linux/init/do_mounts_rd.c
<<
>>
Prefs
   1
   2#include <linux/kernel.h>
   3#include <linux/fs.h>
   4#include <linux/minix_fs.h>
   5#include <linux/ext2_fs.h>
   6#include <linux/romfs_fs.h>
   7#include <linux/cramfs_fs.h>
   8#include <linux/initrd.h>
   9#include <linux/string.h>
  10#include <linux/slab.h>
  11
  12#include "do_mounts.h"
  13#include "../fs/squashfs/squashfs_fs.h"
  14
  15#include <linux/decompress/generic.h>
  16
  17
  18int __initdata rd_prompt = 1;/* 1 = prompt for RAM disk, 0 = don't prompt */
  19
  20static int __init prompt_ramdisk(char *str)
  21{
  22        rd_prompt = simple_strtol(str,NULL,0) & 1;
  23        return 1;
  24}
  25__setup("prompt_ramdisk=", prompt_ramdisk);
  26
  27int __initdata rd_image_start;          /* starting block # of image */
  28
  29static int __init ramdisk_start_setup(char *str)
  30{
  31        rd_image_start = simple_strtol(str,NULL,0);
  32        return 1;
  33}
  34__setup("ramdisk_start=", ramdisk_start_setup);
  35
  36static int __init crd_load(int in_fd, int out_fd, decompress_fn deco);
  37
  38/*
  39 * This routine tries to find a RAM disk image to load, and returns the
  40 * number of blocks to read for a non-compressed image, 0 if the image
  41 * is a compressed image, and -1 if an image with the right magic
  42 * numbers could not be found.
  43 *
  44 * We currently check for the following magic numbers:
  45 *      minix
  46 *      ext2
  47 *      romfs
  48 *      cramfs
  49 *      squashfs
  50 *      gzip
  51 */
  52static int __init
  53identify_ramdisk_image(int fd, int start_block, decompress_fn *decompressor)
  54{
  55        const int size = 512;
  56        struct minix_super_block *minixsb;
  57        struct ext2_super_block *ext2sb;
  58        struct romfs_super_block *romfsb;
  59        struct cramfs_super *cramfsb;
  60        struct squashfs_super_block *squashfsb;
  61        int nblocks = -1;
  62        unsigned char *buf;
  63        const char *compress_name;
  64
  65        buf = kmalloc(size, GFP_KERNEL);
  66        if (!buf)
  67                return -ENOMEM;
  68
  69        minixsb = (struct minix_super_block *) buf;
  70        ext2sb = (struct ext2_super_block *) buf;
  71        romfsb = (struct romfs_super_block *) buf;
  72        cramfsb = (struct cramfs_super *) buf;
  73        squashfsb = (struct squashfs_super_block *) buf;
  74        memset(buf, 0xe5, size);
  75
  76        /*
  77         * Read block 0 to test for compressed kernel
  78         */
  79        sys_lseek(fd, start_block * BLOCK_SIZE, 0);
  80        sys_read(fd, buf, size);
  81
  82        *decompressor = decompress_method(buf, size, &compress_name);
  83        if (compress_name) {
  84                printk(KERN_NOTICE "RAMDISK: %s image found at block %d\n",
  85                       compress_name, start_block);
  86                if (!*decompressor)
  87                        printk(KERN_EMERG
  88                               "RAMDISK: %s decompressor not configured!\n",
  89                               compress_name);
  90                nblocks = 0;
  91                goto done;
  92        }
  93
  94        /* romfs is at block zero too */
  95        if (romfsb->word0 == ROMSB_WORD0 &&
  96            romfsb->word1 == ROMSB_WORD1) {
  97                printk(KERN_NOTICE
  98                       "RAMDISK: romfs filesystem found at block %d\n",
  99                       start_block);
 100                nblocks = (ntohl(romfsb->size)+BLOCK_SIZE-1)>>BLOCK_SIZE_BITS;
 101                goto done;
 102        }
 103
 104        if (cramfsb->magic == CRAMFS_MAGIC) {
 105                printk(KERN_NOTICE
 106                       "RAMDISK: cramfs filesystem found at block %d\n",
 107                       start_block);
 108                nblocks = (cramfsb->size + BLOCK_SIZE - 1) >> BLOCK_SIZE_BITS;
 109                goto done;
 110        }
 111
 112        /* squashfs is at block zero too */
 113        if (le32_to_cpu(squashfsb->s_magic) == SQUASHFS_MAGIC) {
 114                printk(KERN_NOTICE
 115                       "RAMDISK: squashfs filesystem found at block %d\n",
 116                       start_block);
 117                nblocks = (le64_to_cpu(squashfsb->bytes_used) + BLOCK_SIZE - 1)
 118                         >> BLOCK_SIZE_BITS;
 119                goto done;
 120        }
 121
 122        /*
 123         * Read block 1 to test for minix and ext2 superblock
 124         */
 125        sys_lseek(fd, (start_block+1) * BLOCK_SIZE, 0);
 126        sys_read(fd, buf, size);
 127
 128        /* Try minix */
 129        if (minixsb->s_magic == MINIX_SUPER_MAGIC ||
 130            minixsb->s_magic == MINIX_SUPER_MAGIC2) {
 131                printk(KERN_NOTICE
 132                       "RAMDISK: Minix filesystem found at block %d\n",
 133                       start_block);
 134                nblocks = minixsb->s_nzones << minixsb->s_log_zone_size;
 135                goto done;
 136        }
 137
 138        /* Try ext2 */
 139        if (ext2sb->s_magic == cpu_to_le16(EXT2_SUPER_MAGIC)) {
 140                printk(KERN_NOTICE
 141                       "RAMDISK: ext2 filesystem found at block %d\n",
 142                       start_block);
 143                nblocks = le32_to_cpu(ext2sb->s_blocks_count) <<
 144                        le32_to_cpu(ext2sb->s_log_block_size);
 145                goto done;
 146        }
 147
 148        printk(KERN_NOTICE
 149               "RAMDISK: Couldn't find valid RAM disk image starting at %d.\n",
 150               start_block);
 151
 152done:
 153        sys_lseek(fd, start_block * BLOCK_SIZE, 0);
 154        kfree(buf);
 155        return nblocks;
 156}
 157
 158int __init rd_load_image(char *from)
 159{
 160        int res = 0;
 161        int in_fd, out_fd;
 162        unsigned long rd_blocks, devblocks;
 163        int nblocks, i, disk;
 164        char *buf = NULL;
 165        unsigned short rotate = 0;
 166        decompress_fn decompressor = NULL;
 167#if !defined(CONFIG_S390) && !defined(CONFIG_PPC_ISERIES)
 168        char rotator[4] = { '|' , '/' , '-' , '\\' };
 169#endif
 170
 171        out_fd = sys_open((const char __user __force *) "/dev/ram", O_RDWR, 0);
 172        if (out_fd < 0)
 173                goto out;
 174
 175        in_fd = sys_open(from, O_RDONLY, 0);
 176        if (in_fd < 0)
 177                goto noclose_input;
 178
 179        nblocks = identify_ramdisk_image(in_fd, rd_image_start, &decompressor);
 180        if (nblocks < 0)
 181                goto done;
 182
 183        if (nblocks == 0) {
 184                if (crd_load(in_fd, out_fd, decompressor) == 0)
 185                        goto successful_load;
 186                goto done;
 187        }
 188
 189        /*
 190         * NOTE NOTE: nblocks is not actually blocks but
 191         * the number of kibibytes of data to load into a ramdisk.
 192         * So any ramdisk block size that is a multiple of 1KiB should
 193         * work when the appropriate ramdisk_blocksize is specified
 194         * on the command line.
 195         *
 196         * The default ramdisk_blocksize is 1KiB and it is generally
 197         * silly to use anything else, so make sure to use 1KiB
 198         * blocksize while generating ext2fs ramdisk-images.
 199         */
 200        if (sys_ioctl(out_fd, BLKGETSIZE, (unsigned long)&rd_blocks) < 0)
 201                rd_blocks = 0;
 202        else
 203                rd_blocks >>= 1;
 204
 205        if (nblocks > rd_blocks) {
 206                printk("RAMDISK: image too big! (%dKiB/%ldKiB)\n",
 207                       nblocks, rd_blocks);
 208                goto done;
 209        }
 210
 211        /*
 212         * OK, time to copy in the data
 213         */
 214        if (sys_ioctl(in_fd, BLKGETSIZE, (unsigned long)&devblocks) < 0)
 215                devblocks = 0;
 216        else
 217                devblocks >>= 1;
 218
 219        if (strcmp(from, "/initrd.image") == 0)
 220                devblocks = nblocks;
 221
 222        if (devblocks == 0) {
 223                printk(KERN_ERR "RAMDISK: could not determine device size\n");
 224                goto done;
 225        }
 226
 227        buf = kmalloc(BLOCK_SIZE, GFP_KERNEL);
 228        if (!buf) {
 229                printk(KERN_ERR "RAMDISK: could not allocate buffer\n");
 230                goto done;
 231        }
 232
 233        printk(KERN_NOTICE "RAMDISK: Loading %dKiB [%ld disk%s] into ram disk... ",
 234                nblocks, ((nblocks-1)/devblocks)+1, nblocks>devblocks ? "s" : "");
 235        for (i = 0, disk = 1; i < nblocks; i++) {
 236                if (i && (i % devblocks == 0)) {
 237                        printk("done disk #%d.\n", disk++);
 238                        rotate = 0;
 239                        if (sys_close(in_fd)) {
 240                                printk("Error closing the disk.\n");
 241                                goto noclose_input;
 242                        }
 243                        change_floppy("disk #%d", disk);
 244                        in_fd = sys_open(from, O_RDONLY, 0);
 245                        if (in_fd < 0)  {
 246                                printk("Error opening disk.\n");
 247                                goto noclose_input;
 248                        }
 249                        printk("Loading disk #%d... ", disk);
 250                }
 251                sys_read(in_fd, buf, BLOCK_SIZE);
 252                sys_write(out_fd, buf, BLOCK_SIZE);
 253#if !defined(CONFIG_S390) && !defined(CONFIG_PPC_ISERIES)
 254                if (!(i % 16)) {
 255                        printk("%c\b", rotator[rotate & 0x3]);
 256                        rotate++;
 257                }
 258#endif
 259        }
 260        printk("done.\n");
 261
 262successful_load:
 263        res = 1;
 264done:
 265        sys_close(in_fd);
 266noclose_input:
 267        sys_close(out_fd);
 268out:
 269        kfree(buf);
 270        sys_unlink((const char __user __force *) "/dev/ram");
 271        return res;
 272}
 273
 274int __init rd_load_disk(int n)
 275{
 276        if (rd_prompt)
 277                change_floppy("root floppy disk to be loaded into RAM disk");
 278        create_dev("/dev/root", ROOT_DEV);
 279        create_dev("/dev/ram", MKDEV(RAMDISK_MAJOR, n));
 280        return rd_load_image("/dev/root");
 281}
 282
 283static int exit_code;
 284static int decompress_error;
 285static int crd_infd, crd_outfd;
 286
 287static int __init compr_fill(void *buf, unsigned int len)
 288{
 289        int r = sys_read(crd_infd, buf, len);
 290        if (r < 0)
 291                printk(KERN_ERR "RAMDISK: error while reading compressed data");
 292        else if (r == 0)
 293                printk(KERN_ERR "RAMDISK: EOF while reading compressed data");
 294        return r;
 295}
 296
 297static int __init compr_flush(void *window, unsigned int outcnt)
 298{
 299        int written = sys_write(crd_outfd, window, outcnt);
 300        if (written != outcnt) {
 301                if (decompress_error == 0)
 302                        printk(KERN_ERR
 303                               "RAMDISK: incomplete write (%d != %d)\n",
 304                               written, outcnt);
 305                decompress_error = 1;
 306                return -1;
 307        }
 308        return outcnt;
 309}
 310
 311static void __init error(char *x)
 312{
 313        printk(KERN_ERR "%s\n", x);
 314        exit_code = 1;
 315        decompress_error = 1;
 316}
 317
 318static int __init crd_load(int in_fd, int out_fd, decompress_fn deco)
 319{
 320        int result;
 321        crd_infd = in_fd;
 322        crd_outfd = out_fd;
 323        result = deco(NULL, 0, compr_fill, compr_flush, NULL, NULL, error);
 324        if (decompress_error)
 325                result = 1;
 326        return result;
 327}
 328
lxr.linux.no kindly hosted by Redpill Linpro AS, provider of Linux consulting and operations services since 1995.