[deliverable/linux.git] / fs / hfsplus / bitmap.c

/*
 *  linux/fs/hfsplus/bitmap.c
 *
 * Copyright (C) 2001
 * Brad Boyer (flar@allandria.com)
 * (C) 2003 Ardis Technologies <roman@ardistech.com>
 *
 * Handling of allocation file
 */

#include <linux/pagemap.h>

#include "hfsplus_fs.h"
#include "hfsplus_raw.h"

#define PAGE_CACHE_BITS	(PAGE_CACHE_SIZE * 8)

int hfsplus_block_allocate(struct super_block *sb, u32 size,
		u32 offset, u32 *max)
{
	struct hfsplus_sb_info *sbi = HFSPLUS_SB(sb);
	struct page *page;
	struct address_space *mapping;
	__be32 *pptr, *curr, *end;
	u32 mask, start, len, n;
	__be32 val;
	int i;

	len = *max;
	if (!len)
		return size;

	dprint(DBG_BITMAP, "block_allocate: %u,%u,%u\n", size, offset, len);
	mutex_lock(&sbi->alloc_mutex);
	mapping = sbi->alloc_file->i_mapping;
	page = read_mapping_page(mapping, offset / PAGE_CACHE_BITS, NULL);
	if (IS_ERR(page)) {
		start = size;
		goto out;
	}
	pptr = kmap(page);
	curr = pptr + (offset & (PAGE_CACHE_BITS - 1)) / 32;
	i = offset % 32;
	offset &= ~(PAGE_CACHE_BITS - 1);
	if ((size ^ offset) / PAGE_CACHE_BITS)
		end = pptr + PAGE_CACHE_BITS / 32;
	else
		end = pptr + ((size + 31) & (PAGE_CACHE_BITS - 1)) / 32;

	/* scan the first partial u32 for zero bits */
	val = *curr;
	if (~val) {
		n = be32_to_cpu(val);
		mask = (1U << 31) >> i;
		for (; i < 32; mask >>= 1, i++) {
			if (!(n & mask))
				goto found;
		}
	}
	curr++;

	/* scan complete u32s for the first zero bit */
	while (1) {
		while (curr < end) {
			val = *curr;
			if (~val) {
				n = be32_to_cpu(val);
				mask = 1 << 31;
				for (i = 0; i < 32; mask >>= 1, i++) {
					if (!(n & mask))
						goto found;
				}
			}
			curr++;
		}
		kunmap(page);
		offset += PAGE_CACHE_BITS;
		if (offset >= size)
			break;
		page = read_mapping_page(mapping, offset / PAGE_CACHE_BITS,
					 NULL);
		if (IS_ERR(page)) {
			start = size;
			goto out;
		}
		curr = pptr = kmap(page);
		if ((size ^ offset) / PAGE_CACHE_BITS)
			end = pptr + PAGE_CACHE_BITS / 32;
		else
			end = pptr + ((size + 31) & (PAGE_CACHE_BITS - 1)) / 32;
	}
	dprint(DBG_BITMAP, "bitmap full\n");
	start = size;
	goto out;

found:
	start = offset + (curr - pptr) * 32 + i;
	if (start >= size) {
		dprint(DBG_BITMAP, "bitmap full\n");
		goto out;
	}
	/* do any partial u32 at the start */
	len = min(size - start, len);
	while (1) {
		n |= mask;
		if (++i >= 32)
			break;
		mask >>= 1;
		if (!--len || n & mask)
			goto done;
	}
	if (!--len)
		goto done;
	*curr++ = cpu_to_be32(n);
	/* do full u32s */
	while (1) {
		while (curr < end) {
			n = be32_to_cpu(*curr);
			if (len < 32)
				goto last;
			if (n) {
				len = 32;
				goto last;
			}
			*curr++ = cpu_to_be32(0xffffffff);
			len -= 32;
		}
		set_page_dirty(page);
		kunmap(page);
		offset += PAGE_CACHE_BITS;
		page = read_mapping_page(mapping, offset / PAGE_CACHE_BITS,
					 NULL);
		if (IS_ERR(page)) {
			start = size;
			goto out;
		}
		pptr = kmap(page);
		curr = pptr;
		end = pptr + PAGE_CACHE_BITS / 32;
	}
last:
	/* do any partial u32 at end */
	mask = 1U << 31;
	for (i = 0; i < len; i++) {
		if (n & mask)
			break;
		n |= mask;
		mask >>= 1;
	}
done:
	*curr = cpu_to_be32(n);
	set_page_dirty(page);
	kunmap(page);
	*max = offset + (curr - pptr) * 32 + i - start;
	sbi->free_blocks -= *max;
	sb->s_dirt = 1;
	dprint(DBG_BITMAP, "-> %u,%u\n", start, *max);
out:
	mutex_unlock(&sbi->alloc_mutex);
	return start;
}

int hfsplus_block_free(struct super_block *sb, u32 offset, u32 count)
{
	struct hfsplus_sb_info *sbi = HFSPLUS_SB(sb);
	struct page *page;
	struct address_space *mapping;
	__be32 *pptr, *curr, *end;
	u32 mask, len, pnr;
	int i;

	/* is there any actual work to be done? */
	if (!count)
		return 0;

	dprint(DBG_BITMAP, "block_free: %u,%u\n", offset, count);
	/* are all of the bits in range? */
	if ((offset + count) > sbi->total_blocks)
		return -2;

	mutex_lock(&sbi->alloc_mutex);
	mapping = sbi->alloc_file->i_mapping;
	pnr = offset / PAGE_CACHE_BITS;
	page = read_mapping_page(mapping, pnr, NULL);
	pptr = kmap(page);
	curr = pptr + (offset & (PAGE_CACHE_BITS - 1)) / 32;
	end = pptr + PAGE_CACHE_BITS / 32;
	len = count;

	/* do any partial u32 at the start */
	i = offset % 32;
	if (i) {
		int j = 32 - i;
		mask = 0xffffffffU << j;
		if (j > count) {
			mask |= 0xffffffffU >> (i + count);
			*curr++ &= cpu_to_be32(mask);
			goto out;
		}
		*curr++ &= cpu_to_be32(mask);
		count -= j;
	}

	/* do full u32s */
	while (1) {
		while (curr < end) {
			if (count < 32)
				goto done;
			*curr++ = 0;
			count -= 32;
		}
		if (!count)
			break;
		set_page_dirty(page);
		kunmap(page);
		page = read_mapping_page(mapping, ++pnr, NULL);
		pptr = kmap(page);
		curr = pptr;
		end = pptr + PAGE_CACHE_BITS / 32;
	}
done:
	/* do any partial u32 at end */
	if (count) {
		mask = 0xffffffffU >> count;
		*curr &= cpu_to_be32(mask);
	}
out:
	set_page_dirty(page);
	kunmap(page);
	sbi->free_blocks += len;
	sb->s_dirt = 1;
	mutex_unlock(&sbi->alloc_mutex);

	return 0;
}
Commit	Line	Data
1da177e4 LT	1	/*
	2	* linux/fs/hfsplus/bitmap.c
	3	*
	4	* Copyright (C) 2001
	5	* Brad Boyer (flar@allandria.com)
	6	* (C) 2003 Ardis Technologies <roman@ardistech.com>
	7	*
	8	* Handling of allocation file
	9	*/
	10
	11	#include <linux/pagemap.h>
	12
	13	#include "hfsplus_fs.h"
	14	#include "hfsplus_raw.h"
	15
	16	#define PAGE_CACHE_BITS (PAGE_CACHE_SIZE * 8)
	17
2753cc28 AS	18	int hfsplus_block_allocate(struct super_block *sb, u32 size,
2753cc28 AS	19	u32 offset, u32 *max)
1da177e4	20	{
dd73a01a	21	struct hfsplus_sb_info *sbi = HFSPLUS_SB(sb);
1da177e4 LT	22	struct page *page;
	23	struct address_space *mapping;
	24	__be32 pptr, curr, *end;
	25	u32 mask, start, len, n;
	26	__be32 val;
	27	int i;
	28
	29	len = *max;
	30	if (!len)
	31	return size;
	32
	33	dprint(DBG_BITMAP, "block_allocate: %u,%u,%u\n", size, offset, len);
dd73a01a CH	34	mutex_lock(&sbi->alloc_mutex);
dd73a01a CH	35	mapping = sbi->alloc_file->i_mapping;
090d2b18	36	page = read_mapping_page(mapping, offset / PAGE_CACHE_BITS, NULL);
649f1ee6 ES	37	if (IS_ERR(page)) {
	38	start = size;
	39	goto out;
	40	}
1da177e4 LT	41	pptr = kmap(page);
	42	curr = pptr + (offset & (PAGE_CACHE_BITS - 1)) / 32;
	43	i = offset % 32;
	44	offset &= ~(PAGE_CACHE_BITS - 1);
	45	if ((size ^ offset) / PAGE_CACHE_BITS)
	46	end = pptr + PAGE_CACHE_BITS / 32;
	47	else
	48	end = pptr + ((size + 31) & (PAGE_CACHE_BITS - 1)) / 32;
	49
	50	/* scan the first partial u32 for zero bits */
	51	val = *curr;
	52	if (~val) {
	53	n = be32_to_cpu(val);
	54	mask = (1U << 31) >> i;
	55	for (; i < 32; mask >>= 1, i++) {
	56	if (!(n & mask))
	57	goto found;
	58	}
	59	}
	60	curr++;
	61
	62	/* scan complete u32s for the first zero bit */
	63	while (1) {
	64	while (curr < end) {
	65	val = *curr;
	66	if (~val) {
	67	n = be32_to_cpu(val);
	68	mask = 1 << 31;
	69	for (i = 0; i < 32; mask >>= 1, i++) {
	70	if (!(n & mask))
	71	goto found;
	72	}
	73	}
	74	curr++;
	75	}
	76	kunmap(page);
	77	offset += PAGE_CACHE_BITS;
	78	if (offset >= size)
	79	break;
090d2b18 PE	80	page = read_mapping_page(mapping, offset / PAGE_CACHE_BITS,
090d2b18 PE	81	NULL);
649f1ee6 ES	82	if (IS_ERR(page)) {
	83	start = size;
	84	goto out;
	85	}
1da177e4 LT	86	curr = pptr = kmap(page);
	87	if ((size ^ offset) / PAGE_CACHE_BITS)
	88	end = pptr + PAGE_CACHE_BITS / 32;
	89	else
	90	end = pptr + ((size + 31) & (PAGE_CACHE_BITS - 1)) / 32;
	91	}
	92	dprint(DBG_BITMAP, "bitmap full\n");
	93	start = size;
	94	goto out;
	95
	96	found:
	97	start = offset + (curr - pptr) * 32 + i;
	98	if (start >= size) {
	99	dprint(DBG_BITMAP, "bitmap full\n");
	100	goto out;
	101	}
	102	/* do any partial u32 at the start */
	103	len = min(size - start, len);
	104	while (1) {
	105	n \|= mask;
	106	if (++i >= 32)
	107	break;
	108	mask >>= 1;
	109	if (!--len \|\| n & mask)
	110	goto done;
	111	}
	112	if (!--len)
	113	goto done;
	114	*curr++ = cpu_to_be32(n);
	115	/* do full u32s */
	116	while (1) {
	117	while (curr < end) {
	118	n = be32_to_cpu(*curr);
	119	if (len < 32)
	120	goto last;
	121	if (n) {
	122	len = 32;
	123	goto last;
	124	}
	125	*curr++ = cpu_to_be32(0xffffffff);
	126	len -= 32;
	127	}
	128	set_page_dirty(page);
	129	kunmap(page);
	130	offset += PAGE_CACHE_BITS;
090d2b18 PE	131	page = read_mapping_page(mapping, offset / PAGE_CACHE_BITS,
090d2b18 PE	132	NULL);
649f1ee6 ES	133	if (IS_ERR(page)) {
	134	start = size;
	135	goto out;
	136	}
1da177e4 LT	137	pptr = kmap(page);
	138	curr = pptr;
	139	end = pptr + PAGE_CACHE_BITS / 32;
	140	}
	141	last:
	142	/* do any partial u32 at end */
	143	mask = 1U << 31;
	144	for (i = 0; i < len; i++) {
	145	if (n & mask)
	146	break;
	147	n \|= mask;
	148	mask >>= 1;
	149	}
	150	done:
	151	*curr = cpu_to_be32(n);
	152	set_page_dirty(page);
	153	kunmap(page);
	154	max = offset + (curr - pptr) 32 + i - start;
dd73a01a	155	sbi->free_blocks -= *max;
1da177e4 LT	156	sb->s_dirt = 1;
	157	dprint(DBG_BITMAP, "-> %u,%u\n", start, *max);
	158	out:
dd73a01a	159	mutex_unlock(&sbi->alloc_mutex);
1da177e4 LT	160	return start;
	161	}
	162
	163	int hfsplus_block_free(struct super_block *sb, u32 offset, u32 count)
	164	{
dd73a01a	165	struct hfsplus_sb_info *sbi = HFSPLUS_SB(sb);
1da177e4 LT	166	struct page *page;
	167	struct address_space *mapping;
	168	__be32 pptr, curr, *end;
	169	u32 mask, len, pnr;
	170	int i;
	171
	172	/* is there any actual work to be done? */
	173	if (!count)
	174	return 0;
	175
	176	dprint(DBG_BITMAP, "block_free: %u,%u\n", offset, count);
	177	/* are all of the bits in range? */
dd73a01a	178	if ((offset + count) > sbi->total_blocks)
1da177e4 LT	179	return -2;
1da177e4 LT	180
dd73a01a CH	181	mutex_lock(&sbi->alloc_mutex);
dd73a01a CH	182	mapping = sbi->alloc_file->i_mapping;
1da177e4	183	pnr = offset / PAGE_CACHE_BITS;
090d2b18	184	page = read_mapping_page(mapping, pnr, NULL);
1da177e4 LT	185	pptr = kmap(page);
	186	curr = pptr + (offset & (PAGE_CACHE_BITS - 1)) / 32;
	187	end = pptr + PAGE_CACHE_BITS / 32;
	188	len = count;
	189
	190	/* do any partial u32 at the start */
	191	i = offset % 32;
	192	if (i) {
	193	int j = 32 - i;
	194	mask = 0xffffffffU << j;
	195	if (j > count) {
	196	mask \|= 0xffffffffU >> (i + count);
	197	*curr++ &= cpu_to_be32(mask);
	198	goto out;
	199	}
	200	*curr++ &= cpu_to_be32(mask);
	201	count -= j;
	202	}
	203
	204	/* do full u32s */
	205	while (1) {
	206	while (curr < end) {
	207	if (count < 32)
	208	goto done;
	209	*curr++ = 0;
	210	count -= 32;
	211	}
	212	if (!count)
	213	break;
	214	set_page_dirty(page);
	215	kunmap(page);
090d2b18	216	page = read_mapping_page(mapping, ++pnr, NULL);
1da177e4 LT	217	pptr = kmap(page);
	218	curr = pptr;
	219	end = pptr + PAGE_CACHE_BITS / 32;
	220	}
	221	done:
	222	/* do any partial u32 at end */
	223	if (count) {
	224	mask = 0xffffffffU >> count;
	225	*curr &= cpu_to_be32(mask);
	226	}
	227	out:
	228	set_page_dirty(page);
	229	kunmap(page);
dd73a01a	230	sbi->free_blocks += len;
1da177e4	231	sb->s_dirt = 1;
dd73a01a	232	mutex_unlock(&sbi->alloc_mutex);
1da177e4 LT	233
	234	return 0;
	235	}