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/*
* linux/fs/block_dev.c
*
* Copyright (C) 1991, 1992 Linus Torvalds
* Copyright (C) 2001 Andrea Arcangeli <andrea@suse.de> SuSE
*/
#include <linux/config.h>
#include <linux/init.h>
#include <linux/mm.h>
#include <linux/locks.h>
#include <linux/fcntl.h>
#include <linux/slab.h>
#include <linux/kmod.h>
#include <linux/major.h>
#include <linux/devfs_fs_kernel.h>
#include <linux/smp_lock.h>
#include <linux/iobuf.h>
#include <linux/highmem.h>
#include <linux/blkdev.h>
#include <linux/module.h>
#include <asm/uaccess.h>
#define MAX_BUF_PER_PAGE (PAGE_CACHE_SIZE / 512)
static unsigned long max_block(kdev_t dev)
{
unsigned int retval = ~0U;
int major = MAJOR(dev);
if (blk_size[major]) {
int minor = MINOR(dev);
unsigned int blocks = blk_size[major][minor];
if (blocks) {
unsigned int size = block_size(dev);
unsigned int sizebits = blksize_bits(size);
blocks += (size-1) >> BLOCK_SIZE_BITS;
retval = blocks << (BLOCK_SIZE_BITS - sizebits);
if (sizebits > BLOCK_SIZE_BITS)
retval = blocks >> (sizebits - BLOCK_SIZE_BITS);
}
}
return retval;
}
static loff_t blkdev_size(kdev_t dev)
{
unsigned int blocks = ~0U;
int major = MAJOR(dev);
if (blk_size[major]) {
int minor = MINOR(dev);
blocks = blk_size[major][minor];
}
return (loff_t) blocks << BLOCK_SIZE_BITS;
}
/* Kill _all_ buffers, dirty or not.. */
static void kill_bdev(struct block_device *bdev)
{
invalidate_bdev(bdev, 1);
truncate_inode_pages(bdev->bd_inode->i_mapping, 0);
}
int set_blocksize(kdev_t dev, int size)
{
int oldsize;
struct block_device *bdev;
/* Size must be a power of two, and between 512 and PAGE_SIZE */
if (size > PAGE_SIZE || size < 512 || (size & (size-1)))
return -EINVAL;
/* Size cannot be smaller than the size supported by the device */
if (size < get_hardsect_size(dev))
return -EINVAL;
/* No blocksize array? Implies hardcoded BLOCK_SIZE */
if (!blksize_size[MAJOR(dev)]) {
if (size == BLOCK_SIZE)
return 0;
return -EINVAL;
}
oldsize = blksize_size[MAJOR(dev)][MINOR(dev)];
if (oldsize == size)
return 0;
if (!oldsize && size == BLOCK_SIZE) {
blksize_size[MAJOR(dev)][MINOR(dev)] = size;
return 0;
}
/* Ok, we're actually changing the blocksize.. */
bdev = bdget(dev);
sync_buffers(dev, 2);
blksize_size[MAJOR(dev)][MINOR(dev)] = size;
bdev->bd_inode->i_blkbits = blksize_bits(size);
kill_bdev(bdev);
bdput(bdev);
return 0;
}
static int blkdev_get_block(struct inode * inode, long iblock, struct buffer_head * bh, int create)
{
if (iblock >= max_block(inode->i_rdev))
return -EIO;
bh->b_dev = inode->i_rdev;
bh->b_blocknr = iblock;
bh->b_state |= 1UL << BH_Mapped;
return 0;
}
static int blkdev_direct_IO(int rw, struct inode * inode, struct kiobuf * iobuf, unsigned long blocknr, int blocksize)
{
return generic_direct_IO(rw, inode, iobuf, blocknr, blocksize, blkdev_get_block);
}
static int blkdev_writepage(struct page * page)
{
return block_write_full_page(page, blkdev_get_block);
}
static int blkdev_readpage(struct file * file, struct page * page)
{
return block_read_full_page(page, blkdev_get_block);
}
static int blkdev_prepare_write(struct file *file, struct page *page, unsigned from, unsigned to)
{
return block_prepare_write(page, from, to, blkdev_get_block);
}
static int blkdev_commit_write(struct file *file, struct page *page, unsigned from, unsigned to)
{
return block_commit_write(page, from, to);
}
/*
* private llseek:
* for a block special file file->f_dentry->d_inode->i_size is zero
* so we compute the size by hand (just as in block_read/write above)
*/
static loff_t block_llseek(struct file *file, loff_t offset, int origin)
{
/* ewww */
loff_t size = file->f_dentry->d_inode->i_bdev->bd_inode->i_size;
loff_t retval;
switch (origin) {
case 2:
offset += size;
break;
case 1:
offset += file->f_pos;
}
retval = -EINVAL;
if (offset >= 0 && offset <= size) {
if (offset != file->f_pos) {
file->f_pos = offset;
file->f_reada = 0;
file->f_version = ++event;
}
retval = offset;
}
return retval;
}
static int __block_fsync(struct inode * inode)
{
int ret, err;
ret = filemap_fdatasync(inode->i_mapping);
err = sync_buffers(inode->i_rdev, 1);
if (err && !ret)
ret = err;
err = filemap_fdatawait(inode->i_mapping);
if (err && !ret)
ret = err;
return ret;
}
/*
* Filp may be NULL when we are called by an msync of a vma
* since the vma has no handle.
*/
static int block_fsync(struct file *filp, struct dentry *dentry, int datasync)
{
struct inode * inode = dentry->d_inode;
return __block_fsync(inode);
}
/*
* pseudo-fs
*/
static struct super_block *bd_read_super(struct super_block *sb, void *data, int silent)
{
static struct super_operations sops = {};
struct inode *root = new_inode(sb);
if (!root)
return NULL;
root->i_mode = S_IFDIR | S_IRUSR | S_IWUSR;
root->i_uid = root->i_gid = 0;
root->i_atime = root->i_mtime = root->i_ctime = CURRENT_TIME;
sb->s_maxbytes = ~0ULL;
sb->s_blocksize = 1024;
sb->s_blocksize_bits = 10;
sb->s_magic = 0x62646576;
sb->s_op = &sops;
sb->s_root = d_alloc(NULL, &(const struct qstr) { "bdev:", 5, 0 });
if (!sb->s_root) {
iput(root);
return NULL;
}
sb->s_root->d_sb = sb;
sb->s_root->d_parent = sb->s_root;
d_instantiate(sb->s_root, root);
return sb;
}
static DECLARE_FSTYPE(bd_type, "bdev", bd_read_super, FS_NOMOUNT);
static struct vfsmount *bd_mnt;
/*
* bdev cache handling - shamelessly stolen from inode.c
* We use smaller hashtable, though.
*/
#define HASH_BITS 6
#define HASH_SIZE (1UL << HASH_BITS)
#define HASH_MASK (HASH_SIZE-1)
static struct list_head bdev_hashtable[HASH_SIZE];
static spinlock_t bdev_lock __cacheline_aligned_in_smp = SPIN_LOCK_UNLOCKED;
static kmem_cache_t * bdev_cachep;
#define alloc_bdev() \
((struct block_device *) kmem_cache_alloc(bdev_cachep, SLAB_KERNEL))
#define destroy_bdev(bdev) kmem_cache_free(bdev_cachep, (bdev))
static void init_once(void * foo, kmem_cache_t * cachep, unsigned long flags)
{
struct block_device * bdev = (struct block_device *) foo;
if ((flags & (SLAB_CTOR_VERIFY|SLAB_CTOR_CONSTRUCTOR)) ==
SLAB_CTOR_CONSTRUCTOR)
{
memset(bdev, 0, sizeof(*bdev));
sema_init(&bdev->bd_sem, 1);
INIT_LIST_HEAD(&bdev->bd_inodes);
}
}
void __init bdev_cache_init(void)
{
int i, err;
struct list_head *head = bdev_hashtable;
i = HASH_SIZE;
do {
INIT_LIST_HEAD(head);
head++;
i--;
} while (i);
bdev_cachep = kmem_cache_create("bdev_cache",
sizeof(struct block_device),
0, SLAB_HWCACHE_ALIGN, init_once,
NULL);
if (!bdev_cachep)
panic("Cannot create bdev_cache SLAB cache");
err = register_filesystem(&bd_type);
if (err)
panic("Cannot register bdev pseudo-fs");
bd_mnt = kern_mount(&bd_type);
err = PTR_ERR(bd_mnt);
if (IS_ERR(bd_mnt))
panic("Cannot create bdev pseudo-fs");
}
/*
* Most likely _very_ bad one - but then it's hardly critical for small
* /dev and can be fixed when somebody will need really large one.
*/
static inline unsigned long hash(dev_t dev)
{
unsigned long tmp = dev;
tmp = tmp + (tmp >> HASH_BITS) + (tmp >> HASH_BITS*2);
return tmp & HASH_MASK;
}
static struct block_device *bdfind(dev_t dev, struct list_head *head)
{
struct list_head *p;
struct block_device *bdev;
for (p=head->next; p!=head; p=p->next) {
bdev = list_entry(p, struct block_device, bd_hash);
if (bdev->bd_dev != dev)
continue;
atomic_inc(&bdev->bd_count);
return bdev;
}
return NULL;
}
struct block_device *bdget(dev_t dev)
{
struct list_head * head = bdev_hashtable + hash(dev);
struct block_device *bdev, *new_bdev;
spin_lock(&bdev_lock);
bdev = bdfind(dev, head);
spin_unlock(&bdev_lock);
if (bdev)
return bdev;
new_bdev = alloc_bdev();
if (new_bdev) {
struct inode *inode = new_inode(bd_mnt->mnt_sb);
if (inode) {
kdev_t kdev = to_kdev_t(dev);
atomic_set(&new_bdev->bd_count,1);
new_bdev->bd_dev = dev;
new_bdev->bd_op = NULL;
new_bdev->bd_inode = inode;
inode->i_rdev = kdev;
inode->i_dev = kdev;
inode->i_bdev = new_bdev;
inode->i_data.a_ops = &def_blk_aops;
inode->i_data.gfp_mask = GFP_USER;
inode->i_mode = S_IFBLK;
spin_lock(&bdev_lock);
bdev = bdfind(dev, head);
if (!bdev) {
list_add(&new_bdev->bd_hash, head);
spin_unlock(&bdev_lock);
return new_bdev;
}
spin_unlock(&bdev_lock);
iput(new_bdev->bd_inode);
}
destroy_bdev(new_bdev);
}
return bdev;
}
static inline void __bd_forget(struct inode *inode)
{
list_del_init(&inode->i_devices);
inode->i_bdev = NULL;
inode->i_mapping = &inode->i_data;
}
void bdput(struct block_device *bdev)
{
if (atomic_dec_and_lock(&bdev->bd_count, &bdev_lock)) {
struct list_head *p;
if (bdev->bd_openers)
BUG();
list_del(&bdev->bd_hash);
while ( (p = bdev->bd_inodes.next) != &bdev->bd_inodes ) {
__bd_forget(list_entry(p, struct inode, i_devices));
}
spin_unlock(&bdev_lock);
iput(bdev->bd_inode);
destroy_bdev(bdev);
}
}
int bd_acquire(struct inode *inode)
{
struct block_device *bdev;
spin_lock(&bdev_lock);
if (inode->i_bdev) {
atomic_inc(&inode->i_bdev->bd_count);
spin_unlock(&bdev_lock);
return 0;
}
spin_unlock(&bdev_lock);
bdev = bdget(kdev_t_to_nr(inode->i_rdev));
if (!bdev)
return -ENOMEM;
spin_lock(&bdev_lock);
if (!inode->i_bdev) {
inode->i_bdev = bdev;
inode->i_mapping = bdev->bd_inode->i_mapping;
list_add(&inode->i_devices, &bdev->bd_inodes);
} else if (inode->i_bdev != bdev)
BUG();
spin_unlock(&bdev_lock);
return 0;
}
/* Call when you free inode */
void bd_forget(struct inode *inode)
{
spin_lock(&bdev_lock);
if (inode->i_bdev)
__bd_forget(inode);
spin_unlock(&bdev_lock);
}
static struct {
const char *name;
struct block_device_operations *bdops;
} blkdevs[MAX_BLKDEV];
int get_blkdev_list(char * p)
{
int i;
int len;
len = sprintf(p, "\nBlock devices:\n");
for (i = 0; i < MAX_BLKDEV ; i++) {
if (blkdevs[i].bdops) {
len += sprintf(p+len, "%3d %s\n", i, blkdevs[i].name);
}
}
return len;
}
/*
Return the function table of a device.
Load the driver if needed.
*/
const struct block_device_operations * get_blkfops(unsigned int major)
{
const struct block_device_operations *ret = NULL;
/* major 0 is used for non-device mounts */
if (major && major < MAX_BLKDEV) {
#ifdef CONFIG_KMOD
if (!blkdevs[major].bdops) {
char name[20];
sprintf(name, "block-major-%d", major);
request_module(name);
}
#endif
ret = blkdevs[major].bdops;
}
return ret;
}
int register_blkdev(unsigned int major, const char * name, struct block_device_operations *bdops)
{
if (major == 0) {
for (major = MAX_BLKDEV-1; major > 0; major--) {
if (blkdevs[major].bdops == NULL) {
blkdevs[major].name = name;
blkdevs[major].bdops = bdops;
return major;
}
}
return -EBUSY;
}
if (major >= MAX_BLKDEV)
return -EINVAL;
if (blkdevs[major].bdops && blkdevs[major].bdops != bdops)
return -EBUSY;
blkdevs[major].name = name;
blkdevs[major].bdops = bdops;
return 0;
}
int unregister_blkdev(unsigned int major, const char * name)
{
if (major >= MAX_BLKDEV)
return -EINVAL;
if (!blkdevs[major].bdops)
return -EINVAL;
if (strcmp(blkdevs[major].name, name))
return -EINVAL;
blkdevs[major].name = NULL;
blkdevs[major].bdops = NULL;
return 0;
}
/*
* This routine checks whether a removable media has been changed,
* and invalidates all buffer-cache-entries in that case. This
* is a relatively slow routine, so we have to try to minimize using
* it. Thus it is called only upon a 'mount' or 'open'. This
* is the best way of combining speed and utility, I think.
* People changing diskettes in the middle of an operation deserve
* to lose :-)
*/
int check_disk_change(kdev_t dev)
{
int i;
const struct block_device_operations * bdops = NULL;
i = MAJOR(dev);
if (i < MAX_BLKDEV)
bdops = blkdevs[i].bdops;
if (bdops == NULL) {
devfs_handle_t de;
de = devfs_find_handle (NULL, NULL, i, MINOR (dev),
DEVFS_SPECIAL_BLK, 0);
if (de) {
bdops = devfs_get_ops (de);
devfs_put_ops (de); /* We're running in owner module */
}
}
if (bdops == NULL)
return 0;
if (bdops->check_media_change == NULL)
return 0;
if (!bdops->check_media_change(dev))
return 0;
printk(KERN_DEBUG "VFS: Disk change detected on device %s\n",
bdevname(dev));
if (invalidate_device(dev, 0))
printk("VFS: busy inodes on changed media.\n");
if (bdops->revalidate)
bdops->revalidate(dev);
return 1;
}
int ioctl_by_bdev(struct block_device *bdev, unsigned cmd, unsigned long arg)
{
int res;
mm_segment_t old_fs = get_fs();
if (!bdev->bd_op->ioctl)
return -EINVAL;
set_fs(KERNEL_DS);
res = bdev->bd_op->ioctl(bdev->bd_inode, NULL, cmd, arg);
set_fs(old_fs);
return res;
}
static int do_open(struct block_device *bdev, struct inode *inode, struct file *file)
{
int ret = -ENXIO;
kdev_t dev = to_kdev_t(bdev->bd_dev);
down(&bdev->bd_sem);
lock_kernel();
if (!bdev->bd_op)
bdev->bd_op = get_blkfops(MAJOR(dev));
if (bdev->bd_op) {
ret = 0;
if (bdev->bd_op->owner)
__MOD_INC_USE_COUNT(bdev->bd_op->owner);
if (bdev->bd_op->open)
ret = bdev->bd_op->open(inode, file);
if (!ret) {
bdev->bd_openers++;
bdev->bd_inode->i_size = blkdev_size(dev);
bdev->bd_inode->i_blkbits = blksize_bits(block_size(dev));
} else {
if (bdev->bd_op->owner)
__MOD_DEC_USE_COUNT(bdev->bd_op->owner);
if (!bdev->bd_openers)
bdev->bd_op = NULL;
}
}
unlock_kernel();
up(&bdev->bd_sem);
if (ret)
bdput(bdev);
return ret;
}
int blkdev_get(struct block_device *bdev, mode_t mode, unsigned flags, int kind)
{
/*
* This crockload is due to bad choice of ->open() type.
* It will go away.
* For now, block device ->open() routine must _not_
* examine anything in 'inode' argument except ->i_rdev.
*/
struct file fake_file = {};
struct dentry fake_dentry = {};
fake_file.f_mode = mode;
fake_file.f_flags = flags;
fake_file.f_dentry = &fake_dentry;
fake_dentry.d_inode = bdev->bd_inode;
return do_open(bdev, bdev->bd_inode, &fake_file);
}
int blkdev_open(struct inode * inode, struct file * filp)
{
struct block_device *bdev;
/*
* Preserve backwards compatibility and allow large file access
* even if userspace doesn't ask for it explicitly. Some mkfs
* binary needs it. We might want to drop this workaround
* during an unstable branch.
*/
filp->f_flags |= O_LARGEFILE;
bd_acquire(inode);
bdev = inode->i_bdev;
return do_open(bdev, inode, filp);
}
int blkdev_put(struct block_device *bdev, int kind)
{
int ret = 0;
kdev_t rdev = to_kdev_t(bdev->bd_dev); /* this should become bdev */
struct inode *bd_inode = bdev->bd_inode;
down(&bdev->bd_sem);
lock_kernel();
if (kind == BDEV_FILE)
__block_fsync(bd_inode);
else if (kind == BDEV_FS)
fsync_no_super(rdev);
if (!--bdev->bd_openers)
kill_bdev(bdev);
if (bdev->bd_op->release)
ret = bdev->bd_op->release(bd_inode, NULL);
if (bdev->bd_op->owner)
__MOD_DEC_USE_COUNT(bdev->bd_op->owner);
if (!bdev->bd_openers)
bdev->bd_op = NULL;
unlock_kernel();
up(&bdev->bd_sem);
bdput(bdev);
return ret;
}
int blkdev_close(struct inode * inode, struct file * filp)
{
return blkdev_put(inode->i_bdev, BDEV_FILE);
}
static int blkdev_ioctl(struct inode *inode, struct file *file, unsigned cmd,
unsigned long arg)
{
if (inode->i_bdev->bd_op->ioctl)
return inode->i_bdev->bd_op->ioctl(inode, file, cmd, arg);
return -EINVAL;
}
struct address_space_operations def_blk_aops = {
readpage: blkdev_readpage,
writepage: blkdev_writepage,
sync_page: block_sync_page,
prepare_write: blkdev_prepare_write,
commit_write: blkdev_commit_write,
direct_IO: blkdev_direct_IO,
};
struct file_operations def_blk_fops = {
open: blkdev_open,
release: blkdev_close,
llseek: block_llseek,
read: generic_file_read,
write: generic_file_write,
mmap: generic_file_mmap,
fsync: block_fsync,
ioctl: blkdev_ioctl,
};
const char * bdevname(kdev_t dev)
{
static char buffer[32];
const char * name = blkdevs[MAJOR(dev)].name;
if (!name)
name = "unknown-block";
sprintf(buffer, "%s(%d,%d)", name, MAJOR(dev), MINOR(dev));
return buffer;
}
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