/* * 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_CACHE_SHIFT);	end_index = (start_bit + cnt - 1) >> (3 + PAGE_CACHE_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_CACHE_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_CACHE_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_CACHE_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 */