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TOMOYO Linux Cross Reference
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 
 39 struct bdev_inode {
 40         struct block_device bdev;
 41         struct inode vfs_inode;
 42 };
 43 
 44 static const struct address_space_operations def_blk_aops;
 45 
 46 static inline struct bdev_inode *BDEV_I(struct inode *inode)
 47 {
 48         return container_of(inode, struct bdev_inode, vfs_inode);
 49 }
 50 
 51 struct block_device *I_BDEV(struct inode *inode)
 52 {
 53         return &BDEV_I(inode)->bdev;
 54 }
 55 EXPORT_SYMBOL(I_BDEV);
 56 
 57 static 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.. */
 78 void 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 }       
 88 EXPORT_SYMBOL(kill_bdev);
 89 
 90 /* Invalidate clean unused buffers and pagecache. */
 91 void 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 }
105 EXPORT_SYMBOL(invalidate_bdev);
106 
107 int 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 
127 EXPORT_SYMBOL(set_blocksize);
128 
129 int 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 
140 EXPORT_SYMBOL(sb_set_blocksize);
141 
142 int 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 
150 EXPORT_SYMBOL(sb_min_blocksize);
151 
152 static int
153 blkdev_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 
162 static struct inode *bdev_file_inode(struct file *file)
163 {
164         return file->f_mapping->host;
165 }
166 
167 static 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 
179 static 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 
187 static 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 
256 out:
257         if (vecs != inline_vecs)
258                 kfree(vecs);
259 
260         bio_uninit(&bio);
261 
262         return ret;
263 }
264 
265 struct 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 
278 static struct bio_set blkdev_dio_pool;
279 
280 static 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 
322 static 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 
423 static ssize_t
424 blkdev_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 
437 static __init int blkdev_init(void)
438 {
439         return bioset_init(&blkdev_dio_pool, 4, offsetof(struct blkdev_dio, bio), BIOSET_NEED_BVECS);
440 }
441 module_init(blkdev_init);
442 
443 int __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  */
456 int sync_blockdev(struct block_device *bdev)
457 {
458         return __sync_blockdev(bdev, 1);
459 }
460 EXPORT_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  */
467 int 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 }
477 EXPORT_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  */
491 struct 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 }
529 EXPORT_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  */
538 int 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++;
559 out:
560         mutex_unlock(&bdev->bd_fsfreeze_mutex);
561         return error;
562 }
563 EXPORT_SYMBOL(thaw_bdev);
564 
565 static int blkdev_writepage(struct page *page, struct writeback_control *wbc)
566 {
567         return block_write_full_page(page, blkdev_get_block, wbc);
568 }
569 
570 static int blkdev_readpage(struct file * file, struct page * page)
571 {
572         return block_read_full_page(page, blkdev_get_block);
573 }
574 
575 static 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 
581 static 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 
589 static 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  */
607 static 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         
618 int 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 }
639 EXPORT_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  */
657 int 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 }
674 EXPORT_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  */
695 int 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 }
719 EXPORT_SYMBOL_GPL(bdev_write_page);
720 
721 /*
722  * pseudo-fs
723  */
724 
725 static  __cacheline_aligned_in_smp DEFINE_SPINLOCK(bdev_lock);
726 static struct kmem_cache * bdev_cachep __read_mostly;
727 
728 static 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 
736 static 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 
744 static void bdev_destroy_inode(struct inode *inode)
745 {
746         call_rcu(&inode->i_rcu, bdev_i_callback);
747 }
748 
749 static 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 
766 static 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 
783 static 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 
791 static 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 
801 static struct file_system_type bd_type = {
802         .name           = "bdev",
803         .mount          = bd_mount,
804         .kill_sb        = kill_anon_super,
805 };
806 
807 struct super_block *blockdev_superblock __read_mostly;
808 EXPORT_SYMBOL_GPL(blockdev_superblock);
809 
810 void __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  */
833 static inline unsigned long hash(dev_t dev)
834 {
835         return MAJOR(dev)+MINOR(dev);
836 }
837 
838 static int bdev_test(struct inode *inode, void *data)
839 {
840         return BDEV_I(inode)->bdev.bd_dev == *(dev_t *)data;
841 }
842 
843 static int bdev_set(struct inode *inode, void *data)
844 {
845         BDEV_I(inode)->bdev.bd_dev = *(dev_t *)data;
846         return 0;
847 }
848 
849 static 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  */
855 void 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 
866 struct 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 
899 EXPORT_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  */
905 struct block_device *bdgrab(struct block_device *bdev)
906 {
907         ihold(bdev->bd_inode);
908         return bdev;
909 }
910 EXPORT_SYMBOL(bdgrab);
911 
912 long 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 
924 void bdput(struct block_device *bdev)
925 {
926         iput(bdev->bd_inode);
927 }
928 
929 EXPORT_SYMBOL(bdput);
930  
931 static 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 
974 void 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  */
1003 static 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  */
1039 static int bd_prepare_to_claim(struct block_device *bdev,
1040                                struct block_device *whole, void *holder)
1041 {
1042 retry:
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 
1064 static 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  */
1108 static 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
1158 struct bd_holder_disk {
1159         struct list_head        list;
1160         struct gendisk          *disk;
1161         int                     refcnt;
1162 };
1163 
1164 static 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 
1175 static int add_symlink(struct kobject *from, struct kobject *to)
1176 {
1177         return sysfs_create_link(from, to, kobject_name(to));
1178 }
1179 
1180 static 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  */
1213 int 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 
1258 out_del:
1259         del_symlink(disk->slave_dir, &part_to_dev(bdev->bd_part)->kobj);
1260 out_free:
1261         kfree(holder);
1262 out_unlock:
1263         mutex_unlock(&bdev->bd_mutex);
1264         return ret;
1265 }
1266 EXPORT_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  */
1278 void 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 }
1297 EXPORT_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  */
1310 static 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  */
1334 void 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  */
1361 int 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 }
1379 EXPORT_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  */
1390 int 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 
1407 EXPORT_SYMBOL(check_disk_change);
1408 
1409 void 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 }
1424 EXPORT_SYMBOL(bd_set_size);
1425 
1426 static 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 
1435 static 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  */
1602 int 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 }
1666 EXPORT_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  */
1685 struct 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 }
1706 EXPORT_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  */
1730 struct 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 }
1745 EXPORT_SYMBOL(blkdev_get_by_dev);
1746 
1747 static 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 
1778 static 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 
1814 void 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 }
1860 EXPORT_SYMBOL(blkdev_put);
1861 
1862 static 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 
1869 static 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  */
1893 ssize_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 }
1922 EXPORT_SYMBOL_GPL(blkdev_write_iter);
1923 
1924 ssize_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 }
1938 EXPORT_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  */
1944 static 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 
1954 static int blkdev_writepages(struct address_space *mapping,
1955                              struct writeback_control *wbc)
1956 {
1957         return generic_writepages(mapping, wbc);
1958 }
1959 
1960 static 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 
1976 static 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 
2041 const 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 
2058 int 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 
2068 EXPORT_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  */
2078 struct 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;
2103 out:
2104         path_put(&path);
2105         return bdev;
2106 fail:
2107         bdev = ERR_PTR(error);
2108         goto out;
2109 }
2110 EXPORT_SYMBOL(lookup_bdev);
2111 
2112 int __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 }
2131 EXPORT_SYMBOL(__invalidate_device);
2132 
2133 void 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 

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