[net-next-2.6.git] / fs / ntfs / bitmap.c

/*
 * bitmap.c - NTFS kernel bitmap handling.  Part of the Linux-NTFS project.
 *
 * Copyright (c) 2004-2005 Anton Altaparmakov
 *
 * This program/include file is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as published
 * by the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program/include file 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 (in the main directory of the Linux-NTFS
 * distribution in the file COPYING); if not, write to the Free Software
 * Foundation,Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

#ifdef NTFS_RW

#include <linux/pagemap.h>

#include "bitmap.h"
#include "debug.h"
#include "aops.h"
#include "ntfs.h"

/**
 * __ntfs_bitmap_set_bits_in_run - set a run of bits in a bitmap to a value
 * @vi:			vfs inode describing the bitmap
 * @start_bit:		first bit to set
 * @count:		number of bits to set
 * @value:		value to set the bits to (i.e. 0 or 1)
 * @is_rollback:	if 'true' this is a rollback operation
 *
 * Set @count bits starting at bit @start_bit in the bitmap described by the
 * vfs inode @vi to @value, where @value is either 0 or 1.
 *
 * @is_rollback should always be 'false', it is for internal use to rollback
 * errors.  You probably want to use ntfs_bitmap_set_bits_in_run() instead.
 *
 * Return 0 on success and -errno on error.
 */
int __ntfs_bitmap_set_bits_in_run(struct inode *vi, const s64 start_bit,
		const s64 count, const u8 value, const bool is_rollback)
{
	s64 cnt = count;
	pgoff_t index, end_index;
	struct address_space *mapping;
	struct page *page;
	u8 *kaddr;
	int pos, len;
	u8 bit;

	BUG_ON(!vi);
	ntfs_debug("Entering for i_ino 0x%lx, start_bit 0x%llx, count 0x%llx, "
			"value %u.%s", vi->i_ino, (unsigned long long)start_bit,
			(unsigned long long)cnt, (unsigned int)value,
			is_rollback ? " (rollback)" : "");
	BUG_ON(start_bit < 0);
	BUG_ON(cnt < 0);
	BUG_ON(value > 1);
	/*
	 * Calculate the indices for the pages containing the first and last
	 * bits, i.e. @start_bit and @start_bit + @cnt - 1, respectively.
	 */
	index = start_bit >> (3 + PAGE_CACHE_SHIFT);
	end_index = (start_bit + cnt - 1) >> (3 + PAGE_CACHE_SHIFT);

	/* Get the page containing the first bit (@start_bit). */
	mapping = vi->i_mapping;
	page = ntfs_map_page(mapping, index);
	if (IS_ERR(page)) {
		if (!is_rollback)
			ntfs_error(vi->i_sb, "Failed to map first page (error "
					"%li), aborting.", PTR_ERR(page));
		return PTR_ERR(page);
	}
	kaddr = page_address(page);

	/* Set @pos to the position of the byte containing @start_bit. */
	pos = (start_bit >> 3) & ~PAGE_CACHE_MASK;

	/* Calculate the position of @start_bit in the first byte. */
	bit = start_bit & 7;

	/* If the first byte is partial, modify the appropriate bits in it. */
	if (bit) {
		u8 *byte = kaddr + pos;
		while ((bit & 7) && cnt) {
			cnt--;
			if (value)
				*byte |= 1 << bit++;
			else
				*byte &= ~(1 << bit++);
		}
		/* If we are done, unmap the page and return success. */
		if (!cnt)
			goto done;

		/* Update @pos to the new position. */
		pos++;
	}
	/*
	 * Depending on @value, modify all remaining whole bytes in the page up
	 * to @cnt.
	 */
	len = min_t(s64, cnt >> 3, PAGE_CACHE_SIZE - pos);
	memset(kaddr + pos, value ? 0xff : 0, len);
	cnt -= len << 3;

	/* Update @len to point to the first not-done byte in the page. */
	if (cnt < 8)
		len += pos;

	/* If we are not in the last page, deal with all subsequent pages. */
	while (index < end_index) {
		BUG_ON(cnt <= 0);

		/* Update @index and get the next page. */
		flush_dcache_page(page);
		set_page_dirty(page);
		ntfs_unmap_page(page);
		page = ntfs_map_page(mapping, ++index);
		if (IS_ERR(page))
			goto rollback;
		kaddr = page_address(page);
		/*
		 * Depending on @value, modify all remaining whole bytes in the
		 * page up to @cnt.
		 */
		len = min_t(s64, cnt >> 3, PAGE_CACHE_SIZE);
		memset(kaddr, value ? 0xff : 0, len);
		cnt -= len << 3;
	}
	/*
	 * The currently mapped page is the last one.  If the last byte is
	 * partial, modify the appropriate bits in it.  Note, @len is the
	 * position of the last byte inside the page.
	 */
	if (cnt) {
		u8 *byte;

		BUG_ON(cnt > 7);

		bit = cnt;
		byte = kaddr + len;
		while (bit--) {
			if (value)
				*byte |= 1 << bit;
			else
				*byte &= ~(1 << bit);
		}
	}
done:
	/* We are done.  Unmap the page and return success. */
	flush_dcache_page(page);
	set_page_dirty(page);
	ntfs_unmap_page(page);
	ntfs_debug("Done.");
	return 0;
rollback:
	/*
	 * Current state:
	 *	- no pages are mapped
	 *	- @count - @cnt is the number of bits that have been modified
	 */
	if (is_rollback)
		return PTR_ERR(page);
	if (count != cnt)
		pos = __ntfs_bitmap_set_bits_in_run(vi, start_bit, count - cnt,
				value ? 0 : 1, true);
	else
		pos = 0;
	if (!pos) {
		/* Rollback was successful. */
		ntfs_error(vi->i_sb, "Failed to map subsequent page (error "
				"%li), aborting.", PTR_ERR(page));
	} else {
		/* Rollback failed. */
		ntfs_error(vi->i_sb, "Failed to map subsequent page (error "
				"%li) and rollback failed (error %i).  "
				"Aborting and leaving inconsistent metadata.  "
				"Unmount and run chkdsk.", PTR_ERR(page), pos);
		NVolSetErrors(NTFS_SB(vi->i_sb));
	}
	return PTR_ERR(page);
}

#endif /* NTFS_RW */
Commit	Line	Data
1da177e4 LT	1	/*
	2	* bitmap.c - NTFS kernel bitmap handling. Part of the Linux-NTFS project.
	3	*
18efefa9	4	* Copyright (c) 2004-2005 Anton Altaparmakov
1da177e4 LT	5	*
	6	* This program/include file is free software; you can redistribute it and/or
	7	* modify it under the terms of the GNU General Public License as published
	8	* by the Free Software Foundation; either version 2 of the License, or
	9	* (at your option) any later version.
	10	*
	11	* This program/include file is distributed in the hope that it will be
	12	* useful, but WITHOUT ANY WARRANTY; without even the implied warranty
	13	* of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	14	* GNU General Public License for more details.
	15	*
	16	* You should have received a copy of the GNU General Public License
	17	* along with this program (in the main directory of the Linux-NTFS
	18	* distribution in the file COPYING); if not, write to the Free Software
	19	* Foundation,Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
	20	*/
	21
	22	#ifdef NTFS_RW
	23
	24	#include <linux/pagemap.h>
	25
	26	#include "bitmap.h"
	27	#include "debug.h"
	28	#include "aops.h"
	29	#include "ntfs.h"
	30
	31	/**
	32	* __ntfs_bitmap_set_bits_in_run - set a run of bits in a bitmap to a value
	33	* @vi: vfs inode describing the bitmap
	34	* @start_bit: first bit to set
	35	* @count: number of bits to set
	36	* @value: value to set the bits to (i.e. 0 or 1)
c49c3111	37	* @is_rollback: if 'true' this is a rollback operation
1da177e4 LT	38	*
	39	* Set @count bits starting at bit @start_bit in the bitmap described by the
	40	* vfs inode @vi to @value, where @value is either 0 or 1.
	41	*
c49c3111	42	* @is_rollback should always be 'false', it is for internal use to rollback
1da177e4 LT	43	* errors. You probably want to use ntfs_bitmap_set_bits_in_run() instead.
	44	*
	45	* Return 0 on success and -errno on error.
	46	*/
	47	int __ntfs_bitmap_set_bits_in_run(struct inode *vi, const s64 start_bit,
c49c3111	48	const s64 count, const u8 value, const bool is_rollback)
1da177e4 LT	49	{
	50	s64 cnt = count;
	51	pgoff_t index, end_index;
	52	struct address_space *mapping;
	53	struct page *page;
	54	u8 *kaddr;
	55	int pos, len;
	56	u8 bit;
	57
	58	BUG_ON(!vi);
	59	ntfs_debug("Entering for i_ino 0x%lx, start_bit 0x%llx, count 0x%llx, "
	60	"value %u.%s", vi->i_ino, (unsigned long long)start_bit,
	61	(unsigned long long)cnt, (unsigned int)value,
	62	is_rollback ? " (rollback)" : "");
	63	BUG_ON(start_bit < 0);
	64	BUG_ON(cnt < 0);
	65	BUG_ON(value > 1);
	66	/*
	67	* Calculate the indices for the pages containing the first and last
	68	* bits, i.e. @start_bit and @start_bit + @cnt - 1, respectively.
	69	*/
	70	index = start_bit >> (3 + PAGE_CACHE_SHIFT);
	71	end_index = (start_bit + cnt - 1) >> (3 + PAGE_CACHE_SHIFT);
	72
	73	/* Get the page containing the first bit (@start_bit). */
	74	mapping = vi->i_mapping;
	75	page = ntfs_map_page(mapping, index);
	76	if (IS_ERR(page)) {
	77	if (!is_rollback)
	78	ntfs_error(vi->i_sb, "Failed to map first page (error "
	79	"%li), aborting.", PTR_ERR(page));
	80	return PTR_ERR(page);
	81	}
	82	kaddr = page_address(page);
	83
	84	/* Set @pos to the position of the byte containing @start_bit. */
	85	pos = (start_bit >> 3) & ~PAGE_CACHE_MASK;
	86
	87	/* Calculate the position of @start_bit in the first byte. */
	88	bit = start_bit & 7;
	89
	90	/* If the first byte is partial, modify the appropriate bits in it. */
	91	if (bit) {
	92	u8 *byte = kaddr + pos;
18efefa9 AA	93	while ((bit & 7) && cnt) {
18efefa9 AA	94	cnt--;
1da177e4 LT	95	if (value)
	96	*byte \|= 1 << bit++;
	97	else
	98	*byte &= ~(1 << bit++);
	99	}
	100	/* If we are done, unmap the page and return success. */
	101	if (!cnt)
	102	goto done;
	103
	104	/* Update @pos to the new position. */
	105	pos++;
	106	}
	107	/*
	108	* Depending on @value, modify all remaining whole bytes in the page up
	109	* to @cnt.
	110	*/
	111	len = min_t(s64, cnt >> 3, PAGE_CACHE_SIZE - pos);
	112	memset(kaddr + pos, value ? 0xff : 0, len);
	113	cnt -= len << 3;
	114
	115	/* Update @len to point to the first not-done byte in the page. */
	116	if (cnt < 8)
	117	len += pos;
	118
	119	/* If we are not in the last page, deal with all subsequent pages. */
	120	while (index < end_index) {
	121	BUG_ON(cnt <= 0);
	122
	123	/* Update @index and get the next page. */
	124	flush_dcache_page(page);
	125	set_page_dirty(page);
	126	ntfs_unmap_page(page);
	127	page = ntfs_map_page(mapping, ++index);
	128	if (IS_ERR(page))
	129	goto rollback;
	130	kaddr = page_address(page);
	131	/*
	132	* Depending on @value, modify all remaining whole bytes in the
	133	* page up to @cnt.
	134	*/
	135	len = min_t(s64, cnt >> 3, PAGE_CACHE_SIZE);
	136	memset(kaddr, value ? 0xff : 0, len);
	137	cnt -= len << 3;
	138	}
	139	/*
	140	* The currently mapped page is the last one. If the last byte is
	141	* partial, modify the appropriate bits in it. Note, @len is the
	142	* position of the last byte inside the page.
	143	*/
	144	if (cnt) {
	145	u8 *byte;
	146
	147	BUG_ON(cnt > 7);
	148
	149	bit = cnt;
	150	byte = kaddr + len;
	151	while (bit--) {
	152	if (value)
	153	*byte \|= 1 << bit;
	154	else
	155	*byte &= ~(1 << bit);
	156	}
	157	}
	158	done:
159	/* We are done. Unmap the page and return success. */
160	flush_dcache_page(page);
161	set_page_dirty(page);
162	ntfs_unmap_page(page);
163	ntfs_debug("Done.");
164	return 0;
165	rollback:
166	/*
167	* Current state:
168	* - no pages are mapped
169	* - @count - @cnt is the number of bits that have been modified
170	*/
171	if (is_rollback)
172	return PTR_ERR(page);
173	if (count != cnt)
174	pos = __ntfs_bitmap_set_bits_in_run(vi, start_bit, count - cnt,
c49c3111	175	value ? 0 : 1, true);
1da177e4 LT	176	else
	177	pos = 0;
	178	if (!pos) {
	179	/* Rollback was successful. */
	180	ntfs_error(vi->i_sb, "Failed to map subsequent page (error "
	181	"%li), aborting.", PTR_ERR(page));
	182	} else {
	183	/* Rollback failed. */
	184	ntfs_error(vi->i_sb, "Failed to map subsequent page (error "
	185	"%li) and rollback failed (error %i). "
	186	"Aborting and leaving inconsistent metadata. "
	187	"Unmount and run chkdsk.", PTR_ERR(page), pos);
	188	NVolSetErrors(NTFS_SB(vi->i_sb));
	189	}
	190	return PTR_ERR(page);
	191	}
	192
	193	#endif /* NTFS_RW */