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/*
* Helper functions for multiple mount protection (MMP).
*
* Copyright (C) 2011 Whamcloud, Inc.
*
* %Begin-Header%
* This file may be redistributed under the terms of the GNU Library
* General Public License, version 2.
* %End-Header%
*/
#ifndef _GNU_SOURCE
#define _GNU_SOURCE
#endif
#ifndef _DEFAULT_SOURCE
#define _DEFAULT_SOURCE /* since glibc 2.20 _SVID_SOURCE is deprecated */
#endif
#include "config.h"
#if HAVE_UNISTD_H
#include <unistd.h>
#endif
#include <sys/time.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include "ext2fs/ext2_fs.h"
#include "ext2fs/ext2fs.h"
#ifndef O_DIRECT
#define O_DIRECT 0
#endif
#if __GNUC_PREREQ (4, 6)
#pragma GCC diagnostic push
#ifndef CONFIG_MMP
#pragma GCC diagnostic ignored "-Wunused-parameter"
#endif
#endif
errcode_t ext2fs_mmp_read(ext2_filsys fs, blk64_t mmp_blk, void *buf)
{
#ifdef CONFIG_MMP
struct mmp_struct *mmp_cmp;
errcode_t retval = 0;
if ((mmp_blk <= fs->super->s_first_data_block) ||
(mmp_blk >= ext2fs_blocks_count(fs->super)))
return EXT2_ET_MMP_BAD_BLOCK;
/* ext2fs_open() reserves fd0,1,2 to avoid stdio collision, so checking
* mmp_fd <= 0 is OK to validate that the fd is valid. This opens its
* own fd to read the MMP block to ensure that it is using O_DIRECT,
* regardless of how the io_manager is doing reads, to avoid caching of
* the MMP block by the io_manager or the VM. It needs to be fresh. */
if (fs->mmp_fd <= 0) {
struct stat st;
int flags = O_RDONLY | O_DIRECT;
/*
* There is no reason for using O_DIRECT if we're working with
* regular file. Disabling it also avoids problems with
* alignment when the device of the host file system has sector
* size larger than blocksize of the fs we're working with.
*/
if (stat(fs->device_name, &st) == 0 &&
S_ISREG(st.st_mode))
flags &= ~O_DIRECT;
fs->mmp_fd = open(fs->device_name, flags);
if (fs->mmp_fd < 0) {
retval = EXT2_ET_MMP_OPEN_DIRECT;
goto out;
}
}
if (fs->mmp_cmp == NULL) {
int align = ext2fs_get_dio_alignment(fs->mmp_fd);
retval = ext2fs_get_memalign(fs->blocksize, align,
&fs->mmp_cmp);
if (retval)
return retval;
}
if ((blk64_t) ext2fs_llseek(fs->mmp_fd, mmp_blk * fs->blocksize,
SEEK_SET) !=
mmp_blk * fs->blocksize) {
retval = EXT2_ET_LLSEEK_FAILED;
goto out;
}
if (read(fs->mmp_fd, fs->mmp_cmp, fs->blocksize) != fs->blocksize) {
retval = EXT2_ET_SHORT_READ;
goto out;
}
mmp_cmp = fs->mmp_cmp;
if (!(fs->flags & EXT2_FLAG_IGNORE_CSUM_ERRORS) &&
!ext2fs_mmp_csum_verify(fs, mmp_cmp))
retval = EXT2_ET_MMP_CSUM_INVALID;
#ifdef WORDS_BIGENDIAN
ext2fs_swap_mmp(mmp_cmp);
#endif
if (buf != NULL && buf != fs->mmp_cmp)
memcpy(buf, fs->mmp_cmp, fs->blocksize);
if (mmp_cmp->mmp_magic != EXT4_MMP_MAGIC) {
retval = EXT2_ET_MMP_MAGIC_INVALID;
goto out;
}
out:
return retval;
#else
return EXT2_ET_OP_NOT_SUPPORTED;
#endif
}
errcode_t ext2fs_mmp_write(ext2_filsys fs, blk64_t mmp_blk, void *buf)
{
#ifdef CONFIG_MMP
struct mmp_struct *mmp_s = buf;
struct timeval tv;
errcode_t retval = 0;
gettimeofday(&tv, 0);
mmp_s->mmp_time = tv.tv_sec;
fs->mmp_last_written = tv.tv_sec;
if (fs->super->s_mmp_block < fs->super->s_first_data_block ||
fs->super->s_mmp_block > ext2fs_blocks_count(fs->super))
return EXT2_ET_MMP_BAD_BLOCK;
#ifdef WORDS_BIGENDIAN
ext2fs_swap_mmp(mmp_s);
#endif
retval = ext2fs_mmp_csum_set(fs, mmp_s);
if (retval)
return retval;
/* I was tempted to make this use O_DIRECT and the mmp_fd, but
* this caused no end of grief, while leaving it as-is works. */
retval = io_channel_write_blk64(fs->io, mmp_blk, -(int)sizeof(struct mmp_struct), buf);
#ifdef WORDS_BIGENDIAN
ext2fs_swap_mmp(mmp_s);
#endif
/* Make sure the block gets to disk quickly */
io_channel_flush(fs->io);
return retval;
#else
return EXT2_ET_OP_NOT_SUPPORTED;
#endif
}
#ifdef HAVE_SRANDOM
#define srand(x) srandom(x)
#define rand() random()
#endif
unsigned ext2fs_mmp_new_seq(void)
{
#ifdef CONFIG_MMP
unsigned new_seq;
struct timeval tv;
unsigned long pid = getpid();
gettimeofday(&tv, 0);
pid = (pid >> 16) | ((pid & 0xFFFF) << 16);
srand(pid ^ getuid() ^ tv.tv_sec ^ tv.tv_usec);
gettimeofday(&tv, 0);
/* Crank the random number generator a few times */
for (new_seq = (tv.tv_sec ^ tv.tv_usec) & 0x1F; new_seq > 0; new_seq--)
rand();
do {
new_seq = rand();
} while (new_seq > EXT4_MMP_SEQ_MAX);
return new_seq;
#else
return EXT2_ET_OP_NOT_SUPPORTED;
#endif
}
#ifdef CONFIG_MMP
static errcode_t ext2fs_mmp_reset(ext2_filsys fs)
{
struct mmp_struct *mmp_s = NULL;
errcode_t retval = 0;
if (fs->mmp_buf == NULL) {
retval = ext2fs_get_mem(fs->blocksize, &fs->mmp_buf);
if (retval)
goto out;
}
memset(fs->mmp_buf, 0, fs->blocksize);
mmp_s = fs->mmp_buf;
mmp_s->mmp_magic = EXT4_MMP_MAGIC;
mmp_s->mmp_seq = EXT4_MMP_SEQ_CLEAN;
mmp_s->mmp_time = 0;
#ifdef HAVE_GETHOSTNAME
gethostname((char *) mmp_s->mmp_nodename, sizeof(mmp_s->mmp_nodename));
#else
mmp_s->mmp_nodename[0] = '\0';
#endif
strncpy((char *) mmp_s->mmp_bdevname, fs->device_name,
sizeof(mmp_s->mmp_bdevname));
mmp_s->mmp_check_interval = fs->super->s_mmp_update_interval;
if (mmp_s->mmp_check_interval < EXT4_MMP_MIN_CHECK_INTERVAL)
mmp_s->mmp_check_interval = EXT4_MMP_MIN_CHECK_INTERVAL;
retval = ext2fs_mmp_write(fs, fs->super->s_mmp_block, fs->mmp_buf);
out:
return retval;
}
#endif
errcode_t ext2fs_mmp_update(ext2_filsys fs)
{
return ext2fs_mmp_update2(fs, 0);
}
errcode_t ext2fs_mmp_clear(ext2_filsys fs)
{
#ifdef CONFIG_MMP
errcode_t retval = 0;
if (!(fs->flags & EXT2_FLAG_RW))
return EXT2_ET_RO_FILSYS;
retval = ext2fs_mmp_reset(fs);
return retval;
#else
return EXT2_ET_OP_NOT_SUPPORTED;
#endif
}
errcode_t ext2fs_mmp_init(ext2_filsys fs)
{
#ifdef CONFIG_MMP
struct ext2_super_block *sb = fs->super;
blk64_t mmp_block;
errcode_t retval;
if (sb->s_mmp_update_interval == 0)
sb->s_mmp_update_interval = EXT4_MMP_UPDATE_INTERVAL;
/* This is probably excessively large, but who knows? */
else if (sb->s_mmp_update_interval > EXT4_MMP_MAX_UPDATE_INTERVAL)
return EXT2_ET_INVALID_ARGUMENT;
if (fs->mmp_buf == NULL) {
retval = ext2fs_get_mem(fs->blocksize, &fs->mmp_buf);
if (retval)
goto out;
}
retval = ext2fs_alloc_block2(fs, 0, fs->mmp_buf, &mmp_block);
if (retval)
goto out;
sb->s_mmp_block = mmp_block;
retval = ext2fs_mmp_reset(fs);
if (retval)
goto out;
out:
return retval;
#else
return EXT2_ET_OP_NOT_SUPPORTED;
#endif
}
#ifndef min
#define min(x, y) ((x) < (y) ? (x) : (y))
#endif
/*
* Make sure that the fs is not mounted or being fsck'ed while opening the fs.
*/
errcode_t ext2fs_mmp_start(ext2_filsys fs)
{
#ifdef CONFIG_MMP
struct mmp_struct *mmp_s;
unsigned seq;
unsigned int mmp_check_interval;
errcode_t retval = 0;
if (fs->mmp_buf == NULL) {
retval = ext2fs_get_mem(fs->blocksize, &fs->mmp_buf);
if (retval)
goto mmp_error;
}
retval = ext2fs_mmp_read(fs, fs->super->s_mmp_block, fs->mmp_buf);
if (retval)
goto mmp_error;
mmp_s = fs->mmp_buf;
mmp_check_interval = fs->super->s_mmp_update_interval;
if (mmp_check_interval < EXT4_MMP_MIN_CHECK_INTERVAL)
mmp_check_interval = EXT4_MMP_MIN_CHECK_INTERVAL;
seq = mmp_s->mmp_seq;
if (seq == EXT4_MMP_SEQ_CLEAN)
goto clean_seq;
if (seq == EXT4_MMP_SEQ_FSCK) {
retval = EXT2_ET_MMP_FSCK_ON;
goto mmp_error;
}
if (seq > EXT4_MMP_SEQ_FSCK) {
retval = EXT2_ET_MMP_UNKNOWN_SEQ;
goto mmp_error;
}
/*
* If check_interval in MMP block is larger, use that instead of
* check_interval from the superblock.
*/
if (mmp_s->mmp_check_interval > mmp_check_interval)
mmp_check_interval = mmp_s->mmp_check_interval;
sleep(min(mmp_check_interval * 2 + 1, mmp_check_interval + 60));
retval = ext2fs_mmp_read(fs, fs->super->s_mmp_block, fs->mmp_buf);
if (retval)
goto mmp_error;
if (seq != mmp_s->mmp_seq) {
retval = EXT2_ET_MMP_FAILED;
goto mmp_error;
}
clean_seq:
if (!(fs->flags & EXT2_FLAG_RW))
goto mmp_error;
mmp_s->mmp_seq = seq = ext2fs_mmp_new_seq();
#ifdef HAVE_GETHOSTNAME
gethostname((char *) mmp_s->mmp_nodename, sizeof(mmp_s->mmp_nodename));
#else
strcpy((char *) mmp_s->mmp_nodename, "unknown host");
#endif
strncpy((char *) mmp_s->mmp_bdevname, fs->device_name,
sizeof(mmp_s->mmp_bdevname));
retval = ext2fs_mmp_write(fs, fs->super->s_mmp_block, fs->mmp_buf);
if (retval)
goto mmp_error;
sleep(min(2 * mmp_check_interval + 1, mmp_check_interval + 60));
retval = ext2fs_mmp_read(fs, fs->super->s_mmp_block, fs->mmp_buf);
if (retval)
goto mmp_error;
if (seq != mmp_s->mmp_seq) {
retval = EXT2_ET_MMP_FAILED;
goto mmp_error;
}
mmp_s->mmp_seq = EXT4_MMP_SEQ_FSCK;
retval = ext2fs_mmp_write(fs, fs->super->s_mmp_block, fs->mmp_buf);
if (retval)
goto mmp_error;
return 0;
mmp_error:
return retval;
#else
return EXT2_ET_OP_NOT_SUPPORTED;
#endif
}
/*
* Clear the MMP usage in the filesystem. If this function returns an
* error EXT2_ET_MMP_CHANGE_ABORT it means the filesystem was modified
* by some other process while in use, and changes should be dropped, or
* risk filesystem corruption.
*/
errcode_t ext2fs_mmp_stop(ext2_filsys fs)
{
#ifdef CONFIG_MMP
struct mmp_struct *mmp, *mmp_cmp;
errcode_t retval = 0;
if (!ext2fs_has_feature_mmp(fs->super) ||
!(fs->flags & EXT2_FLAG_RW) || (fs->flags & EXT2_FLAG_SKIP_MMP) ||
(fs->mmp_buf == NULL) || (fs->mmp_cmp == NULL))
goto mmp_error;
retval = ext2fs_mmp_read(fs, fs->super->s_mmp_block, NULL);
if (retval)
goto mmp_error;
/* Check if the MMP block is not changed. */
mmp = fs->mmp_buf;
mmp_cmp = fs->mmp_cmp;
if (memcmp(mmp, mmp_cmp, sizeof(*mmp_cmp))) {
retval = EXT2_ET_MMP_CHANGE_ABORT;
goto mmp_error;
}
mmp_cmp->mmp_seq = EXT4_MMP_SEQ_CLEAN;
retval = ext2fs_mmp_write(fs, fs->super->s_mmp_block, fs->mmp_cmp);
mmp_error:
if (fs->mmp_fd > 0) {
close(fs->mmp_fd);
fs->mmp_fd = -1;
}
return retval;
#else
if (!ext2fs_has_feature_mmp(fs->super) ||
!(fs->flags & EXT2_FLAG_RW) || (fs->flags & EXT2_FLAG_SKIP_MMP))
return 0;
return EXT2_ET_OP_NOT_SUPPORTED;
#endif
}
#define EXT2_MIN_MMP_UPDATE_INTERVAL 60
/*
* Update the on-disk mmp buffer, after checking that it hasn't been changed.
*/
errcode_t ext2fs_mmp_update2(ext2_filsys fs, int immediately)
{
#ifdef CONFIG_MMP
struct mmp_struct *mmp, *mmp_cmp;
struct timeval tv;
errcode_t retval = 0;
if (!ext2fs_has_feature_mmp(fs->super) ||
!(fs->flags & EXT2_FLAG_RW) || (fs->flags & EXT2_FLAG_SKIP_MMP))
return 0;
gettimeofday(&tv, 0);
if (!immediately &&
tv.tv_sec - fs->mmp_last_written < EXT2_MIN_MMP_UPDATE_INTERVAL)
return 0;
retval = ext2fs_mmp_read(fs, fs->super->s_mmp_block, NULL);
if (retval)
goto mmp_error;
mmp = fs->mmp_buf;
mmp_cmp = fs->mmp_cmp;
if (memcmp(mmp, mmp_cmp, sizeof(*mmp_cmp)))
return EXT2_ET_MMP_CHANGE_ABORT;
mmp->mmp_time = tv.tv_sec;
mmp->mmp_seq = EXT4_MMP_SEQ_FSCK;
retval = ext2fs_mmp_write(fs, fs->super->s_mmp_block, fs->mmp_buf);
mmp_error:
return retval;
#else
if (!ext2fs_has_feature_mmp(fs->super) ||
!(fs->flags & EXT2_FLAG_RW) || (fs->flags & EXT2_FLAG_SKIP_MMP))
return 0;
return EXT2_ET_OP_NOT_SUPPORTED;
#endif
}
#if __GNUC_PREREQ (4, 6)
#pragma GCC diagnostic pop
#endif
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