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Sourcecode: e2fsprogs version File versions

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;
}

int ext2fs_super_and_bgd_loc(ext2_filsys fs, 
                       dgrp_t group,
                       blk_t *ret_super_blk,
                       blk_t *ret_old_desc_blk,
                       blk_t *ret_new_desc_blk,
                       int *ret_meta_bg)
{
      blk_t group_block, super_blk = 0, old_desc_blk = 0, new_desc_blk = 0;
      unsigned int meta_bg, meta_bg_size;
      int   numblocks, has_super;
      int   old_desc_blocks;

      group_block = fs->super->s_first_data_block +
            (group * fs->super->s_blocks_per_group);

      if (fs->super->s_feature_incompat & EXT2_FEATURE_INCOMPAT_META_BG)
            old_desc_blocks = fs->super->s_first_meta_bg;
      else
            old_desc_blocks = 
                  fs->desc_blocks + fs->super->s_reserved_gdt_blocks;

      if (group == fs->group_desc_count-1) {
            numblocks = (fs->super->s_blocks_count -
                       fs->super->s_first_data_block) %
                  fs->super->s_blocks_per_group;
            if (!numblocks)
                  numblocks = fs->super->s_blocks_per_group;
      } else
            numblocks = fs->super->s_blocks_per_group;

      has_super = ext2fs_bg_has_super(fs, group);

      if (has_super) {
            super_blk = group_block;
            numblocks--;
      }
      meta_bg_size = (fs->blocksize / sizeof (struct ext2_group_desc));
      meta_bg = group / meta_bg_size;

      if (!(fs->super->s_feature_incompat & EXT2_FEATURE_INCOMPAT_META_BG) ||
          (meta_bg < fs->super->s_first_meta_bg)) {
            if (has_super) {
                  old_desc_blk = group_block + 1;
                  numblocks -= old_desc_blocks;
            }
      } else {
            if (((group % meta_bg_size) == 0) ||
                ((group % meta_bg_size) == 1) ||
                ((group % meta_bg_size) == (meta_bg_size-1))) {
                  if (has_super)
                        has_super = 1;
                  new_desc_blk = group_block + has_super;
                  numblocks--;
            }
      }
            
      numblocks -= 2 + fs->inode_blocks_per_group;

      if (ret_super_blk)
            *ret_super_blk = super_blk;
      if (ret_old_desc_blk)
            *ret_old_desc_blk = old_desc_blk;
      if (ret_new_desc_blk)
            *ret_new_desc_blk = new_desc_blk;
      if (ret_meta_bg)
            *ret_meta_bg = meta_bg;
      return (numblocks);
}


/*
 * 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 */
}

static errcode_t write_backup_super(ext2_filsys fs, dgrp_t group,
                            blk_t group_block,
                            struct ext2_super_block *super_shadow)
{
      dgrp_t      sgrp = group;
      
      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;

      return io_channel_write_blk(fs->io, group_block, -SUPERBLOCK_SIZE, 
                            super_shadow);
}


errcode_t ext2fs_flush(ext2_filsys fs)
{
      dgrp_t            i,j;
      blk_t       group_block;
      errcode_t   retval;
      unsigned long     fs_state;
      struct ext2_super_block *super_shadow = 0;
      struct ext2_group_desc *group_shadow = 0;
      struct ext2_group_desc *s, *t;
      char  *group_ptr;
      int   old_desc_blocks;
      
      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, &super_shadow);
            if (retval)
                  goto errout;
            retval = ext2fs_get_mem((size_t)(fs->blocksize *
                                     fs->desc_blocks),
                              &group_shadow);
            if (retval)
                  goto errout;
            memset(group_shadow, 0, (size_t) fs->blocksize *
                   fs->desc_blocks);

            /* 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
      
      /*
       * 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)
            goto write_primary_superblock_only;

      /*
       * Set the state of the FS to be non-valid.  (The state has
       * already been backed up earlier, and will be restored after
       * we write out the backup superblocks.)
       */
      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;
      group_ptr = (char *) group_shadow;
      if (fs->super->s_feature_incompat & EXT2_FEATURE_INCOMPAT_META_BG)
            old_desc_blocks = fs->super->s_first_meta_bg;
      else
            old_desc_blocks = fs->desc_blocks;

      for (i = 0; i < fs->group_desc_count; i++) {
            blk_t super_blk, old_desc_blk, new_desc_blk;
            int   meta_bg;

            ext2fs_super_and_bgd_loc(fs, i, &super_blk, &old_desc_blk, 
                               &new_desc_blk, &meta_bg);

            if (!(fs->flags & EXT2_FLAG_MASTER_SB_ONLY) &&i && super_blk) {
                  retval = write_backup_super(fs, i, super_blk,
                                        super_shadow);
                  if (retval)
                        goto errout;
            }
            if (fs->flags & EXT2_FLAG_SUPER_ONLY)
                  continue;
            if ((old_desc_blk) && 
                (!(fs->flags & EXT2_FLAG_MASTER_SB_ONLY) || (i == 0))) {
                  retval = io_channel_write_blk(fs->io,
                        old_desc_blk, old_desc_blocks, group_ptr);
                  if (retval)
                        goto errout;
            }
            if (new_desc_blk) {
                  retval = io_channel_write_blk(fs->io, new_desc_blk,
                        1, group_ptr + (meta_bg*fs->blocksize));
                  if (retval)
                        goto errout;
            }
      }
      fs->super->s_block_group_nr = 0;
      fs->super->s_state = fs_state;
#ifdef EXT2FS_ENABLE_SWAPFS
      if (fs->flags & EXT2_FLAG_SWAP_BYTES) {
            *super_shadow = *fs->super;
            ext2fs_swap_super(super_shadow);
      }
#endif

      /*
       * 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;
      }

write_primary_superblock_only:
      /*
       * Write out master superblock.  This has to be done
       * separately, since it is located at a fixed location
       * (SUPERBLOCK_OFFSET).  We flush all other pending changes
       * out to disk first, just to avoid a race condition with an
       * insy-tinsy window....
       */
      retval = io_channel_flush(fs->io);
      retval = write_primary_superblock(fs, super_shadow);
      if (retval)
            goto errout;

      fs->flags &= ~EXT2_FLAG_DIRTY;

      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(&super_shadow);
            if (group_shadow)
                  ext2fs_free_mem(&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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