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a1d312de | 1 | // SPDX-License-Identifier: GPL-2.0-or-later |
1da177e4 LT |
2 | /* |
3 | * bitmap.c - NTFS kernel bitmap handling. Part of the Linux-NTFS project. | |
4 | * | |
18efefa9 | 5 | * Copyright (c) 2004-2005 Anton Altaparmakov |
1da177e4 LT |
6 | */ |
7 | ||
8 | #ifdef NTFS_RW | |
9 | ||
10 | #include <linux/pagemap.h> | |
11 | ||
12 | #include "bitmap.h" | |
13 | #include "debug.h" | |
14 | #include "aops.h" | |
15 | #include "ntfs.h" | |
16 | ||
17 | /** | |
18 | * __ntfs_bitmap_set_bits_in_run - set a run of bits in a bitmap to a value | |
19 | * @vi: vfs inode describing the bitmap | |
20 | * @start_bit: first bit to set | |
21 | * @count: number of bits to set | |
22 | * @value: value to set the bits to (i.e. 0 or 1) | |
c49c3111 | 23 | * @is_rollback: if 'true' this is a rollback operation |
1da177e4 LT |
24 | * |
25 | * Set @count bits starting at bit @start_bit in the bitmap described by the | |
26 | * vfs inode @vi to @value, where @value is either 0 or 1. | |
27 | * | |
c49c3111 | 28 | * @is_rollback should always be 'false', it is for internal use to rollback |
1da177e4 LT |
29 | * errors. You probably want to use ntfs_bitmap_set_bits_in_run() instead. |
30 | * | |
31 | * Return 0 on success and -errno on error. | |
32 | */ | |
33 | int __ntfs_bitmap_set_bits_in_run(struct inode *vi, const s64 start_bit, | |
c49c3111 | 34 | const s64 count, const u8 value, const bool is_rollback) |
1da177e4 LT |
35 | { |
36 | s64 cnt = count; | |
37 | pgoff_t index, end_index; | |
38 | struct address_space *mapping; | |
39 | struct page *page; | |
40 | u8 *kaddr; | |
41 | int pos, len; | |
42 | u8 bit; | |
43 | ||
44 | BUG_ON(!vi); | |
45 | ntfs_debug("Entering for i_ino 0x%lx, start_bit 0x%llx, count 0x%llx, " | |
46 | "value %u.%s", vi->i_ino, (unsigned long long)start_bit, | |
47 | (unsigned long long)cnt, (unsigned int)value, | |
48 | is_rollback ? " (rollback)" : ""); | |
49 | BUG_ON(start_bit < 0); | |
50 | BUG_ON(cnt < 0); | |
51 | BUG_ON(value > 1); | |
52 | /* | |
53 | * Calculate the indices for the pages containing the first and last | |
54 | * bits, i.e. @start_bit and @start_bit + @cnt - 1, respectively. | |
55 | */ | |
09cbfeaf KS |
56 | index = start_bit >> (3 + PAGE_SHIFT); |
57 | end_index = (start_bit + cnt - 1) >> (3 + PAGE_SHIFT); | |
1da177e4 LT |
58 | |
59 | /* Get the page containing the first bit (@start_bit). */ | |
60 | mapping = vi->i_mapping; | |
61 | page = ntfs_map_page(mapping, index); | |
62 | if (IS_ERR(page)) { | |
63 | if (!is_rollback) | |
64 | ntfs_error(vi->i_sb, "Failed to map first page (error " | |
65 | "%li), aborting.", PTR_ERR(page)); | |
66 | return PTR_ERR(page); | |
67 | } | |
68 | kaddr = page_address(page); | |
69 | ||
70 | /* Set @pos to the position of the byte containing @start_bit. */ | |
09cbfeaf | 71 | pos = (start_bit >> 3) & ~PAGE_MASK; |
1da177e4 LT |
72 | |
73 | /* Calculate the position of @start_bit in the first byte. */ | |
74 | bit = start_bit & 7; | |
75 | ||
76 | /* If the first byte is partial, modify the appropriate bits in it. */ | |
77 | if (bit) { | |
78 | u8 *byte = kaddr + pos; | |
18efefa9 AA |
79 | while ((bit & 7) && cnt) { |
80 | cnt--; | |
1da177e4 LT |
81 | if (value) |
82 | *byte |= 1 << bit++; | |
83 | else | |
84 | *byte &= ~(1 << bit++); | |
85 | } | |
86 | /* If we are done, unmap the page and return success. */ | |
87 | if (!cnt) | |
88 | goto done; | |
89 | ||
90 | /* Update @pos to the new position. */ | |
91 | pos++; | |
92 | } | |
93 | /* | |
94 | * Depending on @value, modify all remaining whole bytes in the page up | |
95 | * to @cnt. | |
96 | */ | |
09cbfeaf | 97 | len = min_t(s64, cnt >> 3, PAGE_SIZE - pos); |
1da177e4 LT |
98 | memset(kaddr + pos, value ? 0xff : 0, len); |
99 | cnt -= len << 3; | |
100 | ||
101 | /* Update @len to point to the first not-done byte in the page. */ | |
102 | if (cnt < 8) | |
103 | len += pos; | |
104 | ||
105 | /* If we are not in the last page, deal with all subsequent pages. */ | |
106 | while (index < end_index) { | |
107 | BUG_ON(cnt <= 0); | |
108 | ||
109 | /* Update @index and get the next page. */ | |
110 | flush_dcache_page(page); | |
111 | set_page_dirty(page); | |
112 | ntfs_unmap_page(page); | |
113 | page = ntfs_map_page(mapping, ++index); | |
114 | if (IS_ERR(page)) | |
115 | goto rollback; | |
116 | kaddr = page_address(page); | |
117 | /* | |
118 | * Depending on @value, modify all remaining whole bytes in the | |
119 | * page up to @cnt. | |
120 | */ | |
09cbfeaf | 121 | len = min_t(s64, cnt >> 3, PAGE_SIZE); |
1da177e4 LT |
122 | memset(kaddr, value ? 0xff : 0, len); |
123 | cnt -= len << 3; | |
124 | } | |
125 | /* | |
126 | * The currently mapped page is the last one. If the last byte is | |
127 | * partial, modify the appropriate bits in it. Note, @len is the | |
128 | * position of the last byte inside the page. | |
129 | */ | |
130 | if (cnt) { | |
131 | u8 *byte; | |
132 | ||
133 | BUG_ON(cnt > 7); | |
134 | ||
135 | bit = cnt; | |
136 | byte = kaddr + len; | |
137 | while (bit--) { | |
138 | if (value) | |
139 | *byte |= 1 << bit; | |
140 | else | |
141 | *byte &= ~(1 << bit); | |
142 | } | |
143 | } | |
144 | done: | |
145 | /* We are done. Unmap the page and return success. */ | |
146 | flush_dcache_page(page); | |
147 | set_page_dirty(page); | |
148 | ntfs_unmap_page(page); | |
149 | ntfs_debug("Done."); | |
150 | return 0; | |
151 | rollback: | |
152 | /* | |
153 | * Current state: | |
154 | * - no pages are mapped | |
155 | * - @count - @cnt is the number of bits that have been modified | |
156 | */ | |
157 | if (is_rollback) | |
158 | return PTR_ERR(page); | |
159 | if (count != cnt) | |
160 | pos = __ntfs_bitmap_set_bits_in_run(vi, start_bit, count - cnt, | |
c49c3111 | 161 | value ? 0 : 1, true); |
1da177e4 LT |
162 | else |
163 | pos = 0; | |
164 | if (!pos) { | |
165 | /* Rollback was successful. */ | |
166 | ntfs_error(vi->i_sb, "Failed to map subsequent page (error " | |
167 | "%li), aborting.", PTR_ERR(page)); | |
168 | } else { | |
169 | /* Rollback failed. */ | |
170 | ntfs_error(vi->i_sb, "Failed to map subsequent page (error " | |
171 | "%li) and rollback failed (error %i). " | |
172 | "Aborting and leaving inconsistent metadata. " | |
173 | "Unmount and run chkdsk.", PTR_ERR(page), pos); | |
174 | NVolSetErrors(NTFS_SB(vi->i_sb)); | |
175 | } | |
176 | return PTR_ERR(page); | |
177 | } | |
178 | ||
179 | #endif /* NTFS_RW */ |