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(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. */ 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); 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 */ 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(page); 159 if (count != cnt) 160 pos = __ntfs_bitmap_set_bits_in_run(vi, start_bit, count - cnt, 161 value ? 0 : 1, 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(NTFS_SB(vi->i_sb)); 175 } 176 return PTR_ERR(page); 177 } 178 179 #endif /* NTFS_RW */ 180