closefs.c revision d323f8fb369089b97d6f3bf0f8d64ceeab0b10f5 
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
22int ext2fs_super_and_bgd_loc(ext2_filsys fs,
23			     dgrp_t group,
24			     blk_t *ret_super_blk,
25			     blk_t *ret_old_desc_blk,
26			     blk_t *ret_new_desc_blk,
27			     int *ret_meta_bg)
28{
29	blk_t	group_block, super_blk = 0, old_desc_blk = 0, new_desc_blk = 0;
30	unsigned int meta_bg, meta_bg_size;
31	int	numblocks, has_super;
32	int	old_desc_blocks;
33
34	group_block = fs->super->s_first_data_block +
35		(group * fs->super->s_blocks_per_group);
36
37	if (fs->super->s_feature_incompat & EXT2_FEATURE_INCOMPAT_META_BG)
38		old_desc_blocks = fs->super->s_first_meta_bg;
39	else
40		old_desc_blocks =
41			fs->desc_blocks + fs->super->s_reserved_gdt_blocks;
42
43	if (group == fs->group_desc_count-1) {
44		numblocks = (fs->super->s_blocks_count -
45			     fs->super->s_first_data_block) %
46			fs->super->s_blocks_per_group;
47		if (!numblocks)
48			numblocks = fs->super->s_blocks_per_group;
49	} else
50		numblocks = fs->super->s_blocks_per_group;
51
52	has_super = ext2fs_bg_has_super(fs, group);
53
54	if (has_super) {
55		super_blk = group_block;
56		numblocks--;
57	}
58	meta_bg_size = (fs->blocksize / sizeof (struct ext2_group_desc));
59	meta_bg = group / meta_bg_size;
60
61	if (!(fs->super->s_feature_incompat & EXT2_FEATURE_INCOMPAT_META_BG) ||
62	    (meta_bg < fs->super->s_first_meta_bg)) {
63		if (has_super) {
64			old_desc_blk = group_block + 1;
65			numblocks -= old_desc_blocks;
66		}
67	} else {
68		if (((group % meta_bg_size) == 0) ||
69		    ((group % meta_bg_size) == 1) ||
70		    ((group % meta_bg_size) == (meta_bg_size-1))) {
71			if (has_super)
72				has_super = 1;
73			new_desc_blk = group_block + has_super;
74			numblocks--;
75		}
76	}
77
78	numblocks -= 2 + fs->inode_blocks_per_group;
79
80	if (ret_super_blk)
81		*ret_super_blk = super_blk;
82	if (ret_old_desc_blk)
83		*ret_old_desc_blk = old_desc_blk;
84	if (ret_new_desc_blk)
85		*ret_new_desc_blk = new_desc_blk;
86	if (ret_meta_bg)
87		*ret_meta_bg = meta_bg;
88	return (numblocks);
89}
90
91
92/*
93 * This function forces out the primary superblock.  We need to only
94 * write out those fields which we have changed, since if the
95 * filesystem is mounted, it may have changed some of the other
96 * fields.
97 *
98 * It takes as input a superblock which has already been byte swapped
99 * (if necessary).
100 *
101 */
102static errcode_t write_primary_superblock(ext2_filsys fs,
103					  struct ext2_super_block *super)
104{
105	__u16		*old_super, *new_super;
106	int		check_idx, write_idx, size;
107	errcode_t	retval;
108
109	if (!fs->io->manager->write_byte || !fs->orig_super) {
110		io_channel_set_blksize(fs->io, SUPERBLOCK_OFFSET);
111		retval = io_channel_write_blk(fs->io, 1, -SUPERBLOCK_SIZE,
112					      super);
113		io_channel_set_blksize(fs->io, fs->blocksize);
114		return retval;
115	}
116
117	old_super = (__u16 *) fs->orig_super;
118	new_super = (__u16 *) super;
119
120	for (check_idx = 0; check_idx < SUPERBLOCK_SIZE/2; check_idx++) {
121		if (old_super[check_idx] == new_super[check_idx])
122			continue;
123		write_idx = check_idx;
124		for (check_idx++; check_idx < SUPERBLOCK_SIZE/2; check_idx++)
125			if (old_super[check_idx] == new_super[check_idx])
126				break;
127		size = 2 * (check_idx - write_idx);
128#if 0
129		printf("Writing %d bytes starting at %d\n",
130		       size, write_idx*2);
131#endif
132		retval = io_channel_write_byte(fs->io,
133			       SUPERBLOCK_OFFSET + (2 * write_idx), size,
134					       new_super + write_idx);
135		if (retval)
136			return retval;
137	}
138	memcpy(fs->orig_super, super, SUPERBLOCK_SIZE);
139	return 0;
140}
141
142
143/*
144 * Updates the revision to EXT2_DYNAMIC_REV
145 */
146void ext2fs_update_dynamic_rev(ext2_filsys fs)
147{
148	struct ext2_super_block *sb = fs->super;
149
150	if (sb->s_rev_level > EXT2_GOOD_OLD_REV)
151		return;
152
153	sb->s_rev_level = EXT2_DYNAMIC_REV;
154	sb->s_first_ino = EXT2_GOOD_OLD_FIRST_INO;
155	sb->s_inode_size = EXT2_GOOD_OLD_INODE_SIZE;
156	/* s_uuid is handled by e2fsck already */
157	/* other fields should be left alone */
158}
159
160static errcode_t write_backup_super(ext2_filsys fs, dgrp_t group,
161				    blk_t group_block,
162				    struct ext2_super_block *super_shadow)
163{
164	dgrp_t	sgrp = group;
165
166	if (sgrp > ((1 << 16) - 1))
167		sgrp = (1 << 16) - 1;
168#ifdef EXT2FS_ENABLE_SWAPFS
169	if (fs->flags & EXT2_FLAG_SWAP_BYTES)
170		super_shadow->s_block_group_nr = ext2fs_swab16(sgrp);
171	else
172#endif
173		fs->super->s_block_group_nr = sgrp;
174
175	return io_channel_write_blk(fs->io, group_block, -SUPERBLOCK_SIZE,
176				    super_shadow);
177}
178
179
180errcode_t ext2fs_flush(ext2_filsys fs)
181{
182	dgrp_t		i,j;
183	blk_t		group_block;
184	errcode_t	retval;
185	unsigned long	fs_state;
186	struct ext2_super_block *super_shadow = 0;
187	struct ext2_group_desc *group_shadow = 0;
188	struct ext2_group_desc *s, *t;
189	char	*group_ptr;
190	int	old_desc_blocks;
191
192	EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
193
194	fs_state = fs->super->s_state;
195
196	fs->super->s_wtime = time(NULL);
197	fs->super->s_block_group_nr = 0;
198#ifdef EXT2FS_ENABLE_SWAPFS
199	if (fs->flags & EXT2_FLAG_SWAP_BYTES) {
200		retval = EXT2_ET_NO_MEMORY;
201		retval = ext2fs_get_mem(SUPERBLOCK_SIZE, &super_shadow);
202		if (retval)
203			goto errout;
204		retval = ext2fs_get_mem((size_t)(fs->blocksize *
205						 fs->desc_blocks),
206					&group_shadow);
207		if (retval)
208			goto errout;
209		memset(group_shadow, 0, (size_t) fs->blocksize *
210		       fs->desc_blocks);
211
212		/* swap the group descriptors */
213		for (j=0, s=fs->group_desc, t=group_shadow;
214		     j < fs->group_desc_count; j++, t++, s++) {
215			*t = *s;
216			ext2fs_swap_group_desc(t);
217		}
218	} else {
219		super_shadow = fs->super;
220		group_shadow = fs->group_desc;
221	}
222#else
223	super_shadow = fs->super;
224	group_shadow = fs->group_desc;
225#endif
226
227	/*
228	 * If this is an external journal device, don't write out the
229	 * block group descriptors or any of the backup superblocks
230	 */
231	if (fs->super->s_feature_incompat &
232	    EXT3_FEATURE_INCOMPAT_JOURNAL_DEV)
233		goto write_primary_superblock_only;
234
235	/*
236	 * Set the state of the FS to be non-valid.  (The state has
237	 * already been backed up earlier, and will be restored after
238	 * we write out the backup superblocks.)
239	 */
240	fs->super->s_state &= ~EXT2_VALID_FS;
241#ifdef EXT2FS_ENABLE_SWAPFS
242	if (fs->flags & EXT2_FLAG_SWAP_BYTES) {
243		*super_shadow = *fs->super;
244		ext2fs_swap_super(super_shadow);
245	}
246#endif
247
248	/*
249	 * Write out the master group descriptors, and the backup
250	 * superblocks and group descriptors.
251	 */
252	group_block = fs->super->s_first_data_block;
253	group_ptr = (char *) group_shadow;
254	if (fs->super->s_feature_incompat & EXT2_FEATURE_INCOMPAT_META_BG)
255		old_desc_blocks = fs->super->s_first_meta_bg;
256	else
257		old_desc_blocks = fs->desc_blocks;
258
259	for (i = 0; i < fs->group_desc_count; i++) {
260		blk_t	super_blk, old_desc_blk, new_desc_blk;
261		int	meta_bg;
262
263		ext2fs_super_and_bgd_loc(fs, i, &super_blk, &old_desc_blk,
264					 &new_desc_blk, &meta_bg);
265
266		if (!(fs->flags & EXT2_FLAG_MASTER_SB_ONLY) &&i && super_blk) {
267			retval = write_backup_super(fs, i, super_blk,
268						    super_shadow);
269			if (retval)
270				goto errout;
271		}
272		if (fs->flags & EXT2_FLAG_SUPER_ONLY)
273			continue;
274		if ((old_desc_blk) &&
275		    (!(fs->flags & EXT2_FLAG_MASTER_SB_ONLY) || (i == 0))) {
276			retval = io_channel_write_blk(fs->io,
277			      old_desc_blk, old_desc_blocks, group_ptr);
278			if (retval)
279				goto errout;
280		}
281		if (new_desc_blk) {
282			retval = io_channel_write_blk(fs->io, new_desc_blk,
283				1, group_ptr + (meta_bg*fs->blocksize));
284			if (retval)
285				goto errout;
286		}
287	}
288	fs->super->s_block_group_nr = 0;
289	fs->super->s_state = fs_state;
290#ifdef EXT2FS_ENABLE_SWAPFS
291	if (fs->flags & EXT2_FLAG_SWAP_BYTES) {
292		*super_shadow = *fs->super;
293		ext2fs_swap_super(super_shadow);
294	}
295#endif
296
297	/*
298	 * If the write_bitmaps() function is present, call it to
299	 * flush the bitmaps.  This is done this way so that a simple
300	 * program that doesn't mess with the bitmaps doesn't need to
301	 * drag in the bitmaps.c code.
302	 */
303	if (fs->write_bitmaps) {
304		retval = fs->write_bitmaps(fs);
305		if (retval)
306			goto errout;
307	}
308
309write_primary_superblock_only:
310	/*
311	 * Write out master superblock.  This has to be done
312	 * separately, since it is located at a fixed location
313	 * (SUPERBLOCK_OFFSET).  We flush all other pending changes
314	 * out to disk first, just to avoid a race condition with an
315	 * insy-tinsy window....
316	 */
317	retval = io_channel_flush(fs->io);
318	retval = write_primary_superblock(fs, super_shadow);
319	if (retval)
320		goto errout;
321
322	fs->flags &= ~EXT2_FLAG_DIRTY;
323
324	retval = io_channel_flush(fs->io);
325errout:
326	fs->super->s_state = fs_state;
327	if (fs->flags & EXT2_FLAG_SWAP_BYTES) {
328		if (super_shadow)
329			ext2fs_free_mem(&super_shadow);
330		if (group_shadow)
331			ext2fs_free_mem(&group_shadow);
332	}
333	return retval;
334}
335
336errcode_t ext2fs_close(ext2_filsys fs)
337{
338	errcode_t	retval;
339
340	EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
341
342	if (fs->flags & EXT2_FLAG_DIRTY) {
343		retval = ext2fs_flush(fs);
344		if (retval)
345			return retval;
346	}
347	if (fs->write_bitmaps) {
348		retval = fs->write_bitmaps(fs);
349		if (retval)
350			return retval;
351	}
352	ext2fs_free(fs);
353	return 0;
354}
355
356