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 Library
8 * General Public License, version 2.
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
48 /*
49 * This function returns the location of the superblock, block group
50 * descriptors for a given block group. It currently returns the
51 * number of free blocks assuming that inode table and allocation
52 * bitmaps will be in the group. This is not necessarily the case
53 * when the flex_bg feature is enabled, so callers should take care!
54 * It was only really intended for use by mke2fs, and even there it's
55 * not that useful. In the future, when we redo this function for
56 * 64-bit block numbers, we should probably return the number of
57 * blocks used by the super block and group descriptors instead.
58 *
59 * See also the comment for ext2fs_reserve_super_and_bgd()
60 */
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)61 int ext2fs_super_and_bgd_loc(ext2_filsys fs,
62 dgrp_t group,
63 blk_t *ret_super_blk,
64 blk_t *ret_old_desc_blk,
65 blk_t *ret_new_desc_blk,
66 int *ret_meta_bg)
67 {
68 blk_t group_block, super_blk = 0, old_desc_blk = 0, new_desc_blk = 0;
69 unsigned int meta_bg, meta_bg_size;
70 blk_t numblocks, old_desc_blocks;
71 int has_super;
72
73 group_block = ext2fs_group_first_block(fs, group);
74
75 if (fs->super->s_feature_incompat & EXT2_FEATURE_INCOMPAT_META_BG)
76 old_desc_blocks = fs->super->s_first_meta_bg;
77 else
78 old_desc_blocks =
79 fs->desc_blocks + fs->super->s_reserved_gdt_blocks;
80
81 if (group == fs->group_desc_count-1) {
82 numblocks = (fs->super->s_blocks_count -
83 fs->super->s_first_data_block) %
84 fs->super->s_blocks_per_group;
85 if (!numblocks)
86 numblocks = fs->super->s_blocks_per_group;
87 } else
88 numblocks = fs->super->s_blocks_per_group;
89
90 has_super = ext2fs_bg_has_super(fs, group);
91
92 if (has_super) {
93 super_blk = group_block;
94 numblocks--;
95 }
96 meta_bg_size = EXT2_DESC_PER_BLOCK(fs->super);
97 meta_bg = group / meta_bg_size;
98
99 if (!(fs->super->s_feature_incompat & EXT2_FEATURE_INCOMPAT_META_BG) ||
100 (meta_bg < fs->super->s_first_meta_bg)) {
101 if (has_super) {
102 old_desc_blk = group_block + 1;
103 numblocks -= old_desc_blocks;
104 }
105 } else {
106 if (((group % meta_bg_size) == 0) ||
107 ((group % meta_bg_size) == 1) ||
108 ((group % meta_bg_size) == (meta_bg_size-1))) {
109 if (has_super)
110 has_super = 1;
111 new_desc_blk = group_block + has_super;
112 numblocks--;
113 }
114 }
115
116 numblocks -= 2 + fs->inode_blocks_per_group;
117
118 if (ret_super_blk)
119 *ret_super_blk = super_blk;
120 if (ret_old_desc_blk)
121 *ret_old_desc_blk = old_desc_blk;
122 if (ret_new_desc_blk)
123 *ret_new_desc_blk = new_desc_blk;
124 if (ret_meta_bg)
125 *ret_meta_bg = meta_bg;
126 return (numblocks);
127 }
128
129
130 /*
131 * This function forces out the primary superblock. We need to only
132 * write out those fields which we have changed, since if the
133 * filesystem is mounted, it may have changed some of the other
134 * fields.
135 *
136 * It takes as input a superblock which has already been byte swapped
137 * (if necessary).
138 *
139 */
write_primary_superblock(ext2_filsys fs,struct ext2_super_block * super)140 static errcode_t write_primary_superblock(ext2_filsys fs,
141 struct ext2_super_block *super)
142 {
143 __u16 *old_super, *new_super;
144 int check_idx, write_idx, size;
145 errcode_t retval;
146
147 if (!fs->io->manager->write_byte || !fs->orig_super) {
148 fallback:
149 io_channel_set_blksize(fs->io, SUPERBLOCK_OFFSET);
150 retval = io_channel_write_blk(fs->io, 1, -SUPERBLOCK_SIZE,
151 super);
152 io_channel_set_blksize(fs->io, fs->blocksize);
153 return retval;
154 }
155
156 old_super = (__u16 *) fs->orig_super;
157 new_super = (__u16 *) super;
158
159 for (check_idx = 0; check_idx < SUPERBLOCK_SIZE/2; check_idx++) {
160 if (old_super[check_idx] == new_super[check_idx])
161 continue;
162 write_idx = check_idx;
163 for (check_idx++; check_idx < SUPERBLOCK_SIZE/2; check_idx++)
164 if (old_super[check_idx] == new_super[check_idx])
165 break;
166 size = 2 * (check_idx - write_idx);
167 #if 0
168 printf("Writing %d bytes starting at %d\n",
169 size, write_idx*2);
170 #endif
171 retval = io_channel_write_byte(fs->io,
172 SUPERBLOCK_OFFSET + (2 * write_idx), size,
173 new_super + write_idx);
174 if (retval == EXT2_ET_UNIMPLEMENTED)
175 goto fallback;
176 if (retval)
177 return retval;
178 }
179 memcpy(fs->orig_super, super, SUPERBLOCK_SIZE);
180 return 0;
181 }
182
183
184 /*
185 * Updates the revision to EXT2_DYNAMIC_REV
186 */
ext2fs_update_dynamic_rev(ext2_filsys fs)187 void ext2fs_update_dynamic_rev(ext2_filsys fs)
188 {
189 struct ext2_super_block *sb = fs->super;
190
191 if (sb->s_rev_level > EXT2_GOOD_OLD_REV)
192 return;
193
194 sb->s_rev_level = EXT2_DYNAMIC_REV;
195 sb->s_first_ino = EXT2_GOOD_OLD_FIRST_INO;
196 sb->s_inode_size = EXT2_GOOD_OLD_INODE_SIZE;
197 /* s_uuid is handled by e2fsck already */
198 /* other fields should be left alone */
199 }
200
write_backup_super(ext2_filsys fs,dgrp_t group,blk_t group_block,struct ext2_super_block * super_shadow)201 static errcode_t write_backup_super(ext2_filsys fs, dgrp_t group,
202 blk_t group_block,
203 struct ext2_super_block *super_shadow)
204 {
205 dgrp_t sgrp = group;
206
207 if (sgrp > ((1 << 16) - 1))
208 sgrp = (1 << 16) - 1;
209 #ifdef WORDS_BIGENDIAN
210 super_shadow->s_block_group_nr = ext2fs_swab16(sgrp);
211 #else
212 fs->super->s_block_group_nr = sgrp;
213 #endif
214
215 return io_channel_write_blk(fs->io, group_block, -SUPERBLOCK_SIZE,
216 super_shadow);
217 }
218
219
ext2fs_flush(ext2_filsys fs)220 errcode_t ext2fs_flush(ext2_filsys fs)
221 {
222 dgrp_t i;
223 errcode_t retval;
224 unsigned long fs_state;
225 __u32 feature_incompat;
226 struct ext2_super_block *super_shadow = 0;
227 struct ext2_group_desc *group_shadow = 0;
228 #ifdef WORDS_BIGENDIAN
229 struct ext2_group_desc *s, *t;
230 dgrp_t j;
231 #endif
232 char *group_ptr;
233 int old_desc_blocks;
234
235 EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
236
237 fs_state = fs->super->s_state;
238 feature_incompat = fs->super->s_feature_incompat;
239
240 fs->super->s_wtime = fs->now ? fs->now : time(NULL);
241 fs->super->s_block_group_nr = 0;
242 #ifdef WORDS_BIGENDIAN
243 retval = EXT2_ET_NO_MEMORY;
244 retval = ext2fs_get_mem(SUPERBLOCK_SIZE, &super_shadow);
245 if (retval)
246 goto errout;
247 retval = ext2fs_get_array(fs->desc_blocks, fs->blocksize,
248 &group_shadow);
249 if (retval)
250 goto errout;
251 memset(group_shadow, 0, (size_t) fs->blocksize *
252 fs->desc_blocks);
253
254 /* swap the group descriptors */
255 for (j=0, s=fs->group_desc, t=group_shadow;
256 j < fs->group_desc_count; j++, t++, s++) {
257 *t = *s;
258 ext2fs_swap_group_desc(t);
259 }
260 #else
261 super_shadow = fs->super;
262 group_shadow = fs->group_desc;
263 #endif
264
265 /*
266 * Set the state of the FS to be non-valid. (The state has
267 * already been backed up earlier, and will be restored after
268 * we write out the backup superblocks.)
269 */
270 fs->super->s_state &= ~EXT2_VALID_FS;
271 fs->super->s_feature_incompat &= ~EXT3_FEATURE_INCOMPAT_RECOVER;
272 #ifdef WORDS_BIGENDIAN
273 *super_shadow = *fs->super;
274 ext2fs_swap_super(super_shadow);
275 #endif
276
277 /*
278 * If this is an external journal device, don't write out the
279 * block group descriptors or any of the backup superblocks
280 */
281 if (fs->super->s_feature_incompat &
282 EXT3_FEATURE_INCOMPAT_JOURNAL_DEV)
283 goto write_primary_superblock_only;
284
285 /*
286 * Write out the master group descriptors, and the backup
287 * superblocks and group descriptors.
288 */
289 group_ptr = (char *) group_shadow;
290 if (fs->super->s_feature_incompat & EXT2_FEATURE_INCOMPAT_META_BG)
291 old_desc_blocks = fs->super->s_first_meta_bg;
292 else
293 old_desc_blocks = fs->desc_blocks;
294
295 for (i = 0; i < fs->group_desc_count; i++) {
296 blk_t super_blk, old_desc_blk, new_desc_blk;
297 int meta_bg;
298
299 ext2fs_super_and_bgd_loc(fs, i, &super_blk, &old_desc_blk,
300 &new_desc_blk, &meta_bg);
301
302 if (!(fs->flags & EXT2_FLAG_MASTER_SB_ONLY) &&i && super_blk) {
303 retval = write_backup_super(fs, i, super_blk,
304 super_shadow);
305 if (retval)
306 goto errout;
307 }
308 if (fs->flags & EXT2_FLAG_SUPER_ONLY)
309 continue;
310 if ((old_desc_blk) &&
311 (!(fs->flags & EXT2_FLAG_MASTER_SB_ONLY) || (i == 0))) {
312 retval = io_channel_write_blk(fs->io,
313 old_desc_blk, old_desc_blocks, group_ptr);
314 if (retval)
315 goto errout;
316 }
317 if (new_desc_blk) {
318 retval = io_channel_write_blk(fs->io, new_desc_blk,
319 1, group_ptr + (meta_bg*fs->blocksize));
320 if (retval)
321 goto errout;
322 }
323 }
324
325 /*
326 * If the write_bitmaps() function is present, call it to
327 * flush the bitmaps. This is done this way so that a simple
328 * program that doesn't mess with the bitmaps doesn't need to
329 * drag in the bitmaps.c code.
330 */
331 if (fs->write_bitmaps) {
332 retval = fs->write_bitmaps(fs);
333 if (retval)
334 goto errout;
335 }
336
337 write_primary_superblock_only:
338 /*
339 * Write out master superblock. This has to be done
340 * separately, since it is located at a fixed location
341 * (SUPERBLOCK_OFFSET). We flush all other pending changes
342 * out to disk first, just to avoid a race condition with an
343 * insy-tinsy window....
344 */
345
346 fs->super->s_block_group_nr = 0;
347 fs->super->s_state = fs_state;
348 fs->super->s_feature_incompat = feature_incompat;
349 #ifdef WORDS_BIGENDIAN
350 *super_shadow = *fs->super;
351 ext2fs_swap_super(super_shadow);
352 #endif
353
354 retval = io_channel_flush(fs->io);
355 retval = write_primary_superblock(fs, super_shadow);
356 if (retval)
357 goto errout;
358
359 fs->flags &= ~EXT2_FLAG_DIRTY;
360
361 retval = io_channel_flush(fs->io);
362 errout:
363 fs->super->s_state = fs_state;
364 #ifdef WORDS_BIGENDIAN
365 if (super_shadow)
366 ext2fs_free_mem(&super_shadow);
367 if (group_shadow)
368 ext2fs_free_mem(&group_shadow);
369 #endif
370 return retval;
371 }
372
ext2fs_close(ext2_filsys fs)373 errcode_t ext2fs_close(ext2_filsys fs)
374 {
375 errcode_t retval;
376 int meta_blks;
377 io_stats stats = 0;
378
379 EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
380
381 if (fs->write_bitmaps) {
382 retval = fs->write_bitmaps(fs);
383 if (retval)
384 return retval;
385 }
386 if (fs->super->s_kbytes_written &&
387 fs->io->manager->get_stats)
388 fs->io->manager->get_stats(fs->io, &stats);
389 if (stats && stats->bytes_written && (fs->flags & EXT2_FLAG_RW)) {
390 fs->super->s_kbytes_written += stats->bytes_written >> 10;
391 meta_blks = fs->desc_blocks + 1;
392 if (!(fs->flags & EXT2_FLAG_SUPER_ONLY))
393 fs->super->s_kbytes_written += meta_blks /
394 (fs->blocksize / 1024);
395 if ((fs->flags & EXT2_FLAG_DIRTY) == 0)
396 fs->flags |= EXT2_FLAG_SUPER_ONLY | EXT2_FLAG_DIRTY;
397 }
398 if (fs->flags & EXT2_FLAG_DIRTY) {
399 retval = ext2fs_flush(fs);
400 if (retval)
401 return retval;
402 }
403 ext2fs_free(fs);
404 return 0;
405 }
406
407