fs/orangefs/devorangefs-req.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * (C) 2001 Clemson University and The University of Chicago
   4  *
   5  * Changes by Acxiom Corporation to add protocol version to kernel
   6  * communication, Copyright Acxiom Corporation, 2005.
   7  *
   8  * See COPYING in top-level directory.
   9  */
  10
  11 #include "protocol.h"
  12 #include "orangefs-kernel.h"
  13 #include "orangefs-dev-proto.h"
  14 #include "orangefs-bufmap.h"
  15 #include "orangefs-debugfs.h"
  16
  17 #include <linux/debugfs.h>
  18 #include <linux/slab.h>
  19
  20 /* this file implements the /dev/pvfs2-req device node */
  21
  22 uint32_t orangefs_userspace_version;
  23
  24 static int open_access_count;
  25
  26 static DEFINE_MUTEX(devreq_mutex);
  27
  28 #define DUMP_DEVICE_ERROR()                                                   \
  29 do {                                                                          \
  30         gossip_err("*****************************************************\n");\
  31         gossip_err("ORANGEFS Device Error:  You cannot open the device file ");  \
  32         gossip_err("\n/dev/%s more than once.  Please make sure that\nthere " \
  33                    "are no ", ORANGEFS_REQDEVICE_NAME);                          \
  34         gossip_err("instances of a program using this device\ncurrently "     \
  35                    "running. (You must verify this!)\n");                     \
  36         gossip_err("For example, you can use the lsof program as follows:\n");\
  37         gossip_err("'lsof | grep %s' (run this as root)\n",                   \
  38                    ORANGEFS_REQDEVICE_NAME);                                     \
  39         gossip_err("  open_access_count = %d\n", open_access_count);          \
  40         gossip_err("*****************************************************\n");\
  41 } while (0)
  42
  43 static int hash_func(__u64 tag, int table_size)
  44 {
  45         return do_div(tag, (unsigned int)table_size);
  46 }
  47
  48 static void orangefs_devreq_add_op(struct orangefs_kernel_op_s *op)
  49 {
  50         int index = hash_func(op->tag, hash_table_size);
  51
  52         list_add_tail(&op->list, &orangefs_htable_ops_in_progress[index]);
  53 }
  54
  55 /*
  56  * find the op with this tag and remove it from the in progress
  57  * hash table.
  58  */
  59 static struct orangefs_kernel_op_s *orangefs_devreq_remove_op(__u64 tag)
  60 {
  61         struct orangefs_kernel_op_s *op, *next;
  62         int index;
  63
  64         index = hash_func(tag, hash_table_size);
  65
  66         spin_lock(&orangefs_htable_ops_in_progress_lock);
  67         list_for_each_entry_safe(op,
  68                                  next,
  69                                  &orangefs_htable_ops_in_progress[index],
  70                                  list) {
  71                 if (op->tag == tag && !op_state_purged(op) &&
  72                     !op_state_given_up(op)) {
  73                         list_del_init(&op->list);
  74                         spin_unlock(&orangefs_htable_ops_in_progress_lock);
  75                         return op;
  76                 }
  77         }
  78
  79         spin_unlock(&orangefs_htable_ops_in_progress_lock);
  80         return NULL;
  81 }
  82
  83 /* Returns whether any FS are still pending remounted */
  84 static int mark_all_pending_mounts(void)
  85 {
  86         int unmounted = 1;
  87         struct orangefs_sb_info_s *orangefs_sb = NULL;
  88
  89         spin_lock(&orangefs_superblocks_lock);
  90         list_for_each_entry(orangefs_sb, &orangefs_superblocks, list) {
  91                 /* All of these file system require a remount */
  92                 orangefs_sb->mount_pending = 1;
  93                 unmounted = 0;
  94         }
  95         spin_unlock(&orangefs_superblocks_lock);
  96         return unmounted;
  97 }
  98
  99 /*
 100  * Determine if a given file system needs to be remounted or not
 101  *  Returns -1 on error
 102  *           0 if already mounted
 103  *           1 if needs remount
 104  */
 105 static int fs_mount_pending(__s32 fsid)
 106 {
 107         int mount_pending = -1;
 108         struct orangefs_sb_info_s *orangefs_sb = NULL;
 109
 110         spin_lock(&orangefs_superblocks_lock);
 111         list_for_each_entry(orangefs_sb, &orangefs_superblocks, list) {
 112                 if (orangefs_sb->fs_id == fsid) {
 113                         mount_pending = orangefs_sb->mount_pending;
 114                         break;
 115                 }
 116         }
 117         spin_unlock(&orangefs_superblocks_lock);
 118         return mount_pending;
 119 }
 120
 121 static int orangefs_devreq_open(struct inode *inode, struct file *file)
 122 {
 123         int ret = -EINVAL;
 124
 125         /* in order to ensure that the filesystem driver sees correct UIDs */
 126         if (file->f_cred->user_ns != &init_user_ns) {
 127                 gossip_err("%s: device cannot be opened outside init_user_ns\n",
 128                            __func__);
 129                 goto out;
 130         }
 131
 132         if (!(file->f_flags & O_NONBLOCK)) {
 133                 gossip_err("%s: device cannot be opened in blocking mode\n",
 134                            __func__);
 135                 goto out;
 136         }
 137         ret = -EACCES;
 138         gossip_debug(GOSSIP_DEV_DEBUG, "client-core: opening device\n");
 139         mutex_lock(&devreq_mutex);
 140
 141         if (open_access_count == 0) {
 142                 open_access_count = 1;
 143                 ret = 0;
 144         } else {
 145                 DUMP_DEVICE_ERROR();
 146         }
 147         mutex_unlock(&devreq_mutex);
 148
 149 out:
 150
 151         gossip_debug(GOSSIP_DEV_DEBUG,
 152                      "pvfs2-client-core: open device complete (ret = %d)\n",
 153                      ret);
 154         return ret;
 155 }
 156
 157 /* Function for read() callers into the device */
 158 static ssize_t orangefs_devreq_read(struct file *file,
 159                                  char __user *buf,
 160                                  size_t count, loff_t *offset)
 161 {
 162         struct orangefs_kernel_op_s *op, *temp;
 163         __s32 proto_ver = ORANGEFS_KERNEL_PROTO_VERSION;
 164         static __s32 magic = ORANGEFS_DEVREQ_MAGIC;
 165         struct orangefs_kernel_op_s *cur_op = NULL;
 166         unsigned long ret;
 167
 168         /* We do not support blocking IO. */
 169         if (!(file->f_flags & O_NONBLOCK)) {
 170                 gossip_err("%s: blocking read from client-core.\n",
 171                            __func__);
 172                 return -EINVAL;
 173         }
 174
 175         /*
 176          * The client will do an ioctl to find MAX_DEV_REQ_UPSIZE, then
 177          * always read with that size buffer.
 178          */
 179         if (count != MAX_DEV_REQ_UPSIZE) {
 180                 gossip_err("orangefs: client-core tried to read wrong size\n");
 181                 return -EINVAL;
 182         }
 183
 184         /* Check for an empty list before locking. */
 185         if (list_empty(&orangefs_request_list))
 186                 return -EAGAIN;
 187
 188 restart:
 189         /* Get next op (if any) from top of list. */
 190         spin_lock(&orangefs_request_list_lock);
 191         list_for_each_entry_safe(op, temp, &orangefs_request_list, list) {
 192                 __s32 fsid;
 193                 /* This lock is held past the end of the loop when we break. */
 194                 spin_lock(&op->lock);
 195                 if (unlikely(op_state_purged(op) || op_state_given_up(op))) {
 196                         spin_unlock(&op->lock);
 197                         continue;
 198                 }
 199
 200                 fsid = fsid_of_op(op);
 201                 if (fsid != ORANGEFS_FS_ID_NULL) {
 202                         int ret;
 203                         /* Skip ops whose filesystem needs to be mounted. */
 204                         ret = fs_mount_pending(fsid);
 205                         if (ret == 1) {
 206                                 gossip_debug(GOSSIP_DEV_DEBUG,
 207                                     "%s: mount pending, skipping op tag "
 208                                     "%llu %s\n",
 209                                     __func__,
 210                                     llu(op->tag),
 211                                     get_opname_string(op));
 212                                 spin_unlock(&op->lock);
 213                                 continue;
 214                         /*
 215                          * Skip ops whose filesystem we don't know about unless
 216                          * it is being mounted or unmounted.  It is possible for
 217                          * a filesystem we don't know about to be unmounted if
 218                          * it fails to mount in the kernel after userspace has
 219                          * been sent the mount request.
 220                          */
 221                         /* XXX: is there a better way to detect this? */
 222                         } else if (ret == -1 &&
 223                                    !(op->upcall.type ==
 224                                         ORANGEFS_VFS_OP_FS_MOUNT ||
 225                                      op->upcall.type ==
 226                                         ORANGEFS_VFS_OP_GETATTR ||
 227                                      op->upcall.type ==
 228                                         ORANGEFS_VFS_OP_FS_UMOUNT)) {
 229                                 gossip_debug(GOSSIP_DEV_DEBUG,
 230                                     "orangefs: skipping op tag %llu %s\n",
 231                                     llu(op->tag), get_opname_string(op));
 232                                 gossip_err(
 233                                     "orangefs: ERROR: fs_mount_pending %d\n",
 234                                     fsid);
 235                                 spin_unlock(&op->lock);
 236                                 continue;
 237                         }
 238                 }
 239                 /*
 240                  * Either this op does not pertain to a filesystem, is mounting
 241                  * a filesystem, or pertains to a mounted filesystem. Let it
 242                  * through.
 243                  */
 244                 cur_op = op;
 245                 break;
 246         }
 247
 248         /*
 249          * At this point we either have a valid op and can continue or have not
 250          * found an op and must ask the client to try again later.
 251          */
 252         if (!cur_op) {
 253                 spin_unlock(&orangefs_request_list_lock);
 254                 return -EAGAIN;
 255         }
 256
 257         gossip_debug(GOSSIP_DEV_DEBUG, "%s: reading op tag %llu %s\n",
 258                      __func__,
 259                      llu(cur_op->tag),
 260                      get_opname_string(cur_op));
 261
 262         /*
 263          * Such an op should never be on the list in the first place. If so, we
 264          * will abort.
 265          */
 266         if (op_state_in_progress(cur_op) || op_state_serviced(cur_op)) {
 267                 gossip_err("orangefs: ERROR: Current op already queued.\n");
 268                 list_del_init(&cur_op->list);
 269                 spin_unlock(&cur_op->lock);
 270                 spin_unlock(&orangefs_request_list_lock);
 271                 return -EAGAIN;
 272         }
 273
 274         list_del_init(&cur_op->list);
 275         spin_unlock(&orangefs_request_list_lock);
 276
 277         spin_unlock(&cur_op->lock);
 278
 279         /* Push the upcall out. */
 280         ret = copy_to_user(buf, &proto_ver, sizeof(__s32));
 281         if (ret != 0)
 282                 goto error;
 283         ret = copy_to_user(buf+sizeof(__s32), &magic, sizeof(__s32));
 284         if (ret != 0)
 285                 goto error;
 286         ret = copy_to_user(buf+2 * sizeof(__s32), &cur_op->tag, sizeof(__u64));
 287         if (ret != 0)
 288                 goto error;
 289         ret = copy_to_user(buf+2*sizeof(__s32)+sizeof(__u64), &cur_op->upcall,
 290                            sizeof(struct orangefs_upcall_s));
 291         if (ret != 0)
 292                 goto error;
 293
 294         spin_lock(&orangefs_htable_ops_in_progress_lock);
 295         spin_lock(&cur_op->lock);
 296         if (unlikely(op_state_given_up(cur_op))) {
 297                 spin_unlock(&cur_op->lock);
 298                 spin_unlock(&orangefs_htable_ops_in_progress_lock);
 299                 complete(&cur_op->waitq);
 300                 goto restart;
 301         }
 302
 303         /*
 304          * Set the operation to be in progress and move it between lists since
 305          * it has been sent to the client.
 306          */
 307         set_op_state_inprogress(cur_op);
 308         gossip_debug(GOSSIP_DEV_DEBUG,
 309                      "%s: 1 op:%s: op_state:%d: process:%s:\n",
 310                      __func__,
 311                      get_opname_string(cur_op),
 312                      cur_op->op_state,
 313                      current->comm);
 314         orangefs_devreq_add_op(cur_op);
 315         spin_unlock(&cur_op->lock);
 316         spin_unlock(&orangefs_htable_ops_in_progress_lock);
 317
 318         /* The client only asks to read one size buffer. */
 319         return MAX_DEV_REQ_UPSIZE;
 320 error:
 321         /*
 322          * We were unable to copy the op data to the client. Put the op back in
 323          * list. If client has crashed, the op will be purged later when the
 324          * device is released.
 325          */
 326         gossip_err("orangefs: Failed to copy data to user space\n");
 327         spin_lock(&orangefs_request_list_lock);
 328         spin_lock(&cur_op->lock);
 329         if (likely(!op_state_given_up(cur_op))) {
 330                 set_op_state_waiting(cur_op);
 331                 gossip_debug(GOSSIP_DEV_DEBUG,
 332                              "%s: 2 op:%s: op_state:%d: process:%s:\n",
 333                              __func__,
 334                              get_opname_string(cur_op),
 335                              cur_op->op_state,
 336                              current->comm);
 337                 list_add(&cur_op->list, &orangefs_request_list);
 338                 spin_unlock(&cur_op->lock);
 339         } else {
 340                 spin_unlock(&cur_op->lock);
 341                 complete(&cur_op->waitq);
 342         }
 343         spin_unlock(&orangefs_request_list_lock);
 344         return -EFAULT;
 345 }
 346
 347 /*
 348  * Function for writev() callers into the device.
 349  *
 350  * Userspace should have written:
 351  *  - __u32 version
 352  *  - __u32 magic
 353  *  - __u64 tag
 354  *  - struct orangefs_downcall_s
 355  *  - trailer buffer (in the case of READDIR operations)
 356  */
 357 static ssize_t orangefs_devreq_write_iter(struct kiocb *iocb,
 358                                       struct iov_iter *iter)
 359 {
 360         ssize_t ret;
 361         struct orangefs_kernel_op_s *op = NULL;
 362         struct {
 363                 __u32 version;
 364                 __u32 magic;
 365                 __u64 tag;
 366         } head;
 367         int total = ret = iov_iter_count(iter);
 368         int downcall_size = sizeof(struct orangefs_downcall_s);
 369         int head_size = sizeof(head);
 370
 371         gossip_debug(GOSSIP_DEV_DEBUG, "%s: total:%d: ret:%zd:\n",
 372                      __func__,
 373                      total,
 374                      ret);
 375
 376         if (total < MAX_DEV_REQ_DOWNSIZE) {
 377                 gossip_err("%s: total:%d: must be at least:%u:\n",
 378                            __func__,
 379                            total,
 380                            (unsigned int) MAX_DEV_REQ_DOWNSIZE);
 381                 return -EFAULT;
 382         }
 383
 384         if (!copy_from_iter_full(&head, head_size, iter)) {
 385                 gossip_err("%s: failed to copy head.\n", __func__);
 386                 return -EFAULT;
 387         }
 388
 389         if (head.version < ORANGEFS_MINIMUM_USERSPACE_VERSION) {
 390                 gossip_err("%s: userspace claims version"
 391                            "%d, minimum version required: %d.\n",
 392                            __func__,
 393                            head.version,
 394                            ORANGEFS_MINIMUM_USERSPACE_VERSION);
 395                 return -EPROTO;
 396         }
 397
 398         if (head.magic != ORANGEFS_DEVREQ_MAGIC) {
 399                 gossip_err("Error: Device magic number does not match.\n");
 400                 return -EPROTO;
 401         }
 402
 403         if (!orangefs_userspace_version) {
 404                 orangefs_userspace_version = head.version;
 405         } else if (orangefs_userspace_version != head.version) {
 406                 gossip_err("Error: userspace version changes\n");
 407                 return -EPROTO;
 408         }
 409
 410         /* remove the op from the in progress hash table */
 411         op = orangefs_devreq_remove_op(head.tag);
 412         if (!op) {
 413                 gossip_debug(GOSSIP_DEV_DEBUG,
 414                              "%s: No one's waiting for tag %llu\n",
 415                              __func__, llu(head.tag));
 416                 return ret;
 417         }
 418
 419         if (!copy_from_iter_full(&op->downcall, downcall_size, iter)) {
 420                 gossip_err("%s: failed to copy downcall.\n", __func__);
 421                 goto Efault;
 422         }
 423
 424         if (op->downcall.status)
 425                 goto wakeup;
 426
 427         /*
 428          * We've successfully peeled off the head and the downcall.
 429          * Something has gone awry if total doesn't equal the
 430          * sum of head_size, downcall_size and trailer_size.
 431          */
 432         if ((head_size + downcall_size + op->downcall.trailer_size) != total) {
 433                 gossip_err("%s: funky write, head_size:%d"
 434                            ": downcall_size:%d: trailer_size:%lld"
 435                            ": total size:%d:\n",
 436                            __func__,
 437                            head_size,
 438                            downcall_size,
 439                            op->downcall.trailer_size,
 440                            total);
 441                 goto Efault;
 442         }
 443
 444         /* Only READDIR operations should have trailers. */
 445         if ((op->downcall.type != ORANGEFS_VFS_OP_READDIR) &&
 446             (op->downcall.trailer_size != 0)) {
 447                 gossip_err("%s: %x operation with trailer.",
 448                            __func__,
 449                            op->downcall.type);
 450                 goto Efault;
 451         }
 452
 453         /* READDIR operations should always have trailers. */
 454         if ((op->downcall.type == ORANGEFS_VFS_OP_READDIR) &&
 455             (op->downcall.trailer_size == 0)) {
 456                 gossip_err("%s: %x operation with no trailer.",
 457                            __func__,
 458                            op->downcall.type);
 459                 goto Efault;
 460         }
 461
 462         if (op->downcall.type != ORANGEFS_VFS_OP_READDIR)
 463                 goto wakeup;
 464
 465         op->downcall.trailer_buf = vmalloc(op->downcall.trailer_size);
 466         if (!op->downcall.trailer_buf)
 467                 goto Enomem;
 468
 469         memset(op->downcall.trailer_buf, 0, op->downcall.trailer_size);
 470         if (!copy_from_iter_full(op->downcall.trailer_buf,
 471                                  op->downcall.trailer_size, iter)) {
 472                 gossip_err("%s: failed to copy trailer.\n", __func__);
 473                 vfree(op->downcall.trailer_buf);
 474                 goto Efault;
 475         }
 476
 477 wakeup:
 478         /*
 479          * Return to vfs waitqueue, and back to service_operation
 480          * through wait_for_matching_downcall.
 481          */
 482         spin_lock(&op->lock);
 483         if (unlikely(op_is_cancel(op))) {
 484                 spin_unlock(&op->lock);
 485                 put_cancel(op);
 486         } else if (unlikely(op_state_given_up(op))) {
 487                 spin_unlock(&op->lock);
 488                 complete(&op->waitq);
 489         } else {
 490                 set_op_state_serviced(op);
 491                 gossip_debug(GOSSIP_DEV_DEBUG,
 492                              "%s: op:%s: op_state:%d: process:%s:\n",
 493                              __func__,
 494                              get_opname_string(op),
 495                              op->op_state,
 496                              current->comm);
 497                 spin_unlock(&op->lock);
 498         }
 499         return ret;
 500
 501 Efault:
 502         op->downcall.status = -(ORANGEFS_ERROR_BIT | 9);
 503         ret = -EFAULT;
 504         goto wakeup;
 505
 506 Enomem:
 507         op->downcall.status = -(ORANGEFS_ERROR_BIT | 8);
 508         ret = -ENOMEM;
 509         goto wakeup;
 510 }
 511
 512 /*
 513  * NOTE: gets called when the last reference to this device is dropped.
 514  * Using the open_access_count variable, we enforce a reference count
 515  * on this file so that it can be opened by only one process at a time.
 516  * the devreq_mutex is used to make sure all i/o has completed
 517  * before we call orangefs_bufmap_finalize, and similar such tricky
 518  * situations
 519  */
 520 static int orangefs_devreq_release(struct inode *inode, struct file *file)
 521 {
 522         int unmounted = 0;
 523
 524         gossip_debug(GOSSIP_DEV_DEBUG,
 525                      "%s:pvfs2-client-core: exiting, closing device\n",
 526                      __func__);
 527
 528         mutex_lock(&devreq_mutex);
 529         orangefs_bufmap_finalize();
 530
 531         open_access_count = -1;
 532
 533         unmounted = mark_all_pending_mounts();
 534         gossip_debug(GOSSIP_DEV_DEBUG, "ORANGEFS Device Close: Filesystem(s) %s\n",
 535                      (unmounted ? "UNMOUNTED" : "MOUNTED"));
 536
 537         purge_waiting_ops();
 538         purge_inprogress_ops();
 539
 540         orangefs_bufmap_run_down();
 541
 542         gossip_debug(GOSSIP_DEV_DEBUG,
 543                      "pvfs2-client-core: device close complete\n");
 544         open_access_count = 0;
 545         orangefs_userspace_version = 0;
 546         mutex_unlock(&devreq_mutex);
 547         return 0;
 548 }
 549
 550 int is_daemon_in_service(void)
 551 {
 552         int in_service;
 553
 554         /*
 555          * What this function does is checks if client-core is alive
 556          * based on the access count we maintain on the device.
 557          */
 558         mutex_lock(&devreq_mutex);
 559         in_service = open_access_count == 1 ? 0 : -EIO;
 560         mutex_unlock(&devreq_mutex);
 561         return in_service;
 562 }
 563
 564 bool __is_daemon_in_service(void)
 565 {
 566         return open_access_count == 1;
 567 }
 568
 569 static inline long check_ioctl_command(unsigned int command)
 570 {
 571         /* Check for valid ioctl codes */
 572         if (_IOC_TYPE(command) != ORANGEFS_DEV_MAGIC) {
 573                 gossip_err("device ioctl magic numbers don't match! Did you rebuild pvfs2-client-core/libpvfs2? [cmd %x, magic %x != %x]\n",
 574                         command,
 575                         _IOC_TYPE(command),
 576                         ORANGEFS_DEV_MAGIC);
 577                 return -EINVAL;
 578         }
 579         /* and valid ioctl commands */
 580         if (_IOC_NR(command) >= ORANGEFS_DEV_MAXNR || _IOC_NR(command) <= 0) {
 581                 gossip_err("Invalid ioctl command number [%d >= %d]\n",
 582                            _IOC_NR(command), ORANGEFS_DEV_MAXNR);
 583                 return -ENOIOCTLCMD;
 584         }
 585         return 0;
 586 }
 587
 588 static long dispatch_ioctl_command(unsigned int command, unsigned long arg)
 589 {
 590         static __s32 magic = ORANGEFS_DEVREQ_MAGIC;
 591         static __s32 max_up_size = MAX_DEV_REQ_UPSIZE;
 592         static __s32 max_down_size = MAX_DEV_REQ_DOWNSIZE;
 593         struct ORANGEFS_dev_map_desc user_desc;
 594         int ret = 0;
 595         int upstream_kmod = 1;
 596         struct orangefs_sb_info_s *orangefs_sb;
 597
 598         /* mtmoore: add locking here */
 599
 600         switch (command) {
 601         case ORANGEFS_DEV_GET_MAGIC:
 602                 return ((put_user(magic, (__s32 __user *) arg) == -EFAULT) ?
 603                         -EIO :
 604                         0);
 605         case ORANGEFS_DEV_GET_MAX_UPSIZE:
 606                 return ((put_user(max_up_size,
 607                                   (__s32 __user *) arg) == -EFAULT) ?
 608                                         -EIO :
 609                                         0);
 610         case ORANGEFS_DEV_GET_MAX_DOWNSIZE:
 611                 return ((put_user(max_down_size,
 612                                   (__s32 __user *) arg) == -EFAULT) ?
 613                                         -EIO :
 614                                         0);
 615         case ORANGEFS_DEV_MAP:
 616                 ret = copy_from_user(&user_desc,
 617                                      (struct ORANGEFS_dev_map_desc __user *)
 618                                      arg,
 619                                      sizeof(struct ORANGEFS_dev_map_desc));
 620                 /* WTF -EIO and not -EFAULT? */
 621                 return ret ? -EIO : orangefs_bufmap_initialize(&user_desc);
 622         case ORANGEFS_DEV_REMOUNT_ALL:
 623                 gossip_debug(GOSSIP_DEV_DEBUG,
 624                              "%s: got ORANGEFS_DEV_REMOUNT_ALL\n",
 625                              __func__);
 626
 627                 /*
 628                  * remount all mounted orangefs volumes to regain the lost
 629                  * dynamic mount tables (if any) -- NOTE: this is done
 630                  * without keeping the superblock list locked due to the
 631                  * upcall/downcall waiting.  also, the request mutex is
 632                  * used to ensure that no operations will be serviced until
 633                  * all of the remounts are serviced (to avoid ops between
 634                  * mounts to fail)
 635                  */
 636                 ret = mutex_lock_interruptible(&orangefs_request_mutex);
 637                 if (ret < 0)
 638                         return ret;
 639                 gossip_debug(GOSSIP_DEV_DEBUG,
 640                              "%s: priority remount in progress\n",
 641                              __func__);
 642                 spin_lock(&orangefs_superblocks_lock);
 643                 list_for_each_entry(orangefs_sb, &orangefs_superblocks, list) {
 644                         /*
 645                          * We have to drop the spinlock, so entries can be
 646                          * removed.  They can't be freed, though, so we just
 647                          * keep the forward pointers and zero the back ones -
 648                          * that way we can get to the rest of the list.
 649                          */
 650                         if (!orangefs_sb->list.prev)
 651                                 continue;
 652                         gossip_debug(GOSSIP_DEV_DEBUG,
 653                                      "%s: Remounting SB %p\n",
 654                                      __func__,
 655                                      orangefs_sb);
 656
 657                         spin_unlock(&orangefs_superblocks_lock);
 658                         ret = orangefs_remount(orangefs_sb);
 659                         spin_lock(&orangefs_superblocks_lock);
 660                         if (ret) {
 661                                 gossip_debug(GOSSIP_DEV_DEBUG,
 662                                              "SB %p remount failed\n",
 663                                              orangefs_sb);
 664                                 break;
 665                         }
 666                 }
 667                 spin_unlock(&orangefs_superblocks_lock);
 668                 gossip_debug(GOSSIP_DEV_DEBUG,
 669                              "%s: priority remount complete\n",
 670                              __func__);
 671                 mutex_unlock(&orangefs_request_mutex);
 672                 return ret;
 673
 674         case ORANGEFS_DEV_UPSTREAM:
 675                 ret = copy_to_user((void __user *)arg,
 676                                     &upstream_kmod,
 677                                     sizeof(upstream_kmod));
 678
 679                 if (ret != 0)
 680                         return -EIO;
 681                 else
 682                         return ret;
 683
 684         case ORANGEFS_DEV_CLIENT_MASK:
 685                 return orangefs_debugfs_new_client_mask((void __user *)arg);
 686         case ORANGEFS_DEV_CLIENT_STRING:
 687                 return orangefs_debugfs_new_client_string((void __user *)arg);
 688         case ORANGEFS_DEV_DEBUG:
 689                 return orangefs_debugfs_new_debug((void __user *)arg);
 690         default:
 691                 return -ENOIOCTLCMD;
 692         }
 693         return -ENOIOCTLCMD;
 694 }
 695
 696 static long orangefs_devreq_ioctl(struct file *file,
 697                                unsigned int command, unsigned long arg)
 698 {
 699         long ret;
 700
 701         /* Check for properly constructed commands */
 702         ret = check_ioctl_command(command);
 703         if (ret < 0)
 704                 return (int)ret;
 705
 706         return (int)dispatch_ioctl_command(command, arg);
 707 }
 708
 709 #ifdef CONFIG_COMPAT            /* CONFIG_COMPAT is in .config */
 710
 711 /*  Compat structure for the ORANGEFS_DEV_MAP ioctl */
 712 struct ORANGEFS_dev_map_desc32 {
 713         compat_uptr_t ptr;
 714         __s32 total_size;
 715         __s32 size;
 716         __s32 count;
 717 };
 718
 719 static unsigned long translate_dev_map26(unsigned long args, long *error)
 720 {
 721         struct ORANGEFS_dev_map_desc32 __user *p32 = (void __user *)args;
 722         /*
 723          * Depending on the architecture, allocate some space on the
 724          * user-call-stack based on our expected layout.
 725          */
 726         struct ORANGEFS_dev_map_desc __user *p =
 727             compat_alloc_user_space(sizeof(*p));
 728         compat_uptr_t addr;
 729
 730         *error = 0;
 731         /* get the ptr from the 32 bit user-space */
 732         if (get_user(addr, &p32->ptr))
 733                 goto err;
 734         /* try to put that into a 64-bit layout */
 735         if (put_user(compat_ptr(addr), &p->ptr))
 736                 goto err;
 737         /* copy the remaining fields */
 738         if (copy_in_user(&p->total_size, &p32->total_size, sizeof(__s32)))
 739                 goto err;
 740         if (copy_in_user(&p->size, &p32->size, sizeof(__s32)))
 741                 goto err;
 742         if (copy_in_user(&p->count, &p32->count, sizeof(__s32)))
 743                 goto err;
 744         return (unsigned long)p;
 745 err:
 746         *error = -EFAULT;
 747         return 0;
 748 }
 749
 750 /*
 751  * 32 bit user-space apps' ioctl handlers when kernel modules
 752  * is compiled as a 64 bit one
 753  */
 754 static long orangefs_devreq_compat_ioctl(struct file *filp, unsigned int cmd,
 755                                       unsigned long args)
 756 {
 757         long ret;
 758         unsigned long arg = args;
 759
 760         /* Check for properly constructed commands */
 761         ret = check_ioctl_command(cmd);
 762         if (ret < 0)
 763                 return ret;
 764         if (cmd == ORANGEFS_DEV_MAP) {
 765                 /*
 766                  * convert the arguments to what we expect internally
 767                  * in kernel space
 768                  */
 769                 arg = translate_dev_map26(args, &ret);
 770                 if (ret < 0) {
 771                         gossip_err("Could not translate dev map\n");
 772                         return ret;
 773                 }
 774         }
 775         /* no other ioctl requires translation */
 776         return dispatch_ioctl_command(cmd, arg);
 777 }
 778
 779 #endif /* CONFIG_COMPAT is in .config */
 780
 781 /* the assigned character device major number */
 782 static int orangefs_dev_major;
 783
 784 /*
 785  * Initialize orangefs device specific state:
 786  * Must be called at module load time only
 787  */
 788 int orangefs_dev_init(void)
 789 {
 790         /* register orangefs-req device  */
 791         orangefs_dev_major = register_chrdev(0,
 792                                           ORANGEFS_REQDEVICE_NAME,
 793                                           &orangefs_devreq_file_operations);
 794         if (orangefs_dev_major < 0) {
 795                 gossip_debug(GOSSIP_DEV_DEBUG,
 796                              "Failed to register /dev/%s (error %d)\n",
 797                              ORANGEFS_REQDEVICE_NAME, orangefs_dev_major);
 798                 return orangefs_dev_major;
 799         }
 800
 801         gossip_debug(GOSSIP_DEV_DEBUG,
 802                      "*** /dev/%s character device registered ***\n",
 803                      ORANGEFS_REQDEVICE_NAME);
 804         gossip_debug(GOSSIP_DEV_DEBUG, "'mknod /dev/%s c %d 0'.\n",
 805                      ORANGEFS_REQDEVICE_NAME, orangefs_dev_major);
 806         return 0;
 807 }
 808
 809 void orangefs_dev_cleanup(void)
 810 {
 811         unregister_chrdev(orangefs_dev_major, ORANGEFS_REQDEVICE_NAME);
 812         gossip_debug(GOSSIP_DEV_DEBUG,
 813                      "*** /dev/%s character device unregistered ***\n",
 814                      ORANGEFS_REQDEVICE_NAME);
 815 }
 816
 817 static unsigned int orangefs_devreq_poll(struct file *file,
 818                                       struct poll_table_struct *poll_table)
 819 {
 820         int poll_revent_mask = 0;
 821
 822         poll_wait(file, &orangefs_request_list_waitq, poll_table);
 823
 824         if (!list_empty(&orangefs_request_list))
 825                 poll_revent_mask |= POLL_IN;
 826         return poll_revent_mask;
 827 }
 828
 829 const struct file_operations orangefs_devreq_file_operations = {
 830         .owner = THIS_MODULE,
 831         .read = orangefs_devreq_read,
 832         .write_iter = orangefs_devreq_write_iter,
 833         .open = orangefs_devreq_open,
 834         .release = orangefs_devreq_release,
 835         .unlocked_ioctl = orangefs_devreq_ioctl,
 836
 837 #ifdef CONFIG_COMPAT            /* CONFIG_COMPAT is in .config */
 838         .compat_ioctl = orangefs_devreq_compat_ioctl,
 839 #endif
 840         .poll = orangefs_devreq_poll
 841 };