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/idr.h>
   6 #include <linux/kernel.h>
   7 #include <linux/miscdevice.h>
   8 #include <linux/module.h>
   9 #include <linux/poll.h>
  10 #include <linux/slab.h>
  11 #include <linux/types.h>
  12 #include <linux/uaccess.h>
  13 #include <uapi/linux/lustre/lustre_idl.h>
  14 #include <uapi/linux/lustre/lustre_access_log.h>
  15 #include "ofd_internal.h"
  16
  17 /* OFD access logs: OST (OFD) RPC handlers log accesses by FID and
  18  * PFID which are read from userspace through character device files
  19  * (/dev/lustre-access-log/scratch-OST0000). Accesses are described by
  20  * struct ofd_access_entry_v1. The char device implements read()
  21  * (blocking and nonblocking) and poll(), along with an ioctl that
  22  * returns diagnostic information on an oal device.
  23  *
  24  * A control device (/dev/lustre-access-log/control) supports an ioctl()
  25  * plus poll() method to for oal discovery. See uses of
  26  * oal_control_event_count and oal_control_wait_queue for details.
  27  *
  28  * oal log size and entry size are restricted to powers of 2 to
  29  * support circ_buf methods. See Documentation/core-api/circular-buffers.rst
  30  * in the linux tree for more information.
  31  *
  32  * The associated struct device (*oal_device) owns the oal. The
  33  * release() method of oal_device frees the oal and releases its
  34  * minor. This may seem slightly more complicated than necessary but
  35  * it allows the OST to be unmounted while the oal still has open file
  36  * descriptors.
  37  */
  38
  39 enum {
  40         OAL_DEV_COUNT = 1 << MINORBITS,
  41 };
  42
  43 struct ofd_access_log {
  44         char oal_name[128]; /* lustre-OST0000 */
  45         struct device oal_device;
  46         struct cdev oal_cdev;
  47         struct rw_semaphore oal_buf_list_sem;
  48         struct list_head oal_circ_buf_list;
  49         unsigned int oal_is_closed;
  50         unsigned int oal_log_size;
  51         unsigned int oal_entry_size;
  52 };
  53
  54 struct oal_circ_buf {
  55         struct list_head ocb_list;
  56         spinlock_t ocb_write_lock;
  57         spinlock_t ocb_read_lock;
  58         struct ofd_access_log *ocb_access_log;
  59         __u32 ocb_filter;
  60         wait_queue_head_t ocb_read_wait_queue;
  61         unsigned int ocb_drop_count;
  62         struct circ_buf ocb_circ;
  63 };
  64
  65 static atomic_t oal_control_event_count = ATOMIC_INIT(0);
  66 static DECLARE_WAIT_QUEUE_HEAD(oal_control_wait_queue);
  67
  68 static struct class *oal_log_class;
  69 static unsigned int oal_log_major;
  70 static DEFINE_IDR(oal_log_minor_idr); /* TODO Use ida instead. */
  71 static DEFINE_SPINLOCK(oal_log_minor_lock);
  72
  73 bool ofd_access_log_size_is_valid(unsigned int size)
  74 {
  75         const unsigned int size_min = 2 * sizeof(struct ofd_access_entry_v1);
  76         const unsigned int size_max = 1U << 30;
  77
  78         if (size == 0)
  79                 return true;
  80
  81         return is_power_of_2(size) && size_min <= size && size <= size_max;
  82 }
  83
  84 static void oal_control_event_inc(void)
  85 {
  86         atomic_inc(&oal_control_event_count);
  87         wake_up(&oal_control_wait_queue);
  88 }
  89
  90 static int oal_log_minor_alloc(int *pminor)
  91 {
  92         void *OAL_LOG_MINOR_ALLOCED = (void *)-1;
  93         int minor;
  94
  95         idr_preload(GFP_KERNEL);
  96         spin_lock(&oal_log_minor_lock);
  97         minor = idr_alloc(&oal_log_minor_idr, OAL_LOG_MINOR_ALLOCED, 0,
  98                         OAL_DEV_COUNT, GFP_NOWAIT);
  99         spin_unlock(&oal_log_minor_lock);
 100         idr_preload_end();
 101
 102         if (minor < 0)
 103                 return minor;
 104
 105         *pminor = minor;
 106
 107         return 0;
 108 }
 109
 110 static void oal_log_minor_free(int minor)
 111 {
 112         spin_lock(&oal_log_minor_lock);
 113         idr_remove(&oal_log_minor_idr, minor);
 114         spin_unlock(&oal_log_minor_lock);
 115 }
 116
 117 static bool oal_is_empty(struct oal_circ_buf *ocb)
 118 {
 119         struct ofd_access_log *oal = ocb->ocb_access_log;
 120
 121         return CIRC_CNT(ocb->ocb_circ.head,
 122                         ocb->ocb_circ.tail,
 123                         oal->oal_log_size) < oal->oal_entry_size;
 124 }
 125
 126 static ssize_t oal_write_entry(struct oal_circ_buf *ocb,
 127                         const void *entry, size_t entry_size)
 128 {
 129         struct ofd_access_log *oal = ocb->ocb_access_log;
 130         struct circ_buf *circ = &ocb->ocb_circ;
 131         unsigned int head;
 132         unsigned int tail;
 133         ssize_t rc;
 134
 135         if (entry_size != oal->oal_entry_size)
 136                 return -EINVAL;
 137
 138         spin_lock(&ocb->ocb_write_lock);
 139         head = circ->head;
 140         tail = READ_ONCE(circ->tail);
 141
 142         /* CIRC_SPACE() return space available, 0..oal_log_size -
 143          * 1. It always leaves one free char, since a completely full
 144          * buffer would have head == tail, which is the same as empty. */
 145         if (CIRC_SPACE(head, tail, oal->oal_log_size) < oal->oal_entry_size) {
 146                 ocb->ocb_drop_count++;
 147                 rc = -EAGAIN;
 148                 goto out_write_lock;
 149         }
 150
 151         memcpy(&circ->buf[head], entry, entry_size);
 152         rc = entry_size;
 153
 154         /* Ensure the entry is stored before we update the head. */
 155         smp_store_release(&circ->head,
 156                         (head + oal->oal_entry_size) & (oal->oal_log_size - 1));
 157
 158         wake_up(&ocb->ocb_read_wait_queue);
 159 out_write_lock:
 160         spin_unlock(&ocb->ocb_write_lock);
 161
 162         return rc;
 163 }
 164
 165 /* Read one entry from the log and return its size. Non-blocking.
 166  * When the log is empty we return -EAGAIN if the OST is still mounted
 167  * and 0 otherwise.
 168  */
 169 static ssize_t oal_read_entry(struct oal_circ_buf *ocb,
 170                         void *entry_buf, size_t entry_buf_size)
 171 {
 172         struct ofd_access_log *oal = ocb->ocb_access_log;
 173         struct circ_buf *circ = &ocb->ocb_circ;
 174         unsigned int head;
 175         unsigned int tail;
 176         ssize_t rc;
 177
 178         /* XXX This method may silently truncate entries when
 179          * entry_buf_size is less than oal_entry_size. But that's OK
 180          * because you know what you are doing. */
 181         spin_lock(&ocb->ocb_read_lock);
 182
 183         /* Memory barrier usage follows circular-buffers.txt. */
 184         head = smp_load_acquire(&circ->head);
 185         tail = circ->tail;
 186
 187         if (!CIRC_CNT(head, tail, oal->oal_log_size)) {
 188                 rc = oal->oal_is_closed ? 0 : -EAGAIN;
 189                 goto out_read_lock;
 190         }
 191
 192         BUG_ON(CIRC_CNT(head, tail, oal->oal_log_size) < oal->oal_entry_size);
 193
 194         /* Extract one entry from the buffer. */
 195         rc = min_t(size_t, oal->oal_entry_size, entry_buf_size);
 196         memcpy(entry_buf, &circ->buf[tail], rc);
 197
 198         /* Memory barrier usage follows circular-buffers.txt. */
 199         smp_store_release(&circ->tail,
 200                         (tail + oal->oal_entry_size) & (oal->oal_log_size - 1));
 201
 202 out_read_lock:
 203         spin_unlock(&ocb->ocb_read_lock);
 204
 205         return rc;
 206 }
 207
 208 static int oal_file_open(struct inode *inode, struct file *filp)
 209 {
 210         struct ofd_access_log *oal;
 211         struct oal_circ_buf *ocb;
 212
 213         oal = container_of(inode->i_cdev, struct ofd_access_log, oal_cdev);
 214
 215         ocb = kzalloc(sizeof(*ocb), GFP_KERNEL);
 216         if (!ocb)
 217                 return -ENOMEM;
 218         ocb->ocb_circ.buf = vmalloc(oal->oal_log_size);
 219         if (!ocb->ocb_circ.buf) {
 220                 kfree(ocb);
 221                 return -ENOMEM;
 222         }
 223
 224         spin_lock_init(&ocb->ocb_write_lock);
 225         spin_lock_init(&ocb->ocb_read_lock);
 226         ocb->ocb_access_log = oal;
 227         init_waitqueue_head(&ocb->ocb_read_wait_queue);
 228
 229         down_write(&oal->oal_buf_list_sem);
 230         list_add(&ocb->ocb_list, &oal->oal_circ_buf_list);
 231         up_write(&oal->oal_buf_list_sem);
 232
 233         filp->private_data = ocb;
 234
 235         return nonseekable_open(inode, filp);
 236 }
 237
 238 /* User buffer size must be a multiple of ofd access entry size. */
 239 static ssize_t oal_file_read(struct file *filp, char __user *buf, size_t count,
 240                         loff_t *ppos)
 241 {
 242         struct oal_circ_buf *ocb = filp->private_data;
 243         struct ofd_access_log *oal = ocb->ocb_access_log;
 244         void *entry;
 245         size_t size = 0;
 246         int rc = 0;
 247
 248         if (!count)
 249                 return 0;
 250
 251         if (count & (oal->oal_entry_size - 1))
 252                 return -EINVAL;
 253
 254         entry = kzalloc(oal->oal_entry_size, GFP_KERNEL);
 255         if (!entry)
 256                 return -ENOMEM;
 257
 258         while (size < count) {
 259                 rc = oal_read_entry(ocb, entry, oal->oal_entry_size);
 260                 if (rc == -EAGAIN) {
 261                         if (filp->f_flags & O_NONBLOCK)
 262                                 break;
 263
 264                         rc = wait_event_interruptible(ocb->ocb_read_wait_queue,
 265                                 !oal_is_empty(ocb) || oal->oal_is_closed);
 266                         if (rc)
 267                                 break;
 268                 } else if (rc <= 0) {
 269                         break; /* cloed or error */
 270                 } else {
 271                         if (copy_to_user(buf, entry, oal->oal_entry_size)) {
 272                                 rc = -EFAULT;
 273                                 break;
 274                         }
 275
 276                         buf += oal->oal_entry_size;
 277                         size += oal->oal_entry_size;
 278                 }
 279         }
 280
 281         kfree(entry);
 282
 283         return size ? size : rc;
 284 }
 285
 286 /* Included for test purposes. User buffer size must be a multiple of
 287  * ofd access entry size. */
 288 static ssize_t oal_file_write(struct file *filp, const char __user *buf,
 289                         size_t count, loff_t *ppos)
 290 {
 291         struct oal_circ_buf *ocb = filp->private_data;
 292         struct ofd_access_log *oal = ocb->ocb_access_log;
 293         void *entry;
 294         size_t size = 0;
 295         ssize_t rc = 0;
 296
 297         if (!count)
 298                 return 0;
 299
 300         if (count & (oal->oal_entry_size - 1))
 301                 return -EINVAL;
 302
 303         entry = kzalloc(oal->oal_entry_size, GFP_KERNEL);
 304         if (!entry)
 305                 return -ENOMEM;
 306
 307         while (size < count) {
 308                 if (copy_from_user(entry, buf, oal->oal_entry_size)) {
 309                         rc = -EFAULT;
 310                         break;
 311                 }
 312
 313                 rc = oal_write_entry(ocb, entry, oal->oal_entry_size);
 314                 if (rc <= 0)
 315                         break;
 316
 317                 buf += oal->oal_entry_size;
 318                 size += oal->oal_entry_size;
 319         }
 320
 321         kfree(entry);
 322
 323         return size > 0 ? size : rc;
 324 }
 325
 326 unsigned int oal_file_poll(struct file *filp, struct poll_table_struct *wait)
 327 {
 328         struct oal_circ_buf *ocb = filp->private_data;
 329         struct ofd_access_log *oal = ocb->ocb_access_log;
 330         unsigned int mask = 0;
 331
 332         poll_wait(filp, &ocb->ocb_read_wait_queue, wait);
 333
 334         spin_lock(&ocb->ocb_read_lock);
 335
 336         if (!oal_is_empty(ocb) || oal->oal_is_closed)
 337                 mask |= POLLIN;
 338
 339         spin_unlock(&ocb->ocb_read_lock);
 340
 341         return mask;
 342 }
 343
 344 static long oal_ioctl_info(struct oal_circ_buf *ocb, void __user *uarg)
 345 {
 346         struct ofd_access_log *oal = ocb->ocb_access_log;
 347         struct lustre_access_log_info_v1 __user *lali;
 348         u32 entry_count = CIRC_CNT(ocb->ocb_circ.head,
 349                                 ocb->ocb_circ.tail,
 350                                 oal->oal_log_size) / oal->oal_entry_size;
 351         u32 entry_space = CIRC_SPACE(ocb->ocb_circ.head,
 352                                 ocb->ocb_circ.tail,
 353                                 oal->oal_log_size) / oal->oal_entry_size;
 354
 355         lali = uarg;
 356         BUILD_BUG_ON(sizeof(lali->lali_name) != sizeof(oal->oal_name));
 357
 358         if (put_user(LUSTRE_ACCESS_LOG_VERSION_1, &lali->lali_version))
 359                 return -EFAULT;
 360
 361         if (put_user(LUSTRE_ACCESS_LOG_TYPE_OFD, &lali->lali_type))
 362                 return -EFAULT;
 363
 364         if (copy_to_user(lali->lali_name, oal->oal_name, sizeof(oal->oal_name)))
 365                 return -EFAULT;
 366
 367         if (put_user(oal->oal_log_size, &lali->lali_log_size))
 368                 return -EFAULT;
 369
 370         if (put_user(oal->oal_entry_size, &lali->lali_entry_size))
 371                 return -EFAULT;
 372
 373         if (put_user(ocb->ocb_circ.head, &lali->_lali_head))
 374                 return -EFAULT;
 375
 376         if (put_user(ocb->ocb_circ.tail, &lali->_lali_tail))
 377                 return -EFAULT;
 378
 379         if (put_user(entry_space, &lali->_lali_entry_space))
 380                 return -EFAULT;
 381
 382         if (put_user(entry_count, &lali->_lali_entry_count))
 383                 return -EFAULT;
 384
 385         if (put_user(ocb->ocb_drop_count, &lali->_lali_drop_count))
 386                 return -EFAULT;
 387
 388         if (put_user(oal->oal_is_closed, &lali->_lali_is_closed))
 389                 return -EFAULT;
 390
 391         return 0;
 392 }
 393
 394 static long oal_file_ioctl(struct file *filp, unsigned int cmd,
 395                            unsigned long arg)
 396 {
 397         struct oal_circ_buf *ocb = filp->private_data;
 398
 399         switch (cmd) {
 400         case LUSTRE_ACCESS_LOG_IOCTL_VERSION:
 401                 return LUSTRE_ACCESS_LOG_VERSION_1;
 402         case LUSTRE_ACCESS_LOG_IOCTL_INFO:
 403                 return oal_ioctl_info(ocb, (void __user *)arg);
 404         case LUSTRE_ACCESS_LOG_IOCTL_FILTER:
 405                 ocb->ocb_filter = arg;
 406                 return 0;
 407         default:
 408                 return -ENOTTY;
 409         }
 410 }
 411
 412 static int oal_file_release(struct inode *inode, struct file *filp)
 413 {
 414         struct oal_circ_buf *ocb = filp->private_data;
 415         struct ofd_access_log *oal = ocb->ocb_access_log;
 416
 417         down_write(&oal->oal_buf_list_sem);
 418         list_del(&ocb->ocb_list);
 419         up_write(&oal->oal_buf_list_sem);
 420
 421         vfree(ocb->ocb_circ.buf);
 422         kfree(ocb);
 423
 424         return 0;
 425 }
 426
 427 static const struct file_operations oal_fops = {
 428         .owner = THIS_MODULE,
 429         .open = &oal_file_open,
 430         .release = &oal_file_release,
 431         .unlocked_ioctl = &oal_file_ioctl,
 432         .read = &oal_file_read,
 433         .write = &oal_file_write,
 434         .poll = &oal_file_poll,
 435 #ifdef HAVE_NO_LLSEEK
 436         .llseek = &no_llseek,
 437 #endif
 438 };
 439
 440 static void oal_device_release(struct device *dev)
 441 {
 442         struct ofd_access_log *oal = dev_get_drvdata(dev);
 443
 444         oal_log_minor_free(MINOR(oal->oal_device.devt));
 445         BUG_ON(!list_empty(&oal->oal_circ_buf_list));
 446         kfree(oal);
 447 }
 448
 449 struct ofd_access_log *ofd_access_log_create(const char *ofd_name, size_t size)
 450 {
 451         const size_t entry_size = sizeof(struct ofd_access_entry_v1);
 452         struct ofd_access_log *oal;
 453         int minor;
 454         int rc;
 455
 456         BUILD_BUG_ON(sizeof(oal->oal_name) != MAX_OBD_NAME);
 457         BUILD_BUG_ON(!is_power_of_2(entry_size));
 458
 459         if (!size)
 460                 return NULL;
 461
 462         if (!is_power_of_2(size) || (size & (entry_size - 1)) ||
 463             (unsigned int)size != size)
 464                 return ERR_PTR(-EINVAL);
 465
 466         oal = kzalloc(sizeof(*oal), GFP_KERNEL);
 467         if (!oal)
 468                 return ERR_PTR(-ENOMEM);
 469
 470         strlcpy(oal->oal_name, ofd_name, sizeof(oal->oal_name));
 471         oal->oal_log_size = size;
 472         oal->oal_entry_size = entry_size;
 473         INIT_LIST_HEAD(&oal->oal_circ_buf_list);
 474         init_rwsem(&oal->oal_buf_list_sem);
 475
 476         rc = oal_log_minor_alloc(&minor);
 477         if (rc < 0)
 478                 goto out_free;
 479
 480         device_initialize(&oal->oal_device);
 481         oal->oal_device.devt = MKDEV(oal_log_major, minor);
 482         oal->oal_device.class = oal_log_class;
 483         oal->oal_device.release = &oal_device_release;
 484         dev_set_drvdata(&oal->oal_device, oal);
 485         rc = dev_set_name(&oal->oal_device,
 486                         "%s!%s", LUSTRE_ACCESS_LOG_DIR_NAME, oal->oal_name);
 487         if (rc < 0)
 488                 goto out_minor;
 489
 490         cdev_init(&oal->oal_cdev, &oal_fops);
 491         oal->oal_cdev.owner = THIS_MODULE;
 492         rc = cdev_device_add(&oal->oal_cdev, &oal->oal_device);
 493         if (rc < 0)
 494                 goto out_device_name;
 495
 496         oal_control_event_inc();
 497
 498         return oal;
 499
 500 out_device_name:
 501         kfree_const(oal->oal_device.kobj.name);
 502 out_minor:
 503         oal_log_minor_free(minor);
 504 out_free:
 505         kfree(oal);
 506
 507         return ERR_PTR(rc);
 508 }
 509
 510 void ofd_access(const struct lu_env *env,
 511                 struct ofd_device *m,
 512                 const struct lu_fid *parent_fid,
 513                 __u64 begin, __u64 end,
 514                 unsigned int size,
 515                 unsigned int segment_count,
 516                 int rw)
 517 {
 518         unsigned int flags = (rw == READ) ? OFD_ACCESS_READ : OFD_ACCESS_WRITE;
 519         struct ofd_access_log *oal = m->ofd_access_log;
 520
 521         /* obdfilter-survey does not set parent FIDs. */
 522         if (fid_is_zero(parent_fid))
 523                 return;
 524
 525         if (oal && (flags & m->ofd_access_log_mask)) {
 526                 struct ofd_access_entry_v1 oae = {
 527                         .oae_parent_fid = *parent_fid,
 528                         .oae_begin = begin,
 529                         .oae_end = end,
 530                         .oae_time = ktime_get_real_seconds(),
 531                         .oae_size = size,
 532                         .oae_segment_count = segment_count,
 533                         .oae_flags = flags,
 534                 };
 535                 struct lu_seq_range range = {
 536                         .lsr_flags = LU_SEQ_RANGE_ANY,
 537                 };
 538                 struct oal_circ_buf *ocb;
 539                 int rc;
 540
 541                 /* learn target MDT from FID's sequence */
 542                 rc = fld_server_lookup(env, m->ofd_seq_site.ss_server_fld,
 543                                        fid_seq(parent_fid), &range);
 544                 if (unlikely(rc))
 545                         CERROR("%s: can't resolve "DFID": rc=%d\n",
 546                                ofd_name(m), PFID(parent_fid), rc);
 547
 548                 down_read(&oal->oal_buf_list_sem);
 549                 list_for_each_entry(ocb, &oal->oal_circ_buf_list, ocb_list) {
 550                         /* filter by MDT index if requested */
 551                         if (ocb->ocb_filter == 0xffffffff ||
 552                             range.lsr_index == ocb->ocb_filter)
 553                                 oal_write_entry(ocb, &oae, sizeof(oae));
 554                 }
 555                 up_read(&oal->oal_buf_list_sem);
 556         }
 557 }
 558
 559 /* Called on OST umount to:
 560  * - Close the write end of the oal. The wakes any tasks sleeping in
 561  *   read or poll and makes all reads return zero once the log
 562  *   becomes empty.
 563  * - Delete the associated stuct device and cdev, preventing new
 564  *   opens. Existing opens retain a reference on the oal through
 565  *   their reference on oal_device.
 566  * The oal will be freed when the last open file handle is closed. */
 567 void ofd_access_log_delete(struct ofd_access_log *oal)
 568 {
 569         struct oal_circ_buf *ocb;
 570
 571         if (!oal)
 572                 return;
 573
 574         oal->oal_is_closed = 1;
 575         down_read(&oal->oal_buf_list_sem);
 576         list_for_each_entry(ocb, &oal->oal_circ_buf_list, ocb_list)
 577                 wake_up(&ocb->ocb_read_wait_queue);
 578         up_read(&oal->oal_buf_list_sem);
 579         cdev_device_del(&oal->oal_cdev, &oal->oal_device);
 580 }
 581
 582 /* private_data for control device file. */
 583 struct oal_control_file {
 584         int ccf_event_count;
 585 };
 586
 587 /* Control file usage:
 588  * Open /dev/lustre-access-log/control.
 589  * while (1)
 590  *   Poll for readable on control FD.
 591  *   Call ioctl(FD, LUSTRE_ACCESS_LOG_IOCTL_PRESCAN) to fetch event count.
 592  *   Scan /dev/ or /sys/class/... for new devices.
 593  */
 594 static int oal_control_file_open(struct inode *inode, struct file *filp)
 595 {
 596         struct oal_control_file *ccf;
 597         int rc;
 598
 599         rc = nonseekable_open(inode, filp);
 600         if (rc)
 601                 return rc;
 602
 603         /* ccf->ccf_event_count = 0 on open */
 604         ccf = kzalloc(sizeof(*ccf), GFP_KERNEL);
 605         if (!ccf)
 606                 return -ENOMEM;
 607
 608         filp->private_data = ccf;
 609
 610         return 0;
 611 }
 612
 613 static int oal_control_file_release(struct inode *inode, struct file *filp)
 614 {
 615         kfree(filp->private_data);
 616         return 0;
 617 }
 618
 619 static unsigned int oal_control_file_poll(struct file *filp, poll_table *wait)
 620 {
 621         struct oal_control_file *ccf = filp->private_data;
 622         unsigned int mask = 0;
 623
 624         poll_wait(filp, &oal_control_wait_queue, wait);
 625
 626         if (atomic_read(&oal_control_event_count) != ccf->ccf_event_count)
 627                 mask |= POLLIN;
 628
 629         return mask;
 630 }
 631
 632 static long oal_control_file_ioctl(struct file *filp, unsigned int cmd,
 633                                    unsigned long arg)
 634 {
 635         struct oal_control_file *ccf = filp->private_data;
 636
 637         switch (cmd) {
 638         case LUSTRE_ACCESS_LOG_IOCTL_VERSION:
 639                 return LUSTRE_ACCESS_LOG_VERSION_1;
 640         case LUSTRE_ACCESS_LOG_IOCTL_MAJOR:
 641                 return oal_log_major;
 642         case LUSTRE_ACCESS_LOG_IOCTL_PRESCAN:
 643                 ccf->ccf_event_count = atomic_read(&oal_control_event_count);
 644                 return 0;
 645         default:
 646                 return -ENOTTY;
 647         }
 648 }
 649
 650 static const struct file_operations oal_control_fops = {
 651         .owner = THIS_MODULE,
 652         .open = &oal_control_file_open,
 653         .release = &oal_control_file_release,
 654         .poll = &oal_control_file_poll,
 655         .unlocked_ioctl = &oal_control_file_ioctl,
 656         .llseek = &noop_llseek,
 657 };
 658
 659 static struct miscdevice oal_control_misc = {
 660         .minor = MISC_DYNAMIC_MINOR,
 661         .name = LUSTRE_ACCESS_LOG_DIR_NAME"!control",
 662         .fops = &oal_control_fops,
 663 };
 664
 665 int ofd_access_log_module_init(void)
 666 {
 667         dev_t dev;
 668         int rc;
 669
 670         BUILD_BUG_ON(!is_power_of_2(sizeof(struct ofd_access_entry_v1)));
 671
 672         rc = misc_register(&oal_control_misc);
 673         if (rc)
 674                 return rc;
 675
 676         rc = alloc_chrdev_region(&dev, 0, OAL_DEV_COUNT,
 677                                 LUSTRE_ACCESS_LOG_DIR_NAME);
 678         if (rc)
 679                 goto out_oal_control_misc;
 680
 681         oal_log_major = MAJOR(dev);
 682
 683         oal_log_class = class_create(THIS_MODULE, LUSTRE_ACCESS_LOG_DIR_NAME);
 684         if (IS_ERR(oal_log_class)) {
 685                 rc = PTR_ERR(oal_log_class);
 686                 goto out_dev;
 687         }
 688
 689         return 0;
 690 out_dev:
 691         unregister_chrdev_region(dev, OAL_DEV_COUNT);
 692 out_oal_control_misc:
 693         misc_deregister(&oal_control_misc);
 694
 695         return rc;
 696 }
 697
 698 void ofd_access_log_module_exit(void)
 699 {
 700         class_destroy(oal_log_class);
 701         unregister_chrdev_region(MKDEV(oal_log_major, 0), OAL_DEV_COUNT);
 702         idr_destroy(&oal_log_minor_idr);
 703         misc_deregister(&oal_control_misc);
 704 }