closefs.c revision a917d1ccf49605b3009f4e7225f00b81fc16100b 
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#if EXT2_FLAT_INCLUDES
20#include "ext2_fs.h"
21#else
22#include <linux/ext2_fs.h>
23#endif
24
25#include "ext2fsP.h"
26
27static int test_root(int a, int b)
28{
29	if (a == 0)
30		return 1;
31	while (1) {
32		if (a == 1)
33			return 1;
34		if (a % b)
35			return 0;
36		a = a / b;
37	}
38}
39
40int ext2fs_bg_has_super(ext2_filsys fs, int group_block)
41{
42#ifdef EXT2_FEATURE_RO_COMPAT_SPARSE_SUPER
43	struct ext2fs_sb	*s;
44
45	s = (struct ext2fs_sb *) fs->super;
46	if (!(s->s_feature_ro_compat & EXT2_FEATURE_RO_COMPAT_SPARSE_SUPER))
47		return 1;
48
49	if (test_root(group_block, 3) || (test_root(group_block, 5)) ||
50	    test_root(group_block, 7))
51		return 1;
52
53	return 0;
54#else
55	return 1;
56#endif
57}
58
59/*
60 * This function forces out the primary superblock.  We need to only
61 * write out those fields which we have changed, since if the
62 * filesystem is mounted, it may have changed some of the other
63 * fields.
64 *
65 * It takes as input a superblock which has already been byte swapped
66 * (if necessary).
67 *
68 */
69static errcode_t write_primary_superblock(ext2_filsys fs,
70					  struct ext2_super_block *super)
71{
72	__u16		*old_super, *new_super;
73	int		check_idx, write_idx, size;
74	errcode_t	retval;
75
76	if (!fs->io->manager->write_byte || !fs->orig_super) {
77		io_channel_set_blksize(fs->io, SUPERBLOCK_OFFSET);
78		retval = io_channel_write_blk(fs->io, 1, -SUPERBLOCK_SIZE,
79					      super);
80		io_channel_set_blksize(fs->io, fs->blocksize);
81		return retval;
82	}
83
84	old_super = (__u16 *) fs->orig_super;
85	new_super = (__u16 *) super;
86
87	for (check_idx = 0; check_idx < SUPERBLOCK_SIZE/2; check_idx++) {
88		if (old_super[check_idx] == new_super[check_idx])
89			continue;
90		write_idx = check_idx;
91		for (check_idx++; check_idx < SUPERBLOCK_SIZE/2; check_idx++)
92			if (old_super[check_idx] == new_super[check_idx])
93				break;
94		size = 2 * (check_idx - write_idx);
95#if 0
96		printf("Writing %d bytes starting at %d\n",
97		       size, write_idx*2);
98#endif
99		retval = io_channel_write_byte(fs->io,
100			       SUPERBLOCK_OFFSET + (2 * write_idx), size,
101					       new_super + write_idx);
102		if (retval)
103			return retval;
104	}
105	return 0;
106}
107
108
109/*
110 * Updates the revision to EXT2_DYNAMIC_REV
111 */
112void ext2fs_update_dynamic_rev(ext2_filsys fs)
113{
114	struct ext2_super_block *sb = fs->super;
115
116	if (sb->s_rev_level > EXT2_GOOD_OLD_REV)
117		return;
118
119	sb->s_rev_level = EXT2_DYNAMIC_REV;
120	sb->s_first_ino = EXT2_GOOD_OLD_FIRST_INO;
121	sb->s_inode_size = EXT2_GOOD_OLD_INODE_SIZE;
122	/* s_uuid is handled by e2fsck already */
123	/* other fields should be left alone */
124}
125
126errcode_t ext2fs_flush(ext2_filsys fs)
127{
128	dgrp_t		i,j,maxgroup,sgrp;
129	blk_t		group_block;
130	errcode_t	retval;
131	char		*group_ptr;
132	unsigned long	fs_state;
133	struct ext2_super_block *super_shadow = 0;
134	struct ext2_group_desc *group_shadow = 0;
135	struct ext2_group_desc *s, *t;
136	struct ext2fs_sb *sb, *sb_shadow;
137
138	EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
139
140	fs_state = fs->super->s_state;
141
142	fs->super->s_wtime = time(NULL);
143	sb = (struct ext2fs_sb *) fs->super;
144	sb->s_block_group_nr = 0;
145	if (fs->flags & EXT2_FLAG_SWAP_BYTES) {
146		retval = EXT2_ET_NO_MEMORY;
147		retval = ext2fs_get_mem(SUPERBLOCK_SIZE,
148					(void **) &super_shadow);
149		if (retval)
150			goto errout;
151		retval = ext2fs_get_mem((size_t)(fs->blocksize *
152						 fs->desc_blocks),
153					(void **) &group_shadow);
154		if (retval)
155			goto errout;
156		memset(group_shadow, 0, (size_t) fs->blocksize *
157		       fs->desc_blocks);
158
159		/* swap the superblock */
160		*super_shadow = *fs->super;
161		ext2fs_swap_super(super_shadow);
162		sb_shadow = (struct ext2fs_sb *) super_shadow;
163
164		/* swap the group descriptors */
165		for (j=0, s=fs->group_desc, t=group_shadow;
166		     j < fs->group_desc_count; j++, t++, s++) {
167			*t = *s;
168			ext2fs_swap_group_desc(t);
169		}
170	} else {
171		super_shadow = fs->super;
172		sb_shadow = (struct ext2fs_sb *) fs->super;
173		group_shadow = fs->group_desc;
174	}
175
176	/*
177	 * Write out master superblock.  This has to be done
178	 * separately, since it is located at a fixed location
179	 * (SUPERBLOCK_OFFSET).
180	 */
181	retval = write_primary_superblock(fs, super_shadow);
182	if (retval)
183		goto errout;
184
185	/*
186	 * Set the state of the FS to be non-valid.  (The state has
187	 * already been backed up earlier, and will be restored when
188	 * we exit.)
189	 */
190	fs->super->s_state &= ~EXT2_VALID_FS;
191	if (fs->flags & EXT2_FLAG_SWAP_BYTES) {
192		*super_shadow = *fs->super;
193		ext2fs_swap_super(super_shadow);
194	}
195
196	/*
197	 * Write out the master group descriptors, and the backup
198	 * superblocks and group descriptors.
199	 */
200	group_block = fs->super->s_first_data_block;
201	maxgroup = (fs->flags & EXT2_FLAG_MASTER_SB_ONLY) ? 1 :
202		fs->group_desc_count;
203	for (i = 0; i < maxgroup; i++) {
204		if (!ext2fs_bg_has_super(fs, i))
205			goto next_group;
206
207		sgrp = i;
208		if (sgrp > ((1 << 16) - 1))
209			sgrp = (1 << 16) - 1;
210		if (fs->flags & EXT2_FLAG_SWAP_BYTES)
211			sb_shadow->s_block_group_nr = ext2fs_swab16(sgrp);
212		else
213			sb->s_block_group_nr = sgrp;
214
215		if (i !=0 ) {
216			retval = io_channel_write_blk(fs->io, group_block,
217						      -SUPERBLOCK_SIZE,
218						      super_shadow);
219			if (retval)
220				goto errout;
221		}
222		group_ptr = (char *) group_shadow;
223		for (j=0; j < fs->desc_blocks; j++) {
224			retval = io_channel_write_blk(fs->io,
225						      group_block+1+j, 1,
226						      group_ptr);
227			if (retval)
228				goto errout;
229			group_ptr += fs->blocksize;
230		}
231	next_group:
232		group_block += EXT2_BLOCKS_PER_GROUP(fs->super);
233	}
234	sb->s_block_group_nr = 0;
235
236	/*
237	 * If the write_bitmaps() function is present, call it to
238	 * flush the bitmaps.  This is done this way so that a simple
239	 * program that doesn't mess with the bitmaps doesn't need to
240	 * drag in the bitmaps.c code.
241	 */
242	if (fs->write_bitmaps) {
243		retval = fs->write_bitmaps(fs);
244		if (retval)
245			goto errout;
246	}
247
248	/*
249	 * Flush the blocks out to disk
250	 */
251	retval = io_channel_flush(fs->io);
252errout:
253	fs->super->s_state = fs_state;
254	if (fs->flags & EXT2_FLAG_SWAP_BYTES) {
255		if (super_shadow)
256			ext2fs_free_mem((void **) &super_shadow);
257		if (group_shadow)
258			ext2fs_free_mem((void **) &group_shadow);
259	}
260	return retval;
261}
262
263errcode_t ext2fs_close(ext2_filsys fs)
264{
265	errcode_t	retval;
266
267	EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
268
269	if (fs->flags & EXT2_FLAG_DIRTY) {
270		retval = ext2fs_flush(fs);
271		if (retval)
272			return retval;
273	}
274	if (fs->write_bitmaps) {
275		retval = fs->write_bitmaps(fs);
276		if (retval)
277			return retval;
278	}
279	ext2fs_free(fs);
280	return 0;
281}
282
283