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