194 lines
5.5 KiB
C
Executable File
194 lines
5.5 KiB
C
Executable File
/*
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* bitmap.c - NTFS kernel bitmap handling. Part of the Linux-NTFS project.
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*
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* Copyright (c) 2004-2005 Anton Altaparmakov
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*
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* This program/include file is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License as published
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* by the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program/include file is distributed in the hope that it will be
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* useful, but WITHOUT ANY WARRANTY; without even the implied warranty
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* of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program (in the main directory of the Linux-NTFS
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* distribution in the file COPYING); if not, write to the Free Software
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* Foundation,Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*/
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#ifdef NTFS_RW
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#include <linux/pagemap.h>
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#include "bitmap.h"
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#include "debug.h"
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#include "aops.h"
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#include "ntfs.h"
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/**
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* __ntfs_bitmap_set_bits_in_run - set a run of bits in a bitmap to a value
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* @vi: vfs inode describing the bitmap
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* @start_bit: first bit to set
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* @count: number of bits to set
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* @value: value to set the bits to (i.e. 0 or 1)
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* @is_rollback: if 'true' this is a rollback operation
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*
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* Set @count bits starting at bit @start_bit in the bitmap described by the
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* vfs inode @vi to @value, where @value is either 0 or 1.
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*
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* @is_rollback should always be 'false', it is for internal use to rollback
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* errors. You probably want to use ntfs_bitmap_set_bits_in_run() instead.
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*
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* Return 0 on success and -errno on error.
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*/
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int __ntfs_bitmap_set_bits_in_run(struct inode *vi, const s64 start_bit,
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const s64 count, const u8 value, const bool is_rollback)
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{
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s64 cnt = count;
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pgoff_t index, end_index;
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struct address_space *mapping;
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struct page *page;
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u8 *kaddr;
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int pos, len;
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u8 bit;
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BUG_ON(!vi);
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ntfs_debug("Entering for i_ino 0x%lx, start_bit 0x%llx, count 0x%llx, "
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"value %u.%s", vi->i_ino, (unsigned long long)start_bit,
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(unsigned long long)cnt, (unsigned int)value,
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is_rollback ? " (rollback)" : "");
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BUG_ON(start_bit < 0);
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BUG_ON(cnt < 0);
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BUG_ON(value > 1);
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/*
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* Calculate the indices for the pages containing the first and last
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* bits, i.e. @start_bit and @start_bit + @cnt - 1, respectively.
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*/
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index = start_bit >> (3 + PAGE_CACHE_SHIFT);
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end_index = (start_bit + cnt - 1) >> (3 + PAGE_CACHE_SHIFT);
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/* Get the page containing the first bit (@start_bit). */
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mapping = vi->i_mapping;
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page = ntfs_map_page(mapping, index);
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if (IS_ERR(page)) {
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if (!is_rollback)
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ntfs_error(vi->i_sb, "Failed to map first page (error "
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"%li), aborting.", PTR_ERR(page));
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return PTR_ERR(page);
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}
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kaddr = page_address(page);
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/* Set @pos to the position of the byte containing @start_bit. */
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pos = (start_bit >> 3) & ~PAGE_CACHE_MASK;
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/* Calculate the position of @start_bit in the first byte. */
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bit = start_bit & 7;
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/* If the first byte is partial, modify the appropriate bits in it. */
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if (bit) {
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u8 *byte = kaddr + pos;
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while ((bit & 7) && cnt) {
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cnt--;
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if (value)
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*byte |= 1 << bit++;
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else
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*byte &= ~(1 << bit++);
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}
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/* If we are done, unmap the page and return success. */
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if (!cnt)
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goto done;
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/* Update @pos to the new position. */
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pos++;
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}
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/*
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* Depending on @value, modify all remaining whole bytes in the page up
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* to @cnt.
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*/
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len = min_t(s64, cnt >> 3, PAGE_CACHE_SIZE - pos);
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memset(kaddr + pos, value ? 0xff : 0, len);
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cnt -= len << 3;
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/* Update @len to point to the first not-done byte in the page. */
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if (cnt < 8)
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len += pos;
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/* If we are not in the last page, deal with all subsequent pages. */
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while (index < end_index) {
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BUG_ON(cnt <= 0);
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/* Update @index and get the next page. */
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flush_dcache_page(page);
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set_page_dirty(page);
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ntfs_unmap_page(page);
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page = ntfs_map_page(mapping, ++index);
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if (IS_ERR(page))
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goto rollback;
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kaddr = page_address(page);
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/*
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* Depending on @value, modify all remaining whole bytes in the
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* page up to @cnt.
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*/
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len = min_t(s64, cnt >> 3, PAGE_CACHE_SIZE);
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memset(kaddr, value ? 0xff : 0, len);
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cnt -= len << 3;
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}
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/*
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* The currently mapped page is the last one. If the last byte is
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* partial, modify the appropriate bits in it. Note, @len is the
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* position of the last byte inside the page.
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*/
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if (cnt) {
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u8 *byte;
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BUG_ON(cnt > 7);
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bit = cnt;
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byte = kaddr + len;
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while (bit--) {
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if (value)
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*byte |= 1 << bit;
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else
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*byte &= ~(1 << bit);
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}
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}
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done:
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/* We are done. Unmap the page and return success. */
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flush_dcache_page(page);
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set_page_dirty(page);
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ntfs_unmap_page(page);
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ntfs_debug("Done.");
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return 0;
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rollback:
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/*
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* Current state:
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* - no pages are mapped
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* - @count - @cnt is the number of bits that have been modified
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*/
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if (is_rollback)
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return PTR_ERR(page);
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if (count != cnt)
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pos = __ntfs_bitmap_set_bits_in_run(vi, start_bit, count - cnt,
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value ? 0 : 1, true);
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else
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pos = 0;
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if (!pos) {
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/* Rollback was successful. */
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ntfs_error(vi->i_sb, "Failed to map subsequent page (error "
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"%li), aborting.", PTR_ERR(page));
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} else {
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/* Rollback failed. */
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ntfs_error(vi->i_sb, "Failed to map subsequent page (error "
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"%li) and rollback failed (error %i). "
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"Aborting and leaving inconsistent metadata. "
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"Unmount and run chkdsk.", PTR_ERR(page), pos);
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NVolSetErrors(NTFS_SB(vi->i_sb));
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}
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return PTR_ERR(page);
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}
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#endif /* NTFS_RW */
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