aboutsummaryrefslogtreecommitdiffstats
path: root/fs/ntfs/bitmap.c
blob: 12cf2e30c7dda9a2a8234af1c3b5a710f85aab72 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
/*
 * bitmap.c - NTFS kernel bitmap handling.  Part of the Linux-NTFS project.
 *
 * Copyright (c) 2004 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--) {
			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 */