blob: 8fb0171c2e67c8c31fcce00ab52001c8fc52575d [file] [log] [blame]
/*
* ramdisk.c - Multiple RAM disk driver - gzip-loading version - v. 0.8 beta.
*
* (C) Chad Page, Theodore Ts'o, et. al, 1995.
*
* This RAM disk is designed to have filesystems created on it and mounted
* just like a regular floppy disk.
*
* It also does something suggested by Linus: use the buffer cache as the
* RAM disk data. This makes it possible to dynamically allocate the RAM disk
* buffer - with some consequences I have to deal with as I write this.
*
* This code is based on the original ramdisk.c, written mostly by
* Theodore Ts'o (TYT) in 1991. The code was largely rewritten by
* Chad Page to use the buffer cache to store the RAM disk data in
* 1995; Theodore then took over the driver again, and cleaned it up
* for inclusion in the mainline kernel.
*
* The original CRAMDISK code was written by Richard Lyons, and
* adapted by Chad Page to use the new RAM disk interface. Theodore
* Ts'o rewrote it so that both the compressed RAM disk loader and the
* kernel decompressor uses the same inflate.c codebase. The RAM disk
* loader now also loads into a dynamic (buffer cache based) RAM disk,
* not the old static RAM disk. Support for the old static RAM disk has
* been completely removed.
*
* Loadable module support added by Tom Dyas.
*
* Further cleanups by Chad Page (page0588@sundance.sjsu.edu):
* Cosmetic changes in #ifdef MODULE, code movement, etc.
* When the RAM disk module is removed, free the protected buffers
* Default RAM disk size changed to 2.88 MB
*
* Added initrd: Werner Almesberger & Hans Lermen, Feb '96
*
* 4/25/96 : Made RAM disk size a parameter (default is now 4 MB)
* - Chad Page
*
* Add support for fs images split across >1 disk, Paul Gortmaker, Mar '98
*
* Make block size and block size shift for RAM disks a global macro
* and set blk_size for -ENOSPC, Werner Fink <werner@suse.de>, Apr '99
*/
#include <linux/config.h>
#include <linux/string.h>
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/devfs_fs_kernel.h>
#include <linux/smp_lock.h>
#include <asm/uaccess.h>
/*
* 35 has been officially registered as the RAMDISK major number, but
* so is the original MAJOR number of 1. We're using 1 in
* include/linux/major.h for now
*/
#define MAJOR_NR RAMDISK_MAJOR
#include <linux/blk.h>
#include <linux/blkpg.h>
/* The RAM disk size is now a parameter */
#define NUM_RAMDISKS 16 /* This cannot be overridden (yet) */
#ifdef CONFIG_BLK_DEV_INITRD
static int initrd_users;
unsigned long initrd_start, initrd_end;
int initrd_below_start_ok;
#endif
/* Various static variables go here. Most are used only in the RAM disk code.
*/
static unsigned long rd_length[NUM_RAMDISKS]; /* Size of RAM disks in bytes */
static int rd_hardsec[NUM_RAMDISKS]; /* Size of real blocks in bytes */
static int rd_blocksizes[NUM_RAMDISKS]; /* Size of 1024 byte blocks :) */
static int rd_kbsize[NUM_RAMDISKS]; /* Size in blocks of 1024 bytes */
static devfs_handle_t devfs_handle;
static struct block_device *rd_bdev[NUM_RAMDISKS];/* Protected device data */
/*
* Parameters for the boot-loading of the RAM disk. These are set by
* init/main.c (from arguments to the kernel command line) or from the
* architecture-specific setup routine (from the stored boot sector
* information).
*/
int rd_size = CONFIG_BLK_DEV_RAM_SIZE; /* Size of the RAM disks */
/*
* It would be very desirable to have a soft-blocksize (that in the case
* of the ramdisk driver is also the hardblocksize ;) of PAGE_SIZE because
* doing that we'll achieve a far better MM footprint. Using a rd_blocksize of
* BLOCK_SIZE in the worst case we'll make PAGE_SIZE/BLOCK_SIZE buffer-pages
* unfreeable. With a rd_blocksize of PAGE_SIZE instead we are sure that only
* 1 page will be protected. Depending on the size of the ramdisk you
* may want to change the ramdisk blocksize to achieve a better or worse MM
* behaviour. The default is still BLOCK_SIZE (needed by rd_load_image that
* supposes the filesystem in the image uses a BLOCK_SIZE blocksize).
*/
int rd_blocksize = BLOCK_SIZE; /* blocksize of the RAM disks */
/*
* Copyright (C) 2000 Linus Torvalds.
* 2000 Transmeta Corp.
* aops copied from ramfs.
*/
static void ramdisk_updatepage(struct page * page, int need_kmap)
{
if (!Page_Uptodate(page)) {
struct buffer_head *bh = page->buffers;
void * address;
if (need_kmap)
kmap(page);
address = page_address(page);
if (bh) {
struct buffer_head *tmp = bh;
do {
if (!buffer_uptodate(tmp)) {
memset(address, 0, tmp->b_size);
mark_buffer_uptodate(tmp, 1);
}
address += tmp->b_size;
tmp = tmp->b_this_page;
} while (tmp != bh);
} else
memset(address, 0, PAGE_CACHE_SIZE);
if (need_kmap)
kunmap(page);
flush_dcache_page(page);
SetPageUptodate(page);
}
}
static int ramdisk_readpage(struct file *file, struct page * page)
{
ramdisk_updatepage(page, 1);
UnlockPage(page);
return 0;
}
static int ramdisk_prepare_write(struct file *file, struct page *page, unsigned offset, unsigned to)
{
ramdisk_updatepage(page, 0);
SetPageDirty(page);
return 0;
}
static int ramdisk_commit_write(struct file *file, struct page *page, unsigned offset, unsigned to)
{
return 0;
}
static struct address_space_operations ramdisk_aops = {
readpage: ramdisk_readpage,
writepage: fail_writepage,
prepare_write: ramdisk_prepare_write,
commit_write: ramdisk_commit_write,
};
static int rd_blkdev_pagecache_IO(int rw, struct buffer_head * sbh, int minor)
{
struct address_space * mapping;
unsigned long index;
int offset, size, err;
err = 0;
mapping = rd_bdev[minor]->bd_inode->i_mapping;
/* writing a buffer cache not uptodate must not clear it */
if (sbh->b_page->mapping == mapping) {
if (rw == WRITE) {
mark_buffer_uptodate(sbh, 1);
SetPageDirty(sbh->b_page);
}
goto out;
}
index = sbh->b_rsector >> (PAGE_CACHE_SHIFT - 9);
offset = (sbh->b_rsector << 9) & ~PAGE_CACHE_MASK;
size = sbh->b_size;
do {
int count;
struct page * page;
char * src, * dst;
count = PAGE_CACHE_SIZE - offset;
if (count > size)
count = size;
size -= count;
page = grab_cache_page(mapping, index);
if (!page) {
err = -ENOMEM;
goto out;
}
ramdisk_updatepage(page, 1);
index++;
if (rw == READ) {
src = kmap(page);
src += offset;
dst = bh_kmap(sbh);
} else {
dst = kmap(page);
dst += offset;
src = bh_kmap(sbh);
}
offset = 0;
memcpy(dst, src, count);
kunmap(page);
bh_kunmap(sbh);
if (rw == READ) {
flush_dcache_page(sbh->b_page);
} else {
SetPageDirty(page);
}
UnlockPage(page);
__free_page(page);
} while (size);
out:
return err;
}
/*
* Basically, my strategy here is to set up a buffer-head which can't be
* deleted, and make that my Ramdisk. If the request is outside of the
* allocated size, we must get rid of it...
*
* 19-JAN-1998 Richard Gooch <rgooch@atnf.csiro.au> Added devfs support
*
*/
static int rd_make_request(request_queue_t * q, int rw, struct buffer_head *sbh)
{
unsigned int minor;
unsigned long offset, len;
minor = MINOR(sbh->b_rdev);
if (minor >= NUM_RAMDISKS)
goto fail;
offset = sbh->b_rsector << 9;
len = sbh->b_size;
if ((offset + len) > rd_length[minor])
goto fail;
if (rw==READA)
rw=READ;
if ((rw != READ) && (rw != WRITE)) {
printk(KERN_INFO "RAMDISK: bad command: %d\n", rw);
goto fail;
}
if (rd_blkdev_pagecache_IO(rw, sbh, minor))
goto fail;
sbh->b_end_io(sbh,1);
return 0;
fail:
buffer_IO_error(sbh);
return 0;
}
static int rd_ioctl(struct inode *inode, struct file *file, unsigned int cmd, unsigned long arg)
{
int error = -EINVAL;
unsigned int minor;
if (!inode || !inode->i_rdev)
goto out;
minor = MINOR(inode->i_rdev);
switch (cmd) {
case BLKFLSBUF:
if (!capable(CAP_SYS_ADMIN))
return -EACCES;
/* special: we want to release the ramdisk memory,
it's not like with the other blockdevices where
this ioctl only flushes away the buffer cache. */
error = -EBUSY;
down(&inode->i_bdev->bd_sem);
if (inode->i_bdev->bd_openers <= 2) {
truncate_inode_pages(inode->i_mapping, 0);
error = 0;
}
up(&inode->i_bdev->bd_sem);
invalidate_buffers(inode->i_rdev);
break;
case BLKGETSIZE: /* Return device size */
if (!arg)
break;
error = put_user(rd_kbsize[minor] << 1, (unsigned long *) arg);
break;
case BLKGETSIZE64:
error = put_user((u64)rd_kbsize[minor]<<10, (u64*)arg);
break;
case BLKROSET:
case BLKROGET:
case BLKSSZGET:
error = blk_ioctl(inode->i_rdev, cmd, arg);
};
out:
return error;
}
#ifdef CONFIG_BLK_DEV_INITRD
static ssize_t initrd_read(struct file *file, char *buf,
size_t count, loff_t *ppos)
{
loff_t n = *ppos;
unsigned pos = n;
unsigned left = initrd_end - initrd_start;
if (pos != n || pos >= left)
return 0;
left -= pos;
if (count > left) count = left;
if (count == 0) return 0;
if (copy_to_user(buf, (char *)initrd_start + pos, count))
return -EFAULT;
*ppos = pos + count;
return count;
}
static int initrd_release(struct inode *inode,struct file *file)
{
extern void free_initrd_mem(unsigned long, unsigned long);
lock_kernel();
if (!--initrd_users) {
free_initrd_mem(initrd_start, initrd_end);
initrd_start = 0;
}
unlock_kernel();
blkdev_put(inode->i_bdev, BDEV_FILE);
return 0;
}
static struct file_operations initrd_fops = {
read: initrd_read,
release: initrd_release,
};
#endif
static int rd_open(struct inode * inode, struct file * filp)
{
int unit = DEVICE_NR(inode->i_rdev);
#ifdef CONFIG_BLK_DEV_INITRD
if (unit == INITRD_MINOR) {
if (!initrd_start) return -ENODEV;
initrd_users++;
filp->f_op = &initrd_fops;
return 0;
}
#endif
if (unit >= NUM_RAMDISKS)
return -ENXIO;
/*
* Immunize device against invalidate_buffers() and prune_icache().
*/
if (rd_bdev[unit] == NULL) {
rd_bdev[unit] = bdget(kdev_t_to_nr(inode->i_rdev));
rd_bdev[unit]->bd_openers++;
rd_bdev[unit]->bd_inode->i_mapping->a_ops = &ramdisk_aops;
}
return 0;
}
static struct block_device_operations rd_bd_op = {
owner: THIS_MODULE,
open: rd_open,
ioctl: rd_ioctl,
};
/* Before freeing the module, invalidate all of the protected buffers! */
static void __exit rd_cleanup (void)
{
int i;
for (i = 0 ; i < NUM_RAMDISKS; i++) {
struct block_device *bdev = rd_bdev[i];
rd_bdev[i] = NULL;
if (bdev)
blkdev_put(bdev, BDEV_FILE);
destroy_buffers(MKDEV(MAJOR_NR, i));
}
devfs_unregister (devfs_handle);
unregister_blkdev( MAJOR_NR, "ramdisk" );
hardsect_size[MAJOR_NR] = NULL;
blksize_size[MAJOR_NR] = NULL;
blk_size[MAJOR_NR] = NULL;
}
/* This is the registration and initialization section of the RAM disk driver */
static int __init rd_init (void)
{
int i;
if (rd_blocksize > PAGE_SIZE || rd_blocksize < 512 ||
(rd_blocksize & (rd_blocksize-1)))
{
printk("RAMDISK: wrong blocksize %d, reverting to defaults\n",
rd_blocksize);
rd_blocksize = BLOCK_SIZE;
}
if (register_blkdev(MAJOR_NR, "ramdisk", &rd_bd_op)) {
printk("RAMDISK: Could not get major %d", MAJOR_NR);
return -EIO;
}
blk_queue_make_request(BLK_DEFAULT_QUEUE(MAJOR_NR), &rd_make_request);
for (i = 0; i < NUM_RAMDISKS; i++) {
/* rd_size is given in kB */
rd_length[i] = rd_size << 10;
rd_hardsec[i] = rd_blocksize;
rd_blocksizes[i] = rd_blocksize;
rd_kbsize[i] = rd_size;
}
devfs_handle = devfs_mk_dir (NULL, "rd", NULL);
devfs_register_series (devfs_handle, "%u", NUM_RAMDISKS,
DEVFS_FL_DEFAULT, MAJOR_NR, 0,
S_IFBLK | S_IRUSR | S_IWUSR,
&rd_bd_op, NULL);
for (i = 0; i < NUM_RAMDISKS; i++)
register_disk(NULL, MKDEV(MAJOR_NR,i), 1, &rd_bd_op, rd_size<<1);
#ifdef CONFIG_BLK_DEV_INITRD
/* We ought to separate initrd operations here */
register_disk(NULL, MKDEV(MAJOR_NR,INITRD_MINOR), 1, &rd_bd_op, rd_size<<1);
devfs_register(devfs_handle, "initrd", DEVFS_FL_DEFAULT, MAJOR_NR,
INITRD_MINOR, S_IFBLK | S_IRUSR, &rd_bd_op, NULL);
#endif
hardsect_size[MAJOR_NR] = rd_hardsec; /* Size of the RAM disk blocks */
blksize_size[MAJOR_NR] = rd_blocksizes; /* Avoid set_blocksize() check */
blk_size[MAJOR_NR] = rd_kbsize; /* Size of the RAM disk in kB */
/* rd_size is given in kB */
printk("RAMDISK driver initialized: "
"%d RAM disks of %dK size %d blocksize\n",
NUM_RAMDISKS, rd_size, rd_blocksize);
return 0;
}
module_init(rd_init);
module_exit(rd_cleanup);
/* options - nonmodular */
#ifndef MODULE
static int __init ramdisk_size(char *str)
{
rd_size = simple_strtol(str,NULL,0);
return 1;
}
static int __init ramdisk_size2(char *str) /* kludge */
{
return ramdisk_size(str);
}
static int __init ramdisk_blocksize(char *str)
{
rd_blocksize = simple_strtol(str,NULL,0);
return 1;
}
__setup("ramdisk=", ramdisk_size);
__setup("ramdisk_size=", ramdisk_size2);
__setup("ramdisk_blocksize=", ramdisk_blocksize);
#endif
/* options - modular */
MODULE_PARM (rd_size, "1i");
MODULE_PARM_DESC(rd_size, "Size of each RAM disk in kbytes.");
MODULE_PARM (rd_blocksize, "i");
MODULE_PARM_DESC(rd_blocksize, "Blocksize of each RAM disk in bytes.");
MODULE_LICENSE("GPL");