fs/block_dev.c

   1 /*
   2  *  linux/fs/block_dev.c
   3  *
   4  *  Copyright (C) 1991, 1992  Linus Torvalds
   5  *  Copyright (C) 2001  Andrea Arcangeli <andrea@suse.de> SuSE
   6  */
   7
   8 #include <linux/config.h>
   9 #include <linux/init.h>
  10 #include <linux/mm.h>
  11 #include <linux/fcntl.h>
  12 #include <linux/slab.h>
  13 #include <linux/kmod.h>
  14 #include <linux/major.h>
  15 #include <linux/devfs_fs_kernel.h>
  16 #include <linux/smp_lock.h>
  17 #include <linux/highmem.h>
  18 #include <linux/blkdev.h>
  19 #include <linux/module.h>
  20 #include <linux/blkpg.h>
  21 #include <linux/buffer_head.h>
  22 #include <linux/mpage.h>
  23 #include <linux/mount.h>
  24 #include <linux/uio.h>
  25 #include <linux/namei.h>
  26 #include <asm/uaccess.h>
  27
  28
  29 static sector_t max_block(struct block_device *bdev)
  30 {
  31         sector_t retval = ~((sector_t)0);
  32         loff_t sz = bdev->bd_inode->i_size;
  33
  34         if (sz) {
  35                 unsigned int size = block_size(bdev);
  36                 unsigned int sizebits = blksize_bits(size);
  37                 retval = (sz >> sizebits);
  38         }
  39         return retval;
  40 }
  41
  42 /* Kill _all_ buffers, dirty or not.. */
  43 static void kill_bdev(struct block_device *bdev)
  44 {
  45         invalidate_bdev(bdev, 1);
  46         truncate_inode_pages(bdev->bd_inode->i_mapping, 0);
  47 }
  48
  49 int set_blocksize(struct block_device *bdev, int size)
  50 {
  51         int oldsize;
  52
  53         /* Size must be a power of two, and between 512 and PAGE_SIZE */
  54         if (size > PAGE_SIZE || size < 512 || (size & (size-1)))
  55                 return -EINVAL;
  56
  57         /* Size cannot be smaller than the size supported by the device */
  58         if (size < bdev_hardsect_size(bdev))
  59                 return -EINVAL;
  60
  61         oldsize = bdev->bd_block_size;
  62         if (oldsize == size)
  63                 return 0;
  64
  65         /* Ok, we're actually changing the blocksize.. */
  66         sync_blockdev(bdev);
  67         bdev->bd_block_size = size;
  68         bdev->bd_inode->i_blkbits = blksize_bits(size);
  69         kill_bdev(bdev);
  70         return 0;
  71 }
  72
  73 int sb_set_blocksize(struct super_block *sb, int size)
  74 {
  75         int bits;
  76         if (set_blocksize(sb->s_bdev, size) < 0)
  77                 return 0;
  78         sb->s_blocksize = size;
  79         for (bits = 9, size >>= 9; size >>= 1; bits++)
  80                 ;
  81         sb->s_blocksize_bits = bits;
  82         return sb->s_blocksize;
  83 }
  84
  85 int sb_min_blocksize(struct super_block *sb, int size)
  86 {
  87         int minsize = bdev_hardsect_size(sb->s_bdev);
  88         if (size < minsize)
  89                 size = minsize;
  90         return sb_set_blocksize(sb, size);
  91 }
  92
  93 static int
  94 blkdev_get_block(struct inode *inode, sector_t iblock,
  95                 struct buffer_head *bh, int create)
  96 {
  97         if (iblock >= max_block(inode->i_bdev))
  98                 return -EIO;
  99
 100         bh->b_bdev = inode->i_bdev;
 101         bh->b_blocknr = iblock;
 102         set_buffer_mapped(bh);
 103         return 0;
 104 }
 105
 106 static int
 107 blkdev_get_blocks(struct inode *inode, sector_t iblock,
 108                 unsigned long max_blocks, struct buffer_head *bh, int create)
 109 {
 110         if ((iblock + max_blocks) > max_block(inode->i_bdev))
 111                 return -EIO;
 112
 113         bh->b_bdev = inode->i_bdev;
 114         bh->b_blocknr = iblock;
 115         bh->b_size = max_blocks << inode->i_blkbits;
 116         set_buffer_mapped(bh);
 117         return 0;
 118 }
 119
 120 static int
 121 blkdev_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov,
 122                         loff_t offset, unsigned long nr_segs)
 123 {
 124         struct file *file = iocb->ki_filp;
 125         struct inode *inode = file->f_dentry->d_inode->i_mapping->host;
 126
 127         return blockdev_direct_IO(rw, iocb, inode, inode->i_bdev, iov, offset,
 128                                 nr_segs, blkdev_get_blocks);
 129 }
 130
 131 static int blkdev_writepage(struct page *page, struct writeback_control *wbc)
 132 {
 133         return block_write_full_page(page, blkdev_get_block, wbc);
 134 }
 135
 136 static int blkdev_readpage(struct file * file, struct page * page)
 137 {
 138         return block_read_full_page(page, blkdev_get_block);
 139 }
 140
 141 static int blkdev_prepare_write(struct file *file, struct page *page, unsigned from, unsigned to)
 142 {
 143         return block_prepare_write(page, from, to, blkdev_get_block);
 144 }
 145
 146 static int blkdev_commit_write(struct file *file, struct page *page, unsigned from, unsigned to)
 147 {
 148         return block_commit_write(page, from, to);
 149 }
 150
 151 /*
 152  * private llseek:
 153  * for a block special file file->f_dentry->d_inode->i_size is zero
 154  * so we compute the size by hand (just as in block_read/write above)
 155  */
 156 static loff_t block_llseek(struct file *file, loff_t offset, int origin)
 157 {
 158         /* ewww */
 159         loff_t size = file->f_dentry->d_inode->i_bdev->bd_inode->i_size;
 160         loff_t retval;
 161
 162         lock_kernel();
 163
 164         switch (origin) {
 165                 case 2:
 166                         offset += size;
 167                         break;
 168                 case 1:
 169                         offset += file->f_pos;
 170         }
 171         retval = -EINVAL;
 172         if (offset >= 0 && offset <= size) {
 173                 if (offset != file->f_pos) {
 174                         file->f_pos = offset;
 175                 }
 176                 retval = offset;
 177         }
 178         unlock_kernel();
 179         return retval;
 180 }
 181
 182 /*
 183  *      Filp may be NULL when we are called by an msync of a vma
 184  *      since the vma has no handle.
 185  */
 186
 187 static int block_fsync(struct file *filp, struct dentry *dentry, int datasync)
 188 {
 189         struct inode * inode = dentry->d_inode;
 190
 191         return sync_blockdev(inode->i_bdev);
 192 }
 193
 194 /*
 195  * pseudo-fs
 196  */
 197
 198 static struct super_block *bd_get_sb(struct file_system_type *fs_type,
 199         int flags, const char *dev_name, void *data)
 200 {
 201         return get_sb_pseudo(fs_type, "bdev:", NULL, 0x62646576);
 202 }
 203
 204 static struct file_system_type bd_type = {
 205         .name           = "bdev",
 206         .get_sb         = bd_get_sb,
 207         .kill_sb        = kill_anon_super,
 208 };
 209
 210 static struct vfsmount *bd_mnt;
 211 struct super_block *blockdev_superblock;
 212
 213 /*
 214  * bdev cache handling - shamelessly stolen from inode.c
 215  * We use smaller hashtable, though.
 216  */
 217
 218 #define HASH_BITS       6
 219 #define HASH_SIZE       (1UL << HASH_BITS)
 220 #define HASH_MASK       (HASH_SIZE-1)
 221 static struct list_head bdev_hashtable[HASH_SIZE];
 222 static spinlock_t bdev_lock __cacheline_aligned_in_smp = SPIN_LOCK_UNLOCKED;
 223 static kmem_cache_t * bdev_cachep;
 224
 225 #define alloc_bdev() \
 226          ((struct block_device *) kmem_cache_alloc(bdev_cachep, SLAB_KERNEL))
 227 #define destroy_bdev(bdev) kmem_cache_free(bdev_cachep, (bdev))
 228
 229 static void init_once(void * foo, kmem_cache_t * cachep, unsigned long flags)
 230 {
 231         struct block_device * bdev = (struct block_device *) foo;
 232
 233         if ((flags & (SLAB_CTOR_VERIFY|SLAB_CTOR_CONSTRUCTOR)) ==
 234             SLAB_CTOR_CONSTRUCTOR)
 235         {
 236                 memset(bdev, 0, sizeof(*bdev));
 237                 sema_init(&bdev->bd_sem, 1);
 238                 INIT_LIST_HEAD(&bdev->bd_inodes);
 239         }
 240 }
 241
 242 void __init bdev_cache_init(void)
 243 {
 244         int i, err;
 245         struct list_head *head = bdev_hashtable;
 246
 247         i = HASH_SIZE;
 248         do {
 249                 INIT_LIST_HEAD(head);
 250                 head++;
 251                 i--;
 252         } while (i);
 253
 254         bdev_cachep = kmem_cache_create("bdev_cache",
 255                                          sizeof(struct block_device),
 256                                          0, SLAB_HWCACHE_ALIGN, init_once,
 257                                          NULL);
 258         if (!bdev_cachep)
 259                 panic("Cannot create bdev_cache SLAB cache");
 260         err = register_filesystem(&bd_type);
 261         if (err)
 262                 panic("Cannot register bdev pseudo-fs");
 263         bd_mnt = kern_mount(&bd_type);
 264         err = PTR_ERR(bd_mnt);
 265         if (IS_ERR(bd_mnt))
 266                 panic("Cannot create bdev pseudo-fs");
 267         blockdev_superblock = bd_mnt->mnt_sb;   /* For writeback */
 268 }
 269
 270 /*
 271  * Most likely _very_ bad one - but then it's hardly critical for small
 272  * /dev and can be fixed when somebody will need really large one.
 273  */
 274 static inline unsigned long hash(dev_t dev)
 275 {
 276         unsigned long tmp = dev;
 277         tmp = tmp + (tmp >> HASH_BITS) + (tmp >> HASH_BITS*2);
 278         return tmp & HASH_MASK;
 279 }
 280
 281 static struct block_device *bdfind(dev_t dev, struct list_head *head)
 282 {
 283         struct list_head *p;
 284         struct block_device *bdev;
 285         list_for_each(p, head) {
 286                 bdev = list_entry(p, struct block_device, bd_hash);
 287                 if (bdev->bd_dev != dev)
 288                         continue;
 289                 atomic_inc(&bdev->bd_count);
 290                 return bdev;
 291         }
 292         return NULL;
 293 }
 294
 295 struct block_device *bdget(dev_t dev)
 296 {
 297         struct list_head * head = bdev_hashtable + hash(dev);
 298         struct block_device *bdev, *new_bdev;
 299         spin_lock(&bdev_lock);
 300         bdev = bdfind(dev, head);
 301         spin_unlock(&bdev_lock);
 302         if (bdev)
 303                 return bdev;
 304         new_bdev = alloc_bdev();
 305         if (new_bdev) {
 306                 struct inode *inode = new_inode(bd_mnt->mnt_sb);
 307                 if (inode) {
 308                         kdev_t kdev = to_kdev_t(dev);
 309
 310                         atomic_set(&new_bdev->bd_count,1);
 311                         new_bdev->bd_dev = dev;
 312                         new_bdev->bd_contains = NULL;
 313                         new_bdev->bd_inode = inode;
 314                         new_bdev->bd_block_size = (1 << inode->i_blkbits);
 315                         new_bdev->bd_part_count = 0;
 316                         new_bdev->bd_invalidated = 0;
 317                         inode->i_mode = S_IFBLK;
 318                         inode->i_rdev = kdev;
 319                         inode->i_bdev = new_bdev;
 320                         inode->i_data.a_ops = &def_blk_aops;
 321                         inode->i_data.gfp_mask = GFP_USER;
 322                         inode->i_data.backing_dev_info = &default_backing_dev_info;
 323                         spin_lock(&bdev_lock);
 324                         bdev = bdfind(dev, head);
 325                         if (!bdev) {
 326                                 list_add(&new_bdev->bd_hash, head);
 327                                 spin_unlock(&bdev_lock);
 328                                 return new_bdev;
 329                         }
 330                         spin_unlock(&bdev_lock);
 331                         iput(new_bdev->bd_inode);
 332                 }
 333                 destroy_bdev(new_bdev);
 334         }
 335         return bdev;
 336 }
 337
 338 long nr_blockdev_pages(void)
 339 {
 340         long ret = 0;
 341         int i;
 342
 343         spin_lock(&bdev_lock);
 344         for (i = 0; i < ARRAY_SIZE(bdev_hashtable); i++) {
 345                 struct list_head *head = &bdev_hashtable[i];
 346                 struct list_head *lh;
 347
 348                 if (head == NULL)
 349                         continue;
 350                 list_for_each(lh, head) {
 351                         struct block_device *bdev;
 352
 353                         bdev = list_entry(lh, struct block_device, bd_hash);
 354                         ret += bdev->bd_inode->i_mapping->nrpages;
 355                 }
 356         }
 357         spin_unlock(&bdev_lock);
 358         return ret;
 359 }
 360
 361 static inline void __bd_forget(struct inode *inode)
 362 {
 363         list_del_init(&inode->i_devices);
 364         inode->i_bdev = NULL;
 365         inode->i_mapping = &inode->i_data;
 366 }
 367
 368 void bdput(struct block_device *bdev)
 369 {
 370         if (atomic_dec_and_lock(&bdev->bd_count, &bdev_lock)) {
 371                 struct list_head *p;
 372                 if (bdev->bd_openers)
 373                         BUG();
 374                 list_del(&bdev->bd_hash);
 375                 while ( (p = bdev->bd_inodes.next) != &bdev->bd_inodes ) {
 376                         __bd_forget(list_entry(p, struct inode, i_devices));
 377                 }
 378                 spin_unlock(&bdev_lock);
 379                 iput(bdev->bd_inode);
 380                 destroy_bdev(bdev);
 381         }
 382 }
 383
 384 int bd_acquire(struct inode *inode)
 385 {
 386         struct block_device *bdev;
 387         spin_lock(&bdev_lock);
 388         if (inode->i_bdev) {
 389                 atomic_inc(&inode->i_bdev->bd_count);
 390                 spin_unlock(&bdev_lock);
 391                 return 0;
 392         }
 393         spin_unlock(&bdev_lock);
 394         bdev = bdget(kdev_t_to_nr(inode->i_rdev));
 395         if (!bdev)
 396                 return -ENOMEM;
 397         spin_lock(&bdev_lock);
 398         if (!inode->i_bdev) {
 399                 inode->i_bdev = bdev;
 400                 inode->i_mapping = bdev->bd_inode->i_mapping;
 401                 list_add(&inode->i_devices, &bdev->bd_inodes);
 402         } else if (inode->i_bdev != bdev)
 403                 BUG();
 404         spin_unlock(&bdev_lock);
 405         return 0;
 406 }
 407
 408 /* Call when you free inode */
 409
 410 void bd_forget(struct inode *inode)
 411 {
 412         spin_lock(&bdev_lock);
 413         if (inode->i_bdev)
 414                 __bd_forget(inode);
 415         spin_unlock(&bdev_lock);
 416 }
 417
 418 int bd_claim(struct block_device *bdev, void *holder)
 419 {
 420         int res = -EBUSY;
 421         spin_lock(&bdev_lock);
 422         if (!bdev->bd_holder || bdev->bd_holder == holder) {
 423                 bdev->bd_holder = holder;
 424                 bdev->bd_holders++;
 425                 res = 0;
 426         }
 427         spin_unlock(&bdev_lock);
 428         return res;
 429 }
 430
 431 void bd_release(struct block_device *bdev)
 432 {
 433         spin_lock(&bdev_lock);
 434         if (!--bdev->bd_holders)
 435                 bdev->bd_holder = NULL;
 436         spin_unlock(&bdev_lock);
 437 }
 438
 439 /*
 440  * Tries to open block device by device number.  Use it ONLY if you
 441  * really do not have anything better - i.e. when you are behind a
 442  * truly sucky interface and all you are given is a device number.  _Never_
 443  * to be used for internal purposes.  If you ever need it - reconsider
 444  * your API.
 445  */
 446 struct block_device *open_by_devnum(dev_t dev, unsigned mode, int kind)
 447 {
 448         struct block_device *bdev = bdget(dev);
 449         int err = -ENOMEM;
 450         int flags = mode & FMODE_WRITE ? O_RDWR : O_RDONLY;
 451         if (bdev)
 452                 err = blkdev_get(bdev, mode, flags, kind);
 453         return err ? ERR_PTR(err) : bdev;
 454 }
 455
 456 /*
 457  * This routine checks whether a removable media has been changed,
 458  * and invalidates all buffer-cache-entries in that case. This
 459  * is a relatively slow routine, so we have to try to minimize using
 460  * it. Thus it is called only upon a 'mount' or 'open'. This
 461  * is the best way of combining speed and utility, I think.
 462  * People changing diskettes in the middle of an operation deserve
 463  * to lose :-)
 464  */
 465 int check_disk_change(struct block_device *bdev)
 466 {
 467         struct gendisk *disk = bdev->bd_disk;
 468         struct block_device_operations * bdops = disk->fops;
 469
 470         if (!bdops->media_changed)
 471                 return 0;
 472         if (!bdops->media_changed(bdev->bd_disk))
 473                 return 0;
 474
 475         if (__invalidate_device(bdev, 0))
 476                 printk("VFS: busy inodes on changed media.\n");
 477
 478         if (bdops->revalidate_disk)
 479                 bdops->revalidate_disk(bdev->bd_disk);
 480         if (bdev->bd_disk->minors > 1)
 481                 bdev->bd_invalidated = 1;
 482         return 1;
 483 }
 484
 485 static void bd_set_size(struct block_device *bdev, loff_t size)
 486 {
 487         unsigned bsize = bdev_hardsect_size(bdev);
 488         bdev->bd_inode->i_size = size;
 489         while (bsize < PAGE_CACHE_SIZE) {
 490                 if (size & bsize)
 491                         break;
 492                 bsize <<= 1;
 493         }
 494         bdev->bd_block_size = bsize;
 495         bdev->bd_inode->i_blkbits = blksize_bits(bsize);
 496 }
 497
 498 static int do_open(struct block_device *bdev, struct inode *inode, struct file *file)
 499 {
 500         struct module *owner = NULL;
 501         struct gendisk *disk;
 502         int ret = -ENXIO;
 503         int part;
 504
 505         lock_kernel();
 506         disk = get_gendisk(bdev->bd_dev, &part);
 507         if (!disk) {
 508                 unlock_kernel();
 509                 bdput(bdev);
 510                 return ret;
 511         }
 512         owner = disk->fops->owner;
 513
 514         down(&bdev->bd_sem);
 515         if (!bdev->bd_openers) {
 516                 bdev->bd_disk = disk;
 517                 bdev->bd_contains = bdev;
 518                 if (!part) {
 519                         struct backing_dev_info *bdi;
 520                         if (disk->fops->open) {
 521                                 ret = disk->fops->open(inode, file);
 522                                 if (ret)
 523                                         goto out_first;
 524                         }
 525                         bdev->bd_offset = 0;
 526                         if (!bdev->bd_openers) {
 527                                 bd_set_size(bdev,(loff_t)get_capacity(disk)<<9);
 528                                 bdi = blk_get_backing_dev_info(bdev);
 529                                 if (bdi == NULL)
 530                                         bdi = &default_backing_dev_info;
 531                                 bdev->bd_inode->i_data.backing_dev_info = bdi;
 532                         }
 533                         if (bdev->bd_invalidated)
 534                                 rescan_partitions(disk, bdev);
 535                 } else {
 536                         struct hd_struct *p;
 537                         struct block_device *whole;
 538                         whole = bdget_disk(disk, 0);
 539                         ret = -ENOMEM;
 540                         if (!whole)
 541                                 goto out_first;
 542                         ret = blkdev_get(whole, file->f_mode, file->f_flags, BDEV_RAW);
 543                         if (ret)
 544                                 goto out_first;
 545                         bdev->bd_contains = whole;
 546                         down(&whole->bd_sem);
 547                         whole->bd_part_count++;
 548                         p = disk->part[part - 1];
 549                         bdev->bd_inode->i_data.backing_dev_info =
 550                            whole->bd_inode->i_data.backing_dev_info;
 551                         if (!(disk->flags & GENHD_FL_UP) || !p || !p->nr_sects) {
 552                                 whole->bd_part_count--;
 553                                 up(&whole->bd_sem);
 554                                 ret = -ENXIO;
 555                                 goto out_first;
 556                         }
 557                         bdev->bd_offset = p->start_sect;
 558                         bd_set_size(bdev, (loff_t) p->nr_sects << 9);
 559                         up(&whole->bd_sem);
 560                 }
 561         } else {
 562                 put_disk(disk);
 563                 module_put(owner);
 564                 if (bdev->bd_contains == bdev) {
 565                         if (bdev->bd_disk->fops->open) {
 566                                 ret = bdev->bd_disk->fops->open(inode, file);
 567                                 if (ret)
 568                                         goto out;
 569                         }
 570                         if (bdev->bd_invalidated)
 571                                 rescan_partitions(bdev->bd_disk, bdev);
 572                 } else {
 573                         down(&bdev->bd_contains->bd_sem);
 574                         bdev->bd_contains->bd_part_count++;
 575                         up(&bdev->bd_contains->bd_sem);
 576                 }
 577         }
 578         bdev->bd_openers++;
 579         up(&bdev->bd_sem);
 580         unlock_kernel();
 581         return 0;
 582
 583 out_first:
 584         bdev->bd_disk = NULL;
 585         bdev->bd_inode->i_data.backing_dev_info = &default_backing_dev_info;
 586         if (bdev != bdev->bd_contains)
 587                 blkdev_put(bdev->bd_contains, BDEV_RAW);
 588         bdev->bd_contains = NULL;
 589         put_disk(disk);
 590         module_put(owner);
 591 out:
 592         up(&bdev->bd_sem);
 593         unlock_kernel();
 594         if (ret)
 595                 bdput(bdev);
 596         return ret;
 597 }
 598
 599 int blkdev_get(struct block_device *bdev, mode_t mode, unsigned flags, int kind)
 600 {
 601         /*
 602          * This crockload is due to bad choice of ->open() type.
 603          * It will go away.
 604          * For now, block device ->open() routine must _not_
 605          * examine anything in 'inode' argument except ->i_rdev.
 606          */
 607         struct file fake_file = {};
 608         struct dentry fake_dentry = {};
 609         fake_file.f_mode = mode;
 610         fake_file.f_flags = flags;
 611         fake_file.f_dentry = &fake_dentry;
 612         fake_dentry.d_inode = bdev->bd_inode;
 613
 614         return do_open(bdev, bdev->bd_inode, &fake_file);
 615 }
 616
 617 int blkdev_open(struct inode * inode, struct file * filp)
 618 {
 619         struct block_device *bdev;
 620
 621         /*
 622          * Preserve backwards compatibility and allow large file access
 623          * even if userspace doesn't ask for it explicitly. Some mkfs
 624          * binary needs it. We might want to drop this workaround
 625          * during an unstable branch.
 626          */
 627         filp->f_flags |= O_LARGEFILE;
 628
 629         bd_acquire(inode);
 630         bdev = inode->i_bdev;
 631
 632         return do_open(bdev, inode, filp);
 633 }
 634
 635 int blkdev_put(struct block_device *bdev, int kind)
 636 {
 637         int ret = 0;
 638         struct inode *bd_inode = bdev->bd_inode;
 639         struct gendisk *disk = bdev->bd_disk;
 640
 641         down(&bdev->bd_sem);
 642         lock_kernel();
 643         if (!--bdev->bd_openers) {
 644                 switch (kind) {
 645                 case BDEV_FILE:
 646                 case BDEV_FS:
 647                         sync_blockdev(bd_inode->i_bdev);
 648                         break;
 649                 }
 650                 kill_bdev(bdev);
 651         }
 652         if (bdev->bd_contains == bdev) {
 653                 if (disk->fops->release)
 654                         ret = disk->fops->release(bd_inode, NULL);
 655         } else {
 656                 down(&bdev->bd_contains->bd_sem);
 657                 bdev->bd_contains->bd_part_count--;
 658                 up(&bdev->bd_contains->bd_sem);
 659         }
 660         if (!bdev->bd_openers) {
 661                 struct module *owner = disk->fops->owner;
 662
 663                 put_disk(disk);
 664                 module_put(owner);
 665
 666                 bdev->bd_disk = NULL;
 667                 bdev->bd_inode->i_data.backing_dev_info = &default_backing_dev_info;
 668                 if (bdev != bdev->bd_contains) {
 669                         blkdev_put(bdev->bd_contains, BDEV_RAW);
 670                 }
 671                 bdev->bd_contains = NULL;
 672         }
 673         unlock_kernel();
 674         up(&bdev->bd_sem);
 675         bdput(bdev);
 676         return ret;
 677 }
 678
 679 int blkdev_close(struct inode * inode, struct file * filp)
 680 {
 681         return blkdev_put(inode->i_bdev, BDEV_FILE);
 682 }
 683
 684 static ssize_t blkdev_file_write(struct file *file, const char __user *buf,
 685                                    size_t count, loff_t *ppos)
 686 {
 687         struct iovec local_iov = { .iov_base = (void __user *)buf, .iov_len = count };
 688
 689         return generic_file_write_nolock(file, &local_iov, 1, ppos);
 690 }
 691
 692 static ssize_t blkdev_file_aio_write(struct kiocb *iocb, const char __user *buf,
 693                                    size_t count, loff_t pos)
 694 {
 695         struct iovec local_iov = { .iov_base = (void __user *)buf, .iov_len = count };
 696
 697         return generic_file_aio_write_nolock(iocb, &local_iov, 1, &iocb->ki_pos);
 698 }
 699
 700
 701 struct address_space_operations def_blk_aops = {
 702         .readpage       = blkdev_readpage,
 703         .writepage      = blkdev_writepage,
 704         .sync_page      = block_sync_page,
 705         .prepare_write  = blkdev_prepare_write,
 706         .commit_write   = blkdev_commit_write,
 707         .writepages     = generic_writepages,
 708         .direct_IO      = blkdev_direct_IO,
 709 };
 710
 711 struct file_operations def_blk_fops = {
 712         .open           = blkdev_open,
 713         .release        = blkdev_close,
 714         .llseek         = block_llseek,
 715         .read           = generic_file_read,
 716         .write          = blkdev_file_write,
 717         .aio_read       = generic_file_aio_read,
 718         .aio_write      = blkdev_file_aio_write,
 719         .mmap           = generic_file_mmap,
 720         .fsync          = block_fsync,
 721         .ioctl          = blkdev_ioctl,
 722         .readv          = generic_file_readv,
 723         .writev         = generic_file_writev,
 724         .sendfile       = generic_file_sendfile,
 725 };
 726
 727 int ioctl_by_bdev(struct block_device *bdev, unsigned cmd, unsigned long arg)
 728 {
 729         int res;
 730         mm_segment_t old_fs = get_fs();
 731         set_fs(KERNEL_DS);
 732         res = blkdev_ioctl(bdev->bd_inode, NULL, cmd, arg);
 733         set_fs(old_fs);
 734         return res;
 735 }
 736
 737 /**
 738  * lookup_bdev  - lookup a struct block_device by name
 739  *
 740  * @path:       special file representing the block device
 741  *
 742  * Get a reference to the blockdevice at @path in the current
 743  * namespace if possible and return it.  Return ERR_PTR(error)
 744  * otherwise.
 745  */
 746 struct block_device *lookup_bdev(const char *path)
 747 {
 748         struct block_device *bdev;
 749         struct inode *inode;
 750         struct nameidata nd;
 751         int error;
 752
 753         if (!path || !*path)
 754                 return ERR_PTR(-EINVAL);
 755
 756         error = path_lookup(path, LOOKUP_FOLLOW, &nd);
 757         if (error)
 758                 return ERR_PTR(error);
 759
 760         inode = nd.dentry->d_inode;
 761         error = -ENOTBLK;
 762         if (!S_ISBLK(inode->i_mode))
 763                 goto fail;
 764         error = -EACCES;
 765         if (nd.mnt->mnt_flags & MNT_NODEV)
 766                 goto fail;
 767         error = bd_acquire(inode);
 768         if (error)
 769                 goto fail;
 770         bdev = inode->i_bdev;
 771
 772 out:
 773         path_release(&nd);
 774         return bdev;
 775 fail:
 776         bdev = ERR_PTR(error);
 777         goto out;
 778 }
 779
 780 /**
 781  * open_bdev_excl  -  open a block device by name and set it up for use
 782  *
 783  * @path:       special file representing the block device
 784  * @flags:      %MS_RDONLY for opening read-only
 785  * @kind:       usage (same as the 4th paramter to blkdev_get)
 786  * @holder:     owner for exclusion
 787  *
 788  * Open the blockdevice described by the special file at @path, claim it
 789  * for the @holder and properly set it up for @kind usage.
 790  */
 791 struct block_device *open_bdev_excl(const char *path, int flags,
 792                                     int kind, void *holder)
 793 {
 794         struct block_device *bdev;
 795         mode_t mode = FMODE_READ;
 796         int error = 0;
 797
 798         bdev = lookup_bdev(path);
 799         if (IS_ERR(bdev))
 800                 return bdev;
 801
 802         if (!(flags & MS_RDONLY))
 803                 mode |= FMODE_WRITE;
 804         error = blkdev_get(bdev, mode, 0, kind);
 805         if (error)
 806                 return ERR_PTR(error);
 807         error = -EACCES;
 808         if (!(flags & MS_RDONLY) && bdev_read_only(bdev))
 809                 goto blkdev_put;
 810         error = bd_claim(bdev, holder);
 811         if (error)
 812                 goto blkdev_put;
 813
 814         return bdev;
 815
 816 blkdev_put:
 817         blkdev_put(bdev, BDEV_FS);
 818         return ERR_PTR(error);
 819 }
 820
 821 /**
 822  * close_bdev_excl  -  release a blockdevice openen by open_bdev_excl()
 823  *
 824  * @bdev:       blockdevice to close
 825  * @kind:       usage (same as the 4th paramter to blkdev_get)
 826  *
 827  * This is the counterpart to open_bdev_excl().
 828  */
 829 void close_bdev_excl(struct block_device *bdev, int kind)
 830 {
 831         bd_release(bdev);
 832         blkdev_put(bdev, kind);
 833 }