alloc.c revision efc6f628e15de95bcd13e4f0ee223cb42115d520 
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 "ext2_fs.h"
27#include "ext2fs.h"
28
29/*
30 * Check for uninit block bitmaps and deal with them appropriately
31 */
32static check_block_uninit(ext2_filsys fs, ext2fs_block_bitmap map,
33			  dgrp_t group)
34{
35	int		i;
36	blk_t		blk, super_blk, old_desc_blk, new_desc_blk;
37	int		old_desc_blocks;
38
39	if (!(EXT2_HAS_RO_COMPAT_FEATURE(fs->super,
40					 EXT4_FEATURE_RO_COMPAT_GDT_CSUM)) ||
41	    !(fs->group_desc[group].bg_flags & EXT2_BG_BLOCK_UNINIT))
42		return;
43
44	blk = (group * fs->super->s_blocks_per_group) +
45		fs->super->s_first_data_block;
46
47	ext2fs_super_and_bgd_loc(fs, group, &super_blk,
48				 &old_desc_blk, &new_desc_blk, 0);
49
50	if (fs->super->s_feature_incompat &
51	    EXT2_FEATURE_INCOMPAT_META_BG)
52		old_desc_blocks = fs->super->s_first_meta_bg;
53	else
54		old_desc_blocks = fs->desc_blocks + fs->super->s_reserved_gdt_blocks;
55
56	for (i=0; i < fs->super->s_blocks_per_group; i++, blk++) {
57		if ((blk == super_blk) ||
58		    (old_desc_blk && old_desc_blocks &&
59		     (blk >= old_desc_blk) &&
60		     (blk < old_desc_blk + old_desc_blocks)) ||
61		    (new_desc_blk && (blk == new_desc_blk)) ||
62		    (blk == fs->group_desc[group].bg_block_bitmap) ||
63		    (blk == fs->group_desc[group].bg_inode_bitmap) ||
64		    (blk >= fs->group_desc[group].bg_inode_table &&
65		     (blk < fs->group_desc[group].bg_inode_table
66		      + fs->inode_blocks_per_group)))
67			ext2fs_fast_mark_block_bitmap(map, blk);
68		else
69			ext2fs_fast_unmark_block_bitmap(map, blk);
70	}
71	fs->group_desc[group].bg_flags &= ~EXT2_BG_BLOCK_UNINIT;
72	ext2fs_group_desc_csum_set(fs, group);
73}
74
75/*
76 * Check for uninit inode bitmaps and deal with them appropriately
77 */
78static check_inode_uninit(ext2_filsys fs, ext2fs_inode_bitmap map,
79			  dgrp_t group)
80{
81	int		i;
82	ext2_ino_t	ino;
83
84	if (!(EXT2_HAS_RO_COMPAT_FEATURE(fs->super,
85					 EXT4_FEATURE_RO_COMPAT_GDT_CSUM)) ||
86	    !(fs->group_desc[group].bg_flags & EXT2_BG_INODE_UNINIT))
87		return;
88
89	ino = (group * fs->super->s_inodes_per_group) + 1;
90	for (i=0; i < fs->super->s_inodes_per_group; i++, ino++)
91		ext2fs_fast_unmark_inode_bitmap(map, ino);
92
93	fs->group_desc[group].bg_flags &= ~EXT2_BG_INODE_UNINIT;
94	check_block_uninit(fs, fs->block_map, group);
95}
96
97/*
98 * Right now, just search forward from the parent directory's block
99 * group to find the next free inode.
100 *
101 * Should have a special policy for directories.
102 */
103errcode_t ext2fs_new_inode(ext2_filsys fs, ext2_ino_t dir,
104			   int mode EXT2FS_ATTR((unused)),
105			   ext2fs_inode_bitmap map, ext2_ino_t *ret)
106{
107	ext2_ino_t	dir_group = 0;
108	ext2_ino_t	i;
109	ext2_ino_t	start_inode;
110
111	EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
112
113	if (!map)
114		map = fs->inode_map;
115	if (!map)
116		return EXT2_ET_NO_INODE_BITMAP;
117
118	if (dir > 0)
119		dir_group = (dir - 1) / EXT2_INODES_PER_GROUP(fs->super);
120
121	start_inode = (dir_group * EXT2_INODES_PER_GROUP(fs->super)) + 1;
122	if (start_inode < EXT2_FIRST_INODE(fs->super))
123		start_inode = EXT2_FIRST_INODE(fs->super);
124	i = start_inode;
125
126	do {
127		if (((i - 1) % EXT2_INODES_PER_GROUP(fs->super)) == 0)
128			check_inode_uninit(fs, map, (i - 1) /
129					   EXT2_INODES_PER_GROUP(fs->super));
130
131		if (!ext2fs_fast_test_inode_bitmap(map, i))
132			break;
133		i++;
134		if (i > fs->super->s_inodes_count)
135			i = EXT2_FIRST_INODE(fs->super);
136	} while (i != start_inode);
137
138	if (ext2fs_test_inode_bitmap(map, i))
139		return EXT2_ET_INODE_ALLOC_FAIL;
140	*ret = i;
141	return 0;
142}
143
144/*
145 * Stupid algorithm --- we now just search forward starting from the
146 * goal.  Should put in a smarter one someday....
147 */
148errcode_t ext2fs_new_block(ext2_filsys fs, blk_t goal,
149			   ext2fs_block_bitmap map, blk_t *ret)
150{
151	blk_t	i;
152
153	EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
154
155	if (!map)
156		map = fs->block_map;
157	if (!map)
158		return EXT2_ET_NO_BLOCK_BITMAP;
159	if (!goal || (goal >= fs->super->s_blocks_count))
160		goal = fs->super->s_first_data_block;
161	i = goal;
162	check_block_uninit(fs, map,
163			   (i - fs->super->s_first_data_block) /
164			   EXT2_BLOCKS_PER_GROUP(fs->super));
165	do {
166		if (((i - fs->super->s_first_data_block) %
167		     EXT2_BLOCKS_PER_GROUP(fs->super)) == 0)
168			check_block_uninit(fs, map,
169					   (i - fs->super->s_first_data_block) /
170					   EXT2_BLOCKS_PER_GROUP(fs->super));
171
172		if (!ext2fs_fast_test_block_bitmap(map, i)) {
173			*ret = i;
174			return 0;
175		}
176		i++;
177		if (i >= fs->super->s_blocks_count)
178			i = fs->super->s_first_data_block;
179	} while (i != goal);
180	return EXT2_ET_BLOCK_ALLOC_FAIL;
181}
182
183/*
184 * This function zeros out the allocated block, and updates all of the
185 * appropriate filesystem records.
186 */
187errcode_t ext2fs_alloc_block(ext2_filsys fs, blk_t goal,
188			     char *block_buf, blk_t *ret)
189{
190	errcode_t	retval;
191	blk_t		block;
192	char		*buf = 0;
193
194	if (!block_buf) {
195		retval = ext2fs_get_mem(fs->blocksize, &buf);
196		if (retval)
197			return retval;
198		block_buf = buf;
199	}
200	memset(block_buf, 0, fs->blocksize);
201
202	if (fs->get_alloc_block) {
203		blk64_t	new;
204
205		retval = (fs->get_alloc_block)(fs, (blk64_t) goal, &new);
206		if (retval)
207			goto fail;
208		block = (blk_t) new;
209	} else {
210		if (!fs->block_map) {
211			retval = ext2fs_read_block_bitmap(fs);
212			if (retval)
213				goto fail;
214		}
215
216		retval = ext2fs_new_block(fs, goal, 0, &block);
217		if (retval)
218			goto fail;
219	}
220
221	retval = io_channel_write_blk(fs->io, block, 1, block_buf);
222	if (retval)
223		goto fail;
224
225	ext2fs_block_alloc_stats(fs, block, +1);
226	*ret = block;
227
228fail:
229	if (buf)
230		ext2fs_free_mem(&buf);
231	return retval;
232}
233
234errcode_t ext2fs_get_free_blocks(ext2_filsys fs, blk_t start, blk_t finish,
235				 int num, ext2fs_block_bitmap map, blk_t *ret)
236{
237	blk_t	b = start;
238
239	EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
240
241	if (!map)
242		map = fs->block_map;
243	if (!map)
244		return EXT2_ET_NO_BLOCK_BITMAP;
245	if (!b)
246		b = fs->super->s_first_data_block;
247	if (!finish)
248		finish = start;
249	if (!num)
250		num = 1;
251	do {
252		if (b+num-1 > fs->super->s_blocks_count)
253			b = fs->super->s_first_data_block;
254		if (ext2fs_fast_test_block_bitmap_range(map, b, num)) {
255			*ret = b;
256			return 0;
257		}
258		b++;
259	} while (b != finish);
260	return EXT2_ET_BLOCK_ALLOC_FAIL;
261}
262
263void ext2fs_set_alloc_block_callback(ext2_filsys fs,
264				     errcode_t (*func)(ext2_filsys fs,
265						       blk64_t goal,
266						       blk64_t *ret),
267				     errcode_t (**old)(ext2_filsys fs,
268						       blk64_t goal,
269						       blk64_t *ret))
270{
271	if (!fs || fs->magic != EXT2_ET_MAGIC_EXT2FS_FILSYS)
272		return;
273
274	if (old)
275		*old = fs->get_alloc_block;
276
277	fs->get_alloc_block = func;
278}
279