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

/*
 *  linux/fs/hfsplus/bitmap.c
 *
 * Copyright (C) 2001
 * Brad Boyer ([email protected])
 * (C) 2003 Ardis Technologies <[email protected]>
 *
 * 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 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(&HFSPLUS_SB(sb).alloc_file->i_mutex);
	mapping = HFSPLUS_SB(sb).alloc_file->i_mapping;
	page = read_mapping_page(mapping, offset / PAGE_CACHE_BITS, NULL);
	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);
		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);
		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;
	HFSPLUS_SB(sb).free_blocks -= *max;
	sb->s_dirt = 1;
	dprint(DBG_BITMAP, "-> %u,%u\n", start, *max);
out:
	mutex_unlock(&HFSPLUS_SB(sb).alloc_file->i_mutex);
	return start;
}

int hfsplus_block_free(struct super_block *sb, u32 offset, u32 count)
{
	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) > HFSPLUS_SB(sb).total_blocks)
		return -2;

	mutex_lock(&HFSPLUS_SB(sb).alloc_file->i_mutex);
	mapping = HFSPLUS_SB(sb).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);
	HFSPLUS_SB(sb).free_blocks += len;
	sb->s_dirt = 1;
	mutex_unlock(&HFSPLUS_SB(sb).alloc_file->i_mutex);

	return 0;
}
Commit	Line	Data
1da177e4 LT	1	/*
	2	* linux/fs/hfsplus/bitmap.c
	3	*
	4	* Copyright (C) 2001
	5	* Brad Boyer ([email protected])
	6	* (C) 2003 Ardis Technologies <[email protected]>
	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	{
	20	struct page *page;
	21	struct address_space *mapping;
	22	__be32 pptr, curr, *end;
	23	u32 mask, start, len, n;
	24	__be32 val;
	25	int i;
	26
	27	len = *max;
	28	if (!len)
	29	return size;
	30
	31	dprint(DBG_BITMAP, "block_allocate: %u,%u,%u\n", size, offset, len);
1b1dcc1b	32	mutex_lock(&HFSPLUS_SB(sb).alloc_file->i_mutex);
1da177e4	33	mapping = HFSPLUS_SB(sb).alloc_file->i_mapping;
090d2b18	34	page = read_mapping_page(mapping, offset / PAGE_CACHE_BITS, NULL);
1da177e4 LT	35	pptr = kmap(page);
	36	curr = pptr + (offset & (PAGE_CACHE_BITS - 1)) / 32;
	37	i = offset % 32;
	38	offset &= ~(PAGE_CACHE_BITS - 1);
	39	if ((size ^ offset) / PAGE_CACHE_BITS)
	40	end = pptr + PAGE_CACHE_BITS / 32;
	41	else
	42	end = pptr + ((size + 31) & (PAGE_CACHE_BITS - 1)) / 32;
	43
	44	/* scan the first partial u32 for zero bits */
	45	val = *curr;
	46	if (~val) {
	47	n = be32_to_cpu(val);
	48	mask = (1U << 31) >> i;
	49	for (; i < 32; mask >>= 1, i++) {
	50	if (!(n & mask))
	51	goto found;
	52	}
	53	}
	54	curr++;
	55
	56	/* scan complete u32s for the first zero bit */
	57	while (1) {
	58	while (curr < end) {
	59	val = *curr;
	60	if (~val) {
	61	n = be32_to_cpu(val);
	62	mask = 1 << 31;
	63	for (i = 0; i < 32; mask >>= 1, i++) {
	64	if (!(n & mask))
	65	goto found;
	66	}
	67	}
	68	curr++;
	69	}
	70	kunmap(page);
	71	offset += PAGE_CACHE_BITS;
	72	if (offset >= size)
	73	break;
090d2b18 PE	74	page = read_mapping_page(mapping, offset / PAGE_CACHE_BITS,
090d2b18 PE	75	NULL);
1da177e4 LT	76	curr = pptr = kmap(page);
	77	if ((size ^ offset) / PAGE_CACHE_BITS)
	78	end = pptr + PAGE_CACHE_BITS / 32;
	79	else
	80	end = pptr + ((size + 31) & (PAGE_CACHE_BITS - 1)) / 32;
	81	}
	82	dprint(DBG_BITMAP, "bitmap full\n");
	83	start = size;
	84	goto out;
	85
	86	found:
	87	start = offset + (curr - pptr) * 32 + i;
	88	if (start >= size) {
	89	dprint(DBG_BITMAP, "bitmap full\n");
	90	goto out;
	91	}
	92	/* do any partial u32 at the start */
	93	len = min(size - start, len);
	94	while (1) {
	95	n \|= mask;
	96	if (++i >= 32)
	97	break;
	98	mask >>= 1;
	99	if (!--len \|\| n & mask)
	100	goto done;
	101	}
	102	if (!--len)
	103	goto done;
	104	*curr++ = cpu_to_be32(n);
	105	/* do full u32s */
	106	while (1) {
	107	while (curr < end) {
	108	n = be32_to_cpu(*curr);
	109	if (len < 32)
	110	goto last;
	111	if (n) {
	112	len = 32;
	113	goto last;
	114	}
	115	*curr++ = cpu_to_be32(0xffffffff);
	116	len -= 32;
	117	}
	118	set_page_dirty(page);
	119	kunmap(page);
	120	offset += PAGE_CACHE_BITS;
090d2b18 PE	121	page = read_mapping_page(mapping, offset / PAGE_CACHE_BITS,
090d2b18 PE	122	NULL);
1da177e4 LT	123	pptr = kmap(page);
	124	curr = pptr;
	125	end = pptr + PAGE_CACHE_BITS / 32;
	126	}
	127	last:
	128	/* do any partial u32 at end */
	129	mask = 1U << 31;
	130	for (i = 0; i < len; i++) {
	131	if (n & mask)
	132	break;
	133	n \|= mask;
	134	mask >>= 1;
	135	}
	136	done:
	137	*curr = cpu_to_be32(n);
	138	set_page_dirty(page);
	139	kunmap(page);
	140	max = offset + (curr - pptr) 32 + i - start;
	141	HFSPLUS_SB(sb).free_blocks -= *max;
	142	sb->s_dirt = 1;
	143	dprint(DBG_BITMAP, "-> %u,%u\n", start, *max);
	144	out:
1b1dcc1b	145	mutex_unlock(&HFSPLUS_SB(sb).alloc_file->i_mutex);
1da177e4 LT	146	return start;
	147	}
	148
	149	int hfsplus_block_free(struct super_block *sb, u32 offset, u32 count)
	150	{
	151	struct page *page;
	152	struct address_space *mapping;
	153	__be32 pptr, curr, *end;
	154	u32 mask, len, pnr;
	155	int i;
	156
	157	/* is there any actual work to be done? */
	158	if (!count)
	159	return 0;
	160
	161	dprint(DBG_BITMAP, "block_free: %u,%u\n", offset, count);
	162	/* are all of the bits in range? */
	163	if ((offset + count) > HFSPLUS_SB(sb).total_blocks)
	164	return -2;
	165
1b1dcc1b	166	mutex_lock(&HFSPLUS_SB(sb).alloc_file->i_mutex);
1da177e4 LT	167	mapping = HFSPLUS_SB(sb).alloc_file->i_mapping;
1da177e4 LT	168	pnr = offset / PAGE_CACHE_BITS;
090d2b18	169	page = read_mapping_page(mapping, pnr, NULL);
1da177e4 LT	170	pptr = kmap(page);
	171	curr = pptr + (offset & (PAGE_CACHE_BITS - 1)) / 32;
	172	end = pptr + PAGE_CACHE_BITS / 32;
	173	len = count;
	174
	175	/* do any partial u32 at the start */
	176	i = offset % 32;
	177	if (i) {
	178	int j = 32 - i;
	179	mask = 0xffffffffU << j;
	180	if (j > count) {
	181	mask \|= 0xffffffffU >> (i + count);
	182	*curr++ &= cpu_to_be32(mask);
	183	goto out;
	184	}
	185	*curr++ &= cpu_to_be32(mask);
	186	count -= j;
	187	}
	188
	189	/* do full u32s */
	190	while (1) {
	191	while (curr < end) {
	192	if (count < 32)
	193	goto done;
	194	*curr++ = 0;
	195	count -= 32;
	196	}
	197	if (!count)
	198	break;
	199	set_page_dirty(page);
	200	kunmap(page);
090d2b18	201	page = read_mapping_page(mapping, ++pnr, NULL);
1da177e4 LT	202	pptr = kmap(page);
	203	curr = pptr;
	204	end = pptr + PAGE_CACHE_BITS / 32;
	205	}
	206	done:
	207	/* do any partial u32 at end */
	208	if (count) {
	209	mask = 0xffffffffU >> count;
	210	*curr &= cpu_to_be32(mask);
	211	}
	212	out:
	213	set_page_dirty(page);
	214	kunmap(page);
	215	HFSPLUS_SB(sb).free_blocks += len;
	216	sb->s_dirt = 1;
1b1dcc1b	217	mutex_unlock(&HFSPLUS_SB(sb).alloc_file->i_mutex);
1da177e4 LT	218
	219	return 0;
	220	}