alloc.c revision 543547a52a20cb7e69d74921b2f691078fd55d83 
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 Library
8 * General Public License, version 2.
9 * %End-Header%
10 */
11
12#include <stdio.h>
13#if HAVE_UNISTD_H
14#include <unistd.h>
15#endif
16#include <time.h>
17#include <string.h>
18#if HAVE_SYS_STAT_H
19#include <sys/stat.h>
20#endif
21#if HAVE_SYS_TYPES_H
22#include <sys/types.h>
23#endif
24
25#include "ext2_fs.h"
26#include "ext2fs.h"
27
28/*
29 * Check for uninit block bitmaps and deal with them appropriately
30 */
31static void check_block_uninit(ext2_filsys fs, ext2fs_block_bitmap map,
32			  dgrp_t group)
33{
34	blk_t		i;
35	blk_t		blk, super_blk, old_desc_blk, new_desc_blk;
36	int		old_desc_blocks;
37
38	if (!(EXT2_HAS_RO_COMPAT_FEATURE(fs->super,
39					 EXT4_FEATURE_RO_COMPAT_GDT_CSUM)) ||
40	    !(fs->group_desc[group].bg_flags & EXT2_BG_BLOCK_UNINIT))
41		return;
42
43	blk = (group * fs->super->s_blocks_per_group) +
44		fs->super->s_first_data_block;
45
46	ext2fs_super_and_bgd_loc(fs, group, &super_blk,
47				 &old_desc_blk, &new_desc_blk, 0);
48
49	if (fs->super->s_feature_incompat &
50	    EXT2_FEATURE_INCOMPAT_META_BG)
51		old_desc_blocks = fs->super->s_first_meta_bg;
52	else
53		old_desc_blocks = fs->desc_blocks + fs->super->s_reserved_gdt_blocks;
54
55	for (i=0; i < fs->super->s_blocks_per_group; i++, blk++) {
56		if ((blk == super_blk) ||
57		    (old_desc_blk && old_desc_blocks &&
58		     (blk >= old_desc_blk) &&
59		     (blk < old_desc_blk + old_desc_blocks)) ||
60		    (new_desc_blk && (blk == new_desc_blk)) ||
61		    (blk == fs->group_desc[group].bg_block_bitmap) ||
62		    (blk == fs->group_desc[group].bg_inode_bitmap) ||
63		    (blk >= fs->group_desc[group].bg_inode_table &&
64		     (blk < fs->group_desc[group].bg_inode_table
65		      + fs->inode_blocks_per_group)))
66			ext2fs_fast_mark_block_bitmap(map, blk);
67		else
68			ext2fs_fast_unmark_block_bitmap(map, blk);
69	}
70	fs->group_desc[group].bg_flags &= ~EXT2_BG_BLOCK_UNINIT;
71	ext2fs_group_desc_csum_set(fs, group);
72}
73
74/*
75 * Check for uninit inode bitmaps and deal with them appropriately
76 */
77static void check_inode_uninit(ext2_filsys fs, ext2fs_inode_bitmap map,
78			  dgrp_t group)
79{
80	ext2_ino_t	i, ino;
81
82	if (!(EXT2_HAS_RO_COMPAT_FEATURE(fs->super,
83					 EXT4_FEATURE_RO_COMPAT_GDT_CSUM)) ||
84	    !(fs->group_desc[group].bg_flags & EXT2_BG_INODE_UNINIT))
85		return;
86
87	ino = (group * fs->super->s_inodes_per_group) + 1;
88	for (i=0; i < fs->super->s_inodes_per_group; i++, ino++)
89		ext2fs_fast_unmark_inode_bitmap(map, ino);
90
91	fs->group_desc[group].bg_flags &= ~EXT2_BG_INODE_UNINIT;
92	check_block_uninit(fs, fs->block_map, group);
93}
94
95/*
96 * Right now, just search forward from the parent directory's block
97 * group to find the next free inode.
98 *
99 * Should have a special policy for directories.
100 */
101errcode_t ext2fs_new_inode(ext2_filsys fs, ext2_ino_t dir,
102			   int mode EXT2FS_ATTR((unused)),
103			   ext2fs_inode_bitmap map, ext2_ino_t *ret)
104{
105	ext2_ino_t	dir_group = 0;
106	ext2_ino_t	i;
107	ext2_ino_t	start_inode;
108
109	EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
110
111	if (!map)
112		map = fs->inode_map;
113	if (!map)
114		return EXT2_ET_NO_INODE_BITMAP;
115
116	if (dir > 0)
117		dir_group = (dir - 1) / EXT2_INODES_PER_GROUP(fs->super);
118
119	start_inode = (dir_group * EXT2_INODES_PER_GROUP(fs->super)) + 1;
120	if (start_inode < EXT2_FIRST_INODE(fs->super))
121		start_inode = EXT2_FIRST_INODE(fs->super);
122	if (start_inode > fs->super->s_inodes_count)
123		return EXT2_ET_INODE_ALLOC_FAIL;
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