2 * bitmap.c - NTFS kernel bitmap handling. Part of the Linux-NTFS project.
4 * Copyright (c) 2004-2005 Anton Altaparmakov
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.
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.
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
24 #include <linux/pagemap.h>
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
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.
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.
45 * Return 0 on success and -errno on error.
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)
51 pgoff_t index, end_index;
52 struct address_space *mapping;
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);
67 * Calculate the indices for the pages containing the first and last
68 * bits, i.e. @start_bit and @start_bit + @cnt - 1, respectively.
70 index = start_bit >> (3 + PAGE_CACHE_SHIFT);
71 end_index = (start_bit + cnt - 1) >> (3 + PAGE_CACHE_SHIFT);
73 /* Get the page containing the first bit (@start_bit). */
74 mapping = vi->i_mapping;
75 page = ntfs_map_page(mapping, index);
78 ntfs_error(vi->i_sb, "Failed to map first page (error "
79 "%li), aborting.", PTR_ERR(page));
82 kaddr = page_address(page);
84 /* Set @pos to the position of the byte containing @start_bit. */
85 pos = (start_bit >> 3) & ~PAGE_CACHE_MASK;
87 /* Calculate the position of @start_bit in the first byte. */
90 /* If the first byte is partial, modify the appropriate bits in it. */
92 u8 *byte = kaddr + pos;
93 while ((bit & 7) && cnt) {
98 *byte &= ~(1 << bit++);
100 /* If we are done, unmap the page and return success. */
104 /* Update @pos to the new position. */
108 * Depending on @value, modify all remaining whole bytes in the page up
111 len = min_t(s64, cnt >> 3, PAGE_CACHE_SIZE - pos);
112 memset(kaddr + pos, value ? 0xff : 0, len);
115 /* Update @len to point to the first not-done byte in the page. */
119 /* If we are not in the last page, deal with all subsequent pages. */
120 while (index < end_index) {
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);
130 kaddr = page_address(page);
132 * Depending on @value, modify all remaining whole bytes in the
135 len = min_t(s64, cnt >> 3, PAGE_CACHE_SIZE);
136 memset(kaddr, value ? 0xff : 0, len);
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.
155 *byte &= ~(1 << bit);
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);
168 * - no pages are mapped
169 * - @count - @cnt is the number of bits that have been modified
172 return PTR_ERR(page);
174 pos = __ntfs_bitmap_set_bits_in_run(vi, start_bit, count - cnt,
175 value ? 0 : 1, TRUE);
179 /* Rollback was successful. */
180 ntfs_error(vi->i_sb, "Failed to map subsequent page (error "
181 "%li), aborting.", PTR_ERR(page));
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));
190 return PTR_ERR(page);