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logfile.c

/*
 * logfile.c - NTFS kernel journal handling. Part of the Linux-NTFS project.
 *
 * Copyright (c) 2002-2007 Anton Altaparmakov
 *
 * This program/include file is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as published
 * by the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program/include file is distributed in the hope that it will be
 * useful, but WITHOUT ANY WARRANTY; without even the implied warranty
 * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program (in the main directory of the Linux-NTFS
 * distribution in the file COPYING); if not, write to the Free Software
 * Foundation,Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

#ifdef NTFS_RW

#include <linux/types.h>
#include <linux/fs.h>
#include <linux/highmem.h>
#include <linux/buffer_head.h>
#include <linux/bitops.h>

#include "attrib.h"
#include "aops.h"
#include "debug.h"
#include "logfile.h"
#include "malloc.h"
#include "volume.h"
#include "ntfs.h"

/**
 * ntfs_check_restart_page_header - check the page header for consistency
 * @vi:           $LogFile inode to which the restart page header belongs
 * @rp:           restart page header to check
 * @pos:    position in @vi at which the restart page header resides
 *
 * Check the restart page header @rp for consistency and return 'true' if it is
 * consistent and 'false' otherwise.
 *
 * This function only needs NTFS_BLOCK_SIZE bytes in @rp, i.e. it does not
 * require the full restart page.
 */
static bool ntfs_check_restart_page_header(struct inode *vi,
            RESTART_PAGE_HEADER *rp, s64 pos)
{
      u32 logfile_system_page_size, logfile_log_page_size;
      u16 ra_ofs, usa_count, usa_ofs, usa_end = 0;
      bool have_usa = true;

      ntfs_debug("Entering.");
      /*
       * If the system or log page sizes are smaller than the ntfs block size
       * or either is not a power of 2 we cannot handle this log file.
       */
      logfile_system_page_size = le32_to_cpu(rp->system_page_size);
      logfile_log_page_size = le32_to_cpu(rp->log_page_size);
      if (logfile_system_page_size < NTFS_BLOCK_SIZE ||
                  logfile_log_page_size < NTFS_BLOCK_SIZE ||
                  logfile_system_page_size &
                  (logfile_system_page_size - 1) ||
                  logfile_log_page_size & (logfile_log_page_size - 1)) {
            ntfs_error(vi->i_sb, "$LogFile uses unsupported page size.");
            return false;
      }
      /*
       * We must be either at !pos (1st restart page) or at pos = system page
       * size (2nd restart page).
       */
      if (pos && pos != logfile_system_page_size) {
            ntfs_error(vi->i_sb, "Found restart area in incorrect "
                        "position in $LogFile.");
            return false;
      }
      /* We only know how to handle version 1.1. */
      if (sle16_to_cpu(rp->major_ver) != 1 ||
                  sle16_to_cpu(rp->minor_ver) != 1) {
            ntfs_error(vi->i_sb, "$LogFile version %i.%i is not "
                        "supported.  (This driver supports version "
                        "1.1 only.)", (int)sle16_to_cpu(rp->major_ver),
                        (int)sle16_to_cpu(rp->minor_ver));
            return false;
      }
      /*
       * If chkdsk has been run the restart page may not be protected by an
       * update sequence array.
       */
      if (ntfs_is_chkd_record(rp->magic) && !le16_to_cpu(rp->usa_count)) {
            have_usa = false;
            goto skip_usa_checks;
      }
      /* Verify the size of the update sequence array. */
      usa_count = 1 + (logfile_system_page_size >> NTFS_BLOCK_SIZE_BITS);
      if (usa_count != le16_to_cpu(rp->usa_count)) {
            ntfs_error(vi->i_sb, "$LogFile restart page specifies "
                        "inconsistent update sequence array count.");
            return false;
      }
      /* Verify the position of the update sequence array. */
      usa_ofs = le16_to_cpu(rp->usa_ofs);
      usa_end = usa_ofs + usa_count * sizeof(u16);
      if (usa_ofs < sizeof(RESTART_PAGE_HEADER) ||
                  usa_end > NTFS_BLOCK_SIZE - sizeof(u16)) {
            ntfs_error(vi->i_sb, "$LogFile restart page specifies "
                        "inconsistent update sequence array offset.");
            return false;
      }
skip_usa_checks:
      /*
       * Verify the position of the restart area.  It must be:
       *    - aligned to 8-byte boundary,
       *    - after the update sequence array, and
       *    - within the system page size.
       */
      ra_ofs = le16_to_cpu(rp->restart_area_offset);
      if (ra_ofs & 7 || (have_usa ? ra_ofs < usa_end :
                  ra_ofs < sizeof(RESTART_PAGE_HEADER)) ||
                  ra_ofs > logfile_system_page_size) {
            ntfs_error(vi->i_sb, "$LogFile restart page specifies "
                        "inconsistent restart area offset.");
            return false;
      }
      /*
       * Only restart pages modified by chkdsk are allowed to have chkdsk_lsn
       * set.
       */
      if (!ntfs_is_chkd_record(rp->magic) && sle64_to_cpu(rp->chkdsk_lsn)) {
            ntfs_error(vi->i_sb, "$LogFile restart page is not modified "
                        "by chkdsk but a chkdsk LSN is specified.");
            return false;
      }
      ntfs_debug("Done.");
      return true;
}

/**
 * ntfs_check_restart_area - check the restart area for consistency
 * @vi:           $LogFile inode to which the restart page belongs
 * @rp:           restart page whose restart area to check
 *
 * Check the restart area of the restart page @rp for consistency and return
 * 'true' if it is consistent and 'false' otherwise.
 *
 * This function assumes that the restart page header has already been
 * consistency checked.
 *
 * This function only needs NTFS_BLOCK_SIZE bytes in @rp, i.e. it does not
 * require the full restart page.
 */
static bool ntfs_check_restart_area(struct inode *vi, RESTART_PAGE_HEADER *rp)
{
      u64 file_size;
      RESTART_AREA *ra;
      u16 ra_ofs, ra_len, ca_ofs;
      u8 fs_bits;

      ntfs_debug("Entering.");
      ra_ofs = le16_to_cpu(rp->restart_area_offset);
      ra = (RESTART_AREA*)((u8*)rp + ra_ofs);
      /*
       * Everything before ra->file_size must be before the first word
       * protected by an update sequence number.  This ensures that it is
       * safe to access ra->client_array_offset.
       */
      if (ra_ofs + offsetof(RESTART_AREA, file_size) >
                  NTFS_BLOCK_SIZE - sizeof(u16)) {
            ntfs_error(vi->i_sb, "$LogFile restart area specifies "
                        "inconsistent file offset.");
            return false;
      }
      /*
       * Now that we can access ra->client_array_offset, make sure everything
       * up to the log client array is before the first word protected by an
       * update sequence number.  This ensures we can access all of the
       * restart area elements safely.  Also, the client array offset must be
       * aligned to an 8-byte boundary.
       */
      ca_ofs = le16_to_cpu(ra->client_array_offset);
      if (((ca_ofs + 7) & ~7) != ca_ofs ||
                  ra_ofs + ca_ofs > NTFS_BLOCK_SIZE - sizeof(u16)) {
            ntfs_error(vi->i_sb, "$LogFile restart area specifies "
                        "inconsistent client array offset.");
            return false;
      }
      /*
       * The restart area must end within the system page size both when
       * calculated manually and as specified by ra->restart_area_length.
       * Also, the calculated length must not exceed the specified length.
       */
      ra_len = ca_ofs + le16_to_cpu(ra->log_clients) *
                  sizeof(LOG_CLIENT_RECORD);
      if (ra_ofs + ra_len > le32_to_cpu(rp->system_page_size) ||
                  ra_ofs + le16_to_cpu(ra->restart_area_length) >
                  le32_to_cpu(rp->system_page_size) ||
                  ra_len > le16_to_cpu(ra->restart_area_length)) {
            ntfs_error(vi->i_sb, "$LogFile restart area is out of bounds "
                        "of the system page size specified by the "
                        "restart page header and/or the specified "
                        "restart area length is inconsistent.");
            return false;
      }
      /*
       * The ra->client_free_list and ra->client_in_use_list must be either
       * LOGFILE_NO_CLIENT or less than ra->log_clients or they are
       * overflowing the client array.
       */
      if ((ra->client_free_list != LOGFILE_NO_CLIENT &&
                  le16_to_cpu(ra->client_free_list) >=
                  le16_to_cpu(ra->log_clients)) ||
                  (ra->client_in_use_list != LOGFILE_NO_CLIENT &&
                  le16_to_cpu(ra->client_in_use_list) >=
                  le16_to_cpu(ra->log_clients))) {
            ntfs_error(vi->i_sb, "$LogFile restart area specifies "
                        "overflowing client free and/or in use lists.");
            return false;
      }
      /*
       * Check ra->seq_number_bits against ra->file_size for consistency.
       * We cannot just use ffs() because the file size is not a power of 2.
       */
      file_size = (u64)sle64_to_cpu(ra->file_size);
      fs_bits = 0;
      while (file_size) {
            file_size >>= 1;
            fs_bits++;
      }
      if (le32_to_cpu(ra->seq_number_bits) != 67 - fs_bits) {
            ntfs_error(vi->i_sb, "$LogFile restart area specifies "
                        "inconsistent sequence number bits.");
            return false;
      }
      /* The log record header length must be a multiple of 8. */
      if (((le16_to_cpu(ra->log_record_header_length) + 7) & ~7) !=
                  le16_to_cpu(ra->log_record_header_length)) {
            ntfs_error(vi->i_sb, "$LogFile restart area specifies "
                        "inconsistent log record header length.");
            return false;
      }
      /* Dito for the log page data offset. */
      if (((le16_to_cpu(ra->log_page_data_offset) + 7) & ~7) !=
                  le16_to_cpu(ra->log_page_data_offset)) {
            ntfs_error(vi->i_sb, "$LogFile restart area specifies "
                        "inconsistent log page data offset.");
            return false;
      }
      ntfs_debug("Done.");
      return true;
}

/**
 * ntfs_check_log_client_array - check the log client array for consistency
 * @vi:           $LogFile inode to which the restart page belongs
 * @rp:           restart page whose log client array to check
 *
 * Check the log client array of the restart page @rp for consistency and
 * return 'true' if it is consistent and 'false' otherwise.
 *
 * This function assumes that the restart page header and the restart area have
 * already been consistency checked.
 *
 * Unlike ntfs_check_restart_page_header() and ntfs_check_restart_area(), this
 * function needs @rp->system_page_size bytes in @rp, i.e. it requires the full
 * restart page and the page must be multi sector transfer deprotected.
 */
static bool ntfs_check_log_client_array(struct inode *vi,
            RESTART_PAGE_HEADER *rp)
{
      RESTART_AREA *ra;
      LOG_CLIENT_RECORD *ca, *cr;
      u16 nr_clients, idx;
      bool in_free_list, idx_is_first;

      ntfs_debug("Entering.");
      ra = (RESTART_AREA*)((u8*)rp + le16_to_cpu(rp->restart_area_offset));
      ca = (LOG_CLIENT_RECORD*)((u8*)ra +
                  le16_to_cpu(ra->client_array_offset));
      /*
       * Check the ra->client_free_list first and then check the
       * ra->client_in_use_list.  Check each of the log client records in
       * each of the lists and check that the array does not overflow the
       * ra->log_clients value.  Also keep track of the number of records
       * visited as there cannot be more than ra->log_clients records and
       * that way we detect eventual loops in within a list.
       */
      nr_clients = le16_to_cpu(ra->log_clients);
      idx = le16_to_cpu(ra->client_free_list);
      in_free_list = true;
check_list:
      for (idx_is_first = true; idx != LOGFILE_NO_CLIENT_CPU; nr_clients--,
                  idx = le16_to_cpu(cr->next_client)) {
            if (!nr_clients || idx >= le16_to_cpu(ra->log_clients))
                  goto err_out;
            /* Set @cr to the current log client record. */
            cr = ca + idx;
            /* The first log client record must not have a prev_client. */
            if (idx_is_first) {
                  if (cr->prev_client != LOGFILE_NO_CLIENT)
                        goto err_out;
                  idx_is_first = false;
            }
      }
      /* Switch to and check the in use list if we just did the free list. */
      if (in_free_list) {
            in_free_list = false;
            idx = le16_to_cpu(ra->client_in_use_list);
            goto check_list;
      }
      ntfs_debug("Done.");
      return true;
err_out:
      ntfs_error(vi->i_sb, "$LogFile log client array is corrupt.");
      return false;
}

/**
 * ntfs_check_and_load_restart_page - check the restart page for consistency
 * @vi:           $LogFile inode to which the restart page belongs
 * @rp:           restart page to check
 * @pos:    position in @vi at which the restart page resides
 * @wrp:    [OUT] copy of the multi sector transfer deprotected restart page
 * @lsn:    [OUT] set to the current logfile lsn on success
 *
 * Check the restart page @rp for consistency and return 0 if it is consistent
 * and -errno otherwise.  The restart page may have been modified by chkdsk in
 * which case its magic is CHKD instead of RSTR.
 *
 * This function only needs NTFS_BLOCK_SIZE bytes in @rp, i.e. it does not
 * require the full restart page.
 *
 * If @wrp is not NULL, on success, *@wrp will point to a buffer containing a
 * copy of the complete multi sector transfer deprotected page.  On failure,
 * *@wrp is undefined.
 *
 * Simillarly, if @lsn is not NULL, on succes *@lsn will be set to the current
 * logfile lsn according to this restart page.  On failure, *@lsn is undefined.
 *
 * The following error codes are defined:
 *    -EINVAL     - The restart page is inconsistent.
 *    -ENOMEM     - Not enough memory to load the restart page.
 *    -EIO  - Failed to reading from $LogFile.
 */
static int ntfs_check_and_load_restart_page(struct inode *vi,
            RESTART_PAGE_HEADER *rp, s64 pos, RESTART_PAGE_HEADER **wrp,
            LSN *lsn)
{
      RESTART_AREA *ra;
      RESTART_PAGE_HEADER *trp;
      int size, err;

      ntfs_debug("Entering.");
      /* Check the restart page header for consistency. */
      if (!ntfs_check_restart_page_header(vi, rp, pos)) {
            /* Error output already done inside the function. */
            return -EINVAL;
      }
      /* Check the restart area for consistency. */
      if (!ntfs_check_restart_area(vi, rp)) {
            /* Error output already done inside the function. */
            return -EINVAL;
      }
      ra = (RESTART_AREA*)((u8*)rp + le16_to_cpu(rp->restart_area_offset));
      /*
       * Allocate a buffer to store the whole restart page so we can multi
       * sector transfer deprotect it.
       */
      trp = ntfs_malloc_nofs(le32_to_cpu(rp->system_page_size));
      if (!trp) {
            ntfs_error(vi->i_sb, "Failed to allocate memory for $LogFile "
                        "restart page buffer.");
            return -ENOMEM;
      }
      /*
       * Read the whole of the restart page into the buffer.  If it fits
       * completely inside @rp, just copy it from there.  Otherwise map all
       * the required pages and copy the data from them.
       */
      size = PAGE_CACHE_SIZE - (pos & ~PAGE_CACHE_MASK);
      if (size >= le32_to_cpu(rp->system_page_size)) {
            memcpy(trp, rp, le32_to_cpu(rp->system_page_size));
      } else {
            pgoff_t idx;
            struct page *page;
            int have_read, to_read;

            /* First copy what we already have in @rp. */
            memcpy(trp, rp, size);
            /* Copy the remaining data one page at a time. */
            have_read = size;
            to_read = le32_to_cpu(rp->system_page_size) - size;
            idx = (pos + size) >> PAGE_CACHE_SHIFT;
            BUG_ON((pos + size) & ~PAGE_CACHE_MASK);
            do {
                  page = ntfs_map_page(vi->i_mapping, idx);
                  if (IS_ERR(page)) {
                        ntfs_error(vi->i_sb, "Error mapping $LogFile "
                                    "page (index %lu).", idx);
                        err = PTR_ERR(page);
                        if (err != -EIO && err != -ENOMEM)
                              err = -EIO;
                        goto err_out;
                  }
                  size = min_t(int, to_read, PAGE_CACHE_SIZE);
                  memcpy((u8*)trp + have_read, page_address(page), size);
                  ntfs_unmap_page(page);
                  have_read += size;
                  to_read -= size;
                  idx++;
            } while (to_read > 0);
      }
      /*
       * Perform the multi sector transfer deprotection on the buffer if the
       * restart page is protected.
       */
      if ((!ntfs_is_chkd_record(trp->magic) || le16_to_cpu(trp->usa_count))
                  && post_read_mst_fixup((NTFS_RECORD*)trp,
                  le32_to_cpu(rp->system_page_size))) {
            /*
             * A multi sector tranfer error was detected.  We only need to
             * abort if the restart page contents exceed the multi sector
             * transfer fixup of the first sector.
             */
            if (le16_to_cpu(rp->restart_area_offset) +
                        le16_to_cpu(ra->restart_area_length) >
                        NTFS_BLOCK_SIZE - sizeof(u16)) {
                  ntfs_error(vi->i_sb, "Multi sector transfer error "
                              "detected in $LogFile restart page.");
                  err = -EINVAL;
                  goto err_out;
            }
      }
      /*
       * If the restart page is modified by chkdsk or there are no active
       * logfile clients, the logfile is consistent.  Otherwise, need to
       * check the log client records for consistency, too.
       */
      err = 0;
      if (ntfs_is_rstr_record(rp->magic) &&
                  ra->client_in_use_list != LOGFILE_NO_CLIENT) {
            if (!ntfs_check_log_client_array(vi, trp)) {
                  err = -EINVAL;
                  goto err_out;
            }
      }
      if (lsn) {
            if (ntfs_is_rstr_record(rp->magic))
                  *lsn = sle64_to_cpu(ra->current_lsn);
            else /* if (ntfs_is_chkd_record(rp->magic)) */
                  *lsn = sle64_to_cpu(rp->chkdsk_lsn);
      }
      ntfs_debug("Done.");
      if (wrp)
            *wrp = trp;
      else {
err_out:
            ntfs_free(trp);
      }
      return err;
}

/**
 * ntfs_check_logfile - check the journal for consistency
 * @log_vi: struct inode of loaded journal $LogFile to check
 * @rp:           [OUT] on success this is a copy of the current restart page
 *
 * Check the $LogFile journal for consistency and return 'true' if it is
 * consistent and 'false' if not.  On success, the current restart page is
 * returned in *@rp.  Caller must call ntfs_free(*@rp) when finished with it.
 *
 * At present we only check the two restart pages and ignore the log record
 * pages.
 *
 * Note that the MstProtected flag is not set on the $LogFile inode and hence
 * when reading pages they are not deprotected.  This is because we do not know
 * if the $LogFile was created on a system with a different page size to ours
 * yet and mst deprotection would fail if our page size is smaller.
 */
bool ntfs_check_logfile(struct inode *log_vi, RESTART_PAGE_HEADER **rp)
{
      s64 size, pos;
      LSN rstr1_lsn, rstr2_lsn;
      ntfs_volume *vol = NTFS_SB(log_vi->i_sb);
      struct address_space *mapping = log_vi->i_mapping;
      struct page *page = NULL;
      u8 *kaddr = NULL;
      RESTART_PAGE_HEADER *rstr1_ph = NULL;
      RESTART_PAGE_HEADER *rstr2_ph = NULL;
      int log_page_size, log_page_mask, err;
      bool logfile_is_empty = true;
      u8 log_page_bits;

      ntfs_debug("Entering.");
      /* An empty $LogFile must have been clean before it got emptied. */
      if (NVolLogFileEmpty(vol))
            goto is_empty;
      size = i_size_read(log_vi);
      /* Make sure the file doesn't exceed the maximum allowed size. */
      if (size > MaxLogFileSize)
            size = MaxLogFileSize;
      /*
       * Truncate size to a multiple of the page cache size or the default
       * log page size if the page cache size is between the default log page
       * log page size if the page cache size is between the default log page
       * size and twice that.
       */
      if (PAGE_CACHE_SIZE >= DefaultLogPageSize && PAGE_CACHE_SIZE <=
                  DefaultLogPageSize * 2)
            log_page_size = DefaultLogPageSize;
      else
            log_page_size = PAGE_CACHE_SIZE;
      log_page_mask = log_page_size - 1;
      /*
       * Use ntfs_ffs() instead of ffs() to enable the compiler to
       * optimize log_page_size and log_page_bits into constants.
       */
      log_page_bits = ntfs_ffs(log_page_size) - 1;
      size &= ~(s64)(log_page_size - 1);
      /*
       * Ensure the log file is big enough to store at least the two restart
       * pages and the minimum number of log record pages.
       */
      if (size < log_page_size * 2 || (size - log_page_size * 2) >>
                  log_page_bits < MinLogRecordPages) {
            ntfs_error(vol->sb, "$LogFile is too small.");
            return false;
      }
      /*
       * Read through the file looking for a restart page.  Since the restart
       * page header is at the beginning of a page we only need to search at
       * what could be the beginning of a page (for each page size) rather
       * than scanning the whole file byte by byte.  If all potential places
       * contain empty and uninitialzed records, the log file can be assumed
       * to be empty.
       */
      for (pos = 0; pos < size; pos <<= 1) {
            pgoff_t idx = pos >> PAGE_CACHE_SHIFT;
            if (!page || page->index != idx) {
                  if (page)
                        ntfs_unmap_page(page);
                  page = ntfs_map_page(mapping, idx);
                  if (IS_ERR(page)) {
                        ntfs_error(vol->sb, "Error mapping $LogFile "
                                    "page (index %lu).", idx);
                        goto err_out;
                  }
            }
            kaddr = (u8*)page_address(page) + (pos & ~PAGE_CACHE_MASK);
            /*
             * A non-empty block means the logfile is not empty while an
             * empty block after a non-empty block has been encountered
             * means we are done.
             */
            if (!ntfs_is_empty_recordp((le32*)kaddr))
                  logfile_is_empty = false;
            else if (!logfile_is_empty)
                  break;
            /*
             * A log record page means there cannot be a restart page after
             * this so no need to continue searching.
             */
            if (ntfs_is_rcrd_recordp((le32*)kaddr))
                  break;
            /* If not a (modified by chkdsk) restart page, continue. */
            if (!ntfs_is_rstr_recordp((le32*)kaddr) &&
                        !ntfs_is_chkd_recordp((le32*)kaddr)) {
                  if (!pos)
                        pos = NTFS_BLOCK_SIZE >> 1;
                  continue;
            }
            /*
             * Check the (modified by chkdsk) restart page for consistency
             * and get a copy of the complete multi sector transfer
             * deprotected restart page.
             */
            err = ntfs_check_and_load_restart_page(log_vi,
                        (RESTART_PAGE_HEADER*)kaddr, pos,
                        !rstr1_ph ? &rstr1_ph : &rstr2_ph,
                        !rstr1_ph ? &rstr1_lsn : &rstr2_lsn);
            if (!err) {
                  /*
                   * If we have now found the first (modified by chkdsk)
                   * restart page, continue looking for the second one.
                   */
                  if (!pos) {
                        pos = NTFS_BLOCK_SIZE >> 1;
                        continue;
                  }
                  /*
                   * We have now found the second (modified by chkdsk)
                   * restart page, so we can stop looking.
                   */
                  break;
            }
            /*
             * Error output already done inside the function.  Note, we do
             * not abort if the restart page was invalid as we might still
             * find a valid one further in the file.
             */
            if (err != -EINVAL) {
                  ntfs_unmap_page(page);
                  goto err_out;
            }
            /* Continue looking. */
            if (!pos)
                  pos = NTFS_BLOCK_SIZE >> 1;
      }
      if (page)
            ntfs_unmap_page(page);
      if (logfile_is_empty) {
            NVolSetLogFileEmpty(vol);
is_empty:
            ntfs_debug("Done.  ($LogFile is empty.)");
            return true;
      }
      if (!rstr1_ph) {
            BUG_ON(rstr2_ph);
            ntfs_error(vol->sb, "Did not find any restart pages in "
                        "$LogFile and it was not empty.");
            return false;
      }
      /* If both restart pages were found, use the more recent one. */
      if (rstr2_ph) {
            /*
             * If the second restart area is more recent, switch to it.
             * Otherwise just throw it away.
             */
            if (rstr2_lsn > rstr1_lsn) {
                  ntfs_debug("Using second restart page as it is more "
                              "recent.");
                  ntfs_free(rstr1_ph);
                  rstr1_ph = rstr2_ph;
                  /* rstr1_lsn = rstr2_lsn; */
            } else {
                  ntfs_debug("Using first restart page as it is more "
                              "recent.");
                  ntfs_free(rstr2_ph);
            }
            rstr2_ph = NULL;
      }
      /* All consistency checks passed. */
      if (rp)
            *rp = rstr1_ph;
      else
            ntfs_free(rstr1_ph);
      ntfs_debug("Done.");
      return true;
err_out:
      if (rstr1_ph)
            ntfs_free(rstr1_ph);
      return false;
}

/**
 * ntfs_is_logfile_clean - check in the journal if the volume is clean
 * @log_vi: struct inode of loaded journal $LogFile to check
 * @rp:           copy of the current restart page
 *
 * Analyze the $LogFile journal and return 'true' if it indicates the volume was
 * shutdown cleanly and 'false' if not.
 *
 * At present we only look at the two restart pages and ignore the log record
 * pages.  This is a little bit crude in that there will be a very small number
 * of cases where we think that a volume is dirty when in fact it is clean.
 * This should only affect volumes that have not been shutdown cleanly but did
 * not have any pending, non-check-pointed i/o, i.e. they were completely idle
 * at least for the five seconds preceeding the unclean shutdown.
 *
 * This function assumes that the $LogFile journal has already been consistency
 * checked by a call to ntfs_check_logfile() and in particular if the $LogFile
 * is empty this function requires that NVolLogFileEmpty() is true otherwise an
 * empty volume will be reported as dirty.
 */
bool ntfs_is_logfile_clean(struct inode *log_vi, const RESTART_PAGE_HEADER *rp)
{
      ntfs_volume *vol = NTFS_SB(log_vi->i_sb);
      RESTART_AREA *ra;

      ntfs_debug("Entering.");
      /* An empty $LogFile must have been clean before it got emptied. */
      if (NVolLogFileEmpty(vol)) {
            ntfs_debug("Done.  ($LogFile is empty.)");
            return true;
      }
      BUG_ON(!rp);
      if (!ntfs_is_rstr_record(rp->magic) &&
                  !ntfs_is_chkd_record(rp->magic)) {
            ntfs_error(vol->sb, "Restart page buffer is invalid.  This is "
                        "probably a bug in that the $LogFile should "
                        "have been consistency checked before calling "
                        "this function.");
            return false;
      }
      ra = (RESTART_AREA*)((u8*)rp + le16_to_cpu(rp->restart_area_offset));
      /*
       * If the $LogFile has active clients, i.e. it is open, and we do not
       * have the RESTART_VOLUME_IS_CLEAN bit set in the restart area flags,
       * we assume there was an unclean shutdown.
       */
      if (ra->client_in_use_list != LOGFILE_NO_CLIENT &&
                  !(ra->flags & RESTART_VOLUME_IS_CLEAN)) {
            ntfs_debug("Done.  $LogFile indicates a dirty shutdown.");
            return false;
      }
      /* $LogFile indicates a clean shutdown. */
      ntfs_debug("Done.  $LogFile indicates a clean shutdown.");
      return true;
}

/**
 * ntfs_empty_logfile - empty the contents of the $LogFile journal
 * @log_vi: struct inode of loaded journal $LogFile to empty
 *
 * Empty the contents of the $LogFile journal @log_vi and return 'true' on
 * success and 'false' on error.
 *
 * This function assumes that the $LogFile journal has already been consistency
 * checked by a call to ntfs_check_logfile() and that ntfs_is_logfile_clean()
 * has been used to ensure that the $LogFile is clean.
 */
bool ntfs_empty_logfile(struct inode *log_vi)
{
      VCN vcn, end_vcn;
      ntfs_inode *log_ni = NTFS_I(log_vi);
      ntfs_volume *vol = log_ni->vol;
      struct super_block *sb = vol->sb;
      runlist_element *rl;
      unsigned long flags;
      unsigned block_size, block_size_bits;
      int err;
      bool should_wait = true;

      ntfs_debug("Entering.");
      if (NVolLogFileEmpty(vol)) {
            ntfs_debug("Done.");
            return true;
      }
      /*
       * We cannot use ntfs_attr_set() because we may be still in the middle
       * of a mount operation.  Thus we do the emptying by hand by first
       * zapping the page cache pages for the $LogFile/$DATA attribute and
       * then emptying each of the buffers in each of the clusters specified
       * by the runlist by hand.
       */
      block_size = sb->s_blocksize;
      block_size_bits = sb->s_blocksize_bits;
      vcn = 0;
      read_lock_irqsave(&log_ni->size_lock, flags);
      end_vcn = (log_ni->initialized_size + vol->cluster_size_mask) >>
                  vol->cluster_size_bits;
      read_unlock_irqrestore(&log_ni->size_lock, flags);
      truncate_inode_pages(log_vi->i_mapping, 0);
      down_write(&log_ni->runlist.lock);
      rl = log_ni->runlist.rl;
      if (unlikely(!rl || vcn < rl->vcn || !rl->length)) {
map_vcn:
            err = ntfs_map_runlist_nolock(log_ni, vcn, NULL);
            if (err) {
                  ntfs_error(sb, "Failed to map runlist fragment (error "
                              "%d).", -err);
                  goto err;
            }
            rl = log_ni->runlist.rl;
            BUG_ON(!rl || vcn < rl->vcn || !rl->length);
      }
      /* Seek to the runlist element containing @vcn. */
      while (rl->length && vcn >= rl[1].vcn)
            rl++;
      do {
            LCN lcn;
            sector_t block, end_block;
            s64 len;

            /*
             * If this run is not mapped map it now and start again as the
             * runlist will have been updated.
             */
            lcn = rl->lcn;
            if (unlikely(lcn == LCN_RL_NOT_MAPPED)) {
                  vcn = rl->vcn;
                  goto map_vcn;
            }
            /* If this run is not valid abort with an error. */
            if (unlikely(!rl->length || lcn < LCN_HOLE))
                  goto rl_err;
            /* Skip holes. */
            if (lcn == LCN_HOLE)
                  continue;
            block = lcn << vol->cluster_size_bits >> block_size_bits;
            len = rl->length;
            if (rl[1].vcn > end_vcn)
                  len = end_vcn - rl->vcn;
            end_block = (lcn + len) << vol->cluster_size_bits >>
                        block_size_bits;
            /* Iterate over the blocks in the run and empty them. */
            do {
                  struct buffer_head *bh;

                  /* Obtain the buffer, possibly not uptodate. */
                  bh = sb_getblk(sb, block);
                  BUG_ON(!bh);
                  /* Setup buffer i/o submission. */
                  lock_buffer(bh);
                  bh->b_end_io = end_buffer_write_sync;
                  get_bh(bh);
                  /* Set the entire contents of the buffer to 0xff. */
                  memset(bh->b_data, -1, block_size);
                  if (!buffer_uptodate(bh))
                        set_buffer_uptodate(bh);
                  if (buffer_dirty(bh))
                        clear_buffer_dirty(bh);
                  /*
                   * Submit the buffer and wait for i/o to complete but
                   * only for the first buffer so we do not miss really
                   * serious i/o errors.  Once the first buffer has
                   * completed ignore errors afterwards as we can assume
                   * that if one buffer worked all of them will work.
                   */
                  submit_bh(WRITE, bh);
                  if (should_wait) {
                        should_wait = false;
                        wait_on_buffer(bh);
                        if (unlikely(!buffer_uptodate(bh)))
                              goto io_err;
                  }
                  brelse(bh);
            } while (++block < end_block);
      } while ((++rl)->vcn < end_vcn);
      up_write(&log_ni->runlist.lock);
      /*
       * Zap the pages again just in case any got instantiated whilst we were
       * emptying the blocks by hand.  FIXME: We may not have completed
       * writing to all the buffer heads yet so this may happen too early.
       * We really should use a kernel thread to do the emptying
       * asynchronously and then we can also set the volume dirty and output
       * an error message if emptying should fail.
       */
      truncate_inode_pages(log_vi->i_mapping, 0);
      /* Set the flag so we do not have to do it again on remount. */
      NVolSetLogFileEmpty(vol);
      ntfs_debug("Done.");
      return true;
io_err:
      ntfs_error(sb, "Failed to write buffer.  Unmount and run chkdsk.");
      goto dirty_err;
rl_err:
      ntfs_error(sb, "Runlist is corrupt.  Unmount and run chkdsk.");
dirty_err:
      NVolSetErrors(vol);
      err = -EIO;
err:
      up_write(&log_ni->runlist.lock);
      ntfs_error(sb, "Failed to fill $LogFile with 0xff bytes (error %d).",
                  -err);
      return false;
}

#endif /* NTFS_RW */

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