C++ UFS_SB函数代码示例

/*
 * NOTE! When we get the inode, we're the only people
 * that have access to it, and as such there are no
 * race conditions we have to worry about. The inode
 * is not on the hash-lists, and it cannot be reached
 * through the filesystem because the directory entry
 * has been deleted earlier.
 *
 * HOWEVER: we must make sure that we get no aliases,
 * which means that we have to call "clear_inode()"
 * _before_ we mark the inode not in use in the inode
 * bitmaps. Otherwise a newly created file might use
 * the same inode number (not actually the same pointer
 * though), and then we'd have two inodes sharing the
 * same inode number and space on the harddisk.
 */
void ufs_free_inode (struct inode * inode)
{
    struct super_block * sb;
    struct ufs_sb_private_info * uspi;
    struct ufs_super_block_first * usb1;
    struct ufs_cg_private_info * ucpi;
    struct ufs_cylinder_group * ucg;
    int is_directory;
    unsigned ino, cg, bit;
    
    UFSD("ENTER, ino %lu\n", inode->i_ino);

    sb = inode->i_sb;
    uspi = UFS_SB(sb)->s_uspi;
    usb1 = ubh_get_usb_first(uspi);
    
    ino = inode->i_ino;

    lock_super (sb);

    if (!((ino > 1) && (ino < (uspi->s_ncg * uspi->s_ipg )))) {
        ufs_warning(sb, "ufs_free_inode", "reserved inode or nonexistent inode %u\n", ino);
        unlock_super (sb);
        return;
    }
    
    cg = ufs_inotocg (ino);
    bit = ufs_inotocgoff (ino);
    ucpi = ufs_load_cylinder (sb, cg);
    if (!ucpi) {
        unlock_super (sb);
        return;
    }
    ucg = ubh_get_ucg(UCPI_UBH(ucpi));
    if (!ufs_cg_chkmagic(sb, ucg))
        ufs_panic (sb, "ufs_free_fragments", "internal error, bad cg magic number");

    ucg->cg_time = cpu_to_fs32(sb, get_seconds());

    is_directory = S_ISDIR(inode->i_mode);

    DQUOT_FREE_INODE(inode);
    DQUOT_DROP(inode);

    clear_inode (inode);

    if (ubh_isclr (UCPI_UBH(ucpi), ucpi->c_iusedoff, bit))
        ufs_error(sb, "ufs_free_inode", "bit already cleared for inode %u", ino);
    else {
        ubh_clrbit (UCPI_UBH(ucpi), ucpi->c_iusedoff, bit);
        if (ino < ucpi->c_irotor)
            ucpi->c_irotor = ino;
        fs32_add(sb, &ucg->cg_cs.cs_nifree, 1);
        uspi->cs_total.cs_nifree++;
        fs32_add(sb, &UFS_SB(sb)->fs_cs(cg).cs_nifree, 1);

        if (is_directory) {
            fs32_sub(sb, &ucg->cg_cs.cs_ndir, 1);
            uspi->cs_total.cs_ndir--;
            fs32_sub(sb, &UFS_SB(sb)->fs_cs(cg).cs_ndir, 1);
        }
    }

    ubh_mark_buffer_dirty (USPI_UBH(uspi));
    ubh_mark_buffer_dirty (UCPI_UBH(ucpi));
    if (sb->s_flags & MS_SYNCHRONOUS) {
        ubh_ll_rw_block(SWRITE, UCPI_UBH(ucpi));
        ubh_wait_on_buffer (UCPI_UBH(ucpi));
    }
    
    sb->s_dirt = 1;
    unlock_super (sb);
    UFSD("EXIT\n");
}

static u64 ufs_alloc_fragments(struct inode *inode, unsigned cgno,
			       u64 goal, unsigned count, int *err)
{
	struct super_block * sb;
	struct ufs_sb_private_info * uspi;
	struct ufs_super_block_first * usb1;
	struct ufs_cg_private_info * ucpi;
	struct ufs_cylinder_group * ucg;
	unsigned oldcg, i, j, k, allocsize;
	u64 result;
	
	UFSD("ENTER, ino %lu, cgno %u, goal %llu, count %u\n",
	     inode->i_ino, cgno, (unsigned long long)goal, count);

	sb = inode->i_sb;
	uspi = UFS_SB(sb)->s_uspi;
	usb1 = ubh_get_usb_first(uspi);
	oldcg = cgno;
	
	/*
	 * 1. searching on preferred cylinder group
	 */
	UFS_TEST_FREE_SPACE_CG

	/*
	 * 2. quadratic rehash
	 */
	for (j = 1; j < uspi->s_ncg; j *= 2) {
		cgno += j;
		if (cgno >= uspi->s_ncg) 
			cgno -= uspi->s_ncg;
		UFS_TEST_FREE_SPACE_CG
	}

	/*
	 * 3. brute force search
	 * We start at i = 2 ( 0 is checked at 1.step, 1 at 2.step )
	 */
	cgno = (oldcg + 1) % uspi->s_ncg;
	for (j = 2; j < uspi->s_ncg; j++) {
		cgno++;
		if (cgno >= uspi->s_ncg)
			cgno = 0;
		UFS_TEST_FREE_SPACE_CG
	}
	
	UFSD("EXIT (FAILED)\n");
	return 0;

cg_found:
	ucpi = ufs_load_cylinder (sb, cgno);
	if (!ucpi)
		return 0;
	ucg = ubh_get_ucg (UCPI_UBH(ucpi));
	if (!ufs_cg_chkmagic(sb, ucg)) 
		ufs_panic (sb, "ufs_alloc_fragments",
			"internal error, bad magic number on cg %u", cgno);
	ucg->cg_time = cpu_to_fs32(sb, get_seconds());

	if (count == uspi->s_fpb) {
		result = ufs_alloccg_block (inode, ucpi, goal, err);
		if (result == INVBLOCK)
			return 0;
		goto succed;
	}

	for (allocsize = count; allocsize < uspi->s_fpb; allocsize++)
		if (fs32_to_cpu(sb, ucg->cg_frsum[allocsize]) != 0)
			break;
	
	if (allocsize == uspi->s_fpb) {
		result = ufs_alloccg_block (inode, ucpi, goal, err);
		if (result == INVBLOCK)
			return 0;
		goal = ufs_dtogd(uspi, result);
		for (i = count; i < uspi->s_fpb; i++)
			ubh_setbit (UCPI_UBH(ucpi), ucpi->c_freeoff, goal + i);
		i = uspi->s_fpb - count;

		fs32_add(sb, &ucg->cg_cs.cs_nffree, i);
		uspi->cs_total.cs_nffree += i;
		fs32_add(sb, &UFS_SB(sb)->fs_cs(cgno).cs_nffree, i);
		fs32_add(sb, &ucg->cg_frsum[i], 1);
		goto succed;
	}

	result = ufs_bitmap_search (sb, ucpi, goal, allocsize);
	if (result == INVBLOCK)
		return 0;
	for (i = 0; i < count; i++)
		ubh_clrbit (UCPI_UBH(ucpi), ucpi->c_freeoff, result + i);
	
	fs32_sub(sb, &ucg->cg_cs.cs_nffree, count);
	uspi->cs_total.cs_nffree -= count;
	fs32_sub(sb, &UFS_SB(sb)->fs_cs(cgno).cs_nffree, count);
	fs32_sub(sb, &ucg->cg_frsum[allocsize], 1);

	if (count != allocsize)
		fs32_add(sb, &ucg->cg_frsum[allocsize - count], 1);

//.........这里部分代码省略.........

/*
 * There are two policies for allocating an inode.  If the new inode is
 * a directory, then a forward search is made for a block group with both
 * free space and a low directory-to-inode ratio; if that fails, then of
 * the groups with above-average free space, that group with the fewest
 * directories already is chosen.
 *
 * For other inodes, search forward from the parent directory's block
 * group to find a free inode.
 */
struct inode * ufs_new_inode(struct inode * dir, int mode)
{
    struct super_block * sb;
    struct ufs_sb_info * sbi;
    struct ufs_sb_private_info * uspi;
    struct ufs_super_block_first * usb1;
    struct ufs_cg_private_info * ucpi;
    struct ufs_cylinder_group * ucg;
    struct inode * inode;
    unsigned cg, bit, i, j, start;
    struct ufs_inode_info *ufsi;
    int err = -ENOSPC;

    UFSD("ENTER\n");
    
    /* Cannot create files in a deleted directory */
    if (!dir || !dir->i_nlink)
        return ERR_PTR(-EPERM);
    sb = dir->i_sb;
    inode = new_inode(sb);
    if (!inode)
        return ERR_PTR(-ENOMEM);
    ufsi = UFS_I(inode);
    sbi = UFS_SB(sb);
    uspi = sbi->s_uspi;
    usb1 = ubh_get_usb_first(uspi);

    lock_super (sb);

    /*
     * Try to place the inode in its parent directory
     */
    i = ufs_inotocg(dir->i_ino);
    if (sbi->fs_cs(i).cs_nifree) {
        cg = i;
        goto cg_found;
    }

    /*
     * Use a quadratic hash to find a group with a free inode
     */
    for ( j = 1; j < uspi->s_ncg; j <<= 1 ) {
        i += j;
        if (i >= uspi->s_ncg)
            i -= uspi->s_ncg;
        if (sbi->fs_cs(i).cs_nifree) {
            cg = i;
            goto cg_found;
        }
    }

    /*
     * That failed: try linear search for a free inode
     */
    i = ufs_inotocg(dir->i_ino) + 1;
    for (j = 2; j < uspi->s_ncg; j++) {
        i++;
        if (i >= uspi->s_ncg)
            i = 0;
        if (sbi->fs_cs(i).cs_nifree) {
            cg = i;
            goto cg_found;
        }
    }

    goto failed;

cg_found:
    ucpi = ufs_load_cylinder (sb, cg);
    if (!ucpi) {
        err = -EIO;
        goto failed;
    }
    ucg = ubh_get_ucg(UCPI_UBH(ucpi));
    if (!ufs_cg_chkmagic(sb, ucg)) 
        ufs_panic (sb, "ufs_new_inode", "internal error, bad cg magic number");

    start = ucpi->c_irotor;
    bit = ubh_find_next_zero_bit (UCPI_UBH(ucpi), ucpi->c_iusedoff, uspi->s_ipg, start);
    if (!(bit < uspi->s_ipg)) {
        bit = ubh_find_first_zero_bit (UCPI_UBH(ucpi), ucpi->c_iusedoff, start);
        if (!(bit < start)) {
            ufs_error (sb, "ufs_new_inode",
                "cylinder group %u corrupted - error in inode bitmap\n", cg);
            err = -EIO;
            goto failed;
        }
    }
    UFSD("start = %u, bit = %u, ipg = %u\n", start, bit, uspi->s_ipg);
    if (ubh_isclr (UCPI_UBH(ucpi), ucpi->c_iusedoff, bit))
//.........这里部分代码省略.........

static int ufs_trunc_indirect (struct inode * inode, unsigned offset, __fs32 *p)
{
    struct super_block * sb;
    struct ufs_sb_private_info * uspi;
    struct ufs_buffer_head * ind_ubh;
    __fs32 * ind;
    unsigned indirect_block, i, tmp;
    unsigned frag_to_free, free_count;
    int retry;

    UFSD("ENTER\n");

    sb = inode->i_sb;
    uspi = UFS_SB(sb)->s_uspi;

    frag_to_free = 0;
    free_count = 0;
    retry = 0;

    tmp = fs32_to_cpu(sb, *p);
    if (!tmp)
        return 0;
    ind_ubh = ubh_bread(sb, tmp, uspi->s_bsize);
    if (tmp != fs32_to_cpu(sb, *p)) {
        ubh_brelse (ind_ubh);
        return 1;
    }
    if (!ind_ubh) {
        *p = 0;
        return 0;
    }

    indirect_block = (DIRECT_BLOCK > offset) ? (DIRECT_BLOCK - offset) : 0;
    for (i = indirect_block; i < uspi->s_apb; i++) {
        ind = ubh_get_addr32 (ind_ubh, i);
        tmp = fs32_to_cpu(sb, *ind);
        if (!tmp)
            continue;

        *ind = 0;
        ubh_mark_buffer_dirty(ind_ubh);
        if (free_count == 0) {
            frag_to_free = tmp;
            free_count = uspi->s_fpb;
        } else if (free_count > 0 && frag_to_free == tmp - free_count)
            free_count += uspi->s_fpb;
        else {
            ufs_free_blocks (inode, frag_to_free, free_count);
            frag_to_free = tmp;
            free_count = uspi->s_fpb;
        }

        mark_inode_dirty(inode);
    }

    if (free_count > 0) {
        ufs_free_blocks (inode, frag_to_free, free_count);
    }
    for (i = 0; i < uspi->s_apb; i++)
        if (*ubh_get_addr32(ind_ubh,i))
            break;
    if (i >= uspi->s_apb) {
        tmp = fs32_to_cpu(sb, *p);
        *p = 0;

        ufs_free_blocks (inode, tmp, uspi->s_fpb);
        mark_inode_dirty(inode);
        ubh_bforget(ind_ubh);
        ind_ubh = NULL;
    }
    if (IS_SYNC(inode) && ind_ubh && ubh_buffer_dirty(ind_ubh)) {
        ubh_ll_rw_block(SWRITE, ind_ubh);
        ubh_wait_on_buffer (ind_ubh);
    }
    ubh_brelse (ind_ubh);

    UFSD("EXIT\n");

    return retry;
}

static u64 ufs_add_fragments(struct inode *inode, u64 fragment,
			     unsigned oldcount, unsigned newcount, int *err)
{
	struct super_block * sb;
	struct ufs_sb_private_info * uspi;
	struct ufs_super_block_first * usb1;
	struct ufs_cg_private_info * ucpi;
	struct ufs_cylinder_group * ucg;
	unsigned cgno, fragno, fragoff, count, fragsize, i;
	
	UFSD("ENTER, fragment %llu, oldcount %u, newcount %u\n",
	     (unsigned long long)fragment, oldcount, newcount);
	
	sb = inode->i_sb;
	uspi = UFS_SB(sb)->s_uspi;
	usb1 = ubh_get_usb_first (uspi);
	count = newcount - oldcount;
	
	cgno = ufs_dtog(uspi, fragment);
	if (fs32_to_cpu(sb, UFS_SB(sb)->fs_cs(cgno).cs_nffree) < count)
		return 0;
	if ((ufs_fragnum (fragment) + newcount) > uspi->s_fpb)
		return 0;
	ucpi = ufs_load_cylinder (sb, cgno);
	if (!ucpi)
		return 0;
	ucg = ubh_get_ucg (UCPI_UBH(ucpi));
	if (!ufs_cg_chkmagic(sb, ucg)) {
		ufs_panic (sb, "ufs_add_fragments",
			"internal error, bad magic number on cg %u", cgno);
		return 0;
	}

	fragno = ufs_dtogd(uspi, fragment);
	fragoff = ufs_fragnum (fragno);
	for (i = oldcount; i < newcount; i++)
		if (ubh_isclr (UCPI_UBH(ucpi), ucpi->c_freeoff, fragno + i))
			return 0;
	/*
	 * Block can be extended
	 */
	ucg->cg_time = cpu_to_fs32(sb, get_seconds());
	for (i = newcount; i < (uspi->s_fpb - fragoff); i++)
		if (ubh_isclr (UCPI_UBH(ucpi), ucpi->c_freeoff, fragno + i))
			break;
	fragsize = i - oldcount;
	if (!fs32_to_cpu(sb, ucg->cg_frsum[fragsize]))
		ufs_panic (sb, "ufs_add_fragments",
			"internal error or corrupted bitmap on cg %u", cgno);
	fs32_sub(sb, &ucg->cg_frsum[fragsize], 1);
	if (fragsize != count)
		fs32_add(sb, &ucg->cg_frsum[fragsize - count], 1);
	for (i = oldcount; i < newcount; i++)
		ubh_clrbit (UCPI_UBH(ucpi), ucpi->c_freeoff, fragno + i);

	fs32_sub(sb, &ucg->cg_cs.cs_nffree, count);
	fs32_sub(sb, &UFS_SB(sb)->fs_cs(cgno).cs_nffree, count);
	uspi->cs_total.cs_nffree -= count;
	
	ubh_mark_buffer_dirty (USPI_UBH(uspi));
	ubh_mark_buffer_dirty (UCPI_UBH(ucpi));
	if (sb->s_flags & MS_SYNCHRONOUS)
		ubh_sync_block(UCPI_UBH(ucpi));
	sb->s_dirt = 1;

	UFSD("EXIT, fragment %llu\n", (unsigned long long)fragment);
	
	return fragment;
}

static int ufs_remount (struct super_block *sb, int *mount_flags, char *data)
{
	struct ufs_sb_private_info * uspi;
	struct ufs_super_block_first * usb1;
	struct ufs_super_block_third * usb3;
	unsigned new_mount_opt, ufstype;
	unsigned flags;

	lock_ufs(sb);
	lock_super(sb);
	uspi = UFS_SB(sb)->s_uspi;
	flags = UFS_SB(sb)->s_flags;
	usb1 = ubh_get_usb_first(uspi);
	usb3 = ubh_get_usb_third(uspi);
	
	/*
	 * Allow the "check" option to be passed as a remount option.
	 * It is not possible to change ufstype option during remount
	 */
	ufstype = UFS_SB(sb)->s_mount_opt & UFS_MOUNT_UFSTYPE;
	new_mount_opt = 0;
	ufs_set_opt (new_mount_opt, ONERROR_LOCK);
	if (!ufs_parse_options (data, &new_mount_opt)) {
		unlock_super(sb);
		unlock_ufs(sb);
		return -EINVAL;
	}
	if (!(new_mount_opt & UFS_MOUNT_UFSTYPE)) {
		new_mount_opt |= ufstype;
	} else if ((new_mount_opt & UFS_MOUNT_UFSTYPE) != ufstype) {
		printk("ufstype can't be changed during remount\n");
		unlock_super(sb);
		unlock_ufs(sb);
		return -EINVAL;
	}

	if ((*mount_flags & MS_RDONLY) == (sb->s_flags & MS_RDONLY)) {
		UFS_SB(sb)->s_mount_opt = new_mount_opt;
		unlock_super(sb);
		unlock_ufs(sb);
		return 0;
	}
	
	/*
	 * fs was mouted as rw, remounting ro
	 */
	if (*mount_flags & MS_RDONLY) {
		ufs_put_super_internal(sb);
		usb1->fs_time = cpu_to_fs32(sb, get_seconds());
		if ((flags & UFS_ST_MASK) == UFS_ST_SUN
		  || (flags & UFS_ST_MASK) == UFS_ST_SUNOS
		  || (flags & UFS_ST_MASK) == UFS_ST_SUNx86) 
			ufs_set_fs_state(sb, usb1, usb3,
				UFS_FSOK - fs32_to_cpu(sb, usb1->fs_time));
		ubh_mark_buffer_dirty (USPI_UBH(uspi));
		sb->s_dirt = 0;
		sb->s_flags |= MS_RDONLY;
	} else {
	/*
	 * fs was mounted as ro, remounting rw
	 */
#ifndef CONFIG_UFS_FS_WRITE
		printk("ufs was compiled with read-only support, "
		"can't be mounted as read-write\n");
		unlock_super(sb);
		unlock_ufs(sb);
		return -EINVAL;
#else
		if (ufstype != UFS_MOUNT_UFSTYPE_SUN && 
		    ufstype != UFS_MOUNT_UFSTYPE_SUNOS &&
		    ufstype != UFS_MOUNT_UFSTYPE_44BSD &&
		    ufstype != UFS_MOUNT_UFSTYPE_SUNx86 &&
		    ufstype != UFS_MOUNT_UFSTYPE_UFS2) {
			printk("this ufstype is read-only supported\n");
			unlock_super(sb);
			unlock_ufs(sb);
			return -EINVAL;
		}
		if (!ufs_read_cylinder_structures(sb)) {
			printk("failed during remounting\n");
			unlock_super(sb);
			unlock_ufs(sb);
			return -EPERM;
		}
		sb->s_flags &= ~MS_RDONLY;
#endif
	}
	UFS_SB(sb)->s_mount_opt = new_mount_opt;
	unlock_super(sb);
	unlock_ufs(sb);
	return 0;
}

static int ufs_trunc_indirect(struct inode *inode, u64 offset, void *p)
{
	struct super_block * sb;
	struct ufs_sb_private_info * uspi;
	struct ufs_buffer_head * ind_ubh;
	void *ind;
	u64 tmp, indirect_block, i, frag_to_free;
	unsigned free_count;
	int retry;

	UFSD("ENTER: ino %lu, offset %llu, p: %p\n",
	     inode->i_ino, (unsigned long long)offset, p);

	BUG_ON(!p);
		
	sb = inode->i_sb;
	uspi = UFS_SB(sb)->s_uspi;

	frag_to_free = 0;
	free_count = 0;
	retry = 0;
	
	tmp = ufs_data_ptr_to_cpu(sb, p);
	if (!tmp)
		return 0;
	ind_ubh = ubh_bread(sb, tmp, uspi->s_bsize);
	if (tmp != ufs_data_ptr_to_cpu(sb, p)) {
		ubh_brelse (ind_ubh);
		return 1;
	}
	if (!ind_ubh) {
		ufs_data_ptr_clear(uspi, p);
		return 0;
	}

	indirect_block = (DIRECT_BLOCK > offset) ? (DIRECT_BLOCK - offset) : 0;
	for (i = indirect_block; i < uspi->s_apb; i++) {
		ind = ubh_get_data_ptr(uspi, ind_ubh, i);
		tmp = ufs_data_ptr_to_cpu(sb, ind);
		if (!tmp)
			continue;

		ufs_data_ptr_clear(uspi, ind);
		ubh_mark_buffer_dirty(ind_ubh);
		if (free_count == 0) {
			frag_to_free = tmp;
			free_count = uspi->s_fpb;
		} else if (free_count > 0 && frag_to_free == tmp - free_count)
			free_count += uspi->s_fpb;
		else {
			ufs_free_blocks (inode, frag_to_free, free_count);
			frag_to_free = tmp;
			free_count = uspi->s_fpb;
		}

		mark_inode_dirty(inode);
	}

	if (free_count > 0) {
		ufs_free_blocks (inode, frag_to_free, free_count);
	}
	for (i = 0; i < uspi->s_apb; i++)
		if (!ufs_is_data_ptr_zero(uspi,
					  ubh_get_data_ptr(uspi, ind_ubh, i)))
			break;
	if (i >= uspi->s_apb) {
		tmp = ufs_data_ptr_to_cpu(sb, p);
		ufs_data_ptr_clear(uspi, p);

		ufs_free_blocks (inode, tmp, uspi->s_fpb);
		mark_inode_dirty(inode);
		ubh_bforget(ind_ubh);
		ind_ubh = NULL;
	}
	if (IS_SYNC(inode) && ind_ubh && ubh_buffer_dirty(ind_ubh))
		ubh_sync_block(ind_ubh);
	ubh_brelse (ind_ubh);
	
	UFSD("EXIT: ino %lu\n", inode->i_ino);
	
	return retry;
}

static int ufs_alloc_lastblock(struct inode *inode)
{
	int err = 0;
	struct super_block *sb = inode->i_sb;
	struct address_space *mapping = inode->i_mapping;
	struct ufs_sb_private_info *uspi = UFS_SB(sb)->s_uspi;
	unsigned i, end;
	sector_t lastfrag;
	struct page *lastpage;
	struct buffer_head *bh;
	u64 phys64;

	lastfrag = (i_size_read(inode) + uspi->s_fsize - 1) >> uspi->s_fshift;

	if (!lastfrag)
		goto out;

	lastfrag--;

	lastpage = ufs_get_locked_page(mapping, lastfrag >>
				       (PAGE_CACHE_SHIFT - inode->i_blkbits));
       if (IS_ERR(lastpage)) {
               err = -EIO;
               goto out;
       }

       end = lastfrag & ((1 << (PAGE_CACHE_SHIFT - inode->i_blkbits)) - 1);
       bh = page_buffers(lastpage);
       for (i = 0; i < end; ++i)
               bh = bh->b_this_page;


       err = ufs_getfrag_block(inode, lastfrag, bh, 1);

       if (unlikely(err))
	       goto out_unlock;

       if (buffer_new(bh)) {
	       clear_buffer_new(bh);
	       unmap_underlying_metadata(bh->b_bdev,
					 bh->b_blocknr);
	       /*
		* we do not zeroize fragment, because of
		* if it maped to hole, it already contains zeroes
		*/
	       set_buffer_uptodate(bh);
	       mark_buffer_dirty(bh);
	       set_page_dirty(lastpage);
       }

       if (lastfrag >= UFS_IND_FRAGMENT) {
	       end = uspi->s_fpb - ufs_fragnum(lastfrag) - 1;
	       phys64 = bh->b_blocknr + 1;
	       for (i = 0; i < end; ++i) {
		       bh = sb_getblk(sb, i + phys64);
		       lock_buffer(bh);
		       memset(bh->b_data, 0, sb->s_blocksize);
		       set_buffer_uptodate(bh);
		       mark_buffer_dirty(bh);
		       unlock_buffer(bh);
		       sync_dirty_buffer(bh);
		       brelse(bh);
	       }
       }
out_unlock:
       ufs_put_locked_page(lastpage);
out:
       return err;
}

static int ufs_trunc_direct(struct inode *inode)
{
	struct ufs_inode_info *ufsi = UFS_I(inode);
	struct super_block * sb;
	struct ufs_sb_private_info * uspi;
	void *p;
	u64 frag1, frag2, frag3, frag4, block1, block2;
	unsigned frag_to_free, free_count;
	unsigned i, tmp;
	int retry;
	
	UFSD("ENTER: ino %lu\n", inode->i_ino);

	sb = inode->i_sb;
	uspi = UFS_SB(sb)->s_uspi;
	
	frag_to_free = 0;
	free_count = 0;
	retry = 0;
	
	frag1 = DIRECT_FRAGMENT;
	frag4 = min_t(u32, UFS_NDIR_FRAGMENT, ufsi->i_lastfrag);
	frag2 = ((frag1 & uspi->s_fpbmask) ? ((frag1 | uspi->s_fpbmask) + 1) : frag1);
	frag3 = frag4 & ~uspi->s_fpbmask;
	block1 = block2 = 0;
	if (frag2 > frag3) {
		frag2 = frag4;
		frag3 = frag4 = 0;
	} else if (frag2 < frag3) {
		block1 = ufs_fragstoblks (frag2);
		block2 = ufs_fragstoblks (frag3);
	}

	UFSD("ino %lu, frag1 %llu, frag2 %llu, block1 %llu, block2 %llu,"
	     " frag3 %llu, frag4 %llu\n", inode->i_ino,
	     (unsigned long long)frag1, (unsigned long long)frag2,
	     (unsigned long long)block1, (unsigned long long)block2,
	     (unsigned long long)frag3, (unsigned long long)frag4);

	if (frag1 >= frag2)
		goto next1;		

	/*
	 * Free first free fragments
	 */
	p = ufs_get_direct_data_ptr(uspi, ufsi, ufs_fragstoblks(frag1));
	tmp = ufs_data_ptr_to_cpu(sb, p);
	if (!tmp )
		ufs_panic (sb, "ufs_trunc_direct", "internal error");
	frag2 -= frag1;
	frag1 = ufs_fragnum (frag1);

	ufs_free_fragments(inode, tmp + frag1, frag2);
	mark_inode_dirty(inode);
	frag_to_free = tmp + frag1;

next1:
	/*
	 * Free whole blocks
	 */
	for (i = block1 ; i < block2; i++) {
		p = ufs_get_direct_data_ptr(uspi, ufsi, i);
		tmp = ufs_data_ptr_to_cpu(sb, p);
		if (!tmp)
			continue;
		ufs_data_ptr_clear(uspi, p);

		if (free_count == 0) {
			frag_to_free = tmp;
			free_count = uspi->s_fpb;
		} else if (free_count > 0 && frag_to_free == tmp - free_count)
			free_count += uspi->s_fpb;
		else {
			ufs_free_blocks (inode, frag_to_free, free_count);
			frag_to_free = tmp;
			free_count = uspi->s_fpb;
		}
		mark_inode_dirty(inode);
	}
	
	if (free_count > 0)
		ufs_free_blocks (inode, frag_to_free, free_count);

	if (frag3 >= frag4)
		goto next3;

	/*
	 * Free last free fragments
	 */
	p = ufs_get_direct_data_ptr(uspi, ufsi, ufs_fragstoblks(frag3));
	tmp = ufs_data_ptr_to_cpu(sb, p);
	if (!tmp )
		ufs_panic(sb, "ufs_truncate_direct", "internal error");
	frag4 = ufs_fragnum (frag4);
	ufs_data_ptr_clear(uspi, p);

	ufs_free_fragments (inode, tmp, frag4);
	mark_inode_dirty(inode);
 next3:

//.........这里部分代码省略.........

/*
 * Free 'count' fragments from fragment number 'fragment'
 */
void ufs_free_fragments(struct inode *inode, u64 fragment, unsigned count)
{
	struct super_block * sb;
	struct ufs_sb_private_info * uspi;
	struct ufs_cg_private_info * ucpi;
	struct ufs_cylinder_group * ucg;
	unsigned cgno, bit, end_bit, bbase, blkmap, i;
	u64 blkno;
	
	sb = inode->i_sb;
	uspi = UFS_SB(sb)->s_uspi;
	
	UFSD("ENTER, fragment %llu, count %u\n",
	     (unsigned long long)fragment, count);
	
	if (ufs_fragnum(fragment) + count > uspi->s_fpg)
		ufs_error (sb, "ufs_free_fragments", "internal error");

	mutex_lock(&UFS_SB(sb)->s_lock);
	
	cgno = ufs_dtog(uspi, fragment);
	bit = ufs_dtogd(uspi, fragment);
	if (cgno >= uspi->s_ncg) {
		ufs_panic (sb, "ufs_free_fragments", "freeing blocks are outside device");
		goto failed;
	}
		
	ucpi = ufs_load_cylinder (sb, cgno);
	if (!ucpi) 
		goto failed;
	ucg = ubh_get_ucg (UCPI_UBH(ucpi));
	if (!ufs_cg_chkmagic(sb, ucg)) {
		ufs_panic (sb, "ufs_free_fragments", "internal error, bad magic number on cg %u", cgno);
		goto failed;
	}

	end_bit = bit + count;
	bbase = ufs_blknum (bit);
	blkmap = ubh_blkmap (UCPI_UBH(ucpi), ucpi->c_freeoff, bbase);
	ufs_fragacct (sb, blkmap, ucg->cg_frsum, -1);
	for (i = bit; i < end_bit; i++) {
		if (ubh_isclr (UCPI_UBH(ucpi), ucpi->c_freeoff, i))
			ubh_setbit (UCPI_UBH(ucpi), ucpi->c_freeoff, i);
		else 
			ufs_error (sb, "ufs_free_fragments",
				   "bit already cleared for fragment %u", i);
	}
	
	fs32_add(sb, &ucg->cg_cs.cs_nffree, count);
	uspi->cs_total.cs_nffree += count;
	fs32_add(sb, &UFS_SB(sb)->fs_cs(cgno).cs_nffree, count);
	blkmap = ubh_blkmap (UCPI_UBH(ucpi), ucpi->c_freeoff, bbase);
	ufs_fragacct(sb, blkmap, ucg->cg_frsum, 1);

	/*
	 * Trying to reassemble free fragments into block
	 */
	blkno = ufs_fragstoblks (bbase);
	if (ubh_isblockset(UCPI_UBH(ucpi), ucpi->c_freeoff, blkno)) {
		fs32_sub(sb, &ucg->cg_cs.cs_nffree, uspi->s_fpb);
		uspi->cs_total.cs_nffree -= uspi->s_fpb;
		fs32_sub(sb, &UFS_SB(sb)->fs_cs(cgno).cs_nffree, uspi->s_fpb);
		if ((UFS_SB(sb)->s_flags & UFS_CG_MASK) == UFS_CG_44BSD)
			ufs_clusteracct (sb, ucpi, blkno, 1);
		fs32_add(sb, &ucg->cg_cs.cs_nbfree, 1);
		uspi->cs_total.cs_nbfree++;
		fs32_add(sb, &UFS_SB(sb)->fs_cs(cgno).cs_nbfree, 1);
		if (uspi->fs_magic != UFS2_MAGIC) {
			unsigned cylno = ufs_cbtocylno (bbase);

			fs16_add(sb, &ubh_cg_blks(ucpi, cylno,
						  ufs_cbtorpos(bbase)), 1);
			fs32_add(sb, &ubh_cg_blktot(ucpi, cylno), 1);
		}
	}
	
	ubh_mark_buffer_dirty (USPI_UBH(uspi));
	ubh_mark_buffer_dirty (UCPI_UBH(ucpi));
	if (sb->s_flags & MS_SYNCHRONOUS)
		ubh_sync_block(UCPI_UBH(ucpi));
	ufs_mark_sb_dirty(sb);

	mutex_unlock(&UFS_SB(sb)->s_lock);
	UFSD("EXIT\n");
	return;

failed:
	mutex_unlock(&UFS_SB(sb)->s_lock);
	UFSD("EXIT (FAILED)\n");
	return;
}

/*
 * Find cylinder group in cache and return it as pointer.
 * If cylinder group is not in cache, we will load it from disk.
 *
 * The cache is managed by LRU algorithm. 
 */
struct ufs_cg_private_info * ufs_load_cylinder (
	struct super_block * sb, unsigned cgno)
{
	struct ufs_sb_info * sbi = UFS_SB(sb);
	struct ufs_sb_private_info * uspi;
	struct ufs_cg_private_info * ucpi;
	unsigned cg, i, j;

	UFSD("ENTER, cgno %u\n", cgno);

	uspi = sbi->s_uspi;
	if (cgno >= uspi->s_ncg) {
		ufs_panic (sb, "ufs_load_cylinder", "internal error, high number of cg");
		return NULL;
	}
	/*
	 * Cylinder group number cg it in cache and it was last used
	 */
	if (sbi->s_cgno[0] == cgno) {
		UFSD("EXIT\n");
		return sbi->s_ucpi[0];
	}
	/*
	 * Number of cylinder groups is not higher than UFS_MAX_GROUP_LOADED
	 */
	if (uspi->s_ncg <= UFS_MAX_GROUP_LOADED) {
		if (sbi->s_cgno[cgno] != UFS_CGNO_EMPTY) {
			if (sbi->s_cgno[cgno] != cgno) {
				ufs_panic (sb, "ufs_load_cylinder", "internal error, wrong number of cg in cache");
				UFSD("EXIT (FAILED)\n");
				return NULL;
			}
			else {
				UFSD("EXIT\n");
				return sbi->s_ucpi[cgno];
			}
		} else {
			ufs_read_cylinder (sb, cgno, cgno);
			UFSD("EXIT\n");
			return sbi->s_ucpi[cgno];
		}
	}
	/*
	 * Cylinder group number cg is in cache but it was not last used, 
	 * we will move to the first position
	 */
	for (i = 0; i < sbi->s_cg_loaded && sbi->s_cgno[i] != cgno; i++);
	if (i < sbi->s_cg_loaded && sbi->s_cgno[i] == cgno) {
		cg = sbi->s_cgno[i];
		ucpi = sbi->s_ucpi[i];
		for (j = i; j > 0; j--) {
			sbi->s_cgno[j] = sbi->s_cgno[j-1];
			sbi->s_ucpi[j] = sbi->s_ucpi[j-1];
		}
		sbi->s_cgno[0] = cg;
		sbi->s_ucpi[0] = ucpi;
	/*
	 * Cylinder group number cg is not in cache, we will read it from disk
	 * and put it to the first position
	 */
	} else {
		if (sbi->s_cg_loaded < UFS_MAX_GROUP_LOADED)
			sbi->s_cg_loaded++;
		else
			ufs_put_cylinder (sb, UFS_MAX_GROUP_LOADED-1);
		ucpi = sbi->s_ucpi[sbi->s_cg_loaded - 1];
		for (j = sbi->s_cg_loaded - 1; j > 0; j--) {
			sbi->s_cgno[j] = sbi->s_cgno[j-1];
			sbi->s_ucpi[j] = sbi->s_ucpi[j-1];
		}
		sbi->s_ucpi[0] = ucpi;
		ufs_read_cylinder (sb, cgno, 0);
	}
	UFSD("EXIT\n");
	return sbi->s_ucpi[0];
}

/*
 * Free 'count' fragments from fragment number 'fragment' (free whole blocks)
 */
void ufs_free_blocks(struct inode *inode, u64 fragment, unsigned count)
{
	struct super_block * sb;
	struct ufs_sb_private_info * uspi;
	struct ufs_cg_private_info * ucpi;
	struct ufs_cylinder_group * ucg;
	unsigned overflow, cgno, bit, end_bit, i;
	u64 blkno;
	
	sb = inode->i_sb;
	uspi = UFS_SB(sb)->s_uspi;

	UFSD("ENTER, fragment %llu, count %u\n",
	     (unsigned long long)fragment, count);
	
	if ((fragment & uspi->s_fpbmask) || (count & uspi->s_fpbmask)) {
		ufs_error (sb, "ufs_free_blocks", "internal error, "
			   "fragment %llu, count %u\n",
			   (unsigned long long)fragment, count);
		goto failed;
	}

	mutex_lock(&UFS_SB(sb)->s_lock);
	
do_more:
	overflow = 0;
	cgno = ufs_dtog(uspi, fragment);
	bit = ufs_dtogd(uspi, fragment);
	if (cgno >= uspi->s_ncg) {
		ufs_panic (sb, "ufs_free_blocks", "freeing blocks are outside device");
		goto failed_unlock;
	}
	end_bit = bit + count;
	if (end_bit > uspi->s_fpg) {
		overflow = bit + count - uspi->s_fpg;
		count -= overflow;
		end_bit -= overflow;
	}

	ucpi = ufs_load_cylinder (sb, cgno);
	if (!ucpi) 
		goto failed_unlock;
	ucg = ubh_get_ucg (UCPI_UBH(ucpi));
	if (!ufs_cg_chkmagic(sb, ucg)) {
		ufs_panic (sb, "ufs_free_blocks", "internal error, bad magic number on cg %u", cgno);
		goto failed_unlock;
	}

	for (i = bit; i < end_bit; i += uspi->s_fpb) {
		blkno = ufs_fragstoblks(i);
		if (ubh_isblockset(UCPI_UBH(ucpi), ucpi->c_freeoff, blkno)) {
			ufs_error(sb, "ufs_free_blocks", "freeing free fragment");
		}
		ubh_setblock(UCPI_UBH(ucpi), ucpi->c_freeoff, blkno);
		if ((UFS_SB(sb)->s_flags & UFS_CG_MASK) == UFS_CG_44BSD)
			ufs_clusteracct (sb, ucpi, blkno, 1);

		fs32_add(sb, &ucg->cg_cs.cs_nbfree, 1);
		uspi->cs_total.cs_nbfree++;
		fs32_add(sb, &UFS_SB(sb)->fs_cs(cgno).cs_nbfree, 1);

		if (uspi->fs_magic != UFS2_MAGIC) {
			unsigned cylno = ufs_cbtocylno(i);

			fs16_add(sb, &ubh_cg_blks(ucpi, cylno,
						  ufs_cbtorpos(i)), 1);
			fs32_add(sb, &ubh_cg_blktot(ucpi, cylno), 1);
		}
	}

	ubh_mark_buffer_dirty (USPI_UBH(uspi));
	ubh_mark_buffer_dirty (UCPI_UBH(ucpi));
	if (sb->s_flags & MS_SYNCHRONOUS)
		ubh_sync_block(UCPI_UBH(ucpi));

	if (overflow) {
		fragment += count;
		count = overflow;
		goto do_more;
	}

	ufs_mark_sb_dirty(sb);
	mutex_unlock(&UFS_SB(sb)->s_lock);
	UFSD("EXIT\n");
	return;

failed_unlock:
	mutex_unlock(&UFS_SB(sb)->s_lock);
failed:
	UFSD("EXIT (FAILED)\n");
	return;
}

static u64 ufs_alloccg_block(struct inode *inode,
			     struct ufs_cg_private_info *ucpi,
			     u64 goal, int *err)
{
	struct super_block * sb;
	struct ufs_sb_private_info * uspi;
	struct ufs_super_block_first * usb1;
	struct ufs_cylinder_group * ucg;
	u64 result, blkno;

	UFSD("ENTER, goal %llu\n", (unsigned long long)goal);

	sb = inode->i_sb;
	uspi = UFS_SB(sb)->s_uspi;
	usb1 = ubh_get_usb_first(uspi);
	ucg = ubh_get_ucg(UCPI_UBH(ucpi));

	if (goal == 0) {
		goal = ucpi->c_rotor;
		goto norot;
	}
	goal = ufs_blknum (goal);
	goal = ufs_dtogd(uspi, goal);
	
	/*
	 * If the requested block is available, use it.
	 */
	if (ubh_isblockset(UCPI_UBH(ucpi), ucpi->c_freeoff, ufs_fragstoblks(goal))) {
		result = goal;
		goto gotit;
	}
	
norot:	
	result = ufs_bitmap_search (sb, ucpi, goal, uspi->s_fpb);
	if (result == INVBLOCK)
		return INVBLOCK;
	ucpi->c_rotor = result;
gotit:
	blkno = ufs_fragstoblks(result);
	ubh_clrblock (UCPI_UBH(ucpi), ucpi->c_freeoff, blkno);
	if ((UFS_SB(sb)->s_flags & UFS_CG_MASK) == UFS_CG_44BSD)
		ufs_clusteracct (sb, ucpi, blkno, -1);
	if(DQUOT_ALLOC_BLOCK(inode, uspi->s_fpb)) {
		*err = -EDQUOT;
		return INVBLOCK;
	}

	fs32_sub(sb, &ucg->cg_cs.cs_nbfree, 1);
	uspi->cs_total.cs_nbfree--;
	fs32_sub(sb, &UFS_SB(sb)->fs_cs(ucpi->c_cgx).cs_nbfree, 1);

	if (uspi->fs_magic != UFS2_MAGIC) {
		unsigned cylno = ufs_cbtocylno((unsigned)result);

		fs16_sub(sb, &ubh_cg_blks(ucpi, cylno,
					  ufs_cbtorpos((unsigned)result)), 1);
		fs32_sub(sb, &ubh_cg_blktot(ucpi, cylno), 1);
	}
	
	UFSD("EXIT, result %llu\n", (unsigned long long)result);

	return result;
}

static int ufs_trunc_dindirect (struct inode *inode, unsigned offset, __fs32 *p)
{
    struct super_block * sb;
    struct ufs_sb_private_info * uspi;
    struct ufs_buffer_head * dind_bh;
    unsigned i, tmp, dindirect_block;
    __fs32 * dind;
    int retry = 0;

    UFSD("ENTER\n");

    sb = inode->i_sb;
    uspi = UFS_SB(sb)->s_uspi;

    dindirect_block = (DIRECT_BLOCK > offset)
                      ? ((DIRECT_BLOCK - offset) >> uspi->s_apbshift) : 0;
    retry = 0;

    tmp = fs32_to_cpu(sb, *p);
    if (!tmp)
        return 0;
    dind_bh = ubh_bread(sb, tmp, uspi->s_bsize);
    if (tmp != fs32_to_cpu(sb, *p)) {
        ubh_brelse (dind_bh);
        return 1;
    }
    if (!dind_bh) {
        *p = 0;
        return 0;
    }

    for (i = dindirect_block ; i < uspi->s_apb ; i++) {
        dind = ubh_get_addr32 (dind_bh, i);
        tmp = fs32_to_cpu(sb, *dind);
        if (!tmp)
            continue;
        retry |= ufs_trunc_indirect (inode, offset + (i << uspi->s_apbshift), dind);
        ubh_mark_buffer_dirty(dind_bh);
    }

    for (i = 0; i < uspi->s_apb; i++)
        if (*ubh_get_addr32 (dind_bh, i))
            break;
    if (i >= uspi->s_apb) {
        tmp = fs32_to_cpu(sb, *p);
        *p = 0;

        ufs_free_blocks(inode, tmp, uspi->s_fpb);
        mark_inode_dirty(inode);
        ubh_bforget(dind_bh);
        dind_bh = NULL;
    }
    if (IS_SYNC(inode) && dind_bh && ubh_buffer_dirty(dind_bh)) {
        ubh_ll_rw_block(SWRITE, dind_bh);
        ubh_wait_on_buffer (dind_bh);
    }
    ubh_brelse (dind_bh);

    UFSD("EXIT\n");

    return retry;
}

/*
 * Free 'count' fragments from fragment number 'fragment' (free whole blocks)
 */
void ufs_free_blocks (struct inode * inode, unsigned fragment, unsigned count) {
	struct super_block * sb;
	struct ufs_sb_private_info * uspi;
	struct ufs_super_block_first * usb1;
	struct ufs_cg_private_info * ucpi;
	struct ufs_cylinder_group * ucg;
	unsigned overflow, cgno, bit, end_bit, blkno, i, cylno;
	
	sb = inode->i_sb;
	uspi = UFS_SB(sb)->s_uspi;
	usb1 = ubh_get_usb_first(USPI_UBH);

	UFSD(("ENTER, fragment %u, count %u\n", fragment, count))
	
	if ((fragment & uspi->s_fpbmask) || (count & uspi->s_fpbmask)) {
		ufs_error (sb, "ufs_free_blocks", "internal error, "
			"fragment %u, count %u\n", fragment, count);
		goto failed;
	}

	lock_super(sb);
	
do_more:
	overflow = 0;
	cgno = ufs_dtog (fragment);
	bit = ufs_dtogd (fragment);
	if (cgno >= uspi->s_ncg) {
		ufs_panic (sb, "ufs_free_blocks", "freeing blocks are outside device");
		goto failed;
	}
	end_bit = bit + count;
	if (end_bit > uspi->s_fpg) {
		overflow = bit + count - uspi->s_fpg;
		count -= overflow;
		end_bit -= overflow;
	}

	ucpi = ufs_load_cylinder (sb, cgno);
	if (!ucpi) 
		goto failed;
	ucg = ubh_get_ucg (UCPI_UBH);
	if (!ufs_cg_chkmagic(sb, ucg)) {
		ufs_panic (sb, "ufs_free_blocks", "internal error, bad magic number on cg %u", cgno);
		goto failed;
	}

	for (i = bit; i < end_bit; i += uspi->s_fpb) {
		blkno = ufs_fragstoblks(i);
		if (ubh_isblockset(UCPI_UBH, ucpi->c_freeoff, blkno)) {
			ufs_error(sb, "ufs_free_blocks", "freeing free fragment");
		}
		ubh_setblock(UCPI_UBH, ucpi->c_freeoff, blkno);
		if ((UFS_SB(sb)->s_flags & UFS_CG_MASK) == UFS_CG_44BSD)
			ufs_clusteracct (sb, ucpi, blkno, 1);
		DQUOT_FREE_BLOCK(inode, uspi->s_fpb);

		fs32_add(sb, &ucg->cg_cs.cs_nbfree, 1);
		fs32_add(sb, &usb1->fs_cstotal.cs_nbfree, 1);
		fs32_add(sb, &UFS_SB(sb)->fs_cs(cgno).cs_nbfree, 1);
		cylno = ufs_cbtocylno(i);
		fs16_add(sb, &ubh_cg_blks(ucpi, cylno, ufs_cbtorpos(i)), 1);
		fs32_add(sb, &ubh_cg_blktot(ucpi, cylno), 1);
	}

	ubh_mark_buffer_dirty (USPI_UBH);
	ubh_mark_buffer_dirty (UCPI_UBH);
	if (sb->s_flags & MS_SYNCHRONOUS) {
		ubh_wait_on_buffer (UCPI_UBH);
		ubh_ll_rw_block (WRITE, 1, (struct ufs_buffer_head **)&ucpi);
		ubh_wait_on_buffer (UCPI_UBH);
	}

	if (overflow) {
		fragment += count;
		count = overflow;
		goto do_more;
	}

	sb->s_dirt = 1;
	unlock_super (sb);
	UFSD(("EXIT\n"))
	return;

failed:
	unlock_super (sb);
	UFSD(("EXIT (FAILED)\n"))
	return;
}