closefs.c revision 0d961040fe9ad927254b5a0e1a4de7bedadd8579 
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	unsigned int meta_bg, meta_bg_size;
57	int	numblocks, has_super;
58	int	old_desc_blocks;
59
60	group_block = fs->super->s_first_data_block +
61		(group * fs->super->s_blocks_per_group);
62
63	if (fs->super->s_feature_incompat & EXT2_FEATURE_INCOMPAT_META_BG)
64		old_desc_blocks = fs->super->s_first_meta_bg;
65	else
66		old_desc_blocks =
67			fs->desc_blocks + fs->super->s_reserved_gdt_blocks;
68
69	if (group == fs->group_desc_count-1) {
70		numblocks = (fs->super->s_blocks_count -
71			     fs->super->s_first_data_block) %
72			fs->super->s_blocks_per_group;
73		if (!numblocks)
74			numblocks = fs->super->s_blocks_per_group;
75	} else
76		numblocks = fs->super->s_blocks_per_group;
77
78	has_super = ext2fs_bg_has_super(fs, group);
79
80	if (has_super) {
81		super_blk = group_block;
82		numblocks--;
83	}
84	meta_bg_size = (fs->blocksize / sizeof (struct ext2_group_desc));
85	meta_bg = group / meta_bg_size;
86
87	if (!(fs->super->s_feature_incompat & EXT2_FEATURE_INCOMPAT_META_BG) ||
88	    (meta_bg < fs->super->s_first_meta_bg)) {
89		if (has_super) {
90			old_desc_blk = group_block + 1;
91			numblocks -= old_desc_blocks;
92		}
93	} else {
94		if (((group % meta_bg_size) == 0) ||
95		    ((group % meta_bg_size) == 1) ||
96		    ((group % meta_bg_size) == (meta_bg_size-1))) {
97			if (has_super)
98				has_super = 1;
99			new_desc_blk = group_block + has_super;
100			numblocks--;
101		}
102	}
103
104	numblocks -= 2 + fs->inode_blocks_per_group;
105
106	if (ret_super_blk)
107		*ret_super_blk = super_blk;
108	if (ret_old_desc_blk)
109		*ret_old_desc_blk = old_desc_blk;
110	if (ret_new_desc_blk)
111		*ret_new_desc_blk = new_desc_blk;
112	if (ret_meta_bg)
113		*ret_meta_bg = meta_bg;
114	return (numblocks);
115}
116
117
118/*
119 * This function forces out the primary superblock.  We need to only
120 * write out those fields which we have changed, since if the
121 * filesystem is mounted, it may have changed some of the other
122 * fields.
123 *
124 * It takes as input a superblock which has already been byte swapped
125 * (if necessary).
126 *
127 */
128static errcode_t write_primary_superblock(ext2_filsys fs,
129					  struct ext2_super_block *super)
130{
131	__u16		*old_super, *new_super;
132	int		check_idx, write_idx, size;
133	errcode_t	retval;
134
135	if (!fs->io->manager->write_byte || !fs->orig_super) {
136		io_channel_set_blksize(fs->io, SUPERBLOCK_OFFSET);
137		retval = io_channel_write_blk(fs->io, 1, -SUPERBLOCK_SIZE,
138					      super);
139		io_channel_set_blksize(fs->io, fs->blocksize);
140		return retval;
141	}
142
143	old_super = (__u16 *) fs->orig_super;
144	new_super = (__u16 *) super;
145
146	for (check_idx = 0; check_idx < SUPERBLOCK_SIZE/2; check_idx++) {
147		if (old_super[check_idx] == new_super[check_idx])
148			continue;
149		write_idx = check_idx;
150		for (check_idx++; check_idx < SUPERBLOCK_SIZE/2; check_idx++)
151			if (old_super[check_idx] == new_super[check_idx])
152				break;
153		size = 2 * (check_idx - write_idx);
154#if 0
155		printf("Writing %d bytes starting at %d\n",
156		       size, write_idx*2);
157#endif
158		retval = io_channel_write_byte(fs->io,
159			       SUPERBLOCK_OFFSET + (2 * write_idx), size,
160					       new_super + write_idx);
161		if (retval)
162			return retval;
163	}
164	memcpy(fs->orig_super, super, SUPERBLOCK_SIZE);
165	return 0;
166}
167
168
169/*
170 * Updates the revision to EXT2_DYNAMIC_REV
171 */
172void ext2fs_update_dynamic_rev(ext2_filsys fs)
173{
174	struct ext2_super_block *sb = fs->super;
175
176	if (sb->s_rev_level > EXT2_GOOD_OLD_REV)
177		return;
178
179	sb->s_rev_level = EXT2_DYNAMIC_REV;
180	sb->s_first_ino = EXT2_GOOD_OLD_FIRST_INO;
181	sb->s_inode_size = EXT2_GOOD_OLD_INODE_SIZE;
182	/* s_uuid is handled by e2fsck already */
183	/* other fields should be left alone */
184}
185
186static errcode_t write_backup_super(ext2_filsys fs, dgrp_t group,
187				    blk_t group_block,
188				    struct ext2_super_block *super_shadow)
189{
190	dgrp_t	sgrp = group;
191
192	if (sgrp > ((1 << 16) - 1))
193		sgrp = (1 << 16) - 1;
194#ifdef EXT2FS_ENABLE_SWAPFS
195	if (fs->flags & EXT2_FLAG_SWAP_BYTES)
196		super_shadow->s_block_group_nr = ext2fs_swab16(sgrp);
197	else
198#endif
199		fs->super->s_block_group_nr = sgrp;
200
201	return io_channel_write_blk(fs->io, group_block, -SUPERBLOCK_SIZE,
202				    super_shadow);
203}
204
205
206errcode_t ext2fs_flush(ext2_filsys fs)
207{
208	dgrp_t		i,j;
209	blk_t		group_block;
210	errcode_t	retval;
211	unsigned long	fs_state;
212	struct ext2_super_block *super_shadow = 0;
213	struct ext2_group_desc *group_shadow = 0;
214	struct ext2_group_desc *s, *t;
215	char	*group_ptr;
216	int	old_desc_blocks;
217
218	EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
219
220	fs_state = fs->super->s_state;
221
222	fs->super->s_wtime = fs->now ? fs->now : time(NULL);
223	fs->super->s_block_group_nr = 0;
224#ifdef EXT2FS_ENABLE_SWAPFS
225	if (fs->flags & EXT2_FLAG_SWAP_BYTES) {
226		retval = EXT2_ET_NO_MEMORY;
227		retval = ext2fs_get_mem(SUPERBLOCK_SIZE, &super_shadow);
228		if (retval)
229			goto errout;
230		retval = ext2fs_get_mem((size_t)(fs->blocksize *
231						 fs->desc_blocks),
232					&group_shadow);
233		if (retval)
234			goto errout;
235		memset(group_shadow, 0, (size_t) fs->blocksize *
236		       fs->desc_blocks);
237
238		/* swap the group descriptors */
239		for (j=0, s=fs->group_desc, t=group_shadow;
240		     j < fs->group_desc_count; j++, t++, s++) {
241			*t = *s;
242			ext2fs_swap_group_desc(t);
243		}
244	} else {
245		super_shadow = fs->super;
246		group_shadow = fs->group_desc;
247	}
248#else
249	super_shadow = fs->super;
250	group_shadow = fs->group_desc;
251#endif
252
253	/*
254	 * Set the state of the FS to be non-valid.  (The state has
255	 * already been backed up earlier, and will be restored after
256	 * we write out the backup superblocks.)
257	 */
258	fs->super->s_state &= ~EXT2_VALID_FS;
259#ifdef EXT2FS_ENABLE_SWAPFS
260	if (fs->flags & EXT2_FLAG_SWAP_BYTES) {
261		*super_shadow = *fs->super;
262		ext2fs_swap_super(super_shadow);
263	}
264#endif
265
266	/*
267	 * If this is an external journal device, don't write out the
268	 * block group descriptors or any of the backup superblocks
269	 */
270	if (fs->super->s_feature_incompat &
271	    EXT3_FEATURE_INCOMPAT_JOURNAL_DEV)
272		goto write_primary_superblock_only;
273
274	/*
275	 * Write out the master group descriptors, and the backup
276	 * superblocks and group descriptors.
277	 */
278	group_block = fs->super->s_first_data_block;
279	group_ptr = (char *) group_shadow;
280	if (fs->super->s_feature_incompat & EXT2_FEATURE_INCOMPAT_META_BG)
281		old_desc_blocks = fs->super->s_first_meta_bg;
282	else
283		old_desc_blocks = fs->desc_blocks;
284
285	for (i = 0; i < fs->group_desc_count; i++) {
286		blk_t	super_blk, old_desc_blk, new_desc_blk;
287		int	meta_bg;
288
289		ext2fs_super_and_bgd_loc(fs, i, &super_blk, &old_desc_blk,
290					 &new_desc_blk, &meta_bg);
291
292		if (!(fs->flags & EXT2_FLAG_MASTER_SB_ONLY) &&i && super_blk) {
293			retval = write_backup_super(fs, i, super_blk,
294						    super_shadow);
295			if (retval)
296				goto errout;
297		}
298		if (fs->flags & EXT2_FLAG_SUPER_ONLY)
299			continue;
300		if ((old_desc_blk) &&
301		    (!(fs->flags & EXT2_FLAG_MASTER_SB_ONLY) || (i == 0))) {
302			retval = io_channel_write_blk(fs->io,
303			      old_desc_blk, old_desc_blocks, group_ptr);
304			if (retval)
305				goto errout;
306		}
307		if (new_desc_blk) {
308			retval = io_channel_write_blk(fs->io, new_desc_blk,
309				1, group_ptr + (meta_bg*fs->blocksize));
310			if (retval)
311				goto errout;
312		}
313	}
314
315	/*
316	 * If the write_bitmaps() function is present, call it to
317	 * flush the bitmaps.  This is done this way so that a simple
318	 * program that doesn't mess with the bitmaps doesn't need to
319	 * drag in the bitmaps.c code.
320	 */
321	if (fs->write_bitmaps) {
322		retval = fs->write_bitmaps(fs);
323		if (retval)
324			goto errout;
325	}
326
327write_primary_superblock_only:
328	/*
329	 * Write out master superblock.  This has to be done
330	 * separately, since it is located at a fixed location
331	 * (SUPERBLOCK_OFFSET).  We flush all other pending changes
332	 * out to disk first, just to avoid a race condition with an
333	 * insy-tinsy window....
334	 */
335
336	fs->super->s_block_group_nr = 0;
337	fs->super->s_state = fs_state;
338#ifdef EXT2FS_ENABLE_SWAPFS
339	if (fs->flags & EXT2_FLAG_SWAP_BYTES) {
340		*super_shadow = *fs->super;
341		ext2fs_swap_super(super_shadow);
342	}
343#endif
344
345	retval = io_channel_flush(fs->io);
346	retval = write_primary_superblock(fs, super_shadow);
347	if (retval)
348		goto errout;
349
350	fs->flags &= ~EXT2_FLAG_DIRTY;
351
352	retval = io_channel_flush(fs->io);
353errout:
354	fs->super->s_state = fs_state;
355	if (fs->flags & EXT2_FLAG_SWAP_BYTES) {
356		if (super_shadow)
357			ext2fs_free_mem(&super_shadow);
358		if (group_shadow)
359			ext2fs_free_mem(&group_shadow);
360	}
361	return retval;
362}
363
364errcode_t ext2fs_close(ext2_filsys fs)
365{
366	errcode_t	retval;
367
368	EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
369
370	if (fs->flags & EXT2_FLAG_DIRTY) {
371		retval = ext2fs_flush(fs);
372		if (retval)
373			return retval;
374	}
375	if (fs->write_bitmaps) {
376		retval = fs->write_bitmaps(fs);
377		if (retval)
378			return retval;
379	}
380	ext2fs_free(fs);
381	return 0;
382}
383
384