1 | // SPDX-License-Identifier: GPL-2.0-or-later |
2 | /* |
3 | * bitmap.c - NTFS kernel bitmap handling. Part of the Linux-NTFS project. |
4 | * |
5 | * Copyright (c) 2004-2005 Anton Altaparmakov |
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) |
23 | * @is_rollback: if 'true' this is a rollback operation |
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 | * |
28 | * @is_rollback should always be 'false', it is for internal use to rollback |
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, |
34 | const s64 count, const u8 value, const bool is_rollback) |
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 | */ |
56 | index = start_bit >> (3 + PAGE_SHIFT); |
57 | end_index = (start_bit + cnt - 1) >> (3 + PAGE_SHIFT); |
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(ptr: 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(ptr: page); |
67 | } |
68 | kaddr = page_address(page); |
69 | |
70 | /* Set @pos to the position of the byte containing @start_bit. */ |
71 | pos = (start_bit >> 3) & ~PAGE_MASK; |
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; |
79 | while ((bit & 7) && cnt) { |
80 | cnt--; |
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 | */ |
97 | len = min_t(s64, cnt >> 3, PAGE_SIZE - pos); |
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: ++index); |
114 | if (IS_ERR(ptr: 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 | */ |
121 | len = min_t(s64, cnt >> 3, PAGE_SIZE); |
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(ptr: page); |
159 | if (count != cnt) |
160 | pos = __ntfs_bitmap_set_bits_in_run(vi, start_bit, count: count - cnt, |
161 | value: value ? 0 : 1, is_rollback: true); |
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(vol: NTFS_SB(sb: vi->i_sb)); |
175 | } |
176 | return PTR_ERR(ptr: page); |
177 | } |
178 | |
179 | #endif /* NTFS_RW */ |
180 | |