure we
 599                                  * complete this request, otherwise error out
 600                                  * and let the timeout stuff handle resubmitting
 601                                  * this request onto another connection.
 602                                  */
 603                                 if (nbd_disconnected(config) ||
 604                                     config->num_connections <= 1) {
 605                                         cmd->status = BLK_STS_IOERR;
 606                                         return cmd;
 607                                 }
 608                                 return ERR_PTR(-EIO);
 609                         }
 610                         dev_dbg(nbd_to_dev(nbd), "request %p: got %d bytes data\n",
 611                                 cmd, bvec.bv_len);
 612                 }
 613         } else {
 614                 /* See the comment in nbd_queue_rq. */
 615                 wait_for_completion(&cmd->send_complete);
 616         }
 617         return cmd;
 618 }
 619
 620 static void recv_work(struct work_struct *work)
 621 {
 622         struct recv_thread_args *args = container_of(work,
 623                                                      struct recv_thread_args,
 624                                                      work);
 625         struct nbd_device *nbd = args->nbd;
 626         struct nbd_config *config = nbd->config;
 627         struct nbd_cmd *cmd;
 628
 629         while (1) {
 630                 cmd = nbd_read_stat(nbd, args->index);
 631                 if (IS_ERR(cmd)) {
 632                         struct nbd_sock *nsock = config->socks[args->index];
 633
 634                         mutex_lock(&nsock->tx_lock);
 635                         nbd_mark_nsock_dead(nbd, nsock, 1);
 636                         mutex_unlock(&nsock->tx_lock);
 637                         break;
 638                 }
 639
 640                 blk_mq_complete_request(blk_mq_rq_from_pdu(cmd));
 641         }
 642         atomic_dec(&config->recv_threads);
 643         wake_up(&config->recv_wq);
 644         nbd_config_put(nbd);
 645         kfree(args);
 646 }
 647
 648 static void nbd_clear_req(struct request *req, void *data, bool reserved)
 649 {
 650         struct nbd_cmd *cmd;
 651
 652         if (!blk_mq_request_started(req))
 653                 return;
 654         cmd = blk_mq_rq_to_pdu(req);
 655         cmd->status = BLK_STS_IOERR;
 656         blk_mq_complete_request(req);
 657 }
 658
 659 static void nbd_clear_que(struct nbd_device *nbd)
 660 {
 661         blk_mq_quiesce_queue(nbd->disk->queue);
 662         blk_mq_tagset_busy_iter(&nbd->tag_set, nbd_clear_req, NULL);
 663         blk_mq_unquiesce_queue(nbd->disk->queue);
 664         dev_dbg(disk_to_dev(nbd->disk), "queue cleared\n");
 665 }
 666
 667 static int find_fallback(struct nbd_device *nbd, int index)
 668 {
 669         struct nbd_config *config = nbd->config;
 670         int new_index = -1;
 671         struct nbd_sock *nsock = config->socks[index];
 672         int fallback = nsock->fallback_index;
 673
 674         if (test_bit(NBD_DISCONNECTED, &config->runtime_flags))
 675                 return new_index;
 676
 677         if (config->num_connections <= 1) {
 678                 dev_err_ratelimited(disk_to_dev(nbd->disk),
 679                                     "Attempted send on invalid socket\n");
 680                 return new_index;
 681         }
 682
 683         if (fallback >= 0 && fallback < config->num_connections &&
 684             !config->socks[fallback]->dead)
 685                 return fallback;
 686
 687         if (nsock->fallback_index < 0 ||
 688             nsock->fallback_index >= config->num_connections ||
 689             config->socks[nsock->fallback_index]->dead) {
 690                 int i;
 691                 for (i = 0; i < config->num_connections; i++) {
 692                         if (i == index)
 693                                 continue;
 694                         if (!config->socks[i]->dead) {
 695                                 new_index = i;
 696                                 break;
 697                         }
 698                 }
 699                 nsock->fallback_index = new_index;
 700                 if (new_index < 0) {
 701                         dev_err_ratelimited(disk_to_dev(nbd->disk),
 702                                             "Dead connection, failed to find a fallback\n");
 703                         return new_index;
 704                 }
 705         }
 706         new_index = nsock->fallback_index;
 707         return new_index;
 708 }
 709
 710 static int wait_for_reconnect(struct nbd_device *nbd)
 711 {
 712         struct nbd_config *config = nbd->config;
 713         if (!config->dead_conn_timeout)
 714                 return 0;
 715         if (test_bit(NBD_DISCONNECTED, &config->runtime_flags))
 716                 return 0;
 717         wait_event_timeout(config->conn_wait,
 718                            atomic_read(&config->live_connections),
 719                            config->dead_conn_timeout);
 720         return atomic_read(&config->live_connections);
 721 }
 722
 723 static int nbd_handle_cmd(struct nbd_cmd *cmd, int index)
 724 {
 725         struct request *req = blk_mq_rq_from_pdu(cmd);
 726         struct nbd_device *nbd = cmd->nbd;
 727         struct nbd_config *config;
 728         struct nbd_sock *nsock;
 729         int ret;
 730
 731         if (!refcount_inc_not_zero(&nbd->config_refs)) {
 732                 dev_err_ratelimited(disk_to_dev(nbd->disk),
 733                                     "Socks array is empty\n");
 734                 blk_mq_start_request(req);
 735                 return -EINVAL;
 736         }
 737         config = nbd->config;
 738
 739         if (index >= config->num_connections) {
 740                 dev_err_ratelimited(disk_to_dev(nbd->disk),
 741                                     "Attempted send on invalid socket\n");
 742                 nbd_config_put(nbd);
 743                 blk_mq_start_request(req);
 744                 return -EINVAL;
 745         }
 746         cmd->status = BLK_STS_OK;
 747 again:
 748         nsock = config->socks[index];
 749         mutex_lock(&nsock->tx_lock);
 750         if (nsock->dead) {
 751                 int old_index = index;
 752                 index = find_fallback(nbd, index);
 753                 mutex_unlock(&nsock->tx_lock);
 754                 if (index < 0) {
 755                         if (wait_for_reconnect(nbd)) {
 756                                 index = old_index;
 757                                 goto again;
 758                         }
 759                         /* All the sockets should already be down at this point,
 760                          * we just want to make sure that DISCONNECTED is set so
 761                          * any requests that come in that were queue'ed waiting
 762                          * for the reconnect timer don't trigger the timer again
 763                          * and instead just error out.
 764                          */
 765                         sock_shutdown(nbd);
 766                         nbd_config_put(nbd);
 767                         blk_mq_start_request(req);
 768                         return -EIO;
 769                 }
 770                 goto again;
 771         }
 772
 773         /* Handle the case that we have a pending request that was partially
 774          * transmitted that _has_ to be serviced first.  We need to call requeue
 775          * here so that it gets put _after_ the request that is already on the
 776          * dispatch list.
 777          */
 778         blk_mq_start_request(req);
 779         if (unlikely(nsock->pending && nsock->pending != req)) {
 780                 blk_mq_requeue_request(req, true);
 781                 ret = 0;
 782                 goto out;
 783         }
 784         /*
 785          * Some failures are related to the link going down, so anything that
 786          * returns EAGAIN can be retried on a different socket.
 787          */
 788         ret = nbd_send_cmd(nbd, cmd, index);
 789         if (ret == -EAGAIN) {
 790                 dev_err_ratelimited(disk_to_dev(nbd->disk),
 791                                     "Request send failed, requeueing\n");
 792                 nbd_mark_nsock_dead(nbd, nsock, 1);
 793                 blk_mq_requeue_request(req, true);
 794                 ret = 0;
 795         }
 796 out:
 797         mutex_unlock(&nsock->tx_lock);
 798         nbd_config_put(nbd);
 799         return ret;
 800 }
 801
 802 static blk_status_t nbd_queue_rq(struct blk_mq_hw_ctx *hctx,
 803                         const struct blk_mq_queue_data *bd)
 804 {
 805         struct nbd_cmd *cmd = blk_mq_rq_to_pdu(bd->rq);
 806         int ret;
 807
 808         /*
 809          * Since we look at the bio's to send the request over the network we
 810          * need to make sure the completion work doesn't mark this request done
 811          * before we are done doing our send.  This keeps us from dereferencing
 812          * freed data if we have particularly fast completions (ie we get the
 813          * completion before we exit sock_xmit on the last bvec) or in the case
 814          * that the server is misbehaving (or there was an error) before we're
 815          * done sending everything over the wire.
 816          */
 817         init_completion(&cmd->send_complete);
 818
 819         /* We can be called directly from the user space process, which means we
 820          * could possibly have signals pending so our sendmsg will fail.  In
 821          * this case we need to return that we are busy, otherwise error out as
 822          * appropriate.
 823          */
 824         ret = nbd_handle_cmd(cmd, hctx->queue_num);
 825         if (ret < 0)
 826                 ret = BLK_STS_IOERR;
 827         else if (!ret)
 828                 ret = BLK_STS_OK;
 829         complete(&cmd->send_complete);
 830
 831         return ret;
 832 }
 833
 834 static int nbd_add_socket(struct nbd_device *nbd, unsigned long arg,
 835                           bool netlink)
 836 {
 837         struct nbd_config *config = nbd->config;
 838         struct socket *sock;
 839         struct nbd_sock **socks;
 840         struct nbd_sock *nsock;
 841         int err;
 842
 843         sock = sockfd_lookup(arg, &err);
 844         if (!sock)
 845                 return err;
 846
 847         if (!netlink && !nbd->task_setup &&
 848             !test_bit(NBD_BOUND, &config->runtime_flags))
 849                 nbd->task_setup = current;
 850
 851         if (!netlink &&
 852             (nbd->task_setup != current ||
 853              test_bit(NBD_BOUND, &config->runtime_flags))) {
 854                 dev_err(disk_to_dev(nbd->disk),
 855                         "Device being setup by another task");
 856                 sockfd_put(sock);
 857                 return -EBUSY;
 858         }
 859
 860         socks = krealloc(config->socks, (config->num_connections + 1) *
 861                          sizeof(struct nbd_sock *), GFP_KERNEL);
 862         if (!socks) {
 863                 sockfd_put(sock);
 864                 return -ENOMEM;
 865         }
 866         nsock = kzalloc(sizeof(struct nbd_sock), GFP_KERNEL);
 867         if (!nsock) {
 868                 sockfd_put(sock);
 869                 return -ENOMEM;
 870         }
 871
 872         config->socks = socks;
 873
 874         nsock->fallback_index = -1;
 875         nsock->dead = false;
 876         mutex_init(&nsock->tx_lock);
 877         nsock->sock = sock;
 878         nsock->pending = NULL;
 879         nsock->sent = 0;
 880         nsock->cookie = 0;
 881         socks[config->num_connections++] = nsock;
 882         atomic_inc(&config->live_connections);
 883
 884         return 0;
 885 }
 886
 887 static int nbd_reconnect_socket(struct nbd_device *nbd, unsigned long arg)
 888 {
 889         struct nbd_config *config = nbd->config;
 890         struct socket *sock, *old;
 891         struct recv_thread_args *args;
 892         int i;
 893         int err;
 894
 895         sock = sockfd_lookup(arg, &err);
 896         if (!sock)
 897                 return err;
 898
 899         args = kzalloc(sizeof(*args), GFP_KERNEL);
 900         if (!args) {
 901                 sockfd_put(sock);
 902                 return -ENOMEM;
 903         }
 904
 905         for (i = 0; i < config->num_connections; i++) {
 906                 struct nbd_sock *nsock = config->socks[i];
 907
 908                 if (!nsock->dead)
 909                         continue;
 910
 911                 mutex_lock(&nsock->tx_lock);
 912                 if (!nsock->dead) {
 913                         mutex_unlock(&nsock->tx_lock);
 914                         continue;
 915                 }
 916                 sk_set_memalloc(sock->sk);
 917                 if (nbd->tag_set.timeout)
 918                         sock->sk->sk_sndtimeo = nbd->tag_set.timeout;
 919                 atomic_inc(&config->recv_threads);
 920                 refcount_inc(&nbd->config_refs);
 921                 old = nsock->sock;
 922                 nsock->fallback_index = -1;
 923                 nsock->sock = sock;
 924                 nsock->dead = false;
 925                 INIT_WORK(&args->work, recv_work);
 926                 args->index = i;
 927                 args->nbd = nbd;
 928                 nsock->cookie++;
 929                 mutex_unlock(&nsock->tx_lock);
 930                 sockfd_put(old);
 931
 932                 clear_bit(NBD_DISCONNECTED, &config->runtime_flags);
 933
 934                 /* We take the tx_mutex in an error path in the recv_work, so we
 935                  * need to queue_work outside of the tx_mutex.
 936                  */
 937                 queue_work(recv_workqueue, &args->work);
 938
 939                 atomic_inc(&config->live_connections);
 940                 wake_up(&config->conn_wait);
 941                 return 0;
 942         }
 943         sockfd_put(sock);
 944         kfree(args);
 945         return -ENOSPC;
 946 }
 947
 948 static void nbd_bdev_reset(struct block_device *bdev)
 949 {
 950         if (bdev->bd_openers > 1)
 951                 return;
 952         bd_set_size(bdev, 0);
 953         if (max_part > 0) {
 954                 blkdev_reread_part(bdev);
 955                 bdev->bd_invalidated = 1;
 956         }
 957 }
 958
 959 static void nbd_parse_flags(struct nbd_device *nbd)
 960 {
 961         struct nbd_config *config = nbd->config;
 962         if (config->flags & NBD_FLAG_READ_ONLY)
 963                 set_disk_ro(nbd->disk, true);
 964         else
 965                 set_disk_ro(nbd->disk, false);
 966         if (config->flags & NBD_FLAG_SEND_TRIM)
 967                 blk_queue_flag_set(QUEUE_FLAG_DISCARD, nbd->disk->queue);
 968         if (config->flags & NBD_FLAG_SEND_FLUSH) {
 969                 if (config->flags & NBD_FLAG_SEND_FUA)
 970                         blk_queue_write_cache(nbd->disk->queue, true, true);
 971                 else
 972                         blk_queue_write_cache(nbd->disk->queue, true, false);
 973         }
 974         else
 975                 blk_queue_write_cache(nbd->disk->queue, false, false);
 976 }
 977
 978 static void send_disconnects(struct nbd_device *nbd)
 979 {
 980         struct nbd_config *config = nbd->config;
 981         struct nbd_request request = {
 982                 .magic = htonl(NBD_REQUEST_MAGIC),
 983                 .type = htonl(NBD_CMD_DISC),
 984         };
 985         struct kvec iov = {.iov_base = &request, .iov_len = sizeof(request)};
 986         struct iov_iter from;
 987         int i, ret;
 988
 989         for (i = 0; i < config->num_connections; i++) {
 990                 struct nbd_sock *nsock = config->socks[i];
 991
 992                 iov_iter_kvec(&from, WRITE | ITER_KVEC, &iov, 1, sizeof(request));
 993                 mutex_lock(&nsock->tx_lock);
 994                 ret = sock_xmit(nbd, i, 1, &from, 0, NULL);
 995                 if (ret <= 0)
 996                         dev_err(disk_to_dev(nbd->disk),
 997                                 "Send disconnect failed %d\n", ret);
 998                 mutex_unlock(&nsock->tx_lock);
 999         }
1000 }
1001
1002 static int nbd_disconnect(struct nbd_device *nbd)
1003 {
1004         struct nbd_config *config = nbd->config;
1005
1006         dev_info(disk_to_dev(nbd->disk), "NBD_DISCONNECT\n");
1007         set_bit(NBD_DISCONNECT_REQUESTED, &config->runtime_flags);
1008         send_disconnects(nbd);
1009         return 0;
1010 }
1011
1012 static void nbd_clear_sock(struct nbd_device *nbd)
1013 {
1014         sock_shutdown(nbd);
1015         nbd_clear_que(nbd);
1016         nbd->task_setup = NULL;
1017 }
1018
1019 static void nbd_config_put(struct nbd_device *nbd)
1020 {
1021         if (refcount_dec_and_mutex_lock(&nbd->config_refs,
1022                                         &nbd->config_lock)) {
1023                 struct nbd_config *config = nbd->config;
1024                 nbd_dev_dbg_close(nbd);
1025                 nbd_size_clear(nbd);
1026                 if (test_and_clear_bit(NBD_HAS_PID_FILE,
1027                                        &config->runtime_flags))
1028                         device_remove_file(disk_to_dev(nbd->disk), &pid_attr);
1029                 nbd->task_recv = NULL;
1030                 nbd_clear_sock(nbd);
1031                 if (config->num_connections) {
1032                         int i;
1033                         for (i = 0; i < config->num_connections; i++) {
1034                                 sockfd_put(config->socks[i]->sock);
1035                                 kfree(config->socks[i]);
1036                         }
1037                         kfree(config->socks);
1038                 }
1039                 kfree(nbd->config);
1040                 nbd->config = NULL;
1041
1042                 nbd->tag_set.timeout = 0;
1043                 blk_queue_flag_clear(QUEUE_FLAG_DISCARD, nbd->disk->queue);
1044
1045                 mutex_unlock(&nbd->config_lock);
1046                 nbd_put(nbd);
1047                 module_put(THIS_MODULE);
1048         }
1049 }
1050
1051 static int nbd_start_device(struct nbd_device *nbd)
1052 {
1053         struct nbd_config *config = nbd->config;
1054         int num_connections = config->num_connections;
1055         int error = 0, i;
1056
1057         if (nbd->task_recv)
1058                 return -EBUSY;
1059         if (!config->socks)
1060                 return -EINVAL;
1061         if (num_connections > 1 &&
1062             !(config->flags & NBD_FLAG_CAN_MULTI_CONN)) {
1063                 dev_err(disk_to_dev(nbd->disk), "server does not support multiple connections per device.\n");
1064                 return -EINVAL;
1065         }
1066
1067         blk_mq_update_nr_hw_queues(&nbd->tag_set, config->num_connections);
1068         nbd->task_recv = current;
1069
1070         nbd_parse_flags(nbd);
1071
1072         error = device_create_file(disk_to_dev(nbd->disk), &pid_attr);
1073         if (error) {
1074                 dev_err(disk_to_dev(nbd->disk), "device_create_file failed!\n");
1075                 return error;
1076         }
1077         set_bit(NBD_HAS_PID_FILE, &config->runtime_flags);
1078
1079         nbd_dev_dbg_init(nbd);
1080         for (i = 0; i < num_connections; i++) {
1081                 struct recv_thread_args *args;
1082
1083                 args = kzalloc(sizeof(*args), GFP_KERNEL);
1084                 if (!args) {
1085                         sock_shutdown(nbd);
1086                         return -ENOMEM;
1087                 }
1088                 sk_set_memalloc(config->socks[i]->sock->sk);
1089                 if (nbd->tag_set.timeout)
1090                         config->socks[i]->sock->sk->sk_sndtimeo =
1091                                 nbd->tag_set.timeout;
1092                 atomic_inc(&config->recv_threads);
1093                 refcount_inc(&nbd->config_refs);
1094                 INIT_WORK(&args->work, recv_work);
1095                 args->nbd = nbd;
1096                 args->index = i;
1097                 queue_work(recv_workqueue, &args->work);
1098         }
1099         nbd_size_update(nbd);
1100         return error;
1101 }
1102
1103 static int nbd_start_device_ioctl(struct nbd_device *nbd, struct block_device *bdev)
1104 {
1105         struct nbd_config *config = nbd->config;
1106         int ret;
1107
1108         ret = nbd_start_device(nbd);
1109         if (ret)
1110                 return ret;
1111
1112         bd_set_size(bdev, config->bytesize);
1113         if (max_part)
1114                 bdev->bd_invalidated = 1;
1115         mutex_unlock(&nbd->config_lock);
1116         ret = wait_event_interruptible(config->recv_wq,
1117                                          atomic_read(&config->recv_threads) == 0);
1118         if (ret)
1119                 sock_shutdown(nbd);
1120         mutex_lock(&nbd->config_lock);
1121         bd_set_size(bdev, 0);
1122         /* user requested, ignore socket errors */
1123         if (test_bit(NBD_DISCONNECT_REQUESTED, &config->runtime_flags))
1124                 ret = 0;
1125         if (test_bit(NBD_TIMEDOUT, &config->runtime_flags))
1126                 ret = -ETIMEDOUT;
1127         return ret;
1128 }
1129
1130 static void nbd_clear_sock_ioctl(struct nbd_device *nbd,
1131                                  struct block_device *bdev)
1132 {
1133         sock_shutdown(nbd);
1134         kill_bdev(bdev);
1135         nbd_bdev_reset(bdev);
1136         if (test_and_clear_bit(NBD_HAS_CONFIG_REF,
1137                                &nbd->config->runtime_flags))
1138                 nbd_config_put(nbd);
1139 }
1140
1141 /* Must be called with config_lock held */
1142 static int __nbd_ioctl(struct block_device *bdev, struct nbd_device *nbd,
1143                        unsigned int cmd, unsigned long arg)
1144 {
1145         struct nbd_config *config = nbd->config;
1146
1147         switch (cmd) {
1148         case NBD_DISCONNECT:
1149                 return nbd_disconnect(nbd);
1150         case NBD_CLEAR_SOCK:
1151                 nbd_clear_sock_ioctl(nbd, bdev);
1152                 return 0;
1153         case NBD_SET_SOCK:
1154                 return nbd_add_socket(nbd, arg, false);
1155         case NBD_SET_BLKSIZE:
1156                 nbd_size_set(nbd, arg,
1157                              div_s64(config->bytesize, arg));
1158                 return 0;
1159         case NBD_SET_SIZE:
1160                 nbd_size_set(nbd, config->blksize,
1161                              div_s64(arg, config->blksize));
1162                 return 0;
1163         case NBD_SET_SIZE_BLOCKS:
1164                 nbd_size_set(nbd, config->blksize, arg);
1165                 return 0;
1166         case NBD_SET_TIMEOUT:
1167                 if (arg) {
1168                         nbd->tag_set.timeout = arg * HZ;
1169                         blk_queue_rq_timeout(nbd->disk->queue, arg * HZ);
1170                 }
1171                 return 0;
1172
1173         case NBD_SET_FLAGS:
1174                 config->flags = arg;
1175                 return 0;
1176         case NBD_DO_IT:
1177                 return nbd_start_device_ioctl(nbd, bdev);
1178         case NBD_CLEAR_QUE:
1179                 /*
1180                  * This is for compatibility only.  The queue is always cleared
1181                  * by NBD_DO_IT or NBD_CLEAR_SOCK.
1182                  */
1183                 return 0;
1184         case NBD_PRINT_DEBUG:
1185                 /*
1186                  * For compatibility only, we no longer keep a list of
1187                  * outstanding requests.
1188                  */
1189                 return 0;
1190         }
1191         return -ENOTTY;
1192 }
1193
1194 static int nbd_ioctl(struct block_device *bdev, fmode_t mode,
1195                      unsigned int cmd, unsigned long arg)
1196 {
1197         struct nbd_device *nbd = bdev->bd_disk->private_data;
1198         struct nbd_config *config = nbd->config;
1199         int error = -EINVAL;
1200
1201         if (!capable(CAP_SYS_ADMIN))
1202                 return -EPERM;
1203
1204         /* The block layer will pass back some non-nbd ioctls in case we have
1205          * special handling for them, but we don't so just return an error.
1206          */
1207         if (_IOC_TYPE(cmd) != 0xab)
1208                 return -EINVAL;
1209
1210         mutex_lock(&nbd->config_lock);
1211
1212         /* Don't allow ioctl operations on a nbd device that was created with
1213          * netlink, unless it's DISCONNECT or CLEAR_SOCK, which are fine.
1214          */
1215         if (!test_bit(NBD_BOUND, &config->runtime_flags) ||
1216             (cmd == NBD_DISCONNECT || cmd == NBD_CLEAR_SOCK))
1217                 error = __nbd_ioctl(bdev, nbd, cmd, arg);
1218         else
1219                 dev_err(nbd_to_dev(nbd), "Cannot use ioctl interface on a netlink controlled device.\n");
1220         mutex_unlock(&nbd->config_lock);
1221         return error;
1222 }
1223
1224 static struct nbd_config *nbd_alloc_config(void)
1225 {
1226         struct nbd_config *config;
1227
1228         config = kzalloc(sizeof(struct nbd_config), GFP_NOFS);
1229         if (!config)
1230                 return NULL;
1231         atomic_set(&config->recv_threads, 0);
1232         init_waitqueue_head(&config->recv_wq);
1233         init_waitqueue_head(&config->conn_wait);
1234         config->blksize = 1024;
1235         atomic_set(&config->live_connections, 0);
1236         try_module_get(THIS_MODULE);
1237         return config;
1238 }
1239
1240 static int nbd_open(struct block_device *bdev, fmode_t mode)
1241 {
1242         struct nbd_device *nbd;
1243         int ret = 0;
1244
1245         mutex_lock(&nbd_index_mutex);
1246         nbd = bdev->bd_disk->private_data;
1247         if (!nbd) {
1248                 ret = -ENXIO;
1249                 goto out;
1250         }
1251         if (!refcount_inc_not_zero(&nbd->refs)) {
1252                 ret = -ENXIO;
1253                 goto out;
1254         }
1255         if (!refcount_inc_not_zero(&nbd->config_refs)) {
1256                 struct nbd_config *config;
1257
1258                 mutex_lock(&nbd->config_lock);
1259                 if (refcount_inc_not_zero(&nbd->config_refs)) {
1260                         mutex_unlock(&nbd->config_lock);
1261                         goto out;
1262                 }
1263                 config = nbd->config = nbd_alloc_config();
1264                 if (!config) {
1265                         ret = -ENOMEM;
1266                         mutex_unlock(&nbd->config_lock);
1267                         goto out;
1268                 }
1269                 refcount_set(&nbd->config_refs, 1);
1270                 refcount_inc(&nbd->refs);
1271                 mutex_unlock(&nbd->config_lock);
1272         }
1273 out:
1274         mutex_unlock(&nbd_index_mutex);
1275         return ret;
1276 }
1277
1278 static void nbd_release(struct gendisk *disk, fmode_t mode)
1279 {
1280         struct nbd_device *nbd = disk->private_data;
1281         nbd_config_put(nbd);
1282         nbd_put(nbd);
1283 }
1284
1285 static const struct block_device_operations nbd_fops =
1286 {
1287         .owner =        THIS_MODULE,
1288         .open =         nbd_open,
1289         .release =      nbd_release,
1290         .ioctl =        nbd_ioctl,
1291         .compat_ioctl = nbd_ioctl,
1292 };
1293
1294 #if IS_ENABLED(CONFIG_DEBUG_FS)
1295
1296 static int nbd_dbg_tasks_show(struct seq_file *s, void *unused)
1297 {
1298         struct nbd_device *nbd = s->private;
1299
1300         if (nbd->task_recv)
1301                 seq_printf(s, "recv: %d\n", task_pid_nr(nbd->task_recv));
1302
1303         return 0;
1304 }
1305
1306 static int nbd_dbg_tasks_open(struct inode *inode, struct file *file)
1307 {
1308         return single_open(file, nbd_dbg_tasks_show, inode->i_private);
1309 }
1310
1311 static const struct file_operations nbd_dbg_tasks_ops = {
1312         .open = nbd_dbg_tasks_open,
1313         .read = seq_read,
1314         .llseek = seq_lseek,
1315         .release = single_release,
1316 };
1317
1318 static int nbd_dbg_flags_show(struct seq_file *s, void *unused)
1319 {
1320         struct nbd_device *nbd = s->private;
1321         u32 flags = nbd->config->flags;
1322
1323         seq_printf(s, "Hex: 0x%08x\n\n", flags);
1324
1325         seq_puts(s, "Known flags:\n");
1326
1327         if (flags & NBD_FLAG_HAS_FLAGS)
1328                 seq_puts(s, "NBD_FLAG_HAS_FLAGS\n");
1329         if (flags & NBD_FLAG_READ_ONLY)
1330                 seq_puts(s, "NBD_FLAG_READ_ONLY\n");
1331         if (flags & NBD_FLAG_SEND_FLUSH)
1332                 seq_puts(s, "NBD_FLAG_SEND_FLUSH\n");
1333         if (flags & NBD_FLAG_SEND_FUA)
1334                 seq_puts(s, "NBD_FLAG_SEND_FUA\n");
1335         if (flags & NBD_FLAG_SEND_TRIM)
1336                 seq_puts(s, "NBD_FLAG_SEND_TRIM\n");
1337
1338         return 0;
1339 }
1340
1341 static int nbd_dbg_flags_open(struct inode *inode, struct file *file)
1342 {
1343         return single_open(file, nbd_dbg_flags_show, inode->i_private);
1344 }
1345
1346 static const struct file_operations nbd_dbg_flags_ops = {
1347         .open = nbd_dbg_flags_open,
1348         .read = seq_read,
1349         .llseek = seq_lseek,
1350         .release = single_release,
1351 };
1352
1353 static int nbd_dev_dbg_init(struct nbd_device *nbd)
1354 {
1355         struct dentry *dir;
1356         struct nbd_config *config = nbd->config;
1357
1358         if (!nbd_dbg_dir)
1359                 return -EIO;
1360
1361         dir = debugfs_create_dir(nbd_name(nbd), nbd_dbg_dir);
1362         if (!dir) {
1363                 dev_err(nbd_to_dev(nbd), "Failed to create debugfs dir for '%s'\n",
1364                         nbd_name(nbd));
1365                 return -EIO;
1366         }
1367         config->dbg_dir = dir;
1368
1369         debugfs_create_file("tasks", 0444, dir, nbd, &nbd_dbg_tasks_ops);
1370         debugfs_create_u64("size_bytes", 0444, dir, &config->bytesize);
1371         debugfs_create_u32("timeout", 0444, dir, &nbd->tag_set.timeout);
1372         debugfs_create_u64("blocksize", 0444, dir, &config->blksize);
1373         debugfs_create_file("flags", 0444, dir, nbd, &nbd_dbg_flags_ops);
1374
1375         return 0;
1376 }
1377
1378 static void nbd_dev_dbg_close(struct nbd_device *nbd)
1379 {
1380         debugfs_remove_recursive(nbd->config->dbg_dir);
1381 }
1382
1383 static int nbd_dbg_init(void)
1384 {
1385         struct dentry *dbg_dir;
1386
1387         dbg_dir = debugfs_create_dir("nbd", NULL);
1388         if (!dbg_dir)
1389                 return -EIO;
1390
1391         nbd_dbg_dir = dbg_dir;
1392
1393         return 0;
1394 }
1395
1396 static void nbd_dbg_close(void)
1397 {
1398         debugfs_remove_recursive(nbd_dbg_dir);
1399 }
1400
1401 #else  /* IS_ENABLED(CONFIG_DEBUG_FS) */
1402
1403 static int nbd_dev_dbg_init(struct nbd_device *nbd)
1404 {
1405         return 0;
1406 }
1407
1408 static void nbd_dev_dbg_close(struct nbd_device *nbd)
1409 {
1410 }
1411
1412 static int nbd_dbg_init(void)
1413 {
1414         return 0;
1415 }
1416
1417 static void nbd_dbg_close(void)
1418 {
1419 }
1420
1421 #endif
1422
1423 static int nbd_init_request(struct blk_mq_tag_set *set, struct request *rq,
1424                             unsigned int hctx_idx, unsigned int numa_node)
1425 {
1426         struct nbd_cmd *cmd = blk_mq_rq_to_pdu(rq);
1427         cmd->nbd = set->driver_data;
1428         return 0;
1429 }
1430
1431 static const struct blk_mq_ops nbd_mq_ops = {
1432         .queue_rq       = nbd_queue_rq,
1433         .complete       = nbd_complete_rq,
1434         .init_request   = nbd_init_request,
1435         .timeout        = nbd_xmit_timeout,
1436 };
1437
1438 static int nbd_dev_add(int index)
1439 {
1440         struct nbd_device *nbd;
1441         struct gendisk *disk;
1442         struct request_queue *q;
1443         int err = -ENOMEM;
1444
1445         nbd = kzalloc(sizeof(struct nbd_device), GFP_KERNEL);
1446         if (!nbd)
1447                 goto out;
1448
1449         disk = alloc_disk(1 << part_shift);
1450         if (!disk)
1451                 goto out_free_nbd;
1452
1453         if (index >= 0) {
1454                 err = idr_alloc(&nbd_index_idr, nbd, index, index + 1,
1455                                 GFP_KERNEL);
1456                 if (err == -ENOSPC)
1457                         err = -EEXIST;
1458         } else {
1459                 err = idr_alloc(&nbd_index_idr, nbd, 0, 0, GFP_KERNEL);
1460                 if (err >= 0)
1461                         index = err;
1462         }
1463         if (err < 0)
1464                 goto out_free_disk;
1465
1466         nbd->index = index;
1467         nbd->disk = disk;
1468         nbd->tag_set.ops = &nbd_mq_ops;
1469         nbd->tag_set.nr_hw_queues = 1;
1470         nbd->tag_set.queue_depth = 128;
1471         nbd->tag_set.numa_node = NUMA_NO_NODE;
1472         nbd->tag_set.cmd_size = sizeof(struct nbd_cmd);
1473         nbd->tag_set.flags = BLK_MQ_F_SHOULD_MERGE |
1474                 BLK_MQ_F_SG_MERGE | BLK_MQ_F_BLOCKING;
1475         nbd->tag_set.driver_data = nbd;
1476
1477         err = blk_mq_alloc_tag_set(&nbd->tag_set);
1478         if (err)
1479                 goto out_free_idr;
1480
1481         q = blk_mq_init_queue(&nbd->tag_set);
1482         if (IS_ERR(q)) {
1483                 err = PTR_ERR(q);
1484                 goto out_free_tags;
1485         }
1486         disk->queue = q;
1487
1488         /*
1489          * Tell the block layer that we are not a rotational device
1490          */
1491         blk_queue_flag_set(QUEUE_FLAG_NONROT, disk->queue);
1492         blk_queue_flag_clear(QUEUE_FLAG_ADD_RANDOM, disk->queue);
1493         disk->queue->limits.discard_granularity = 512;
1494         blk_queue_max_discard_sectors(disk->queue, UINT_MAX);
1495         blk_queue_max_segment_size(disk->queue, UINT_MAX);
1496         blk_queue_max_segments(disk->queue, USHRT_MAX);
1497         blk_queue_max_hw_sectors(disk->queue, 65536);
1498         disk->queue->limits.max_sectors = 256;
1499
1500         mutex_init(&nbd->config_lock);
1501         refcount_set(&nbd->config_refs, 0);
1502         refcount_set(&nbd->refs, 1);
1503         INIT_LIST_HEAD(&nbd->list);
1504         disk->major = NBD_MAJOR;
1505         disk->first_minor = index << part_shift;
1506         disk->fops = &nbd_fops;
1507         disk->private_data = nbd;
1508         sprintf(disk->disk_name, "nbd%d", index);
1509         add_disk(disk);
1510         nbd_total_devices++;
1511         return index;
1512
1513 out_free_tags:
1514         blk_mq_free_tag_set(&nbd->tag_set);
1515 out_free_idr:
1516         idr_remove(&nbd_index_idr, index);
1517 out_free_disk:
1518         put_disk(disk);
1519 out_free_nbd:
1520         kfree(nbd);
1521 out:
1522         return err;
1523 }
1524
1525 static int find_free_cb(int id, void *ptr, void *data)
1526 {
1527         struct nbd_device *nbd = ptr;
1528         struct nbd_device **found = data;
1529
1530         if (!refcount_read(&nbd->config_refs)) {
1531                 *found = nbd;
1532                 return 1;
1533         }
1534         return 0;
1535 }
1536
1537 /* Netlink interface. */
1538 static struct nla_policy nbd_attr_policy[NBD_ATTR_MAX + 1] = {
1539         [NBD_ATTR_INDEX]                =       { .type = NLA_U32 },
1540         [NBD_ATTR_SIZE_BYTES]           =       { .type = NLA_U64 },
1541         [NBD_ATTR_BLOCK_SIZE_BYTES]     =       { .type = NLA_U64 },
1542         [NBD_ATTR_TIMEOUT]              =       { .type = NLA_U64 },
1543         [NBD_ATTR_SERVER_FLAGS]         =       { .type = NLA_U64 },
1544         [NBD_ATTR_CLIENT_FLAGS]         =       { .type = NLA_U64 },
1545         [NBD_ATTR_SOCKETS]              =       { .type = NLA_NESTED},
1546         [NBD_ATTR_DEAD_CONN_TIMEOUT]    =       { .type = NLA_U64 },
1547         [NBD_ATTR_DEVICE_LIST]          =       { .type = NLA_NESTED},
1548 };
1549
1550 static struct nla_policy nbd_sock_policy[NBD_SOCK_MAX + 1] = {
1551         [NBD_SOCK_FD]                   =       { .type = NLA_U32 },
1552 };
1553
1554 /* We don't use this right now since we don't parse the incoming list, but we
1555  * still want it here so userspace knows what to expect.
1556  */
1557 static struct nla_policy __attribute__((unused))
1558 nbd_device_policy[NBD_DEVICE_ATTR_MAX + 1] = {
1559         [NBD_DEVICE_INDEX]              =       { .type = NLA_U32 },
1560         [NBD_DEVICE_CONNECTED]          =       { .type = NLA_U8 },
1561 };
1562
1563 static int nbd_genl_connect(struct sk_buff *skb, struct genl_info *info)
1564 {
1565         struct nbd_device *nbd = NULL;
1566         struct nbd_config *config;
1567         int index = -1;
1568         int ret;
1569         bool put_dev = false;
1570
1571         if (!netlink_capable(skb, CAP_SYS_ADMIN))
1572                 return -EPERM;
1573
1574         if (info->attrs[NBD_ATTR_INDEX])
1575                 index = nla_get_u32(info->attrs[NBD_ATTR_INDEX]);
1576         if (!info->attrs[NBD_ATTR_SOCKETS]) {
1577                 printk(KERN_ERR "nbd: must specify at least one socket\n");
1578                 return -EINVAL;
1579         }
1580         if (!info->attrs[NBD_ATTR_SIZE_BYTES]) {
1581                 printk(KERN_ERR "nbd: must specify a size in bytes for the device\n");
1582                 return -EINVAL;
1583         }
1584 again:
1585         mutex_lock(&nbd_index_mutex);
1586         if (index == -1) {
1587                 ret = idr_for_each(&nbd_index_idr, &find_free_cb, &nbd);
1588                 if (ret == 0) {
1589                         int new_index;
1590                         new_index = nbd_dev_add(-1);
1591                         if (new_index < 0) {
1592                                 mutex_unlock(&nbd_index_mutex);
1593                                 printk(KERN_ERR "nbd: failed to add new device\n");
1594                                 return new_index;
1595                         }
1596                         nbd = idr_find(&nbd_index_idr, new_index);
1597                 }
1598         } else {
1599                 nbd = idr_find(&nbd_index_idr, index);
1600                 if (!nbd) {
1601                         ret = nbd_dev_add(index);
1602                         if (ret < 0) {
1603                                 mutex_unlock(&nbd_index_mutex);
1604                                 printk(KERN_ERR "nbd: failed to add new device\n");
1605                                 return ret;
1606                         }
1607                         nbd = idr_find(&nbd_index_idr, index);
1608                 }
1609         }
1610         if (!nbd) {
1611                 printk(KERN_ERR "nbd: couldn't find device at index %d\n",
1612                        index);
1613                 mutex_unlock(&nbd_index_mutex);
1614                 return -EINVAL;
1615         }
1616         if (!refcount_inc_not_zero(&nbd->refs)) {
1617                 mutex_unlock(&nbd_index_mutex);
1618                 if (index == -1)
1619                         goto again;
1620                 printk(KERN_ERR "nbd: device at index %d is going down\n",
1621                        index);
1622                 return -EINVAL;
1623         }
1624         mutex_unlock(&nbd_index_mutex);
1625
1626         mutex_lock(&nbd->config_lock);
1627         if (refcount_read(&nbd->config_refs)) {
1628                 mutex_unlock(&nbd->config_lock);
1629                 nbd_put(nbd);
1630                 if (index == -1)
1631                         goto again;
1632                 printk(KERN_ERR "nbd: nbd%d already in use\n", index);
1633                 return -EBUSY;
1634         }
1635         if (WARN_ON(nbd->config)) {
1636                 mutex_unlock(&nbd->config_lock);
1637                 nbd_put(nbd);
1638                 return -EINVAL;
1639         }
1640         config = nbd->config = nbd_alloc_config();
1641         if (!nbd->config) {
1642                 mutex_unlock(&nbd->config_lock);
1643                 nbd_put(nbd);
1644                 printk(KERN_ERR "nbd: couldn't allocate config\n");
1645                 return -ENOMEM;
1646         }
1647         refcount_set(&nbd->config_refs, 1);
1648         set_bit(NBD_BOUND, &config->runtime_flags);
1649
1650         if (info->attrs[NBD_ATTR_SIZE_BYTES]) {
1651                 u64 bytes = nla_get_u64(info->attrs[NBD_ATTR_SIZE_BYTES]);
1652                 nbd_size_set(nbd, config->blksize,
1653                              div64_u64(bytes, config->blksize));
1654         }
1655         if (info->attrs[NBD_ATTR_BLOCK_SIZE_BYTES]) {
1656                 u64 bsize =
1657                         nla_get_u64(info->attrs[NBD_ATTR_BLOCK_SIZE_BYTES]);
1658                 nbd_size_set(nbd, bsize, div64_u64(config->bytesize, bsize));
1659         }
1660         if (info->attrs[NBD_ATTR_TIMEOUT]) {
1661                 u64 timeout = nla_get_u64(info->attrs[NBD_ATTR_TIMEOUT]);
1662                 nbd->tag_set.timeout = timeout * HZ;
1663                 blk_queue_rq_timeout(nbd->disk->queue, timeout * HZ);
1664         }
1665         if (info->attrs[NBD_ATTR_DEAD_CONN_TIMEOUT]) {
1666                 config->dead_conn_timeout =
1667                         nla_get_u64(info->attrs[NBD_ATTR_DEAD_CONN_TIMEOUT]);
1668                 config->dead_conn_timeout *= HZ;
1669         }
1670         if (info->attrs[NBD_ATTR_SERVER_FLAGS])
1671                 config->flags =
1672                         nla_get_u64(info->attrs[NBD_ATTR_SERVER_FLAGS]);
1673         if (info->attrs[NBD_ATTR_CLIENT_FLAGS]) {
1674                 u64 flags = nla_get_u64(info->attrs[NBD_ATTR_CLIENT_FLAGS]);
1675                 if (flags & NBD_CFLAG_DESTROY_ON_DISCONNECT) {
1676                         set_bit(NBD_DESTROY_ON_DISCONNECT,
1677                                 &config->runtime_flags);
1678                         put_dev = true;
1679                 }
1680         }
1681
1682         if (info->attrs[NBD_ATTR_SOCKETS]) {
1683                 struct nlattr *attr;
1684                 int rem, fd;
1685
1686                 nla_for_each_nested(attr, info->attrs[NBD_ATTR_SOCKETS],
1687                                     rem) {
1688                         struct nlattr *socks[NBD_SOCK_MAX+1];
1689
1690                         if (nla_type(attr) != NBD_SOCK_ITEM) {
1691                                 printk(KERN_ERR "nbd: socks must be embedded in a SOCK_ITEM attr\n");
1692                                 ret = -EINVAL;
1693                                 goto out;
1694                         }
1695                         ret = nla_parse_nested(socks, NBD_SOCK_MAX, attr,
1696                                                nbd_sock_policy, info->extack);
1697                         if (ret != 0) {
1698                                 printk(KERN_ERR "nbd: error processing sock list\n");
1699                                 ret = -EINVAL;
1700                                 goto out;
1701                         }
1702                         if (!socks[NBD_SOCK_FD])
1703                                 continue;
1704                         fd = (int)nla_get_u32(socks[NBD_SOCK_FD]);
1705                         ret = nbd_add_socket(nbd, fd, true);
1706                         if (ret)
1707                                 goto out;
1708                 }
1709         }
1710         ret = nbd_start_device(nbd);
1711 out:
1712         mutex_unlock(&nbd->config_lock);
1713         if (!ret) {
1714                 set_bit(NBD_HAS_CONFIG_REF, &config->runtime_flags);
1715                 refcount_inc(&nbd->config_refs);
1716                 nbd_connect_reply(info, nbd->index);
1717         }
1718         nbd_config_put(nbd);
1719         if (put_dev)
1720                 nbd_put(nbd);
1721         return ret;
1722 }
1723
1724 static int nbd_genl_disconnect(struct sk_buff *skb, struct genl_info *info)
1725 {
1726         struct nbd_device *nbd;
1727         int index;
1728
1729         if (!netlink_capable(skb, CAP_SYS_ADMIN))
1730                 return -EPERM;
1731
1732         if (!info->attrs[NBD_ATTR_INDEX]) {
1733                 printk(KERN_ERR "nbd: must specify an index to disconnect\n");
1734                 return -EINVAL;
1735         }
1736         index = nla_get_u32(info->attrs[NBD_ATTR_INDEX]);
1737         mutex_lock(&nbd_index_mutex);
1738         nbd = idr_find(&nbd_index_idr, index);
1739         if (!nbd) {
1740                 mutex_unlock(&nbd_index_mutex);
1741                 printk(KERN_ERR "nbd: couldn't find device at index %d\n",
1742                        index);
1743                 return -EINVAL;
1744         }
1745         if (!refcount_inc_not_zero(&nbd->refs)) {
1746                 mutex_unlock(&nbd_index_mutex);
1747                 printk(KERN_ERR "nbd: device at index %d is going down\n",
1748                        index);
1749                 return -EINVAL;
1750         }
1751         mutex_unlock(&nbd_index_mutex);
1752         if (!refcount_inc_not_zero(&nbd->config_refs)) {
1753                 nbd_put(nbd);
1754                 return 0;
1755         }
1756         mutex_lock(&nbd->config_lock);
1757         nbd_disconnect(nbd);
1758         mutex_unlock(&nbd->config_lock);
1759         if (test_and_clear_bit(NBD_HAS_CONFIG_REF,
1760                                &nbd->config->runtime_flags))
1761                 nbd_config_put(nbd);
1762         nbd_config_put(nbd);
1763         nbd_put(nbd);
1764         return 0;
1765 }
1766
1767 static int nbd_genl_reconfigure(struct sk_buff *skb, struct genl_info *info)
1768 {
1769         struct nbd_device *nbd = NULL;
1770         struct nbd_config *config;
1771         int index;
1772         int ret = -EINVAL;
1773         bool put_dev = false;
1774
1775         if (!netlink_capable(skb, CAP_SYS_ADMIN))
1776                 return -EPERM;
1777
1778         if (!info->attrs[NBD_ATTR_INDEX]) {
1779                 printk(KERN_ERR "nbd: must specify a device to reconfigure\n");
1780                 return -EINVAL;
1781         }
1782         index = nla_get_u32(info->attrs[NBD_ATTR_INDEX]);
1783         mutex_lock(&nbd_index_mutex);
1784         nbd = idr_find(&nbd_index_idr, index);
1785         if (!nbd) {
1786                 mutex_unlock(&nbd_index_mutex);
1787                 printk(KERN_ERR "nbd: couldn't find a device at index %d\n",
1788                        index);
1789                 return -EINVAL;
1790         }
1791         if (!refcount_inc_not_zero(&nbd->refs)) {
1792                 mutex_unlock(&nbd_index_mutex);
1793                 printk(KERN_ERR "nbd: device at index %d is going down\n",
1794                        index);
1795                 return -EINVAL;
1796         }
1797         mutex_unlock(&nbd_index_mutex);
1798
1799         if (!refcount_inc_not_zero(&nbd->config_refs)) {
1800                 dev_err(nbd_to_dev(nbd),
1801                         "not configured, cannot reconfigure\n");
1802                 nbd_put(nbd);
1803                 return -EINVAL;
1804         }
1805
1806         mutex_lock(&nbd->config_lock);
1807         config = nbd->config;
1808         if (!test_bit(NBD_BOUND, &config->runtime_flags) ||
1809             !nbd->task_recv) {
1810                 dev_err(nbd_to_dev(nbd),
1811                         "not configured, cannot reconfigure\n");
1812                 goto out;
1813         }
1814
1815         if (info->attrs[NBD_ATTR_TIMEOUT]) {
1816                 u64 timeout = nla_get_u64(info->attrs[NBD_ATTR_TIMEOUT]);
1817                 nbd->tag_set.timeout = timeout * HZ;
1818                 blk_queue_rq_timeout(nbd->disk->queue, timeout * HZ);
1819         }
1820         if (info->attrs[NBD_ATTR_DEAD_CONN_TIMEOUT]) {
1821                 config->dead_conn_timeout =
1822                         nla_get_u64(info->attrs[NBD_ATTR_DEAD_CONN_TIMEOUT]);
1823                 config->dead_conn_timeout *= HZ;
1824         }
1825         if (info->attrs[NBD_ATTR_CLIENT_FLAGS]) {
1826                 u64 flags = nla_get_u64(info->attrs[NBD_ATTR_CLIENT_FLAGS]);
1827                 if (flags & NBD_CFLAG_DESTROY_ON_DISCONNECT) {
1828                         if (!test_and_set_bit(NBD_DESTROY_ON_DISCONNECT,
1829                                               &config->runtime_flags))
1830                                 put_dev = true;
1831                 } else {
1832                         if (test_and_clear_bit(NBD_DESTROY_ON_DISCONNECT,
1833                                                &config->runtime_flags))
1834                                 refcount_inc(&nbd->refs);
1835                 }
1836         }
1837
1838         if (info->attrs[NBD_ATTR_SOCKETS]) {
1839                 struct nlattr *attr;
1840                 int rem, fd;
1841
1842                 nla_for_each_nested(attr, info->attrs[NBD_ATTR_SOCKETS],
1843                                     rem) {
1844                         struct nlattr *socks[NBD_SOCK_MAX+1];
1845
1846                         if (nla_type(attr) != NBD_SOCK_ITEM) {
1847                                 printk(KERN_ERR "nbd: socks must be embedded in a SOCK_ITEM attr\n");
1848                                 ret = -EINVAL;
1849                                 goto out;
1850                         }
1851                         ret = nla_parse_nested(socks, NBD_SOCK_MAX, attr,
1852                                                nbd_sock_policy, info->extack);
1853                         if (ret != 0) {
1854                                 printk(KERN_ERR "nbd: error processing sock list\n");
1855                                 ret = -EINVAL;
1856                                 goto out;
1857                         }
1858                         if (!socks[NBD_SOCK_FD])
1859                                 continue;
1860                         fd = (int)nla_get_u32(socks[NBD_SOCK_FD]);
1861                         ret = nbd_reconnect_socket(nbd, fd);
1862                         if (ret) {
1863                                 if (ret == -ENOSPC)
1864                                         ret = 0;
1865                                 goto out;
1866                         }
1867                         dev_info(nbd_to_dev(nbd), "reconnected socket\n");
1868                 }
1869         }
1870 out:
1871         mutex_unlock(&nbd->config_lock);
1872         nbd_config_put(nbd);
1873         nbd_put(nbd);
1874         if (put_dev)
1875                 nbd_put(nbd);
1876         return ret;
1877 }
1878
1879 static const struct genl_ops nbd_connect_genl_ops[] = {
1880         {
1881                 .cmd    = NBD_CMD_CONNECT,
1882                 .policy = nbd_attr_policy,
1883                 .doit   = nbd_genl_connect,
1884         },
1885         {
1886                 .cmd    = NBD_CMD_DISCONNECT,
1887                 .policy = nbd_attr_policy,
1888                 .doit   = nbd_genl_disconnect,
1889         },
1890         {
1891                 .cmd    = NBD_CMD_RECONFIGURE,
1892                 .policy = nbd_attr_policy,
1893                 .doit   = nbd_genl_reconfigure,
1894         },
1895         {
1896                 .cmd    = NBD_CMD_STATUS,
1897                 .policy = nbd_attr_policy,
1898                 .doit   = nbd_genl_status,
1899         },
1900 };
1901
1902 static const struct genl_multicast_group nbd_mcast_grps[] = {
1903         { .name = NBD_GENL_MCAST_GROUP_NAME, },
1904 };
1905
1906 static struct genl_family nbd_genl_family __ro_after_init = {
1907         .hdrsize        = 0,
1908         .name           = NBD_GENL_FAMILY_NAME,
1909         .version        = NBD_GENL_VERSION,
1910         .module         = THIS_MODULE,
1911         .ops            = nbd_connect_genl_ops,
1912         .n_ops          = ARRAY_SIZE(nbd_connect_genl_ops),
1913         .maxattr        = NBD_ATTR_MAX,
1914         .mcgrps         = nbd_mcast_grps,
1915         .n_mcgrps       = ARRAY_SIZE(nbd_mcast_grps),
1916 };
1917
1918 static int populate_nbd_status(struct nbd_device *nbd, struct sk_buff *reply)
1919 {
1920         struct nlattr *dev_opt;
1921         u8 connected = 0;
1922         int ret;
1923
1924         /* This is a little racey, but for status it's ok.  The
1925          * reason we don't take a ref here is because we can't
1926          * take a ref in the index == -1 case as we would need
1927          * to put under the nbd_index_mutex, which could
1928          * deadlock if we are configured to remove ourselves
1929          * once we're disconnected.
1930          */
1931         if (refcount_read(&nbd->config_refs))
1932                 connected = 1;
1933         dev_opt = nla_nest_start(reply, NBD_DEVICE_ITEM);
1934         if (!dev_opt)
1935                 return -EMSGSIZE;
1936         ret = nla_put_u32(reply, NBD_DEVICE_INDEX, nbd->index);
1937         if (ret)
1938                 return -EMSGSIZE;
1939         ret = nla_put_u8(reply, NBD_DEVICE_CONNECTED,
1940                          connected);
1941         if (ret)
1942                 return -EMSGSIZE;
1943         nla_nest_end(reply, dev_opt);
1944         return 0;
1945 }
1946
1947 static int status_cb(int id, void *ptr, void *data)
1948 {
1949         struct nbd_device *nbd = ptr;
1950         return populate_nbd_status(nbd, (struct sk_buff *)data);
1951 }
1952
1953 static int nbd_genl_status(struct sk_buff *skb, struct genl_info *info)
1954 {
1955         struct nlattr *dev_list;
1956         struct sk_buff *reply;
1957         void *reply_head;
1958         size_t msg_size;
1959         int index = -1;
1960         int ret = -ENOMEM;
1961
1962         if (info->attrs[NBD_ATTR_INDEX])
1963                 index = nla_get_u32(info->attrs[NBD_ATTR_INDEX]);
1964
1965         mutex_lock(&nbd_index_mutex);
1966
1967         msg_size = nla_total_size(nla_attr_size(sizeof(u32)) +
1968                                   nla_attr_size(sizeof(u8)));
1969         msg_size *= (index == -1) ? nbd_total_devices : 1;
1970
1971         reply = genlmsg_new(msg_size, GFP_KERNEL);
1972         if (!reply)
1973                 goto out;
1974         reply_head = genlmsg_put_reply(reply, info, &nbd_genl_family, 0,
1975                                        NBD_CMD_STATUS);
1976         if (!reply_head) {
1977                 nlmsg_free(reply);
1978                 goto out;
1979         }
1980
1981         dev_list = nla_nest_start(reply, NBD_ATTR_DEVICE_LIST);
1982         if (index == -1) {
1983                 ret = idr_for_each(&nbd_index_idr, &status_cb, reply);
1984                 if (ret) {
1985                         nlmsg_free(reply);
1986                         goto out;
1987                 }
1988         } else {
1989                 struct nbd_device *nbd;
1990                 nbd = idr_find(&nbd_index_idr, index);
1991                 if (nbd) {
1992                         ret = populate_nbd_status(nbd, reply);
1993                         if (ret) {
1994                                 nlmsg_free(reply);
1995                                 goto out;
1996                         }
1997                 }
1998         }
1999         nla_nest_end(reply, dev_list);
2000         genlmsg_end(reply, reply_head);
2001         genlmsg_reply(reply, info);
2002         ret = 0;
2003 out:
2004         mutex_unlock(&nbd_index_mutex);
2005         return ret;
2006 }
2007
2008 static void nbd_connect_reply(struct genl_info *info, int index)
2009 {
2010         struct sk_buff *skb;
2011         void *msg_head;
2012         int ret;
2013
2014         skb = genlmsg_new(nla_total_size(sizeof(u32)), GFP_KERNEL);
2015         if (!skb)
2016                 return;
2017         msg_head = genlmsg_put_reply(skb, info, &nbd_genl_family, 0,
2018                                      NBD_CMD_CONNECT);
2019         if (!msg_head) {
2020                 nlmsg_free(skb);
2021                 return;
2022         }
2023         ret = nla_put_u32(skb, NBD_ATTR_INDEX, index);
2024         if (ret) {
2025                 nlmsg_free(skb);
2026                 return;
2027         }
2028         genlmsg_end(skb, msg_head);
2029         genlmsg_reply(skb, info);
2030 }
2031
2032 static void nbd_mcast_index(int index)
2033 {
2034         struct sk_buff *skb;
2035         void *msg_head;
2036         int ret;
2037
2038         skb = genlmsg_new(nla_total_size(sizeof(u32)), GFP_KERNEL);
2039         if (!skb)
2040                 return;
2041         msg_head = genlmsg_put(skb, 0, 0, &nbd_genl_family, 0,
2042                                      NBD_CMD_LINK_DEAD);
2043         if (!msg_head) {
2044                 nlmsg_free(skb);
2045                 return;
2046         }
2047         ret = nla_put_u32(skb, NBD_ATTR_INDEX, index);
2048         if (ret) {
2049                 nlmsg_free(skb);
2050                 return;
2051         }
2052         genlmsg_end(skb, msg_head);
2053         genlmsg_multicast(&nbd_genl_family, skb, 0, 0, GFP_KERNEL);
2054 }
2055
2056 static void nbd_dead_link_work(struct work_struct *work)
2057 {
2058         struct link_dead_args *args = container_of(work, struct link_dead_args,
2059                                                    work);
2060         nbd_mcast_index(args->index);
2061         kfree(args);
2062 }
2063
2064 static int __init nbd_init(void)
2065 {
2066         int i;
2067
2068         BUILD_BUG_ON(sizeof(struct nbd_request) != 28);
2069
2070         if (max_part < 0) {
2071                 printk(KERN_ERR "nbd: max_part must be >= 0\n");
2072                 return -EINVAL;
2073         }
2074
2075         part_shift = 0;
2076         if (max_part > 0) {
2077                 part_shift = fls(max_part);
2078
2079                 /*
2080                  * Adjust max_part according to part_shift as it is exported
2081                  * to user space so that user can know the max number of
2082                  * partition kernel should be able to manage.
2083                  *
2084                  * Note that -1 is required because partition 0 is reserved
2085                  * for the whole disk.
2086                  */
2087                 max_part = (1UL << part_shift) - 1;
2088         }
2089
2090         if ((1UL << part_shift) > DISK_MAX_PARTS)
2091                 return -EINVAL;
2092
2093         if (nbds_max > 1UL << (MINORBITS - part_shift))
2094                 return -EINVAL;
2095         recv_workqueue = alloc_workqueue("knbd-recv",
2096                                          WQ_MEM_RECLAIM | WQ_HIGHPRI, 0);
2097         if (!recv_workqueue)
2098                 return -ENOMEM;
2099
2100         if (register_blkdev(NBD_MAJOR, "nbd")) {
2101                 destroy_workqueue(recv_workqueue);
2102                 return -EIO;
2103         }
2104
2105         if (genl_register_family(&nbd_genl_family)) {
2106                 unregister_blkdev(NBD_MAJOR, "nbd");
2107                 destroy_workqueue(recv_workqueue);
2108                 return -EINVAL;
2109         }
2110         nbd_dbg_init();
2111
2112         mutex_lock(&nbd_index_mutex);
2113         for (i = 0; i < nbds_max; i++)
2114                 nbd_dev_add(i);
2115         mutex_unlock(&nbd_index_mutex);
2116         return 0;
2117 }
2118
2119 static int nbd_exit_cb(int id, void *ptr, void *data)
2120 {
2121         struct list_head *list = (struct list_head *)data;
2122         struct nbd_device *nbd = ptr;
2123
2124         list_add_tail(&nbd->list, list);
2125         return 0;
2126 }
2127
2128 static void __exit nbd_cleanup(void)
2129 {
2130         struct nbd_device *nbd;
2131         LIST_HEAD(del_list);
2132
2133         nbd_dbg_close();
2134
2135         mutex_lock(&nbd_index_mutex);
2136         idr_for_each(&nbd_index_idr, &nbd_exit_cb, &del_list);
2137         mutex_unlock(&nbd_index_mutex);
2138
2139         while (!list_empty(&del_list)) {
2140                 nbd = list_first_entry(&del_list, struct nbd_device, list);
2141                 list_del_init(&nbd->list);
2142                 if (refcount_read(&nbd->refs) != 1)
2143                         printk(KERN_ERR "nbd: possibly leaking a device\n");
2144                 nbd_put(nbd);
2145         }
2146
2147         idr_destroy(&nbd_index_idr);
2148         genl_unregister_family(&nbd_genl_family);
2149         destroy_workqueue(recv_workqueue);
2150         unregister_blkdev(NBD_MAJOR, "nbd");
2151 }
2152
2153 module_init(nbd_init);
2154 module_exit(nbd_cleanup);
2155
2156 MODULE_DESCRIPTION("Network Block Device");
2157 MODULE_LICENSE("GPL");
2158
2159 module_param(nbds_max, int, 0444);
2160 MODULE_PARM_DESC(nbds_max, "number of network block devices to initialize (default: 16)");
2161 module_param(max_part, int, 0444);
2162 MODULE_PARM_DESC(max_part, "number of partitions per device (default: 16)");