alloc.c revision 31dbecd482405e0d3a67eb58e1a1c8cb9f2ad83e 
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#if EXT2_FLAT_INCLUDES
27#include "ext2_fs.h"
28#else
29#include <linux/ext2_fs.h>
30#endif
31
32#include "ext2fs.h"
33
34/*
35 * Right now, just search forward from the parent directory's block
36 * group to find the next free inode.
37 *
38 * Should have a special policy for directories.
39 */
40errcode_t ext2fs_new_inode(ext2_filsys fs, ext2_ino_t dir, int mode,
41			   ext2fs_inode_bitmap map, ext2_ino_t *ret)
42{
43	ext2_ino_t	dir_group = 0;
44	ext2_ino_t	i;
45	ext2_ino_t	start_inode;
46
47	EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
48
49	if (!map)
50		map = fs->inode_map;
51	if (!map)
52		return EXT2_ET_NO_INODE_BITMAP;
53
54	if (dir > 0)
55		dir_group = (dir - 1) / EXT2_INODES_PER_GROUP(fs->super);
56
57	start_inode = (dir_group * EXT2_INODES_PER_GROUP(fs->super)) + 1;
58	if (start_inode < EXT2_FIRST_INODE(fs->super))
59		start_inode = EXT2_FIRST_INODE(fs->super);
60	i = start_inode;
61
62	do {
63		if (!ext2fs_test_inode_bitmap(map, i))
64			break;
65		i++;
66		if (i > fs->super->s_inodes_count)
67			i = EXT2_FIRST_INODE(fs->super);
68	} while (i != start_inode);
69
70	if (ext2fs_test_inode_bitmap(map, i))
71		return EXT2_ET_INODE_ALLOC_FAIL;
72	*ret = i;
73	return 0;
74}
75
76/*
77 * Stupid algorithm --- we now just search forward starting from the
78 * goal.  Should put in a smarter one someday....
79 */
80errcode_t ext2fs_new_block(ext2_filsys fs, blk_t goal,
81			   ext2fs_block_bitmap map, blk_t *ret)
82{
83	blk_t	i;
84
85	EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
86
87	if (!map)
88		map = fs->block_map;
89	if (!map)
90		return EXT2_ET_NO_BLOCK_BITMAP;
91	if (!goal || (goal >= fs->super->s_blocks_count))
92		goal = fs->super->s_first_data_block;
93	i = goal;
94	do {
95		if (!ext2fs_test_block_bitmap(map, i)) {
96			*ret = i;
97			return 0;
98		}
99		i++;
100		if (i >= fs->super->s_blocks_count)
101			i = fs->super->s_first_data_block;
102	} while (i != goal);
103	return EXT2_ET_BLOCK_ALLOC_FAIL;
104}
105
106/*
107 * This function zeros out the allocated block, and updates all of the
108 * appropriate filesystem records.
109 */
110errcode_t ext2fs_alloc_block(ext2_filsys fs, blk_t goal,
111			     char *block_buf, blk_t *ret)
112{
113	errcode_t	retval;
114	blk_t		block;
115	int		group;
116	char		*buf = 0;
117
118	if (!block_buf) {
119		retval = ext2fs_get_mem(fs->blocksize, (void **) &buf);
120		if (retval)
121			return retval;
122		block_buf = buf;
123	}
124	memset(block_buf, 0, fs->blocksize);
125
126	if (!fs->block_map) {
127		retval = ext2fs_read_block_bitmap(fs);
128		if (retval)
129			goto fail;
130	}
131
132	retval = ext2fs_new_block(fs, goal, 0, &block);
133	if (retval)
134		goto fail;
135
136	retval = io_channel_write_blk(fs->io, block, 1, block_buf);
137	if (retval)
138		goto fail;
139
140	fs->super->s_free_blocks_count--;
141	group = ext2fs_group_of_blk(fs, block);
142	fs->group_desc[group].bg_free_blocks_count--;
143	ext2fs_mark_block_bitmap(fs->block_map, block);
144	ext2fs_mark_super_dirty(fs);
145	ext2fs_mark_bb_dirty(fs);
146	*ret = block;
147	return 0;
148
149fail:
150	if (buf)
151		ext2fs_free_mem((void **) &buf);
152	return retval;
153}
154
155errcode_t ext2fs_get_free_blocks(ext2_filsys fs, blk_t start, blk_t finish,
156				 int num, ext2fs_block_bitmap map, blk_t *ret)
157{
158	blk_t	b = start;
159
160	EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
161
162	if (!map)
163		map = fs->block_map;
164	if (!map)
165		return EXT2_ET_NO_BLOCK_BITMAP;
166	if (!b)
167		b = fs->super->s_first_data_block;
168	if (!finish)
169		finish = start;
170	if (!num)
171		num = 1;
172	do {
173		if (b+num-1 > fs->super->s_blocks_count)
174			b = fs->super->s_first_data_block;
175		if (ext2fs_fast_test_block_bitmap_range(map, b, num)) {
176			*ret = b;
177			return 0;
178		}
179		b++;
180	} while (b != finish);
181	return EXT2_ET_BLOCK_ALLOC_FAIL;
182}
183
184