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/*
* linux/kernel/blk_drv/ramdisk.c
*
* Written by Theodore Ts'o, 12/2/91
*
* Modifications by Fred N. van Kempen to allow for bootable root
* disks (which are used in LINUX/Pro). Also some cleanups. 03/03/93
*/
#include <linux/config.h>
#include <linux/sched.h>
#include <linux/minix_fs.h>
#include <linux/ext2_fs.h>
#include <linux/fs.h>
#include <linux/kernel.h>
#include <linux/string.h>
#include <asm/system.h>
#include <asm/segment.h>
#define MAJOR_NR MEM_MAJOR
#include "blk.h"
#define RAMDISK_MINOR 1
extern void wait_for_keypress(void);
char *rd_start;
int rd_length = 0;
static int rd_blocksizes[2] = {0, 0};
static void do_rd_request(void)
{
int len;
char *addr;
repeat:
INIT_REQUEST;
addr = rd_start + (CURRENT->sector << 9);
len = CURRENT->current_nr_sectors << 9;
if ((MINOR(CURRENT->dev) != RAMDISK_MINOR) ||
(addr+len > rd_start+rd_length)) {
end_request(0);
goto repeat;
}
if (CURRENT-> cmd == WRITE) {
(void ) memcpy(addr,
CURRENT->buffer,
len);
} else if (CURRENT->cmd == READ) {
(void) memcpy(CURRENT->buffer,
addr,
len);
} else
panic("RAMDISK: unknown RAM disk command !\n");
end_request(1);
goto repeat;
}
static struct file_operations rd_fops = {
NULL, /* lseek - default */
block_read, /* read - general block-dev read */
block_write, /* write - general block-dev write */
NULL, /* readdir - bad */
NULL, /* select */
NULL, /* ioctl */
NULL, /* mmap */
NULL, /* no special open code */
NULL, /* no special release code */
block_fsync /* fsync */
};
/*
* Returns amount of memory which needs to be reserved.
*/
long rd_init(long mem_start, int length)
{
int i;
char *cp;
if (register_blkdev(MEM_MAJOR,"rd",&rd_fops)) {
printk("RAMDISK: Unable to get major %d.\n", MEM_MAJOR);
return 0;
}
blk_dev[MEM_MAJOR].request_fn = DEVICE_REQUEST;
rd_start = (char *) mem_start;
rd_length = length;
cp = rd_start;
for (i=0; i < length; i++)
*cp++ = '\0';
for(i=0;i<2;i++) rd_blocksizes[i] = 1024;
blksize_size[MAJOR_NR] = rd_blocksizes;
return(length);
}
static void do_load(void)
{
struct buffer_head *bh;
struct super_block {
union
{
char minix [sizeof (struct minix_super_block)];
char ext2 [sizeof (struct ext2_super_block)];
} record;
} sb;
struct minix_super_block *minixsb =
(struct minix_super_block *)&sb;
struct ext2_super_block *ext2sb =
(struct ext2_super_block *)&sb;
int block, tries;
int i = 1;
int nblocks;
char *cp;
/*
* Check for a super block on the diskette.
* The old-style boot/root diskettes had their RAM image
* starting at block 512 of the boot diskette. LINUX/Pro
* uses the entire diskette as a file system, so in that
* case, we have to look at block 0. Be intelligent about
* this, and check both... - FvK
*/
for (tries = 0; tries < 1000; tries += 512) {
block = tries;
bh = breada(ROOT_DEV,block+1,BLOCK_SIZE, 0, PAGE_SIZE);
if (!bh) {
printk("RAMDISK: I/O error while looking for super block!\n");
return;
}
/* This is silly- why do we require it to be a MINIX FS? */
*((struct super_block *) &sb) =
*((struct super_block *) bh->b_data);
brelse(bh);
/* Try Minix */
nblocks = -1;
if (minixsb->s_magic == MINIX_SUPER_MAGIC ||
minixsb->s_magic == MINIX_SUPER_MAGIC2) {
printk("RAMDISK: Minix filesystem found at block %d\n",
block);
nblocks = minixsb->s_nzones << minixsb->s_log_zone_size;
}
/* Try ext2 */
if (nblocks == -1 && (ext2sb->s_magic ==
EXT2_PRE_02B_MAGIC ||
ext2sb->s_magic == EXT2_SUPER_MAGIC))
{
printk("RAMDISK: Ext2 filesystem found at block %d\n",
block);
nblocks = ext2sb->s_blocks_count;
}
if (nblocks == -1)
{
printk("RAMDISK: trying old-style RAM image.\n");
continue;
}
if (nblocks > (rd_length >> BLOCK_SIZE_BITS)) {
printk("RAMDISK: image too big! (%d/%d blocks)\n",
nblocks, rd_length >> BLOCK_SIZE_BITS);
return;
}
printk("RAMDISK: Loading %d blocks into RAM disk", nblocks);
/* We found an image file system. Load it into core! */
cp = rd_start;
while (nblocks) {
if (nblocks > 2)
bh = breada(ROOT_DEV, block, BLOCK_SIZE, 0, PAGE_SIZE);
else
bh = bread(ROOT_DEV, block, BLOCK_SIZE);
if (!bh) {
printk("RAMDISK: I/O error on block %d, aborting!\n",
block);
return;
}
(void) memcpy(cp, bh->b_data, BLOCK_SIZE);
brelse(bh);
if (!(nblocks-- & 15)) printk(".");
cp += BLOCK_SIZE;
block++;
i++;
}
printk("\ndone\n");
/* We loaded the file system image. Prepare for mounting it. */
ROOT_DEV = ((MEM_MAJOR << 8) | RAMDISK_MINOR);
return;
}
}
/*
* If the root device is the RAM disk, try to load it.
* In order to do this, the root device is originally set to the
* floppy, and we later change it to be RAM disk.
*/
void rd_load(void)
{
struct inode inode;
struct file filp;
/* If no RAM disk specified, give up early. */
if (!rd_length)
return;
printk("RAMDISK: %d bytes, starting at 0x%x\n",
rd_length, (int) rd_start);
/* If we are doing a diskette boot, we might have to pre-load it. */
if (MAJOR(ROOT_DEV) != FLOPPY_MAJOR)
return;
/* for Slackware install disks */
printk(KERN_NOTICE "VFS: Insert ramdisk floppy and press ENTER\n");
wait_for_keypress();
memset(&filp, 0, sizeof(filp));
memset(&inode, 0, sizeof(inode));
inode.i_rdev = ROOT_DEV;
filp.f_mode = 1; /* read only */
filp.f_inode = &inode;
if(blkdev_open(&inode, &filp) == 0 ){
do_load();
if(filp.f_op && filp.f_op->release)
filp.f_op->release(&inode,&filp);
}
}
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