4 * Copyright (C) 1991, 1992 Linus Torvalds
5 * Copyright (C) 2001 Andrea Arcangeli <andrea@suse.de> SuSE
8 #include <linux/config.h>
9 #include <linux/init.h>
11 #include <linux/fcntl.h>
12 #include <linux/slab.h>
13 #include <linux/kmod.h>
14 #include <linux/major.h>
15 #include <linux/devfs_fs_kernel.h>
16 #include <linux/smp_lock.h>
17 #include <linux/highmem.h>
18 #include <linux/blkdev.h>
19 #include <linux/module.h>
20 #include <linux/blkpg.h>
21 #include <linux/buffer_head.h>
22 #include <linux/mpage.h>
23 #include <linux/mount.h>
24 #include <linux/uio.h>
25 #include <linux/namei.h>
26 #include <asm/uaccess.h>
29 struct block_device bdev
;
30 struct inode vfs_inode
;
33 static inline struct bdev_inode
*BDEV_I(struct inode
*inode
)
35 return container_of(inode
, struct bdev_inode
, vfs_inode
);
38 inline struct block_device
*I_BDEV(struct inode
*inode
)
40 return &BDEV_I(inode
)->bdev
;
43 EXPORT_SYMBOL(I_BDEV
);
45 static sector_t
max_block(struct block_device
*bdev
)
47 sector_t retval
= ~((sector_t
)0);
48 loff_t sz
= i_size_read(bdev
->bd_inode
);
51 unsigned int size
= block_size(bdev
);
52 unsigned int sizebits
= blksize_bits(size
);
53 retval
= (sz
>> sizebits
);
58 /* Kill _all_ buffers, dirty or not.. */
59 static void kill_bdev(struct block_device
*bdev
)
61 invalidate_bdev(bdev
, 1);
62 truncate_inode_pages(bdev
->bd_inode
->i_mapping
, 0);
65 int set_blocksize(struct block_device
*bdev
, int size
)
67 /* Size must be a power of two, and between 512 and PAGE_SIZE */
68 if (size
> PAGE_SIZE
|| size
< 512 || (size
& (size
-1)))
71 /* Size cannot be smaller than the size supported by the device */
72 if (size
< bdev_hardsect_size(bdev
))
75 /* Don't change the size if it is same as current */
76 if (bdev
->bd_block_size
!= size
) {
78 bdev
->bd_block_size
= size
;
79 bdev
->bd_inode
->i_blkbits
= blksize_bits(size
);
85 EXPORT_SYMBOL(set_blocksize
);
87 int sb_set_blocksize(struct super_block
*sb
, int size
)
89 if (set_blocksize(sb
->s_bdev
, size
))
91 /* If we get here, we know size is power of two
92 * and it's value is between 512 and PAGE_SIZE */
93 sb
->s_blocksize
= size
;
94 sb
->s_blocksize_bits
= blksize_bits(size
);
95 return sb
->s_blocksize
;
98 EXPORT_SYMBOL(sb_set_blocksize
);
100 int sb_min_blocksize(struct super_block
*sb
, int size
)
102 int minsize
= bdev_hardsect_size(sb
->s_bdev
);
105 return sb_set_blocksize(sb
, size
);
108 EXPORT_SYMBOL(sb_min_blocksize
);
111 blkdev_get_block(struct inode
*inode
, sector_t iblock
,
112 struct buffer_head
*bh
, int create
)
114 if (iblock
>= max_block(I_BDEV(inode
))) {
119 * for reads, we're just trying to fill a partial page.
120 * return a hole, they will have to call get_block again
121 * before they can fill it, and they will get -EIO at that
126 bh
->b_bdev
= I_BDEV(inode
);
127 bh
->b_blocknr
= iblock
;
128 set_buffer_mapped(bh
);
133 blkdev_get_blocks(struct inode
*inode
, sector_t iblock
,
134 struct buffer_head
*bh
, int create
)
136 sector_t end_block
= max_block(I_BDEV(inode
));
137 unsigned long max_blocks
= bh
->b_size
>> inode
->i_blkbits
;
139 if ((iblock
+ max_blocks
) > end_block
) {
140 max_blocks
= end_block
- iblock
;
141 if ((long)max_blocks
<= 0) {
143 return -EIO
; /* write fully beyond EOF */
145 * It is a read which is fully beyond EOF. We return
146 * a !buffer_mapped buffer
152 bh
->b_bdev
= I_BDEV(inode
);
153 bh
->b_blocknr
= iblock
;
154 bh
->b_size
= max_blocks
<< inode
->i_blkbits
;
156 set_buffer_mapped(bh
);
161 blkdev_direct_IO(int rw
, struct kiocb
*iocb
, const struct iovec
*iov
,
162 loff_t offset
, unsigned long nr_segs
)
164 struct file
*file
= iocb
->ki_filp
;
165 struct inode
*inode
= file
->f_mapping
->host
;
167 return blockdev_direct_IO_no_locking(rw
, iocb
, inode
, I_BDEV(inode
),
168 iov
, offset
, nr_segs
, blkdev_get_blocks
, NULL
);
171 static int blkdev_writepage(struct page
*page
, struct writeback_control
*wbc
)
173 return block_write_full_page(page
, blkdev_get_block
, wbc
);
176 static int blkdev_readpage(struct file
* file
, struct page
* page
)
178 return block_read_full_page(page
, blkdev_get_block
);
181 static int blkdev_prepare_write(struct file
*file
, struct page
*page
, unsigned from
, unsigned to
)
183 return block_prepare_write(page
, from
, to
, blkdev_get_block
);
186 static int blkdev_commit_write(struct file
*file
, struct page
*page
, unsigned from
, unsigned to
)
188 return block_commit_write(page
, from
, to
);
193 * for a block special file file->f_dentry->d_inode->i_size is zero
194 * so we compute the size by hand (just as in block_read/write above)
196 static loff_t
block_llseek(struct file
*file
, loff_t offset
, int origin
)
198 struct inode
*bd_inode
= file
->f_mapping
->host
;
202 mutex_lock(&bd_inode
->i_mutex
);
203 size
= i_size_read(bd_inode
);
210 offset
+= file
->f_pos
;
213 if (offset
>= 0 && offset
<= size
) {
214 if (offset
!= file
->f_pos
) {
215 file
->f_pos
= offset
;
219 mutex_unlock(&bd_inode
->i_mutex
);
224 * Filp is never NULL; the only case when ->fsync() is called with
225 * NULL first argument is nfsd_sync_dir() and that's not a directory.
228 static int block_fsync(struct file
*filp
, struct dentry
*dentry
, int datasync
)
230 return sync_blockdev(I_BDEV(filp
->f_mapping
->host
));
237 static __cacheline_aligned_in_smp
DEFINE_SPINLOCK(bdev_lock
);
238 static kmem_cache_t
* bdev_cachep __read_mostly
;
240 static struct inode
*bdev_alloc_inode(struct super_block
*sb
)
242 struct bdev_inode
*ei
= kmem_cache_alloc(bdev_cachep
, SLAB_KERNEL
);
245 return &ei
->vfs_inode
;
248 static void bdev_destroy_inode(struct inode
*inode
)
250 struct bdev_inode
*bdi
= BDEV_I(inode
);
252 bdi
->bdev
.bd_inode_backing_dev_info
= NULL
;
253 kmem_cache_free(bdev_cachep
, bdi
);
256 static void init_once(void * foo
, kmem_cache_t
* cachep
, unsigned long flags
)
258 struct bdev_inode
*ei
= (struct bdev_inode
*) foo
;
259 struct block_device
*bdev
= &ei
->bdev
;
261 if ((flags
& (SLAB_CTOR_VERIFY
|SLAB_CTOR_CONSTRUCTOR
)) ==
262 SLAB_CTOR_CONSTRUCTOR
)
264 memset(bdev
, 0, sizeof(*bdev
));
265 mutex_init(&bdev
->bd_mutex
);
266 mutex_init(&bdev
->bd_mount_mutex
);
267 INIT_LIST_HEAD(&bdev
->bd_inodes
);
268 INIT_LIST_HEAD(&bdev
->bd_list
);
269 inode_init_once(&ei
->vfs_inode
);
273 static inline void __bd_forget(struct inode
*inode
)
275 list_del_init(&inode
->i_devices
);
276 inode
->i_bdev
= NULL
;
277 inode
->i_mapping
= &inode
->i_data
;
280 static void bdev_clear_inode(struct inode
*inode
)
282 struct block_device
*bdev
= &BDEV_I(inode
)->bdev
;
284 spin_lock(&bdev_lock
);
285 while ( (p
= bdev
->bd_inodes
.next
) != &bdev
->bd_inodes
) {
286 __bd_forget(list_entry(p
, struct inode
, i_devices
));
288 list_del_init(&bdev
->bd_list
);
289 spin_unlock(&bdev_lock
);
292 static struct super_operations bdev_sops
= {
293 .statfs
= simple_statfs
,
294 .alloc_inode
= bdev_alloc_inode
,
295 .destroy_inode
= bdev_destroy_inode
,
296 .drop_inode
= generic_delete_inode
,
297 .clear_inode
= bdev_clear_inode
,
300 static struct super_block
*bd_get_sb(struct file_system_type
*fs_type
,
301 int flags
, const char *dev_name
, void *data
)
303 return get_sb_pseudo(fs_type
, "bdev:", &bdev_sops
, 0x62646576);
306 static struct file_system_type bd_type
= {
309 .kill_sb
= kill_anon_super
,
312 static struct vfsmount
*bd_mnt __read_mostly
;
313 struct super_block
*blockdev_superblock
;
315 void __init
bdev_cache_init(void)
318 bdev_cachep
= kmem_cache_create("bdev_cache", sizeof(struct bdev_inode
),
319 0, (SLAB_HWCACHE_ALIGN
|SLAB_RECLAIM_ACCOUNT
|
320 SLAB_MEM_SPREAD
|SLAB_PANIC
),
322 err
= register_filesystem(&bd_type
);
324 panic("Cannot register bdev pseudo-fs");
325 bd_mnt
= kern_mount(&bd_type
);
326 err
= PTR_ERR(bd_mnt
);
328 panic("Cannot create bdev pseudo-fs");
329 blockdev_superblock
= bd_mnt
->mnt_sb
; /* For writeback */
333 * Most likely _very_ bad one - but then it's hardly critical for small
334 * /dev and can be fixed when somebody will need really large one.
335 * Keep in mind that it will be fed through icache hash function too.
337 static inline unsigned long hash(dev_t dev
)
339 return MAJOR(dev
)+MINOR(dev
);
342 static int bdev_test(struct inode
*inode
, void *data
)
344 return BDEV_I(inode
)->bdev
.bd_dev
== *(dev_t
*)data
;
347 static int bdev_set(struct inode
*inode
, void *data
)
349 BDEV_I(inode
)->bdev
.bd_dev
= *(dev_t
*)data
;
353 static LIST_HEAD(all_bdevs
);
355 struct block_device
*bdget(dev_t dev
)
357 struct block_device
*bdev
;
360 inode
= iget5_locked(bd_mnt
->mnt_sb
, hash(dev
),
361 bdev_test
, bdev_set
, &dev
);
366 bdev
= &BDEV_I(inode
)->bdev
;
368 if (inode
->i_state
& I_NEW
) {
369 bdev
->bd_contains
= NULL
;
370 bdev
->bd_inode
= inode
;
371 bdev
->bd_block_size
= (1 << inode
->i_blkbits
);
372 bdev
->bd_part_count
= 0;
373 bdev
->bd_invalidated
= 0;
374 inode
->i_mode
= S_IFBLK
;
376 inode
->i_bdev
= bdev
;
377 inode
->i_data
.a_ops
= &def_blk_aops
;
378 mapping_set_gfp_mask(&inode
->i_data
, GFP_USER
);
379 inode
->i_data
.backing_dev_info
= &default_backing_dev_info
;
380 spin_lock(&bdev_lock
);
381 list_add(&bdev
->bd_list
, &all_bdevs
);
382 spin_unlock(&bdev_lock
);
383 unlock_new_inode(inode
);
388 EXPORT_SYMBOL(bdget
);
390 long nr_blockdev_pages(void)
394 spin_lock(&bdev_lock
);
395 list_for_each(p
, &all_bdevs
) {
396 struct block_device
*bdev
;
397 bdev
= list_entry(p
, struct block_device
, bd_list
);
398 ret
+= bdev
->bd_inode
->i_mapping
->nrpages
;
400 spin_unlock(&bdev_lock
);
404 void bdput(struct block_device
*bdev
)
406 iput(bdev
->bd_inode
);
409 EXPORT_SYMBOL(bdput
);
411 static struct block_device
*bd_acquire(struct inode
*inode
)
413 struct block_device
*bdev
;
414 spin_lock(&bdev_lock
);
415 bdev
= inode
->i_bdev
;
416 if (bdev
&& igrab(bdev
->bd_inode
)) {
417 spin_unlock(&bdev_lock
);
420 spin_unlock(&bdev_lock
);
421 bdev
= bdget(inode
->i_rdev
);
423 spin_lock(&bdev_lock
);
426 inode
->i_bdev
= bdev
;
427 inode
->i_mapping
= bdev
->bd_inode
->i_mapping
;
428 list_add(&inode
->i_devices
, &bdev
->bd_inodes
);
429 spin_unlock(&bdev_lock
);
434 /* Call when you free inode */
436 void bd_forget(struct inode
*inode
)
438 spin_lock(&bdev_lock
);
441 spin_unlock(&bdev_lock
);
444 int bd_claim(struct block_device
*bdev
, void *holder
)
447 spin_lock(&bdev_lock
);
449 /* first decide result */
450 if (bdev
->bd_holder
== holder
)
451 res
= 0; /* already a holder */
452 else if (bdev
->bd_holder
!= NULL
)
453 res
= -EBUSY
; /* held by someone else */
454 else if (bdev
->bd_contains
== bdev
)
455 res
= 0; /* is a whole device which isn't held */
457 else if (bdev
->bd_contains
->bd_holder
== bd_claim
)
458 res
= 0; /* is a partition of a device that is being partitioned */
459 else if (bdev
->bd_contains
->bd_holder
!= NULL
)
460 res
= -EBUSY
; /* is a partition of a held device */
462 res
= 0; /* is a partition of an un-held device */
464 /* now impose change */
466 /* note that for a whole device bd_holders
467 * will be incremented twice, and bd_holder will
468 * be set to bd_claim before being set to holder
470 bdev
->bd_contains
->bd_holders
++;
471 bdev
->bd_contains
->bd_holder
= bd_claim
;
473 bdev
->bd_holder
= holder
;
475 spin_unlock(&bdev_lock
);
479 EXPORT_SYMBOL(bd_claim
);
481 void bd_release(struct block_device
*bdev
)
483 spin_lock(&bdev_lock
);
484 if (!--bdev
->bd_contains
->bd_holders
)
485 bdev
->bd_contains
->bd_holder
= NULL
;
486 if (!--bdev
->bd_holders
)
487 bdev
->bd_holder
= NULL
;
488 spin_unlock(&bdev_lock
);
491 EXPORT_SYMBOL(bd_release
);
494 * Tries to open block device by device number. Use it ONLY if you
495 * really do not have anything better - i.e. when you are behind a
496 * truly sucky interface and all you are given is a device number. _Never_
497 * to be used for internal purposes. If you ever need it - reconsider
500 struct block_device
*open_by_devnum(dev_t dev
, unsigned mode
)
502 struct block_device
*bdev
= bdget(dev
);
504 int flags
= mode
& FMODE_WRITE
? O_RDWR
: O_RDONLY
;
506 err
= blkdev_get(bdev
, mode
, flags
);
507 return err
? ERR_PTR(err
) : bdev
;
510 EXPORT_SYMBOL(open_by_devnum
);
513 * This routine checks whether a removable media has been changed,
514 * and invalidates all buffer-cache-entries in that case. This
515 * is a relatively slow routine, so we have to try to minimize using
516 * it. Thus it is called only upon a 'mount' or 'open'. This
517 * is the best way of combining speed and utility, I think.
518 * People changing diskettes in the middle of an operation deserve
521 int check_disk_change(struct block_device
*bdev
)
523 struct gendisk
*disk
= bdev
->bd_disk
;
524 struct block_device_operations
* bdops
= disk
->fops
;
526 if (!bdops
->media_changed
)
528 if (!bdops
->media_changed(bdev
->bd_disk
))
531 if (__invalidate_device(bdev
))
532 printk("VFS: busy inodes on changed media.\n");
534 if (bdops
->revalidate_disk
)
535 bdops
->revalidate_disk(bdev
->bd_disk
);
536 if (bdev
->bd_disk
->minors
> 1)
537 bdev
->bd_invalidated
= 1;
541 EXPORT_SYMBOL(check_disk_change
);
543 void bd_set_size(struct block_device
*bdev
, loff_t size
)
545 unsigned bsize
= bdev_hardsect_size(bdev
);
547 bdev
->bd_inode
->i_size
= size
;
548 while (bsize
< PAGE_CACHE_SIZE
) {
553 bdev
->bd_block_size
= bsize
;
554 bdev
->bd_inode
->i_blkbits
= blksize_bits(bsize
);
556 EXPORT_SYMBOL(bd_set_size
);
558 static int do_open(struct block_device
*bdev
, struct file
*file
)
560 struct module
*owner
= NULL
;
561 struct gendisk
*disk
;
565 file
->f_mapping
= bdev
->bd_inode
->i_mapping
;
567 disk
= get_gendisk(bdev
->bd_dev
, &part
);
573 owner
= disk
->fops
->owner
;
575 mutex_lock(&bdev
->bd_mutex
);
576 if (!bdev
->bd_openers
) {
577 bdev
->bd_disk
= disk
;
578 bdev
->bd_contains
= bdev
;
580 struct backing_dev_info
*bdi
;
581 if (disk
->fops
->open
) {
582 ret
= disk
->fops
->open(bdev
->bd_inode
, file
);
586 if (!bdev
->bd_openers
) {
587 bd_set_size(bdev
,(loff_t
)get_capacity(disk
)<<9);
588 bdi
= blk_get_backing_dev_info(bdev
);
590 bdi
= &default_backing_dev_info
;
591 bdev
->bd_inode
->i_data
.backing_dev_info
= bdi
;
593 if (bdev
->bd_invalidated
)
594 rescan_partitions(disk
, bdev
);
597 struct block_device
*whole
;
598 whole
= bdget_disk(disk
, 0);
602 ret
= blkdev_get(whole
, file
->f_mode
, file
->f_flags
);
605 bdev
->bd_contains
= whole
;
606 mutex_lock(&whole
->bd_mutex
);
607 whole
->bd_part_count
++;
608 p
= disk
->part
[part
- 1];
609 bdev
->bd_inode
->i_data
.backing_dev_info
=
610 whole
->bd_inode
->i_data
.backing_dev_info
;
611 if (!(disk
->flags
& GENHD_FL_UP
) || !p
|| !p
->nr_sects
) {
612 whole
->bd_part_count
--;
613 mutex_unlock(&whole
->bd_mutex
);
617 kobject_get(&p
->kobj
);
619 bd_set_size(bdev
, (loff_t
) p
->nr_sects
<< 9);
620 mutex_unlock(&whole
->bd_mutex
);
625 if (bdev
->bd_contains
== bdev
) {
626 if (bdev
->bd_disk
->fops
->open
) {
627 ret
= bdev
->bd_disk
->fops
->open(bdev
->bd_inode
, file
);
631 if (bdev
->bd_invalidated
)
632 rescan_partitions(bdev
->bd_disk
, bdev
);
634 mutex_lock(&bdev
->bd_contains
->bd_mutex
);
635 bdev
->bd_contains
->bd_part_count
++;
636 mutex_unlock(&bdev
->bd_contains
->bd_mutex
);
640 mutex_unlock(&bdev
->bd_mutex
);
645 bdev
->bd_disk
= NULL
;
646 bdev
->bd_inode
->i_data
.backing_dev_info
= &default_backing_dev_info
;
647 if (bdev
!= bdev
->bd_contains
)
648 blkdev_put(bdev
->bd_contains
);
649 bdev
->bd_contains
= NULL
;
653 mutex_unlock(&bdev
->bd_mutex
);
660 int blkdev_get(struct block_device
*bdev
, mode_t mode
, unsigned flags
)
663 * This crockload is due to bad choice of ->open() type.
665 * For now, block device ->open() routine must _not_
666 * examine anything in 'inode' argument except ->i_rdev.
668 struct file fake_file
= {};
669 struct dentry fake_dentry
= {};
670 fake_file
.f_mode
= mode
;
671 fake_file
.f_flags
= flags
;
672 fake_file
.f_dentry
= &fake_dentry
;
673 fake_dentry
.d_inode
= bdev
->bd_inode
;
675 return do_open(bdev
, &fake_file
);
678 EXPORT_SYMBOL(blkdev_get
);
680 static int blkdev_open(struct inode
* inode
, struct file
* filp
)
682 struct block_device
*bdev
;
686 * Preserve backwards compatibility and allow large file access
687 * even if userspace doesn't ask for it explicitly. Some mkfs
688 * binary needs it. We might want to drop this workaround
689 * during an unstable branch.
691 filp
->f_flags
|= O_LARGEFILE
;
693 bdev
= bd_acquire(inode
);
695 res
= do_open(bdev
, filp
);
699 if (!(filp
->f_flags
& O_EXCL
) )
702 if (!(res
= bd_claim(bdev
, filp
)))
709 int blkdev_put(struct block_device
*bdev
)
712 struct inode
*bd_inode
= bdev
->bd_inode
;
713 struct gendisk
*disk
= bdev
->bd_disk
;
715 mutex_lock(&bdev
->bd_mutex
);
717 if (!--bdev
->bd_openers
) {
721 if (bdev
->bd_contains
== bdev
) {
722 if (disk
->fops
->release
)
723 ret
= disk
->fops
->release(bd_inode
, NULL
);
725 mutex_lock(&bdev
->bd_contains
->bd_mutex
);
726 bdev
->bd_contains
->bd_part_count
--;
727 mutex_unlock(&bdev
->bd_contains
->bd_mutex
);
729 if (!bdev
->bd_openers
) {
730 struct module
*owner
= disk
->fops
->owner
;
735 if (bdev
->bd_contains
!= bdev
) {
736 kobject_put(&bdev
->bd_part
->kobj
);
737 bdev
->bd_part
= NULL
;
739 bdev
->bd_disk
= NULL
;
740 bdev
->bd_inode
->i_data
.backing_dev_info
= &default_backing_dev_info
;
741 if (bdev
!= bdev
->bd_contains
) {
742 blkdev_put(bdev
->bd_contains
);
744 bdev
->bd_contains
= NULL
;
747 mutex_unlock(&bdev
->bd_mutex
);
752 EXPORT_SYMBOL(blkdev_put
);
754 static int blkdev_close(struct inode
* inode
, struct file
* filp
)
756 struct block_device
*bdev
= I_BDEV(filp
->f_mapping
->host
);
757 if (bdev
->bd_holder
== filp
)
759 return blkdev_put(bdev
);
762 static ssize_t
blkdev_file_write(struct file
*file
, const char __user
*buf
,
763 size_t count
, loff_t
*ppos
)
765 struct iovec local_iov
= { .iov_base
= (void __user
*)buf
, .iov_len
= count
};
767 return generic_file_write_nolock(file
, &local_iov
, 1, ppos
);
770 static ssize_t
blkdev_file_aio_write(struct kiocb
*iocb
, const char __user
*buf
,
771 size_t count
, loff_t pos
)
773 struct iovec local_iov
= { .iov_base
= (void __user
*)buf
, .iov_len
= count
};
775 return generic_file_aio_write_nolock(iocb
, &local_iov
, 1, &iocb
->ki_pos
);
778 static long block_ioctl(struct file
*file
, unsigned cmd
, unsigned long arg
)
780 return blkdev_ioctl(file
->f_mapping
->host
, file
, cmd
, arg
);
783 struct address_space_operations def_blk_aops
= {
784 .readpage
= blkdev_readpage
,
785 .writepage
= blkdev_writepage
,
786 .sync_page
= block_sync_page
,
787 .prepare_write
= blkdev_prepare_write
,
788 .commit_write
= blkdev_commit_write
,
789 .writepages
= generic_writepages
,
790 .direct_IO
= blkdev_direct_IO
,
793 struct file_operations def_blk_fops
= {
795 .release
= blkdev_close
,
796 .llseek
= block_llseek
,
797 .read
= generic_file_read
,
798 .write
= blkdev_file_write
,
799 .aio_read
= generic_file_aio_read
,
800 .aio_write
= blkdev_file_aio_write
,
801 .mmap
= generic_file_mmap
,
802 .fsync
= block_fsync
,
803 .unlocked_ioctl
= block_ioctl
,
805 .compat_ioctl
= compat_blkdev_ioctl
,
807 .readv
= generic_file_readv
,
808 .writev
= generic_file_write_nolock
,
809 .sendfile
= generic_file_sendfile
,
812 int ioctl_by_bdev(struct block_device
*bdev
, unsigned cmd
, unsigned long arg
)
815 mm_segment_t old_fs
= get_fs();
817 res
= blkdev_ioctl(bdev
->bd_inode
, NULL
, cmd
, arg
);
822 EXPORT_SYMBOL(ioctl_by_bdev
);
825 * lookup_bdev - lookup a struct block_device by name
827 * @path: special file representing the block device
829 * Get a reference to the blockdevice at @path in the current
830 * namespace if possible and return it. Return ERR_PTR(error)
833 struct block_device
*lookup_bdev(const char *path
)
835 struct block_device
*bdev
;
841 return ERR_PTR(-EINVAL
);
843 error
= path_lookup(path
, LOOKUP_FOLLOW
, &nd
);
845 return ERR_PTR(error
);
847 inode
= nd
.dentry
->d_inode
;
849 if (!S_ISBLK(inode
->i_mode
))
852 if (nd
.mnt
->mnt_flags
& MNT_NODEV
)
855 bdev
= bd_acquire(inode
);
862 bdev
= ERR_PTR(error
);
867 * open_bdev_excl - open a block device by name and set it up for use
869 * @path: special file representing the block device
870 * @flags: %MS_RDONLY for opening read-only
871 * @holder: owner for exclusion
873 * Open the blockdevice described by the special file at @path, claim it
876 struct block_device
*open_bdev_excl(const char *path
, int flags
, void *holder
)
878 struct block_device
*bdev
;
879 mode_t mode
= FMODE_READ
;
882 bdev
= lookup_bdev(path
);
886 if (!(flags
& MS_RDONLY
))
888 error
= blkdev_get(bdev
, mode
, 0);
890 return ERR_PTR(error
);
892 if (!(flags
& MS_RDONLY
) && bdev_read_only(bdev
))
894 error
= bd_claim(bdev
, holder
);
902 return ERR_PTR(error
);
905 EXPORT_SYMBOL(open_bdev_excl
);
908 * close_bdev_excl - release a blockdevice openen by open_bdev_excl()
910 * @bdev: blockdevice to close
912 * This is the counterpart to open_bdev_excl().
914 void close_bdev_excl(struct block_device
*bdev
)
920 EXPORT_SYMBOL(close_bdev_excl
);