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fs/ntfs/bitmap.c
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/* * bitmap.c - NTFS kernel bitmap handling. Part of the Linux-NTFS project. * |
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* Copyright (c) 2004-2005 Anton Altaparmakov |
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* * 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) |
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* @is_rollback: if 'true' this is a rollback operation |
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* * 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. * |
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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. * * Return 0 on success and -errno on error. */ 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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{ 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; |
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while ((bit & 7) && cnt) { cnt--; |
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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, |
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value ? 0 : 1, true); |
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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 */ |