[net-next-2.6.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
	18	int hfsplus_block_allocate(struct super_block sb, u32 size, u32 offset, u32 max)
	19	{
dd73a01a	20	struct hfsplus_sb_info *sbi = HFSPLUS_SB(sb);
1da177e4 LT	21	struct page *page;
	22	struct address_space *mapping;
	23	__be32 pptr, curr, *end;
	24	u32 mask, start, len, n;
	25	__be32 val;
	26	int i;
	27
	28	len = *max;
	29	if (!len)
	30	return size;
	31
	32	dprint(DBG_BITMAP, "block_allocate: %u,%u,%u\n", size, offset, len);
dd73a01a CH	33	mutex_lock(&sbi->alloc_mutex);
dd73a01a CH	34	mapping = sbi->alloc_file->i_mapping;
090d2b18	35	page = read_mapping_page(mapping, offset / PAGE_CACHE_BITS, NULL);
649f1ee6 ES	36	if (IS_ERR(page)) {
	37	start = size;
	38	goto out;
	39	}
1da177e4 LT	40	pptr = kmap(page);
	41	curr = pptr + (offset & (PAGE_CACHE_BITS - 1)) / 32;
	42	i = offset % 32;
	43	offset &= ~(PAGE_CACHE_BITS - 1);
	44	if ((size ^ offset) / PAGE_CACHE_BITS)
	45	end = pptr + PAGE_CACHE_BITS / 32;
	46	else
	47	end = pptr + ((size + 31) & (PAGE_CACHE_BITS - 1)) / 32;
	48
	49	/* scan the first partial u32 for zero bits */
	50	val = *curr;
	51	if (~val) {
	52	n = be32_to_cpu(val);
	53	mask = (1U << 31) >> i;
	54	for (; i < 32; mask >>= 1, i++) {
	55	if (!(n & mask))
	56	goto found;
	57	}
	58	}
	59	curr++;
	60
	61	/* scan complete u32s for the first zero bit */
	62	while (1) {
	63	while (curr < end) {
	64	val = *curr;
	65	if (~val) {
	66	n = be32_to_cpu(val);
	67	mask = 1 << 31;
	68	for (i = 0; i < 32; mask >>= 1, i++) {
	69	if (!(n & mask))
	70	goto found;
	71	}
	72	}
	73	curr++;
	74	}
	75	kunmap(page);
	76	offset += PAGE_CACHE_BITS;
	77	if (offset >= size)
	78	break;
090d2b18 PE	79	page = read_mapping_page(mapping, offset / PAGE_CACHE_BITS,
090d2b18 PE	80	NULL);
649f1ee6 ES	81	if (IS_ERR(page)) {
	82	start = size;
	83	goto out;
	84	}
1da177e4 LT	85	curr = pptr = kmap(page);
	86	if ((size ^ offset) / PAGE_CACHE_BITS)
	87	end = pptr + PAGE_CACHE_BITS / 32;
	88	else
	89	end = pptr + ((size + 31) & (PAGE_CACHE_BITS - 1)) / 32;
	90	}
	91	dprint(DBG_BITMAP, "bitmap full\n");
	92	start = size;
	93	goto out;
	94
	95	found:
	96	start = offset + (curr - pptr) * 32 + i;
	97	if (start >= size) {
	98	dprint(DBG_BITMAP, "bitmap full\n");
	99	goto out;
	100	}
	101	/* do any partial u32 at the start */
	102	len = min(size - start, len);
	103	while (1) {
	104	n \|= mask;
	105	if (++i >= 32)
	106	break;
	107	mask >>= 1;
	108	if (!--len \|\| n & mask)
	109	goto done;
	110	}
	111	if (!--len)
	112	goto done;
	113	*curr++ = cpu_to_be32(n);
	114	/* do full u32s */
	115	while (1) {
	116	while (curr < end) {
	117	n = be32_to_cpu(*curr);
	118	if (len < 32)
	119	goto last;
	120	if (n) {
	121	len = 32;
	122	goto last;
	123	}
	124	*curr++ = cpu_to_be32(0xffffffff);
	125	len -= 32;
	126	}
	127	set_page_dirty(page);
	128	kunmap(page);
	129	offset += PAGE_CACHE_BITS;
090d2b18 PE	130	page = read_mapping_page(mapping, offset / PAGE_CACHE_BITS,
090d2b18 PE	131	NULL);
649f1ee6 ES	132	if (IS_ERR(page)) {
	133	start = size;
	134	goto out;
	135	}
1da177e4 LT	136	pptr = kmap(page);
	137	curr = pptr;
	138	end = pptr + PAGE_CACHE_BITS / 32;
	139	}
	140	last:
	141	/* do any partial u32 at end */
	142	mask = 1U << 31;
	143	for (i = 0; i < len; i++) {
	144	if (n & mask)
	145	break;
	146	n \|= mask;
	147	mask >>= 1;
	148	}
	149	done:
	150	*curr = cpu_to_be32(n);
	151	set_page_dirty(page);
	152	kunmap(page);
	153	max = offset + (curr - pptr) 32 + i - start;
dd73a01a	154	sbi->free_blocks -= *max;
1da177e4 LT	155	sb->s_dirt = 1;
	156	dprint(DBG_BITMAP, "-> %u,%u\n", start, *max);
	157	out:
dd73a01a	158	mutex_unlock(&sbi->alloc_mutex);
1da177e4 LT	159	return start;
	160	}
	161
	162	int hfsplus_block_free(struct super_block *sb, u32 offset, u32 count)
	163	{
dd73a01a	164	struct hfsplus_sb_info *sbi = HFSPLUS_SB(sb);
1da177e4 LT	165	struct page *page;
	166	struct address_space *mapping;
	167	__be32 pptr, curr, *end;
	168	u32 mask, len, pnr;
	169	int i;
	170
	171	/* is there any actual work to be done? */
	172	if (!count)
	173	return 0;
	174
	175	dprint(DBG_BITMAP, "block_free: %u,%u\n", offset, count);
	176	/* are all of the bits in range? */
dd73a01a	177	if ((offset + count) > sbi->total_blocks)
1da177e4 LT	178	return -2;
1da177e4 LT	179
dd73a01a CH	180	mutex_lock(&sbi->alloc_mutex);
dd73a01a CH	181	mapping = sbi->alloc_file->i_mapping;
1da177e4	182	pnr = offset / PAGE_CACHE_BITS;
090d2b18	183	page = read_mapping_page(mapping, pnr, NULL);
1da177e4 LT	184	pptr = kmap(page);
	185	curr = pptr + (offset & (PAGE_CACHE_BITS - 1)) / 32;
	186	end = pptr + PAGE_CACHE_BITS / 32;
	187	len = count;
	188
	189	/* do any partial u32 at the start */
	190	i = offset % 32;
	191	if (i) {
	192	int j = 32 - i;
	193	mask = 0xffffffffU << j;
	194	if (j > count) {
	195	mask \|= 0xffffffffU >> (i + count);
	196	*curr++ &= cpu_to_be32(mask);
	197	goto out;
	198	}
	199	*curr++ &= cpu_to_be32(mask);
	200	count -= j;
	201	}
	202
	203	/* do full u32s */
	204	while (1) {
	205	while (curr < end) {
	206	if (count < 32)
	207	goto done;
	208	*curr++ = 0;
	209	count -= 32;
	210	}
	211	if (!count)
	212	break;
	213	set_page_dirty(page);
	214	kunmap(page);
090d2b18	215	page = read_mapping_page(mapping, ++pnr, NULL);
1da177e4 LT	216	pptr = kmap(page);
	217	curr = pptr;
	218	end = pptr + PAGE_CACHE_BITS / 32;
	219	}
	220	done:
	221	/* do any partial u32 at end */
	222	if (count) {
	223	mask = 0xffffffffU >> count;
	224	*curr &= cpu_to_be32(mask);
	225	}
	226	out:
	227	set_page_dirty(page);
	228	kunmap(page);
dd73a01a	229	sbi->free_blocks += len;
1da177e4	230	sb->s_dirt = 1;
dd73a01a	231	mutex_unlock(&sbi->alloc_mutex);
1da177e4 LT	232
	233	return 0;
	234	}