Version:  2.0.40 2.2.26 2.4.37 3.13 3.14 3.15 3.16 3.17 3.18 3.19 4.0 4.1 4.2 4.3 4.4 4.5 4.6 4.7 4.8 4.9 4.10

Linux/fs/block_dev.c

  1 /*
  2  *  linux/fs/block_dev.c
  3  *
  4  *  Copyright (C) 1991, 1992  Linus Torvalds
  5  *  Copyright (C) 2001  Andrea Arcangeli <andrea@suse.de> SuSE
  6  */
  7 
  8 #include <linux/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/buffer_head.h>
 22 #include <linux/swap.h>
 23 #include <linux/pagevec.h>
 24 #include <linux/writeback.h>
 25 #include <linux/mpage.h>
 26 #include <linux/mount.h>
 27 #include <linux/uio.h>
 28 #include <linux/namei.h>
 29 #include <linux/log2.h>
 30 #include <linux/cleancache.h>
 31 #include <linux/dax.h>
 32 #include <linux/badblocks.h>
 33 #include <linux/task_io_accounting_ops.h>
 34 #include <linux/falloc.h>
 35 #include <linux/uaccess.h>
 36 #include "internal.h"
 37 
 38 struct bdev_inode {
 39         struct block_device bdev;
 40         struct inode vfs_inode;
 41 };
 42 
 43 static const struct address_space_operations def_blk_aops;
 44 
 45 static inline struct bdev_inode *BDEV_I(struct inode *inode)
 46 {
 47         return container_of(inode, struct bdev_inode, vfs_inode);
 48 }
 49 
 50 struct block_device *I_BDEV(struct inode *inode)
 51 {
 52         return &BDEV_I(inode)->bdev;
 53 }
 54 EXPORT_SYMBOL(I_BDEV);
 55 
 56 void __vfs_msg(struct super_block *sb, const char *prefix, const char *fmt, ...)
 57 {
 58         struct va_format vaf;
 59         va_list args;
 60 
 61         va_start(args, fmt);
 62         vaf.fmt = fmt;
 63         vaf.va = &args;
 64         printk_ratelimited("%sVFS (%s): %pV\n", prefix, sb->s_id, &vaf);
 65         va_end(args);
 66 }
 67 
 68 static void bdev_write_inode(struct block_device *bdev)
 69 {
 70         struct inode *inode = bdev->bd_inode;
 71         int ret;
 72 
 73         spin_lock(&inode->i_lock);
 74         while (inode->i_state & I_DIRTY) {
 75                 spin_unlock(&inode->i_lock);
 76                 ret = write_inode_now(inode, true);
 77                 if (ret) {
 78                         char name[BDEVNAME_SIZE];
 79                         pr_warn_ratelimited("VFS: Dirty inode writeback failed "
 80                                             "for block device %s (err=%d).\n",
 81                                             bdevname(bdev, name), ret);
 82                 }
 83                 spin_lock(&inode->i_lock);
 84         }
 85         spin_unlock(&inode->i_lock);
 86 }
 87 
 88 /* Kill _all_ buffers and pagecache , dirty or not.. */
 89 void kill_bdev(struct block_device *bdev)
 90 {
 91         struct address_space *mapping = bdev->bd_inode->i_mapping;
 92 
 93         if (mapping->nrpages == 0 && mapping->nrexceptional == 0)
 94                 return;
 95 
 96         invalidate_bh_lrus();
 97         truncate_inode_pages(mapping, 0);
 98 }       
 99 EXPORT_SYMBOL(kill_bdev);
100 
101 /* Invalidate clean unused buffers and pagecache. */
102 void invalidate_bdev(struct block_device *bdev)
103 {
104         struct address_space *mapping = bdev->bd_inode->i_mapping;
105 
106         if (mapping->nrpages == 0)
107                 return;
108 
109         invalidate_bh_lrus();
110         lru_add_drain_all();    /* make sure all lru add caches are flushed */
111         invalidate_mapping_pages(mapping, 0, -1);
112         /* 99% of the time, we don't need to flush the cleancache on the bdev.
113          * But, for the strange corners, lets be cautious
114          */
115         cleancache_invalidate_inode(mapping);
116 }
117 EXPORT_SYMBOL(invalidate_bdev);
118 
119 int set_blocksize(struct block_device *bdev, int size)
120 {
121         /* Size must be a power of two, and between 512 and PAGE_SIZE */
122         if (size > PAGE_SIZE || size < 512 || !is_power_of_2(size))
123                 return -EINVAL;
124 
125         /* Size cannot be smaller than the size supported by the device */
126         if (size < bdev_logical_block_size(bdev))
127                 return -EINVAL;
128 
129         /* Don't change the size if it is same as current */
130         if (bdev->bd_block_size != size) {
131                 sync_blockdev(bdev);
132                 bdev->bd_block_size = size;
133                 bdev->bd_inode->i_blkbits = blksize_bits(size);
134                 kill_bdev(bdev);
135         }
136         return 0;
137 }
138 
139 EXPORT_SYMBOL(set_blocksize);
140 
141 int sb_set_blocksize(struct super_block *sb, int size)
142 {
143         if (set_blocksize(sb->s_bdev, size))
144                 return 0;
145         /* If we get here, we know size is power of two
146          * and it's value is between 512 and PAGE_SIZE */
147         sb->s_blocksize = size;
148         sb->s_blocksize_bits = blksize_bits(size);
149         return sb->s_blocksize;
150 }
151 
152 EXPORT_SYMBOL(sb_set_blocksize);
153 
154 int sb_min_blocksize(struct super_block *sb, int size)
155 {
156         int minsize = bdev_logical_block_size(sb->s_bdev);
157         if (size < minsize)
158                 size = minsize;
159         return sb_set_blocksize(sb, size);
160 }
161 
162 EXPORT_SYMBOL(sb_min_blocksize);
163 
164 static int
165 blkdev_get_block(struct inode *inode, sector_t iblock,
166                 struct buffer_head *bh, int create)
167 {
168         bh->b_bdev = I_BDEV(inode);
169         bh->b_blocknr = iblock;
170         set_buffer_mapped(bh);
171         return 0;
172 }
173 
174 static struct inode *bdev_file_inode(struct file *file)
175 {
176         return file->f_mapping->host;
177 }
178 
179 static unsigned int dio_bio_write_op(struct kiocb *iocb)
180 {
181         unsigned int op = REQ_OP_WRITE | REQ_SYNC | REQ_IDLE;
182 
183         /* avoid the need for a I/O completion work item */
184         if (iocb->ki_flags & IOCB_DSYNC)
185                 op |= REQ_FUA;
186         return op;
187 }
188 
189 #define DIO_INLINE_BIO_VECS 4
190 
191 static void blkdev_bio_end_io_simple(struct bio *bio)
192 {
193         struct task_struct *waiter = bio->bi_private;
194 
195         WRITE_ONCE(bio->bi_private, NULL);
196         wake_up_process(waiter);
197 }
198 
199 static ssize_t
200 __blkdev_direct_IO_simple(struct kiocb *iocb, struct iov_iter *iter,
201                 int nr_pages)
202 {
203         struct file *file = iocb->ki_filp;
204         struct block_device *bdev = I_BDEV(bdev_file_inode(file));
205         struct bio_vec inline_vecs[DIO_INLINE_BIO_VECS], *vecs, *bvec;
206         loff_t pos = iocb->ki_pos;
207         bool should_dirty = false;
208         struct bio bio;
209         ssize_t ret;
210         blk_qc_t qc;
211         int i;
212 
213         if ((pos | iov_iter_alignment(iter)) &
214             (bdev_logical_block_size(bdev) - 1))
215                 return -EINVAL;
216 
217         if (nr_pages <= DIO_INLINE_BIO_VECS)
218                 vecs = inline_vecs;
219         else {
220                 vecs = kmalloc(nr_pages * sizeof(struct bio_vec), GFP_KERNEL);
221                 if (!vecs)
222                         return -ENOMEM;
223         }
224 
225         bio_init(&bio, vecs, nr_pages);
226         bio.bi_bdev = bdev;
227         bio.bi_iter.bi_sector = pos >> 9;
228         bio.bi_private = current;
229         bio.bi_end_io = blkdev_bio_end_io_simple;
230 
231         ret = bio_iov_iter_get_pages(&bio, iter);
232         if (unlikely(ret))
233                 return ret;
234         ret = bio.bi_iter.bi_size;
235 
236         if (iov_iter_rw(iter) == READ) {
237                 bio.bi_opf = REQ_OP_READ;
238                 if (iter_is_iovec(iter))
239                         should_dirty = true;
240         } else {
241                 bio.bi_opf = dio_bio_write_op(iocb);
242                 task_io_account_write(ret);
243         }
244 
245         qc = submit_bio(&bio);
246         for (;;) {
247                 set_current_state(TASK_UNINTERRUPTIBLE);
248                 if (!READ_ONCE(bio.bi_private))
249                         break;
250                 if (!(iocb->ki_flags & IOCB_HIPRI) ||
251                     !blk_mq_poll(bdev_get_queue(bdev), qc))
252                         io_schedule();
253         }
254         __set_current_state(TASK_RUNNING);
255 
256         bio_for_each_segment_all(bvec, &bio, i) {
257                 if (should_dirty && !PageCompound(bvec->bv_page))
258                         set_page_dirty_lock(bvec->bv_page);
259                 put_page(bvec->bv_page);
260         }
261 
262         if (vecs != inline_vecs)
263                 kfree(vecs);
264 
265         if (unlikely(bio.bi_error))
266                 return bio.bi_error;
267         return ret;
268 }
269 
270 struct blkdev_dio {
271         union {
272                 struct kiocb            *iocb;
273                 struct task_struct      *waiter;
274         };
275         size_t                  size;
276         atomic_t                ref;
277         bool                    multi_bio : 1;
278         bool                    should_dirty : 1;
279         bool                    is_sync : 1;
280         struct bio              bio;
281 };
282 
283 static struct bio_set *blkdev_dio_pool __read_mostly;
284 
285 static void blkdev_bio_end_io(struct bio *bio)
286 {
287         struct blkdev_dio *dio = bio->bi_private;
288         bool should_dirty = dio->should_dirty;
289 
290         if (dio->multi_bio && !atomic_dec_and_test(&dio->ref)) {
291                 if (bio->bi_error && !dio->bio.bi_error)
292                         dio->bio.bi_error = bio->bi_error;
293         } else {
294                 if (!dio->is_sync) {
295                         struct kiocb *iocb = dio->iocb;
296                         ssize_t ret = dio->bio.bi_error;
297 
298                         if (likely(!ret)) {
299                                 ret = dio->size;
300                                 iocb->ki_pos += ret;
301                         }
302 
303                         dio->iocb->ki_complete(iocb, ret, 0);
304                         bio_put(&dio->bio);
305                 } else {
306                         struct task_struct *waiter = dio->waiter;
307 
308                         WRITE_ONCE(dio->waiter, NULL);
309                         wake_up_process(waiter);
310                 }
311         }
312 
313         if (should_dirty) {
314                 bio_check_pages_dirty(bio);
315         } else {
316                 struct bio_vec *bvec;
317                 int i;
318 
319                 bio_for_each_segment_all(bvec, bio, i)
320                         put_page(bvec->bv_page);
321                 bio_put(bio);
322         }
323 }
324 
325 static ssize_t
326 __blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter, int nr_pages)
327 {
328         struct file *file = iocb->ki_filp;
329         struct inode *inode = bdev_file_inode(file);
330         struct block_device *bdev = I_BDEV(inode);
331         struct blk_plug plug;
332         struct blkdev_dio *dio;
333         struct bio *bio;
334         bool is_read = (iov_iter_rw(iter) == READ), is_sync;
335         loff_t pos = iocb->ki_pos;
336         blk_qc_t qc = BLK_QC_T_NONE;
337         int ret;
338 
339         if ((pos | iov_iter_alignment(iter)) &
340             (bdev_logical_block_size(bdev) - 1))
341                 return -EINVAL;
342 
343         bio = bio_alloc_bioset(GFP_KERNEL, nr_pages, blkdev_dio_pool);
344         bio_get(bio); /* extra ref for the completion handler */
345 
346         dio = container_of(bio, struct blkdev_dio, bio);
347         dio->is_sync = is_sync = is_sync_kiocb(iocb);
348         if (dio->is_sync)
349                 dio->waiter = current;
350         else
351                 dio->iocb = iocb;
352 
353         dio->size = 0;
354         dio->multi_bio = false;
355         dio->should_dirty = is_read && (iter->type == ITER_IOVEC);
356 
357         blk_start_plug(&plug);
358         for (;;) {
359                 bio->bi_bdev = bdev;
360                 bio->bi_iter.bi_sector = pos >> 9;
361                 bio->bi_private = dio;
362                 bio->bi_end_io = blkdev_bio_end_io;
363 
364                 ret = bio_iov_iter_get_pages(bio, iter);
365                 if (unlikely(ret)) {
366                         bio->bi_error = ret;
367                         bio_endio(bio);
368                         break;
369                 }
370 
371                 if (is_read) {
372                         bio->bi_opf = REQ_OP_READ;
373                         if (dio->should_dirty)
374                                 bio_set_pages_dirty(bio);
375                 } else {
376                         bio->bi_opf = dio_bio_write_op(iocb);
377                         task_io_account_write(bio->bi_iter.bi_size);
378                 }
379 
380                 dio->size += bio->bi_iter.bi_size;
381                 pos += bio->bi_iter.bi_size;
382 
383                 nr_pages = iov_iter_npages(iter, BIO_MAX_PAGES);
384                 if (!nr_pages) {
385                         qc = submit_bio(bio);
386                         break;
387                 }
388 
389                 if (!dio->multi_bio) {
390                         dio->multi_bio = true;
391                         atomic_set(&dio->ref, 2);
392                 } else {
393                         atomic_inc(&dio->ref);
394                 }
395 
396                 submit_bio(bio);
397                 bio = bio_alloc(GFP_KERNEL, nr_pages);
398         }
399         blk_finish_plug(&plug);
400 
401         if (!is_sync)
402                 return -EIOCBQUEUED;
403 
404         for (;;) {
405                 set_current_state(TASK_UNINTERRUPTIBLE);
406                 if (!READ_ONCE(dio->waiter))
407                         break;
408 
409                 if (!(iocb->ki_flags & IOCB_HIPRI) ||
410                     !blk_mq_poll(bdev_get_queue(bdev), qc))
411                         io_schedule();
412         }
413         __set_current_state(TASK_RUNNING);
414 
415         ret = dio->bio.bi_error;
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         blkdev_dio_pool = bioset_create(4, offsetof(struct blkdev_dio, bio));
440         if (!blkdev_dio_pool)
441                 return -ENOMEM;
442         return 0;
443 }
444 module_init(blkdev_init);
445 
446 int __sync_blockdev(struct block_device *bdev, int wait)
447 {
448         if (!bdev)
449                 return 0;
450         if (!wait)
451                 return filemap_flush(bdev->bd_inode->i_mapping);
452         return filemap_write_and_wait(bdev->bd_inode->i_mapping);
453 }
454 
455 /*
456  * Write out and wait upon all the dirty data associated with a block
457  * device via its mapping.  Does not take the superblock lock.
458  */
459 int sync_blockdev(struct block_device *bdev)
460 {
461         return __sync_blockdev(bdev, 1);
462 }
463 EXPORT_SYMBOL(sync_blockdev);
464 
465 /*
466  * Write out and wait upon all dirty data associated with this
467  * device.   Filesystem data as well as the underlying block
468  * device.  Takes the superblock lock.
469  */
470 int fsync_bdev(struct block_device *bdev)
471 {
472         struct super_block *sb = get_super(bdev);
473         if (sb) {
474                 int res = sync_filesystem(sb);
475                 drop_super(sb);
476                 return res;
477         }
478         return sync_blockdev(bdev);
479 }
480 EXPORT_SYMBOL(fsync_bdev);
481 
482 /**
483  * freeze_bdev  --  lock a filesystem and force it into a consistent state
484  * @bdev:       blockdevice to lock
485  *
486  * If a superblock is found on this device, we take the s_umount semaphore
487  * on it to make sure nobody unmounts until the snapshot creation is done.
488  * The reference counter (bd_fsfreeze_count) guarantees that only the last
489  * unfreeze process can unfreeze the frozen filesystem actually when multiple
490  * freeze requests arrive simultaneously. It counts up in freeze_bdev() and
491  * count down in thaw_bdev(). When it becomes 0, thaw_bdev() will unfreeze
492  * actually.
493  */
494 struct super_block *freeze_bdev(struct block_device *bdev)
495 {
496         struct super_block *sb;
497         int error = 0;
498 
499         mutex_lock(&bdev->bd_fsfreeze_mutex);
500         if (++bdev->bd_fsfreeze_count > 1) {
501                 /*
502                  * We don't even need to grab a reference - the first call
503                  * to freeze_bdev grab an active reference and only the last
504                  * thaw_bdev drops it.
505                  */
506                 sb = get_super(bdev);
507                 if (sb)
508                         drop_super(sb);
509                 mutex_unlock(&bdev->bd_fsfreeze_mutex);
510                 return sb;
511         }
512 
513         sb = get_active_super(bdev);
514         if (!sb)
515                 goto out;
516         if (sb->s_op->freeze_super)
517                 error = sb->s_op->freeze_super(sb);
518         else
519                 error = freeze_super(sb);
520         if (error) {
521                 deactivate_super(sb);
522                 bdev->bd_fsfreeze_count--;
523                 mutex_unlock(&bdev->bd_fsfreeze_mutex);
524                 return ERR_PTR(error);
525         }
526         deactivate_super(sb);
527  out:
528         sync_blockdev(bdev);
529         mutex_unlock(&bdev->bd_fsfreeze_mutex);
530         return sb;      /* thaw_bdev releases s->s_umount */
531 }
532 EXPORT_SYMBOL(freeze_bdev);
533 
534 /**
535  * thaw_bdev  -- unlock filesystem
536  * @bdev:       blockdevice to unlock
537  * @sb:         associated superblock
538  *
539  * Unlocks the filesystem and marks it writeable again after freeze_bdev().
540  */
541 int thaw_bdev(struct block_device *bdev, struct super_block *sb)
542 {
543         int error = -EINVAL;
544 
545         mutex_lock(&bdev->bd_fsfreeze_mutex);
546         if (!bdev->bd_fsfreeze_count)
547                 goto out;
548 
549         error = 0;
550         if (--bdev->bd_fsfreeze_count > 0)
551                 goto out;
552 
553         if (!sb)
554                 goto out;
555 
556         if (sb->s_op->thaw_super)
557                 error = sb->s_op->thaw_super(sb);
558         else
559                 error = thaw_super(sb);
560         if (error)
561                 bdev->bd_fsfreeze_count++;
562 out:
563         mutex_unlock(&bdev->bd_fsfreeze_mutex);
564         return error;
565 }
566 EXPORT_SYMBOL(thaw_bdev);
567 
568 static int blkdev_writepage(struct page *page, struct writeback_control *wbc)
569 {
570         return block_write_full_page(page, blkdev_get_block, wbc);
571 }
572 
573 static int blkdev_readpage(struct file * file, struct page * page)
574 {
575         return block_read_full_page(page, blkdev_get_block);
576 }
577 
578 static int blkdev_readpages(struct file *file, struct address_space *mapping,
579                         struct list_head *pages, unsigned nr_pages)
580 {
581         return mpage_readpages(mapping, pages, nr_pages, blkdev_get_block);
582 }
583 
584 static int blkdev_write_begin(struct file *file, struct address_space *mapping,
585                         loff_t pos, unsigned len, unsigned flags,
586                         struct page **pagep, void **fsdata)
587 {
588         return block_write_begin(mapping, pos, len, flags, pagep,
589                                  blkdev_get_block);
590 }
591 
592 static int blkdev_write_end(struct file *file, struct address_space *mapping,
593                         loff_t pos, unsigned len, unsigned copied,
594                         struct page *page, void *fsdata)
595 {
596         int ret;
597         ret = block_write_end(file, mapping, pos, len, copied, page, fsdata);
598 
599         unlock_page(page);
600         put_page(page);
601 
602         return ret;
603 }
604 
605 /*
606  * private llseek:
607  * for a block special file file_inode(file)->i_size is zero
608  * so we compute the size by hand (just as in block_read/write above)
609  */
610 static loff_t block_llseek(struct file *file, loff_t offset, int whence)
611 {
612         struct inode *bd_inode = bdev_file_inode(file);
613         loff_t retval;
614 
615         inode_lock(bd_inode);
616         retval = fixed_size_llseek(file, offset, whence, i_size_read(bd_inode));
617         inode_unlock(bd_inode);
618         return retval;
619 }
620         
621 int blkdev_fsync(struct file *filp, loff_t start, loff_t end, int datasync)
622 {
623         struct inode *bd_inode = bdev_file_inode(filp);
624         struct block_device *bdev = I_BDEV(bd_inode);
625         int error;
626         
627         error = filemap_write_and_wait_range(filp->f_mapping, start, end);
628         if (error)
629                 return error;
630 
631         /*
632          * There is no need to serialise calls to blkdev_issue_flush with
633          * i_mutex and doing so causes performance issues with concurrent
634          * O_SYNC writers to a block device.
635          */
636         error = blkdev_issue_flush(bdev, GFP_KERNEL, NULL);
637         if (error == -EOPNOTSUPP)
638                 error = 0;
639 
640         return error;
641 }
642 EXPORT_SYMBOL(blkdev_fsync);
643 
644 /**
645  * bdev_read_page() - Start reading a page from a block device
646  * @bdev: The device to read the page from
647  * @sector: The offset on the device to read the page to (need not be aligned)
648  * @page: The page to read
649  *
650  * On entry, the page should be locked.  It will be unlocked when the page
651  * has been read.  If the block driver implements rw_page synchronously,
652  * that will be true on exit from this function, but it need not be.
653  *
654  * Errors returned by this function are usually "soft", eg out of memory, or
655  * queue full; callers should try a different route to read this page rather
656  * than propagate an error back up the stack.
657  *
658  * Return: negative errno if an error occurs, 0 if submission was successful.
659  */
660 int bdev_read_page(struct block_device *bdev, sector_t sector,
661                         struct page *page)
662 {
663         const struct block_device_operations *ops = bdev->bd_disk->fops;
664         int result = -EOPNOTSUPP;
665 
666         if (!ops->rw_page || bdev_get_integrity(bdev))
667                 return result;
668 
669         result = blk_queue_enter(bdev->bd_queue, false);
670         if (result)
671                 return result;
672         result = ops->rw_page(bdev, sector + get_start_sect(bdev), page, false);
673         blk_queue_exit(bdev->bd_queue);
674         return result;
675 }
676 EXPORT_SYMBOL_GPL(bdev_read_page);
677 
678 /**
679  * bdev_write_page() - Start writing a page to a block device
680  * @bdev: The device to write the page to
681  * @sector: The offset on the device to write the page to (need not be aligned)
682  * @page: The page to write
683  * @wbc: The writeback_control for the write
684  *
685  * On entry, the page should be locked and not currently under writeback.
686  * On exit, if the write started successfully, the page will be unlocked and
687  * under writeback.  If the write failed already (eg the driver failed to
688  * queue the page to the device), the page will still be locked.  If the
689  * caller is a ->writepage implementation, it will need to unlock the page.
690  *
691  * Errors returned by this function are usually "soft", eg out of memory, or
692  * queue full; callers should try a different route to write this page rather
693  * than propagate an error back up the stack.
694  *
695  * Return: negative errno if an error occurs, 0 if submission was successful.
696  */
697 int bdev_write_page(struct block_device *bdev, sector_t sector,
698                         struct page *page, struct writeback_control *wbc)
699 {
700         int result;
701         const struct block_device_operations *ops = bdev->bd_disk->fops;
702 
703         if (!ops->rw_page || bdev_get_integrity(bdev))
704                 return -EOPNOTSUPP;
705         result = blk_queue_enter(bdev->bd_queue, false);
706         if (result)
707                 return result;
708 
709         set_page_writeback(page);
710         result = ops->rw_page(bdev, sector + get_start_sect(bdev), page, true);
711         if (result)
712                 end_page_writeback(page);
713         else
714                 unlock_page(page);
715         blk_queue_exit(bdev->bd_queue);
716         return result;
717 }
718 EXPORT_SYMBOL_GPL(bdev_write_page);
719 
720 /**
721  * bdev_direct_access() - Get the address for directly-accessibly memory
722  * @bdev: The device containing the memory
723  * @dax: control and output parameters for ->direct_access
724  *
725  * If a block device is made up of directly addressable memory, this function
726  * will tell the caller the PFN and the address of the memory.  The address
727  * may be directly dereferenced within the kernel without the need to call
728  * ioremap(), kmap() or similar.  The PFN is suitable for inserting into
729  * page tables.
730  *
731  * Return: negative errno if an error occurs, otherwise the number of bytes
732  * accessible at this address.
733  */
734 long bdev_direct_access(struct block_device *bdev, struct blk_dax_ctl *dax)
735 {
736         sector_t sector = dax->sector;
737         long avail, size = dax->size;
738         const struct block_device_operations *ops = bdev->bd_disk->fops;
739 
740         /*
741          * The device driver is allowed to sleep, in order to make the
742          * memory directly accessible.
743          */
744         might_sleep();
745 
746         if (size < 0)
747                 return size;
748         if (!blk_queue_dax(bdev_get_queue(bdev)) || !ops->direct_access)
749                 return -EOPNOTSUPP;
750         if ((sector + DIV_ROUND_UP(size, 512)) >
751                                         part_nr_sects_read(bdev->bd_part))
752                 return -ERANGE;
753         sector += get_start_sect(bdev);
754         if (sector % (PAGE_SIZE / 512))
755                 return -EINVAL;
756         avail = ops->direct_access(bdev, sector, &dax->addr, &dax->pfn, size);
757         if (!avail)
758                 return -ERANGE;
759         if (avail > 0 && avail & ~PAGE_MASK)
760                 return -ENXIO;
761         return min(avail, size);
762 }
763 EXPORT_SYMBOL_GPL(bdev_direct_access);
764 
765 /**
766  * bdev_dax_supported() - Check if the device supports dax for filesystem
767  * @sb: The superblock of the device
768  * @blocksize: The block size of the device
769  *
770  * This is a library function for filesystems to check if the block device
771  * can be mounted with dax option.
772  *
773  * Return: negative errno if unsupported, 0 if supported.
774  */
775 int bdev_dax_supported(struct super_block *sb, int blocksize)
776 {
777         struct blk_dax_ctl dax = {
778                 .sector = 0,
779                 .size = PAGE_SIZE,
780         };
781         int err;
782 
783         if (blocksize != PAGE_SIZE) {
784                 vfs_msg(sb, KERN_ERR, "error: unsupported blocksize for dax");
785                 return -EINVAL;
786         }
787 
788         err = bdev_direct_access(sb->s_bdev, &dax);
789         if (err < 0) {
790                 switch (err) {
791                 case -EOPNOTSUPP:
792                         vfs_msg(sb, KERN_ERR,
793                                 "error: device does not support dax");
794                         break;
795                 case -EINVAL:
796                         vfs_msg(sb, KERN_ERR,
797                                 "error: unaligned partition for dax");
798                         break;
799                 default:
800                         vfs_msg(sb, KERN_ERR,
801                                 "error: dax access failed (%d)", err);
802                 }
803                 return err;
804         }
805 
806         return 0;
807 }
808 EXPORT_SYMBOL_GPL(bdev_dax_supported);
809 
810 /**
811  * bdev_dax_capable() - Return if the raw device is capable for dax
812  * @bdev: The device for raw block device access
813  */
814 bool bdev_dax_capable(struct block_device *bdev)
815 {
816         struct blk_dax_ctl dax = {
817                 .size = PAGE_SIZE,
818         };
819 
820         if (!IS_ENABLED(CONFIG_FS_DAX))
821                 return false;
822 
823         dax.sector = 0;
824         if (bdev_direct_access(bdev, &dax) < 0)
825                 return false;
826 
827         dax.sector = bdev->bd_part->nr_sects - (PAGE_SIZE / 512);
828         if (bdev_direct_access(bdev, &dax) < 0)
829                 return false;
830 
831         return true;
832 }
833 
834 /*
835  * pseudo-fs
836  */
837 
838 static  __cacheline_aligned_in_smp DEFINE_SPINLOCK(bdev_lock);
839 static struct kmem_cache * bdev_cachep __read_mostly;
840 
841 static struct inode *bdev_alloc_inode(struct super_block *sb)
842 {
843         struct bdev_inode *ei = kmem_cache_alloc(bdev_cachep, GFP_KERNEL);
844         if (!ei)
845                 return NULL;
846         return &ei->vfs_inode;
847 }
848 
849 static void bdev_i_callback(struct rcu_head *head)
850 {
851         struct inode *inode = container_of(head, struct inode, i_rcu);
852         struct bdev_inode *bdi = BDEV_I(inode);
853 
854         kmem_cache_free(bdev_cachep, bdi);
855 }
856 
857 static void bdev_destroy_inode(struct inode *inode)
858 {
859         call_rcu(&inode->i_rcu, bdev_i_callback);
860 }
861 
862 static void init_once(void *foo)
863 {
864         struct bdev_inode *ei = (struct bdev_inode *) foo;
865         struct block_device *bdev = &ei->bdev;
866 
867         memset(bdev, 0, sizeof(*bdev));
868         mutex_init(&bdev->bd_mutex);
869         INIT_LIST_HEAD(&bdev->bd_list);
870 #ifdef CONFIG_SYSFS
871         INIT_LIST_HEAD(&bdev->bd_holder_disks);
872 #endif
873         inode_init_once(&ei->vfs_inode);
874         /* Initialize mutex for freeze. */
875         mutex_init(&bdev->bd_fsfreeze_mutex);
876 }
877 
878 static void bdev_evict_inode(struct inode *inode)
879 {
880         struct block_device *bdev = &BDEV_I(inode)->bdev;
881         truncate_inode_pages_final(&inode->i_data);
882         invalidate_inode_buffers(inode); /* is it needed here? */
883         clear_inode(inode);
884         spin_lock(&bdev_lock);
885         list_del_init(&bdev->bd_list);
886         spin_unlock(&bdev_lock);
887 }
888 
889 static const struct super_operations bdev_sops = {
890         .statfs = simple_statfs,
891         .alloc_inode = bdev_alloc_inode,
892         .destroy_inode = bdev_destroy_inode,
893         .drop_inode = generic_delete_inode,
894         .evict_inode = bdev_evict_inode,
895 };
896 
897 static struct dentry *bd_mount(struct file_system_type *fs_type,
898         int flags, const char *dev_name, void *data)
899 {
900         struct dentry *dent;
901         dent = mount_pseudo(fs_type, "bdev:", &bdev_sops, NULL, BDEVFS_MAGIC);
902         if (!IS_ERR(dent))
903                 dent->d_sb->s_iflags |= SB_I_CGROUPWB;
904         return dent;
905 }
906 
907 static struct file_system_type bd_type = {
908         .name           = "bdev",
909         .mount          = bd_mount,
910         .kill_sb        = kill_anon_super,
911 };
912 
913 struct super_block *blockdev_superblock __read_mostly;
914 EXPORT_SYMBOL_GPL(blockdev_superblock);
915 
916 void __init bdev_cache_init(void)
917 {
918         int err;
919         static struct vfsmount *bd_mnt;
920 
921         bdev_cachep = kmem_cache_create("bdev_cache", sizeof(struct bdev_inode),
922                         0, (SLAB_HWCACHE_ALIGN|SLAB_RECLAIM_ACCOUNT|
923                                 SLAB_MEM_SPREAD|SLAB_ACCOUNT|SLAB_PANIC),
924                         init_once);
925         err = register_filesystem(&bd_type);
926         if (err)
927                 panic("Cannot register bdev pseudo-fs");
928         bd_mnt = kern_mount(&bd_type);
929         if (IS_ERR(bd_mnt))
930                 panic("Cannot create bdev pseudo-fs");
931         blockdev_superblock = bd_mnt->mnt_sb;   /* For writeback */
932 }
933 
934 /*
935  * Most likely _very_ bad one - but then it's hardly critical for small
936  * /dev and can be fixed when somebody will need really large one.
937  * Keep in mind that it will be fed through icache hash function too.
938  */
939 static inline unsigned long hash(dev_t dev)
940 {
941         return MAJOR(dev)+MINOR(dev);
942 }
943 
944 static int bdev_test(struct inode *inode, void *data)
945 {
946         return BDEV_I(inode)->bdev.bd_dev == *(dev_t *)data;
947 }
948 
949 static int bdev_set(struct inode *inode, void *data)
950 {
951         BDEV_I(inode)->bdev.bd_dev = *(dev_t *)data;
952         return 0;
953 }
954 
955 static LIST_HEAD(all_bdevs);
956 
957 struct block_device *bdget(dev_t dev)
958 {
959         struct block_device *bdev;
960         struct inode *inode;
961 
962         inode = iget5_locked(blockdev_superblock, hash(dev),
963                         bdev_test, bdev_set, &dev);
964 
965         if (!inode)
966                 return NULL;
967 
968         bdev = &BDEV_I(inode)->bdev;
969 
970         if (inode->i_state & I_NEW) {
971                 bdev->bd_contains = NULL;
972                 bdev->bd_super = NULL;
973                 bdev->bd_inode = inode;
974                 bdev->bd_block_size = (1 << inode->i_blkbits);
975                 bdev->bd_part_count = 0;
976                 bdev->bd_invalidated = 0;
977                 inode->i_mode = S_IFBLK;
978                 inode->i_rdev = dev;
979                 inode->i_bdev = bdev;
980                 inode->i_data.a_ops = &def_blk_aops;
981                 mapping_set_gfp_mask(&inode->i_data, GFP_USER);
982                 spin_lock(&bdev_lock);
983                 list_add(&bdev->bd_list, &all_bdevs);
984                 spin_unlock(&bdev_lock);
985                 unlock_new_inode(inode);
986         }
987         return bdev;
988 }
989 
990 EXPORT_SYMBOL(bdget);
991 
992 /**
993  * bdgrab -- Grab a reference to an already referenced block device
994  * @bdev:       Block device to grab a reference to.
995  */
996 struct block_device *bdgrab(struct block_device *bdev)
997 {
998         ihold(bdev->bd_inode);
999         return bdev;
1000 }
1001 EXPORT_SYMBOL(bdgrab);
1002 
1003 long nr_blockdev_pages(void)
1004 {
1005         struct block_device *bdev;
1006         long ret = 0;
1007         spin_lock(&bdev_lock);
1008         list_for_each_entry(bdev, &all_bdevs, bd_list) {
1009                 ret += bdev->bd_inode->i_mapping->nrpages;
1010         }
1011         spin_unlock(&bdev_lock);
1012         return ret;
1013 }
1014 
1015 void bdput(struct block_device *bdev)
1016 {
1017         iput(bdev->bd_inode);
1018 }
1019 
1020 EXPORT_SYMBOL(bdput);
1021  
1022 static struct block_device *bd_acquire(struct inode *inode)
1023 {
1024         struct block_device *bdev;
1025 
1026         spin_lock(&bdev_lock);
1027         bdev = inode->i_bdev;
1028         if (bdev) {
1029                 bdgrab(bdev);
1030                 spin_unlock(&bdev_lock);
1031                 return bdev;
1032         }
1033         spin_unlock(&bdev_lock);
1034 
1035         bdev = bdget(inode->i_rdev);
1036         if (bdev) {
1037                 spin_lock(&bdev_lock);
1038                 if (!inode->i_bdev) {
1039                         /*
1040                          * We take an additional reference to bd_inode,
1041                          * and it's released in clear_inode() of inode.
1042                          * So, we can access it via ->i_mapping always
1043                          * without igrab().
1044                          */
1045                         bdgrab(bdev);
1046                         inode->i_bdev = bdev;
1047                         inode->i_mapping = bdev->bd_inode->i_mapping;
1048                 }
1049                 spin_unlock(&bdev_lock);
1050         }
1051         return bdev;
1052 }
1053 
1054 /* Call when you free inode */
1055 
1056 void bd_forget(struct inode *inode)
1057 {
1058         struct block_device *bdev = NULL;
1059 
1060         spin_lock(&bdev_lock);
1061         if (!sb_is_blkdev_sb(inode->i_sb))
1062                 bdev = inode->i_bdev;
1063         inode->i_bdev = NULL;
1064         inode->i_mapping = &inode->i_data;
1065         spin_unlock(&bdev_lock);
1066 
1067         if (bdev)
1068                 bdput(bdev);
1069 }
1070 
1071 /**
1072  * bd_may_claim - test whether a block device can be claimed
1073  * @bdev: block device of interest
1074  * @whole: whole block device containing @bdev, may equal @bdev
1075  * @holder: holder trying to claim @bdev
1076  *
1077  * Test whether @bdev can be claimed by @holder.
1078  *
1079  * CONTEXT:
1080  * spin_lock(&bdev_lock).
1081  *
1082  * RETURNS:
1083  * %true if @bdev can be claimed, %false otherwise.
1084  */
1085 static bool bd_may_claim(struct block_device *bdev, struct block_device *whole,
1086                          void *holder)
1087 {
1088         if (bdev->bd_holder == holder)
1089                 return true;     /* already a holder */
1090         else if (bdev->bd_holder != NULL)
1091                 return false;    /* held by someone else */
1092         else if (whole == bdev)
1093                 return true;     /* is a whole device which isn't held */
1094 
1095         else if (whole->bd_holder == bd_may_claim)
1096                 return true;     /* is a partition of a device that is being partitioned */
1097         else if (whole->bd_holder != NULL)
1098                 return false;    /* is a partition of a held device */
1099         else
1100                 return true;     /* is a partition of an un-held device */
1101 }
1102 
1103 /**
1104  * bd_prepare_to_claim - prepare to claim a block device
1105  * @bdev: block device of interest
1106  * @whole: the whole device containing @bdev, may equal @bdev
1107  * @holder: holder trying to claim @bdev
1108  *
1109  * Prepare to claim @bdev.  This function fails if @bdev is already
1110  * claimed by another holder and waits if another claiming is in
1111  * progress.  This function doesn't actually claim.  On successful
1112  * return, the caller has ownership of bd_claiming and bd_holder[s].
1113  *
1114  * CONTEXT:
1115  * spin_lock(&bdev_lock).  Might release bdev_lock, sleep and regrab
1116  * it multiple times.
1117  *
1118  * RETURNS:
1119  * 0 if @bdev can be claimed, -EBUSY otherwise.
1120  */
1121 static int bd_prepare_to_claim(struct block_device *bdev,
1122                                struct block_device *whole, void *holder)
1123 {
1124 retry:
1125         /* if someone else claimed, fail */
1126         if (!bd_may_claim(bdev, whole, holder))
1127                 return -EBUSY;
1128 
1129         /* if claiming is already in progress, wait for it to finish */
1130         if (whole->bd_claiming) {
1131                 wait_queue_head_t *wq = bit_waitqueue(&whole->bd_claiming, 0);
1132                 DEFINE_WAIT(wait);
1133 
1134                 prepare_to_wait(wq, &wait, TASK_UNINTERRUPTIBLE);
1135                 spin_unlock(&bdev_lock);
1136                 schedule();
1137                 finish_wait(wq, &wait);
1138                 spin_lock(&bdev_lock);
1139                 goto retry;
1140         }
1141 
1142         /* yay, all mine */
1143         return 0;
1144 }
1145 
1146 /**
1147  * bd_start_claiming - start claiming a block device
1148  * @bdev: block device of interest
1149  * @holder: holder trying to claim @bdev
1150  *
1151  * @bdev is about to be opened exclusively.  Check @bdev can be opened
1152  * exclusively and mark that an exclusive open is in progress.  Each
1153  * successful call to this function must be matched with a call to
1154  * either bd_finish_claiming() or bd_abort_claiming() (which do not
1155  * fail).
1156  *
1157  * This function is used to gain exclusive access to the block device
1158  * without actually causing other exclusive open attempts to fail. It
1159  * should be used when the open sequence itself requires exclusive
1160  * access but may subsequently fail.
1161  *
1162  * CONTEXT:
1163  * Might sleep.
1164  *
1165  * RETURNS:
1166  * Pointer to the block device containing @bdev on success, ERR_PTR()
1167  * value on failure.
1168  */
1169 static struct block_device *bd_start_claiming(struct block_device *bdev,
1170                                               void *holder)
1171 {
1172         struct gendisk *disk;
1173         struct block_device *whole;
1174         int partno, err;
1175 
1176         might_sleep();
1177 
1178         /*
1179          * @bdev might not have been initialized properly yet, look up
1180          * and grab the outer block device the hard way.
1181          */
1182         disk = get_gendisk(bdev->bd_dev, &partno);
1183         if (!disk)
1184                 return ERR_PTR(-ENXIO);
1185 
1186         /*
1187          * Normally, @bdev should equal what's returned from bdget_disk()
1188          * if partno is 0; however, some drivers (floppy) use multiple
1189          * bdev's for the same physical device and @bdev may be one of the
1190          * aliases.  Keep @bdev if partno is 0.  This means claimer
1191          * tracking is broken for those devices but it has always been that
1192          * way.
1193          */
1194         if (partno)
1195                 whole = bdget_disk(disk, 0);
1196         else
1197                 whole = bdgrab(bdev);
1198 
1199         module_put(disk->fops->owner);
1200         put_disk(disk);
1201         if (!whole)
1202                 return ERR_PTR(-ENOMEM);
1203 
1204         /* prepare to claim, if successful, mark claiming in progress */
1205         spin_lock(&bdev_lock);
1206 
1207         err = bd_prepare_to_claim(bdev, whole, holder);
1208         if (err == 0) {
1209                 whole->bd_claiming = holder;
1210                 spin_unlock(&bdev_lock);
1211                 return whole;
1212         } else {
1213                 spin_unlock(&bdev_lock);
1214                 bdput(whole);
1215                 return ERR_PTR(err);
1216         }
1217 }
1218 
1219 #ifdef CONFIG_SYSFS
1220 struct bd_holder_disk {
1221         struct list_head        list;
1222         struct gendisk          *disk;
1223         int                     refcnt;
1224 };
1225 
1226 static struct bd_holder_disk *bd_find_holder_disk(struct block_device *bdev,
1227                                                   struct gendisk *disk)
1228 {
1229         struct bd_holder_disk *holder;
1230 
1231         list_for_each_entry(holder, &bdev->bd_holder_disks, list)
1232                 if (holder->disk == disk)
1233                         return holder;
1234         return NULL;
1235 }
1236 
1237 static int add_symlink(struct kobject *from, struct kobject *to)
1238 {
1239         return sysfs_create_link(from, to, kobject_name(to));
1240 }
1241 
1242 static void del_symlink(struct kobject *from, struct kobject *to)
1243 {
1244         sysfs_remove_link(from, kobject_name(to));
1245 }
1246 
1247 /**
1248  * bd_link_disk_holder - create symlinks between holding disk and slave bdev
1249  * @bdev: the claimed slave bdev
1250  * @disk: the holding disk
1251  *
1252  * DON'T USE THIS UNLESS YOU'RE ALREADY USING IT.
1253  *
1254  * This functions creates the following sysfs symlinks.
1255  *
1256  * - from "slaves" directory of the holder @disk to the claimed @bdev
1257  * - from "holders" directory of the @bdev to the holder @disk
1258  *
1259  * For example, if /dev/dm-0 maps to /dev/sda and disk for dm-0 is
1260  * passed to bd_link_disk_holder(), then:
1261  *
1262  *   /sys/block/dm-0/slaves/sda --> /sys/block/sda
1263  *   /sys/block/sda/holders/dm-0 --> /sys/block/dm-0
1264  *
1265  * The caller must have claimed @bdev before calling this function and
1266  * ensure that both @bdev and @disk are valid during the creation and
1267  * lifetime of these symlinks.
1268  *
1269  * CONTEXT:
1270  * Might sleep.
1271  *
1272  * RETURNS:
1273  * 0 on success, -errno on failure.
1274  */
1275 int bd_link_disk_holder(struct block_device *bdev, struct gendisk *disk)
1276 {
1277         struct bd_holder_disk *holder;
1278         int ret = 0;
1279 
1280         mutex_lock(&bdev->bd_mutex);
1281 
1282         WARN_ON_ONCE(!bdev->bd_holder);
1283 
1284         /* FIXME: remove the following once add_disk() handles errors */
1285         if (WARN_ON(!disk->slave_dir || !bdev->bd_part->holder_dir))
1286                 goto out_unlock;
1287 
1288         holder = bd_find_holder_disk(bdev, disk);
1289         if (holder) {
1290                 holder->refcnt++;
1291                 goto out_unlock;
1292         }
1293 
1294         holder = kzalloc(sizeof(*holder), GFP_KERNEL);
1295         if (!holder) {
1296                 ret = -ENOMEM;
1297                 goto out_unlock;
1298         }
1299 
1300         INIT_LIST_HEAD(&holder->list);
1301         holder->disk = disk;
1302         holder->refcnt = 1;
1303 
1304         ret = add_symlink(disk->slave_dir, &part_to_dev(bdev->bd_part)->kobj);
1305         if (ret)
1306                 goto out_free;
1307 
1308         ret = add_symlink(bdev->bd_part->holder_dir, &disk_to_dev(disk)->kobj);
1309         if (ret)
1310                 goto out_del;
1311         /*
1312          * bdev could be deleted beneath us which would implicitly destroy
1313          * the holder directory.  Hold on to it.
1314          */
1315         kobject_get(bdev->bd_part->holder_dir);
1316 
1317         list_add(&holder->list, &bdev->bd_holder_disks);
1318         goto out_unlock;
1319 
1320 out_del:
1321         del_symlink(disk->slave_dir, &part_to_dev(bdev->bd_part)->kobj);
1322 out_free:
1323         kfree(holder);
1324 out_unlock:
1325         mutex_unlock(&bdev->bd_mutex);
1326         return ret;
1327 }
1328 EXPORT_SYMBOL_GPL(bd_link_disk_holder);
1329 
1330 /**
1331  * bd_unlink_disk_holder - destroy symlinks created by bd_link_disk_holder()
1332  * @bdev: the calimed slave bdev
1333  * @disk: the holding disk
1334  *
1335  * DON'T USE THIS UNLESS YOU'RE ALREADY USING IT.
1336  *
1337  * CONTEXT:
1338  * Might sleep.
1339  */
1340 void bd_unlink_disk_holder(struct block_device *bdev, struct gendisk *disk)
1341 {
1342         struct bd_holder_disk *holder;
1343 
1344         mutex_lock(&bdev->bd_mutex);
1345 
1346         holder = bd_find_holder_disk(bdev, disk);
1347 
1348         if (!WARN_ON_ONCE(holder == NULL) && !--holder->refcnt) {
1349                 del_symlink(disk->slave_dir, &part_to_dev(bdev->bd_part)->kobj);
1350                 del_symlink(bdev->bd_part->holder_dir,
1351                             &disk_to_dev(disk)->kobj);
1352                 kobject_put(bdev->bd_part->holder_dir);
1353                 list_del_init(&holder->list);
1354                 kfree(holder);
1355         }
1356 
1357         mutex_unlock(&bdev->bd_mutex);
1358 }
1359 EXPORT_SYMBOL_GPL(bd_unlink_disk_holder);
1360 #endif
1361 
1362 /**
1363  * flush_disk - invalidates all buffer-cache entries on a disk
1364  *
1365  * @bdev:      struct block device to be flushed
1366  * @kill_dirty: flag to guide handling of dirty inodes
1367  *
1368  * Invalidates all buffer-cache entries on a disk. It should be called
1369  * when a disk has been changed -- either by a media change or online
1370  * resize.
1371  */
1372 static void flush_disk(struct block_device *bdev, bool kill_dirty)
1373 {
1374         if (__invalidate_device(bdev, kill_dirty)) {
1375                 printk(KERN_WARNING "VFS: busy inodes on changed media or "
1376                        "resized disk %s\n",
1377                        bdev->bd_disk ? bdev->bd_disk->disk_name : "");
1378         }
1379 
1380         if (!bdev->bd_disk)
1381                 return;
1382         if (disk_part_scan_enabled(bdev->bd_disk))
1383                 bdev->bd_invalidated = 1;
1384 }
1385 
1386 /**
1387  * check_disk_size_change - checks for disk size change and adjusts bdev size.
1388  * @disk: struct gendisk to check
1389  * @bdev: struct bdev to adjust.
1390  *
1391  * This routine checks to see if the bdev size does not match the disk size
1392  * and adjusts it if it differs.
1393  */
1394 void check_disk_size_change(struct gendisk *disk, struct block_device *bdev)
1395 {
1396         loff_t disk_size, bdev_size;
1397 
1398         disk_size = (loff_t)get_capacity(disk) << 9;
1399         bdev_size = i_size_read(bdev->bd_inode);
1400         if (disk_size != bdev_size) {
1401                 printk(KERN_INFO
1402                        "%s: detected capacity change from %lld to %lld\n",
1403                        disk->disk_name, bdev_size, disk_size);
1404                 i_size_write(bdev->bd_inode, disk_size);
1405                 flush_disk(bdev, false);
1406         }
1407 }
1408 EXPORT_SYMBOL(check_disk_size_change);
1409 
1410 /**
1411  * revalidate_disk - wrapper for lower-level driver's revalidate_disk call-back
1412  * @disk: struct gendisk to be revalidated
1413  *
1414  * This routine is a wrapper for lower-level driver's revalidate_disk
1415  * call-backs.  It is used to do common pre and post operations needed
1416  * for all revalidate_disk operations.
1417  */
1418 int revalidate_disk(struct gendisk *disk)
1419 {
1420         struct block_device *bdev;
1421         int ret = 0;
1422 
1423         if (disk->fops->revalidate_disk)
1424                 ret = disk->fops->revalidate_disk(disk);
1425         blk_integrity_revalidate(disk);
1426         bdev = bdget_disk(disk, 0);
1427         if (!bdev)
1428                 return ret;
1429 
1430         mutex_lock(&bdev->bd_mutex);
1431         check_disk_size_change(disk, bdev);
1432         bdev->bd_invalidated = 0;
1433         mutex_unlock(&bdev->bd_mutex);
1434         bdput(bdev);
1435         return ret;
1436 }
1437 EXPORT_SYMBOL(revalidate_disk);
1438 
1439 /*
1440  * This routine checks whether a removable media has been changed,
1441  * and invalidates all buffer-cache-entries in that case. This
1442  * is a relatively slow routine, so we have to try to minimize using
1443  * it. Thus it is called only upon a 'mount' or 'open'. This
1444  * is the best way of combining speed and utility, I think.
1445  * People changing diskettes in the middle of an operation deserve
1446  * to lose :-)
1447  */
1448 int check_disk_change(struct block_device *bdev)
1449 {
1450         struct gendisk *disk = bdev->bd_disk;
1451         const struct block_device_operations *bdops = disk->fops;
1452         unsigned int events;
1453 
1454         events = disk_clear_events(disk, DISK_EVENT_MEDIA_CHANGE |
1455                                    DISK_EVENT_EJECT_REQUEST);
1456         if (!(events & DISK_EVENT_MEDIA_CHANGE))
1457                 return 0;
1458 
1459         flush_disk(bdev, true);
1460         if (bdops->revalidate_disk)
1461                 bdops->revalidate_disk(bdev->bd_disk);
1462         return 1;
1463 }
1464 
1465 EXPORT_SYMBOL(check_disk_change);
1466 
1467 void bd_set_size(struct block_device *bdev, loff_t size)
1468 {
1469         unsigned bsize = bdev_logical_block_size(bdev);
1470 
1471         inode_lock(bdev->bd_inode);
1472         i_size_write(bdev->bd_inode, size);
1473         inode_unlock(bdev->bd_inode);
1474         while (bsize < PAGE_SIZE) {
1475                 if (size & bsize)
1476                         break;
1477                 bsize <<= 1;
1478         }
1479         bdev->bd_block_size = bsize;
1480         bdev->bd_inode->i_blkbits = blksize_bits(bsize);
1481 }
1482 EXPORT_SYMBOL(bd_set_size);
1483 
1484 static void __blkdev_put(struct block_device *bdev, fmode_t mode, int for_part);
1485 
1486 /*
1487  * bd_mutex locking:
1488  *
1489  *  mutex_lock(part->bd_mutex)
1490  *    mutex_lock_nested(whole->bd_mutex, 1)
1491  */
1492 
1493 static int __blkdev_get(struct block_device *bdev, fmode_t mode, int for_part)
1494 {
1495         struct gendisk *disk;
1496         struct module *owner;
1497         int ret;
1498         int partno;
1499         int perm = 0;
1500 
1501         if (mode & FMODE_READ)
1502                 perm |= MAY_READ;
1503         if (mode & FMODE_WRITE)
1504                 perm |= MAY_WRITE;
1505         /*
1506          * hooks: /n/, see "layering violations".
1507          */
1508         if (!for_part) {
1509                 ret = devcgroup_inode_permission(bdev->bd_inode, perm);
1510                 if (ret != 0) {
1511                         bdput(bdev);
1512                         return ret;
1513                 }
1514         }
1515 
1516  restart:
1517 
1518         ret = -ENXIO;
1519         disk = get_gendisk(bdev->bd_dev, &partno);
1520         if (!disk)
1521                 goto out;
1522         owner = disk->fops->owner;
1523 
1524         disk_block_events(disk);
1525         mutex_lock_nested(&bdev->bd_mutex, for_part);
1526         if (!bdev->bd_openers) {
1527                 bdev->bd_disk = disk;
1528                 bdev->bd_queue = disk->queue;
1529                 bdev->bd_contains = bdev;
1530 
1531                 if (!partno) {
1532                         ret = -ENXIO;
1533                         bdev->bd_part = disk_get_part(disk, partno);
1534                         if (!bdev->bd_part)
1535                                 goto out_clear;
1536 
1537                         ret = 0;
1538                         if (disk->fops->open) {
1539                                 ret = disk->fops->open(bdev, mode);
1540                                 if (ret == -ERESTARTSYS) {
1541                                         /* Lost a race with 'disk' being
1542                                          * deleted, try again.
1543                                          * See md.c
1544                                          */
1545                                         disk_put_part(bdev->bd_part);
1546                                         bdev->bd_part = NULL;
1547                                         bdev->bd_disk = NULL;
1548                                         bdev->bd_queue = NULL;
1549                                         mutex_unlock(&bdev->bd_mutex);
1550                                         disk_unblock_events(disk);
1551                                         put_disk(disk);
1552                                         module_put(owner);
1553                                         goto restart;
1554                                 }
1555                         }
1556 
1557                         if (!ret)
1558                                 bd_set_size(bdev,(loff_t)get_capacity(disk)<<9);
1559 
1560                         /*
1561                          * If the device is invalidated, rescan partition
1562                          * if open succeeded or failed with -ENOMEDIUM.
1563                          * The latter is necessary to prevent ghost
1564                          * partitions on a removed medium.
1565                          */
1566                         if (bdev->bd_invalidated) {
1567                                 if (!ret)
1568                                         rescan_partitions(disk, bdev);
1569                                 else if (ret == -ENOMEDIUM)
1570                                         invalidate_partitions(disk, bdev);
1571                         }
1572 
1573                         if (ret)
1574                                 goto out_clear;
1575                 } else {
1576                         struct block_device *whole;
1577                         whole = bdget_disk(disk, 0);
1578                         ret = -ENOMEM;
1579                         if (!whole)
1580                                 goto out_clear;
1581                         BUG_ON(for_part);
1582                         ret = __blkdev_get(whole, mode, 1);
1583                         if (ret)
1584                                 goto out_clear;
1585                         bdev->bd_contains = whole;
1586                         bdev->bd_part = disk_get_part(disk, partno);
1587                         if (!(disk->flags & GENHD_FL_UP) ||
1588                             !bdev->bd_part || !bdev->bd_part->nr_sects) {
1589                                 ret = -ENXIO;
1590                                 goto out_clear;
1591                         }
1592                         bd_set_size(bdev, (loff_t)bdev->bd_part->nr_sects << 9);
1593                 }
1594         } else {
1595                 if (bdev->bd_contains == bdev) {
1596                         ret = 0;
1597                         if (bdev->bd_disk->fops->open)
1598                                 ret = bdev->bd_disk->fops->open(bdev, mode);
1599                         /* the same as first opener case, read comment there */
1600                         if (bdev->bd_invalidated) {
1601                                 if (!ret)
1602                                         rescan_partitions(bdev->bd_disk, bdev);
1603                                 else if (ret == -ENOMEDIUM)
1604                                         invalidate_partitions(bdev->bd_disk, bdev);
1605                         }
1606                         if (ret)
1607                                 goto out_unlock_bdev;
1608                 }
1609                 /* only one opener holds refs to the module and disk */
1610                 put_disk(disk);
1611                 module_put(owner);
1612         }
1613         bdev->bd_openers++;
1614         if (for_part)
1615                 bdev->bd_part_count++;
1616         mutex_unlock(&bdev->bd_mutex);
1617         disk_unblock_events(disk);
1618         return 0;
1619 
1620  out_clear:
1621         disk_put_part(bdev->bd_part);
1622         bdev->bd_disk = NULL;
1623         bdev->bd_part = NULL;
1624         bdev->bd_queue = NULL;
1625         if (bdev != bdev->bd_contains)
1626                 __blkdev_put(bdev->bd_contains, mode, 1);
1627         bdev->bd_contains = NULL;
1628  out_unlock_bdev:
1629         mutex_unlock(&bdev->bd_mutex);
1630         disk_unblock_events(disk);
1631         put_disk(disk);
1632         module_put(owner);
1633  out:
1634         bdput(bdev);
1635 
1636         return ret;
1637 }
1638 
1639 /**
1640  * blkdev_get - open a block device
1641  * @bdev: block_device to open
1642  * @mode: FMODE_* mask
1643  * @holder: exclusive holder identifier
1644  *
1645  * Open @bdev with @mode.  If @mode includes %FMODE_EXCL, @bdev is
1646  * open with exclusive access.  Specifying %FMODE_EXCL with %NULL
1647  * @holder is invalid.  Exclusive opens may nest for the same @holder.
1648  *
1649  * On success, the reference count of @bdev is unchanged.  On failure,
1650  * @bdev is put.
1651  *
1652  * CONTEXT:
1653  * Might sleep.
1654  *
1655  * RETURNS:
1656  * 0 on success, -errno on failure.
1657  */
1658 int blkdev_get(struct block_device *bdev, fmode_t mode, void *holder)
1659 {
1660         struct block_device *whole = NULL;
1661         int res;
1662 
1663         WARN_ON_ONCE((mode & FMODE_EXCL) && !holder);
1664 
1665         if ((mode & FMODE_EXCL) && holder) {
1666                 whole = bd_start_claiming(bdev, holder);
1667                 if (IS_ERR(whole)) {
1668                         bdput(bdev);
1669                         return PTR_ERR(whole);
1670                 }
1671         }
1672 
1673         res = __blkdev_get(bdev, mode, 0);
1674 
1675         if (whole) {
1676                 struct gendisk *disk = whole->bd_disk;
1677 
1678                 /* finish claiming */
1679                 mutex_lock(&bdev->bd_mutex);
1680                 spin_lock(&bdev_lock);
1681 
1682                 if (!res) {
1683                         BUG_ON(!bd_may_claim(bdev, whole, holder));
1684                         /*
1685                          * Note that for a whole device bd_holders
1686                          * will be incremented twice, and bd_holder
1687                          * will be set to bd_may_claim before being
1688                          * set to holder
1689                          */
1690                         whole->bd_holders++;
1691                         whole->bd_holder = bd_may_claim;
1692                         bdev->bd_holders++;
1693                         bdev->bd_holder = holder;
1694                 }
1695 
1696                 /* tell others that we're done */
1697                 BUG_ON(whole->bd_claiming != holder);
1698                 whole->bd_claiming = NULL;
1699                 wake_up_bit(&whole->bd_claiming, 0);
1700 
1701                 spin_unlock(&bdev_lock);
1702 
1703                 /*
1704                  * Block event polling for write claims if requested.  Any
1705                  * write holder makes the write_holder state stick until
1706                  * all are released.  This is good enough and tracking
1707                  * individual writeable reference is too fragile given the
1708                  * way @mode is used in blkdev_get/put().
1709                  */
1710                 if (!res && (mode & FMODE_WRITE) && !bdev->bd_write_holder &&
1711                     (disk->flags & GENHD_FL_BLOCK_EVENTS_ON_EXCL_WRITE)) {
1712                         bdev->bd_write_holder = true;
1713                         disk_block_events(disk);
1714                 }
1715 
1716                 mutex_unlock(&bdev->bd_mutex);
1717                 bdput(whole);
1718         }
1719 
1720         return res;
1721 }
1722 EXPORT_SYMBOL(blkdev_get);
1723 
1724 /**
1725  * blkdev_get_by_path - open a block device by name
1726  * @path: path to the block device to open
1727  * @mode: FMODE_* mask
1728  * @holder: exclusive holder identifier
1729  *
1730  * Open the blockdevice described by the device file at @path.  @mode
1731  * and @holder are identical to blkdev_get().
1732  *
1733  * On success, the returned block_device has reference count of one.
1734  *
1735  * CONTEXT:
1736  * Might sleep.
1737  *
1738  * RETURNS:
1739  * Pointer to block_device on success, ERR_PTR(-errno) on failure.
1740  */
1741 struct block_device *blkdev_get_by_path(const char *path, fmode_t mode,
1742                                         void *holder)
1743 {
1744         struct block_device *bdev;
1745         int err;
1746 
1747         bdev = lookup_bdev(path);
1748         if (IS_ERR(bdev))
1749                 return bdev;
1750 
1751         err = blkdev_get(bdev, mode, holder);
1752         if (err)
1753                 return ERR_PTR(err);
1754 
1755         if ((mode & FMODE_WRITE) && bdev_read_only(bdev)) {
1756                 blkdev_put(bdev, mode);
1757                 return ERR_PTR(-EACCES);
1758         }
1759 
1760         return bdev;
1761 }
1762 EXPORT_SYMBOL(blkdev_get_by_path);
1763 
1764 /**
1765  * blkdev_get_by_dev - open a block device by device number
1766  * @dev: device number of block device to open
1767  * @mode: FMODE_* mask
1768  * @holder: exclusive holder identifier
1769  *
1770  * Open the blockdevice described by device number @dev.  @mode and
1771  * @holder are identical to blkdev_get().
1772  *
1773  * Use it ONLY if you really do not have anything better - i.e. when
1774  * you are behind a truly sucky interface and all you are given is a
1775  * device number.  _Never_ to be used for internal purposes.  If you
1776  * ever need it - reconsider your API.
1777  *
1778  * On success, the returned block_device has reference count of one.
1779  *
1780  * CONTEXT:
1781  * Might sleep.
1782  *
1783  * RETURNS:
1784  * Pointer to block_device on success, ERR_PTR(-errno) on failure.
1785  */
1786 struct block_device *blkdev_get_by_dev(dev_t dev, fmode_t mode, void *holder)
1787 {
1788         struct block_device *bdev;
1789         int err;
1790 
1791         bdev = bdget(dev);
1792         if (!bdev)
1793                 return ERR_PTR(-ENOMEM);
1794 
1795         err = blkdev_get(bdev, mode, holder);
1796         if (err)
1797                 return ERR_PTR(err);
1798 
1799         return bdev;
1800 }
1801 EXPORT_SYMBOL(blkdev_get_by_dev);
1802 
1803 static int blkdev_open(struct inode * inode, struct file * filp)
1804 {
1805         struct block_device *bdev;
1806 
1807         /*
1808          * Preserve backwards compatibility and allow large file access
1809          * even if userspace doesn't ask for it explicitly. Some mkfs
1810          * binary needs it. We might want to drop this workaround
1811          * during an unstable branch.
1812          */
1813         filp->f_flags |= O_LARGEFILE;
1814 
1815         if (filp->f_flags & O_NDELAY)
1816                 filp->f_mode |= FMODE_NDELAY;
1817         if (filp->f_flags & O_EXCL)
1818                 filp->f_mode |= FMODE_EXCL;
1819         if ((filp->f_flags & O_ACCMODE) == 3)
1820                 filp->f_mode |= FMODE_WRITE_IOCTL;
1821 
1822         bdev = bd_acquire(inode);
1823         if (bdev == NULL)
1824                 return -ENOMEM;
1825 
1826         filp->f_mapping = bdev->bd_inode->i_mapping;
1827 
1828         return blkdev_get(bdev, filp->f_mode, filp);
1829 }
1830 
1831 static void __blkdev_put(struct block_device *bdev, fmode_t mode, int for_part)
1832 {
1833         struct gendisk *disk = bdev->bd_disk;
1834         struct block_device *victim = NULL;
1835 
1836         mutex_lock_nested(&bdev->bd_mutex, for_part);
1837         if (for_part)
1838                 bdev->bd_part_count--;
1839 
1840         if (!--bdev->bd_openers) {
1841                 WARN_ON_ONCE(bdev->bd_holders);
1842                 sync_blockdev(bdev);
1843                 kill_bdev(bdev);
1844 
1845                 bdev_write_inode(bdev);
1846                 /*
1847                  * Detaching bdev inode from its wb in __destroy_inode()
1848                  * is too late: the queue which embeds its bdi (along with
1849                  * root wb) can be gone as soon as we put_disk() below.
1850                  */
1851                 inode_detach_wb(bdev->bd_inode);
1852         }
1853         if (bdev->bd_contains == bdev) {
1854                 if (disk->fops->release)
1855                         disk->fops->release(disk, mode);
1856         }
1857         if (!bdev->bd_openers) {
1858                 struct module *owner = disk->fops->owner;
1859 
1860                 disk_put_part(bdev->bd_part);
1861                 bdev->bd_part = NULL;
1862                 bdev->bd_disk = NULL;
1863                 if (bdev != bdev->bd_contains)
1864                         victim = bdev->bd_contains;
1865                 bdev->bd_contains = NULL;
1866 
1867                 put_disk(disk);
1868                 module_put(owner);
1869         }
1870         mutex_unlock(&bdev->bd_mutex);
1871         bdput(bdev);
1872         if (victim)
1873                 __blkdev_put(victim, mode, 1);
1874 }
1875 
1876 void blkdev_put(struct block_device *bdev, fmode_t mode)
1877 {
1878         mutex_lock(&bdev->bd_mutex);
1879 
1880         if (mode & FMODE_EXCL) {
1881                 bool bdev_free;
1882 
1883                 /*
1884                  * Release a claim on the device.  The holder fields
1885                  * are protected with bdev_lock.  bd_mutex is to
1886                  * synchronize disk_holder unlinking.
1887                  */
1888                 spin_lock(&bdev_lock);
1889 
1890                 WARN_ON_ONCE(--bdev->bd_holders < 0);
1891                 WARN_ON_ONCE(--bdev->bd_contains->bd_holders < 0);
1892 
1893                 /* bd_contains might point to self, check in a separate step */
1894                 if ((bdev_free = !bdev->bd_holders))
1895                         bdev->bd_holder = NULL;
1896                 if (!bdev->bd_contains->bd_holders)
1897                         bdev->bd_contains->bd_holder = NULL;
1898 
1899                 spin_unlock(&bdev_lock);
1900 
1901                 /*
1902                  * If this was the last claim, remove holder link and
1903                  * unblock evpoll if it was a write holder.
1904                  */
1905                 if (bdev_free && bdev->bd_write_holder) {
1906                         disk_unblock_events(bdev->bd_disk);
1907                         bdev->bd_write_holder = false;
1908                 }
1909         }
1910 
1911         /*
1912          * Trigger event checking and tell drivers to flush MEDIA_CHANGE
1913          * event.  This is to ensure detection of media removal commanded
1914          * from userland - e.g. eject(1).
1915          */
1916         disk_flush_events(bdev->bd_disk, DISK_EVENT_MEDIA_CHANGE);
1917 
1918         mutex_unlock(&bdev->bd_mutex);
1919 
1920         __blkdev_put(bdev, mode, 0);
1921 }
1922 EXPORT_SYMBOL(blkdev_put);
1923 
1924 static int blkdev_close(struct inode * inode, struct file * filp)
1925 {
1926         struct block_device *bdev = I_BDEV(bdev_file_inode(filp));
1927         blkdev_put(bdev, filp->f_mode);
1928         return 0;
1929 }
1930 
1931 static long block_ioctl(struct file *file, unsigned cmd, unsigned long arg)
1932 {
1933         struct block_device *bdev = I_BDEV(bdev_file_inode(file));
1934         fmode_t mode = file->f_mode;
1935 
1936         /*
1937          * O_NDELAY can be altered using fcntl(.., F_SETFL, ..), so we have
1938          * to updated it before every ioctl.
1939          */
1940         if (file->f_flags & O_NDELAY)
1941                 mode |= FMODE_NDELAY;
1942         else
1943                 mode &= ~FMODE_NDELAY;
1944 
1945         return blkdev_ioctl(bdev, mode, cmd, arg);
1946 }
1947 
1948 /*
1949  * Write data to the block device.  Only intended for the block device itself
1950  * and the raw driver which basically is a fake block device.
1951  *
1952  * Does not take i_mutex for the write and thus is not for general purpose
1953  * use.
1954  */
1955 ssize_t blkdev_write_iter(struct kiocb *iocb, struct iov_iter *from)
1956 {
1957         struct file *file = iocb->ki_filp;
1958         struct inode *bd_inode = bdev_file_inode(file);
1959         loff_t size = i_size_read(bd_inode);
1960         struct blk_plug plug;
1961         ssize_t ret;
1962 
1963         if (bdev_read_only(I_BDEV(bd_inode)))
1964                 return -EPERM;
1965 
1966         if (!iov_iter_count(from))
1967                 return 0;
1968 
1969         if (iocb->ki_pos >= size)
1970                 return -ENOSPC;
1971 
1972         iov_iter_truncate(from, size - iocb->ki_pos);
1973 
1974         blk_start_plug(&plug);
1975         ret = __generic_file_write_iter(iocb, from);
1976         if (ret > 0)
1977                 ret = generic_write_sync(iocb, ret);
1978         blk_finish_plug(&plug);
1979         return ret;
1980 }
1981 EXPORT_SYMBOL_GPL(blkdev_write_iter);
1982 
1983 ssize_t blkdev_read_iter(struct kiocb *iocb, struct iov_iter *to)
1984 {
1985         struct file *file = iocb->ki_filp;
1986         struct inode *bd_inode = bdev_file_inode(file);
1987         loff_t size = i_size_read(bd_inode);
1988         loff_t pos = iocb->ki_pos;
1989 
1990         if (pos >= size)
1991                 return 0;
1992 
1993         size -= pos;
1994         iov_iter_truncate(to, size);
1995         return generic_file_read_iter(iocb, to);
1996 }
1997 EXPORT_SYMBOL_GPL(blkdev_read_iter);
1998 
1999 /*
2000  * Try to release a page associated with block device when the system
2001  * is under memory pressure.
2002  */
2003 static int blkdev_releasepage(struct page *page, gfp_t wait)
2004 {
2005         struct super_block *super = BDEV_I(page->mapping->host)->bdev.bd_super;
2006 
2007         if (super && super->s_op->bdev_try_to_free_page)
2008                 return super->s_op->bdev_try_to_free_page(super, page, wait);
2009 
2010         return try_to_free_buffers(page);
2011 }
2012 
2013 static int blkdev_writepages(struct address_space *mapping,
2014                              struct writeback_control *wbc)
2015 {
2016         if (dax_mapping(mapping)) {
2017                 struct block_device *bdev = I_BDEV(mapping->host);
2018 
2019                 return dax_writeback_mapping_range(mapping, bdev, wbc);
2020         }
2021         return generic_writepages(mapping, wbc);
2022 }
2023 
2024 static const struct address_space_operations def_blk_aops = {
2025         .readpage       = blkdev_readpage,
2026         .readpages      = blkdev_readpages,
2027         .writepage      = blkdev_writepage,
2028         .write_begin    = blkdev_write_begin,
2029         .write_end      = blkdev_write_end,
2030         .writepages     = blkdev_writepages,
2031         .releasepage    = blkdev_releasepage,
2032         .direct_IO      = blkdev_direct_IO,
2033         .is_dirty_writeback = buffer_check_dirty_writeback,
2034 };
2035 
2036 #define BLKDEV_FALLOC_FL_SUPPORTED                                      \
2037                 (FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE |           \
2038                  FALLOC_FL_ZERO_RANGE | FALLOC_FL_NO_HIDE_STALE)
2039 
2040 static long blkdev_fallocate(struct file *file, int mode, loff_t start,
2041                              loff_t len)
2042 {
2043         struct block_device *bdev = I_BDEV(bdev_file_inode(file));
2044         struct request_queue *q = bdev_get_queue(bdev);
2045         struct address_space *mapping;
2046         loff_t end = start + len - 1;
2047         loff_t isize;
2048         int error;
2049 
2050         /* Fail if we don't recognize the flags. */
2051         if (mode & ~BLKDEV_FALLOC_FL_SUPPORTED)
2052                 return -EOPNOTSUPP;
2053 
2054         /* Don't go off the end of the device. */
2055         isize = i_size_read(bdev->bd_inode);
2056         if (start >= isize)
2057                 return -EINVAL;
2058         if (end >= isize) {
2059                 if (mode & FALLOC_FL_KEEP_SIZE) {
2060                         len = isize - start;
2061                         end = start + len - 1;
2062                 } else
2063                         return -EINVAL;
2064         }
2065 
2066         /*
2067          * Don't allow IO that isn't aligned to logical block size.
2068          */
2069         if ((start | len) & (bdev_logical_block_size(bdev) - 1))
2070                 return -EINVAL;
2071 
2072         /* Invalidate the page cache, including dirty pages. */
2073         mapping = bdev->bd_inode->i_mapping;
2074         truncate_inode_pages_range(mapping, start, end);
2075 
2076         switch (mode) {
2077         case FALLOC_FL_ZERO_RANGE:
2078         case FALLOC_FL_ZERO_RANGE | FALLOC_FL_KEEP_SIZE:
2079                 error = blkdev_issue_zeroout(bdev, start >> 9, len >> 9,
2080                                             GFP_KERNEL, false);
2081                 break;
2082         case FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE:
2083                 /* Only punch if the device can do zeroing discard. */
2084                 if (!blk_queue_discard(q) || !q->limits.discard_zeroes_data)
2085                         return -EOPNOTSUPP;
2086                 error = blkdev_issue_discard(bdev, start >> 9, len >> 9,
2087                                              GFP_KERNEL, 0);
2088                 break;
2089         case FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE | FALLOC_FL_NO_HIDE_STALE:
2090                 if (!blk_queue_discard(q))
2091                         return -EOPNOTSUPP;
2092                 error = blkdev_issue_discard(bdev, start >> 9, len >> 9,
2093                                              GFP_KERNEL, 0);
2094                 break;
2095         default:
2096                 return -EOPNOTSUPP;
2097         }
2098         if (error)
2099                 return error;
2100 
2101         /*
2102          * Invalidate again; if someone wandered in and dirtied a page,
2103          * the caller will be given -EBUSY.  The third argument is
2104          * inclusive, so the rounding here is safe.
2105          */
2106         return invalidate_inode_pages2_range(mapping,
2107                                              start >> PAGE_SHIFT,
2108                                              end >> PAGE_SHIFT);
2109 }
2110 
2111 const struct file_operations def_blk_fops = {
2112         .open           = blkdev_open,
2113         .release        = blkdev_close,
2114         .llseek         = block_llseek,
2115         .read_iter      = blkdev_read_iter,
2116         .write_iter     = blkdev_write_iter,
2117         .mmap           = generic_file_mmap,
2118         .fsync          = blkdev_fsync,
2119         .unlocked_ioctl = block_ioctl,
2120 #ifdef CONFIG_COMPAT
2121         .compat_ioctl   = compat_blkdev_ioctl,
2122 #endif
2123         .splice_read    = generic_file_splice_read,
2124         .splice_write   = iter_file_splice_write,
2125         .fallocate      = blkdev_fallocate,
2126 };
2127 
2128 int ioctl_by_bdev(struct block_device *bdev, unsigned cmd, unsigned long arg)
2129 {
2130         int res;
2131         mm_segment_t old_fs = get_fs();
2132         set_fs(KERNEL_DS);
2133         res = blkdev_ioctl(bdev, 0, cmd, arg);
2134         set_fs(old_fs);
2135         return res;
2136 }
2137 
2138 EXPORT_SYMBOL(ioctl_by_bdev);
2139 
2140 /**
2141  * lookup_bdev  - lookup a struct block_device by name
2142  * @pathname:   special file representing the block device
2143  *
2144  * Get a reference to the blockdevice at @pathname in the current
2145  * namespace if possible and return it.  Return ERR_PTR(error)
2146  * otherwise.
2147  */
2148 struct block_device *lookup_bdev(const char *pathname)
2149 {
2150         struct block_device *bdev;
2151         struct inode *inode;
2152         struct path path;
2153         int error;
2154 
2155         if (!pathname || !*pathname)
2156                 return ERR_PTR(-EINVAL);
2157 
2158         error = kern_path(pathname, LOOKUP_FOLLOW, &path);
2159         if (error)
2160                 return ERR_PTR(error);
2161 
2162         inode = d_backing_inode(path.dentry);
2163         error = -ENOTBLK;
2164         if (!S_ISBLK(inode->i_mode))
2165                 goto fail;
2166         error = -EACCES;
2167         if (!may_open_dev(&path))
2168                 goto fail;
2169         error = -ENOMEM;
2170         bdev = bd_acquire(inode);
2171         if (!bdev)
2172                 goto fail;
2173 out:
2174         path_put(&path);
2175         return bdev;
2176 fail:
2177         bdev = ERR_PTR(error);
2178         goto out;
2179 }
2180 EXPORT_SYMBOL(lookup_bdev);
2181 
2182 int __invalidate_device(struct block_device *bdev, bool kill_dirty)
2183 {
2184         struct super_block *sb = get_super(bdev);
2185         int res = 0;
2186 
2187         if (sb) {
2188                 /*
2189                  * no need to lock the super, get_super holds the
2190                  * read mutex so the filesystem cannot go away
2191                  * under us (->put_super runs with the write lock
2192                  * hold).
2193                  */
2194                 shrink_dcache_sb(sb);
2195                 res = invalidate_inodes(sb, kill_dirty);
2196                 drop_super(sb);
2197         }
2198         invalidate_bdev(bdev);
2199         return res;
2200 }
2201 EXPORT_SYMBOL(__invalidate_device);
2202 
2203 void iterate_bdevs(void (*func)(struct block_device *, void *), void *arg)
2204 {
2205         struct inode *inode, *old_inode = NULL;
2206 
2207         spin_lock(&blockdev_superblock->s_inode_list_lock);
2208         list_for_each_entry(inode, &blockdev_superblock->s_inodes, i_sb_list) {
2209                 struct address_space *mapping = inode->i_mapping;
2210                 struct block_device *bdev;
2211 
2212                 spin_lock(&inode->i_lock);
2213                 if (inode->i_state & (I_FREEING|I_WILL_FREE|I_NEW) ||
2214                     mapping->nrpages == 0) {
2215                         spin_unlock(&inode->i_lock);
2216                         continue;
2217                 }
2218                 __iget(inode);
2219                 spin_unlock(&inode->i_lock);
2220                 spin_unlock(&blockdev_superblock->s_inode_list_lock);
2221                 /*
2222                  * We hold a reference to 'inode' so it couldn't have been
2223                  * removed from s_inodes list while we dropped the
2224                  * s_inode_list_lock  We cannot iput the inode now as we can
2225                  * be holding the last reference and we cannot iput it under
2226                  * s_inode_list_lock. So we keep the reference and iput it
2227                  * later.
2228                  */
2229                 iput(old_inode);
2230                 old_inode = inode;
2231                 bdev = I_BDEV(inode);
2232 
2233                 mutex_lock(&bdev->bd_mutex);
2234                 if (bdev->bd_openers)
2235                         func(bdev, arg);
2236                 mutex_unlock(&bdev->bd_mutex);
2237 
2238                 spin_lock(&blockdev_superblock->s_inode_list_lock);
2239         }
2240         spin_unlock(&blockdev_superblock->s_inode_list_lock);
2241         iput(old_inode);
2242 }
2243 

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