[linux-2.6-block.git] / fs / btrfs / bit-radix.c

/*
 * Copyright (C) 2007 Oracle.  All rights reserved.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public
 * License v2 as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public
 * License along with this program; if not, write to the
 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
 * Boston, MA 021110-1307, USA.
 */

#include "bit-radix.h"

#define BIT_ARRAY_BYTES 256
#define BIT_RADIX_BITS_PER_ARRAY ((BIT_ARRAY_BYTES - sizeof(unsigned long)) * 8)

extern struct kmem_cache *btrfs_bit_radix_cachep;
int set_radix_bit(struct radix_tree_root *radix, unsigned long bit)
{
	unsigned long *bits;
	unsigned long slot;
	int bit_slot;
	int ret;

	slot = bit / BIT_RADIX_BITS_PER_ARRAY;
	bit_slot = bit % BIT_RADIX_BITS_PER_ARRAY;

	bits = radix_tree_lookup(radix, slot);
	if (!bits) {
		bits = kmem_cache_alloc(btrfs_bit_radix_cachep, GFP_NOFS);
		if (!bits)
			return -ENOMEM;
		memset(bits + 1, 0, BIT_ARRAY_BYTES - sizeof(unsigned long));
		bits[0] = slot;
		ret = radix_tree_insert(radix, slot, bits);
		if (ret)
			return ret;
	}
	ret = test_and_set_bit(bit_slot, bits + 1);
	if (ret < 0)
		ret = 1;
	return ret;
}

int test_radix_bit(struct radix_tree_root *radix, unsigned long bit)
{
	unsigned long *bits;
	unsigned long slot;
	int bit_slot;

	slot = bit / BIT_RADIX_BITS_PER_ARRAY;
	bit_slot = bit % BIT_RADIX_BITS_PER_ARRAY;

	bits = radix_tree_lookup(radix, slot);
	if (!bits)
		return 0;
	return test_bit(bit_slot, bits + 1);
}

int clear_radix_bit(struct radix_tree_root *radix, unsigned long bit)
{
	unsigned long *bits;
	unsigned long slot;
	int bit_slot;
	int i;
	int empty = 1;

	slot = bit / BIT_RADIX_BITS_PER_ARRAY;
	bit_slot = bit % BIT_RADIX_BITS_PER_ARRAY;

	bits = radix_tree_lookup(radix, slot);
	if (!bits)
		return 0;
	clear_bit(bit_slot, bits + 1);
	for (i = 1; i < BIT_ARRAY_BYTES / sizeof(unsigned long); i++) {
		if (bits[i]) {
			empty = 0;
			break;
		}
	}
	if (empty) {
		bits = radix_tree_delete(radix, slot);
		BUG_ON(!bits);
		kmem_cache_free(btrfs_bit_radix_cachep, bits);
	}
	return 0;
}

int find_first_radix_bit(struct radix_tree_root *radix, unsigned long *retbits,
			 unsigned long start, int nr)
{
	unsigned long *bits;
	unsigned long *gang[4];
	int found;
	int ret;
	int i;
	int total_found = 0;
	unsigned long slot;

	slot = start / BIT_RADIX_BITS_PER_ARRAY;
	ret = radix_tree_gang_lookup(radix, (void **)gang, slot,
				     ARRAY_SIZE(gang));
	found = start % BIT_RADIX_BITS_PER_ARRAY;
	for (i = 0; i < ret && nr > 0; i++) {
		bits = gang[i];
		while(nr > 0) {
			found = find_next_bit(bits + 1,
					      BIT_RADIX_BITS_PER_ARRAY,
					      found);
			if (found < BIT_RADIX_BITS_PER_ARRAY) {
				*retbits = bits[0] *
					BIT_RADIX_BITS_PER_ARRAY + found;
				retbits++;
				nr--;
				total_found++;
				found++;
			} else
				break;
		}
		found = 0;
	}
	return total_found;
}
Commit	Line	Data
6cbd5570 CM	1	/*
	2	* Copyright (C) 2007 Oracle. All rights reserved.
	3	*
	4	* This program is free software; you can redistribute it and/or
	5	* modify it under the terms of the GNU General Public
	6	* License v2 as published by the Free Software Foundation.
	7	*
	8	* This program is distributed in the hope that it will be useful,
	9	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	10	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
	11	* General Public License for more details.
	12	*
	13	* You should have received a copy of the GNU General Public
	14	* License along with this program; if not, write to the
	15	* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
	16	* Boston, MA 021110-1307, USA.
	17	*/
	18
8ef97622 CM	19	#include "bit-radix.h"
	20
	21	#define BIT_ARRAY_BYTES 256
	22	#define BIT_RADIX_BITS_PER_ARRAY ((BIT_ARRAY_BYTES - sizeof(unsigned long)) * 8)
	23
2c90e5d6	24	extern struct kmem_cache *btrfs_bit_radix_cachep;
8ef97622 CM	25	int set_radix_bit(struct radix_tree_root *radix, unsigned long bit)
	26	{
	27	unsigned long *bits;
	28	unsigned long slot;
	29	int bit_slot;
	30	int ret;
	31
	32	slot = bit / BIT_RADIX_BITS_PER_ARRAY;
	33	bit_slot = bit % BIT_RADIX_BITS_PER_ARRAY;
	34
	35	bits = radix_tree_lookup(radix, slot);
	36	if (!bits) {
2c90e5d6	37	bits = kmem_cache_alloc(btrfs_bit_radix_cachep, GFP_NOFS);
8ef97622 CM	38	if (!bits)
	39	return -ENOMEM;
	40	memset(bits + 1, 0, BIT_ARRAY_BYTES - sizeof(unsigned long));
	41	bits[0] = slot;
	42	ret = radix_tree_insert(radix, slot, bits);
	43	if (ret)
	44	return ret;
	45	}
be744175 CM	46	ret = test_and_set_bit(bit_slot, bits + 1);
	47	if (ret < 0)
	48	ret = 1;
	49	return ret;
8ef97622 CM	50	}
	51
	52	int test_radix_bit(struct radix_tree_root *radix, unsigned long bit)
	53	{
	54	unsigned long *bits;
	55	unsigned long slot;
	56	int bit_slot;
	57
	58	slot = bit / BIT_RADIX_BITS_PER_ARRAY;
	59	bit_slot = bit % BIT_RADIX_BITS_PER_ARRAY;
	60
	61	bits = radix_tree_lookup(radix, slot);
	62	if (!bits)
	63	return 0;
	64	return test_bit(bit_slot, bits + 1);
	65	}
	66
	67	int clear_radix_bit(struct radix_tree_root *radix, unsigned long bit)
	68	{
	69	unsigned long *bits;
	70	unsigned long slot;
	71	int bit_slot;
	72	int i;
	73	int empty = 1;
	74
	75	slot = bit / BIT_RADIX_BITS_PER_ARRAY;
	76	bit_slot = bit % BIT_RADIX_BITS_PER_ARRAY;
	77
	78	bits = radix_tree_lookup(radix, slot);
	79	if (!bits)
	80	return 0;
	81	clear_bit(bit_slot, bits + 1);
8ef97622 CM	82	for (i = 1; i < BIT_ARRAY_BYTES / sizeof(unsigned long); i++) {
	83	if (bits[i]) {
	84	empty = 0;
	85	break;
	86	}
	87	}
8ef97622 CM	88	if (empty) {
	89	bits = radix_tree_delete(radix, slot);
	90	BUG_ON(!bits);
2c90e5d6	91	kmem_cache_free(btrfs_bit_radix_cachep, bits);
8ef97622 CM	92	}
	93	return 0;
	94	}
	95
	96	int find_first_radix_bit(struct radix_tree_root radix, unsigned long retbits,
e37c9e69	97	unsigned long start, int nr)
8ef97622 CM	98	{
	99	unsigned long *bits;
	100	unsigned long *gang[4];
	101	int found;
	102	int ret;
	103	int i;
	104	int total_found = 0;
e37c9e69	105	unsigned long slot;
8ef97622	106
e37c9e69 CM	107	slot = start / BIT_RADIX_BITS_PER_ARRAY;
	108	ret = radix_tree_gang_lookup(radix, (void **)gang, slot,
	109	ARRAY_SIZE(gang));
	110	found = start % BIT_RADIX_BITS_PER_ARRAY;
8ef97622	111	for (i = 0; i < ret && nr > 0; i++) {
8ef97622 CM	112	bits = gang[i];
	113	while(nr > 0) {
	114	found = find_next_bit(bits + 1,
	115	BIT_RADIX_BITS_PER_ARRAY,
	116	found);
	117	if (found < BIT_RADIX_BITS_PER_ARRAY) {
	118	retbits = bits[0]
	119	BIT_RADIX_BITS_PER_ARRAY + found;
	120	retbits++;
	121	nr--;
	122	total_found++;
	123	found++;
	124	} else
	125	break;
	126	}
e37c9e69	127	found = 0;
8ef97622 CM	128	}
	129	return total_found;
	130	}