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| 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 | */ |
| 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 |
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