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紧急求救！！！对文件系统有研究的高手过来帮一下忙
Red Hat的源代码在util-linux包里，disk-utils的mkswap.c。
/*
* mkswap.c - set up a linux swap device
*
* (C) 1991 Linus Torvalds. This file may be redistributed as per
* the Linux copyright.
*/
/*
* 20.12.91 - time began. Got VM working yesterday by doing this by hand.
*
* Usage: mkswap [-c] [-vN] [-f] device [size-in-blocks]
*
* -c for readability checking. (Use it unless you are SURE!)
* -vN for swap areas version N. (Only N=0,1 known today.)
* -f for forcing swap creation even if it would smash partition table.
*
* The device may be a block device or an image of one, but this isn't
* enforced (but it's not much fun on a character device :-).
*
* Patches from jaggy@purplet.demon.co.uk (Mike Jagdis) to make the
* size-in-blocks parameter optional added Wed Feb 8 10:33:43 1995.
*
* Version 1 swap area code (for kernel 2.1.117), aeb, 981010.
*
* Sparc fixes, jj@ultra.linux.cz (Jakub Jelinek), 981201 - mangled by aeb.
* V1_MAX_PAGES fixes, jj, 990325.
* sparc64 fixes, jj, 000219.
*
* 1999-02-22 Arkadiusz Mi秌iewicz <misiek@pld.ORG.PL>;
* - added Native Language Support
*
*/
#include <stdio.h>;
#include <unistd.h>;
#include <string.h>;
#include <fcntl.h>;
#include <stdlib.h>;
#include <sys/ioctl.h>; /* for _IO */
#include <sys/utsname.h>;
#include <sys/stat.h>;
#include "nls.h"
/* Try to get PAGE_SIZE from libc or kernel includes */
#ifdef HAVE_sys_user_h
/* Note: <sys/user.h>; says: for gdb only */
#include <sys/user.h>; /* for PAGE_SIZE and PAGE_SHIFT */
#else
#ifdef HAVE_asm_page_h
#include <asm/page.h>; /* for PAGE_SIZE and PAGE_SHIFT */
/* we also get PAGE_SIZE via getpagesize() */
#endif
#endif
#ifndef _IO
/* pre-1.3.45 */
#define BLKGETSIZE 0x1260
#else
/* same on i386, m68k, arm; different on alpha, mips, sparc, ppc */
#define BLKGETSIZE _IO(0x12,96)
#endif
static char * program_name = "mkswap";
static char * device_name = NULL;
static int DEV = -1;
static long PAGES = 0;
static int check = 0;
static int badpages = 0;
static int version = -1;
#define MAKE_VERSION(p,q,r) (65536*(p) + 256*(q) + (r))
static int
linux_version_code(void) {
struct utsname my_utsname;
int p, q, r;
if (uname(&my_utsname) == 0) {
p = atoi(strtok(my_utsname.release, "."));
q = atoi(strtok(NULL, "."));
r = atoi(strtok(NULL, "."));
return MAKE_VERSION(p,q,r);
}
return 0;
}
#ifdef __sparc__
# ifdef __arch64__
# define is_sparc64() 1
# define is_be64() 1
# else /* sparc32 */
static int
is_sparc64(void) {
struct utsname un;
static int sparc64 = -1;
if (sparc64 != -1) return sparc64;
sparc64 = 0;
if (uname(&un) < 0) return 0;
if (! strcmp(un.machine, "sparc64")) {
sparc64 = 1;
return 1;
}
if (strcmp(un.machine, "sparc"))
return 0; /* Should not happen */
#ifdef HAVE_personality
{
extern int personality(unsigned long);
int oldpers;
#define PERS_LINUX 0x00000000
#define PERS_LINUX_32BIT 0x00800000
#define PERS_LINUX32 0x00000008
oldpers = personality(PERS_LINUX_32BIT);
if (oldpers != -1) {
if (personality(PERS_LINUX) != -1) {
uname(&un);
if (! strcmp(un.machine, "sparc64")) {
sparc64 = 1;
oldpers = PERS_LINUX32;
}
}
personality(oldpers);
}
}
#endif
return sparc64;
}
# define is_be64() is_sparc64()
# endif /* sparc32 */
#else /* !sparc */
# define is_be64() 0
#endif
/*
* The definition of the union swap_header uses the constant PAGE_SIZE.
* Unfortunately, on some architectures this depends on the hardware model,
* and can only be found at run time -- we use getpagesize(), so that
* we do not need separate binaries e.g. for sun4, sun4c/d/m and sun4u.
*
* Even more unfortunately, getpagesize() does not always return
* the right information. For example, libc4 and libc5 do not use
* the system call but invent a value themselves
* (EXEC_PAGESIZE or NBPG * CLSIZE or NBPC), and thus it may happen
* that e.g. on a sparc PAGE_SIZE=4096 and getpagesize() returns 8192.
* What to do? Let us allow the user to specify the pagesize explicitly.
*/
static int user_pagesize = 0;
static int kernel_pagesize; /* obtained via getpagesize(); */
static int defined_pagesize = 0; /* PAGE_SIZE, when that exists */
static int pagesize;
static long *signature_page;
struct swap_header_v1 {
char bootbits[1024]; /* Space for disklabel etc. */
unsigned int version;
unsigned int last_page;
unsigned int nr_badpages;
unsigned int padding[125];
unsigned int badpages[1];
} *p;
static void
init_signature_page(void) {
#ifdef PAGE_SIZE
defined_pagesize = PAGE_SIZE;
#endif
kernel_pagesize = getpagesize();
pagesize = kernel_pagesize;
if (user_pagesize) {
if ((user_pagesize & (user_pagesize-1)) ||
user_pagesize < 1024) {
fprintf(stderr, _("Bad user-specified page size %d\n"),
user_pagesize);
exit(1);
}
pagesize = user_pagesize;
}
if (user_pagesize && user_pagesize != kernel_pagesize &&
user_pagesize != defined_pagesize)
fprintf(stderr, _("Using user-specified page size %d, "
"instead of the system values %d/%d\n"),
pagesize, kernel_pagesize, defined_pagesize);
else if (defined_pagesize && pagesize != defined_pagesize)
fprintf(stderr, _("Assuming pages of size %d (not %d)\n"),
pagesize, defined_pagesize);
signature_page = (long *) malloc(pagesize);
memset(signature_page,0,pagesize);
p = (struct swap_header_v1 *) signature_page;
}
static void
write_signature(char *sig) {
char *sp = (char *) signature_page;
strncpy(sp+pagesize-10, sig, 10);
}
#define V0_MAX_PAGES (8 * (pagesize - 10))
/* Before 2.2.0pre9 */
#define V1_OLD_MAX_PAGES ((0x7fffffff / pagesize) - 1)
/* Since 2.2.0pre9:
error if nr of pages >;= SWP_OFFSET(SWP_ENTRY(0,~0UL))
with variations on
#define SWP_ENTRY(type,offset) (((type) << 1) | ((offset) << 8))
#define SWP_OFFSET(entry) ((entry) >;>; 8)
on the various architectures. Below the result - yuk.
Machine pagesize SWP_ENTRY SWP_OFFSET bound+1 oldbound+2
i386 2^12 o<<8 e>;>;8 1<<24 1<<19
mips 2^12 o<<15 e>;>;15 1<<17 1<<19
alpha 2^13 o<<40 e>;>;40 1<<24 1<<18
m68k 2^12 o<<12 e>;>;12 1<<20 1<<19
sparc 2^{12,13} (o&0x3ffff)<<9 (e>;>;9)&0x3ffff 1<<18 1<<{19,18}
sparc64 2^13 o<<13 e>;>;13 1<<51 1<<18
ppc 2^12 o<<8 e>;>;8 1<<24 1<<19
armo 2^{13,14,15} o<<8 e>;>;8 1<<24 1<<{18,17,16}
armv 2^12 o<<9 e>;>;9 1<<23 1<<19
assuming that longs have 64 bits on alpha and sparc64 and 32 bits elsewhere.
The bad part is that we need to know this since the kernel will
refuse a swap space if it is too large.
*/
/* patch from jj - why does this differ from the above? */
/* 32bit kernels have a second limitation of 2GB, sparc64 is limited by
the size of virtual address space allocation for vmalloc */
#if defined(__alpha__)
#define V1_MAX_PAGES ((1 << 24) - 1)
#elif defined(__mips__)
#define V1_MAX_PAGES ((1 << 17) - 1)
#elif defined(__sparc__)
#define V1_MAX_PAGES (is_sparc64() ? ((3 << 29) - 1) : ((1 << 18) - 1))
#elif defined(__ia64__)
/*
* The actual size will depend on the amount of virtual address space
* available to vmalloc the swap map.
*/
#define V1_MAX_PAGES ((1UL << 54) - 1)
#else
#define V1_MAX_PAGES V1_OLD_MAX_PAGES
#endif
/* man page now says:
The maximum useful size of a swap area now depends on the architecture.
It is roughly 2GB on i386, PPC, m68k, ARM, 1GB on sparc, 512MB on mips,
128GB on alpha and 3TB on sparc64.
*/
#define MAX_BADPAGES ((pagesize-1024-128*sizeof(int)-10)/sizeof(int))
/*
* One more point of lossage - Linux swapspace really is a mess.
* The definition of the bitmap used is architecture dependent,
* and requires one to know whether the machine is bigendian,
* and if so, whether it will use 32-bit or 64-bit units in
* test_bit().
* davem writes: "... is based upon an unsigned long type of
* the cpu and the native endianness".
* So, it seems we can write `unsigned long' below.
* However, sparc64 uses 64-bit units in the kernel, while
* mkswap may have been translated with 32-bit longs. Thus,
* we need an explicit test for version 0 swap on sparc64.
*/
static void
bit_set (unsigned long *addr, unsigned int nr) {
unsigned int r, m;
if(is_be64()) {
unsigned long long *bitmap = (unsigned long long *) addr;
unsigned long long bitnum = (unsigned long long) nr;
unsigned long long rl, ml;
bitmap += bitnum / (8 * sizeof(long long));
rl = *bitmap;
ml = 1ULL << (bitnum &
(8ULL * (unsigned long long)sizeof(long long) - 1ULL));
*bitmap = rl | ml;
return;
}
addr += nr / (8 * sizeof(unsigned long));
r = *addr;
m = 1 << (nr & (8 * sizeof(unsigned long) - 1));
*addr = r | m;
}
static int
bit_test_and_clear (unsigned long *addr, unsigned int nr) {
unsigned int r, m;
if(is_be64()) {
unsigned long long *bitmap = (unsigned long long *) addr;
unsigned long long bitnum = (unsigned long long) nr;
unsigned long long rl, ml;
bitmap += bitnum / (8 * sizeof(long long));
rl = *bitmap;
ml = 1ULL << (bitnum &
(8ULL * (unsigned long long)sizeof(long long) - 1ULL));
*bitmap = rl & ~ml;
return ((rl & ml) != 0ULL);
}
addr += nr / (8 * sizeof(unsigned long));
r = *addr;
m = 1 << (nr & (8 * sizeof(unsigned long) - 1));
*addr = r & ~m;
return (r & m) != 0;
}
static void
usage(void) {
fprintf(stderr,
_("Usage: %s [-c] [-v0|-v1] [-pPAGESZ] /dev/name [blocks]\n"),
program_name);
exit(1);
}
static void
die(const char *str) {
fprintf(stderr, "%s: %s\n", program_name, str);
exit(1);
}
static void
page_ok(int page) {
if (version==0)
bit_set(signature_page, page);
}
static void
page_bad(int page) {
if (version == 0)
bit_test_and_clear(signature_page, page);
else {
if (badpages == MAX_BADPAGES)
die(_("too many bad pages"));
p->;badpages[badpages] = page;
}
badpages++;
}
static void
check_blocks(void) {
unsigned int current_page;
int do_seek = 1;
char *buffer;
buffer = malloc(pagesize);
if (!buffer)
die(_("Out of memory"));
current_page = 0;
while (current_page < PAGES) {
if (!check) {
page_ok(current_page++);
continue;
}
if (do_seek && lseek(DEV,current_page*pagesize,SEEK_SET) !=
current_page*pagesize)
die(_("seek failed in check_blocks"));
if ((do_seek = (pagesize != read(DEV, buffer, pagesize)))) {
page_bad(current_page++);
continue;
}
page_ok(current_page++);
}
if (badpages == 1)
printf(_("one bad page\n"));
else if (badpages >; 1)
printf(_("%d bad pages\n"), badpages);
}
static long
valid_offset (int fd, off_t offset) {
char ch;
if (lseek (fd, offset, 0) < 0)
return 0;
if (read (fd, &ch, 1) < 1)
return 0;
return 1;
}
static off_t
find_size (int fd) {
off_t high, low;
low = 0;
for (high = 1; high >; 0 && valid_offset (fd, high); high *= 2)
low = high;
while (low < high - 1) {
const off_t mid = (low + high) / 2;
if (valid_offset (fd, mid))
low = mid;
else
high = mid;
}
return (low + 1);
}
/* return size in pages, to avoid integer overflow */
static long
get_size(const char *file) {
int fd;
long size;
fd = open(file, O_RDONLY);
if (fd < 0) {
perror(file);
exit(1);
}
if (ioctl(fd, BLKGETSIZE, &size) >;= 0) {
int sectors_per_page = pagesize/512;
size /= sectors_per_page;
} else {
size = find_size(fd) / pagesize;
}
close(fd);
return size;
}
static int
isnzdigit(char c) {
return (c >;= '1' && c <= '9');
}
int
main(int argc, char ** argv) {
struct stat statbuf;
int i, sz;
long maxpages;
long goodpages;
off_t offset;
int force = 0;
char *block_count = 0;
char *pp;
program_name = (argc && *argv) ? argv[0] : "fsck.minix";
if ((pp = strrchr(program_name, '/')) != NULL)
program_name = pp+1;
setlocale(LC_ALL, "");
bindtextdomain(PACKAGE, LOCALEDIR);
textdomain(PACKAGE);
if (argc == 2 &&
(!strcmp(argv[1], "-V") || !strcmp(argv[1], "--version"))) {
printf(_("%s from %s\n"), program_name, util_linux_version);
exit(0);
}
for (i=1; i<argc; i++) {
if (argv[i][0] == '-') {
switch (argv[i][1]) {
case 'c':
check=1;
break;
case 'f':
force=1;
break;
case 'p':
pp = argv[i]+2;
if (!*pp && i+1 < argc)
pp = argv[++i];
if (isnzdigit(*pp))
user_pagesize=atoi(pp);
else
usage();
break;
case 'v':
version = atoi(argv[i]+2);
break;
default:
usage();
}
} else if (!device_name) {
device_name = argv[i];
} else if (!block_count) {
block_count = argv[i];
} else
usage();
}
init_signature_page(); /* get pagesize */
if (!device_name) {
fprintf(stderr,
_("%s: error: Nowhere to set up swap on?\n"),
program_name);
usage();
}
if (block_count) {
/* this silly user specified the number of blocks
explicitly */
char *tmp;
int blocks_per_page = pagesize/1024;
PAGES = strtol(block_count,&tmp,0)/blocks_per_page;
if (*tmp)
usage();
}
sz = get_size(device_name);
if (!PAGES) {
PAGES = sz;
} else if (PAGES >; sz && !force) {
fprintf(stderr,
_("%s: error: "
"size %ld is larger than device size %d\n"),
program_name,
PAGES*(pagesize/1024), sz*(pagesize/1024));
exit(1);
}
if (version == -1) {
/* use version 1 as default, if possible */
if (PAGES <= V0_MAX_PAGES && PAGES >; V1_MAX_PAGES)
version = 0;
else if (linux_version_code() < MAKE_VERSION(2,1,117))
version = 0;
else if (pagesize < 2048)
version = 0;
else
version = 1;
}
if (version != 0 && version != 1) {
fprintf(stderr, _("%s: error: unknown version %d\n"),
program_name, version);
usage();
}
if (PAGES < 10) {
fprintf(stderr,
_("%s: error: swap area needs to be at least %ldkB\n"),
program_name, (long)(10 * pagesize / 1024));
usage();
}
#if 0
maxpages = ((version == 0) ? V0_MAX_PAGES : V1_MAX_PAGES);
#else
if (!version)
maxpages = V0_MAX_PAGES;
else if (linux_version_code() >;= MAKE_VERSION(2,2,1))
maxpages = V1_MAX_PAGES;
else {
maxpages = V1_OLD_MAX_PAGES;
if (maxpages >; V1_MAX_PAGES)
maxpages = V1_MAX_PAGES;
}
#endif
if (PAGES >; maxpages) {
PAGES = maxpages;
fprintf(stderr, _("%s: warning: truncating swap area to %ldkB\n"),
program_name, PAGES * pagesize / 1024);
}
DEV = open(device_name,O_RDWR);
if (DEV < 0 || fstat(DEV, &statbuf) < 0) {
perror(device_name);
exit(1);
}
if (!S_ISBLK(statbuf.st_mode))
check=0;
else if (statbuf.st_rdev == 0x0300 || statbuf.st_rdev == 0x0340)
die(_("Will not try to make swapdevice on '%s'"));
#ifdef __sparc__
if (!force && version == 0) {
/* Don't overwrite partition table unless forced */
unsigned char *buffer = (unsigned char *)signature_page;
unsigned short *q, sum;
if (read(DEV, buffer, 512) != 512)
die(_("fatal: first page unreadable"));
if (buffer[508] == 0xDA && buffer[509] == 0xBE) {
q = (unsigned short *)(buffer + 510);
for (sum = 0; q >;= (unsigned short *) buffer;)
sum ^= *q--;
if (!sum) {
fprintf(stderr, _("\
%s: Device '%s' contains a valid Sun disklabel.\n\
This probably means creating v0 swap would destroy your partition table\n\
No swap created. If you really want to create swap v0 on that device, use\n\
the -f option to force it.\n"),
program_name, device_name);
exit(1);
}
}
}
#endif
if (version == 0 || check)
check_blocks();
if (version == 0 && !bit_test_and_clear(signature_page,0))
die(_("fatal: first page unreadable"));
if (version == 1) {
p->;version = version;
p->;last_page = PAGES-1;
p->;nr_badpages = badpages;
}
goodpages = PAGES - badpages - 1;
if (goodpages <= 0)
die(_("Unable to set up swap-space: unreadable"));
printf(_("Setting up swapspace version %d, size = %lu KiB\n"),
version, (unsigned long)goodpages * pagesize / 1024);
write_signature((version == 0) ? "SWAP-SPACE" : "SWAPSPACE2");
offset = ((version == 0) ? 0 : 1024);
if (lseek(DEV, offset, SEEK_SET) != offset)
die(_("unable to rewind swap-device"));
if (write(DEV,(char*)signature_page+offset, pagesize-offset)
!= pagesize-offset)
die(_("unable to write signature page"));
/*
* A subsequent swapon() will fail if the signature
* is not actually on disk. (This is a kernel bug.)
*/
#ifdef HAVE_fsync
if (fsync(DEV))
die(_("fsync failed"));
#endif
return 0;
} |
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发表于 2004-12-14 11:25
