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127 lines
2.7 KiB
127 lines
2.7 KiB
2 years ago
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/*
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* linux/kernel/blk_drv/ramdisk.c
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*
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* Written by Theodore Ts'o, 12/2/91
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*/
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#include <string.h>
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#include <linux/config.h>
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#include <linux/sched.h>
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#include <linux/fs.h>
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#include <linux/kernel.h>
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#include <asm/system.h>
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#include <asm/segment.h>
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#include <asm/memory.h>
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#define MAJOR_NR 1
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#include "blk.h"
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char *rd_start;
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int rd_length = 0;
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void do_rd_request(void)
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{
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int len;
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char *addr;
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INIT_REQUEST;
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addr = rd_start + (CURRENT->sector << 9);
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len = CURRENT->nr_sectors << 9;
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if ((MINOR(CURRENT->dev) != 1) || (addr+len > rd_start+rd_length)) {
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end_request(0);
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goto repeat;
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}
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if (CURRENT-> cmd == WRITE) {
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(void ) memcpy(addr,
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CURRENT->buffer,
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len);
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} else if (CURRENT->cmd == READ) {
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(void) memcpy(CURRENT->buffer,
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addr,
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len);
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} else
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panic("unknown ramdisk-command");
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end_request(1);
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goto repeat;
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}
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/*
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* Returns amount of memory which needs to be reserved.
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*/
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long rd_init(long mem_start, int length)
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{
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int i;
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char *cp;
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blk_dev[MAJOR_NR].request_fn = DEVICE_REQUEST;
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rd_start = (char *) mem_start;
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rd_length = length;
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cp = rd_start;
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for (i=0; i < length; i++)
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*cp++ = '\0';
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return(length);
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}
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/*
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* If the root device is the ram disk, try to load it.
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* In order to do this, the root device is originally set to the
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* floppy, and we later change it to be ram disk.
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*/
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void rd_load(void)
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{
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struct buffer_head *bh;
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struct super_block s;
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int block = 256; /* Start at block 256 */
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int i = 1;
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int nblocks;
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char *cp; /* Move pointer */
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if (!rd_length)
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return;
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printk("Ram disk: %d bytes, starting at 0x%x\n", rd_length,
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(int) rd_start);
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if (MAJOR(ROOT_DEV) != 2)
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return;
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bh = breada(ROOT_DEV,block+1,block,block+2,-1);
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if (!bh) {
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printk("Disk error while looking for ramdisk!\n");
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return;
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}
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__asm__ volatile ("cld"); /* by wyj */
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*((struct d_super_block *) &s) = *((struct d_super_block *) bh->b_data);
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brelse(bh);
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if (s.s_magic != SUPER_MAGIC)
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/* No ram disk image present, assume normal floppy boot */
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return;
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nblocks = s.s_nzones << s.s_log_zone_size;
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if (nblocks > (rd_length >> BLOCK_SIZE_BITS)) {
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printk("Ram disk image too big! (%d blocks, %d avail)\n",
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nblocks, rd_length >> BLOCK_SIZE_BITS);
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return;
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}
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printk("Loading %d bytes into ram disk... 0000k",
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nblocks << BLOCK_SIZE_BITS);
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cp = rd_start;
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while (nblocks) {
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if (nblocks > 2)
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bh = breada(ROOT_DEV, block, block+1, block+2, -1);
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else
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bh = bread(ROOT_DEV, block);
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if (!bh) {
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printk("I/O error on block %d, aborting load\n",
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block);
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return;
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}
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(void) memcpy(cp, bh->b_data, BLOCK_SIZE);
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brelse(bh);
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printk("\010\010\010\010\010%4dk",i);
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cp += BLOCK_SIZE;
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block++;
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nblocks--;
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i++;
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}
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printk("\010\010\010\010\010done \n");
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ROOT_DEV=0x0101;
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}
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