lustre/ofd/ofd_access_log.c

   1 #include <linux/cdev.h>
   2 #include <linux/circ_buf.h>
   3 #include <linux/device.h>
   4 #include <linux/fs.h>
   5 #include <linux/kernel.h>
   6 #include <linux/miscdevice.h>
   7 #include <linux/module.h>
   8 #include <linux/poll.h>
   9 #include <linux/slab.h>
  10 #include <linux/types.h>
  11 #include <linux/uaccess.h>
  12 #include <uapi/linux/lustre/lustre_idl.h>
  13 #include <uapi/linux/lustre/lustre_access_log.h>
  14 #include "ofd_internal.h"
  15
  16 /* OFD access logs: OST (OFD) RPC handlers log accesses by FID and
  17  * PFID which are read from userspace through character device files
  18  * (/dev/lustre-access-log/scratch-OST0000). Accesses are described by
  19  * struct ofd_access_entry_v1. The char device implements read()
  20  * (blocking and nonblocking) and poll(), along with an ioctl that
  21  * returns diagnostic information on an oal device.
  22  *
  23  * A control device (/dev/lustre-access-log/control) supports an ioctl()
  24  * plus poll() method to for oal discovery. See uses of
  25  * oal_control_event_count and oal_control_wait_queue for details.
  26  *
  27  * oal log size and entry size are restricted to powers of 2 to
  28  * support circ_buf methods. See Documentation/core-api/circular-buffers.rst
  29  * in the linux tree for more information.
  30  *
  31  * The associated struct device (*oal_device) owns the oal. The
  32  * release() method of oal_device frees the oal and releases its
  33  * minor. This may seem slightly more complicated than necessary but
  34  * it allows the OST to be unmounted while the oal still has open file
  35  * descriptors.
  36  */
  37
  38 enum {
  39         OAL_DEV_COUNT = 1 << MINORBITS,
  40 };
  41
  42 struct ofd_access_log {
  43         char oal_name[128]; /* lustre-OST0000 */
  44         struct device oal_device;
  45         struct cdev oal_cdev;
  46         struct rw_semaphore oal_buf_list_sem;
  47         struct list_head oal_circ_buf_list;
  48         unsigned int oal_is_closed;
  49         unsigned int oal_log_size;
  50         unsigned int oal_entry_size;
  51 };
  52
  53 struct oal_circ_buf {
  54         struct list_head ocb_list;
  55         spinlock_t ocb_write_lock;
  56         spinlock_t ocb_read_lock;
  57         struct ofd_access_log *ocb_access_log;
  58         __u32 ocb_filter;
  59         wait_queue_head_t ocb_read_wait_queue;
  60         unsigned int ocb_drop_count;
  61         struct circ_buf ocb_circ;
  62 };
  63
  64 static atomic_t oal_control_event_count = ATOMIC_INIT(0);
  65 static DECLARE_WAIT_QUEUE_HEAD(oal_control_wait_queue);
  66
  67 static struct class *oal_log_class;
  68 static unsigned int oal_log_major;
  69 static DEFINE_IDR(oal_log_minor_idr); /* TODO Use ida instead. */
  70 static DEFINE_SPINLOCK(oal_log_minor_lock);
  71
  72 bool ofd_access_log_size_is_valid(unsigned int size)
  73 {
  74         const unsigned int size_min = 2 * sizeof(struct ofd_access_entry_v1);
  75         const unsigned int size_max = 1U << 30;
  76
  77         if (size == 0)
  78                 return true;
  79
  80         return is_power_of_2(size) && size_min <= size && size <= size_max;
  81 }
  82
  83 static void oal_control_event_inc(void)
  84 {
  85         atomic_inc(&oal_control_event_count);
  86         wake_up(&oal_control_wait_queue);
  87 }
  88
  89 static int oal_log_minor_alloc(int *pminor)
  90 {
  91         void *OAL_LOG_MINOR_ALLOCED = (void *)-1;
  92         int minor;
  93
  94         idr_preload(GFP_KERNEL);
  95         spin_lock(&oal_log_minor_lock);
  96         minor = idr_alloc(&oal_log_minor_idr, OAL_LOG_MINOR_ALLOCED, 0,
  97                         OAL_DEV_COUNT, GFP_NOWAIT);
  98         spin_unlock(&oal_log_minor_lock);
  99         idr_preload_end();
 100
 101         if (minor < 0)
 102                 return minor;
 103
 104         *pminor = minor;
 105
 106         return 0;
 107 }
 108
 109 static void oal_log_minor_free(int minor)
 110 {
 111         spin_lock(&oal_log_minor_lock);
 112         idr_remove(&oal_log_minor_idr, minor);
 113         spin_unlock(&oal_log_minor_lock);
 114 }
 115
 116 static bool oal_is_empty(struct oal_circ_buf *ocb)
 117 {
 118         struct ofd_access_log *oal = ocb->ocb_access_log;
 119
 120         return CIRC_CNT(ocb->ocb_circ.head,
 121                         ocb->ocb_circ.tail,
 122                         oal->oal_log_size) < oal->oal_entry_size;
 123 }
 124
 125 static ssize_t oal_write_entry(struct oal_circ_buf *ocb,
 126                         const void *entry, size_t entry_size)
 127 {
 128         struct ofd_access_log *oal = ocb->ocb_access_log;
 129         struct circ_buf *circ = &ocb->ocb_circ;
 130         unsigned int head;
 131         unsigned int tail;
 132         ssize_t rc;
 133
 134         if (entry_size != oal->oal_entry_size)
 135                 return -EINVAL;
 136
 137         spin_lock(&ocb->ocb_write_lock);
 138         head = circ->head;
 139         tail = READ_ONCE(circ->tail);
 140
 141         /* CIRC_SPACE() return space available, 0..oal_log_size -
 142          * 1. It always leaves one free char, since a completely full
 143          * buffer would have head == tail, which is the same as empty. */
 144         if (CIRC_SPACE(head, tail, oal->oal_log_size) < oal->oal_entry_size) {
 145                 ocb->ocb_drop_count++;
 146                 rc = -EAGAIN;
 147                 goto out_write_lock;
 148         }
 149
 150         memcpy(&circ->buf[head], entry, entry_size);
 151         rc = entry_size;
 152
 153         /* Ensure the entry is stored before we update the head. */
 154         smp_store_release(&circ->head,
 155                         (head + oal->oal_entry_size) & (oal->oal_log_size - 1));
 156
 157         wake_up(&ocb->ocb_read_wait_queue);
 158 out_write_lock:
 159         spin_unlock(&ocb->ocb_write_lock);
 160
 161         return rc;
 162 }
 163
 164 /* Read one entry from the log and return its size. Non-blocking.
 165  * When the log is empty we return -EAGAIN if the OST is still mounted
 166  * and 0 otherwise.
 167  */
 168 static ssize_t oal_read_entry(struct oal_circ_buf *ocb,
 169                         void *entry_buf, size_t entry_buf_size)
 170 {
 171         struct ofd_access_log *oal = ocb->ocb_access_log;
 172         struct circ_buf *circ = &ocb->ocb_circ;
 173         unsigned int head;
 174         unsigned int tail;
 175         ssize_t rc;
 176
 177         /* XXX This method may silently truncate entries when
 178          * entry_buf_size is less than oal_entry_size. But that's OK
 179          * because you know what you are doing. */
 180         spin_lock(&ocb->ocb_read_lock);
 181
 182         /* Memory barrier usage follows circular-buffers.txt. */
 183         head = smp_load_acquire(&circ->head);
 184         tail = circ->tail;
 185
 186         if (!CIRC_CNT(head, tail, oal->oal_log_size)) {
 187                 rc = oal->oal_is_closed ? 0 : -EAGAIN;
 188                 goto out_read_lock;
 189         }
 190
 191         BUG_ON(CIRC_CNT(head, tail, oal->oal_log_size) < oal->oal_entry_size);
 192
 193         /* Read index before reading contents at that index. */
 194         smp_read_barrier_depends();
 195
 196         /* Extract one entry from the buffer. */
 197         rc = min_t(size_t, oal->oal_entry_size, entry_buf_size);
 198         memcpy(entry_buf, &circ->buf[tail], rc);
 199
 200         /* Memory barrier usage follows circular-buffers.txt. */
 201         smp_store_release(&circ->tail,
 202                         (tail + oal->oal_entry_size) & (oal->oal_log_size - 1));
 203
 204 out_read_lock:
 205         spin_unlock(&ocb->ocb_read_lock);
 206
 207         return rc;
 208 }
 209
 210 static int oal_file_open(struct inode *inode, struct file *filp)
 211 {
 212         struct ofd_access_log *oal;
 213         struct oal_circ_buf *ocb;
 214
 215         oal = container_of(inode->i_cdev, struct ofd_access_log, oal_cdev);
 216
 217         ocb = kzalloc(sizeof(*ocb), GFP_KERNEL);
 218         if (!ocb)
 219                 return -ENOMEM;
 220         ocb->ocb_circ.buf = vmalloc(oal->oal_log_size);
 221         if (!ocb->ocb_circ.buf) {
 222                 kfree(ocb);
 223                 return -ENOMEM;
 224         }
 225
 226         spin_lock_init(&ocb->ocb_write_lock);
 227         spin_lock_init(&ocb->ocb_read_lock);
 228         ocb->ocb_access_log = oal;
 229         init_waitqueue_head(&ocb->ocb_read_wait_queue);
 230
 231         down_write(&oal->oal_buf_list_sem);
 232         list_add(&ocb->ocb_list, &oal->oal_circ_buf_list);
 233         up_write(&oal->oal_buf_list_sem);
 234
 235         filp->private_data = ocb;
 236
 237         return nonseekable_open(inode, filp);
 238 }
 239
 240 /* User buffer size must be a multiple of ofd access entry size. */
 241 static ssize_t oal_file_read(struct file *filp, char __user *buf, size_t count,
 242                         loff_t *ppos)
 243 {
 244         struct oal_circ_buf *ocb = filp->private_data;
 245         struct ofd_access_log *oal = ocb->ocb_access_log;
 246         void *entry;
 247         size_t size = 0;
 248         int rc = 0;
 249
 250         if (!count)
 251                 return 0;
 252
 253         if (count & (oal->oal_entry_size - 1))
 254                 return -EINVAL;
 255
 256         entry = kzalloc(oal->oal_entry_size, GFP_KERNEL);
 257         if (!entry)
 258                 return -ENOMEM;
 259
 260         while (size < count) {
 261                 rc = oal_read_entry(ocb, entry, oal->oal_entry_size);
 262                 if (rc == -EAGAIN) {
 263                         if (filp->f_flags & O_NONBLOCK)
 264                                 break;
 265
 266                         rc = wait_event_interruptible(ocb->ocb_read_wait_queue,
 267                                 !oal_is_empty(ocb) || oal->oal_is_closed);
 268                         if (rc)
 269                                 break;
 270                 } else if (rc <= 0) {
 271                         break; /* cloed or error */
 272                 } else {
 273                         if (copy_to_user(buf, entry, oal->oal_entry_size)) {
 274                                 rc = -EFAULT;
 275                                 break;
 276                         }
 277
 278                         buf += oal->oal_entry_size;
 279                         size += oal->oal_entry_size;
 280                 }
 281         }
 282
 283         kfree(entry);
 284
 285         return size ? size : rc;
 286 }
 287
 288 /* Included for test purposes. User buffer size must be a multiple of
 289  * ofd access entry size. */
 290 static ssize_t oal_file_write(struct file *filp, const char __user *buf,
 291                         size_t count, loff_t *ppos)
 292 {
 293         struct oal_circ_buf *ocb = filp->private_data;
 294         struct ofd_access_log *oal = ocb->ocb_access_log;
 295         void *entry;
 296         size_t size = 0;
 297         ssize_t rc = 0;
 298
 299         if (!count)
 300                 return 0;
 301
 302         if (count & (oal->oal_entry_size - 1))
 303                 return -EINVAL;
 304
 305         entry = kzalloc(oal->oal_entry_size, GFP_KERNEL);
 306         if (!entry)
 307                 return -ENOMEM;
 308
 309         while (size < count) {
 310                 if (copy_from_user(entry, buf, oal->oal_entry_size)) {
 311                         rc = -EFAULT;
 312                         break;
 313                 }
 314
 315                 rc = oal_write_entry(ocb, entry, oal->oal_entry_size);
 316                 if (rc <= 0)
 317                         break;
 318
 319                 buf += oal->oal_entry_size;
 320                 size += oal->oal_entry_size;
 321         }
 322
 323         kfree(entry);
 324
 325         return size > 0 ? size : rc;
 326 }
 327
 328 unsigned int oal_file_poll(struct file *filp, struct poll_table_struct *wait)
 329 {
 330         struct oal_circ_buf *ocb = filp->private_data;
 331         struct ofd_access_log *oal = ocb->ocb_access_log;
 332         unsigned int mask = 0;
 333
 334         poll_wait(filp, &ocb->ocb_read_wait_queue, wait);
 335
 336         spin_lock(&ocb->ocb_read_lock);
 337
 338         if (!oal_is_empty(ocb) || oal->oal_is_closed)
 339                 mask |= POLLIN;
 340
 341         spin_unlock(&ocb->ocb_read_lock);
 342
 343         return mask;
 344 }
 345
 346 static long oal_ioctl_info(struct oal_circ_buf *ocb, unsigned long arg)
 347 {
 348         struct ofd_access_log *oal = ocb->ocb_access_log;
 349
 350         struct lustre_access_log_info_v1 __user *lali;
 351         u32 entry_count = CIRC_CNT(ocb->ocb_circ.head,
 352                                 ocb->ocb_circ.tail,
 353                                 oal->oal_log_size) / oal->oal_entry_size;
 354         u32 entry_space = CIRC_SPACE(ocb->ocb_circ.head,
 355                                 ocb->ocb_circ.tail,
 356                                 oal->oal_log_size) / oal->oal_entry_size;
 357
 358         lali = (struct lustre_access_log_info_v1 __user *)arg;
 359         BUILD_BUG_ON(sizeof(lali->lali_name) != sizeof(oal->oal_name));
 360
 361         if (put_user(LUSTRE_ACCESS_LOG_VERSION_1, &lali->lali_version))
 362                 return -EFAULT;
 363
 364         if (put_user(LUSTRE_ACCESS_LOG_TYPE_OFD, &lali->lali_type))
 365                 return -EFAULT;
 366
 367         if (copy_to_user(lali->lali_name, oal->oal_name, sizeof(oal->oal_name)))
 368                 return -EFAULT;
 369
 370         if (put_user(oal->oal_log_size, &lali->lali_log_size))
 371                 return -EFAULT;
 372
 373         if (put_user(oal->oal_entry_size, &lali->lali_entry_size))
 374                 return -EFAULT;
 375
 376         if (put_user(ocb->ocb_circ.head, &lali->_lali_head))
 377                 return -EFAULT;
 378
 379         if (put_user(ocb->ocb_circ.tail, &lali->_lali_tail))
 380                 return -EFAULT;
 381
 382         if (put_user(entry_space, &lali->_lali_entry_space))
 383                 return -EFAULT;
 384
 385         if (put_user(entry_count, &lali->_lali_entry_count))
 386                 return -EFAULT;
 387
 388         if (put_user(ocb->ocb_drop_count, &lali->_lali_drop_count))
 389                 return -EFAULT;
 390
 391         if (put_user(oal->oal_is_closed, &lali->_lali_is_closed))
 392                 return -EFAULT;
 393
 394         return 0;
 395 }
 396
 397 static long oal_file_ioctl(struct file *filp, unsigned int cmd,
 398                         unsigned long arg)
 399 {
 400         struct oal_circ_buf *ocb = filp->private_data;
 401
 402         switch (cmd) {
 403         case LUSTRE_ACCESS_LOG_IOCTL_VERSION:
 404                 return LUSTRE_ACCESS_LOG_VERSION_1;
 405         case LUSTRE_ACCESS_LOG_IOCTL_INFO:
 406                 return oal_ioctl_info(ocb, arg);
 407         case LUSTRE_ACCESS_LOG_IOCTL_FILTER:
 408                 ocb->ocb_filter = arg;
 409                 return 0;
 410         default:
 411                 return -ENOTTY;
 412         }
 413 }
 414
 415 static int oal_file_release(struct inode *inode, struct file *filp)
 416 {
 417         struct oal_circ_buf *ocb = filp->private_data;
 418         struct ofd_access_log *oal = ocb->ocb_access_log;
 419
 420         down_write(&oal->oal_buf_list_sem);
 421         list_del(&ocb->ocb_list);
 422         up_write(&oal->oal_buf_list_sem);
 423
 424         vfree(ocb->ocb_circ.buf);
 425         kfree(ocb);
 426
 427         return 0;
 428 }
 429
 430 static const struct file_operations oal_fops = {
 431         .owner = THIS_MODULE,
 432         .open = &oal_file_open,
 433         .release = &oal_file_release,
 434         .unlocked_ioctl = &oal_file_ioctl,
 435         .read = &oal_file_read,
 436         .write = &oal_file_write,
 437         .poll = &oal_file_poll,
 438         .llseek = &no_llseek,
 439 };
 440
 441 static void oal_device_release(struct device *dev)
 442 {
 443         struct ofd_access_log *oal = dev_get_drvdata(dev);
 444
 445         oal_log_minor_free(MINOR(oal->oal_device.devt));
 446         BUG_ON(!list_empty(&oal->oal_circ_buf_list));
 447         kfree(oal);
 448 }
 449
 450 struct ofd_access_log *ofd_access_log_create(const char *ofd_name, size_t size)
 451 {
 452         const size_t entry_size = sizeof(struct ofd_access_entry_v1);
 453         struct ofd_access_log *oal;
 454         int minor;
 455         int rc;
 456
 457         BUILD_BUG_ON(sizeof(oal->oal_name) != MAX_OBD_NAME);
 458         BUILD_BUG_ON(!is_power_of_2(entry_size));
 459
 460         if (!size)
 461                 return NULL;
 462
 463         if (!is_power_of_2(size) || (size & (entry_size - 1)) ||
 464             (unsigned int)size != size)
 465                 return ERR_PTR(-EINVAL);
 466
 467         oal = kzalloc(sizeof(*oal), GFP_KERNEL);
 468         if (!oal)
 469                 return ERR_PTR(-ENOMEM);
 470
 471         strlcpy(oal->oal_name, ofd_name, sizeof(oal->oal_name));
 472         oal->oal_log_size = size;
 473         oal->oal_entry_size = entry_size;
 474         INIT_LIST_HEAD(&oal->oal_circ_buf_list);
 475         init_rwsem(&oal->oal_buf_list_sem);
 476
 477         rc = oal_log_minor_alloc(&minor);
 478         if (rc < 0)
 479                 goto out_free;
 480
 481         device_initialize(&oal->oal_device);
 482         oal->oal_device.devt = MKDEV(oal_log_major, minor);
 483         oal->oal_device.class = oal_log_class;
 484         oal->oal_device.release = &oal_device_release;
 485         dev_set_drvdata(&oal->oal_device, oal);
 486         rc = dev_set_name(&oal->oal_device,
 487                         "%s!%s", LUSTRE_ACCESS_LOG_DIR_NAME, oal->oal_name);
 488         if (rc < 0)
 489                 goto out_minor;
 490
 491         cdev_init(&oal->oal_cdev, &oal_fops);
 492         oal->oal_cdev.owner = THIS_MODULE;
 493         rc = cdev_device_add(&oal->oal_cdev, &oal->oal_device);
 494         if (rc < 0)
 495                 goto out_device_name;
 496
 497         oal_control_event_inc();
 498
 499         return oal;
 500
 501 out_device_name:
 502         kfree_const(oal->oal_device.kobj.name);
 503 out_minor:
 504         oal_log_minor_free(minor);
 505 out_free:
 506         kfree(oal);
 507
 508         return ERR_PTR(rc);
 509 }
 510
 511 void ofd_access(const struct lu_env *env,
 512                 struct ofd_device *m,
 513                 const struct lu_fid *parent_fid,
 514                 __u64 begin, __u64 end,
 515                 unsigned int size,
 516                 unsigned int segment_count,
 517                 int rw)
 518 {
 519         unsigned int flags = (rw == READ) ? OFD_ACCESS_READ : OFD_ACCESS_WRITE;
 520         struct ofd_access_log *oal = m->ofd_access_log;
 521
 522         if (oal && (flags & m->ofd_access_log_mask)) {
 523                 struct ofd_access_entry_v1 oae = {
 524                         .oae_parent_fid = *parent_fid,
 525                         .oae_begin = begin,
 526                         .oae_end = end,
 527                         .oae_time = ktime_get_real_seconds(),
 528                         .oae_size = size,
 529                         .oae_segment_count = segment_count,
 530                         .oae_flags = flags,
 531                 };
 532                 struct oal_circ_buf *ocb;
 533                 struct lu_seq_range range;
 534                 int rc;
 535
 536                 /* learn target MDT from FID's sequence */
 537                 range.lsr_flags = LU_SEQ_RANGE_ANY;
 538                 rc = fld_server_lookup(env, m->ofd_seq_site.ss_server_fld,
 539                                        fid_seq(parent_fid), &range);
 540                 if (unlikely(rc))
 541                         CERROR("%s: can't resolve "DFID": rc=%d\n",
 542                                ofd_name(m), PFID(parent_fid), rc);
 543
 544                 down_read(&oal->oal_buf_list_sem);
 545                 list_for_each_entry(ocb, &oal->oal_circ_buf_list, ocb_list) {
 546                         /* filter by MDT index if requested */
 547                         if (ocb->ocb_filter == 0xffffffff ||
 548                             range.lsr_index == ocb->ocb_filter)
 549                                 oal_write_entry(ocb, &oae, sizeof(oae));
 550                 }
 551                 up_read(&oal->oal_buf_list_sem);
 552         }
 553 }
 554
 555 /* Called on OST umount to:
 556  * - Close the write end of the oal. The wakes any tasks sleeping in
 557  *   read or poll and makes all reads return zero once the log
 558  *   becomes empty.
 559  * - Delete the associated stuct device and cdev, preventing new
 560  *   opens. Existing opens retain a reference on the oal through
 561  *   their reference on oal_device.
 562  * The oal will be freed when the last open file handle is closed. */
 563 void ofd_access_log_delete(struct ofd_access_log *oal)
 564 {
 565         struct oal_circ_buf *ocb;
 566
 567         if (!oal)
 568                 return;
 569
 570         oal->oal_is_closed = 1;
 571         down_read(&oal->oal_buf_list_sem);
 572         list_for_each_entry(ocb, &oal->oal_circ_buf_list, ocb_list) {
 573                 wake_up_all(&ocb->ocb_read_wait_queue);
 574         }
 575         up_read(&oal->oal_buf_list_sem);
 576         cdev_device_del(&oal->oal_cdev, &oal->oal_device);
 577 }
 578
 579 /* private_data for control device file. */
 580 struct oal_control_file {
 581         int ccf_event_count;
 582 };
 583
 584 /* Control file usage:
 585  * Open /dev/lustre-access-log/control.
 586  * while (1)
 587  *   Poll for readable on control FD.
 588  *   Call ioctl(FD, LUSTRE_ACCESS_LOG_IOCTL_PRESCAN) to fetch event count.
 589  *   Scan /dev/ or /sys/class/... for new devices.
 590  */
 591 static int oal_control_file_open(struct inode *inode, struct file *filp)
 592 {
 593         struct oal_control_file *ccf;
 594         int rc;
 595
 596         rc = nonseekable_open(inode, filp);
 597         if (rc)
 598                 return rc;
 599
 600         /* ccf->ccf_event_count = 0 on open */
 601         ccf = kzalloc(sizeof(*ccf), GFP_KERNEL);
 602         if (!ccf)
 603                 return -ENOMEM;
 604
 605         filp->private_data = ccf;
 606
 607         return 0;
 608 }
 609
 610 static int oal_control_file_release(struct inode *inode, struct file *filp)
 611 {
 612         kfree(filp->private_data);
 613         return 0;
 614 }
 615
 616 static unsigned int oal_control_file_poll(struct file *filp, poll_table *wait)
 617 {
 618         struct oal_control_file *ccf = filp->private_data;
 619         unsigned int mask = 0;
 620
 621         poll_wait(filp, &oal_control_wait_queue, wait);
 622
 623         if (atomic_read(&oal_control_event_count) != ccf->ccf_event_count)
 624                 mask |= POLLIN;
 625
 626         return mask;
 627 }
 628
 629 static long oal_control_file_ioctl(struct file *filp, unsigned int cmd,
 630                                 unsigned long arg)
 631 {
 632         struct oal_control_file *ccf = filp->private_data;
 633
 634         switch (cmd) {
 635         case LUSTRE_ACCESS_LOG_IOCTL_VERSION:
 636                 return LUSTRE_ACCESS_LOG_VERSION_1;
 637         case LUSTRE_ACCESS_LOG_IOCTL_MAJOR:
 638                 return oal_log_major;
 639         case LUSTRE_ACCESS_LOG_IOCTL_PRESCAN:
 640                 ccf->ccf_event_count = atomic_read(&oal_control_event_count);
 641                 return 0;
 642         default:
 643                 return -ENOTTY;
 644         }
 645 }
 646
 647 static const struct file_operations oal_control_fops = {
 648         .owner = THIS_MODULE,
 649         .open = &oal_control_file_open,
 650         .release = &oal_control_file_release,
 651         .poll = &oal_control_file_poll,
 652         .unlocked_ioctl = &oal_control_file_ioctl,
 653         .llseek = &noop_llseek,
 654 };
 655
 656 static struct miscdevice oal_control_misc = {
 657         .minor = MISC_DYNAMIC_MINOR,
 658         .name = LUSTRE_ACCESS_LOG_DIR_NAME"!control",
 659         .fops = &oal_control_fops,
 660 };
 661
 662 int ofd_access_log_module_init(void)
 663 {
 664         dev_t dev;
 665         int rc;
 666
 667         BUILD_BUG_ON(!is_power_of_2(sizeof(struct ofd_access_entry_v1)));
 668
 669         rc = misc_register(&oal_control_misc);
 670         if (rc)
 671                 return rc;
 672
 673         rc = alloc_chrdev_region(&dev, 0, OAL_DEV_COUNT,
 674                                 LUSTRE_ACCESS_LOG_DIR_NAME);
 675         if (rc)
 676                 goto out_oal_control_misc;
 677
 678         oal_log_major = MAJOR(dev);
 679
 680         oal_log_class = class_create(THIS_MODULE, LUSTRE_ACCESS_LOG_DIR_NAME);
 681         if (IS_ERR(oal_log_class)) {
 682                 rc = PTR_ERR(oal_log_class);
 683                 goto out_dev;
 684         }
 685
 686         return 0;
 687 out_dev:
 688         unregister_chrdev_region(dev, OAL_DEV_COUNT);
 689 out_oal_control_misc:
 690         misc_deregister(&oal_control_misc);
 691
 692         return rc;
 693 }
 694
 695 void ofd_access_log_module_exit(void)
 696 {
 697         class_destroy(oal_log_class);
 698         unregister_chrdev_region(MKDEV(oal_log_major, 0), OAL_DEV_COUNT);
 699         idr_destroy(&oal_log_minor_idr);
 700         misc_deregister(&oal_control_misc);
 701 }