alloc.c revision 5be8dc2143c7b3b21a9b8fb56797dd855ee87560 
1/*
2 * alloc.c --- allocate new inodes, blocks for ext2fs
3 *
4 * Copyright (C) 1993, 1994, 1995, 1996 Theodore Ts'o.
5 *
6 * %Begin-Header%
7 * This file may be redistributed under the terms of the GNU Public
8 * License.
9 * %End-Header%
10 *
11 */
12
13#include <stdio.h>
14#if HAVE_UNISTD_H
15#include <unistd.h>
16#endif
17#include <time.h>
18#include <string.h>
19#if HAVE_SYS_STAT_H
20#include <sys/stat.h>
21#endif
22#if HAVE_SYS_TYPES_H
23#include <sys/types.h>
24#endif
25
26#include <linux/ext2_fs.h>
27
28#include "ext2fs.h"
29
30/*
31 * Right now, just search forward from the parent directory's block
32 * group to find the next free inode.
33 *
34 * Should have a special policy for directories.
35 */
36errcode_t ext2fs_new_inode(ext2_filsys fs, ino_t dir, int mode,
37			   ext2fs_inode_bitmap map, ino_t *ret)
38{
39	ino_t	dir_group = 0;
40	ino_t	i;
41	ino_t	start_inode;
42
43	EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
44
45	if (!map)
46		map = fs->inode_map;
47	if (!map)
48		return EXT2_ET_NO_INODE_BITMAP;
49
50	if (dir > 0)
51		dir_group = (dir - 1) / EXT2_INODES_PER_GROUP(fs->super);
52
53	start_inode = (dir_group * EXT2_INODES_PER_GROUP(fs->super)) + 1;
54	if (start_inode < EXT2_FIRST_INODE(fs->super))
55		start_inode = EXT2_FIRST_INODE(fs->super);
56	i = start_inode;
57
58	do {
59		if (!ext2fs_test_inode_bitmap(map, i))
60			break;
61		i++;
62		if (i > fs->super->s_inodes_count)
63			i = EXT2_FIRST_INODE(fs->super);
64	} while (i != start_inode);
65
66	if (ext2fs_test_inode_bitmap(map, i))
67		return EXT2_ET_INODE_ALLOC_FAIL;
68	*ret = i;
69	return 0;
70}
71
72/*
73 * Stupid algorithm --- we now just search forward starting from the
74 * goal.  Should put in a smarter one someday....
75 */
76errcode_t ext2fs_new_block(ext2_filsys fs, blk_t goal,
77			   ext2fs_block_bitmap map, blk_t *ret)
78{
79	blk_t	i;
80
81	EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
82
83	if (!map)
84		map = fs->block_map;
85	if (!map)
86		return EXT2_ET_NO_BLOCK_BITMAP;
87	if (!goal || (goal >= fs->super->s_blocks_count))
88		goal = fs->super->s_first_data_block;
89	i = goal;
90	do {
91		if (!ext2fs_test_block_bitmap(map, i)) {
92			*ret = i;
93			return 0;
94		}
95		i++;
96		if (i >= fs->super->s_blocks_count)
97			i = fs->super->s_first_data_block;
98	} while (i != goal);
99	return EXT2_ET_BLOCK_ALLOC_FAIL;
100}
101
102/*
103 * This function zeros out the allocated block, and updates all of the
104 * appropriate filesystem records.
105 */
106errcode_t ext2fs_alloc_block(ext2_filsys fs, blk_t goal,
107			     char *block_buf, blk_t *ret)
108{
109	errcode_t	retval;
110	blk_t		block;
111	int		group;
112	char		*buf = 0;
113
114	if (!block_buf) {
115		retval = ext2fs_get_mem(fs->blocksize, (void **) &buf);
116		if (retval)
117			return retval;
118		block_buf = buf;
119	}
120	memset(block_buf, 0, fs->blocksize);
121
122	if (!fs->block_map) {
123		retval = ext2fs_read_block_bitmap(fs);
124		if (retval)
125			goto fail;
126	}
127
128	retval = ext2fs_new_block(fs, goal, 0, &block);
129	if (retval)
130		goto fail;
131
132	retval = io_channel_write_blk(fs->io, block, 1, block_buf);
133	if (retval)
134		goto fail;
135
136	fs->super->s_free_blocks_count--;
137	group = ext2fs_group_of_blk(fs, block);
138	fs->group_desc[group].bg_free_blocks_count--;
139	ext2fs_mark_block_bitmap(fs->block_map, block);
140	ext2fs_mark_super_dirty(fs);
141	ext2fs_mark_bb_dirty(fs);
142	*ret = block;
143	return 0;
144
145fail:
146	if (buf)
147		ext2fs_free_mem((void **) &buf);
148	return retval;
149}
150
151errcode_t ext2fs_get_free_blocks(ext2_filsys fs, blk_t start, blk_t finish,
152				 int num, ext2fs_block_bitmap map, blk_t *ret)
153{
154	blk_t	b = start;
155
156	EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
157
158	if (!map)
159		map = fs->block_map;
160	if (!map)
161		return EXT2_ET_NO_BLOCK_BITMAP;
162	if (!b)
163		b = fs->super->s_first_data_block;
164	if (!finish)
165		finish = start;
166	if (!num)
167		num = 1;
168	do {
169		if (b+num-1 > fs->super->s_blocks_count)
170			b = fs->super->s_first_data_block;
171		if (ext2fs_fast_test_block_bitmap_range(map, b, num)) {
172			*ret = b;
173			return 0;
174		}
175		b++;
176	} while (b != finish);
177	return EXT2_ET_BLOCK_ALLOC_FAIL;
178}
179
180