namei.c

嵌入式系统设计与实例开发实验教材二源码 多线程应用程序设计 串行端口程序设计 AD接口实验 CAN总线通信实验 GPS通信实验 Linux内核移植与编译实验 IC卡读写实验 SD驱动使

    /* copy name */
    memcpy ((char *)(deh + 1), name, namelen);
    /* padd by 0s to the 4 byte boundary */
    padd_item ((char *)(deh + 1), ROUND_UP (namelen), namelen);

    /* entry is ready to be pasted into tree, set 'visibility' and 'stat data in entry' attributes */
    mark_de_without_sd (deh);
    visible ? mark_de_visible (deh) : mark_de_hidden (deh);

    /* find the proper place for the new entry */
    memset (bit_string, 0, sizeof (bit_string));
    de.de_gen_number_bit_string = (char *)bit_string;
    retval = reiserfs_find_entry (dir, name, namelen, &path, &de);
    if( retval != NAME_NOT_FOUND ) {
	if (buffer != small_buf)
	    reiserfs_kfree (buffer, buflen, dir->i_sb);
	pathrelse (&path);

        if (retval != NAME_FOUND) {
	    reiserfs_warning ("zam-7002:" __FUNCTION__ ": \"reiserfs_find_entry\" has returned"
                              " unexpected value (%d)\n", retval);
       }

	return -EEXIST;
    }

    gen_number = find_first_zero_bit (bit_string, MAX_GENERATION_NUMBER + 1);
    if (gen_number > MAX_GENERATION_NUMBER) {
      /* there is no free generation number */
      reiserfs_warning ("reiserfs_add_entry: Congratulations! we have got hash function screwed up\n");
      if (buffer != small_buf)
          reiserfs_kfree (buffer, buflen, dir->i_sb);
      pathrelse (&path);
      return -EBUSY;
    }
    /* adjust offset of directory enrty */
    put_deh_offset(deh, SET_GENERATION_NUMBER(deh_offset(deh), gen_number));
    set_cpu_key_k_offset (&entry_key, deh_offset(deh));
 
    /* update max-hash-collisions counter in reiserfs_sb_info */
    PROC_INFO_MAX( th -> t_super, max_hash_collisions, gen_number );
 		  
    if (gen_number != 0) {	/* we need to re-search for the insertion point */
      if (search_by_entry_key (dir->i_sb, &entry_key, &path, &de) != NAME_NOT_FOUND) {
            reiserfs_warning ("vs-7032: reiserfs_add_entry: "
                            "entry with this key (%k) already exists\n", &entry_key);

	    if (buffer != small_buf)
		reiserfs_kfree (buffer, buflen, dir->i_sb);
	    pathrelse (&path);
	    return -EBUSY;
	}
    }
  
    /* perform the insertion of the entry that we have prepared */
    retval = reiserfs_paste_into_item (th, &path, &entry_key, buffer, paste_size);
    if (buffer != small_buf)
	reiserfs_kfree (buffer, buflen, dir->i_sb);
    if (retval) {
	reiserfs_check_path(&path) ;
	return retval;
    }

    dir->i_size += paste_size;
    dir->i_blocks = ((dir->i_size + 511) >> 9);
    dir->i_mtime = dir->i_ctime = CURRENT_TIME;
    if (!S_ISDIR (inode->i_mode) && visible)
	// reiserfs_mkdir or reiserfs_rename will do that by itself
	reiserfs_update_sd (th, dir);

    reiserfs_check_path(&path) ;
    return 0;
}


//
// a portion of this function, particularly the VFS interface portion,
// was derived from minix or ext2's analog and evolved as the
// prototype did. You should be able to tell which portion by looking
// at the ext2 code and comparing. It's subfunctions contain no code
// used as a template unless they are so labeled.
//
static int reiserfs_create (struct inode * dir, struct dentry *dentry, int mode)
{
    int retval;
    struct inode * inode;
    int windex ;
    int jbegin_count = JOURNAL_PER_BALANCE_CNT * 2 ;
    struct reiserfs_transaction_handle th ;


    inode = new_inode(dir->i_sb) ;
    if (!inode) {
	return -ENOMEM ;
    }
    journal_begin(&th, dir->i_sb, jbegin_count) ;
    th.t_caller = "create" ;
    windex = push_journal_writer("reiserfs_create") ;
    inode = reiserfs_new_inode (&th, dir, mode, 0, 0/*i_size*/, dentry, inode, &retval);
    if (!inode) {
	pop_journal_writer(windex) ;
	journal_end(&th, dir->i_sb, jbegin_count) ;
	return retval;
    }
	
    inode->i_op = &reiserfs_file_inode_operations;
    inode->i_fop = &reiserfs_file_operations;
    inode->i_mapping->a_ops = &reiserfs_address_space_operations ;

    retval = reiserfs_add_entry (&th, dir, dentry->d_name.name, dentry->d_name.len, 
				inode, 1/*visible*/);
    if (retval) {
	inode->i_nlink--;
	reiserfs_update_sd (&th, inode);
	pop_journal_writer(windex) ;
	// FIXME: should we put iput here and have stat data deleted
	// in the same transactioin
	journal_end(&th, dir->i_sb, jbegin_count) ;
	iput (inode);
	return retval;
    }
    reiserfs_update_inode_transaction(inode) ;
    reiserfs_update_inode_transaction(dir) ;

    d_instantiate(dentry, inode);
    pop_journal_writer(windex) ;
    journal_end(&th, dir->i_sb, jbegin_count) ;
    return 0;
}


//
// a portion of this function, particularly the VFS interface portion,
// was derived from minix or ext2's analog and evolved as the
// prototype did. You should be able to tell which portion by looking
// at the ext2 code and comparing. It's subfunctions contain no code
// used as a template unless they are so labeled.
//
static int reiserfs_mknod (struct inode * dir, struct dentry *dentry, int mode, int rdev)
{
    int retval;
    struct inode * inode;
    int windex ;
    struct reiserfs_transaction_handle th ;
    int jbegin_count = JOURNAL_PER_BALANCE_CNT * 3; 

    inode = new_inode(dir->i_sb) ;
    if (!inode) {
	return -ENOMEM ;
    }
    journal_begin(&th, dir->i_sb, jbegin_count) ;
    windex = push_journal_writer("reiserfs_mknod") ;

    inode = reiserfs_new_inode (&th, dir, mode, 0, 0/*i_size*/, dentry, inode, &retval);
    if (!inode) {
	pop_journal_writer(windex) ;
	journal_end(&th, dir->i_sb, jbegin_count) ;
	return retval;
    }

    init_special_inode(inode, mode, rdev) ;

    //FIXME: needed for block and char devices only
    reiserfs_update_sd (&th, inode);

    reiserfs_update_inode_transaction(inode) ;
    reiserfs_update_inode_transaction(dir) ;

    retval = reiserfs_add_entry (&th, dir, dentry->d_name.name, dentry->d_name.len, 
				 inode, 1/*visible*/);
    if (retval) {
	inode->i_nlink--;
	reiserfs_update_sd (&th, inode);
	pop_journal_writer(windex) ;
	journal_end(&th, dir->i_sb, jbegin_count) ;
	iput (inode);
	return retval;
    }

    d_instantiate(dentry, inode);
    pop_journal_writer(windex) ;
    journal_end(&th, dir->i_sb, jbegin_count) ;
    return 0;
}


//
// a portion of this function, particularly the VFS interface portion,
// was derived from minix or ext2's analog and evolved as the
// prototype did. You should be able to tell which portion by looking
// at the ext2 code and comparing. It's subfunctions contain no code
// used as a template unless they are so labeled.
//
static int reiserfs_mkdir (struct inode * dir, struct dentry *dentry, int mode)
{
    int retval;
    struct inode * inode;
    int windex ;
    struct reiserfs_transaction_handle th ;
    int jbegin_count = JOURNAL_PER_BALANCE_CNT * 3; 

    inode = new_inode(dir->i_sb) ;
    if (!inode) {
	return -ENOMEM ;
    }
    journal_begin(&th, dir->i_sb, jbegin_count) ;
    windex = push_journal_writer("reiserfs_mkdir") ;

    /* inc the link count now, so another writer doesn't overflow it while
    ** we sleep later on.
    */
    INC_DIR_INODE_NLINK(dir)

    mode = S_IFDIR | mode;
    inode = reiserfs_new_inode (&th, dir, mode, 0/*symlink*/,
				old_format_only (dir->i_sb) ? EMPTY_DIR_SIZE_V1 : EMPTY_DIR_SIZE,
				dentry, inode, &retval);
    if (!inode) {
	pop_journal_writer(windex) ;
	dir->i_nlink-- ;
	journal_end(&th, dir->i_sb, jbegin_count) ;
	return retval;
    }
    reiserfs_update_inode_transaction(inode) ;
    reiserfs_update_inode_transaction(dir) ;

    inode->i_op = &reiserfs_dir_inode_operations;
    inode->i_fop = &reiserfs_dir_operations;

    // note, _this_ add_entry will not update dir's stat data
    retval = reiserfs_add_entry (&th, dir, dentry->d_name.name, dentry->d_name.len, 
				inode, 1/*visible*/);
    if (retval) {
	inode->i_nlink = 0;
	DEC_DIR_INODE_NLINK(dir);
	reiserfs_update_sd (&th, inode);
	pop_journal_writer(windex) ;
	journal_end(&th, dir->i_sb, jbegin_count) ;
	iput (inode);
	return retval;
    }

    // the above add_entry did not update dir's stat data
    reiserfs_update_sd (&th, dir);

    d_instantiate(dentry, inode);
    pop_journal_writer(windex) ;
    journal_end(&th, dir->i_sb, jbegin_count) ;
    return 0;
}

static inline int reiserfs_empty_dir(struct inode *inode) {
    /* we can cheat because an old format dir cannot have
    ** EMPTY_DIR_SIZE, and a new format dir cannot have
    ** EMPTY_DIR_SIZE_V1.  So, if the inode is either size, 
    ** regardless of disk format version, the directory is empty.
    */
    if (inode->i_size != EMPTY_DIR_SIZE &&
        inode->i_size != EMPTY_DIR_SIZE_V1) {
        return 0 ;
    }
    return 1 ;
}


//
// a portion of this function, particularly the VFS interface portion,
// was derived from minix or ext2's analog and evolved as the
// prototype did. You should be able to tell which portion by looking
// at the ext2 code and comparing. It's subfunctions contain no code
// used as a template unless they are so labeled.
//
static int reiserfs_rmdir (struct inode * dir, struct dentry *dentry)
{
    int retval;
    struct inode * inode;
    int windex ;
    struct reiserfs_transaction_handle th ;
    int jbegin_count; 
    INITIALIZE_PATH (path);
    struct reiserfs_dir_entry de;


    /* we will be doing 2 balancings and update 2 stat data */
    jbegin_count = JOURNAL_PER_BALANCE_CNT * 2 + 2;

    journal_begin(&th, dir->i_sb, jbegin_count) ;
    windex = push_journal_writer("reiserfs_rmdir") ;

    de.de_gen_number_bit_string = 0;
    if (reiserfs_find_entry (dir, dentry->d_name.name, dentry->d_name.len, &path, &de) == NAME_NOT_FOUND) {
	retval = -ENOENT;
	goto end_rmdir;
    }
    inode = dentry->d_inode;

    reiserfs_update_inode_transaction(inode) ;
    reiserfs_update_inode_transaction(dir) ;

    if (de.de_objectid != inode->i_ino) {
	// FIXME: compare key of an object and a key found in the
	// entry
	retval = -EIO;
	goto end_rmdir;
    }
    if (!reiserfs_empty_dir(inode)) {
	retval = -ENOTEMPTY;
	goto end_rmdir;
    }

    /* cut entry from dir directory */
    retval = reiserfs_cut_from_item (&th, &path, &(de.de_entry_key), dir, 
                                     NULL, /* page */ 
				     0/*new file size - not used here*/);
    if (retval < 0)
	goto end_rmdir;

    if ( inode->i_nlink != 2 && inode->i_nlink != 1 )
	printk ("reiserfs_rmdir: empty directory has nlink != 2 (%d)\n", inode->i_nlink);

    inode->i_nlink = 0;
    inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
    reiserfs_update_sd (&th, inode);

    DEC_DIR_INODE_NLINK(dir)
    dir->i_size -= (DEH_SIZE + de.de_entrylen);
    dir->i_blocks = ((dir->i_size + 511) >> 9);
    reiserfs_update_sd (&th, dir);

    /* prevent empty directory from getting lost */
    add_save_link (&th, inode, 0/* not truncate */);

    pop_journal_writer(windex) ;
    journal_end(&th, dir->i_sb, jbegin_count) ;
    reiserfs_check_path(&path) ;
    return 0;
	
 end_rmdir:
    /* we must release path, because we did not call
       reiserfs_cut_from_item, or reiserfs_cut_from_item does not
       release path if operation was not complete */
    pathrelse (&path);
    pop_journal_writer(windex) ;
    journal_end(&th, dir->i_sb, jbegin_count) ;
    return retval;	
}


//
// a portion of this function, particularly the VFS interface portion,
// was derived from minix or ext2's analog and evolved as the
// prototype did. You should be able to tell which portion by looking
// at the ext2 code and comparing. It's subfunctions contain no code
// used as a template unless they are so labeled.
//
static int reiserfs_unlink (struct inode * dir, struct dentry *dentry)
{
    int retval;
    struct inode * inode;
    struct reiserfs_dir_entry de;
    INITIALIZE_PATH (path);
    int windex ;
    struct reiserfs_transaction_handle th ;
    int jbegin_count;

    inode = dentry->d_inode;

    /* in this transaction we can be doing at max two balancings and update
       two stat datas */
    jbegin_count = JOURNAL_PER_BALANCE_CNT * 2 + 2;

    journal_begin(&th, dir->i_sb, jbegin_count) ;
    windex = push_journal_writer("reiserfs_unlink") ;
	
    de.de_gen_number_bit_string = 0;
    if (reiserfs_find_entry (dir, dentry->d_name.name, dentry->d_name.len, &path, &de) == NAME_NOT_FOUND) {
	retval = -ENOENT;
	goto end_unlink;
    }

    reiserfs_update_inode_transaction(inode) ;
    reiserfs_update_inode_transaction(dir) ;

    if (de.de_objectid != inode->i_ino) {
	// FIXME: compare key of an object and a key found in the
	// entry
	retval = -EIO;
	goto end_unlink;
    }
  
    if (!inode->i_nlink) {
	printk("reiserfs_unlink: deleting nonexistent file (%s:%lu), %d\n",
	       kdevname(inode->i_dev), inode->i_ino, inode->i_nlink);
	inode->i_nlink = 1;
    }

    retval = reiserfs_cut_from_item (&th, &path, &(de.de_entry_key), dir, NULL, 0);
    if (retval < 0)
	goto end_unlink;

    inode->i_nlink--;
    inode->i_ctime = CURRENT_TIME;
    reiserfs_update_sd (&th, inode);

    dir->i_size -= (de.de_entrylen + DEH_SIZE);
    dir->i_blocks = ((dir->i_size + 511) >> 9);
    dir->i_ctime = dir->i_mtime = CURRENT_TIME;
    reiserfs_update_sd (&th, dir);

    if (!inode->i_nlink)
       /* prevent file from getting lost */
       add_save_link (&th, inode, 0/* not truncate */);

    pop_journal_writer(windex) ;
    journal_end(&th, dir->i_sb, jbegin_count) ;
    reiserfs_check_path(&path) ;
    return 0;

 end_unlink:
    pathrelse (&path);
    pop_journal_writer(windex) ;
    journal_end(&th, dir->i_sb, jbegin_count) ;
    reiserfs_check_path(&path) ;
    return retval;
}