1 /*
2 * bitmap.c - NTFS kernel bitmap handling. Part of the Linux-NTFS project.
3 *
4 * Copyright (c) 2004-2005 Anton Altaparmakov
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)
37 * @is_rollback: if 'true' this is a rollback operation
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 *
42 * @is_rollback should always be 'false', it is for internal use to rollback
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 */
__ntfs_bitmap_set_bits_in_run(struct inode * vi,const s64 start_bit,const s64 count,const u8 value,const bool is_rollback)47 int __ntfs_bitmap_set_bits_in_run(struct inode *vi, const s64 start_bit,
48 const s64 count, const u8 value, const bool is_rollback)
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;
93 while ((bit & 7) && cnt) {
94 cnt--;
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,
175 value ? 0 : 1, true);
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 */
194