1 // SPDX-License-Identifier: GPL-2.0-or-later
3  * bitmap.c - NTFS kernel bitmap handling.  Part of the Linux-NTFS project.
5  * Copyright (c) 2004-2005 Anton Altaparmakov
18  * __ntfs_bitmap_set_bits_in_run - set a run of bits in a bitmap to a value
31  * Return 0 on success and -errno on error.
41 	int pos, len;  in __ntfs_bitmap_set_bits_in_run()  local
46 			"value %u.%s", vi->i_ino, (unsigned long long)start_bit,  in __ntfs_bitmap_set_bits_in_run()
54 	 * bits, i.e. @start_bit and @start_bit + @cnt - 1, respectively.  in __ntfs_bitmap_set_bits_in_run()
57 	end_index = (start_bit + cnt - 1) >> (3 + PAGE_SHIFT);  in __ntfs_bitmap_set_bits_in_run()
60 	mapping = vi->i_mapping;  in __ntfs_bitmap_set_bits_in_run()
64 			ntfs_error(vi->i_sb, "Failed to map first page (error "  in __ntfs_bitmap_set_bits_in_run()
70 	/* Set @pos to the position of the byte containing @start_bit. */  in __ntfs_bitmap_set_bits_in_run()
73 	/* Calculate the position of @start_bit in the first byte. */  in __ntfs_bitmap_set_bits_in_run()
76 	/* If the first byte is partial, modify the appropriate bits in it. */  in __ntfs_bitmap_set_bits_in_run()
78 		u8 *byte = kaddr + pos;  in __ntfs_bitmap_set_bits_in_run()  local
80 			cnt--;  in __ntfs_bitmap_set_bits_in_run()
82 				*byte |= 1 << bit++;  in __ntfs_bitmap_set_bits_in_run()
84 				*byte &= ~(1 << bit++);  in __ntfs_bitmap_set_bits_in_run()
97 	len = min_t(s64, cnt >> 3, PAGE_SIZE - pos);  in __ntfs_bitmap_set_bits_in_run()
98 	memset(kaddr + pos, value ? 0xff : 0, len);  in __ntfs_bitmap_set_bits_in_run()
99 	cnt -= len << 3;  in __ntfs_bitmap_set_bits_in_run()
101 	/* Update @len to point to the first not-done byte in the page. */  in __ntfs_bitmap_set_bits_in_run()
103 		len += pos;  in __ntfs_bitmap_set_bits_in_run()
121 		len = min_t(s64, cnt >> 3, PAGE_SIZE);  in __ntfs_bitmap_set_bits_in_run()
122 		memset(kaddr, value ? 0xff : 0, len);  in __ntfs_bitmap_set_bits_in_run()
123 		cnt -= len << 3;  in __ntfs_bitmap_set_bits_in_run()
126 	 * The currently mapped page is the last one.  If the last byte is  in __ntfs_bitmap_set_bits_in_run()
127 	 * partial, modify the appropriate bits in it.  Note, @len is the  in __ntfs_bitmap_set_bits_in_run()
128 	 * position of the last byte inside the page.  in __ntfs_bitmap_set_bits_in_run()
131 		u8 *byte;  in __ntfs_bitmap_set_bits_in_run()  local
136 		byte = kaddr + len;  in __ntfs_bitmap_set_bits_in_run()
137 		while (bit--) {  in __ntfs_bitmap_set_bits_in_run()
139 				*byte |= 1 << bit;  in __ntfs_bitmap_set_bits_in_run()
141 				*byte &= ~(1 << bit);  in __ntfs_bitmap_set_bits_in_run()
154 	 *	- no pages are mapped  in __ntfs_bitmap_set_bits_in_run()
155 	 *	- @count - @cnt is the number of bits that have been modified  in __ntfs_bitmap_set_bits_in_run()
160 		pos = __ntfs_bitmap_set_bits_in_run(vi, start_bit, count - cnt,  in __ntfs_bitmap_set_bits_in_run()
166 		ntfs_error(vi->i_sb, "Failed to map subsequent page (error "  in __ntfs_bitmap_set_bits_in_run()
170 		ntfs_error(vi->i_sb, "Failed to map subsequent page (error "  in __ntfs_bitmap_set_bits_in_run()
174 		NVolSetErrors(NTFS_SB(vi->i_sb));  in __ntfs_bitmap_set_bits_in_run()