aboutsummaryrefslogtreecommitdiffstats
path: root/lib/ext2fs/closefs.c
blob: 659ee27f03676ae85d32922e165ca4038b623bf2 (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
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
/*
 * closefs.c --- close an ext2 filesystem
 * 
 * Copyright (C) 1993, 1994, 1995, 1996 Theodore Ts'o.
 *
 * %Begin-Header%
 * This file may be redistributed under the terms of the GNU Public
 * License.
 * %End-Header%
 */

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

#include "ext2_fs.h"
#include "ext2fsP.h"

static int test_root(int a, int b)
{
	if (a == 0)
		return 1;
	while (1) {
		if (a == 1)
			return 1;
		if (a % b)
			return 0;
		a = a / b;
	}
}

int ext2fs_bg_has_super(ext2_filsys fs, int group_block)
{
	if (!(fs->super->s_feature_ro_compat &
	      EXT2_FEATURE_RO_COMPAT_SPARSE_SUPER))
		return 1;

	if (test_root(group_block, 3) || (test_root(group_block, 5)) ||
	    test_root(group_block, 7))
		return 1;

	return 0;
}

int ext2fs_super_and_bgd_loc(ext2_filsys fs, 
			     dgrp_t group,
			     blk_t *ret_super_blk,
			     blk_t *ret_old_desc_blk,
			     blk_t *ret_new_desc_blk,
			     int *ret_meta_bg)
{
	blk_t	group_block, super_blk = 0, old_desc_blk = 0, new_desc_blk = 0;
	unsigned int meta_bg, meta_bg_size;
	int	numblocks, has_super;
	int	old_desc_blocks;

	group_block = fs->super->s_first_data_block +
		(group * fs->super->s_blocks_per_group);

	if (fs->super->s_feature_incompat & EXT2_FEATURE_INCOMPAT_META_BG)
		old_desc_blocks = fs->super->s_first_meta_bg;
	else
		old_desc_blocks = 
			fs->desc_blocks + fs->super->s_reserved_gdt_blocks;

	if (group == fs->group_desc_count-1) {
		numblocks = (fs->super->s_blocks_count -
			     fs->super->s_first_data_block) %
			fs->super->s_blocks_per_group;
		if (!numblocks)
			numblocks = fs->super->s_blocks_per_group;
	} else
		numblocks = fs->super->s_blocks_per_group;

	has_super = ext2fs_bg_has_super(fs, group);

	if (has_super) {
		super_blk = group_block;
		numblocks--;
	}
	meta_bg_size = (fs->blocksize / sizeof (struct ext2_group_desc));
	meta_bg = group / meta_bg_size;

	if (!(fs->super->s_feature_incompat & EXT2_FEATURE_INCOMPAT_META_BG) ||
	    (meta_bg < fs->super->s_first_meta_bg)) {
		if (has_super) {
			old_desc_blk = group_block + 1;
			numblocks -= old_desc_blocks;
		}
	} else {
		if (((group % meta_bg_size) == 0) ||
		    ((group % meta_bg_size) == 1) ||
		    ((group % meta_bg_size) == (meta_bg_size-1))) {
			if (has_super)
				has_super = 1;
			new_desc_blk = group_block + has_super;
			numblocks--;
		}
	}
		
	numblocks -= 2 + fs->inode_blocks_per_group;

	if (ret_super_blk)
		*ret_super_blk = super_blk;
	if (ret_old_desc_blk)
		*ret_old_desc_blk = old_desc_blk;
	if (ret_new_desc_blk)
		*ret_new_desc_blk = new_desc_blk;
	if (ret_meta_bg)
		*ret_meta_bg = meta_bg;
	return (numblocks);
}


/*
 * This function forces out the primary superblock.  We need to only
 * write out those fields which we have changed, since if the
 * filesystem is mounted, it may have changed some of the other
 * fields.
 *
 * It takes as input a superblock which has already been byte swapped
 * (if necessary).
 *
 */
static errcode_t write_primary_superblock(ext2_filsys fs,
					  struct ext2_super_block *super)
{
	__u16		*old_super, *new_super;
	int		check_idx, write_idx, size;
	errcode_t	retval;

	if (!fs->io->manager->write_byte || !fs->orig_super) {
		io_channel_set_blksize(fs->io, SUPERBLOCK_OFFSET);
		retval = io_channel_write_blk(fs->io, 1, -SUPERBLOCK_SIZE,
					      super);
		io_channel_set_blksize(fs->io, fs->blocksize);
		return retval;
	}

	old_super = (__u16 *) fs->orig_super;
	new_super = (__u16 *) super;

	for (check_idx = 0; check_idx < SUPERBLOCK_SIZE/2; check_idx++) {
		if (old_super[check_idx] == new_super[check_idx])
			continue;
		write_idx = check_idx;
		for (check_idx++; check_idx < SUPERBLOCK_SIZE/2; check_idx++)
			if (old_super[check_idx] == new_super[check_idx])
				break;
		size = 2 * (check_idx - write_idx);
#if 0
		printf("Writing %d bytes starting at %d\n",
		       size, write_idx*2);
#endif
		retval = io_channel_write_byte(fs->io,
			       SUPERBLOCK_OFFSET + (2 * write_idx), size,
					       new_super + write_idx);
		if (retval)
			return retval;
	}
	memcpy(fs->orig_super, super, SUPERBLOCK_SIZE);
	return 0;
}


/*
 * Updates the revision to EXT2_DYNAMIC_REV
 */
void ext2fs_update_dynamic_rev(ext2_filsys fs)
{
	struct ext2_super_block *sb = fs->super;

	if (sb->s_rev_level > EXT2_GOOD_OLD_REV)
		return;

	sb->s_rev_level = EXT2_DYNAMIC_REV;
	sb->s_first_ino = EXT2_GOOD_OLD_FIRST_INO;
	sb->s_inode_size = EXT2_GOOD_OLD_INODE_SIZE;
	/* s_uuid is handled by e2fsck already */
	/* other fields should be left alone */
}

static errcode_t write_backup_super(ext2_filsys fs, dgrp_t group,
				    blk_t group_block,
				    struct ext2_super_block *super_shadow)
{
	dgrp_t	sgrp = group;
	
	if (sgrp > ((1 << 16) - 1))
		sgrp = (1 << 16) - 1;
#ifdef EXT2FS_ENABLE_SWAPFS
	if (fs->flags & EXT2_FLAG_SWAP_BYTES)
		super_shadow->s_block_group_nr = ext2fs_swab16(sgrp);
	else
#endif
		fs->super->s_block_group_nr = sgrp;

	return io_channel_write_blk(fs->io, group_block, -SUPERBLOCK_SIZE, 
				    super_shadow);
}


errcode_t ext2fs_flush(ext2_filsys fs)
{
	dgrp_t		i,j;
	errcode_t	retval;
	unsigned long	fs_state;
	__u32		feature_incompat;
	struct ext2_super_block *super_shadow = 0;
	struct ext2_group_desc *group_shadow = 0;
	struct ext2_group_desc *s, *t;
	char	*group_ptr;
	int	old_desc_blocks;
	
	EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);

	fs_state = fs->super->s_state;
	feature_incompat = fs->super->s_feature_incompat;

	fs->super->s_wtime = fs->now ? fs->now : time(NULL);
	fs->super->s_block_group_nr = 0;
#ifdef EXT2FS_ENABLE_SWAPFS
	if (fs->flags & EXT2_FLAG_SWAP_BYTES) {
		retval = EXT2_ET_NO_MEMORY;
		retval = ext2fs_get_mem(SUPERBLOCK_SIZE, &super_shadow);
		if (retval)
			goto errout;
		retval = ext2fs_get_array(fs->blocksize, fs->desc_blocks,
					&group_shadow);
		if (retval)
			goto errout;
		memset(group_shadow, 0, (size_t) fs->blocksize *
		       fs->desc_blocks);

		/* swap the group descriptors */
		for (j=0, s=fs->group_desc, t=group_shadow;
		     j < fs->group_desc_count; j++, t++, s++) {
			*t = *s;
			ext2fs_swap_group_desc(t);
		}
	} else {
		super_shadow = fs->super;
		group_shadow = fs->group_desc;
	}
#else
	super_shadow = fs->super;
	group_shadow = fs->group_desc;
#endif
	
	/*
	 * Set the state of the FS to be non-valid.  (The state has
	 * already been backed up earlier, and will be restored after
	 * we write out the backup superblocks.)
	 */
	fs->super->s_state &= ~EXT2_VALID_FS;
	fs->super->s_feature_incompat &= ~EXT3_FEATURE_INCOMPAT_RECOVER;
#ifdef EXT2FS_ENABLE_SWAPFS
	if (fs->flags & EXT2_FLAG_SWAP_BYTES) {
		*super_shadow = *fs->super;
		ext2fs_swap_super(super_shadow);
	}
#endif

	/*
	 * If this is an external journal device, don't write out the
	 * block group descriptors or any of the backup superblocks
	 */
	if (fs->super->s_feature_incompat &
	    EXT3_FEATURE_INCOMPAT_JOURNAL_DEV)
		goto write_primary_superblock_only;

	/*
	 * Write out the master group descriptors, and the backup
	 * superblocks and group descriptors.
	 */
	group_ptr = (char *) group_shadow;
	if (fs->super->s_feature_incompat & EXT2_FEATURE_INCOMPAT_META_BG)
		old_desc_blocks = fs->super->s_first_meta_bg;
	else
		old_desc_blocks = fs->desc_blocks;

	for (i = 0; i < fs->group_desc_count; i++) {
		blk_t	super_blk, old_desc_blk, new_desc_blk;
		int	meta_bg;

		ext2fs_super_and_bgd_loc(fs, i, &super_blk, &old_desc_blk, 
					 &new_desc_blk, &meta_bg);

		if (!(fs->flags & EXT2_FLAG_MASTER_SB_ONLY) &&i && super_blk) {
			retval = write_backup_super(fs, i, super_blk,
						    super_shadow);
			if (retval)
				goto errout;
		}
		if (fs->flags & EXT2_FLAG_SUPER_ONLY)
			continue;
		if ((old_desc_blk) && 
		    (!(fs->flags & EXT2_FLAG_MASTER_SB_ONLY) || (i == 0))) {
			retval = io_channel_write_blk(fs->io,
			      old_desc_blk, old_desc_blocks, group_ptr);
			if (retval)
				goto errout;
		}
		if (new_desc_blk) {
			retval = io_channel_write_blk(fs->io, new_desc_blk,
				1, group_ptr + (meta_bg*fs->blocksize));
			if (retval)
				goto errout;
		}
	}

	/*
	 * If the write_bitmaps() function is present, call it to
	 * flush the bitmaps.  This is done this way so that a simple
	 * program that doesn't mess with the bitmaps doesn't need to
	 * drag in the bitmaps.c code.
	 */
	if (fs->write_bitmaps) {
		retval = fs->write_bitmaps(fs);
		if (retval)
			goto errout;
	}

write_primary_superblock_only:
	/*
	 * Write out master superblock.  This has to be done
	 * separately, since it is located at a fixed location
	 * (SUPERBLOCK_OFFSET).  We flush all other pending changes
	 * out to disk first, just to avoid a race condition with an
	 * insy-tinsy window....
	 */

	fs->super->s_block_group_nr = 0;
	fs->super->s_state = fs_state;
	fs->super->s_feature_incompat = feature_incompat;
#ifdef EXT2FS_ENABLE_SWAPFS
	if (fs->flags & EXT2_FLAG_SWAP_BYTES) {
		*super_shadow = *fs->super;
		ext2fs_swap_super(super_shadow);
	}
#endif

	retval = io_channel_flush(fs->io);
	retval = write_primary_superblock(fs, super_shadow);
	if (retval)
		goto errout;

	fs->flags &= ~EXT2_FLAG_DIRTY;

	retval = io_channel_flush(fs->io);
errout:
	fs->super->s_state = fs_state;
	if (fs->flags & EXT2_FLAG_SWAP_BYTES) {
		if (super_shadow)
			ext2fs_free_mem(&super_shadow);
		if (group_shadow)
			ext2fs_free_mem(&group_shadow);
	}
	return retval;
}

errcode_t write_mmp_clean(ext2_filsys fs)
{
	blk_t mmp_blk = fs->super->s_mmp_block;
	char *buf = fs->mmp_buf, *buf_cmp;
	struct mmp_struct *mmp, *mmp_cmp;
	errcode_t retval;

	retval = ext2fs_get_mem(fs->blocksize, &buf_cmp);
	if (retval)
		goto mmp_error;

	retval = ext2fs_read_mmp(fs, mmp_blk, buf_cmp);
	if (retval)
		goto mmp_error;
	mmp_cmp = (struct mmp_struct *) buf_cmp;

	/*
	 * This is important since we may come here just after when MMP feature
	 * is set and fs->mmp_buf is NULL
	 */
	if (!buf)
		goto check_skipped;

	/*
	 * Make sure that the MMP block is not changed.
	 */
	mmp = (struct mmp_struct *) buf;
	if (memcmp(mmp, mmp_cmp, sizeof(struct mmp_struct)))
		return EXT2_ET_MMP_FSCK_ABORT;

check_skipped:
	mmp_cmp->mmp_seq = EXT2_MMP_SEQ_CLEAN;
	retval = ext2fs_write_mmp(fs, mmp_blk, buf_cmp);

mmp_error:
	if (buf)
		ext2fs_free_mem(&buf);
	if (buf_cmp)
		ext2fs_free_mem(&buf_cmp);

	return retval;
}


errcode_t ext2fs_close(ext2_filsys fs)
{
	errcode_t	retval;
	
	EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);

	if ((fs->super->s_feature_incompat & EXT4_FEATURE_INCOMPAT_MMP) &&
	    (fs->flags & EXT2_FLAG_RW) && !(fs->flags & EXT2_FLAG_SKIP_MMP)) {
		retval = write_mmp_clean(fs);
		if (retval)
			return retval;
	}

	if (fs->flags & EXT2_FLAG_DIRTY) {
		retval = ext2fs_flush(fs);
		if (retval)
			return retval;
	}
	if (fs->write_bitmaps) {
		retval = fs->write_bitmaps(fs);
		if (retval)
			return retval;
	}
	ext2fs_free(fs);
	return 0;
}