linux/fs/block_dev.c
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   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/init.h>
   9#include <linux/mm.h>
  10#include <linux/fcntl.h>
  11#include <linux/slab.h>
  12#include <linux/kmod.h>
  13#include <linux/major.h>
  14#include <linux/device_cgroup.h>
  15#include <linux/highmem.h>
  16#include <linux/blkdev.h>
  17#include <linux/backing-dev.h>
  18#include <linux/module.h>
  19#include <linux/blkpg.h>
  20#include <linux/magic.h>
  21#include <linux/dax.h>
  22#include <linux/buffer_head.h>
  23#include <linux/swap.h>
  24#include <linux/pagevec.h>
  25#include <linux/writeback.h>
  26#include <linux/mpage.h>
  27#include <linux/mount.h>
  28#include <linux/uio.h>
  29#include <linux/namei.h>
  30#include <linux/log2.h>
  31#include <linux/cleancache.h>
  32#include <linux/dax.h>
  33#include <linux/badblocks.h>
  34#include <linux/task_io_accounting_ops.h>
  35#include <linux/falloc.h>
  36#include <linux/uaccess.h>
  37#include "internal.h"
  38
  39struct bdev_inode {
  40        struct block_device bdev;
  41        struct inode vfs_inode;
  42};
  43
  44static const struct address_space_operations def_blk_aops;
  45
  46static inline struct bdev_inode *BDEV_I(struct inode *inode)
  47{
  48        return container_of(inode, struct bdev_inode, vfs_inode);
  49}
  50
  51struct block_device *I_BDEV(struct inode *inode)
  52{
  53        return &BDEV_I(inode)->bdev;
  54}
  55EXPORT_SYMBOL(I_BDEV);
  56
  57static void bdev_write_inode(struct block_device *bdev)
  58{
  59        struct inode *inode = bdev->bd_inode;
  60        int ret;
  61
  62        spin_lock(&inode->i_lock);
  63        while (inode->i_state & I_DIRTY) {
  64                spin_unlock(&inode->i_lock);
  65                ret = write_inode_now(inode, true);
  66                if (ret) {
  67                        char name[BDEVNAME_SIZE];
  68                        pr_warn_ratelimited("VFS: Dirty inode writeback failed "
  69                                            "for block device %s (err=%d).\n",
  70                                            bdevname(bdev, name), ret);
  71                }
  72                spin_lock(&inode->i_lock);
  73        }
  74        spin_unlock(&inode->i_lock);
  75}
  76
  77/* Kill _all_ buffers and pagecache , dirty or not.. */
  78void kill_bdev(struct block_device *bdev)
  79{
  80        struct address_space *mapping = bdev->bd_inode->i_mapping;
  81
  82        if (mapping->nrpages == 0 && mapping->nrexceptional == 0)
  83                return;
  84
  85        invalidate_bh_lrus();
  86        truncate_inode_pages(mapping, 0);
  87}       
  88EXPORT_SYMBOL(kill_bdev);
  89
  90/* Invalidate clean unused buffers and pagecache. */
  91void invalidate_bdev(struct block_device *bdev)
  92{
  93        struct address_space *mapping = bdev->bd_inode->i_mapping;
  94
  95        if (mapping->nrpages) {
  96                invalidate_bh_lrus();
  97                lru_add_drain_all();    /* make sure all lru add caches are flushed */
  98                invalidate_mapping_pages(mapping, 0, -1);
  99        }
 100        /* 99% of the time, we don't need to flush the cleancache on the bdev.
 101         * But, for the strange corners, lets be cautious
 102         */
 103        cleancache_invalidate_inode(mapping);
 104}
 105EXPORT_SYMBOL(invalidate_bdev);
 106
 107int set_blocksize(struct block_device *bdev, int size)
 108{
 109        /* Size must be a power of two, and between 512 and PAGE_SIZE */
 110        if (size > PAGE_SIZE || size < 512 || !is_power_of_2(size))
 111                return -EINVAL;
 112
 113        /* Size cannot be smaller than the size supported by the device */
 114        if (size < bdev_logical_block_size(bdev))
 115                return -EINVAL;
 116
 117        /* Don't change the size if it is same as current */
 118        if (bdev->bd_block_size != size) {
 119                sync_blockdev(bdev);
 120                bdev->bd_block_size = size;
 121                bdev->bd_inode->i_blkbits = blksize_bits(size);
 122                kill_bdev(bdev);
 123        }
 124        return 0;
 125}
 126
 127EXPORT_SYMBOL(set_blocksize);
 128
 129int sb_set_blocksize(struct super_block *sb, int size)
 130{
 131        if (set_blocksize(sb->s_bdev, size))
 132                return 0;
 133        /* If we get here, we know size is power of two
 134         * and it's value is between 512 and PAGE_SIZE */
 135        sb->s_blocksize = size;
 136        sb->s_blocksize_bits = blksize_bits(size);
 137        return sb->s_blocksize;
 138}
 139
 140EXPORT_SYMBOL(sb_set_blocksize);
 141
 142int sb_min_blocksize(struct super_block *sb, int size)
 143{
 144        int minsize = bdev_logical_block_size(sb->s_bdev);
 145        if (size < minsize)
 146                size = minsize;
 147        return sb_set_blocksize(sb, size);
 148}
 149
 150EXPORT_SYMBOL(sb_min_blocksize);
 151
 152static int
 153blkdev_get_block(struct inode *inode, sector_t iblock,
 154                struct buffer_head *bh, int create)
 155{
 156        bh->b_bdev = I_BDEV(inode);
 157        bh->b_blocknr = iblock;
 158        set_buffer_mapped(bh);
 159        return 0;
 160}
 161
 162static struct inode *bdev_file_inode(struct file *file)
 163{
 164        return file->f_mapping->host;
 165}
 166
 167static unsigned int dio_bio_write_op(struct kiocb *iocb)
 168{
 169        unsigned int op = REQ_OP_WRITE | REQ_SYNC | REQ_IDLE;
 170
 171        /* avoid the need for a I/O completion work item */
 172        if (iocb->ki_flags & IOCB_DSYNC)
 173                op |= REQ_FUA;
 174        return op;
 175}
 176
 177#define DIO_INLINE_BIO_VECS 4
 178
 179static void blkdev_bio_end_io_simple(struct bio *bio)
 180{
 181        struct task_struct *waiter = bio->bi_private;
 182
 183        WRITE_ONCE(bio->bi_private, NULL);
 184        wake_up_process(waiter);
 185}
 186
 187static ssize_t
 188__blkdev_direct_IO_simple(struct kiocb *iocb, struct iov_iter *iter,
 189                int nr_pages)
 190{
 191        struct file *file = iocb->ki_filp;
 192        struct block_device *bdev = I_BDEV(bdev_file_inode(file));
 193        struct bio_vec inline_vecs[DIO_INLINE_BIO_VECS], *vecs, *bvec;
 194        loff_t pos = iocb->ki_pos;
 195        bool should_dirty = false;
 196        struct bio bio;
 197        ssize_t ret;
 198        blk_qc_t qc;
 199        int i;
 200
 201        if ((pos | iov_iter_alignment(iter)) &
 202            (bdev_logical_block_size(bdev) - 1))
 203                return -EINVAL;
 204
 205        if (nr_pages <= DIO_INLINE_BIO_VECS)
 206                vecs = inline_vecs;
 207        else {
 208                vecs = kmalloc_array(nr_pages, sizeof(struct bio_vec),
 209                                     GFP_KERNEL);
 210                if (!vecs)
 211                        return -ENOMEM;
 212        }
 213
 214        bio_init(&bio, vecs, nr_pages);
 215        bio_set_dev(&bio, bdev);
 216        bio.bi_iter.bi_sector = pos >> 9;
 217        bio.bi_write_hint = iocb->ki_hint;
 218        bio.bi_private = current;
 219        bio.bi_end_io = blkdev_bio_end_io_simple;
 220        bio.bi_ioprio = iocb->ki_ioprio;
 221
 222        ret = bio_iov_iter_get_pages(&bio, iter);
 223        if (unlikely(ret))
 224                goto out;
 225        ret = bio.bi_iter.bi_size;
 226
 227        if (iov_iter_rw(iter) == READ) {
 228                bio.bi_opf = REQ_OP_READ;
 229                if (iter_is_iovec(iter))
 230                        should_dirty = true;
 231        } else {
 232                bio.bi_opf = dio_bio_write_op(iocb);
 233                task_io_account_write(ret);
 234        }
 235
 236        qc = submit_bio(&bio);
 237        for (;;) {
 238                set_current_state(TASK_UNINTERRUPTIBLE);
 239                if (!READ_ONCE(bio.bi_private))
 240                        break;
 241                if (!(iocb->ki_flags & IOCB_HIPRI) ||
 242                    !blk_poll(bdev_get_queue(bdev), qc))
 243                        io_schedule();
 244        }
 245        __set_current_state(TASK_RUNNING);
 246
 247        bio_for_each_segment_all(bvec, &bio, i) {
 248                if (should_dirty && !PageCompound(bvec->bv_page))
 249                        set_page_dirty_lock(bvec->bv_page);
 250                put_page(bvec->bv_page);
 251        }
 252
 253        if (unlikely(bio.bi_status))
 254                ret = blk_status_to_errno(bio.bi_status);
 255
 256out:
 257        if (vecs != inline_vecs)
 258                kfree(vecs);
 259
 260        bio_uninit(&bio);
 261
 262        return ret;
 263}
 264
 265struct blkdev_dio {
 266        union {
 267                struct kiocb            *iocb;
 268                struct task_struct      *waiter;
 269        };
 270        size_t                  size;
 271        atomic_t                ref;
 272        bool                    multi_bio : 1;
 273        bool                    should_dirty : 1;
 274        bool                    is_sync : 1;
 275        struct bio              bio;
 276};
 277
 278static struct bio_set blkdev_dio_pool;
 279
 280static void blkdev_bio_end_io(struct bio *bio)
 281{
 282        struct blkdev_dio *dio = bio->bi_private;
 283        bool should_dirty = dio->should_dirty;
 284
 285        if (dio->multi_bio && !atomic_dec_and_test(&dio->ref)) {
 286                if (bio->bi_status && !dio->bio.bi_status)
 287                        dio->bio.bi_status = bio->bi_status;
 288        } else {
 289                if (!dio->is_sync) {
 290                        struct kiocb *iocb = dio->iocb;
 291                        ssize_t ret;
 292
 293                        if (likely(!dio->bio.bi_status)) {
 294                                ret = dio->size;
 295                                iocb->ki_pos += ret;
 296                        } else {
 297                                ret = blk_status_to_errno(dio->bio.bi_status);
 298                        }
 299
 300                        dio->iocb->ki_complete(iocb, ret, 0);
 301                        bio_put(&dio->bio);
 302                } else {
 303                        struct task_struct *waiter = dio->waiter;
 304
 305                        WRITE_ONCE(dio->waiter, NULL);
 306                        wake_up_process(waiter);
 307                }
 308        }
 309
 310        if (should_dirty) {
 311                bio_check_pages_dirty(bio);
 312        } else {
 313                struct bio_vec *bvec;
 314                int i;
 315
 316                bio_for_each_segment_all(bvec, bio, i)
 317                        put_page(bvec->bv_page);
 318                bio_put(bio);
 319        }
 320}
 321
 322static ssize_t
 323__blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter, int nr_pages)
 324{
 325        struct file *file = iocb->ki_filp;
 326        struct inode *inode = bdev_file_inode(file);
 327        struct block_device *bdev = I_BDEV(inode);
 328        struct blk_plug plug;
 329        struct blkdev_dio *dio;
 330        struct bio *bio;
 331        bool is_read = (iov_iter_rw(iter) == READ), is_sync;
 332        loff_t pos = iocb->ki_pos;
 333        blk_qc_t qc = BLK_QC_T_NONE;
 334        int ret = 0;
 335
 336        if ((pos | iov_iter_alignment(iter)) &
 337            (bdev_logical_block_size(bdev) - 1))
 338                return -EINVAL;
 339
 340        bio = bio_alloc_bioset(GFP_KERNEL, nr_pages, &blkdev_dio_pool);
 341        bio_get(bio); /* extra ref for the completion handler */
 342
 343        dio = container_of(bio, struct blkdev_dio, bio);
 344        dio->is_sync = is_sync = is_sync_kiocb(iocb);
 345        if (dio->is_sync)
 346                dio->waiter = current;
 347        else
 348                dio->iocb = iocb;
 349
 350        dio->size = 0;
 351        dio->multi_bio = false;
 352        dio->should_dirty = is_read && iter_is_iovec(iter);
 353
 354        blk_start_plug(&plug);
 355        for (;;) {
 356                bio_set_dev(bio, bdev);
 357                bio->bi_iter.bi_sector = pos >> 9;
 358                bio->bi_write_hint = iocb->ki_hint;
 359                bio->bi_private = dio;
 360                bio->bi_end_io = blkdev_bio_end_io;
 361                bio->bi_ioprio = iocb->ki_ioprio;
 362
 363                ret = bio_iov_iter_get_pages(bio, iter);
 364                if (unlikely(ret)) {
 365                        bio->bi_status = BLK_STS_IOERR;
 366                        bio_endio(bio);
 367                        break;
 368                }
 369
 370                if (is_read) {
 371                        bio->bi_opf = REQ_OP_READ;
 372                        if (dio->should_dirty)
 373                                bio_set_pages_dirty(bio);
 374                } else {
 375                        bio->bi_opf = dio_bio_write_op(iocb);
 376                        task_io_account_write(bio->bi_iter.bi_size);
 377                }
 378
 379                dio->size += bio->bi_iter.bi_size;
 380                pos += bio->bi_iter.bi_size;
 381
 382                nr_pages = iov_iter_npages(iter, BIO_MAX_PAGES);
 383                if (!nr_pages) {
 384                        qc = submit_bio(bio);
 385                        break;
 386                }
 387
 388                if (!dio->multi_bio) {
 389                        dio->multi_bio = true;
 390                        atomic_set(&dio->ref, 2);
 391                } else {
 392                        atomic_inc(&dio->ref);
 393                }
 394
 395                submit_bio(bio);
 396                bio = bio_alloc(GFP_KERNEL, nr_pages);
 397        }
 398        blk_finish_plug(&plug);
 399
 400        if (!is_sync)
 401                return -EIOCBQUEUED;
 402
 403        for (;;) {
 404                set_current_state(TASK_UNINTERRUPTIBLE);
 405                if (!READ_ONCE(dio->waiter))
 406                        break;
 407
 408                if (!(iocb->ki_flags & IOCB_HIPRI) ||
 409                    !blk_poll(bdev_get_queue(bdev), qc))
 410                        io_schedule();
 411        }
 412        __set_current_state(TASK_RUNNING);
 413
 414        if (!ret)
 415                ret = blk_status_to_errno(dio->bio.bi_status);
 416        if (likely(!ret))
 417                ret = dio->size;
 418
 419        bio_put(&dio->bio);
 420        return ret;
 421}
 422
 423static ssize_t
 424blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter)
 425{
 426        int nr_pages;
 427
 428        nr_pages = iov_iter_npages(iter, BIO_MAX_PAGES + 1);
 429        if (!nr_pages)
 430                return 0;
 431        if (is_sync_kiocb(iocb) && nr_pages <= BIO_MAX_PAGES)
 432                return __blkdev_direct_IO_simple(iocb, iter, nr_pages);
 433
 434        return __blkdev_direct_IO(iocb, iter, min(nr_pages, BIO_MAX_PAGES));
 435}
 436
 437static __init int blkdev_init(void)
 438{
 439        return bioset_init(&blkdev_dio_pool, 4, offsetof(struct blkdev_dio, bio), BIOSET_NEED_BVECS);
 440}
 441module_init(blkdev_init);
 442
 443int __sync_blockdev(struct block_device *bdev, int wait)
 444{
 445        if (!bdev)
 446                return 0;
 447        if (!wait)
 448                return filemap_flush(bdev->bd_inode->i_mapping);
 449        return filemap_write_and_wait(bdev->bd_inode->i_mapping);
 450}
 451
 452/*
 453 * Write out and wait upon all the dirty data associated with a block
 454 * device via its mapping.  Does not take the superblock lock.
 455 */
 456int sync_blockdev(struct block_device *bdev)
 457{
 458        return __sync_blockdev(bdev, 1);
 459}
 460EXPORT_SYMBOL(sync_blockdev);
 461
 462/*
 463 * Write out and wait upon all dirty data associated with this
 464 * device.   Filesystem data as well as the underlying block
 465 * device.  Takes the superblock lock.
 466 */
 467int fsync_bdev(struct block_device *bdev)
 468{
 469        struct super_block *sb = get_super(bdev);
 470        if (sb) {
 471                int res = sync_filesystem(sb);
 472                drop_super(sb);
 473                return res;
 474        }
 475        return sync_blockdev(bdev);
 476}
 477EXPORT_SYMBOL(fsync_bdev);
 478
 479/**
 480 * freeze_bdev  --  lock a filesystem and force it into a consistent state
 481 * @bdev:       blockdevice to lock
 482 *
 483 * If a superblock is found on this device, we take the s_umount semaphore
 484 * on it to make sure nobody unmounts until the snapshot creation is done.
 485 * The reference counter (bd_fsfreeze_count) guarantees that only the last
 486 * unfreeze process can unfreeze the frozen filesystem actually when multiple
 487 * freeze requests arrive simultaneously. It counts up in freeze_bdev() and
 488 * count down in thaw_bdev(). When it becomes 0, thaw_bdev() will unfreeze
 489 * actually.
 490 */
 491struct super_block *freeze_bdev(struct block_device *bdev)
 492{
 493        struct super_block *sb;
 494        int error = 0;
 495
 496        mutex_lock(&bdev->bd_fsfreeze_mutex);
 497        if (++bdev->bd_fsfreeze_count > 1) {
 498                /*
 499                 * We don't even need to grab a reference - the first call
 500                 * to freeze_bdev grab an active reference and only the last
 501                 * thaw_bdev drops it.
 502                 */
 503                sb = get_super(bdev);
 504                if (sb)
 505                        drop_super(sb);
 506                mutex_unlock(&bdev->bd_fsfreeze_mutex);
 507                return sb;
 508        }
 509
 510        sb = get_active_super(bdev);
 511        if (!sb)
 512                goto out;
 513        if (sb->s_op->freeze_super)
 514                error = sb->s_op->freeze_super(sb);
 515        else
 516                error = freeze_super(sb);
 517        if (error) {
 518                deactivate_super(sb);
 519                bdev->bd_fsfreeze_count--;
 520                mutex_unlock(&bdev->bd_fsfreeze_mutex);
 521                return ERR_PTR(error);
 522        }
 523        deactivate_super(sb);
 524 out:
 525        sync_blockdev(bdev);
 526        mutex_unlock(&bdev->bd_fsfreeze_mutex);
 527        return sb;      /* thaw_bdev releases s->s_umount */
 528}
 529EXPORT_SYMBOL(freeze_bdev);
 530
 531/**
 532 * thaw_bdev  -- unlock filesystem
 533 * @bdev:       blockdevice to unlock
 534 * @sb:         associated superblock
 535 *
 536 * Unlocks the filesystem and marks it writeable again after freeze_bdev().
 537 */
 538int thaw_bdev(struct block_device *bdev, struct super_block *sb)
 539{
 540        int error = -EINVAL;
 541
 542        mutex_lock(&bdev->bd_fsfreeze_mutex);
 543        if (!bdev->bd_fsfreeze_count)
 544                goto out;
 545
 546        error = 0;
 547        if (--bdev->bd_fsfreeze_count > 0)
 548                goto out;
 549
 550        if (!sb)
 551                goto out;
 552
 553        if (sb->s_op->thaw_super)
 554                error = sb->s_op->thaw_super(sb);
 555        else
 556                error = thaw_super(sb);
 557        if (error)
 558                bdev->bd_fsfreeze_count++;
 559out:
 560        mutex_unlock(&bdev->bd_fsfreeze_mutex);
 561        return error;
 562}
 563EXPORT_SYMBOL(thaw_bdev);
 564
 565static int blkdev_writepage(struct page *page, struct writeback_control *wbc)
 566{
 567        return block_write_full_page(page, blkdev_get_block, wbc);
 568}
 569
 570static int blkdev_readpage(struct file * file, struct page * page)
 571{
 572        return block_read_full_page(page, blkdev_get_block);
 573}
 574
 575static int blkdev_readpages(struct file *file, struct address_space *mapping,
 576                        struct list_head *pages, unsigned nr_pages)
 577{
 578        return mpage_readpages(mapping, pages, nr_pages, blkdev_get_block);
 579}
 580
 581static int blkdev_write_begin(struct file *file, struct address_space *mapping,
 582                        loff_t pos, unsigned len, unsigned flags,
 583                        struct page **pagep, void **fsdata)
 584{
 585        return block_write_begin(mapping, pos, len, flags, pagep,
 586                                 blkdev_get_block);
 587}
 588
 589static int blkdev_write_end(struct file *file, struct address_space *mapping,
 590                        loff_t pos, unsigned len, unsigned copied,
 591                        struct page *page, void *fsdata)
 592{
 593        int ret;
 594        ret = block_write_end(file, mapping, pos, len, copied, page, fsdata);
 595
 596        unlock_page(page);
 597        put_page(page);
 598
 599        return ret;
 600}
 601
 602/*
 603 * private llseek:
 604 * for a block special file file_inode(file)->i_size is zero
 605 * so we compute the size by hand (just as in block_read/write above)
 606 */
 607static loff_t block_llseek(struct file *file, loff_t offset, int whence)
 608{
 609        struct inode *bd_inode = bdev_file_inode(file);
 610        loff_t retval;
 611
 612        inode_lock(bd_inode);
 613        retval = fixed_size_llseek(file, offset, whence, i_size_read(bd_inode));
 614        inode_unlock(bd_inode);
 615        return retval;
 616}
 617        
 618int blkdev_fsync(struct file *filp, loff_t start, loff_t end, int datasync)
 619{
 620        struct inode *bd_inode = bdev_file_inode(filp);
 621        struct block_device *bdev = I_BDEV(bd_inode);
 622        int error;
 623        
 624        error = file_write_and_wait_range(filp, start, end);
 625        if (error)
 626                return error;
 627
 628        /*
 629         * There is no need to serialise calls to blkdev_issue_flush with
 630         * i_mutex and doing so causes performance issues with concurrent
 631         * O_SYNC writers to a block device.
 632         */
 633        error = blkdev_issue_flush(bdev, GFP_KERNEL, NULL);
 634        if (error == -EOPNOTSUPP)
 635                error = 0;
 636
 637        return error;
 638}
 639EXPORT_SYMBOL(blkdev_fsync);
 640
 641/**
 642 * bdev_read_page() - Start reading a page from a block device
 643 * @bdev: The device to read the page from
 644 * @sector: The offset on the device to read the page to (need not be aligned)
 645 * @page: The page to read
 646 *
 647 * On entry, the page should be locked.  It will be unlocked when the page
 648 * has been read.  If the block driver implements rw_page synchronously,
 649 * that will be true on exit from this function, but it need not be.
 650 *
 651 * Errors returned by this function are usually "soft", eg out of memory, or
 652 * queue full; callers should try a different route to read this page rather
 653 * than propagate an error back up the stack.
 654 *
 655 * Return: negative errno if an error occurs, 0 if submission was successful.
 656 */
 657int bdev_read_page(struct block_device *bdev, sector_t sector,
 658                        struct page *page)
 659{
 660        const struct block_device_operations *ops = bdev->bd_disk->fops;
 661        int result = -EOPNOTSUPP;
 662
 663        if (!ops->rw_page || bdev_get_integrity(bdev))
 664                return result;
 665
 666        result = blk_queue_enter(bdev->bd_queue, 0);
 667        if (result)
 668                return result;
 669        result = ops->rw_page(bdev, sector + get_start_sect(bdev), page,
 670                              REQ_OP_READ);
 671        blk_queue_exit(bdev->bd_queue);
 672        return result;
 673}
 674EXPORT_SYMBOL_GPL(bdev_read_page);
 675
 676/**
 677 * bdev_write_page() - Start writing a page to a block device
 678 * @bdev: The device to write the page to
 679 * @sector: The offset on the device to write the page to (need not be aligned)
 680 * @page: The page to write
 681 * @wbc: The writeback_control for the write
 682 *
 683 * On entry, the page should be locked and not currently under writeback.
 684 * On exit, if the write started successfully, the page will be unlocked and
 685 * under writeback.  If the write failed already (eg the driver failed to
 686 * queue the page to the device), the page will still be locked.  If the
 687 * caller is a ->writepage implementation, it will need to unlock the page.
 688 *
 689 * Errors returned by this function are usually "soft", eg out of memory, or
 690 * queue full; callers should try a different route to write this page rather
 691 * than propagate an error back up the stack.
 692 *
 693 * Return: negative errno if an error occurs, 0 if submission was successful.
 694 */
 695int bdev_write_page(struct block_device *bdev, sector_t sector,
 696                        struct page *page, struct writeback_control *wbc)
 697{
 698        int result;
 699        const struct block_device_operations *ops = bdev->bd_disk->fops;
 700
 701        if (!ops->rw_page || bdev_get_integrity(bdev))
 702                return -EOPNOTSUPP;
 703        result = blk_queue_enter(bdev->bd_queue, 0);
 704        if (result)
 705                return result;
 706
 707        set_page_writeback(page);
 708        result = ops->rw_page(bdev, sector + get_start_sect(bdev), page,
 709                              REQ_OP_WRITE);
 710        if (result) {
 711                end_page_writeback(page);
 712        } else {
 713                clean_page_buffers(page);
 714                unlock_page(page);
 715        }
 716        blk_queue_exit(bdev->bd_queue);
 717        return result;
 718}
 719EXPORT_SYMBOL_GPL(bdev_write_page);
 720
 721/*
 722 * pseudo-fs
 723 */
 724
 725static  __cacheline_aligned_in_smp DEFINE_SPINLOCK(bdev_lock);
 726static struct kmem_cache * bdev_cachep __read_mostly;
 727
 728static struct inode *bdev_alloc_inode(struct super_block *sb)
 729{
 730        struct bdev_inode *ei = kmem_cache_alloc(bdev_cachep, GFP_KERNEL);
 731        if (!ei)
 732                return NULL;
 733        return &ei->vfs_inode;
 734}
 735
 736static void bdev_i_callback(struct rcu_head *head)
 737{
 738        struct inode *inode = container_of(head, struct inode, i_rcu);
 739        struct bdev_inode *bdi = BDEV_I(inode);
 740
 741        kmem_cache_free(bdev_cachep, bdi);
 742}
 743
 744static void bdev_destroy_inode(struct inode *inode)
 745{
 746        call_rcu(&inode->i_rcu, bdev_i_callback);
 747}
 748
 749static void init_once(void *foo)
 750{
 751        struct bdev_inode *ei = (struct bdev_inode *) foo;
 752        struct block_device *bdev = &ei->bdev;
 753
 754        memset(bdev, 0, sizeof(*bdev));
 755        mutex_init(&bdev->bd_mutex);
 756        INIT_LIST_HEAD(&bdev->bd_list);
 757#ifdef CONFIG_SYSFS
 758        INIT_LIST_HEAD(&bdev->bd_holder_disks);
 759#endif
 760        bdev->bd_bdi = &noop_backing_dev_info;
 761        inode_init_once(&ei->vfs_inode);
 762        /* Initialize mutex for freeze. */
 763        mutex_init(&bdev->bd_fsfreeze_mutex);
 764}
 765
 766static void bdev_evict_inode(struct inode *inode)
 767{
 768        struct block_device *bdev = &BDEV_I(inode)->bdev;
 769        truncate_inode_pages_final(&inode->i_data);
 770        invalidate_inode_buffers(inode); /* is it needed here? */
 771        clear_inode(inode);
 772        spin_lock(&bdev_lock);
 773        list_del_init(&bdev->bd_list);
 774        spin_unlock(&bdev_lock);
 775        /* Detach inode from wb early as bdi_put() may free bdi->wb */
 776        inode_detach_wb(inode);
 777        if (bdev->bd_bdi != &noop_backing_dev_info) {
 778                bdi_put(bdev->bd_bdi);
 779                bdev->bd_bdi = &noop_backing_dev_info;
 780        }
 781}
 782
 783static const struct super_operations bdev_sops = {
 784        .statfs = simple_statfs,
 785        .alloc_inode = bdev_alloc_inode,
 786        .destroy_inode = bdev_destroy_inode,
 787        .drop_inode = generic_delete_inode,
 788        .evict_inode = bdev_evict_inode,
 789};
 790
 791static struct dentry *bd_mount(struct file_system_type *fs_type,
 792        int flags, const char *dev_name, void *data)
 793{
 794        struct dentry *dent;
 795        dent = mount_pseudo(fs_type, "bdev:", &bdev_sops, NULL, BDEVFS_MAGIC);
 796        if (!IS_ERR(dent))
 797                dent->d_sb->s_iflags |= SB_I_CGROUPWB;
 798        return dent;
 799}
 800
 801static struct file_system_type bd_type = {
 802        .name           = "bdev",
 803        .mount          = bd_mount,
 804        .kill_sb        = kill_anon_super,
 805};
 806
 807struct super_block *blockdev_superblock __read_mostly;
 808EXPORT_SYMBOL_GPL(blockdev_superblock);
 809
 810void __init bdev_cache_init(void)
 811{
 812        int err;
 813        static struct vfsmount *bd_mnt;
 814
 815        bdev_cachep = kmem_cache_create("bdev_cache", sizeof(struct bdev_inode),
 816                        0, (SLAB_HWCACHE_ALIGN|SLAB_RECLAIM_ACCOUNT|
 817                                SLAB_MEM_SPREAD|SLAB_ACCOUNT|SLAB_PANIC),
 818                        init_once);
 819        err = register_filesystem(&bd_type);
 820        if (err)
 821                panic("Cannot register bdev pseudo-fs");
 822        bd_mnt = kern_mount(&bd_type);
 823        if (IS_ERR(bd_mnt))
 824                panic("Cannot create bdev pseudo-fs");
 825        blockdev_superblock = bd_mnt->mnt_sb;   /* For writeback */
 826}
 827
 828/*
 829 * Most likely _very_ bad one - but then it's hardly critical for small
 830 * /dev and can be fixed when somebody will need really large one.
 831 * Keep in mind that it will be fed through icache hash function too.
 832 */
 833static inline unsigned long hash(dev_t dev)
 834{
 835        return MAJOR(dev)+MINOR(dev);
 836}
 837
 838static int bdev_test(struct inode *inode, void *data)
 839{
 840        return BDEV_I(inode)->bdev.bd_dev == *(dev_t *)data;
 841}
 842
 843static int bdev_set(struct inode *inode, void *data)
 844{
 845        BDEV_I(inode)->bdev.bd_dev = *(dev_t *)data;
 846        return 0;
 847}
 848
 849static LIST_HEAD(all_bdevs);
 850
 851/*
 852 * If there is a bdev inode for this device, unhash it so that it gets evicted
 853 * as soon as last inode reference is dropped.
 854 */
 855void bdev_unhash_inode(dev_t dev)
 856{
 857        struct inode *inode;
 858
 859        inode = ilookup5(blockdev_superblock, hash(dev), bdev_test, &dev);
 860        if (inode) {
 861                remove_inode_hash(inode);
 862                iput(inode);
 863        }
 864}
 865
 866struct block_device *bdget(dev_t dev)
 867{
 868        struct block_device *bdev;
 869        struct inode *inode;
 870
 871        inode = iget5_locked(blockdev_superblock, hash(dev),
 872                        bdev_test, bdev_set, &dev);
 873
 874        if (!inode)
 875                return NULL;
 876
 877        bdev = &BDEV_I(inode)->bdev;
 878
 879        if (inode->i_state & I_NEW) {
 880                bdev->bd_contains = NULL;
 881                bdev->bd_super = NULL;
 882                bdev->bd_inode = inode;
 883                bdev->bd_block_size = i_blocksize(inode);
 884                bdev->bd_part_count = 0;
 885                bdev->bd_invalidated = 0;
 886                inode->i_mode = S_IFBLK;
 887                inode->i_rdev = dev;
 888                inode->i_bdev = bdev;
 889                inode->i_data.a_ops = &def_blk_aops;
 890                mapping_set_gfp_mask(&inode->i_data, GFP_USER);
 891                spin_lock(&bdev_lock);
 892                list_add(&bdev->bd_list, &all_bdevs);
 893                spin_unlock(&bdev_lock);
 894                unlock_new_inode(inode);
 895        }
 896        return bdev;
 897}
 898
 899EXPORT_SYMBOL(bdget);
 900
 901/**
 902 * bdgrab -- Grab a reference to an already referenced block device
 903 * @bdev:       Block device to grab a reference to.
 904 */
 905struct block_device *bdgrab(struct block_device *bdev)
 906{
 907        ihold(bdev->bd_inode);
 908        return bdev;
 909}
 910EXPORT_SYMBOL(bdgrab);
 911
 912long nr_blockdev_pages(void)
 913{
 914        struct block_device *bdev;
 915        long ret = 0;
 916        spin_lock(&bdev_lock);
 917        list_for_each_entry(bdev, &all_bdevs, bd_list) {
 918                ret += bdev->bd_inode->i_mapping->nrpages;
 919        }
 920        spin_unlock(&bdev_lock);
 921        return ret;
 922}
 923
 924void bdput(struct block_device *bdev)
 925{
 926        iput(bdev->bd_inode);
 927}
 928
 929EXPORT_SYMBOL(bdput);
 930 
 931static struct block_device *bd_acquire(struct inode *inode)
 932{
 933        struct block_device *bdev;
 934
 935        spin_lock(&bdev_lock);
 936        bdev = inode->i_bdev;
 937        if (bdev && !inode_unhashed(bdev->bd_inode)) {
 938                bdgrab(bdev);
 939                spin_unlock(&bdev_lock);
 940                return bdev;
 941        }
 942        spin_unlock(&bdev_lock);
 943
 944        /*
 945         * i_bdev references block device inode that was already shut down
 946         * (corresponding device got removed).  Remove the reference and look
 947         * up block device inode again just in case new device got
 948         * reestablished under the same device number.
 949         */
 950        if (bdev)
 951                bd_forget(inode);
 952
 953        bdev = bdget(inode->i_rdev);
 954        if (bdev) {
 955                spin_lock(&bdev_lock);
 956                if (!inode->i_bdev) {
 957                        /*
 958                         * We take an additional reference to bd_inode,
 959                         * and it's released in clear_inode() of inode.
 960                         * So, we can access it via ->i_mapping always
 961                         * without igrab().
 962                         */
 963                        bdgrab(bdev);
 964                        inode->i_bdev = bdev;
 965                        inode->i_mapping = bdev->bd_inode->i_mapping;
 966                }
 967                spin_unlock(&bdev_lock);
 968        }
 969        return bdev;
 970}
 971
 972/* Call when you free inode */
 973
 974void bd_forget(struct inode *inode)
 975{
 976        struct block_device *bdev = NULL;
 977
 978        spin_lock(&bdev_lock);
 979        if (!sb_is_blkdev_sb(inode->i_sb))
 980                bdev = inode->i_bdev;
 981        inode->i_bdev = NULL;
 982        inode->i_mapping = &inode->i_data;
 983        spin_unlock(&bdev_lock);
 984
 985        if (bdev)
 986                bdput(bdev);
 987}
 988
 989/**
 990 * bd_may_claim - test whether a block device can be claimed
 991 * @bdev: block device of interest
 992 * @whole: whole block device containing @bdev, may equal @bdev
 993 * @holder: holder trying to claim @bdev
 994 *
 995 * Test whether @bdev can be claimed by @holder.
 996 *
 997 * CONTEXT:
 998 * spin_lock(&bdev_lock).
 999 *
1000 * RETURNS:
1001 * %true if @bdev can be claimed, %false otherwise.
1002 */
1003static bool bd_may_claim(struct block_device *bdev, struct block_device *whole,
1004                         void *holder)
1005{
1006        if (bdev->bd_holder == holder)
1007                return true;     /* already a holder */
1008        else if (bdev->bd_holder != NULL)
1009                return false;    /* held by someone else */
1010        else if (whole == bdev)
1011                return true;     /* is a whole device which isn't held */
1012
1013        else if (whole->bd_holder == bd_may_claim)
1014                return true;     /* is a partition of a device that is being partitioned */
1015        else if (whole->bd_holder != NULL)
1016                return false;    /* is a partition of a held device */
1017        else
1018                return true;     /* is a partition of an un-held device */
1019}
1020
1021/**
1022 * bd_prepare_to_claim - prepare to claim a block device
1023 * @bdev: block device of interest
1024 * @whole: the whole device containing @bdev, may equal @bdev
1025 * @holder: holder trying to claim @bdev
1026 *
1027 * Prepare to claim @bdev.  This function fails if @bdev is already
1028 * claimed by another holder and waits if another claiming is in
1029 * progress.  This function doesn't actually claim.  On successful
1030 * return, the caller has ownership of bd_claiming and bd_holder[s].
1031 *
1032 * CONTEXT:
1033 * spin_lock(&bdev_lock).  Might release bdev_lock, sleep and regrab
1034 * it multiple times.
1035 *
1036 * RETURNS:
1037 * 0 if @bdev can be claimed, -EBUSY otherwise.
1038 */
1039static int bd_prepare_to_claim(struct block_device *bdev,
1040                               struct block_device *whole, void *holder)
1041{
1042retry:
1043        /* if someone else claimed, fail */
1044        if (!bd_may_claim(bdev, whole, holder))
1045                return -EBUSY;
1046
1047        /* if claiming is already in progress, wait for it to finish */
1048        if (whole->bd_claiming) {
1049                wait_queue_head_t *wq = bit_waitqueue(&whole->bd_claiming, 0);
1050                DEFINE_WAIT(wait);
1051
1052                prepare_to_wait(wq, &wait, TASK_UNINTERRUPTIBLE);
1053                spin_unlock(&bdev_lock);
1054                schedule();
1055                finish_wait(wq, &wait);
1056                spin_lock(&bdev_lock);
1057                goto retry;
1058        }
1059
1060        /* yay, all mine */
1061        return 0;
1062}
1063
1064static struct gendisk *bdev_get_gendisk(struct block_device *bdev, int *partno)
1065{
1066        struct gendisk *disk = get_gendisk(bdev->bd_dev, partno);
1067
1068        if (!disk)
1069                return NULL;
1070        /*
1071         * Now that we hold gendisk reference we make sure bdev we looked up is
1072         * not stale. If it is, it means device got removed and created before
1073         * we looked up gendisk and we fail open in such case. Associating
1074         * unhashed bdev with newly created gendisk could lead to two bdevs
1075         * (and thus two independent caches) being associated with one device
1076         * which is bad.
1077         */
1078        if (inode_unhashed(bdev->bd_inode)) {
1079                put_disk_and_module(disk);
1080                return NULL;
1081        }
1082        return disk;
1083}
1084
1085/**
1086 * bd_start_claiming - start claiming a block device
1087 * @bdev: block device of interest
1088 * @holder: holder trying to claim @bdev
1089 *
1090 * @bdev is about to be opened exclusively.  Check @bdev can be opened
1091 * exclusively and mark that an exclusive open is in progress.  Each
1092 * successful call to this function must be matched with a call to
1093 * either bd_finish_claiming() or bd_abort_claiming() (which do not
1094 * fail).
1095 *
1096 * This function is used to gain exclusive access to the block device
1097 * without actually causing other exclusive open attempts to fail. It
1098 * should be used when the open sequence itself requires exclusive
1099 * access but may subsequently fail.
1100 *
1101 * CONTEXT:
1102 * Might sleep.
1103 *
1104 * RETURNS:
1105 * Pointer to the block device containing @bdev on success, ERR_PTR()
1106 * value on failure.
1107 */
1108static struct block_device *bd_start_claiming(struct block_device *bdev,
1109                                              void *holder)
1110{
1111        struct gendisk *disk;
1112        struct block_device *whole;
1113        int partno, err;
1114
1115        might_sleep();
1116
1117        /*
1118         * @bdev might not have been initialized properly yet, look up
1119         * and grab the outer block device the hard way.
1120         */
1121        disk = bdev_get_gendisk(bdev, &partno);
1122        if (!disk)
1123                return ERR_PTR(-ENXIO);
1124
1125        /*
1126         * Normally, @bdev should equal what's returned from bdget_disk()
1127         * if partno is 0; however, some drivers (floppy) use multiple
1128         * bdev's for the same physical device and @bdev may be one of the
1129         * aliases.  Keep @bdev if partno is 0.  This means claimer
1130         * tracking is broken for those devices but it has always been that
1131         * way.
1132         */
1133        if (partno)
1134                whole = bdget_disk(disk, 0);
1135        else
1136                whole = bdgrab(bdev);
1137
1138        put_disk_and_module(disk);
1139        if (!whole)
1140                return ERR_PTR(-ENOMEM);
1141
1142        /* prepare to claim, if successful, mark claiming in progress */
1143        spin_lock(&bdev_lock);
1144
1145        err = bd_prepare_to_claim(bdev, whole, holder);
1146        if (err == 0) {
1147                whole->bd_claiming = holder;
1148                spin_unlock(&bdev_lock);
1149                return whole;
1150        } else {
1151                spin_unlock(&bdev_lock);
1152                bdput(whole);
1153                return ERR_PTR(err);
1154        }
1155}
1156
1157#ifdef CONFIG_SYSFS
1158struct bd_holder_disk {
1159        struct list_head        list;
1160        struct gendisk          *disk;
1161        int                     refcnt;
1162};
1163
1164static struct bd_holder_disk *bd_find_holder_disk(struct block_device *bdev,
1165                                                  struct gendisk *disk)
1166{
1167        struct bd_holder_disk *holder;
1168
1169        list_for_each_entry(holder, &bdev->bd_holder_disks, list)
1170                if (holder->disk == disk)
1171                        return holder;
1172        return NULL;
1173}
1174
1175static int add_symlink(struct kobject *from, struct kobject *to)
1176{
1177        return sysfs_create_link(from, to, kobject_name(to));
1178}
1179
1180static void del_symlink(struct kobject *from, struct kobject *to)
1181{
1182        sysfs_remove_link(from, kobject_name(to));
1183}
1184
1185/**
1186 * bd_link_disk_holder - create symlinks between holding disk and slave bdev
1187 * @bdev: the claimed slave bdev
1188 * @disk: the holding disk
1189 *
1190 * DON'T USE THIS UNLESS YOU'RE ALREADY USING IT.
1191 *
1192 * This functions creates the following sysfs symlinks.
1193 *
1194 * - from "slaves" directory of the holder @disk to the claimed @bdev
1195 * - from "holders" directory of the @bdev to the holder @disk
1196 *
1197 * For example, if /dev/dm-0 maps to /dev/sda and disk for dm-0 is
1198 * passed to bd_link_disk_holder(), then:
1199 *
1200 *   /sys/block/dm-0/slaves/sda --> /sys/block/sda
1201 *   /sys/block/sda/holders/dm-0 --> /sys/block/dm-0
1202 *
1203 * The caller must have claimed @bdev before calling this function and
1204 * ensure that both @bdev and @disk are valid during the creation and
1205 * lifetime of these symlinks.
1206 *
1207 * CONTEXT:
1208 * Might sleep.
1209 *
1210 * RETURNS:
1211 * 0 on success, -errno on failure.
1212 */
1213int bd_link_disk_holder(struct block_device *bdev, struct gendisk *disk)
1214{
1215        struct bd_holder_disk *holder;
1216        int ret = 0;
1217
1218        mutex_lock(&bdev->bd_mutex);
1219
1220        WARN_ON_ONCE(!bdev->bd_holder);
1221
1222        /* FIXME: remove the following once add_disk() handles errors */
1223        if (WARN_ON(!disk->slave_dir || !bdev->bd_part->holder_dir))
1224                goto out_unlock;
1225
1226        holder = bd_find_holder_disk(bdev, disk);
1227        if (holder) {
1228                holder->refcnt++;
1229                goto out_unlock;
1230        }
1231
1232        holder = kzalloc(sizeof(*holder), GFP_KERNEL);
1233        if (!holder) {
1234                ret = -ENOMEM;
1235                goto out_unlock;
1236        }
1237
1238        INIT_LIST_HEAD(&holder->list);
1239        holder->disk = disk;
1240        holder->refcnt = 1;
1241
1242        ret = add_symlink(disk->slave_dir, &part_to_dev(bdev->bd_part)->kobj);
1243        if (ret)
1244                goto out_free;
1245
1246        ret = add_symlink(bdev->bd_part->holder_dir, &disk_to_dev(disk)->kobj);
1247        if (ret)
1248                goto out_del;
1249        /*
1250         * bdev could be deleted beneath us which would implicitly destroy
1251         * the holder directory.  Hold on to it.
1252         */
1253        kobject_get(bdev->bd_part->holder_dir);
1254
1255        list_add(&holder->list, &bdev->bd_holder_disks);
1256        goto out_unlock;
1257
1258out_del:
1259        del_symlink(disk->slave_dir, &part_to_dev(bdev->bd_part)->kobj);
1260out_free:
1261        kfree(holder);
1262out_unlock:
1263        mutex_unlock(&bdev->bd_mutex);
1264        return ret;
1265}
1266EXPORT_SYMBOL_GPL(bd_link_disk_holder);
1267
1268/**
1269 * bd_unlink_disk_holder - destroy symlinks created by bd_link_disk_holder()
1270 * @bdev: the calimed slave bdev
1271 * @disk: the holding disk
1272 *
1273 * DON'T USE THIS UNLESS YOU'RE ALREADY USING IT.
1274 *
1275 * CONTEXT:
1276 * Might sleep.
1277 */
1278void bd_unlink_disk_holder(struct block_device *bdev, struct gendisk *disk)
1279{
1280        struct bd_holder_disk *holder;
1281
1282        mutex_lock(&bdev->bd_mutex);
1283
1284        holder = bd_find_holder_disk(bdev, disk);
1285
1286        if (!WARN_ON_ONCE(holder == NULL) && !--holder->refcnt) {
1287                del_symlink(disk->slave_dir, &part_to_dev(bdev->bd_part)->kobj);
1288                del_symlink(bdev->bd_part->holder_dir,
1289                            &disk_to_dev(disk)->kobj);
1290                kobject_put(bdev->bd_part->holder_dir);
1291                list_del_init(&holder->list);
1292                kfree(holder);
1293        }
1294
1295        mutex_unlock(&bdev->bd_mutex);
1296}
1297EXPORT_SYMBOL_GPL(bd_unlink_disk_holder);
1298#endif
1299
1300/**
1301 * flush_disk - invalidates all buffer-cache entries on a disk
1302 *
1303 * @bdev:      struct block device to be flushed
1304 * @kill_dirty: flag to guide handling of dirty inodes
1305 *
1306 * Invalidates all buffer-cache entries on a disk. It should be called
1307 * when a disk has been changed -- either by a media change or online
1308 * resize.
1309 */
1310static void flush_disk(struct block_device *bdev, bool kill_dirty)
1311{
1312        if (__invalidate_device(bdev, kill_dirty)) {
1313                printk(KERN_WARNING "VFS: busy inodes on changed media or "
1314                       "resized disk %s\n",
1315                       bdev->bd_disk ? bdev->bd_disk->disk_name : "");
1316        }
1317
1318        if (!bdev->bd_disk)
1319                return;
1320        if (disk_part_scan_enabled(bdev->bd_disk))
1321                bdev->bd_invalidated = 1;
1322}
1323
1324/**
1325 * check_disk_size_change - checks for disk size change and adjusts bdev size.
1326 * @disk: struct gendisk to check
1327 * @bdev: struct bdev to adjust.
1328 * @verbose: if %true log a message about a size change if there is any
1329 *
1330 * This routine checks to see if the bdev size does not match the disk size
1331 * and adjusts it if it differs. When shrinking the bdev size, its all caches
1332 * are freed.
1333 */
1334void check_disk_size_change(struct gendisk *disk, struct block_device *bdev,
1335                bool verbose)
1336{
1337        loff_t disk_size, bdev_size;
1338
1339        disk_size = (loff_t)get_capacity(disk) << 9;
1340        bdev_size = i_size_read(bdev->bd_inode);
1341        if (disk_size != bdev_size) {
1342                if (verbose) {
1343                        printk(KERN_INFO
1344                               "%s: detected capacity change from %lld to %lld\n",
1345                               disk->disk_name, bdev_size, disk_size);
1346                }
1347                i_size_write(bdev->bd_inode, disk_size);
1348                if (bdev_size > disk_size)
1349                        flush_disk(bdev, false);
1350        }
1351}
1352
1353/**
1354 * revalidate_disk - wrapper for lower-level driver's revalidate_disk call-back
1355 * @disk: struct gendisk to be revalidated
1356 *
1357 * This routine is a wrapper for lower-level driver's revalidate_disk
1358 * call-backs.  It is used to do common pre and post operations needed
1359 * for all revalidate_disk operations.
1360 */
1361int revalidate_disk(struct gendisk *disk)
1362{
1363        struct block_device *bdev;
1364        int ret = 0;
1365
1366        if (disk->fops->revalidate_disk)
1367                ret = disk->fops->revalidate_disk(disk);
1368        bdev = bdget_disk(disk, 0);
1369        if (!bdev)
1370                return ret;
1371
1372        mutex_lock(&bdev->bd_mutex);
1373        check_disk_size_change(disk, bdev, ret == 0);
1374        bdev->bd_invalidated = 0;
1375        mutex_unlock(&bdev->bd_mutex);
1376        bdput(bdev);
1377        return ret;
1378}
1379EXPORT_SYMBOL(revalidate_disk);
1380
1381/*
1382 * This routine checks whether a removable media has been changed,
1383 * and invalidates all buffer-cache-entries in that case. This
1384 * is a relatively slow routine, so we have to try to minimize using
1385 * it. Thus it is called only upon a 'mount' or 'open'. This
1386 * is the best way of combining speed and utility, I think.
1387 * People changing diskettes in the middle of an operation deserve
1388 * to lose :-)
1389 */
1390int check_disk_change(struct block_device *bdev)
1391{
1392        struct gendisk *disk = bdev->bd_disk;
1393        const struct block_device_operations *bdops = disk->fops;
1394        unsigned int events;
1395
1396        events = disk_clear_events(disk, DISK_EVENT_MEDIA_CHANGE |
1397                                   DISK_EVENT_EJECT_REQUEST);
1398        if (!(events & DISK_EVENT_MEDIA_CHANGE))
1399                return 0;
1400
1401        flush_disk(bdev, true);
1402        if (bdops->revalidate_disk)
1403                bdops->revalidate_disk(bdev->bd_disk);
1404        return 1;
1405}
1406
1407EXPORT_SYMBOL(check_disk_change);
1408
1409void bd_set_size(struct block_device *bdev, loff_t size)
1410{
1411        unsigned bsize = bdev_logical_block_size(bdev);
1412
1413        inode_lock(bdev->bd_inode);
1414        i_size_write(bdev->bd_inode, size);
1415        inode_unlock(bdev->bd_inode);
1416        while (bsize < PAGE_SIZE) {
1417                if (size & bsize)
1418                        break;
1419                bsize <<= 1;
1420        }
1421        bdev->bd_block_size = bsize;
1422        bdev->bd_inode->i_blkbits = blksize_bits(bsize);
1423}
1424EXPORT_SYMBOL(bd_set_size);
1425
1426static void __blkdev_put(struct block_device *bdev, fmode_t mode, int for_part);
1427
1428/*
1429 * bd_mutex locking:
1430 *
1431 *  mutex_lock(part->bd_mutex)
1432 *    mutex_lock_nested(whole->bd_mutex, 1)
1433 */
1434
1435static int __blkdev_get(struct block_device *bdev, fmode_t mode, int for_part)
1436{
1437        struct gendisk *disk;
1438        int ret;
1439        int partno;
1440        int perm = 0;
1441        bool first_open = false;
1442
1443        if (mode & FMODE_READ)
1444                perm |= MAY_READ;
1445        if (mode & FMODE_WRITE)
1446                perm |= MAY_WRITE;
1447        /*
1448         * hooks: /n/, see "layering violations".
1449         */
1450        if (!for_part) {
1451                ret = devcgroup_inode_permission(bdev->bd_inode, perm);
1452                if (ret != 0) {
1453                        bdput(bdev);
1454                        return ret;
1455                }
1456        }
1457
1458 restart:
1459
1460        ret = -ENXIO;
1461        disk = bdev_get_gendisk(bdev, &partno);
1462        if (!disk)
1463                goto out;
1464
1465        disk_block_events(disk);
1466        mutex_lock_nested(&bdev->bd_mutex, for_part);
1467        if (!bdev->bd_openers) {
1468                first_open = true;
1469                bdev->bd_disk = disk;
1470                bdev->bd_queue = disk->queue;
1471                bdev->bd_contains = bdev;
1472                bdev->bd_partno = partno;
1473
1474                if (!partno) {
1475                        ret = -ENXIO;
1476                        bdev->bd_part = disk_get_part(disk, partno);
1477                        if (!bdev->bd_part)
1478                                goto out_clear;
1479
1480                        ret = 0;
1481                        if (disk->fops->open) {
1482                                ret = disk->fops->open(bdev, mode);
1483                                if (ret == -ERESTARTSYS) {
1484                                        /* Lost a race with 'disk' being
1485                                         * deleted, try again.
1486                                         * See md.c
1487                                         */
1488                                        disk_put_part(bdev->bd_part);
1489                                        bdev->bd_part = NULL;
1490                                        bdev->bd_disk = NULL;
1491                                        bdev->bd_queue = NULL;
1492                                        mutex_unlock(&bdev->bd_mutex);
1493                                        disk_unblock_events(disk);
1494                                        put_disk_and_module(disk);
1495                                        goto restart;
1496                                }
1497                        }
1498
1499                        if (!ret)
1500                                bd_set_size(bdev,(loff_t)get_capacity(disk)<<9);
1501
1502                        /*
1503                         * If the device is invalidated, rescan partition
1504                         * if open succeeded or failed with -ENOMEDIUM.
1505                         * The latter is necessary to prevent ghost
1506                         * partitions on a removed medium.
1507                         */
1508                        if (bdev->bd_invalidated) {
1509                                if (!ret)
1510                                        rescan_partitions(disk, bdev);
1511                                else if (ret == -ENOMEDIUM)
1512                                        invalidate_partitions(disk, bdev);
1513                        }
1514
1515                        if (ret)
1516                                goto out_clear;
1517                } else {
1518                        struct block_device *whole;
1519                        whole = bdget_disk(disk, 0);
1520                        ret = -ENOMEM;
1521                        if (!whole)
1522                                goto out_clear;
1523                        BUG_ON(for_part);
1524                        ret = __blkdev_get(whole, mode, 1);
1525                        if (ret)
1526                                goto out_clear;
1527                        bdev->bd_contains = whole;
1528                        bdev->bd_part = disk_get_part(disk, partno);
1529                        if (!(disk->flags & GENHD_FL_UP) ||
1530                            !bdev->bd_part || !bdev->bd_part->nr_sects) {
1531                                ret = -ENXIO;
1532                                goto out_clear;
1533                        }
1534                        bd_set_size(bdev, (loff_t)bdev->bd_part->nr_sects << 9);
1535                }
1536
1537                if (bdev->bd_bdi == &noop_backing_dev_info)
1538                        bdev->bd_bdi = bdi_get(disk->queue->backing_dev_info);
1539        } else {
1540                if (bdev->bd_contains == bdev) {
1541                        ret = 0;
1542                        if (bdev->bd_disk->fops->open)
1543                                ret = bdev->bd_disk->fops->open(bdev, mode);
1544                        /* the same as first opener case, read comment there */
1545                        if (bdev->bd_invalidated) {
1546                                if (!ret)
1547                                        rescan_partitions(bdev->bd_disk, bdev);
1548                                else if (ret == -ENOMEDIUM)
1549                                        invalidate_partitions(bdev->bd_disk, bdev);
1550                        }
1551                        if (ret)
1552                                goto out_unlock_bdev;
1553                }
1554        }
1555        bdev->bd_openers++;
1556        if (for_part)
1557                bdev->bd_part_count++;
1558        mutex_unlock(&bdev->bd_mutex);
1559        disk_unblock_events(disk);
1560        /* only one opener holds refs to the module and disk */
1561        if (!first_open)
1562                put_disk_and_module(disk);
1563        return 0;
1564
1565 out_clear:
1566        disk_put_part(bdev->bd_part);
1567        bdev->bd_disk = NULL;
1568        bdev->bd_part = NULL;
1569        bdev->bd_queue = NULL;
1570        if (bdev != bdev->bd_contains)
1571                __blkdev_put(bdev->bd_contains, mode, 1);
1572        bdev->bd_contains = NULL;
1573 out_unlock_bdev:
1574        mutex_unlock(&bdev->bd_mutex);
1575        disk_unblock_events(disk);
1576        put_disk_and_module(disk);
1577 out:
1578        bdput(bdev);
1579
1580        return ret;
1581}
1582
1583/**
1584 * blkdev_get - open a block device
1585 * @bdev: block_device to open
1586 * @mode: FMODE_* mask
1587 * @holder: exclusive holder identifier
1588 *
1589 * Open @bdev with @mode.  If @mode includes %FMODE_EXCL, @bdev is
1590 * open with exclusive access.  Specifying %FMODE_EXCL with %NULL
1591 * @holder is invalid.  Exclusive opens may nest for the same @holder.
1592 *
1593 * On success, the reference count of @bdev is unchanged.  On failure,
1594 * @bdev is put.
1595 *
1596 * CONTEXT:
1597 * Might sleep.
1598 *
1599 * RETURNS:
1600 * 0 on success, -errno on failure.
1601 */
1602int blkdev_get(struct block_device *bdev, fmode_t mode, void *holder)
1603{
1604        struct block_device *whole = NULL;
1605        int res;
1606
1607        WARN_ON_ONCE((mode & FMODE_EXCL) && !holder);
1608
1609        if ((mode & FMODE_EXCL) && holder) {
1610                whole = bd_start_claiming(bdev, holder);
1611                if (IS_ERR(whole)) {
1612                        bdput(bdev);
1613                        return PTR_ERR(whole);
1614                }
1615        }
1616
1617        res = __blkdev_get(bdev, mode, 0);
1618
1619        if (whole) {
1620                struct gendisk *disk = whole->bd_disk;
1621
1622                /* finish claiming */
1623                mutex_lock(&bdev->bd_mutex);
1624                spin_lock(&bdev_lock);
1625
1626                if (!res) {
1627                        BUG_ON(!bd_may_claim(bdev, whole, holder));
1628                        /*
1629                         * Note that for a whole device bd_holders
1630                         * will be incremented twice, and bd_holder
1631                         * will be set to bd_may_claim before being
1632                         * set to holder
1633                         */
1634                        whole->bd_holders++;
1635                        whole->bd_holder = bd_may_claim;
1636                        bdev->bd_holders++;
1637                        bdev->bd_holder = holder;
1638                }
1639
1640                /* tell others that we're done */
1641                BUG_ON(whole->bd_claiming != holder);
1642                whole->bd_claiming = NULL;
1643                wake_up_bit(&whole->bd_claiming, 0);
1644
1645                spin_unlock(&bdev_lock);
1646
1647                /*
1648                 * Block event polling for write claims if requested.  Any
1649                 * write holder makes the write_holder state stick until
1650                 * all are released.  This is good enough and tracking
1651                 * individual writeable reference is too fragile given the
1652                 * way @mode is used in blkdev_get/put().
1653                 */
1654                if (!res && (mode & FMODE_WRITE) && !bdev->bd_write_holder &&
1655                    (disk->flags & GENHD_FL_BLOCK_EVENTS_ON_EXCL_WRITE)) {
1656                        bdev->bd_write_holder = true;
1657                        disk_block_events(disk);
1658                }
1659
1660                mutex_unlock(&bdev->bd_mutex);
1661                bdput(whole);
1662        }
1663
1664        return res;
1665}
1666EXPORT_SYMBOL(blkdev_get);
1667
1668/**
1669 * blkdev_get_by_path - open a block device by name
1670 * @path: path to the block device to open
1671 * @mode: FMODE_* mask
1672 * @holder: exclusive holder identifier
1673 *
1674 * Open the blockdevice described by the device file at @path.  @mode
1675 * and @holder are identical to blkdev_get().
1676 *
1677 * On success, the returned block_device has reference count of one.
1678 *
1679 * CONTEXT:
1680 * Might sleep.
1681 *
1682 * RETURNS:
1683 * Pointer to block_device on success, ERR_PTR(-errno) on failure.
1684 */
1685struct block_device *blkdev_get_by_path(const char *path, fmode_t mode,
1686                                        void *holder)
1687{
1688        struct block_device *bdev;
1689        int err;
1690
1691        bdev = lookup_bdev(path);
1692        if (IS_ERR(bdev))
1693                return bdev;
1694
1695        err = blkdev_get(bdev, mode, holder);
1696        if (err)
1697                return ERR_PTR(err);
1698
1699        if ((mode & FMODE_WRITE) && bdev_read_only(bdev)) {
1700                blkdev_put(bdev, mode);
1701                return ERR_PTR(-EACCES);
1702        }
1703
1704        return bdev;
1705}
1706EXPORT_SYMBOL(blkdev_get_by_path);
1707
1708/**
1709 * blkdev_get_by_dev - open a block device by device number
1710 * @dev: device number of block device to open
1711 * @mode: FMODE_* mask
1712 * @holder: exclusive holder identifier
1713 *
1714 * Open the blockdevice described by device number @dev.  @mode and
1715 * @holder are identical to blkdev_get().
1716 *
1717 * Use it ONLY if you really do not have anything better - i.e. when
1718 * you are behind a truly sucky interface and all you are given is a
1719 * device number.  _Never_ to be used for internal purposes.  If you
1720 * ever need it - reconsider your API.
1721 *
1722 * On success, the returned block_device has reference count of one.
1723 *
1724 * CONTEXT:
1725 * Might sleep.
1726 *
1727 * RETURNS:
1728 * Pointer to block_device on success, ERR_PTR(-errno) on failure.
1729 */
1730struct block_device *blkdev_get_by_dev(dev_t dev, fmode_t mode, void *holder)
1731{
1732        struct block_device *bdev;
1733        int err;
1734
1735        bdev = bdget(dev);
1736        if (!bdev)
1737                return ERR_PTR(-ENOMEM);
1738
1739        err = blkdev_get(bdev, mode, holder);
1740        if (err)
1741                return ERR_PTR(err);
1742
1743        return bdev;
1744}
1745EXPORT_SYMBOL(blkdev_get_by_dev);
1746
1747static int blkdev_open(struct inode * inode, struct file * filp)
1748{
1749        struct block_device *bdev;
1750
1751        /*
1752         * Preserve backwards compatibility and allow large file access
1753         * even if userspace doesn't ask for it explicitly. Some mkfs
1754         * binary needs it. We might want to drop this workaround
1755         * during an unstable branch.
1756         */
1757        filp->f_flags |= O_LARGEFILE;
1758
1759        filp->f_mode |= FMODE_NOWAIT;
1760
1761        if (filp->f_flags & O_NDELAY)
1762                filp->f_mode |= FMODE_NDELAY;
1763        if (filp->f_flags & O_EXCL)
1764                filp->f_mode |= FMODE_EXCL;
1765        if ((filp->f_flags & O_ACCMODE) == 3)
1766                filp->f_mode |= FMODE_WRITE_IOCTL;
1767
1768        bdev = bd_acquire(inode);
1769        if (bdev == NULL)
1770                return -ENOMEM;
1771
1772        filp->f_mapping = bdev->bd_inode->i_mapping;
1773        filp->f_wb_err = filemap_sample_wb_err(filp->f_mapping);
1774
1775        return blkdev_get(bdev, filp->f_mode, filp);
1776}
1777
1778static void __blkdev_put(struct block_device *bdev, fmode_t mode, int for_part)
1779{
1780        struct gendisk *disk = bdev->bd_disk;
1781        struct block_device *victim = NULL;
1782
1783        mutex_lock_nested(&bdev->bd_mutex, for_part);
1784        if (for_part)
1785                bdev->bd_part_count--;
1786
1787        if (!--bdev->bd_openers) {
1788                WARN_ON_ONCE(bdev->bd_holders);
1789                sync_blockdev(bdev);
1790                kill_bdev(bdev);
1791
1792                bdev_write_inode(bdev);
1793        }
1794        if (bdev->bd_contains == bdev) {
1795                if (disk->fops->release)
1796                        disk->fops->release(disk, mode);
1797        }
1798        if (!bdev->bd_openers) {
1799                disk_put_part(bdev->bd_part);
1800                bdev->bd_part = NULL;
1801                bdev->bd_disk = NULL;
1802                if (bdev != bdev->bd_contains)
1803                        victim = bdev->bd_contains;
1804                bdev->bd_contains = NULL;
1805
1806                put_disk_and_module(disk);
1807        }
1808        mutex_unlock(&bdev->bd_mutex);
1809        bdput(bdev);
1810        if (victim)
1811                __blkdev_put(victim, mode, 1);
1812}
1813
1814void blkdev_put(struct block_device *bdev, fmode_t mode)
1815{
1816        mutex_lock(&bdev->bd_mutex);
1817
1818        if (mode & FMODE_EXCL) {
1819                bool bdev_free;
1820
1821                /*
1822                 * Release a claim on the device.  The holder fields
1823                 * are protected with bdev_lock.  bd_mutex is to
1824                 * synchronize disk_holder unlinking.
1825                 */
1826                spin_lock(&bdev_lock);
1827
1828                WARN_ON_ONCE(--bdev->bd_holders < 0);
1829                WARN_ON_ONCE(--bdev->bd_contains->bd_holders < 0);
1830
1831                /* bd_contains might point to self, check in a separate step */
1832                if ((bdev_free = !bdev->bd_holders))
1833                        bdev->bd_holder = NULL;
1834                if (!bdev->bd_contains->bd_holders)
1835                        bdev->bd_contains->bd_holder = NULL;
1836
1837                spin_unlock(&bdev_lock);
1838
1839                /*
1840                 * If this was the last claim, remove holder link and
1841                 * unblock evpoll if it was a write holder.
1842                 */
1843                if (bdev_free && bdev->bd_write_holder) {
1844                        disk_unblock_events(bdev->bd_disk);
1845                        bdev->bd_write_holder = false;
1846                }
1847        }
1848
1849        /*
1850         * Trigger event checking and tell drivers to flush MEDIA_CHANGE
1851         * event.  This is to ensure detection of media removal commanded
1852         * from userland - e.g. eject(1).
1853         */
1854        disk_flush_events(bdev->bd_disk, DISK_EVENT_MEDIA_CHANGE);
1855
1856        mutex_unlock(&bdev->bd_mutex);
1857
1858        __blkdev_put(bdev, mode, 0);
1859}
1860EXPORT_SYMBOL(blkdev_put);
1861
1862static int blkdev_close(struct inode * inode, struct file * filp)
1863{
1864        struct block_device *bdev = I_BDEV(bdev_file_inode(filp));
1865        blkdev_put(bdev, filp->f_mode);
1866        return 0;
1867}
1868
1869static long block_ioctl(struct file *file, unsigned cmd, unsigned long arg)
1870{
1871        struct block_device *bdev = I_BDEV(bdev_file_inode(file));
1872        fmode_t mode = file->f_mode;
1873
1874        /*
1875         * O_NDELAY can be altered using fcntl(.., F_SETFL, ..), so we have
1876         * to updated it before every ioctl.
1877         */
1878        if (file->f_flags & O_NDELAY)
1879                mode |= FMODE_NDELAY;
1880        else
1881                mode &= ~FMODE_NDELAY;
1882
1883        return blkdev_ioctl(bdev, mode, cmd, arg);
1884}
1885
1886/*
1887 * Write data to the block device.  Only intended for the block device itself
1888 * and the raw driver which basically is a fake block device.
1889 *
1890 * Does not take i_mutex for the write and thus is not for general purpose
1891 * use.
1892 */
1893ssize_t blkdev_write_iter(struct kiocb *iocb, struct iov_iter *from)
1894{
1895        struct file *file = iocb->ki_filp;
1896        struct inode *bd_inode = bdev_file_inode(file);
1897        loff_t size = i_size_read(bd_inode);
1898        struct blk_plug plug;
1899        ssize_t ret;
1900
1901        if (bdev_read_only(I_BDEV(bd_inode)))
1902                return -EPERM;
1903
1904        if (!iov_iter_count(from))
1905                return 0;
1906
1907        if (iocb->ki_pos >= size)
1908                return -ENOSPC;
1909
1910        if ((iocb->ki_flags & (IOCB_NOWAIT | IOCB_DIRECT)) == IOCB_NOWAIT)
1911                return -EOPNOTSUPP;
1912
1913        iov_iter_truncate(from, size - iocb->ki_pos);
1914
1915        blk_start_plug(&plug);
1916        ret = __generic_file_write_iter(iocb, from);
1917        if (ret > 0)
1918                ret = generic_write_sync(iocb, ret);
1919        blk_finish_plug(&plug);
1920        return ret;
1921}
1922EXPORT_SYMBOL_GPL(blkdev_write_iter);
1923
1924ssize_t blkdev_read_iter(struct kiocb *iocb, struct iov_iter *to)
1925{
1926        struct file *file = iocb->ki_filp;
1927        struct inode *bd_inode = bdev_file_inode(file);
1928        loff_t size = i_size_read(bd_inode);
1929        loff_t pos = iocb->ki_pos;
1930
1931        if (pos >= size)
1932                return 0;
1933
1934        size -= pos;
1935        iov_iter_truncate(to, size);
1936        return generic_file_read_iter(iocb, to);
1937}
1938EXPORT_SYMBOL_GPL(blkdev_read_iter);
1939
1940/*
1941 * Try to release a page associated with block device when the system
1942 * is under memory pressure.
1943 */
1944static int blkdev_releasepage(struct page *page, gfp_t wait)
1945{
1946        struct super_block *super = BDEV_I(page->mapping->host)->bdev.bd_super;
1947
1948        if (super && super->s_op->bdev_try_to_free_page)
1949                return super->s_op->bdev_try_to_free_page(super, page, wait);
1950
1951        return try_to_free_buffers(page);
1952}
1953
1954static int blkdev_writepages(struct address_space *mapping,
1955                             struct writeback_control *wbc)
1956{
1957        return generic_writepages(mapping, wbc);
1958}
1959
1960static const struct address_space_operations def_blk_aops = {
1961        .readpage       = blkdev_readpage,
1962        .readpages      = blkdev_readpages,
1963        .writepage      = blkdev_writepage,
1964        .write_begin    = blkdev_write_begin,
1965        .write_end      = blkdev_write_end,
1966        .writepages     = blkdev_writepages,
1967        .releasepage    = blkdev_releasepage,
1968        .direct_IO      = blkdev_direct_IO,
1969        .is_dirty_writeback = buffer_check_dirty_writeback,
1970};
1971
1972#define BLKDEV_FALLOC_FL_SUPPORTED                                      \
1973                (FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE |           \
1974                 FALLOC_FL_ZERO_RANGE | FALLOC_FL_NO_HIDE_STALE)
1975
1976static long blkdev_fallocate(struct file *file, int mode, loff_t start,
1977                             loff_t len)
1978{
1979        struct block_device *bdev = I_BDEV(bdev_file_inode(file));
1980        struct address_space *mapping;
1981        loff_t end = start + len - 1;
1982        loff_t isize;
1983        int error;
1984
1985        /* Fail if we don't recognize the flags. */
1986        if (mode & ~BLKDEV_FALLOC_FL_SUPPORTED)
1987                return -EOPNOTSUPP;
1988
1989        /* Don't go off the end of the device. */
1990        isize = i_size_read(bdev->bd_inode);
1991        if (start >= isize)
1992                return -EINVAL;
1993        if (end >= isize) {
1994                if (mode & FALLOC_FL_KEEP_SIZE) {
1995                        len = isize - start;
1996                        end = start + len - 1;
1997                } else
1998                        return -EINVAL;
1999        }
2000
2001        /*
2002         * Don't allow IO that isn't aligned to logical block size.
2003         */
2004        if ((start | len) & (bdev_logical_block_size(bdev) - 1))
2005                return -EINVAL;
2006
2007        /* Invalidate the page cache, including dirty pages. */
2008        mapping = bdev->bd_inode->i_mapping;
2009        truncate_inode_pages_range(mapping, start, end);
2010
2011        switch (mode) {
2012        case FALLOC_FL_ZERO_RANGE:
2013        case FALLOC_FL_ZERO_RANGE | FALLOC_FL_KEEP_SIZE:
2014                error = blkdev_issue_zeroout(bdev, start >> 9, len >> 9,
2015                                            GFP_KERNEL, BLKDEV_ZERO_NOUNMAP);
2016                break;
2017        case FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE:
2018                error = blkdev_issue_zeroout(bdev, start >> 9, len >> 9,
2019                                             GFP_KERNEL, BLKDEV_ZERO_NOFALLBACK);
2020                break;
2021        case FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE | FALLOC_FL_NO_HIDE_STALE:
2022                error = blkdev_issue_discard(bdev, start >> 9, len >> 9,
2023                                             GFP_KERNEL, 0);
2024                break;
2025        default:
2026                return -EOPNOTSUPP;
2027        }
2028        if (error)
2029                return error;
2030
2031        /*
2032         * Invalidate again; if someone wandered in and dirtied a page,
2033         * the caller will be given -EBUSY.  The third argument is
2034         * inclusive, so the rounding here is safe.
2035         */
2036        return invalidate_inode_pages2_range(mapping,
2037                                             start >> PAGE_SHIFT,
2038                                             end >> PAGE_SHIFT);
2039}
2040
2041const struct file_operations def_blk_fops = {
2042        .open           = blkdev_open,
2043        .release        = blkdev_close,
2044        .llseek         = block_llseek,
2045        .read_iter      = blkdev_read_iter,
2046        .write_iter     = blkdev_write_iter,
2047        .mmap           = generic_file_mmap,
2048        .fsync          = blkdev_fsync,
2049        .unlocked_ioctl = block_ioctl,
2050#ifdef CONFIG_COMPAT
2051        .compat_ioctl   = compat_blkdev_ioctl,
2052#endif
2053        .splice_read    = generic_file_splice_read,
2054        .splice_write   = iter_file_splice_write,
2055        .fallocate      = blkdev_fallocate,
2056};
2057
2058int ioctl_by_bdev(struct block_device *bdev, unsigned cmd, unsigned long arg)
2059{
2060        int res;
2061        mm_segment_t old_fs = get_fs();
2062        set_fs(KERNEL_DS);
2063        res = blkdev_ioctl(bdev, 0, cmd, arg);
2064        set_fs(old_fs);
2065        return res;
2066}
2067
2068EXPORT_SYMBOL(ioctl_by_bdev);
2069
2070/**
2071 * lookup_bdev  - lookup a struct block_device by name
2072 * @pathname:   special file representing the block device
2073 *
2074 * Get a reference to the blockdevice at @pathname in the current
2075 * namespace if possible and return it.  Return ERR_PTR(error)
2076 * otherwise.
2077 */
2078struct block_device *lookup_bdev(const char *pathname)
2079{
2080        struct block_device *bdev;
2081        struct inode *inode;
2082        struct path path;
2083        int error;
2084
2085        if (!pathname || !*pathname)
2086                return ERR_PTR(-EINVAL);
2087
2088        error = kern_path(pathname, LOOKUP_FOLLOW, &path);
2089        if (error)
2090                return ERR_PTR(error);
2091
2092        inode = d_backing_inode(path.dentry);
2093        error = -ENOTBLK;
2094        if (!S_ISBLK(inode->i_mode))
2095                goto fail;
2096        error = -EACCES;
2097        if (!may_open_dev(&path))
2098                goto fail;
2099        error = -ENOMEM;
2100        bdev = bd_acquire(inode);
2101        if (!bdev)
2102                goto fail;
2103out:
2104        path_put(&path);
2105        return bdev;
2106fail:
2107        bdev = ERR_PTR(error);
2108        goto out;
2109}
2110EXPORT_SYMBOL(lookup_bdev);
2111
2112int __invalidate_device(struct block_device *bdev, bool kill_dirty)
2113{
2114        struct super_block *sb = get_super(bdev);
2115        int res = 0;
2116
2117        if (sb) {
2118                /*
2119                 * no need to lock the super, get_super holds the
2120                 * read mutex so the filesystem cannot go away
2121                 * under us (->put_super runs with the write lock
2122                 * hold).
2123                 */
2124                shrink_dcache_sb(sb);
2125                res = invalidate_inodes(sb, kill_dirty);
2126                drop_super(sb);
2127        }
2128        invalidate_bdev(bdev);
2129        return res;
2130}
2131EXPORT_SYMBOL(__invalidate_device);
2132
2133void iterate_bdevs(void (*func)(struct block_device *, void *), void *arg)
2134{
2135        struct inode *inode, *old_inode = NULL;
2136
2137        spin_lock(&blockdev_superblock->s_inode_list_lock);
2138        list_for_each_entry(inode, &blockdev_superblock->s_inodes, i_sb_list) {
2139                struct address_space *mapping = inode->i_mapping;
2140                struct block_device *bdev;
2141
2142                spin_lock(&inode->i_lock);
2143                if (inode->i_state & (I_FREEING|I_WILL_FREE|I_NEW) ||
2144                    mapping->nrpages == 0) {
2145                        spin_unlock(&inode->i_lock);
2146                        continue;
2147                }
2148                __iget(inode);
2149                spin_unlock(&inode->i_lock);
2150                spin_unlock(&blockdev_superblock->s_inode_list_lock);
2151                /*
2152                 * We hold a reference to 'inode' so it couldn't have been
2153                 * removed from s_inodes list while we dropped the
2154                 * s_inode_list_lock  We cannot iput the inode now as we can
2155                 * be holding the last reference and we cannot iput it under
2156                 * s_inode_list_lock. So we keep the reference and iput it
2157                 * later.
2158                 */
2159                iput(old_inode);
2160                old_inode = inode;
2161                bdev = I_BDEV(inode);
2162
2163                mutex_lock(&bdev->bd_mutex);
2164                if (bdev->bd_openers)
2165                        func(bdev, arg);
2166                mutex_unlock(&bdev->bd_mutex);
2167
2168                spin_lock(&blockdev_superblock->s_inode_list_lock);
2169        }
2170        spin_unlock(&blockdev_superblock->s_inode_list_lock);
2171        iput(old_inode);
2172}
2173