--- /dev/null
+/*
+ * bitmap.c - NTFS kernel bitmap handling. Part of the Linux-NTFS project.
+ *
+ * Copyright (c) 2004 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 "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--) {
+ 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 */
git://git.onelab.eu / linux-2.6.git / blobdiff