drivers/staging/ramzswap/ramzswap_drv.c

   1 /*
   2  * Compressed RAM based swap device
   3  *
   4  * Copyright (C) 2008, 2009, 2010  Nitin Gupta
   5  *
   6  * This code is released using a dual license strategy: BSD/GPL
   7  * You can choose the licence that better fits your requirements.
   8  *
   9  * Released under the terms of 3-clause BSD License
  10  * Released under the terms of GNU General Public License Version 2.0
  11  *
  12  * Project home: http://compcache.googlecode.com
  13  */
  14
  15 #define KMSG_COMPONENT "ramzswap"
  16 #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
  17
  18 #include <linux/module.h>
  19 #include <linux/kernel.h>
  20 #include <linux/bitops.h>
  21 #include <linux/blkdev.h>
  22 #include <linux/buffer_head.h>
  23 #include <linux/device.h>
  24 #include <linux/genhd.h>
  25 #include <linux/highmem.h>
  26 #include <linux/slab.h>
  27 #include <linux/lzo.h>
  28 #include <linux/string.h>
  29 #include <linux/swap.h>
  30 #include <linux/swapops.h>
  31 #include <linux/vmalloc.h>
  32
  33 #include "ramzswap_drv.h"
  34
  35 /* Globals */
  36 static int ramzswap_major;
  37 static struct ramzswap *devices;
  38
  39 /* Module params (documentation at end) */
  40 static unsigned int num_devices;
  41
  42 static int rzs_test_flag(struct ramzswap *rzs, u32 index,
  43                         enum rzs_pageflags flag)
  44 {
  45         return rzs->table[index].flags & BIT(flag);
  46 }
  47
  48 static void rzs_set_flag(struct ramzswap *rzs, u32 index,
  49                         enum rzs_pageflags flag)
  50 {
  51         rzs->table[index].flags |= BIT(flag);
  52 }
  53
  54 static void rzs_clear_flag(struct ramzswap *rzs, u32 index,
  55                         enum rzs_pageflags flag)
  56 {
  57         rzs->table[index].flags &= ~BIT(flag);
  58 }
  59
  60 static int page_zero_filled(void *ptr)
  61 {
  62         unsigned int pos;
  63         unsigned long *page;
  64
  65         page = (unsigned long *)ptr;
  66
  67         for (pos = 0; pos != PAGE_SIZE / sizeof(*page); pos++) {
  68                 if (page[pos])
  69                         return 0;
  70         }
  71
  72         return 1;
  73 }
  74
  75 static void ramzswap_set_disksize(struct ramzswap *rzs, size_t totalram_bytes)
  76 {
  77         if (!rzs->disksize) {
  78                 pr_info(
  79                 "disk size not provided. You can use disksize_kb module "
  80                 "param to specify size.\nUsing default: (%u%% of RAM).\n",
  81                 default_disksize_perc_ram
  82                 );
  83                 rzs->disksize = default_disksize_perc_ram *
  84                                         (totalram_bytes / 100);
  85         }
  86
  87         if (rzs->disksize > 2 * (totalram_bytes)) {
  88                 pr_info(
  89                 "There is little point creating a ramzswap of greater than "
  90                 "twice the size of memory since we expect a 2:1 compression "
  91                 "ratio. Note that ramzswap uses about 0.1%% of the size of "
  92                 "the swap device when not in use so a huge ramzswap is "
  93                 "wasteful.\n"
  94                 "\tMemory Size: %zu kB\n"
  95                 "\tSize you selected: %zu kB\n"
  96                 "Continuing anyway ...\n",
  97                 totalram_bytes >> 10, rzs->disksize
  98                 );
  99         }
 100
 101         rzs->disksize &= PAGE_MASK;
 102 }
 103
 104 static void ramzswap_ioctl_get_stats(struct ramzswap *rzs,
 105                         struct ramzswap_ioctl_stats *s)
 106 {
 107         s->disksize = rzs->disksize;
 108
 109 #if defined(CONFIG_RAMZSWAP_STATS)
 110         {
 111         struct ramzswap_stats *rs = &rzs->stats;
 112         size_t succ_writes, mem_used;
 113         unsigned int good_compress_perc = 0, no_compress_perc = 0;
 114
 115         mem_used = xv_get_total_size_bytes(rzs->mem_pool)
 116                         + (rs->pages_expand << PAGE_SHIFT);
 117         succ_writes = rzs_stat64_read(rzs, &rs->num_writes) -
 118                         rzs_stat64_read(rzs, &rs->failed_writes);
 119
 120         if (succ_writes && rs->pages_stored) {
 121                 good_compress_perc = rs->good_compress * 100
 122                                         / rs->pages_stored;
 123                 no_compress_perc = rs->pages_expand * 100
 124                                         / rs->pages_stored;
 125         }
 126
 127         s->num_reads = rzs_stat64_read(rzs, &rs->num_reads);
 128         s->num_writes = rzs_stat64_read(rzs, &rs->num_writes);
 129         s->failed_reads = rzs_stat64_read(rzs, &rs->failed_reads);
 130         s->failed_writes = rzs_stat64_read(rzs, &rs->failed_writes);
 131         s->invalid_io = rzs_stat64_read(rzs, &rs->invalid_io);
 132         s->notify_free = rzs_stat64_read(rzs, &rs->notify_free);
 133         s->pages_zero = rs->pages_zero;
 134
 135         s->good_compress_pct = good_compress_perc;
 136         s->pages_expand_pct = no_compress_perc;
 137
 138         s->pages_stored = rs->pages_stored;
 139         s->pages_used = mem_used >> PAGE_SHIFT;
 140         s->orig_data_size = rs->pages_stored << PAGE_SHIFT;
 141         s->compr_data_size = rs->compr_size;
 142         s->mem_used_total = mem_used;
 143         }
 144 #endif /* CONFIG_RAMZSWAP_STATS */
 145 }
 146
 147 static void ramzswap_free_page(struct ramzswap *rzs, size_t index)
 148 {
 149         u32 clen;
 150         void *obj;
 151
 152         struct page *page = rzs->table[index].page;
 153         u32 offset = rzs->table[index].offset;
 154
 155         if (unlikely(!page)) {
 156                 /*
 157                  * No memory is allocated for zero filled pages.
 158                  * Simply clear zero page flag.
 159                  */
 160                 if (rzs_test_flag(rzs, index, RZS_ZERO)) {
 161                         rzs_clear_flag(rzs, index, RZS_ZERO);
 162                         rzs_stat_dec(&rzs->stats.pages_zero);
 163                 }
 164                 return;
 165         }
 166
 167         if (unlikely(rzs_test_flag(rzs, index, RZS_UNCOMPRESSED))) {
 168                 clen = PAGE_SIZE;
 169                 __free_page(page);
 170                 rzs_clear_flag(rzs, index, RZS_UNCOMPRESSED);
 171                 rzs_stat_dec(&rzs->stats.pages_expand);
 172                 goto out;
 173         }
 174
 175         obj = kmap_atomic(page, KM_USER0) + offset;
 176         clen = xv_get_object_size(obj) - sizeof(struct zobj_header);
 177         kunmap_atomic(obj, KM_USER0);
 178
 179         xv_free(rzs->mem_pool, page, offset);
 180         if (clen <= PAGE_SIZE / 2)
 181                 rzs_stat_dec(&rzs->stats.good_compress);
 182
 183 out:
 184         rzs->stats.compr_size -= clen;
 185         rzs_stat_dec(&rzs->stats.pages_stored);
 186
 187         rzs->table[index].page = NULL;
 188         rzs->table[index].offset = 0;
 189 }
 190
 191 static void handle_zero_page(struct page *page)
 192 {
 193         void *user_mem;
 194
 195         user_mem = kmap_atomic(page, KM_USER0);
 196         memset(user_mem, 0, PAGE_SIZE);
 197         kunmap_atomic(user_mem, KM_USER0);
 198
 199         flush_dcache_page(page);
 200 }
 201
 202 static void handle_uncompressed_page(struct ramzswap *rzs,
 203                                 struct page *page, u32 index)
 204 {
 205         unsigned char *user_mem, *cmem;
 206
 207         user_mem = kmap_atomic(page, KM_USER0);
 208         cmem = kmap_atomic(rzs->table[index].page, KM_USER1) +
 209                         rzs->table[index].offset;
 210
 211         memcpy(user_mem, cmem, PAGE_SIZE);
 212         kunmap_atomic(user_mem, KM_USER0);
 213         kunmap_atomic(cmem, KM_USER1);
 214
 215         flush_dcache_page(page);
 216 }
 217
 218 static int ramzswap_read(struct ramzswap *rzs, struct bio *bio)
 219 {
 220
 221         int i;
 222         u32 index;
 223         struct bio_vec *bvec;
 224
 225         rzs_stat64_inc(rzs, &rzs->stats.num_reads);
 226
 227         index = bio->bi_sector >> SECTORS_PER_PAGE_SHIFT;
 228         bio_for_each_segment(bvec, bio, i) {
 229                 int ret;
 230                 size_t clen;
 231                 struct page *page;
 232                 struct zobj_header *zheader;
 233                 unsigned char *user_mem, *cmem;
 234
 235                 page = bvec->bv_page;
 236
 237                 if (rzs_test_flag(rzs, index, RZS_ZERO)) {
 238                         handle_zero_page(page);
 239                         continue;
 240                 }
 241
 242                 /* Requested page is not present in compressed area */
 243                 if (unlikely(!rzs->table[index].page)) {
 244                         pr_debug("Read before write: sector=%lu, size=%u",
 245                                 (ulong)(bio->bi_sector), bio->bi_size);
 246                         /* Do nothing */
 247                         continue;
 248                 }
 249
 250                 /* Page is stored uncompressed since it's incompressible */
 251                 if (unlikely(rzs_test_flag(rzs, index, RZS_UNCOMPRESSED))) {
 252                         handle_uncompressed_page(rzs, page, index);
 253                         continue;
 254                 }
 255
 256                 user_mem = kmap_atomic(page, KM_USER0);
 257                 clen = PAGE_SIZE;
 258
 259                 cmem = kmap_atomic(rzs->table[index].page, KM_USER1) +
 260                                 rzs->table[index].offset;
 261
 262                 ret = lzo1x_decompress_safe(
 263                         cmem + sizeof(*zheader),
 264                         xv_get_object_size(cmem) - sizeof(*zheader),
 265                         user_mem, &clen);
 266
 267                 kunmap_atomic(user_mem, KM_USER0);
 268                 kunmap_atomic(cmem, KM_USER1);
 269
 270                 /* Should NEVER happen. Return bio error if it does. */
 271                 if (unlikely(ret != LZO_E_OK)) {
 272                         pr_err("Decompression failed! err=%d, page=%u\n",
 273                                 ret, index);
 274                         rzs_stat64_inc(rzs, &rzs->stats.failed_reads);
 275                         goto out;
 276                 }
 277
 278                 flush_dcache_page(page);
 279                 index++;
 280         }
 281
 282         set_bit(BIO_UPTODATE, &bio->bi_flags);
 283         bio_endio(bio, 0);
 284         return 0;
 285
 286 out:
 287         bio_io_error(bio);
 288         return 0;
 289 }
 290
 291 static int ramzswap_write(struct ramzswap *rzs, struct bio *bio)
 292 {
 293         int i;
 294         u32 index;
 295         struct bio_vec *bvec;
 296
 297         rzs_stat64_inc(rzs, &rzs->stats.num_writes);
 298
 299         index = bio->bi_sector >> SECTORS_PER_PAGE_SHIFT;
 300
 301         bio_for_each_segment(bvec, bio, i) {
 302                 int ret;
 303                 u32 offset;
 304                 size_t clen;
 305                 struct zobj_header *zheader;
 306                 struct page *page, *page_store;
 307                 unsigned char *user_mem, *cmem, *src;
 308
 309                 page = bvec->bv_page;
 310                 src = rzs->compress_buffer;
 311
 312                 /*
 313                  * System overwrites unused sectors. Free memory associated
 314                  * with this sector now.
 315                  */
 316                 if (rzs->table[index].page ||
 317                                 rzs_test_flag(rzs, index, RZS_ZERO))
 318                         ramzswap_free_page(rzs, index);
 319
 320                 mutex_lock(&rzs->lock);
 321
 322                 user_mem = kmap_atomic(page, KM_USER0);
 323                 if (page_zero_filled(user_mem)) {
 324                         kunmap_atomic(user_mem, KM_USER0);
 325                         mutex_unlock(&rzs->lock);
 326                         rzs_stat_inc(&rzs->stats.pages_zero);
 327                         rzs_set_flag(rzs, index, RZS_ZERO);
 328                         continue;
 329                 }
 330
 331                 ret = lzo1x_1_compress(user_mem, PAGE_SIZE, src, &clen,
 332                                         rzs->compress_workmem);
 333
 334                 kunmap_atomic(user_mem, KM_USER0);
 335
 336                 if (unlikely(ret != LZO_E_OK)) {
 337                         mutex_unlock(&rzs->lock);
 338                         pr_err("Compression failed! err=%d\n", ret);
 339                         rzs_stat64_inc(rzs, &rzs->stats.failed_writes);
 340                         goto out;
 341                 }
 342
 343                 /*
 344                  * Page is incompressible. Store it as-is (uncompressed)
 345                  * since we do not want to return too many swap write
 346                  * errors which has side effect of hanging the system.
 347                  */
 348                 if (unlikely(clen > max_zpage_size)) {
 349                         clen = PAGE_SIZE;
 350                         page_store = alloc_page(GFP_NOIO | __GFP_HIGHMEM);
 351                         if (unlikely(!page_store)) {
 352                                 mutex_unlock(&rzs->lock);
 353                                 pr_info("Error allocating memory for "
 354                                         "incompressible page: %u\n", index);
 355                                 rzs_stat64_inc(rzs, &rzs->stats.failed_writes);
 356                                 goto out;
 357                         }
 358
 359                         offset = 0;
 360                         rzs_set_flag(rzs, index, RZS_UNCOMPRESSED);
 361                         rzs_stat_inc(&rzs->stats.pages_expand);
 362                         rzs->table[index].page = page_store;
 363                         src = kmap_atomic(page, KM_USER0);
 364                         goto memstore;
 365                 }
 366
 367                 if (xv_malloc(rzs->mem_pool, clen + sizeof(*zheader),
 368                                 &rzs->table[index].page, &offset,
 369                                 GFP_NOIO | __GFP_HIGHMEM)) {
 370                         mutex_unlock(&rzs->lock);
 371                         pr_info("Error allocating memory for compressed "
 372                                 "page: %u, size=%zu\n", index, clen);
 373                         rzs_stat64_inc(rzs, &rzs->stats.failed_writes);
 374                         goto out;
 375                 }
 376
 377 memstore:
 378                 rzs->table[index].offset = offset;
 379
 380                 cmem = kmap_atomic(rzs->table[index].page, KM_USER1) +
 381                                 rzs->table[index].offset;
 382
 383 #if 0
 384                 /* Back-reference needed for memory defragmentation */
 385                 if (!rzs_test_flag(rzs, index, RZS_UNCOMPRESSED)) {
 386                         zheader = (struct zobj_header *)cmem;
 387                         zheader->table_idx = index;
 388                         cmem += sizeof(*zheader);
 389                 }
 390 #endif
 391
 392                 memcpy(cmem, src, clen);
 393
 394                 kunmap_atomic(cmem, KM_USER1);
 395                 if (unlikely(rzs_test_flag(rzs, index, RZS_UNCOMPRESSED)))
 396                         kunmap_atomic(src, KM_USER0);
 397
 398                 /* Update stats */
 399                 rzs->stats.compr_size += clen;
 400                 rzs_stat_inc(&rzs->stats.pages_stored);
 401                 if (clen <= PAGE_SIZE / 2)
 402                         rzs_stat_inc(&rzs->stats.good_compress);
 403
 404                 mutex_unlock(&rzs->lock);
 405                 index++;
 406         }
 407
 408         set_bit(BIO_UPTODATE, &bio->bi_flags);
 409         bio_endio(bio, 0);
 410         return 0;
 411
 412 out:
 413         bio_io_error(bio);
 414         return 0;
 415 }
 416
 417 /*
 418  * Check if request is within bounds and page aligned.
 419  */
 420 static inline int valid_io_request(struct ramzswap *rzs, struct bio *bio)
 421 {
 422         if (unlikely(
 423                 (bio->bi_sector >= (rzs->disksize >> SECTOR_SHIFT)) ||
 424                 (bio->bi_sector & (SECTORS_PER_PAGE - 1)) ||
 425                 (bio->bi_size & (PAGE_SIZE - 1)))) {
 426
 427                 return 0;
 428         }
 429
 430         /* I/O request is valid */
 431         return 1;
 432 }
 433
 434 /*
 435  * Handler function for all ramzswap I/O requests.
 436  */
 437 static int ramzswap_make_request(struct request_queue *queue, struct bio *bio)
 438 {
 439         int ret = 0;
 440         struct ramzswap *rzs = queue->queuedata;
 441
 442         if (unlikely(!rzs->init_done)) {
 443                 bio_io_error(bio);
 444                 return 0;
 445         }
 446
 447         if (!valid_io_request(rzs, bio)) {
 448                 rzs_stat64_inc(rzs, &rzs->stats.invalid_io);
 449                 bio_io_error(bio);
 450                 return 0;
 451         }
 452
 453         switch (bio_data_dir(bio)) {
 454         case READ:
 455                 ret = ramzswap_read(rzs, bio);
 456                 break;
 457
 458         case WRITE:
 459                 ret = ramzswap_write(rzs, bio);
 460                 break;
 461         }
 462
 463         return ret;
 464 }
 465
 466 static void reset_device(struct ramzswap *rzs)
 467 {
 468         size_t index;
 469
 470         /* Do not accept any new I/O request */
 471         rzs->init_done = 0;
 472
 473         /* Free various per-device buffers */
 474         kfree(rzs->compress_workmem);
 475         free_pages((unsigned long)rzs->compress_buffer, 1);
 476
 477         rzs->compress_workmem = NULL;
 478         rzs->compress_buffer = NULL;
 479
 480         /* Free all pages that are still in this ramzswap device */
 481         for (index = 0; index < rzs->disksize >> PAGE_SHIFT; index++) {
 482                 struct page *page;
 483                 u16 offset;
 484
 485                 page = rzs->table[index].page;
 486                 offset = rzs->table[index].offset;
 487
 488                 if (!page)
 489                         continue;
 490
 491                 if (unlikely(rzs_test_flag(rzs, index, RZS_UNCOMPRESSED)))
 492                         __free_page(page);
 493                 else
 494                         xv_free(rzs->mem_pool, page, offset);
 495         }
 496
 497         vfree(rzs->table);
 498         rzs->table = NULL;
 499
 500         xv_destroy_pool(rzs->mem_pool);
 501         rzs->mem_pool = NULL;
 502
 503         /* Reset stats */
 504         memset(&rzs->stats, 0, sizeof(rzs->stats));
 505
 506         rzs->disksize = 0;
 507 }
 508
 509 static int ramzswap_ioctl_init_device(struct ramzswap *rzs)
 510 {
 511         int ret;
 512         size_t num_pages;
 513
 514         if (rzs->init_done) {
 515                 pr_info("Device already initialized!\n");
 516                 return -EBUSY;
 517         }
 518
 519         ramzswap_set_disksize(rzs, totalram_pages << PAGE_SHIFT);
 520
 521         rzs->compress_workmem = kzalloc(LZO1X_MEM_COMPRESS, GFP_KERNEL);
 522         if (!rzs->compress_workmem) {
 523                 pr_err("Error allocating compressor working memory!\n");
 524                 ret = -ENOMEM;
 525                 goto fail;
 526         }
 527
 528         rzs->compress_buffer = (void *)__get_free_pages(__GFP_ZERO, 1);
 529         if (!rzs->compress_buffer) {
 530                 pr_err("Error allocating compressor buffer space\n");
 531                 ret = -ENOMEM;
 532                 goto fail;
 533         }
 534
 535         num_pages = rzs->disksize >> PAGE_SHIFT;
 536         rzs->table = vmalloc(num_pages * sizeof(*rzs->table));
 537         if (!rzs->table) {
 538                 pr_err("Error allocating ramzswap address table\n");
 539                 /* To prevent accessing table entries during cleanup */
 540                 rzs->disksize = 0;
 541                 ret = -ENOMEM;
 542                 goto fail;
 543         }
 544         memset(rzs->table, 0, num_pages * sizeof(*rzs->table));
 545
 546         set_capacity(rzs->disk, rzs->disksize >> SECTOR_SHIFT);
 547
 548         /* ramzswap devices sort of resembles non-rotational disks */
 549         queue_flag_set_unlocked(QUEUE_FLAG_NONROT, rzs->disk->queue);
 550
 551         rzs->mem_pool = xv_create_pool();
 552         if (!rzs->mem_pool) {
 553                 pr_err("Error creating memory pool\n");
 554                 ret = -ENOMEM;
 555                 goto fail;
 556         }
 557
 558         rzs->init_done = 1;
 559
 560         pr_debug("Initialization done!\n");
 561         return 0;
 562
 563 fail:
 564         reset_device(rzs);
 565
 566         pr_err("Initialization failed: err=%d\n", ret);
 567         return ret;
 568 }
 569
 570 static int ramzswap_ioctl_reset_device(struct ramzswap *rzs)
 571 {
 572         if (rzs->init_done)
 573                 reset_device(rzs);
 574
 575         return 0;
 576 }
 577
 578 static int ramzswap_ioctl(struct block_device *bdev, fmode_t mode,
 579                         unsigned int cmd, unsigned long arg)
 580 {
 581         int ret = 0;
 582         size_t disksize_kb;
 583
 584         struct ramzswap *rzs = bdev->bd_disk->private_data;
 585
 586         switch (cmd) {
 587         case RZSIO_SET_DISKSIZE_KB:
 588                 if (rzs->init_done) {
 589                         ret = -EBUSY;
 590                         goto out;
 591                 }
 592                 if (copy_from_user(&disksize_kb, (void *)arg,
 593                                                 _IOC_SIZE(cmd))) {
 594                         ret = -EFAULT;
 595                         goto out;
 596                 }
 597                 rzs->disksize = disksize_kb << 10;
 598                 pr_info("Disk size set to %zu kB\n", disksize_kb);
 599                 break;
 600
 601         case RZSIO_GET_STATS:
 602         {
 603                 struct ramzswap_ioctl_stats *stats;
 604                 if (!rzs->init_done) {
 605                         ret = -ENOTTY;
 606                         goto out;
 607                 }
 608                 stats = kzalloc(sizeof(*stats), GFP_KERNEL);
 609                 if (!stats) {
 610                         ret = -ENOMEM;
 611                         goto out;
 612                 }
 613                 ramzswap_ioctl_get_stats(rzs, stats);
 614                 if (copy_to_user((void *)arg, stats, sizeof(*stats))) {
 615                         kfree(stats);
 616                         ret = -EFAULT;
 617                         goto out;
 618                 }
 619                 kfree(stats);
 620                 break;
 621         }
 622         case RZSIO_INIT:
 623                 ret = ramzswap_ioctl_init_device(rzs);
 624                 break;
 625
 626         case RZSIO_RESET:
 627                 /* Do not reset an active device! */
 628                 if (bdev->bd_holders) {
 629                         ret = -EBUSY;
 630                         goto out;
 631                 }
 632
 633                 /* Make sure all pending I/O is finished */
 634                 if (bdev)
 635                         fsync_bdev(bdev);
 636
 637                 ret = ramzswap_ioctl_reset_device(rzs);
 638                 break;
 639
 640         default:
 641                 pr_info("Invalid ioctl %u\n", cmd);
 642                 ret = -ENOTTY;
 643         }
 644
 645 out:
 646         return ret;
 647 }
 648
 649 void ramzswap_slot_free_notify(struct block_device *bdev, unsigned long index)
 650 {
 651         struct ramzswap *rzs;
 652
 653         rzs = bdev->bd_disk->private_data;
 654         ramzswap_free_page(rzs, index);
 655         rzs_stat64_inc(rzs, &rzs->stats.notify_free);
 656 }
 657
 658 static const struct block_device_operations ramzswap_devops = {
 659         .ioctl = ramzswap_ioctl,
 660         .swap_slot_free_notify = ramzswap_slot_free_notify,
 661         .owner = THIS_MODULE
 662 };
 663
 664 static int create_device(struct ramzswap *rzs, int device_id)
 665 {
 666         int ret = 0;
 667
 668         mutex_init(&rzs->lock);
 669         spin_lock_init(&rzs->stat64_lock);
 670
 671         rzs->queue = blk_alloc_queue(GFP_KERNEL);
 672         if (!rzs->queue) {
 673                 pr_err("Error allocating disk queue for device %d\n",
 674                         device_id);
 675                 ret = -ENOMEM;
 676                 goto out;
 677         }
 678
 679         blk_queue_make_request(rzs->queue, ramzswap_make_request);
 680         rzs->queue->queuedata = rzs;
 681
 682          /* gendisk structure */
 683         rzs->disk = alloc_disk(1);
 684         if (!rzs->disk) {
 685                 blk_cleanup_queue(rzs->queue);
 686                 pr_warning("Error allocating disk structure for device %d\n",
 687                         device_id);
 688                 ret = -ENOMEM;
 689                 goto out;
 690         }
 691
 692         rzs->disk->major = ramzswap_major;
 693         rzs->disk->first_minor = device_id;
 694         rzs->disk->fops = &ramzswap_devops;
 695         rzs->disk->queue = rzs->queue;
 696         rzs->disk->private_data = rzs;
 697         snprintf(rzs->disk->disk_name, 16, "ramzswap%d", device_id);
 698
 699         /* Actual capacity set using RZSIO_SET_DISKSIZE_KB ioctl */
 700         set_capacity(rzs->disk, 0);
 701
 702         /*
 703          * To ensure that we always get PAGE_SIZE aligned
 704          * and n*PAGE_SIZED sized I/O requests.
 705          */
 706         blk_queue_physical_block_size(rzs->disk->queue, PAGE_SIZE);
 707         blk_queue_logical_block_size(rzs->disk->queue, PAGE_SIZE);
 708         blk_queue_io_min(rzs->disk->queue, PAGE_SIZE);
 709         blk_queue_io_opt(rzs->disk->queue, PAGE_SIZE);
 710
 711         add_disk(rzs->disk);
 712
 713         rzs->init_done = 0;
 714
 715 out:
 716         return ret;
 717 }
 718
 719 static void destroy_device(struct ramzswap *rzs)
 720 {
 721         if (rzs->disk) {
 722                 del_gendisk(rzs->disk);
 723                 put_disk(rzs->disk);
 724         }
 725
 726         if (rzs->queue)
 727                 blk_cleanup_queue(rzs->queue);
 728 }
 729
 730 static int __init ramzswap_init(void)
 731 {
 732         int ret, dev_id;
 733
 734         if (num_devices > max_num_devices) {
 735                 pr_warning("Invalid value for num_devices: %u\n",
 736                                 num_devices);
 737                 ret = -EINVAL;
 738                 goto out;
 739         }
 740
 741         ramzswap_major = register_blkdev(0, "ramzswap");
 742         if (ramzswap_major <= 0) {
 743                 pr_warning("Unable to get major number\n");
 744                 ret = -EBUSY;
 745                 goto out;
 746         }
 747
 748         if (!num_devices) {
 749                 pr_info("num_devices not specified. Using default: 1\n");
 750                 num_devices = 1;
 751         }
 752
 753         /* Allocate the device array and initialize each one */
 754         pr_info("Creating %u devices ...\n", num_devices);
 755         devices = kzalloc(num_devices * sizeof(struct ramzswap), GFP_KERNEL);
 756         if (!devices) {
 757                 ret = -ENOMEM;
 758                 goto unregister;
 759         }
 760
 761         for (dev_id = 0; dev_id < num_devices; dev_id++) {
 762                 ret = create_device(&devices[dev_id], dev_id);
 763                 if (ret)
 764                         goto free_devices;
 765         }
 766
 767         return 0;
 768
 769 free_devices:
 770         while (dev_id)
 771                 destroy_device(&devices[--dev_id]);
 772 unregister:
 773         unregister_blkdev(ramzswap_major, "ramzswap");
 774 out:
 775         return ret;
 776 }
 777
 778 static void __exit ramzswap_exit(void)
 779 {
 780         int i;
 781         struct ramzswap *rzs;
 782
 783         for (i = 0; i < num_devices; i++) {
 784                 rzs = &devices[i];
 785
 786                 destroy_device(rzs);
 787                 if (rzs->init_done)
 788                         reset_device(rzs);
 789         }
 790
 791         unregister_blkdev(ramzswap_major, "ramzswap");
 792
 793         kfree(devices);
 794         pr_debug("Cleanup done!\n");
 795 }
 796
 797 module_param(num_devices, uint, 0);
 798 MODULE_PARM_DESC(num_devices, "Number of ramzswap devices");
 799
 800 module_init(ramzswap_init);
 801 module_exit(ramzswap_exit);
 802
 803 MODULE_LICENSE("Dual BSD/GPL");
 804 MODULE_AUTHOR("Nitin Gupta <ngupta@vflare.org>");
 805 MODULE_DESCRIPTION("Compressed RAM Based Swap Device");