ibalance.c

reiserfsprogs-3.6.19.tar.gz 源码 给有需要的人！

 */
static void internal_move_pointers_items (reiserfs_filsys_t * fs,
					  struct buffer_info * dest_bi, 
					  struct buffer_info * src_bi, 
					  int last_first, int cpy_num, int del_par)
{
    int first_pointer;
    int first_item;
    
    internal_copy_pointers_items (fs, dest_bi, src_bi->bi_bh, last_first, cpy_num);
    
    if (last_first == FIRST_TO_LAST) {	/* shift_left occurs */
	first_pointer = 0;
	first_item = 0;
	/* delete cpy_num - del_par pointers and keys starting for pointers with first_pointer, 
	   for key - with first_item */
	internal_delete_pointers_items (fs, src_bi, first_pointer, first_item, cpy_num - del_par);
    } else {			/* shift_right occurs */
	int i, j;
	
	i = ( cpy_num - del_par == ( j = B_NR_ITEMS(src_bi->bi_bh)) + 1 ) ? 0 : j - cpy_num + del_par;
	
	internal_delete_pointers_items (fs, src_bi, j + 1 - cpy_num + del_par, i, cpy_num - del_par);
    }
}

/* Insert n_src'th key of buffer src before n_dest'th key of buffer dest. */
static void internal_insert_key (reiserfs_filsys_t * fs,
				 struct buffer_info * dest_bi, 
				 int dest_position_before,                 /* insert key before key with n_dest number */
				 struct buffer_head * src, 
				 int src_position )
{
    struct buffer_head * dest = dest_bi->bi_bh;
    int nr;
    struct block_head * blkh;
    struct key * key;

    blkh = B_BLK_HEAD(dest);
    nr = get_blkh_nr_items (blkh);

    /* prepare space for inserting key */
    key = B_N_PDELIM_KEY (dest, dest_position_before);
    memmove (key + 1, key, (nr - dest_position_before) * KEY_SIZE + (nr + 1) * DC_SIZE);

    /* insert key */
    memcpy (key, B_N_PDELIM_KEY(src, src_position), KEY_SIZE);

    /* Change dirt, free space, item number fields. */
    set_blkh_nr_items (blkh, get_blkh_nr_items (blkh) + 1);
    set_blkh_free_space (blkh, get_blkh_free_space (blkh) - KEY_SIZE);

    mark_buffer_dirty (dest);

    if (dest_bi->bi_parent) {
	struct disk_child * dc;
	
	dc = B_N_CHILD(dest_bi->bi_parent,dest_bi->bi_position);
	set_dc_child_size (dc, get_dc_child_size (dc) + KEY_SIZE);
	mark_buffer_dirty (dest_bi->bi_parent);
    }
}



/* Insert d_key'th (delimiting) key from buffer cfl to tail of dest. 
 * Copy pointer_amount node pointers and pointer_amount - 1 items from buffer src to buffer dest.
 * Replace  d_key'th key in buffer cfl.
 * Delete pointer_amount items and node pointers from buffer src.
 */
/* this can be invoked both to shift from S to L and from R to S */
static void internal_shift_left (int mode,	/* INTERNAL_FROM_S_TO_L | INTERNAL_FROM_R_TO_S */
				 struct tree_balance * tb, int h,
				 int pointer_amount)
{
    struct buffer_info dest_bi, src_bi;
    struct buffer_head * cf;
    int d_key_position;

    internal_define_dest_src_infos (mode, tb, h, &dest_bi, &src_bi, &d_key_position, &cf);

    /*printk("pointer_amount = %d\n",pointer_amount);*/

    if (pointer_amount) {
	/* insert delimiting key from common father of dest and src to node dest into position B_NR_ITEM(dest) */
	internal_insert_key (tb->tb_fs, &dest_bi, B_NR_ITEMS(dest_bi.bi_bh), cf, d_key_position);

	if (B_NR_ITEMS(src_bi.bi_bh) == pointer_amount - 1) {
	    if (src_bi.bi_position/*src->b_item_order*/ == 0)
		replace_key (tb->tb_fs, cf, d_key_position, src_bi.bi_parent/*src->b_parent*/, 0);
	} else
	    replace_key (tb->tb_fs, cf, d_key_position, src_bi.bi_bh, pointer_amount - 1);
    }
    /* last parameter is del_parameter */
    internal_move_pointers_items (tb->tb_fs, &dest_bi, &src_bi, FIRST_TO_LAST, pointer_amount, 0);

}

/* Insert delimiting key to L[h].
 * Copy n node pointers and n - 1 items from buffer S[h] to L[h].
 * Delete n - 1 items and node pointers from buffer S[h].
 */
/* it always shifts from S[h] to L[h] */
static void internal_shift1_left (struct tree_balance * tb, 
				  int h, int pointer_amount)
{
    struct buffer_info dest_bi, src_bi;
    struct buffer_head * cf;
    int d_key_position;
    
    internal_define_dest_src_infos (INTERNAL_SHIFT_FROM_S_TO_L, tb, h, &dest_bi, &src_bi, &d_key_position, &cf);
    
    if ( pointer_amount > 0 ) /* insert lkey[h]-th key  from CFL[h] to left neighbor L[h] */
	internal_insert_key (tb->tb_fs, &dest_bi, B_NR_ITEMS(dest_bi.bi_bh), cf, d_key_position);
    
    /* last parameter is del_parameter */
    internal_move_pointers_items (tb->tb_fs, &dest_bi, &src_bi, FIRST_TO_LAST, pointer_amount, 1);
}


/* Insert d_key'th (delimiting) key from buffer cfr to head of dest. 
 * Copy n node pointers and n - 1 items from buffer src to buffer dest.
 * Replace  d_key'th key in buffer cfr.
 * Delete n items and node pointers from buffer src.
 */
static void internal_shift_right (int mode,	/* INTERNAL_FROM_S_TO_R | INTERNAL_FROM_L_TO_S */
				  struct tree_balance * tb, int h,
				  int pointer_amount)
{
    struct buffer_info dest_bi, src_bi;
    struct buffer_head * cf;
    int d_key_position;
    int nr;


    internal_define_dest_src_infos (mode, tb, h, &dest_bi, &src_bi, &d_key_position, &cf);

    nr = B_NR_ITEMS (src_bi.bi_bh);

    if (pointer_amount > 0) {
	/* insert delimiting key from common father of dest and src to dest node into position 0 */
	internal_insert_key (tb->tb_fs, &dest_bi, 0, cf, d_key_position);
	if (nr == pointer_amount - 1) {
	    /* when S[h] disappers replace left delemiting key as well */
	    if (tb->CFL[h])
		replace_key(tb->tb_fs, cf, d_key_position, tb->CFL[h], tb->lkey[h]);
	} else
	    replace_key(tb->tb_fs, cf, d_key_position, src_bi.bi_bh, nr - pointer_amount);
    }      

    /* last parameter is del_parameter */
    internal_move_pointers_items (tb->tb_fs, &dest_bi, &src_bi, LAST_TO_FIRST, pointer_amount, 0);
}

/* Insert delimiting key to R[h].
 * Copy n node pointers and n - 1 items from buffer S[h] to R[h].
 * Delete n - 1 items and node pointers from buffer S[h].
 */
/* it always shift from S[h] to R[h] */
static void internal_shift1_right (struct tree_balance * tb, 
				   int h, int pointer_amount)
{
    struct buffer_info dest_bi, src_bi;
    struct buffer_head * cf;
    int d_key_position;

    internal_define_dest_src_infos (INTERNAL_SHIFT_FROM_S_TO_R, tb, h, &dest_bi, &src_bi, &d_key_position, &cf);
    
    if (pointer_amount > 0) /* insert rkey from CFR[h] to right neighbor R[h] */
	internal_insert_key (tb->tb_fs, &dest_bi, 0, cf, d_key_position);
    
    /* last parameter is del_parameter */
    internal_move_pointers_items (tb->tb_fs, &dest_bi, &src_bi, LAST_TO_FIRST, pointer_amount, 1);
}


/* Delete insert_num node pointers together with their left items
 * and balance current node.*/
static void balance_internal_when_delete (struct tree_balance * tb, 
					  int h, int child_pos)
{
    int insert_num;
    int n;
    struct buffer_head * tbSh = PATH_H_PBUFFER (tb->tb_path, h);
    struct buffer_info bi;

    insert_num = tb->insert_size[h] / ((int)(DC_SIZE + KEY_SIZE));
  
    /* delete child-node-pointer(s) together with their left item(s) */
    bi.bi_bh = tbSh;

    bi.bi_parent = PATH_H_PPARENT (tb->tb_path, h);

    bi.bi_position = PATH_H_POSITION (tb->tb_path, h + 1);

    internal_delete_childs (tb->tb_fs, &bi, child_pos, -insert_num);

    n = B_NR_ITEMS(tbSh);

    if ( tb->lnum[h] == 0 && tb->rnum[h] == 0 ) {
	if ( tb->blknum[h] == 0 ) {
	    /* node S[h] (root of the tree) is empty now */
	    struct buffer_head *new_root;
	    struct reiserfs_super_block * sb;

	    /* choose a new root */
	    if ( ! tb->L[h-1] || ! B_NR_ITEMS(tb->L[h-1]) )
		new_root = tb->R[h-1];
	    else
		new_root = tb->L[h-1];

	    /* update super block's tree height and pointer to a root block */
	    sb = tb->tb_fs->fs_ondisk_sb;
	    set_sb_root_block (sb, new_root->b_blocknr);
	    set_sb_tree_height (sb, get_sb_tree_height (sb) - 1);

	    mark_buffer_dirty (tb->tb_fs->fs_super_bh);
	    tb->tb_fs->fs_dirt = 1;

	    /* mark buffer S[h] not uptodate and put it in free list */
	    reiserfs_invalidate_buffer(tb, tbSh, 1);
	    return;
	}
	return;
    }

    if ( tb->L[h] && tb->lnum[h] == -B_NR_ITEMS(tb->L[h]) - 1 ) { /* join S[h] with L[h] */
	internal_shift_left (INTERNAL_SHIFT_FROM_S_TO_L, tb, h, n + 1);/*tb->L[h], tb->CFL[h], tb->lkey[h], tb->S[h], n+1);*/
	reiserfs_invalidate_buffer(tb, tbSh, 1); /* preserve not needed, internal, 1 mean free block */

	return;
    }

    if ( tb->R[h] &&  tb->rnum[h] == -B_NR_ITEMS(tb->R[h]) - 1 ) { /* join S[h] with R[h] */
	internal_shift_right (INTERNAL_SHIFT_FROM_S_TO_R, tb, h, n + 1);
	reiserfs_invalidate_buffer (tb, tbSh, 1);
	return;
    }

    if ( tb->lnum[h] < 0 ) { /* borrow from left neighbor L[h] */
	internal_shift_right (INTERNAL_SHIFT_FROM_L_TO_S, tb, h, -tb->lnum[h]);
	return;
    }

    if ( tb->rnum[h] < 0 ) { /* borrow from right neighbor R[h] */
	internal_shift_left (INTERNAL_SHIFT_FROM_R_TO_S, tb, h, -tb->rnum[h]);/*tb->S[h], tb->CFR[h], tb->rkey[h], tb->R[h], -tb->rnum[h]);*/
	return;
    }

    if ( tb->lnum[h] > 0 ) { /* split S[h] into two parts and put them into neighbors */
	internal_shift_left (INTERNAL_SHIFT_FROM_S_TO_L, tb, h, tb->lnum[h]);/*tb->L[h], tb->CFL[h], tb->lkey[h], tb->S[h], tb->lnum[h]);*/
	internal_shift_right (INTERNAL_SHIFT_FROM_S_TO_R, tb, h, tb->rnum[h]);
	reiserfs_invalidate_buffer (tb, tbSh, 1);

	return;
    }
    reiserfs_panic ("balance_internal_when_delete", "unexpected tb->lnum[%d]==%d or tb->rnum[%d]==%d",
		    h, tb->lnum[h], h, tb->rnum[h]);
}


/* Replace delimiting key of buffers L[h] and S[h] by the given key.*/
void replace_lkey (struct tree_balance * tb,
		   int h, struct item_head * key)
{
    if (B_NR_ITEMS(PATH_H_PBUFFER(tb->tb_path, h)) == 0)
	return;

    memcpy (B_N_PDELIM_KEY(tb->CFL[h],tb->lkey[h]), key, KEY_SIZE);

    mark_buffer_dirty (tb->CFL[h]);
}


/* Replace delimiting key of buffers S[h] and R[h] by the given key.*/
void replace_rkey (struct tree_balance * tb,
		   int h, struct item_head * key)
{
    memcpy (B_N_PDELIM_KEY(tb->CFR[h],tb->rkey[h]), key, KEY_SIZE);
    
    mark_buffer_dirty (tb->CFR[h]);
}



int balance_internal (struct tree_balance * tb,			/* tree_balance structure 		*/
		      int h,					/* level of the tree 			*/
		      int child_pos,
		      struct item_head * insert_key,		/* key for insertion on higher level   	*/
		      struct buffer_head ** insert_ptr)	/* node for insertion on higher level*/
  /* if inserting/pasting
   {
   child_pos is the position of the node-pointer in S[h] that	 *
   pointed to S[h-1] before balancing of the h-1 level;		 *
   this means that new pointers and items must be inserted AFTER *
   child_pos
   }