closefs.c revision ef344e13d2125e9dae3764b98f9fe3a170cd79e2 
1/*
2 * closefs.c --- close an ext2 filesystem
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#include <stdio.h>
13#if HAVE_UNISTD_H
14#include <unistd.h>
15#endif
16#include <time.h>
17#include <string.h>
18
19#include "ext2_fs.h"
20#include "ext2fsP.h"
21
22static int test_root(int a, int b)
23{
24	if (a == 0)
25		return 1;
26	while (1) {
27		if (a == 1)
28			return 1;
29		if (a % b)
30			return 0;
31		a = a / b;
32	}
33}
34
35int ext2fs_bg_has_super(ext2_filsys fs, int group_block)
36{
37	if (!(fs->super->s_feature_ro_compat &
38	      EXT2_FEATURE_RO_COMPAT_SPARSE_SUPER))
39		return 1;
40
41	if (test_root(group_block, 3) || (test_root(group_block, 5)) ||
42	    test_root(group_block, 7))
43		return 1;
44
45	return 0;
46}
47
48int ext2fs_super_and_bgd_loc(ext2_filsys fs,
49			     dgrp_t group,
50			     blk_t *ret_super_blk,
51			     blk_t *ret_old_desc_blk,
52			     blk_t *ret_new_desc_blk,
53			     int *ret_meta_bg)
54{
55	blk_t	group_block, super_blk = 0, old_desc_blk = 0, new_desc_blk = 0;
56	int	numblocks, j, has_super, meta_bg_size, meta_bg;
57	int	old_desc_blocks;
58
59	group_block = fs->super->s_first_data_block +
60		(group * fs->super->s_blocks_per_group);
61
62	if (fs->super->s_feature_incompat & EXT2_FEATURE_INCOMPAT_META_BG)
63		old_desc_blocks = fs->super->s_first_meta_bg;
64	else
65		old_desc_blocks = fs->desc_blocks;
66
67	if (group == fs->group_desc_count-1) {
68		numblocks = (fs->super->s_blocks_count -
69			     fs->super->s_first_data_block) %
70			fs->super->s_blocks_per_group;
71		if (!numblocks)
72			numblocks = fs->super->s_blocks_per_group;
73	} else
74		numblocks = fs->super->s_blocks_per_group;
75
76	has_super = ext2fs_bg_has_super(fs, group);
77
78	if (has_super) {
79		super_blk = group_block;
80		numblocks--;
81	}
82	meta_bg_size = (fs->blocksize / sizeof (struct ext2_group_desc));
83	meta_bg = group / meta_bg_size;
84
85	if (!(fs->super->s_feature_incompat & EXT2_FEATURE_INCOMPAT_META_BG) ||
86	    (meta_bg < fs->super->s_first_meta_bg)) {
87		if (has_super) {
88			old_desc_blk = group_block + 1;
89			numblocks -= old_desc_blocks;
90		}
91	} else {
92		if (((group % meta_bg_size) == 0) ||
93		    ((group % meta_bg_size) == 1) ||
94		    ((group % meta_bg_size) == (meta_bg_size-1))) {
95			if (has_super)
96				has_super = 1;
97			new_desc_blk = group_block + has_super;
98			numblocks--;
99		}
100	}
101
102	numblocks -= 2 + fs->inode_blocks_per_group;
103
104	if (ret_super_blk)
105		*ret_super_blk = super_blk;
106	if (ret_old_desc_blk)
107		*ret_old_desc_blk = old_desc_blk;
108	if (ret_new_desc_blk)
109		*ret_new_desc_blk = new_desc_blk;
110	if (ret_meta_bg)
111		*ret_meta_bg = meta_bg;
112	return (numblocks);
113}
114
115
116/*
117 * This function forces out the primary superblock.  We need to only
118 * write out those fields which we have changed, since if the
119 * filesystem is mounted, it may have changed some of the other
120 * fields.
121 *
122 * It takes as input a superblock which has already been byte swapped
123 * (if necessary).
124 *
125 */
126static errcode_t write_primary_superblock(ext2_filsys fs,
127					  struct ext2_super_block *super)
128{
129	__u16		*old_super, *new_super;
130	int		check_idx, write_idx, size;
131	errcode_t	retval;
132
133	if (!fs->io->manager->write_byte || !fs->orig_super) {
134		io_channel_set_blksize(fs->io, SUPERBLOCK_OFFSET);
135		retval = io_channel_write_blk(fs->io, 1, -SUPERBLOCK_SIZE,
136					      super);
137		io_channel_set_blksize(fs->io, fs->blocksize);
138		return retval;
139	}
140
141	old_super = (__u16 *) fs->orig_super;
142	new_super = (__u16 *) super;
143
144	for (check_idx = 0; check_idx < SUPERBLOCK_SIZE/2; check_idx++) {
145		if (old_super[check_idx] == new_super[check_idx])
146			continue;
147		write_idx = check_idx;
148		for (check_idx++; check_idx < SUPERBLOCK_SIZE/2; check_idx++)
149			if (old_super[check_idx] == new_super[check_idx])
150				break;
151		size = 2 * (check_idx - write_idx);
152#if 0
153		printf("Writing %d bytes starting at %d\n",
154		       size, write_idx*2);
155#endif
156		retval = io_channel_write_byte(fs->io,
157			       SUPERBLOCK_OFFSET + (2 * write_idx), size,
158					       new_super + write_idx);
159		if (retval)
160			return retval;
161	}
162	memcpy(fs->orig_super, super, SUPERBLOCK_SIZE);
163	return 0;
164}
165
166
167/*
168 * Updates the revision to EXT2_DYNAMIC_REV
169 */
170void ext2fs_update_dynamic_rev(ext2_filsys fs)
171{
172	struct ext2_super_block *sb = fs->super;
173
174	if (sb->s_rev_level > EXT2_GOOD_OLD_REV)
175		return;
176
177	sb->s_rev_level = EXT2_DYNAMIC_REV;
178	sb->s_first_ino = EXT2_GOOD_OLD_FIRST_INO;
179	sb->s_inode_size = EXT2_GOOD_OLD_INODE_SIZE;
180	/* s_uuid is handled by e2fsck already */
181	/* other fields should be left alone */
182}
183
184static errcode_t write_backup_super(ext2_filsys fs, dgrp_t group,
185				    blk_t group_block,
186				    struct ext2_super_block *super_shadow)
187{
188	dgrp_t	sgrp = group;
189
190	if (sgrp > ((1 << 16) - 1))
191		sgrp = (1 << 16) - 1;
192#ifdef EXT2FS_ENABLE_SWAPFS
193	if (fs->flags & EXT2_FLAG_SWAP_BYTES)
194		super_shadow->s_block_group_nr = ext2fs_swab16(sgrp);
195	else
196#endif
197		fs->super->s_block_group_nr = sgrp;
198
199	return io_channel_write_blk(fs->io, group_block, -SUPERBLOCK_SIZE,
200				    super_shadow);
201}
202
203
204errcode_t ext2fs_flush(ext2_filsys fs)
205{
206	dgrp_t		i,j;
207	blk_t		group_block;
208	errcode_t	retval;
209	unsigned long	fs_state;
210	struct ext2_super_block *super_shadow = 0;
211	struct ext2_group_desc *group_shadow = 0;
212	struct ext2_group_desc *s, *t;
213	char	*group_ptr;
214	int	old_desc_blocks;
215
216	EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
217
218	fs_state = fs->super->s_state;
219
220	fs->super->s_wtime = time(NULL);
221	fs->super->s_block_group_nr = 0;
222#ifdef EXT2FS_ENABLE_SWAPFS
223	if (fs->flags & EXT2_FLAG_SWAP_BYTES) {
224		retval = EXT2_ET_NO_MEMORY;
225		retval = ext2fs_get_mem(SUPERBLOCK_SIZE, &super_shadow);
226		if (retval)
227			goto errout;
228		retval = ext2fs_get_mem((size_t)(fs->blocksize *
229						 fs->desc_blocks),
230					&group_shadow);
231		if (retval)
232			goto errout;
233		memset(group_shadow, 0, (size_t) fs->blocksize *
234		       fs->desc_blocks);
235
236		/* swap the superblock */
237		*super_shadow = *fs->super;
238		ext2fs_swap_super(super_shadow);
239
240		/* swap the group descriptors */
241		for (j=0, s=fs->group_desc, t=group_shadow;
242		     j < fs->group_desc_count; j++, t++, s++) {
243			*t = *s;
244			ext2fs_swap_group_desc(t);
245		}
246	} else {
247		super_shadow = fs->super;
248		group_shadow = fs->group_desc;
249	}
250#else
251	super_shadow = fs->super;
252	group_shadow = fs->group_desc;
253#endif
254
255	/*
256	 * Write out master superblock.  This has to be done
257	 * separately, since it is located at a fixed location
258	 * (SUPERBLOCK_OFFSET).
259	 */
260	retval = write_primary_superblock(fs, super_shadow);
261	if (retval)
262		goto errout;
263
264	/*
265	 * If this is an external journal device, don't write out the
266	 * block group descriptors or any of the backup superblocks
267	 */
268	if (fs->super->s_feature_incompat &
269	    EXT3_FEATURE_INCOMPAT_JOURNAL_DEV) {
270		retval = 0;
271		goto errout;
272	}
273
274	/*
275	 * Set the state of the FS to be non-valid.  (The state has
276	 * already been backed up earlier, and will be restored when
277	 * we exit.)
278	 */
279	fs->super->s_state &= ~EXT2_VALID_FS;
280#ifdef EXT2FS_ENABLE_SWAPFS
281	if (fs->flags & EXT2_FLAG_SWAP_BYTES) {
282		*super_shadow = *fs->super;
283		ext2fs_swap_super(super_shadow);
284	}
285#endif
286
287	/*
288	 * Write out the master group descriptors, and the backup
289	 * superblocks and group descriptors.
290	 */
291	group_block = fs->super->s_first_data_block;
292	group_ptr = (char *) group_shadow;
293	if (fs->super->s_feature_incompat & EXT2_FEATURE_INCOMPAT_META_BG)
294		old_desc_blocks = fs->super->s_first_meta_bg;
295	else
296		old_desc_blocks = fs->desc_blocks;
297
298	for (i = 0; i < fs->group_desc_count; i++) {
299		blk_t	super_blk, old_desc_blk, new_desc_blk;
300		int	meta_bg;
301
302		ext2fs_super_and_bgd_loc(fs, i, &super_blk, &old_desc_blk,
303					 &new_desc_blk, &meta_bg);
304
305		if (!(fs->flags & EXT2_FLAG_MASTER_SB_ONLY) &&i && super_blk) {
306			retval = write_backup_super(fs, i, super_blk,
307						    super_shadow);
308			if (retval)
309				goto errout;
310		}
311		if (fs->flags & EXT2_FLAG_SUPER_ONLY)
312			continue;
313		if ((old_desc_blk) &&
314		    (!(fs->flags & EXT2_FLAG_MASTER_SB_ONLY) || (i == 0))) {
315			retval = io_channel_write_blk(fs->io,
316			      old_desc_blk, old_desc_blocks, group_ptr);
317			if (retval)
318				goto errout;
319		}
320		if (new_desc_blk) {
321			retval = io_channel_write_blk(fs->io, new_desc_blk,
322				1, group_ptr + (meta_bg*fs->blocksize));
323			if (retval)
324				goto errout;
325		}
326	}
327	fs->super->s_block_group_nr = 0;
328
329	/*
330	 * If the write_bitmaps() function is present, call it to
331	 * flush the bitmaps.  This is done this way so that a simple
332	 * program that doesn't mess with the bitmaps doesn't need to
333	 * drag in the bitmaps.c code.
334	 */
335	if (fs->write_bitmaps) {
336		retval = fs->write_bitmaps(fs);
337		if (retval)
338			goto errout;
339	}
340
341	fs->flags &= ~EXT2_FLAG_DIRTY;
342
343	/*
344	 * Flush the blocks out to disk
345	 */
346	retval = io_channel_flush(fs->io);
347errout:
348	fs->super->s_state = fs_state;
349	if (fs->flags & EXT2_FLAG_SWAP_BYTES) {
350		if (super_shadow)
351			ext2fs_free_mem(&super_shadow);
352		if (group_shadow)
353			ext2fs_free_mem(&group_shadow);
354	}
355	return retval;
356}
357
358errcode_t ext2fs_close(ext2_filsys fs)
359{
360	errcode_t	retval;
361
362	EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
363
364	if (fs->flags & EXT2_FLAG_DIRTY) {
365		retval = ext2fs_flush(fs);
366		if (retval)
367			return retval;
368	}
369	if (fs->write_bitmaps) {
370		retval = fs->write_bitmaps(fs);
371		if (retval)
372			return retval;
373	}
374	ext2fs_free(fs);
375	return 0;
376}
377
378