Merge branch 'irq-fix' of git://www.modarm9.com/gitsrc/pub/people/ukleinek/linux...
[linux-2.6] / fs / ext4 / resize.c
1 /*
2  *  linux/fs/ext4/resize.c
3  *
4  * Support for resizing an ext4 filesystem while it is mounted.
5  *
6  * Copyright (C) 2001, 2002 Andreas Dilger <adilger@clusterfs.com>
7  *
8  * This could probably be made into a module, because it is not often in use.
9  */
10
11
12 #define EXT4FS_DEBUG
13
14 #include <linux/errno.h>
15 #include <linux/slab.h>
16
17 #include "ext4_jbd2.h"
18 #include "group.h"
19
20 #define outside(b, first, last) ((b) < (first) || (b) >= (last))
21 #define inside(b, first, last)  ((b) >= (first) && (b) < (last))
22
23 static int verify_group_input(struct super_block *sb,
24                               struct ext4_new_group_data *input)
25 {
26         struct ext4_sb_info *sbi = EXT4_SB(sb);
27         struct ext4_super_block *es = sbi->s_es;
28         ext4_fsblk_t start = ext4_blocks_count(es);
29         ext4_fsblk_t end = start + input->blocks_count;
30         ext4_group_t group = input->group;
31         ext4_fsblk_t itend = input->inode_table + sbi->s_itb_per_group;
32         unsigned overhead = ext4_bg_has_super(sb, group) ?
33                 (1 + ext4_bg_num_gdb(sb, group) +
34                  le16_to_cpu(es->s_reserved_gdt_blocks)) : 0;
35         ext4_fsblk_t metaend = start + overhead;
36         struct buffer_head *bh = NULL;
37         ext4_grpblk_t free_blocks_count, offset;
38         int err = -EINVAL;
39
40         input->free_blocks_count = free_blocks_count =
41                 input->blocks_count - 2 - overhead - sbi->s_itb_per_group;
42
43         if (test_opt(sb, DEBUG))
44                 printk(KERN_DEBUG "EXT4-fs: adding %s group %u: %u blocks "
45                        "(%d free, %u reserved)\n",
46                        ext4_bg_has_super(sb, input->group) ? "normal" :
47                        "no-super", input->group, input->blocks_count,
48                        free_blocks_count, input->reserved_blocks);
49
50         ext4_get_group_no_and_offset(sb, start, NULL, &offset);
51         if (group != sbi->s_groups_count)
52                 ext4_warning(sb, __func__,
53                              "Cannot add at group %u (only %lu groups)",
54                              input->group, sbi->s_groups_count);
55         else if (offset != 0)
56                         ext4_warning(sb, __func__, "Last group not full");
57         else if (input->reserved_blocks > input->blocks_count / 5)
58                 ext4_warning(sb, __func__, "Reserved blocks too high (%u)",
59                              input->reserved_blocks);
60         else if (free_blocks_count < 0)
61                 ext4_warning(sb, __func__, "Bad blocks count %u",
62                              input->blocks_count);
63         else if (!(bh = sb_bread(sb, end - 1)))
64                 ext4_warning(sb, __func__,
65                              "Cannot read last block (%llu)",
66                              end - 1);
67         else if (outside(input->block_bitmap, start, end))
68                 ext4_warning(sb, __func__,
69                              "Block bitmap not in group (block %llu)",
70                              (unsigned long long)input->block_bitmap);
71         else if (outside(input->inode_bitmap, start, end))
72                 ext4_warning(sb, __func__,
73                              "Inode bitmap not in group (block %llu)",
74                              (unsigned long long)input->inode_bitmap);
75         else if (outside(input->inode_table, start, end) ||
76                  outside(itend - 1, start, end))
77                 ext4_warning(sb, __func__,
78                              "Inode table not in group (blocks %llu-%llu)",
79                              (unsigned long long)input->inode_table, itend - 1);
80         else if (input->inode_bitmap == input->block_bitmap)
81                 ext4_warning(sb, __func__,
82                              "Block bitmap same as inode bitmap (%llu)",
83                              (unsigned long long)input->block_bitmap);
84         else if (inside(input->block_bitmap, input->inode_table, itend))
85                 ext4_warning(sb, __func__,
86                              "Block bitmap (%llu) in inode table (%llu-%llu)",
87                              (unsigned long long)input->block_bitmap,
88                              (unsigned long long)input->inode_table, itend - 1);
89         else if (inside(input->inode_bitmap, input->inode_table, itend))
90                 ext4_warning(sb, __func__,
91                              "Inode bitmap (%llu) in inode table (%llu-%llu)",
92                              (unsigned long long)input->inode_bitmap,
93                              (unsigned long long)input->inode_table, itend - 1);
94         else if (inside(input->block_bitmap, start, metaend))
95                 ext4_warning(sb, __func__,
96                              "Block bitmap (%llu) in GDT table"
97                              " (%llu-%llu)",
98                              (unsigned long long)input->block_bitmap,
99                              start, metaend - 1);
100         else if (inside(input->inode_bitmap, start, metaend))
101                 ext4_warning(sb, __func__,
102                              "Inode bitmap (%llu) in GDT table"
103                              " (%llu-%llu)",
104                              (unsigned long long)input->inode_bitmap,
105                              start, metaend - 1);
106         else if (inside(input->inode_table, start, metaend) ||
107                  inside(itend - 1, start, metaend))
108                 ext4_warning(sb, __func__,
109                              "Inode table (%llu-%llu) overlaps"
110                              "GDT table (%llu-%llu)",
111                              (unsigned long long)input->inode_table,
112                              itend - 1, start, metaend - 1);
113         else
114                 err = 0;
115         brelse(bh);
116
117         return err;
118 }
119
120 static struct buffer_head *bclean(handle_t *handle, struct super_block *sb,
121                                   ext4_fsblk_t blk)
122 {
123         struct buffer_head *bh;
124         int err;
125
126         bh = sb_getblk(sb, blk);
127         if (!bh)
128                 return ERR_PTR(-EIO);
129         if ((err = ext4_journal_get_write_access(handle, bh))) {
130                 brelse(bh);
131                 bh = ERR_PTR(err);
132         } else {
133                 lock_buffer(bh);
134                 memset(bh->b_data, 0, sb->s_blocksize);
135                 set_buffer_uptodate(bh);
136                 unlock_buffer(bh);
137         }
138
139         return bh;
140 }
141
142 /*
143  * If we have fewer than thresh credits, extend by EXT4_MAX_TRANS_DATA.
144  * If that fails, restart the transaction & regain write access for the
145  * buffer head which is used for block_bitmap modifications.
146  */
147 static int extend_or_restart_transaction(handle_t *handle, int thresh,
148                                          struct buffer_head *bh)
149 {
150         int err;
151
152         if (handle->h_buffer_credits >= thresh)
153                 return 0;
154
155         err = ext4_journal_extend(handle, EXT4_MAX_TRANS_DATA);
156         if (err < 0)
157                 return err;
158         if (err) {
159                 if ((err = ext4_journal_restart(handle, EXT4_MAX_TRANS_DATA)))
160                         return err;
161                 if ((err = ext4_journal_get_write_access(handle, bh)))
162                         return err;
163         }
164
165         return 0;
166 }
167
168 /*
169  * Set up the block and inode bitmaps, and the inode table for the new group.
170  * This doesn't need to be part of the main transaction, since we are only
171  * changing blocks outside the actual filesystem.  We still do journaling to
172  * ensure the recovery is correct in case of a failure just after resize.
173  * If any part of this fails, we simply abort the resize.
174  */
175 static int setup_new_group_blocks(struct super_block *sb,
176                                   struct ext4_new_group_data *input)
177 {
178         struct ext4_sb_info *sbi = EXT4_SB(sb);
179         ext4_fsblk_t start = ext4_group_first_block_no(sb, input->group);
180         int reserved_gdb = ext4_bg_has_super(sb, input->group) ?
181                 le16_to_cpu(sbi->s_es->s_reserved_gdt_blocks) : 0;
182         unsigned long gdblocks = ext4_bg_num_gdb(sb, input->group);
183         struct buffer_head *bh;
184         handle_t *handle;
185         ext4_fsblk_t block;
186         ext4_grpblk_t bit;
187         int i;
188         int err = 0, err2;
189
190         /* This transaction may be extended/restarted along the way */
191         handle = ext4_journal_start_sb(sb, EXT4_MAX_TRANS_DATA);
192
193         if (IS_ERR(handle))
194                 return PTR_ERR(handle);
195
196         lock_super(sb);
197         if (input->group != sbi->s_groups_count) {
198                 err = -EBUSY;
199                 goto exit_journal;
200         }
201
202         if (IS_ERR(bh = bclean(handle, sb, input->block_bitmap))) {
203                 err = PTR_ERR(bh);
204                 goto exit_journal;
205         }
206
207         if (ext4_bg_has_super(sb, input->group)) {
208                 ext4_debug("mark backup superblock %#04llx (+0)\n", start);
209                 ext4_set_bit(0, bh->b_data);
210         }
211
212         /* Copy all of the GDT blocks into the backup in this group */
213         for (i = 0, bit = 1, block = start + 1;
214              i < gdblocks; i++, block++, bit++) {
215                 struct buffer_head *gdb;
216
217                 ext4_debug("update backup group %#04llx (+%d)\n", block, bit);
218
219                 if ((err = extend_or_restart_transaction(handle, 1, bh)))
220                         goto exit_bh;
221
222                 gdb = sb_getblk(sb, block);
223                 if (!gdb) {
224                         err = -EIO;
225                         goto exit_bh;
226                 }
227                 if ((err = ext4_journal_get_write_access(handle, gdb))) {
228                         brelse(gdb);
229                         goto exit_bh;
230                 }
231                 lock_buffer(gdb);
232                 memcpy(gdb->b_data, sbi->s_group_desc[i]->b_data, gdb->b_size);
233                 set_buffer_uptodate(gdb);
234                 unlock_buffer(gdb);
235                 ext4_journal_dirty_metadata(handle, gdb);
236                 ext4_set_bit(bit, bh->b_data);
237                 brelse(gdb);
238         }
239
240         /* Zero out all of the reserved backup group descriptor table blocks */
241         for (i = 0, bit = gdblocks + 1, block = start + bit;
242              i < reserved_gdb; i++, block++, bit++) {
243                 struct buffer_head *gdb;
244
245                 ext4_debug("clear reserved block %#04llx (+%d)\n", block, bit);
246
247                 if ((err = extend_or_restart_transaction(handle, 1, bh)))
248                         goto exit_bh;
249
250                 if (IS_ERR(gdb = bclean(handle, sb, block))) {
251                         err = PTR_ERR(bh);
252                         goto exit_bh;
253                 }
254                 ext4_journal_dirty_metadata(handle, gdb);
255                 ext4_set_bit(bit, bh->b_data);
256                 brelse(gdb);
257         }
258         ext4_debug("mark block bitmap %#04llx (+%llu)\n", input->block_bitmap,
259                    input->block_bitmap - start);
260         ext4_set_bit(input->block_bitmap - start, bh->b_data);
261         ext4_debug("mark inode bitmap %#04llx (+%llu)\n", input->inode_bitmap,
262                    input->inode_bitmap - start);
263         ext4_set_bit(input->inode_bitmap - start, bh->b_data);
264
265         /* Zero out all of the inode table blocks */
266         for (i = 0, block = input->inode_table, bit = block - start;
267              i < sbi->s_itb_per_group; i++, bit++, block++) {
268                 struct buffer_head *it;
269
270                 ext4_debug("clear inode block %#04llx (+%d)\n", block, bit);
271
272                 if ((err = extend_or_restart_transaction(handle, 1, bh)))
273                         goto exit_bh;
274
275                 if (IS_ERR(it = bclean(handle, sb, block))) {
276                         err = PTR_ERR(it);
277                         goto exit_bh;
278                 }
279                 ext4_journal_dirty_metadata(handle, it);
280                 brelse(it);
281                 ext4_set_bit(bit, bh->b_data);
282         }
283
284         if ((err = extend_or_restart_transaction(handle, 2, bh)))
285                 goto exit_bh;
286
287         mark_bitmap_end(input->blocks_count, EXT4_BLOCKS_PER_GROUP(sb),
288                         bh->b_data);
289         ext4_journal_dirty_metadata(handle, bh);
290         brelse(bh);
291
292         /* Mark unused entries in inode bitmap used */
293         ext4_debug("clear inode bitmap %#04llx (+%llu)\n",
294                    input->inode_bitmap, input->inode_bitmap - start);
295         if (IS_ERR(bh = bclean(handle, sb, input->inode_bitmap))) {
296                 err = PTR_ERR(bh);
297                 goto exit_journal;
298         }
299
300         mark_bitmap_end(EXT4_INODES_PER_GROUP(sb), EXT4_BLOCKS_PER_GROUP(sb),
301                         bh->b_data);
302         ext4_journal_dirty_metadata(handle, bh);
303 exit_bh:
304         brelse(bh);
305
306 exit_journal:
307         unlock_super(sb);
308         if ((err2 = ext4_journal_stop(handle)) && !err)
309                 err = err2;
310
311         return err;
312 }
313
314 /*
315  * Iterate through the groups which hold BACKUP superblock/GDT copies in an
316  * ext4 filesystem.  The counters should be initialized to 1, 5, and 7 before
317  * calling this for the first time.  In a sparse filesystem it will be the
318  * sequence of powers of 3, 5, and 7: 1, 3, 5, 7, 9, 25, 27, 49, 81, ...
319  * For a non-sparse filesystem it will be every group: 1, 2, 3, 4, ...
320  */
321 static unsigned ext4_list_backups(struct super_block *sb, unsigned *three,
322                                   unsigned *five, unsigned *seven)
323 {
324         unsigned *min = three;
325         int mult = 3;
326         unsigned ret;
327
328         if (!EXT4_HAS_RO_COMPAT_FEATURE(sb,
329                                         EXT4_FEATURE_RO_COMPAT_SPARSE_SUPER)) {
330                 ret = *min;
331                 *min += 1;
332                 return ret;
333         }
334
335         if (*five < *min) {
336                 min = five;
337                 mult = 5;
338         }
339         if (*seven < *min) {
340                 min = seven;
341                 mult = 7;
342         }
343
344         ret = *min;
345         *min *= mult;
346
347         return ret;
348 }
349
350 /*
351  * Check that all of the backup GDT blocks are held in the primary GDT block.
352  * It is assumed that they are stored in group order.  Returns the number of
353  * groups in current filesystem that have BACKUPS, or -ve error code.
354  */
355 static int verify_reserved_gdb(struct super_block *sb,
356                                struct buffer_head *primary)
357 {
358         const ext4_fsblk_t blk = primary->b_blocknr;
359         const ext4_group_t end = EXT4_SB(sb)->s_groups_count;
360         unsigned three = 1;
361         unsigned five = 5;
362         unsigned seven = 7;
363         unsigned grp;
364         __le32 *p = (__le32 *)primary->b_data;
365         int gdbackups = 0;
366
367         while ((grp = ext4_list_backups(sb, &three, &five, &seven)) < end) {
368                 if (le32_to_cpu(*p++) !=
369                     grp * EXT4_BLOCKS_PER_GROUP(sb) + blk){
370                         ext4_warning(sb, __func__,
371                                      "reserved GDT %llu"
372                                      " missing grp %d (%llu)",
373                                      blk, grp,
374                                      grp *
375                                      (ext4_fsblk_t)EXT4_BLOCKS_PER_GROUP(sb) +
376                                      blk);
377                         return -EINVAL;
378                 }
379                 if (++gdbackups > EXT4_ADDR_PER_BLOCK(sb))
380                         return -EFBIG;
381         }
382
383         return gdbackups;
384 }
385
386 /*
387  * Called when we need to bring a reserved group descriptor table block into
388  * use from the resize inode.  The primary copy of the new GDT block currently
389  * is an indirect block (under the double indirect block in the resize inode).
390  * The new backup GDT blocks will be stored as leaf blocks in this indirect
391  * block, in group order.  Even though we know all the block numbers we need,
392  * we check to ensure that the resize inode has actually reserved these blocks.
393  *
394  * Don't need to update the block bitmaps because the blocks are still in use.
395  *
396  * We get all of the error cases out of the way, so that we are sure to not
397  * fail once we start modifying the data on disk, because JBD has no rollback.
398  */
399 static int add_new_gdb(handle_t *handle, struct inode *inode,
400                        struct ext4_new_group_data *input,
401                        struct buffer_head **primary)
402 {
403         struct super_block *sb = inode->i_sb;
404         struct ext4_super_block *es = EXT4_SB(sb)->s_es;
405         unsigned long gdb_num = input->group / EXT4_DESC_PER_BLOCK(sb);
406         ext4_fsblk_t gdblock = EXT4_SB(sb)->s_sbh->b_blocknr + 1 + gdb_num;
407         struct buffer_head **o_group_desc, **n_group_desc;
408         struct buffer_head *dind;
409         int gdbackups;
410         struct ext4_iloc iloc;
411         __le32 *data;
412         int err;
413
414         if (test_opt(sb, DEBUG))
415                 printk(KERN_DEBUG
416                        "EXT4-fs: ext4_add_new_gdb: adding group block %lu\n",
417                        gdb_num);
418
419         /*
420          * If we are not using the primary superblock/GDT copy don't resize,
421          * because the user tools have no way of handling this.  Probably a
422          * bad time to do it anyways.
423          */
424         if (EXT4_SB(sb)->s_sbh->b_blocknr !=
425             le32_to_cpu(EXT4_SB(sb)->s_es->s_first_data_block)) {
426                 ext4_warning(sb, __func__,
427                         "won't resize using backup superblock at %llu",
428                         (unsigned long long)EXT4_SB(sb)->s_sbh->b_blocknr);
429                 return -EPERM;
430         }
431
432         *primary = sb_bread(sb, gdblock);
433         if (!*primary)
434                 return -EIO;
435
436         if ((gdbackups = verify_reserved_gdb(sb, *primary)) < 0) {
437                 err = gdbackups;
438                 goto exit_bh;
439         }
440
441         data = EXT4_I(inode)->i_data + EXT4_DIND_BLOCK;
442         dind = sb_bread(sb, le32_to_cpu(*data));
443         if (!dind) {
444                 err = -EIO;
445                 goto exit_bh;
446         }
447
448         data = (__le32 *)dind->b_data;
449         if (le32_to_cpu(data[gdb_num % EXT4_ADDR_PER_BLOCK(sb)]) != gdblock) {
450                 ext4_warning(sb, __func__,
451                              "new group %u GDT block %llu not reserved",
452                              input->group, gdblock);
453                 err = -EINVAL;
454                 goto exit_dind;
455         }
456
457         if ((err = ext4_journal_get_write_access(handle, EXT4_SB(sb)->s_sbh)))
458                 goto exit_dind;
459
460         if ((err = ext4_journal_get_write_access(handle, *primary)))
461                 goto exit_sbh;
462
463         if ((err = ext4_journal_get_write_access(handle, dind)))
464                 goto exit_primary;
465
466         /* ext4_reserve_inode_write() gets a reference on the iloc */
467         if ((err = ext4_reserve_inode_write(handle, inode, &iloc)))
468                 goto exit_dindj;
469
470         n_group_desc = kmalloc((gdb_num + 1) * sizeof(struct buffer_head *),
471                         GFP_NOFS);
472         if (!n_group_desc) {
473                 err = -ENOMEM;
474                 ext4_warning(sb, __func__,
475                               "not enough memory for %lu groups", gdb_num + 1);
476                 goto exit_inode;
477         }
478
479         /*
480          * Finally, we have all of the possible failures behind us...
481          *
482          * Remove new GDT block from inode double-indirect block and clear out
483          * the new GDT block for use (which also "frees" the backup GDT blocks
484          * from the reserved inode).  We don't need to change the bitmaps for
485          * these blocks, because they are marked as in-use from being in the
486          * reserved inode, and will become GDT blocks (primary and backup).
487          */
488         data[gdb_num % EXT4_ADDR_PER_BLOCK(sb)] = 0;
489         ext4_journal_dirty_metadata(handle, dind);
490         brelse(dind);
491         inode->i_blocks -= (gdbackups + 1) * sb->s_blocksize >> 9;
492         ext4_mark_iloc_dirty(handle, inode, &iloc);
493         memset((*primary)->b_data, 0, sb->s_blocksize);
494         ext4_journal_dirty_metadata(handle, *primary);
495
496         o_group_desc = EXT4_SB(sb)->s_group_desc;
497         memcpy(n_group_desc, o_group_desc,
498                EXT4_SB(sb)->s_gdb_count * sizeof(struct buffer_head *));
499         n_group_desc[gdb_num] = *primary;
500         EXT4_SB(sb)->s_group_desc = n_group_desc;
501         EXT4_SB(sb)->s_gdb_count++;
502         kfree(o_group_desc);
503
504         le16_add_cpu(&es->s_reserved_gdt_blocks, -1);
505         ext4_journal_dirty_metadata(handle, EXT4_SB(sb)->s_sbh);
506
507         return 0;
508
509 exit_inode:
510         //ext4_journal_release_buffer(handle, iloc.bh);
511         brelse(iloc.bh);
512 exit_dindj:
513         //ext4_journal_release_buffer(handle, dind);
514 exit_primary:
515         //ext4_journal_release_buffer(handle, *primary);
516 exit_sbh:
517         //ext4_journal_release_buffer(handle, *primary);
518 exit_dind:
519         brelse(dind);
520 exit_bh:
521         brelse(*primary);
522
523         ext4_debug("leaving with error %d\n", err);
524         return err;
525 }
526
527 /*
528  * Called when we are adding a new group which has a backup copy of each of
529  * the GDT blocks (i.e. sparse group) and there are reserved GDT blocks.
530  * We need to add these reserved backup GDT blocks to the resize inode, so
531  * that they are kept for future resizing and not allocated to files.
532  *
533  * Each reserved backup GDT block will go into a different indirect block.
534  * The indirect blocks are actually the primary reserved GDT blocks,
535  * so we know in advance what their block numbers are.  We only get the
536  * double-indirect block to verify it is pointing to the primary reserved
537  * GDT blocks so we don't overwrite a data block by accident.  The reserved
538  * backup GDT blocks are stored in their reserved primary GDT block.
539  */
540 static int reserve_backup_gdb(handle_t *handle, struct inode *inode,
541                               struct ext4_new_group_data *input)
542 {
543         struct super_block *sb = inode->i_sb;
544         int reserved_gdb =le16_to_cpu(EXT4_SB(sb)->s_es->s_reserved_gdt_blocks);
545         struct buffer_head **primary;
546         struct buffer_head *dind;
547         struct ext4_iloc iloc;
548         ext4_fsblk_t blk;
549         __le32 *data, *end;
550         int gdbackups = 0;
551         int res, i;
552         int err;
553
554         primary = kmalloc(reserved_gdb * sizeof(*primary), GFP_NOFS);
555         if (!primary)
556                 return -ENOMEM;
557
558         data = EXT4_I(inode)->i_data + EXT4_DIND_BLOCK;
559         dind = sb_bread(sb, le32_to_cpu(*data));
560         if (!dind) {
561                 err = -EIO;
562                 goto exit_free;
563         }
564
565         blk = EXT4_SB(sb)->s_sbh->b_blocknr + 1 + EXT4_SB(sb)->s_gdb_count;
566         data = (__le32 *)dind->b_data + EXT4_SB(sb)->s_gdb_count;
567         end = (__le32 *)dind->b_data + EXT4_ADDR_PER_BLOCK(sb);
568
569         /* Get each reserved primary GDT block and verify it holds backups */
570         for (res = 0; res < reserved_gdb; res++, blk++) {
571                 if (le32_to_cpu(*data) != blk) {
572                         ext4_warning(sb, __func__,
573                                      "reserved block %llu"
574                                      " not at offset %ld",
575                                      blk,
576                                      (long)(data - (__le32 *)dind->b_data));
577                         err = -EINVAL;
578                         goto exit_bh;
579                 }
580                 primary[res] = sb_bread(sb, blk);
581                 if (!primary[res]) {
582                         err = -EIO;
583                         goto exit_bh;
584                 }
585                 if ((gdbackups = verify_reserved_gdb(sb, primary[res])) < 0) {
586                         brelse(primary[res]);
587                         err = gdbackups;
588                         goto exit_bh;
589                 }
590                 if (++data >= end)
591                         data = (__le32 *)dind->b_data;
592         }
593
594         for (i = 0; i < reserved_gdb; i++) {
595                 if ((err = ext4_journal_get_write_access(handle, primary[i]))) {
596                         /*
597                         int j;
598                         for (j = 0; j < i; j++)
599                                 ext4_journal_release_buffer(handle, primary[j]);
600                          */
601                         goto exit_bh;
602                 }
603         }
604
605         if ((err = ext4_reserve_inode_write(handle, inode, &iloc)))
606                 goto exit_bh;
607
608         /*
609          * Finally we can add each of the reserved backup GDT blocks from
610          * the new group to its reserved primary GDT block.
611          */
612         blk = input->group * EXT4_BLOCKS_PER_GROUP(sb);
613         for (i = 0; i < reserved_gdb; i++) {
614                 int err2;
615                 data = (__le32 *)primary[i]->b_data;
616                 /* printk("reserving backup %lu[%u] = %lu\n",
617                        primary[i]->b_blocknr, gdbackups,
618                        blk + primary[i]->b_blocknr); */
619                 data[gdbackups] = cpu_to_le32(blk + primary[i]->b_blocknr);
620                 err2 = ext4_journal_dirty_metadata(handle, primary[i]);
621                 if (!err)
622                         err = err2;
623         }
624         inode->i_blocks += reserved_gdb * sb->s_blocksize >> 9;
625         ext4_mark_iloc_dirty(handle, inode, &iloc);
626
627 exit_bh:
628         while (--res >= 0)
629                 brelse(primary[res]);
630         brelse(dind);
631
632 exit_free:
633         kfree(primary);
634
635         return err;
636 }
637
638 /*
639  * Update the backup copies of the ext4 metadata.  These don't need to be part
640  * of the main resize transaction, because e2fsck will re-write them if there
641  * is a problem (basically only OOM will cause a problem).  However, we
642  * _should_ update the backups if possible, in case the primary gets trashed
643  * for some reason and we need to run e2fsck from a backup superblock.  The
644  * important part is that the new block and inode counts are in the backup
645  * superblocks, and the location of the new group metadata in the GDT backups.
646  *
647  * We do not need lock_super() for this, because these blocks are not
648  * otherwise touched by the filesystem code when it is mounted.  We don't
649  * need to worry about last changing from sbi->s_groups_count, because the
650  * worst that can happen is that we do not copy the full number of backups
651  * at this time.  The resize which changed s_groups_count will backup again.
652  */
653 static void update_backups(struct super_block *sb,
654                            int blk_off, char *data, int size)
655 {
656         struct ext4_sb_info *sbi = EXT4_SB(sb);
657         const ext4_group_t last = sbi->s_groups_count;
658         const int bpg = EXT4_BLOCKS_PER_GROUP(sb);
659         unsigned three = 1;
660         unsigned five = 5;
661         unsigned seven = 7;
662         ext4_group_t group;
663         int rest = sb->s_blocksize - size;
664         handle_t *handle;
665         int err = 0, err2;
666
667         handle = ext4_journal_start_sb(sb, EXT4_MAX_TRANS_DATA);
668         if (IS_ERR(handle)) {
669                 group = 1;
670                 err = PTR_ERR(handle);
671                 goto exit_err;
672         }
673
674         while ((group = ext4_list_backups(sb, &three, &five, &seven)) < last) {
675                 struct buffer_head *bh;
676
677                 /* Out of journal space, and can't get more - abort - so sad */
678                 if (handle->h_buffer_credits == 0 &&
679                     ext4_journal_extend(handle, EXT4_MAX_TRANS_DATA) &&
680                     (err = ext4_journal_restart(handle, EXT4_MAX_TRANS_DATA)))
681                         break;
682
683                 bh = sb_getblk(sb, group * bpg + blk_off);
684                 if (!bh) {
685                         err = -EIO;
686                         break;
687                 }
688                 ext4_debug("update metadata backup %#04lx\n",
689                           (unsigned long)bh->b_blocknr);
690                 if ((err = ext4_journal_get_write_access(handle, bh)))
691                         break;
692                 lock_buffer(bh);
693                 memcpy(bh->b_data, data, size);
694                 if (rest)
695                         memset(bh->b_data + size, 0, rest);
696                 set_buffer_uptodate(bh);
697                 unlock_buffer(bh);
698                 ext4_journal_dirty_metadata(handle, bh);
699                 brelse(bh);
700         }
701         if ((err2 = ext4_journal_stop(handle)) && !err)
702                 err = err2;
703
704         /*
705          * Ugh! Need to have e2fsck write the backup copies.  It is too
706          * late to revert the resize, we shouldn't fail just because of
707          * the backup copies (they are only needed in case of corruption).
708          *
709          * However, if we got here we have a journal problem too, so we
710          * can't really start a transaction to mark the superblock.
711          * Chicken out and just set the flag on the hope it will be written
712          * to disk, and if not - we will simply wait until next fsck.
713          */
714 exit_err:
715         if (err) {
716                 ext4_warning(sb, __func__,
717                              "can't update backup for group %lu (err %d), "
718                              "forcing fsck on next reboot", group, err);
719                 sbi->s_mount_state &= ~EXT4_VALID_FS;
720                 sbi->s_es->s_state &= cpu_to_le16(~EXT4_VALID_FS);
721                 mark_buffer_dirty(sbi->s_sbh);
722         }
723 }
724
725 /* Add group descriptor data to an existing or new group descriptor block.
726  * Ensure we handle all possible error conditions _before_ we start modifying
727  * the filesystem, because we cannot abort the transaction and not have it
728  * write the data to disk.
729  *
730  * If we are on a GDT block boundary, we need to get the reserved GDT block.
731  * Otherwise, we may need to add backup GDT blocks for a sparse group.
732  *
733  * We only need to hold the superblock lock while we are actually adding
734  * in the new group's counts to the superblock.  Prior to that we have
735  * not really "added" the group at all.  We re-check that we are still
736  * adding in the last group in case things have changed since verifying.
737  */
738 int ext4_group_add(struct super_block *sb, struct ext4_new_group_data *input)
739 {
740         struct ext4_sb_info *sbi = EXT4_SB(sb);
741         struct ext4_super_block *es = sbi->s_es;
742         int reserved_gdb = ext4_bg_has_super(sb, input->group) ?
743                 le16_to_cpu(es->s_reserved_gdt_blocks) : 0;
744         struct buffer_head *primary = NULL;
745         struct ext4_group_desc *gdp;
746         struct inode *inode = NULL;
747         handle_t *handle;
748         int gdb_off, gdb_num;
749         int err, err2;
750
751         gdb_num = input->group / EXT4_DESC_PER_BLOCK(sb);
752         gdb_off = input->group % EXT4_DESC_PER_BLOCK(sb);
753
754         if (gdb_off == 0 && !EXT4_HAS_RO_COMPAT_FEATURE(sb,
755                                         EXT4_FEATURE_RO_COMPAT_SPARSE_SUPER)) {
756                 ext4_warning(sb, __func__,
757                              "Can't resize non-sparse filesystem further");
758                 return -EPERM;
759         }
760
761         if (ext4_blocks_count(es) + input->blocks_count <
762             ext4_blocks_count(es)) {
763                 ext4_warning(sb, __func__, "blocks_count overflow\n");
764                 return -EINVAL;
765         }
766
767         if (le32_to_cpu(es->s_inodes_count) + EXT4_INODES_PER_GROUP(sb) <
768             le32_to_cpu(es->s_inodes_count)) {
769                 ext4_warning(sb, __func__, "inodes_count overflow\n");
770                 return -EINVAL;
771         }
772
773         if (reserved_gdb || gdb_off == 0) {
774                 if (!EXT4_HAS_COMPAT_FEATURE(sb,
775                                              EXT4_FEATURE_COMPAT_RESIZE_INODE)){
776                         ext4_warning(sb, __func__,
777                                      "No reserved GDT blocks, can't resize");
778                         return -EPERM;
779                 }
780                 inode = ext4_iget(sb, EXT4_RESIZE_INO);
781                 if (IS_ERR(inode)) {
782                         ext4_warning(sb, __func__,
783                                      "Error opening resize inode");
784                         return PTR_ERR(inode);
785                 }
786         }
787
788         if ((err = verify_group_input(sb, input)))
789                 goto exit_put;
790
791         if ((err = setup_new_group_blocks(sb, input)))
792                 goto exit_put;
793
794         /*
795          * We will always be modifying at least the superblock and a GDT
796          * block.  If we are adding a group past the last current GDT block,
797          * we will also modify the inode and the dindirect block.  If we
798          * are adding a group with superblock/GDT backups  we will also
799          * modify each of the reserved GDT dindirect blocks.
800          */
801         handle = ext4_journal_start_sb(sb,
802                                        ext4_bg_has_super(sb, input->group) ?
803                                        3 + reserved_gdb : 4);
804         if (IS_ERR(handle)) {
805                 err = PTR_ERR(handle);
806                 goto exit_put;
807         }
808
809         lock_super(sb);
810         if (input->group != sbi->s_groups_count) {
811                 ext4_warning(sb, __func__,
812                              "multiple resizers run on filesystem!");
813                 err = -EBUSY;
814                 goto exit_journal;
815         }
816
817         if ((err = ext4_journal_get_write_access(handle, sbi->s_sbh)))
818                 goto exit_journal;
819
820         /*
821          * We will only either add reserved group blocks to a backup group
822          * or remove reserved blocks for the first group in a new group block.
823          * Doing both would be mean more complex code, and sane people don't
824          * use non-sparse filesystems anymore.  This is already checked above.
825          */
826         if (gdb_off) {
827                 primary = sbi->s_group_desc[gdb_num];
828                 if ((err = ext4_journal_get_write_access(handle, primary)))
829                         goto exit_journal;
830
831                 if (reserved_gdb && ext4_bg_num_gdb(sb, input->group) &&
832                     (err = reserve_backup_gdb(handle, inode, input)))
833                         goto exit_journal;
834         } else if ((err = add_new_gdb(handle, inode, input, &primary)))
835                 goto exit_journal;
836
837         /*
838          * OK, now we've set up the new group.  Time to make it active.
839          *
840          * Current kernels don't lock all allocations via lock_super(),
841          * so we have to be safe wrt. concurrent accesses the group
842          * data.  So we need to be careful to set all of the relevant
843          * group descriptor data etc. *before* we enable the group.
844          *
845          * The key field here is sbi->s_groups_count: as long as
846          * that retains its old value, nobody is going to access the new
847          * group.
848          *
849          * So first we update all the descriptor metadata for the new
850          * group; then we update the total disk blocks count; then we
851          * update the groups count to enable the group; then finally we
852          * update the free space counts so that the system can start
853          * using the new disk blocks.
854          */
855
856         /* Update group descriptor block for new group */
857         gdp = (struct ext4_group_desc *)primary->b_data + gdb_off;
858
859         ext4_block_bitmap_set(sb, gdp, input->block_bitmap); /* LV FIXME */
860         ext4_inode_bitmap_set(sb, gdp, input->inode_bitmap); /* LV FIXME */
861         ext4_inode_table_set(sb, gdp, input->inode_table); /* LV FIXME */
862         gdp->bg_free_blocks_count = cpu_to_le16(input->free_blocks_count);
863         gdp->bg_free_inodes_count = cpu_to_le16(EXT4_INODES_PER_GROUP(sb));
864         gdp->bg_checksum = ext4_group_desc_csum(sbi, input->group, gdp);
865
866         /*
867          * Make the new blocks and inodes valid next.  We do this before
868          * increasing the group count so that once the group is enabled,
869          * all of its blocks and inodes are already valid.
870          *
871          * We always allocate group-by-group, then block-by-block or
872          * inode-by-inode within a group, so enabling these
873          * blocks/inodes before the group is live won't actually let us
874          * allocate the new space yet.
875          */
876         ext4_blocks_count_set(es, ext4_blocks_count(es) +
877                 input->blocks_count);
878         le32_add_cpu(&es->s_inodes_count, EXT4_INODES_PER_GROUP(sb));
879
880         /*
881          * We need to protect s_groups_count against other CPUs seeing
882          * inconsistent state in the superblock.
883          *
884          * The precise rules we use are:
885          *
886          * * Writers of s_groups_count *must* hold lock_super
887          * AND
888          * * Writers must perform a smp_wmb() after updating all dependent
889          *   data and before modifying the groups count
890          *
891          * * Readers must hold lock_super() over the access
892          * OR
893          * * Readers must perform an smp_rmb() after reading the groups count
894          *   and before reading any dependent data.
895          *
896          * NB. These rules can be relaxed when checking the group count
897          * while freeing data, as we can only allocate from a block
898          * group after serialising against the group count, and we can
899          * only then free after serialising in turn against that
900          * allocation.
901          */
902         smp_wmb();
903
904         /* Update the global fs size fields */
905         sbi->s_groups_count++;
906
907         ext4_journal_dirty_metadata(handle, primary);
908
909         /* Update the reserved block counts only once the new group is
910          * active. */
911         ext4_r_blocks_count_set(es, ext4_r_blocks_count(es) +
912                 input->reserved_blocks);
913
914         /* Update the free space counts */
915         percpu_counter_add(&sbi->s_freeblocks_counter,
916                            input->free_blocks_count);
917         percpu_counter_add(&sbi->s_freeinodes_counter,
918                            EXT4_INODES_PER_GROUP(sb));
919
920         ext4_journal_dirty_metadata(handle, sbi->s_sbh);
921         sb->s_dirt = 1;
922
923 exit_journal:
924         unlock_super(sb);
925         if ((err2 = ext4_journal_stop(handle)) && !err)
926                 err = err2;
927         if (!err) {
928                 update_backups(sb, sbi->s_sbh->b_blocknr, (char *)es,
929                                sizeof(struct ext4_super_block));
930                 update_backups(sb, primary->b_blocknr, primary->b_data,
931                                primary->b_size);
932         }
933 exit_put:
934         iput(inode);
935         return err;
936 } /* ext4_group_add */
937
938 /* Extend the filesystem to the new number of blocks specified.  This entry
939  * point is only used to extend the current filesystem to the end of the last
940  * existing group.  It can be accessed via ioctl, or by "remount,resize=<size>"
941  * for emergencies (because it has no dependencies on reserved blocks).
942  *
943  * If we _really_ wanted, we could use default values to call ext4_group_add()
944  * allow the "remount" trick to work for arbitrary resizing, assuming enough
945  * GDT blocks are reserved to grow to the desired size.
946  */
947 int ext4_group_extend(struct super_block *sb, struct ext4_super_block *es,
948                       ext4_fsblk_t n_blocks_count)
949 {
950         ext4_fsblk_t o_blocks_count;
951         ext4_group_t o_groups_count;
952         ext4_grpblk_t last;
953         ext4_grpblk_t add;
954         struct buffer_head * bh;
955         handle_t *handle;
956         int err;
957         unsigned long freed_blocks;
958
959         /* We don't need to worry about locking wrt other resizers just
960          * yet: we're going to revalidate es->s_blocks_count after
961          * taking lock_super() below. */
962         o_blocks_count = ext4_blocks_count(es);
963         o_groups_count = EXT4_SB(sb)->s_groups_count;
964
965         if (test_opt(sb, DEBUG))
966                 printk(KERN_DEBUG "EXT4-fs: extending last group from %llu uto %llu blocks\n",
967                        o_blocks_count, n_blocks_count);
968
969         if (n_blocks_count == 0 || n_blocks_count == o_blocks_count)
970                 return 0;
971
972         if (n_blocks_count > (sector_t)(~0ULL) >> (sb->s_blocksize_bits - 9)) {
973                 printk(KERN_ERR "EXT4-fs: filesystem on %s:"
974                         " too large to resize to %llu blocks safely\n",
975                         sb->s_id, n_blocks_count);
976                 if (sizeof(sector_t) < 8)
977                         ext4_warning(sb, __func__,
978                         "CONFIG_LBD not enabled\n");
979                 return -EINVAL;
980         }
981
982         if (n_blocks_count < o_blocks_count) {
983                 ext4_warning(sb, __func__,
984                              "can't shrink FS - resize aborted");
985                 return -EBUSY;
986         }
987
988         /* Handle the remaining blocks in the last group only. */
989         ext4_get_group_no_and_offset(sb, o_blocks_count, NULL, &last);
990
991         if (last == 0) {
992                 ext4_warning(sb, __func__,
993                              "need to use ext2online to resize further");
994                 return -EPERM;
995         }
996
997         add = EXT4_BLOCKS_PER_GROUP(sb) - last;
998
999         if (o_blocks_count + add < o_blocks_count) {
1000                 ext4_warning(sb, __func__, "blocks_count overflow");
1001                 return -EINVAL;
1002         }
1003
1004         if (o_blocks_count + add > n_blocks_count)
1005                 add = n_blocks_count - o_blocks_count;
1006
1007         if (o_blocks_count + add < n_blocks_count)
1008                 ext4_warning(sb, __func__,
1009                              "will only finish group (%llu"
1010                              " blocks, %u new)",
1011                              o_blocks_count + add, add);
1012
1013         /* See if the device is actually as big as what was requested */
1014         bh = sb_bread(sb, o_blocks_count + add -1);
1015         if (!bh) {
1016                 ext4_warning(sb, __func__,
1017                              "can't read last block, resize aborted");
1018                 return -ENOSPC;
1019         }
1020         brelse(bh);
1021
1022         /* We will update the superblock, one block bitmap, and
1023          * one group descriptor via ext4_free_blocks().
1024          */
1025         handle = ext4_journal_start_sb(sb, 3);
1026         if (IS_ERR(handle)) {
1027                 err = PTR_ERR(handle);
1028                 ext4_warning(sb, __func__, "error %d on journal start", err);
1029                 goto exit_put;
1030         }
1031
1032         lock_super(sb);
1033         if (o_blocks_count != ext4_blocks_count(es)) {
1034                 ext4_warning(sb, __func__,
1035                              "multiple resizers run on filesystem!");
1036                 unlock_super(sb);
1037                 ext4_journal_stop(handle);
1038                 err = -EBUSY;
1039                 goto exit_put;
1040         }
1041
1042         if ((err = ext4_journal_get_write_access(handle,
1043                                                  EXT4_SB(sb)->s_sbh))) {
1044                 ext4_warning(sb, __func__,
1045                              "error %d on journal write access", err);
1046                 unlock_super(sb);
1047                 ext4_journal_stop(handle);
1048                 goto exit_put;
1049         }
1050         ext4_blocks_count_set(es, o_blocks_count + add);
1051         ext4_journal_dirty_metadata(handle, EXT4_SB(sb)->s_sbh);
1052         sb->s_dirt = 1;
1053         unlock_super(sb);
1054         ext4_debug("freeing blocks %llu through %llu\n", o_blocks_count,
1055                    o_blocks_count + add);
1056         ext4_free_blocks_sb(handle, sb, o_blocks_count, add, &freed_blocks);
1057         ext4_debug("freed blocks %llu through %llu\n", o_blocks_count,
1058                    o_blocks_count + add);
1059         if ((err = ext4_journal_stop(handle)))
1060                 goto exit_put;
1061         if (test_opt(sb, DEBUG))
1062                 printk(KERN_DEBUG "EXT4-fs: extended group to %llu blocks\n",
1063                        ext4_blocks_count(es));
1064         update_backups(sb, EXT4_SB(sb)->s_sbh->b_blocknr, (char *)es,
1065                        sizeof(struct ext4_super_block));
1066 exit_put:
1067         return err;
1068 } /* ext4_group_extend */