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
test_root(int a,int b)22 static 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
ext2fs_bg_has_super(ext2_filsys fs,int group_block)35 int 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
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)48 int 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 */
write_primary_superblock(ext2_filsys fs,struct ext2_super_block * super)128 static 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 */
ext2fs_update_dynamic_rev(ext2_filsys fs)172 void 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
write_backup_super(ext2_filsys fs,dgrp_t group,blk_t group_block,struct ext2_super_block * super_shadow)186 static 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
ext2fs_flush(ext2_filsys fs)206 errcode_t ext2fs_flush(ext2_filsys fs)
207 {
208 dgrp_t i,j;
209 errcode_t retval;
210 unsigned long fs_state;
211 __u32 feature_incompat;
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 feature_incompat = fs->super->s_feature_incompat;
222
223 fs->super->s_wtime = fs->now ? fs->now : time(NULL);
224 fs->super->s_block_group_nr = 0;
225 #ifdef EXT2FS_ENABLE_SWAPFS
226 if (fs->flags & EXT2_FLAG_SWAP_BYTES) {
227 retval = EXT2_ET_NO_MEMORY;
228 retval = ext2fs_get_mem(SUPERBLOCK_SIZE, &super_shadow);
229 if (retval)
230 goto errout;
231 retval = ext2fs_get_array(fs->blocksize, 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 fs->super->s_feature_incompat &= ~EXT3_FEATURE_INCOMPAT_RECOVER;
260 #ifdef EXT2FS_ENABLE_SWAPFS
261 if (fs->flags & EXT2_FLAG_SWAP_BYTES) {
262 *super_shadow = *fs->super;
263 ext2fs_swap_super(super_shadow);
264 }
265 #endif
266
267 /*
268 * If this is an external journal device, don't write out the
269 * block group descriptors or any of the backup superblocks
270 */
271 if (fs->super->s_feature_incompat &
272 EXT3_FEATURE_INCOMPAT_JOURNAL_DEV)
273 goto write_primary_superblock_only;
274
275 /*
276 * Write out the master group descriptors, and the backup
277 * superblocks and group descriptors.
278 */
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
327 write_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 fs->super->s_feature_incompat = feature_incompat;
339 #ifdef EXT2FS_ENABLE_SWAPFS
340 if (fs->flags & EXT2_FLAG_SWAP_BYTES) {
341 *super_shadow = *fs->super;
342 ext2fs_swap_super(super_shadow);
343 }
344 #endif
345
346 retval = io_channel_flush(fs->io);
347 retval = write_primary_superblock(fs, super_shadow);
348 if (retval)
349 goto errout;
350
351 fs->flags &= ~EXT2_FLAG_DIRTY;
352
353 retval = io_channel_flush(fs->io);
354 errout:
355 fs->super->s_state = fs_state;
356 if (fs->flags & EXT2_FLAG_SWAP_BYTES) {
357 if (super_shadow)
358 ext2fs_free_mem(&super_shadow);
359 if (group_shadow)
360 ext2fs_free_mem(&group_shadow);
361 }
362 return retval;
363 }
364
ext2fs_close(ext2_filsys fs)365 errcode_t ext2fs_close(ext2_filsys fs)
366 {
367 errcode_t retval;
368
369 EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
370
371 if (fs->flags & EXT2_FLAG_DIRTY) {
372 retval = ext2fs_flush(fs);
373 if (retval)
374 return retval;
375 }
376 if (fs->write_bitmaps) {
377 retval = fs->write_bitmaps(fs);
378 if (retval)
379 return retval;
380 }
381 ext2fs_free(fs);
382 return 0;
383 }
384
385