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closefs.c

/*
 * closefs.c --- close an ext2 filesystem
 * 
 * Copyright (C) 1993, 1994, 1995, 1996 Theodore Ts'o.
 *
 * %Begin-Header%
 * This file may be redistributed under the terms of the GNU Public
 * License.
 * %End-Header%
 */

#include <stdio.h>
#if HAVE_UNISTD_H
#include <unistd.h>
#endif
#include <time.h>
#include <string.h>

#include "ext2_fs.h"
#include "ext2fsP.h"

static int test_root(int a, int b)
{
      if (a == 0)
            return 1;
      while (1) {
            if (a == 1)
                  return 1;
            if (a % b)
                  return 0;
            a = a / b;
      }
}

int ext2fs_bg_has_super(ext2_filsys fs, int group_block)
{
      if (!(fs->super->s_feature_ro_compat &
            EXT2_FEATURE_RO_COMPAT_SPARSE_SUPER))
            return 1;

      if (test_root(group_block, 3) || (test_root(group_block, 5)) ||
          test_root(group_block, 7))
            return 1;
      
      return 0;
}

/*
 * This function forces out the primary superblock.  We need to only
 * write out those fields which we have changed, since if the
 * filesystem is mounted, it may have changed some of the other
 * fields.
 *
 * It takes as input a superblock which has already been byte swapped
 * (if necessary).
 *
 */
static errcode_t write_primary_superblock(ext2_filsys fs,
                                struct ext2_super_block *super)
{
      __u16       *old_super, *new_super;
      int         check_idx, write_idx, size;
      errcode_t   retval;

      if (!fs->io->manager->write_byte || !fs->orig_super) {
            io_channel_set_blksize(fs->io, SUPERBLOCK_OFFSET);
            retval = io_channel_write_blk(fs->io, 1, -SUPERBLOCK_SIZE,
                                    super);
            io_channel_set_blksize(fs->io, fs->blocksize);
            return retval;
      }

      old_super = (__u16 *) fs->orig_super;
      new_super = (__u16 *) super;

      for (check_idx = 0; check_idx < SUPERBLOCK_SIZE/2; check_idx++) {
            if (old_super[check_idx] == new_super[check_idx])
                  continue;
            write_idx = check_idx;
            for (check_idx++; check_idx < SUPERBLOCK_SIZE/2; check_idx++)
                  if (old_super[check_idx] == new_super[check_idx])
                        break;
            size = 2 * (check_idx - write_idx);
#if 0
            printf("Writing %d bytes starting at %d\n",
                   size, write_idx*2);
#endif
            retval = io_channel_write_byte(fs->io,
                         SUPERBLOCK_OFFSET + (2 * write_idx), size,
                                     new_super + write_idx);
            if (retval)
                  return retval;
      }
      memcpy(fs->orig_super, super, SUPERBLOCK_SIZE);
      return 0;
}


/*
 * Updates the revision to EXT2_DYNAMIC_REV
 */
void ext2fs_update_dynamic_rev(ext2_filsys fs)
{
      struct ext2_super_block *sb = fs->super;

      if (sb->s_rev_level > EXT2_GOOD_OLD_REV)
            return;

      sb->s_rev_level = EXT2_DYNAMIC_REV;
      sb->s_first_ino = EXT2_GOOD_OLD_FIRST_INO;
      sb->s_inode_size = EXT2_GOOD_OLD_INODE_SIZE;
      /* s_uuid is handled by e2fsck already */
      /* other fields should be left alone */
}

errcode_t ext2fs_flush(ext2_filsys fs)
{
      dgrp_t            i,j,maxgroup,sgrp;
      blk_t       group_block;
      errcode_t   retval;
      char        *group_ptr;
      unsigned long     fs_state;
      struct ext2_super_block *super_shadow = 0;
      struct ext2_group_desc *group_shadow = 0;
      struct ext2_group_desc *s, *t;
      
      EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);

      fs_state = fs->super->s_state;

      fs->super->s_wtime = time(NULL);
      fs->super->s_block_group_nr = 0;
#ifdef EXT2FS_ENABLE_SWAPFS
      if (fs->flags & EXT2_FLAG_SWAP_BYTES) {
            retval = EXT2_ET_NO_MEMORY;
            retval = ext2fs_get_mem(SUPERBLOCK_SIZE,
                              (void **) &super_shadow);
            if (retval)
                  goto errout;
            retval = ext2fs_get_mem((size_t)(fs->blocksize *
                                     fs->desc_blocks),
                              (void **) &group_shadow);
            if (retval)
                  goto errout;
            memset(group_shadow, 0, (size_t) fs->blocksize *
                   fs->desc_blocks);

            /* swap the superblock */
            *super_shadow = *fs->super;
            ext2fs_swap_super(super_shadow);

            /* swap the group descriptors */
            for (j=0, s=fs->group_desc, t=group_shadow;
                 j < fs->group_desc_count; j++, t++, s++) {
                  *t = *s;
                  ext2fs_swap_group_desc(t);
            }
      } else {
            super_shadow = fs->super;
            group_shadow = fs->group_desc;
      }
#else
      super_shadow = fs->super;
      group_shadow = fs->group_desc;
#endif
      
      /*
       * Write out master superblock.  This has to be done
       * separately, since it is located at a fixed location
       * (SUPERBLOCK_OFFSET).
       */
      retval = write_primary_superblock(fs, super_shadow);
      if (retval)
            goto errout;

      /*
       * If this is an external journal device, don't write out the
       * block group descriptors or any of the backup superblocks
       */
      if (fs->super->s_feature_incompat &
          EXT3_FEATURE_INCOMPAT_JOURNAL_DEV) {
            retval = 0;
            goto errout;
      }

      /*
       * Set the state of the FS to be non-valid.  (The state has
       * already been backed up earlier, and will be restored when
       * we exit.)
       */
      fs->super->s_state &= ~EXT2_VALID_FS;
#ifdef EXT2FS_ENABLE_SWAPFS
      if (fs->flags & EXT2_FLAG_SWAP_BYTES) {
            *super_shadow = *fs->super;
            ext2fs_swap_super(super_shadow);
      }
#endif

      /*
       * Write out the master group descriptors, and the backup
       * superblocks and group descriptors.
       */
      group_block = fs->super->s_first_data_block;
      maxgroup = (fs->flags & EXT2_FLAG_MASTER_SB_ONLY) ? 1 :
            fs->group_desc_count;
      for (i = 0; i < maxgroup; i++) {
            if (!ext2fs_bg_has_super(fs, i))
                  goto next_group;

            sgrp = i;
            if (sgrp > ((1 << 16) - 1))
                  sgrp = (1 << 16) - 1;
#ifdef EXT2FS_ENABLE_SWAPFS
            if (fs->flags & EXT2_FLAG_SWAP_BYTES)
                  super_shadow->s_block_group_nr = ext2fs_swab16(sgrp);
            else
#endif
                  fs->super->s_block_group_nr = sgrp;

            if (i !=0 ) {
                  retval = io_channel_write_blk(fs->io, group_block,
                                          -SUPERBLOCK_SIZE,
                                          super_shadow);
                  if (retval)
                        goto errout;
            }
            if (fs->flags & EXT2_FLAG_SUPER_ONLY)
                  goto next_group;
            group_ptr = (char *) group_shadow;
            for (j=0; j < fs->desc_blocks; j++) {
                  retval = io_channel_write_blk(fs->io,
                                          group_block+1+j, 1,
                                          group_ptr);
                  if (retval)
                        goto errout;
                  group_ptr += fs->blocksize;
            }
      next_group:
            group_block += EXT2_BLOCKS_PER_GROUP(fs->super);
      }
      fs->super->s_block_group_nr = 0;

      /*
       * If the write_bitmaps() function is present, call it to
       * flush the bitmaps.  This is done this way so that a simple
       * program that doesn't mess with the bitmaps doesn't need to
       * drag in the bitmaps.c code.
       */
      if (fs->write_bitmaps) {
            retval = fs->write_bitmaps(fs);
            if (retval)
                  goto errout;
      }

      fs->flags &= ~EXT2_FLAG_DIRTY;

      /*
       * Flush the blocks out to disk
       */
      retval = io_channel_flush(fs->io);
errout:
      fs->super->s_state = fs_state;
      if (fs->flags & EXT2_FLAG_SWAP_BYTES) {
            if (super_shadow)
                  ext2fs_free_mem((void **) &super_shadow);
            if (group_shadow)
                  ext2fs_free_mem((void **) &group_shadow);
      }
      return retval;
}

errcode_t ext2fs_close(ext2_filsys fs)
{
      errcode_t   retval;
      
      EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);

      if (fs->flags & EXT2_FLAG_DIRTY) {
            retval = ext2fs_flush(fs);
            if (retval)
                  return retval;
      }
      if (fs->write_bitmaps) {
            retval = fs->write_bitmaps(fs);
            if (retval)
                  return retval;
      }
      ext2fs_free(fs);
      return 0;
}


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