2011-09-24 21:48:55 +04:00
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/*
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* Helper functions for multiple mount protection (MMP).
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*
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* Copyright (C) 2011 Whamcloud, Inc.
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*
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* %Begin-Header%
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2012-11-23 02:29:15 +04:00
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* This file may be redistributed under the terms of the GNU Library
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* General Public License, version 2.
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2011-09-24 21:48:55 +04:00
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* %End-Header%
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*/
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#ifndef _GNU_SOURCE
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#define _GNU_SOURCE
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#endif
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2012-02-27 10:12:53 +04:00
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#include "config.h"
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2011-09-24 21:48:55 +04:00
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#if HAVE_UNISTD_H
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#include <unistd.h>
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#endif
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#include <sys/time.h>
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <fcntl.h>
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#include "ext2fs/ext2_fs.h"
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#include "ext2fs/ext2fs.h"
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#ifndef O_DIRECT
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#define O_DIRECT 0
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#endif
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errcode_t ext2fs_mmp_read(ext2_filsys fs, blk64_t mmp_blk, void *buf)
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{
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struct mmp_struct *mmp_cmp;
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errcode_t retval = 0;
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if ((mmp_blk <= fs->super->s_first_data_block) ||
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(mmp_blk >= fs->super->s_blocks_count))
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return EXT2_ET_MMP_BAD_BLOCK;
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/* ext2fs_open() reserves fd0,1,2 to avoid stdio collision, so checking
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* mmp_fd <= 0 is OK to validate that the fd is valid. This opens its
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* own fd to read the MMP block to ensure that it is using O_DIRECT,
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* regardless of how the io_manager is doing reads, to avoid caching of
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* the MMP block by the io_manager or the VM. It needs to be fresh. */
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if (fs->mmp_fd <= 0) {
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fs->mmp_fd = open(fs->device_name, O_RDWR | O_DIRECT);
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if (fs->mmp_fd < 0) {
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retval = EXT2_ET_MMP_OPEN_DIRECT;
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goto out;
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}
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}
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2012-05-07 21:25:44 +04:00
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if (fs->mmp_cmp == NULL) {
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int align = ext2fs_get_dio_alignment(fs->mmp_fd);
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retval = ext2fs_get_memalign(fs->blocksize, align,
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&fs->mmp_cmp);
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if (retval)
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return retval;
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}
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2011-09-24 21:48:55 +04:00
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if (ext2fs_llseek(fs->mmp_fd, mmp_blk * fs->blocksize, SEEK_SET) !=
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mmp_blk * fs->blocksize) {
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retval = EXT2_ET_LLSEEK_FAILED;
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goto out;
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}
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if (read(fs->mmp_fd, fs->mmp_cmp, fs->blocksize) != fs->blocksize) {
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retval = EXT2_ET_SHORT_READ;
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goto out;
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}
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mmp_cmp = fs->mmp_cmp;
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2011-09-30 23:41:26 +04:00
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#ifdef WORDS_BIGENDIAN
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ext2fs_swap_mmp(mmp_cmp);
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2011-09-24 21:48:55 +04:00
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#endif
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if (buf != NULL && buf != fs->mmp_cmp)
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memcpy(buf, fs->mmp_cmp, fs->blocksize);
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if (mmp_cmp->mmp_magic != EXT4_MMP_MAGIC) {
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retval = EXT2_ET_MMP_MAGIC_INVALID;
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goto out;
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}
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out:
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return retval;
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}
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errcode_t ext2fs_mmp_write(ext2_filsys fs, blk64_t mmp_blk, void *buf)
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{
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struct mmp_struct *mmp_s = buf;
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struct timeval tv;
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errcode_t retval = 0;
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gettimeofday(&tv, 0);
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mmp_s->mmp_time = tv.tv_sec;
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fs->mmp_last_written = tv.tv_sec;
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if (fs->super->s_mmp_block < fs->super->s_first_data_block ||
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fs->super->s_mmp_block > ext2fs_blocks_count(fs->super))
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return EXT2_ET_MMP_BAD_BLOCK;
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2011-09-30 23:41:26 +04:00
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#ifdef WORDS_BIGENDIAN
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ext2fs_swap_mmp(mmp_s);
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2011-09-24 21:48:55 +04:00
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#endif
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/* I was tempted to make this use O_DIRECT and the mmp_fd, but
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* this caused no end of grief, while leaving it as-is works. */
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2011-11-12 06:06:04 +04:00
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retval = io_channel_write_blk64(fs->io, mmp_blk, -(int)sizeof(struct mmp_struct), buf);
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2011-09-24 21:48:55 +04:00
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2011-09-30 23:41:26 +04:00
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#ifdef WORDS_BIGENDIAN
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ext2fs_swap_mmp(mmp_s);
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2011-09-24 21:48:55 +04:00
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#endif
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/* Make sure the block gets to disk quickly */
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io_channel_flush(fs->io);
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return retval;
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}
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#ifdef HAVE_SRANDOM
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#define srand(x) srandom(x)
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#define rand() random()
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#endif
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unsigned ext2fs_mmp_new_seq()
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{
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unsigned new_seq;
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struct timeval tv;
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gettimeofday(&tv, 0);
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srand((getpid() << 16) ^ getuid() ^ tv.tv_sec ^ tv.tv_usec);
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gettimeofday(&tv, 0);
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/* Crank the random number generator a few times */
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for (new_seq = (tv.tv_sec ^ tv.tv_usec) & 0x1F; new_seq > 0; new_seq--)
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rand();
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do {
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new_seq = rand();
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} while (new_seq > EXT4_MMP_SEQ_MAX);
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return new_seq;
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}
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static errcode_t ext2fs_mmp_reset(ext2_filsys fs)
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{
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struct mmp_struct *mmp_s = NULL;
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errcode_t retval = 0;
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if (fs->mmp_buf == NULL) {
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retval = ext2fs_get_mem(fs->blocksize, &fs->mmp_buf);
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if (retval)
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goto out;
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}
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memset(fs->mmp_buf, 0, fs->blocksize);
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mmp_s = fs->mmp_buf;
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mmp_s->mmp_magic = EXT4_MMP_MAGIC;
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mmp_s->mmp_seq = EXT4_MMP_SEQ_CLEAN;
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mmp_s->mmp_time = 0;
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#if _BSD_SOURCE || _XOPEN_SOURCE >= 500
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gethostname(mmp_s->mmp_nodename, sizeof(mmp_s->mmp_nodename));
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#else
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mmp_s->mmp_nodename[0] = '\0';
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#endif
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strncpy(mmp_s->mmp_bdevname, fs->device_name,
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sizeof(mmp_s->mmp_bdevname));
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mmp_s->mmp_check_interval = fs->super->s_mmp_update_interval;
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if (mmp_s->mmp_check_interval < EXT4_MMP_MIN_CHECK_INTERVAL)
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mmp_s->mmp_check_interval = EXT4_MMP_MIN_CHECK_INTERVAL;
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retval = ext2fs_mmp_write(fs, fs->super->s_mmp_block, fs->mmp_buf);
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out:
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return retval;
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}
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errcode_t ext2fs_mmp_clear(ext2_filsys fs)
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{
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errcode_t retval = 0;
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if (!(fs->flags & EXT2_FLAG_RW))
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return EXT2_ET_RO_FILSYS;
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retval = ext2fs_mmp_reset(fs);
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return retval;
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}
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errcode_t ext2fs_mmp_init(ext2_filsys fs)
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{
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struct ext2_super_block *sb = fs->super;
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blk64_t mmp_block;
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errcode_t retval;
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if (sb->s_mmp_update_interval == 0)
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sb->s_mmp_update_interval = EXT4_MMP_UPDATE_INTERVAL;
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/* This is probably excessively large, but who knows? */
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else if (sb->s_mmp_update_interval > EXT4_MMP_MAX_UPDATE_INTERVAL)
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return EXT2_ET_INVALID_ARGUMENT;
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if (fs->mmp_buf == NULL) {
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retval = ext2fs_get_mem(fs->blocksize, &fs->mmp_buf);
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if (retval)
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goto out;
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}
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retval = ext2fs_alloc_block2(fs, 0, fs->mmp_buf, &mmp_block);
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if (retval)
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goto out;
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sb->s_mmp_block = mmp_block;
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retval = ext2fs_mmp_reset(fs);
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if (retval)
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goto out;
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out:
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return retval;
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}
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/*
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* Make sure that the fs is not mounted or being fsck'ed while opening the fs.
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*/
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errcode_t ext2fs_mmp_start(ext2_filsys fs)
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{
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struct mmp_struct *mmp_s;
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unsigned seq;
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unsigned int mmp_check_interval;
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errcode_t retval = 0;
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if (fs->mmp_buf == NULL) {
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retval = ext2fs_get_mem(fs->blocksize, &fs->mmp_buf);
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if (retval)
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goto mmp_error;
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}
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retval = ext2fs_mmp_read(fs, fs->super->s_mmp_block, fs->mmp_buf);
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if (retval)
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goto mmp_error;
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mmp_s = fs->mmp_buf;
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mmp_check_interval = fs->super->s_mmp_update_interval;
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if (mmp_check_interval < EXT4_MMP_MIN_CHECK_INTERVAL)
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mmp_check_interval = EXT4_MMP_MIN_CHECK_INTERVAL;
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seq = mmp_s->mmp_seq;
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if (seq == EXT4_MMP_SEQ_CLEAN)
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goto clean_seq;
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if (seq == EXT4_MMP_SEQ_FSCK) {
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retval = EXT2_ET_MMP_FSCK_ON;
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goto mmp_error;
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}
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if (seq > EXT4_MMP_SEQ_FSCK) {
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retval = EXT2_ET_MMP_UNKNOWN_SEQ;
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goto mmp_error;
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}
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/*
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* If check_interval in MMP block is larger, use that instead of
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* check_interval from the superblock.
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*/
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if (mmp_s->mmp_check_interval > mmp_check_interval)
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mmp_check_interval = mmp_s->mmp_check_interval;
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sleep(2 * mmp_check_interval + 1);
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retval = ext2fs_mmp_read(fs, fs->super->s_mmp_block, fs->mmp_buf);
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if (retval)
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goto mmp_error;
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if (seq != mmp_s->mmp_seq) {
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retval = EXT2_ET_MMP_FAILED;
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goto mmp_error;
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}
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clean_seq:
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if (!(fs->flags & EXT2_FLAG_RW))
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goto mmp_error;
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mmp_s->mmp_seq = seq = ext2fs_mmp_new_seq();
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#if _BSD_SOURCE || _XOPEN_SOURCE >= 500
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gethostname(mmp_s->mmp_nodename, sizeof(mmp_s->mmp_nodename));
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#else
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strcpy(mmp_s->mmp_nodename, "unknown host");
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#endif
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strncpy(mmp_s->mmp_bdevname, fs->device_name,
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sizeof(mmp_s->mmp_bdevname));
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retval = ext2fs_mmp_write(fs, fs->super->s_mmp_block, fs->mmp_buf);
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if (retval)
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goto mmp_error;
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sleep(2 * mmp_check_interval + 1);
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retval = ext2fs_mmp_read(fs, fs->super->s_mmp_block, fs->mmp_buf);
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if (retval)
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goto mmp_error;
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if (seq != mmp_s->mmp_seq) {
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retval = EXT2_ET_MMP_FAILED;
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goto mmp_error;
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}
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mmp_s->mmp_seq = EXT4_MMP_SEQ_FSCK;
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retval = ext2fs_mmp_write(fs, fs->super->s_mmp_block, fs->mmp_buf);
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if (retval)
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goto mmp_error;
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return 0;
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mmp_error:
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return retval;
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}
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/*
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* Clear the MMP usage in the filesystem. If this function returns an
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* error EXT2_ET_MMP_CHANGE_ABORT it means the filesystem was modified
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* by some other process while in use, and changes should be dropped, or
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* risk filesystem corruption.
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*/
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errcode_t ext2fs_mmp_stop(ext2_filsys fs)
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{
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struct mmp_struct *mmp, *mmp_cmp;
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errcode_t retval = 0;
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if (!(fs->super->s_feature_incompat & EXT4_FEATURE_INCOMPAT_MMP) ||
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!(fs->flags & EXT2_FLAG_RW) || (fs->flags & EXT2_FLAG_SKIP_MMP))
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goto mmp_error;
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retval = ext2fs_mmp_read(fs, fs->super->s_mmp_block, fs->mmp_buf);
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if (retval)
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goto mmp_error;
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/* Check if the MMP block is not changed. */
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mmp = fs->mmp_buf;
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mmp_cmp = fs->mmp_cmp;
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if (memcmp(mmp, mmp_cmp, sizeof(*mmp_cmp))) {
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retval = EXT2_ET_MMP_CHANGE_ABORT;
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goto mmp_error;
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}
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mmp_cmp->mmp_seq = EXT4_MMP_SEQ_CLEAN;
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retval = ext2fs_mmp_write(fs, fs->super->s_mmp_block, fs->mmp_cmp);
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|
|
|
mmp_error:
|
|
|
|
if (fs->mmp_fd > 0) {
|
|
|
|
close(fs->mmp_fd);
|
|
|
|
fs->mmp_fd = -1;
|
|
|
|
}
|
|
|
|
|
|
|
|
return retval;
|
|
|
|
}
|
|
|
|
|
|
|
|
#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_update(ext2_filsys fs)
|
|
|
|
{
|
|
|
|
struct mmp_struct *mmp, *mmp_cmp;
|
|
|
|
struct timeval tv;
|
|
|
|
errcode_t retval = 0;
|
|
|
|
|
|
|
|
if (!(fs->super->s_feature_incompat & EXT4_FEATURE_INCOMPAT_MMP) ||
|
|
|
|
!(fs->flags & EXT2_FLAG_RW) || (fs->flags & EXT2_FLAG_SKIP_MMP))
|
|
|
|
return 0;
|
|
|
|
|
|
|
|
gettimeofday(&tv, 0);
|
|
|
|
if (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;
|
|
|
|
}
|