summaryrefslogtreecommitdiff
path: root/e2fsprogs/ext2fs/bmap.c
blob: b22fe3dbf66583b99006d37bb4d889ade2454651 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
/* vi: set sw=4 ts=4: */
/*
 * bmap.c --- logical to physical block mapping
 *
 * Copyright (C) 1997 Theodore Ts'o.
 *
 * %Begin-Header%
 * This file may be redistributed under the terms of the GNU Public
 * License.
 * %End-Header%
 */

#include <stdio.h>
#include <string.h>
#if HAVE_UNISTD_H
#include <unistd.h>
#endif

#include "ext2_fs.h"
#include "ext2fs.h"

extern errcode_t ext2fs_bmap(ext2_filsys fs, ext2_ino_t ino,
			     struct ext2_inode *inode,
			     char *block_buf, int bmap_flags,
			     blk_t block, blk_t *phys_blk);

#define inode_bmap(inode, nr) ((inode)->i_block[(nr)])

static errcode_t block_ind_bmap(ext2_filsys fs, int flags,
					      blk_t ind, char *block_buf,
					      int *blocks_alloc,
					      blk_t nr, blk_t *ret_blk)
{
	errcode_t	retval;
	blk_t		b;

	if (!ind) {
		if (flags & BMAP_SET)
			return EXT2_ET_SET_BMAP_NO_IND;
		*ret_blk = 0;
		return 0;
	}
	retval = io_channel_read_blk(fs->io, ind, 1, block_buf);
	if (retval)
		return retval;

	if (flags & BMAP_SET) {
		b = *ret_blk;
#if BB_BIG_ENDIAN
		if ((fs->flags & EXT2_FLAG_SWAP_BYTES) ||
		    (fs->flags & EXT2_FLAG_SWAP_BYTES_WRITE))
			b = ext2fs_swab32(b);
#endif
		((blk_t *) block_buf)[nr] = b;
		return io_channel_write_blk(fs->io, ind, 1, block_buf);
	}

	b = ((blk_t *) block_buf)[nr];

#if BB_BIG_ENDIAN
	if ((fs->flags & EXT2_FLAG_SWAP_BYTES) ||
	    (fs->flags & EXT2_FLAG_SWAP_BYTES_READ))
		b = ext2fs_swab32(b);
#endif

	if (!b && (flags & BMAP_ALLOC)) {
		b = nr ? ((blk_t *) block_buf)[nr-1] : 0;
		retval = ext2fs_alloc_block(fs, b,
					    block_buf + fs->blocksize, &b);
		if (retval)
			return retval;

#if BB_BIG_ENDIAN
		if ((fs->flags & EXT2_FLAG_SWAP_BYTES) ||
		    (fs->flags & EXT2_FLAG_SWAP_BYTES_WRITE))
			((blk_t *) block_buf)[nr] = ext2fs_swab32(b);
		else
#endif
			((blk_t *) block_buf)[nr] = b;

		retval = io_channel_write_blk(fs->io, ind, 1, block_buf);
		if (retval)
			return retval;

		(*blocks_alloc)++;
	}

	*ret_blk = b;
	return 0;
}

static errcode_t block_dind_bmap(ext2_filsys fs, int flags,
					       blk_t dind, char *block_buf,
					       int *blocks_alloc,
					       blk_t nr, blk_t *ret_blk)
{
	blk_t		b;
	errcode_t	retval;
	blk_t		addr_per_block;

	addr_per_block = (blk_t) fs->blocksize >> 2;

	retval = block_ind_bmap(fs, flags & ~BMAP_SET, dind, block_buf,
				blocks_alloc, nr / addr_per_block, &b);
	if (retval)
		return retval;
	retval = block_ind_bmap(fs, flags, b, block_buf, blocks_alloc,
				nr % addr_per_block, ret_blk);
	return retval;
}

static errcode_t block_tind_bmap(ext2_filsys fs, int flags,
					       blk_t tind, char *block_buf,
					       int *blocks_alloc,
					       blk_t nr, blk_t *ret_blk)
{
	blk_t		b;
	errcode_t	retval;
	blk_t		addr_per_block;

	addr_per_block = (blk_t) fs->blocksize >> 2;

	retval = block_dind_bmap(fs, flags & ~BMAP_SET, tind, block_buf,
				 blocks_alloc, nr / addr_per_block, &b);
	if (retval)
		return retval;
	retval = block_ind_bmap(fs, flags, b, block_buf, blocks_alloc,
				nr % addr_per_block, ret_blk);
	return retval;
}

errcode_t ext2fs_bmap(ext2_filsys fs, ext2_ino_t ino, struct ext2_inode *inode,
		      char *block_buf, int bmap_flags, blk_t block,
		      blk_t *phys_blk)
{
	struct ext2_inode inode_buf;
	blk_t addr_per_block;
	blk_t	b;
	char	*buf = 0;
	errcode_t	retval = 0;
	int		blocks_alloc = 0, inode_dirty = 0;

	if (!(bmap_flags & BMAP_SET))
		*phys_blk = 0;

	/* Read inode structure if necessary */
	if (!inode) {
		retval = ext2fs_read_inode(fs, ino, &inode_buf);
		if (retval)
			return retval;
		inode = &inode_buf;
	}
	addr_per_block = (blk_t) fs->blocksize >> 2;

	if (!block_buf) {
		retval = ext2fs_get_mem(fs->blocksize * 2, &buf);
		if (retval)
			return retval;
		block_buf = buf;
	}

	if (block < EXT2_NDIR_BLOCKS) {
		if (bmap_flags & BMAP_SET) {
			b = *phys_blk;
#if BB_BIG_ENDIAN
			if ((fs->flags & EXT2_FLAG_SWAP_BYTES) ||
			    (fs->flags & EXT2_FLAG_SWAP_BYTES_READ))
				b = ext2fs_swab32(b);
#endif
			inode_bmap(inode, block) = b;
			inode_dirty++;
			goto done;
		}

		*phys_blk = inode_bmap(inode, block);
		b = block ? inode_bmap(inode, block-1) : 0;

		if ((*phys_blk == 0) && (bmap_flags & BMAP_ALLOC)) {
			retval = ext2fs_alloc_block(fs, b, block_buf, &b);
			if (retval)
				goto done;
			inode_bmap(inode, block) = b;
			blocks_alloc++;
			*phys_blk = b;
		}
		goto done;
	}

	/* Indirect block */
	block -= EXT2_NDIR_BLOCKS;
	if (block < addr_per_block) {
		b = inode_bmap(inode, EXT2_IND_BLOCK);
		if (!b) {
			if (!(bmap_flags & BMAP_ALLOC)) {
				if (bmap_flags & BMAP_SET)
					retval = EXT2_ET_SET_BMAP_NO_IND;
				goto done;
			}

			b = inode_bmap(inode, EXT2_IND_BLOCK-1);
			retval = ext2fs_alloc_block(fs, b, block_buf, &b);
			if (retval)
				goto done;
			inode_bmap(inode, EXT2_IND_BLOCK) = b;
			blocks_alloc++;
		}
		retval = block_ind_bmap(fs, bmap_flags, b, block_buf,
					&blocks_alloc, block, phys_blk);
		goto done;
	}

	/* Doubly indirect block  */
	block -= addr_per_block;
	if (block < addr_per_block * addr_per_block) {
		b = inode_bmap(inode, EXT2_DIND_BLOCK);
		if (!b) {
			if (!(bmap_flags & BMAP_ALLOC)) {
				if (bmap_flags & BMAP_SET)
					retval = EXT2_ET_SET_BMAP_NO_IND;
				goto done;
			}

			b = inode_bmap(inode, EXT2_IND_BLOCK);
			retval = ext2fs_alloc_block(fs, b, block_buf, &b);
			if (retval)
				goto done;
			inode_bmap(inode, EXT2_DIND_BLOCK) = b;
			blocks_alloc++;
		}
		retval = block_dind_bmap(fs, bmap_flags, b, block_buf,
					 &blocks_alloc, block, phys_blk);
		goto done;
	}

	/* Triply indirect block */
	block -= addr_per_block * addr_per_block;
	b = inode_bmap(inode, EXT2_TIND_BLOCK);
	if (!b) {
		if (!(bmap_flags & BMAP_ALLOC)) {
			if (bmap_flags & BMAP_SET)
				retval = EXT2_ET_SET_BMAP_NO_IND;
			goto done;
		}

		b = inode_bmap(inode, EXT2_DIND_BLOCK);
		retval = ext2fs_alloc_block(fs, b, block_buf, &b);
		if (retval)
			goto done;
		inode_bmap(inode, EXT2_TIND_BLOCK) = b;
		blocks_alloc++;
	}
	retval = block_tind_bmap(fs, bmap_flags, b, block_buf,
				 &blocks_alloc, block, phys_blk);
done:
	ext2fs_free_mem(&buf);
	if ((retval == 0) && (blocks_alloc || inode_dirty)) {
		inode->i_blocks += (blocks_alloc * fs->blocksize) / 512;
		retval = ext2fs_write_inode(fs, ino, inode);
	}
	return retval;
}