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https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-08-24 09:50:04 +00:00
![Pierre Ossman](/assets/img/avatar_default.png)
Some buses (e.g. USB and MMC) do their scanning of devices in the background, causing a race between them and prepare_namespace(). In order to be able to use these buses without an initrd, we now wait for the device specified in root= to actually show up. If the device never shows up than we will hang in an infinite loop. In order to not mess with setups that reboot on panic, the feature must be turned on via the command line option "rootwait". [bunk@stusta.de: root_wait can become static] Signed-off-by: Pierre Ossman <drzeus@drzeus.cx> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Christoph Hellwig <hch@lst.de> Signed-off-by: Adrian Bunk <bunk@stusta.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
475 lines
10 KiB
C
475 lines
10 KiB
C
#include <linux/module.h>
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#include <linux/sched.h>
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#include <linux/ctype.h>
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#include <linux/fd.h>
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#include <linux/tty.h>
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#include <linux/suspend.h>
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#include <linux/root_dev.h>
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#include <linux/security.h>
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#include <linux/delay.h>
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#include <linux/genhd.h>
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#include <linux/mount.h>
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#include <linux/device.h>
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#include <linux/init.h>
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#include <linux/nfs_fs.h>
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#include <linux/nfs_fs_sb.h>
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#include <linux/nfs_mount.h>
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#include "do_mounts.h"
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extern int get_filesystem_list(char * buf);
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int __initdata rd_doload; /* 1 = load RAM disk, 0 = don't load */
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int root_mountflags = MS_RDONLY | MS_SILENT;
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char * __initdata root_device_name;
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static char __initdata saved_root_name[64];
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static int __initdata root_wait;
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dev_t ROOT_DEV;
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static int __init load_ramdisk(char *str)
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{
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rd_doload = simple_strtol(str,NULL,0) & 3;
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return 1;
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}
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__setup("load_ramdisk=", load_ramdisk);
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static int __init readonly(char *str)
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{
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if (*str)
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return 0;
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root_mountflags |= MS_RDONLY;
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return 1;
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}
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static int __init readwrite(char *str)
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{
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if (*str)
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return 0;
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root_mountflags &= ~MS_RDONLY;
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return 1;
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}
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__setup("ro", readonly);
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__setup("rw", readwrite);
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static dev_t try_name(char *name, int part)
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{
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char path[64];
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char buf[32];
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int range;
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dev_t res;
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char *s;
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int len;
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int fd;
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unsigned int maj, min;
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/* read device number from .../dev */
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sprintf(path, "/sys/block/%s/dev", name);
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fd = sys_open(path, 0, 0);
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if (fd < 0)
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goto fail;
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len = sys_read(fd, buf, 32);
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sys_close(fd);
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if (len <= 0 || len == 32 || buf[len - 1] != '\n')
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goto fail;
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buf[len - 1] = '\0';
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if (sscanf(buf, "%u:%u", &maj, &min) == 2) {
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/*
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* Try the %u:%u format -- see print_dev_t()
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*/
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res = MKDEV(maj, min);
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if (maj != MAJOR(res) || min != MINOR(res))
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goto fail;
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} else {
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/*
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* Nope. Try old-style "0321"
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*/
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res = new_decode_dev(simple_strtoul(buf, &s, 16));
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if (*s)
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goto fail;
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}
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/* if it's there and we are not looking for a partition - that's it */
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if (!part)
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return res;
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/* otherwise read range from .../range */
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sprintf(path, "/sys/block/%s/range", name);
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fd = sys_open(path, 0, 0);
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if (fd < 0)
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goto fail;
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len = sys_read(fd, buf, 32);
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sys_close(fd);
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if (len <= 0 || len == 32 || buf[len - 1] != '\n')
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goto fail;
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buf[len - 1] = '\0';
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range = simple_strtoul(buf, &s, 10);
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if (*s)
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goto fail;
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/* if partition is within range - we got it */
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if (part < range)
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return res + part;
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fail:
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return 0;
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}
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/*
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* Convert a name into device number. We accept the following variants:
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*
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* 1) device number in hexadecimal represents itself
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* 2) /dev/nfs represents Root_NFS (0xff)
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* 3) /dev/<disk_name> represents the device number of disk
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* 4) /dev/<disk_name><decimal> represents the device number
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* of partition - device number of disk plus the partition number
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* 5) /dev/<disk_name>p<decimal> - same as the above, that form is
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* used when disk name of partitioned disk ends on a digit.
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*
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* If name doesn't have fall into the categories above, we return 0.
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* Sysfs is used to check if something is a disk name - it has
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* all known disks under bus/block/devices. If the disk name
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* contains slashes, name of sysfs node has them replaced with
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* bangs. try_name() does the actual checks, assuming that sysfs
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* is mounted on rootfs /sys.
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*/
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dev_t name_to_dev_t(char *name)
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{
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char s[32];
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char *p;
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dev_t res = 0;
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int part;
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#ifdef CONFIG_SYSFS
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int mkdir_err = sys_mkdir("/sys", 0700);
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if (sys_mount("sysfs", "/sys", "sysfs", 0, NULL) < 0)
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goto out;
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#endif
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if (strncmp(name, "/dev/", 5) != 0) {
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unsigned maj, min;
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if (sscanf(name, "%u:%u", &maj, &min) == 2) {
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res = MKDEV(maj, min);
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if (maj != MAJOR(res) || min != MINOR(res))
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goto fail;
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} else {
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res = new_decode_dev(simple_strtoul(name, &p, 16));
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if (*p)
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goto fail;
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}
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goto done;
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}
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name += 5;
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res = Root_NFS;
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if (strcmp(name, "nfs") == 0)
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goto done;
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res = Root_RAM0;
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if (strcmp(name, "ram") == 0)
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goto done;
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if (strlen(name) > 31)
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goto fail;
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strcpy(s, name);
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for (p = s; *p; p++)
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if (*p == '/')
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*p = '!';
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res = try_name(s, 0);
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if (res)
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goto done;
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while (p > s && isdigit(p[-1]))
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p--;
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if (p == s || !*p || *p == '0')
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goto fail;
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part = simple_strtoul(p, NULL, 10);
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*p = '\0';
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res = try_name(s, part);
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if (res)
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goto done;
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if (p < s + 2 || !isdigit(p[-2]) || p[-1] != 'p')
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goto fail;
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p[-1] = '\0';
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res = try_name(s, part);
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done:
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#ifdef CONFIG_SYSFS
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sys_umount("/sys", 0);
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out:
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if (!mkdir_err)
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sys_rmdir("/sys");
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#endif
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return res;
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fail:
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res = 0;
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goto done;
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}
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static int __init root_dev_setup(char *line)
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{
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strlcpy(saved_root_name, line, sizeof(saved_root_name));
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return 1;
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}
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__setup("root=", root_dev_setup);
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static int __init rootwait_setup(char *str)
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{
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if (*str)
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return 0;
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root_wait = 1;
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return 1;
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}
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__setup("rootwait", rootwait_setup);
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static char * __initdata root_mount_data;
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static int __init root_data_setup(char *str)
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{
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root_mount_data = str;
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return 1;
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}
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static char * __initdata root_fs_names;
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static int __init fs_names_setup(char *str)
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{
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root_fs_names = str;
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return 1;
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}
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static unsigned int __initdata root_delay;
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static int __init root_delay_setup(char *str)
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{
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root_delay = simple_strtoul(str, NULL, 0);
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return 1;
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}
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__setup("rootflags=", root_data_setup);
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__setup("rootfstype=", fs_names_setup);
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__setup("rootdelay=", root_delay_setup);
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static void __init get_fs_names(char *page)
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{
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char *s = page;
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if (root_fs_names) {
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strcpy(page, root_fs_names);
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while (*s++) {
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if (s[-1] == ',')
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s[-1] = '\0';
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}
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} else {
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int len = get_filesystem_list(page);
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char *p, *next;
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page[len] = '\0';
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for (p = page-1; p; p = next) {
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next = strchr(++p, '\n');
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if (*p++ != '\t')
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continue;
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while ((*s++ = *p++) != '\n')
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;
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s[-1] = '\0';
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}
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}
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*s = '\0';
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}
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static int __init do_mount_root(char *name, char *fs, int flags, void *data)
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{
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int err = sys_mount(name, "/root", fs, flags, data);
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if (err)
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return err;
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sys_chdir("/root");
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ROOT_DEV = current->fs->pwdmnt->mnt_sb->s_dev;
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printk("VFS: Mounted root (%s filesystem)%s.\n",
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current->fs->pwdmnt->mnt_sb->s_type->name,
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current->fs->pwdmnt->mnt_sb->s_flags & MS_RDONLY ?
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" readonly" : "");
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return 0;
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}
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void __init mount_block_root(char *name, int flags)
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{
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char *fs_names = __getname();
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char *p;
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#ifdef CONFIG_BLOCK
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char b[BDEVNAME_SIZE];
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#else
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const char *b = name;
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#endif
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get_fs_names(fs_names);
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retry:
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for (p = fs_names; *p; p += strlen(p)+1) {
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int err = do_mount_root(name, p, flags, root_mount_data);
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switch (err) {
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case 0:
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goto out;
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case -EACCES:
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flags |= MS_RDONLY;
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goto retry;
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case -EINVAL:
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continue;
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}
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/*
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* Allow the user to distinguish between failed sys_open
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* and bad superblock on root device.
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* and give them a list of the available devices
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*/
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#ifdef CONFIG_BLOCK
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__bdevname(ROOT_DEV, b);
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#endif
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printk("VFS: Cannot open root device \"%s\" or %s\n",
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root_device_name, b);
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printk("Please append a correct \"root=\" boot option; here are the available partitions:\n");
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printk_all_partitions();
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panic("VFS: Unable to mount root fs on %s", b);
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}
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printk("List of all partitions:\n");
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printk_all_partitions();
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printk("No filesystem could mount root, tried: ");
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for (p = fs_names; *p; p += strlen(p)+1)
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printk(" %s", p);
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printk("\n");
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#ifdef CONFIG_BLOCK
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__bdevname(ROOT_DEV, b);
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#endif
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panic("VFS: Unable to mount root fs on %s", b);
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out:
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putname(fs_names);
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}
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#ifdef CONFIG_ROOT_NFS
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static int __init mount_nfs_root(void)
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{
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void *data = nfs_root_data();
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create_dev("/dev/root", ROOT_DEV);
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if (data &&
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do_mount_root("/dev/root", "nfs", root_mountflags, data) == 0)
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return 1;
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return 0;
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}
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#endif
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#if defined(CONFIG_BLK_DEV_RAM) || defined(CONFIG_BLK_DEV_FD)
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void __init change_floppy(char *fmt, ...)
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{
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struct termios termios;
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char buf[80];
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char c;
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int fd;
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va_list args;
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va_start(args, fmt);
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vsprintf(buf, fmt, args);
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va_end(args);
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fd = sys_open("/dev/root", O_RDWR | O_NDELAY, 0);
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if (fd >= 0) {
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sys_ioctl(fd, FDEJECT, 0);
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sys_close(fd);
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}
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printk(KERN_NOTICE "VFS: Insert %s and press ENTER\n", buf);
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fd = sys_open("/dev/console", O_RDWR, 0);
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if (fd >= 0) {
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sys_ioctl(fd, TCGETS, (long)&termios);
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termios.c_lflag &= ~ICANON;
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sys_ioctl(fd, TCSETSF, (long)&termios);
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sys_read(fd, &c, 1);
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termios.c_lflag |= ICANON;
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sys_ioctl(fd, TCSETSF, (long)&termios);
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sys_close(fd);
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}
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}
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#endif
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void __init mount_root(void)
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{
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#ifdef CONFIG_ROOT_NFS
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if (MAJOR(ROOT_DEV) == UNNAMED_MAJOR) {
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if (mount_nfs_root())
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return;
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printk(KERN_ERR "VFS: Unable to mount root fs via NFS, trying floppy.\n");
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ROOT_DEV = Root_FD0;
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}
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#endif
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#ifdef CONFIG_BLK_DEV_FD
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if (MAJOR(ROOT_DEV) == FLOPPY_MAJOR) {
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/* rd_doload is 2 for a dual initrd/ramload setup */
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if (rd_doload==2) {
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if (rd_load_disk(1)) {
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ROOT_DEV = Root_RAM1;
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root_device_name = NULL;
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}
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} else
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change_floppy("root floppy");
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}
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#endif
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#ifdef CONFIG_BLOCK
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create_dev("/dev/root", ROOT_DEV);
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mount_block_root("/dev/root", root_mountflags);
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#endif
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}
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/*
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* Prepare the namespace - decide what/where to mount, load ramdisks, etc.
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*/
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void __init prepare_namespace(void)
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{
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int is_floppy;
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if (root_delay) {
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printk(KERN_INFO "Waiting %dsec before mounting root device...\n",
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root_delay);
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ssleep(root_delay);
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}
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/* wait for the known devices to complete their probing */
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while (driver_probe_done() != 0)
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msleep(100);
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md_run_setup();
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if (saved_root_name[0]) {
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root_device_name = saved_root_name;
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if (!strncmp(root_device_name, "mtd", 3)) {
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mount_block_root(root_device_name, root_mountflags);
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goto out;
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}
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ROOT_DEV = name_to_dev_t(root_device_name);
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if (strncmp(root_device_name, "/dev/", 5) == 0)
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root_device_name += 5;
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}
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if (initrd_load())
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goto out;
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/* wait for any asynchronous scanning to complete */
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if ((ROOT_DEV == 0) && root_wait) {
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printk(KERN_INFO "Waiting for root device %s...\n",
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saved_root_name);
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while (driver_probe_done() != 0 ||
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(ROOT_DEV = name_to_dev_t(saved_root_name)) == 0)
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msleep(100);
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}
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is_floppy = MAJOR(ROOT_DEV) == FLOPPY_MAJOR;
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if (is_floppy && rd_doload && rd_load_disk(0))
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ROOT_DEV = Root_RAM0;
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mount_root();
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out:
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sys_mount(".", "/", NULL, MS_MOVE, NULL);
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sys_chroot(".");
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security_sb_post_mountroot();
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}
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