source: branches/stable/mindi-busybox/e2fsprogs/ext2fs/closefs.c @ 821

Last change on this file since 821 was 821, checked in by Bruno Cornec, 14 years ago

Addition of busybox 1.2.1 as a mindi-busybox new package
This should avoid delivering binary files in mindi not built there (Fedora and Debian are quite serious about that)

File size: 9.3 KB
Line 
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#if BB_BIG_ENDIAN
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;
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    char    *group_ptr;
215    int old_desc_blocks;
216#if BB_BIG_ENDIAN
217    dgrp_t      j;
218    struct ext2_group_desc *s, *t;
219#endif
220
221    EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
222
223    fs_state = fs->super->s_state;
224
225    fs->super->s_wtime = time(NULL);
226    fs->super->s_block_group_nr = 0;
227#if BB_BIG_ENDIAN
228    if (fs->flags & EXT2_FLAG_SWAP_BYTES) {
229        retval = EXT2_ET_NO_MEMORY;
230        retval = ext2fs_get_mem(SUPERBLOCK_SIZE, &super_shadow);
231        if (retval)
232            goto errout;
233        retval = ext2fs_get_mem((size_t)(fs->blocksize *
234                         fs->desc_blocks),
235                    &group_shadow);
236        if (retval)
237            goto errout;
238        memset(group_shadow, 0, (size_t) fs->blocksize *
239               fs->desc_blocks);
240
241        /* swap the group descriptors */
242        for (j=0, s=fs->group_desc, t=group_shadow;
243             j < fs->group_desc_count; j++, t++, s++) {
244            *t = *s;
245            ext2fs_swap_group_desc(t);
246        }
247    } else {
248        super_shadow = fs->super;
249        group_shadow = fs->group_desc;
250    }
251#else
252    super_shadow = fs->super;
253    group_shadow = fs->group_desc;
254#endif
255
256    /*
257     * If this is an external journal device, don't write out the
258     * block group descriptors or any of the backup superblocks
259     */
260    if (fs->super->s_feature_incompat &
261        EXT3_FEATURE_INCOMPAT_JOURNAL_DEV)
262        goto write_primary_superblock_only;
263
264    /*
265     * Set the state of the FS to be non-valid.  (The state has
266     * already been backed up earlier, and will be restored after
267     * we write out the backup superblocks.)
268     */
269    fs->super->s_state &= ~EXT2_VALID_FS;
270#if BB_BIG_ENDIAN
271    if (fs->flags & EXT2_FLAG_SWAP_BYTES) {
272        *super_shadow = *fs->super;
273        ext2fs_swap_super(super_shadow);
274    }
275#endif
276
277    /*
278     * Write out the master group descriptors, and the backup
279     * superblocks and group descriptors.
280     */
281    group_block = fs->super->s_first_data_block;
282    group_ptr = (char *) group_shadow;
283    if (fs->super->s_feature_incompat & EXT2_FEATURE_INCOMPAT_META_BG)
284        old_desc_blocks = fs->super->s_first_meta_bg;
285    else
286        old_desc_blocks = fs->desc_blocks;
287
288    for (i = 0; i < fs->group_desc_count; i++) {
289        blk_t   super_blk, old_desc_blk, new_desc_blk;
290        int meta_bg;
291
292        ext2fs_super_and_bgd_loc(fs, i, &super_blk, &old_desc_blk,
293                     &new_desc_blk, &meta_bg);
294
295        if (!(fs->flags & EXT2_FLAG_MASTER_SB_ONLY) &&i && super_blk) {
296            retval = write_backup_super(fs, i, super_blk,
297                            super_shadow);
298            if (retval)
299                goto errout;
300        }
301        if (fs->flags & EXT2_FLAG_SUPER_ONLY)
302            continue;
303        if ((old_desc_blk) &&
304            (!(fs->flags & EXT2_FLAG_MASTER_SB_ONLY) || (i == 0))) {
305            retval = io_channel_write_blk(fs->io,
306                  old_desc_blk, old_desc_blocks, group_ptr);
307            if (retval)
308                goto errout;
309        }
310        if (new_desc_blk) {
311            retval = io_channel_write_blk(fs->io, new_desc_blk,
312                1, group_ptr + (meta_bg*fs->blocksize));
313            if (retval)
314                goto errout;
315        }
316    }
317    fs->super->s_block_group_nr = 0;
318    fs->super->s_state = fs_state;
319#if BB_BIG_ENDIAN
320    if (fs->flags & EXT2_FLAG_SWAP_BYTES) {
321        *super_shadow = *fs->super;
322        ext2fs_swap_super(super_shadow);
323    }
324#endif
325
326    /*
327     * If the write_bitmaps() function is present, call it to
328     * flush the bitmaps.  This is done this way so that a simple
329     * program that doesn't mess with the bitmaps doesn't need to
330     * drag in the bitmaps.c code.
331     */
332    if (fs->write_bitmaps) {
333        retval = fs->write_bitmaps(fs);
334        if (retval)
335            goto errout;
336    }
337
338write_primary_superblock_only:
339    /*
340     * Write out master superblock.  This has to be done
341     * separately, since it is located at a fixed location
342     * (SUPERBLOCK_OFFSET).  We flush all other pending changes
343     * out to disk first, just to avoid a race condition with an
344     * insy-tinsy window....
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);
354errout:
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
365errcode_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
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