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Version: [ 2.6.11.8 ] [ 2.6.25 ] [ 2.6.25.8 ] [ 2.6.31.13 ] Architecture: [ i386 ]
  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 
 19 #define outside(b, first, last) ((b) < (first) || (b) >= (last))
 20 #define inside(b, first, last)  ((b) >= (first) && (b) < (last))
 21 
 22 static int verify_group_input(struct super_block *sb,
 23                               struct ext4_new_group_data *input)
 24 {
 25         struct ext4_sb_info *sbi = EXT4_SB(sb);
 26         struct ext4_super_block *es = sbi->s_es;
 27         ext4_fsblk_t start = ext4_blocks_count(es);
 28         ext4_fsblk_t end = start + input->blocks_count;
 29         ext4_group_t group = input->group;
 30         ext4_fsblk_t itend = input->inode_table + sbi->s_itb_per_group;
 31         unsigned overhead = ext4_bg_has_super(sb, group) ?
 32                 (1 + ext4_bg_num_gdb(sb, group) +
 33                  le16_to_cpu(es->s_reserved_gdt_blocks)) : 0;
 34         ext4_fsblk_t metaend = start + overhead;
 35         struct buffer_head *bh = NULL;
 36         ext4_grpblk_t free_blocks_count, offset;
 37         int err = -EINVAL;
 38 
 39         input->free_blocks_count = free_blocks_count =
 40                 input->blocks_count - 2 - overhead - sbi->s_itb_per_group;
 41 
 42         if (test_opt(sb, DEBUG))
 43                 printk(KERN_DEBUG "EXT4-fs: adding %s group %u: %u blocks "
 44                        "(%d free, %u reserved)\n",
 45                        ext4_bg_has_super(sb, input->group) ? "normal" :
 46                        "no-super", input->group, input->blocks_count,
 47                        free_blocks_count, input->reserved_blocks);
 48 
 49         ext4_get_group_no_and_offset(sb, start, NULL, &offset);
 50         if (group != sbi->s_groups_count)
 51                 ext4_warning(sb, __func__,
 52                              "Cannot add at group %u (only %u groups)",
 53                              input->group, sbi->s_groups_count);
 54         else if (offset != 0)
 55                         ext4_warning(sb, __func__, "Last group not full");
 56         else if (input->reserved_blocks > input->blocks_count / 5)
 57                 ext4_warning(sb, __func__, "Reserved blocks too high (%u)",
 58                              input->reserved_blocks);
 59         else if (free_blocks_count < 0)
 60                 ext4_warning(sb, __func__, "Bad blocks count %u",
 61                              input->blocks_count);
 62         else if (!(bh = sb_bread(sb, end - 1)))
 63                 ext4_warning(sb, __func__,
 64                              "Cannot read last block (%llu)",
 65                              end - 1);
 66         else if (outside(input->block_bitmap, start, end))
 67                 ext4_warning(sb, __func__,
 68                              "Block bitmap not in group (block %llu)",
 69                              (unsigned long long)input->block_bitmap);
 70         else if (outside(input->inode_bitmap, start, end))
 71                 ext4_warning(sb, __func__,
 72                              "Inode bitmap not in group (block %llu)",
 73                              (unsigned long long)input->inode_bitmap);
 74         else if (outside(input->inode_table, start, end) ||
 75                  outside(itend - 1, start, end))
 76                 ext4_warning(sb, __func__,
 77                              "Inode table not in group (blocks %llu-%llu)",
 78                              (unsigned long long)input->inode_table, itend - 1);
 79         else if (input->inode_bitmap == input->block_bitmap)
 80                 ext4_warning(sb, __func__,
 81                              "Block bitmap same as inode bitmap (%llu)",
 82                              (unsigned long long)input->block_bitmap);
 83         else if (inside(input->block_bitmap, input->inode_table, itend))
 84                 ext4_warning(sb, __func__,
 85                              "Block bitmap (%llu) in inode table (%llu-%llu)",
 86                              (unsigned long long)input->block_bitmap,
 87                              (unsigned long long)input->inode_table, itend - 1);
 88         else if (inside(input->inode_bitmap, input->inode_table, itend))
 89                 ext4_warning(sb, __func__,
 90                              "Inode bitmap (%llu) in inode table (%llu-%llu)",
 91                              (unsigned long long)input->inode_bitmap,
 92                              (unsigned long long)input->inode_table, itend - 1);
 93         else if (inside(input->block_bitmap, start, metaend))
 94                 ext4_warning(sb, __func__,
 95                              "Block bitmap (%llu) in GDT table"
 96                              " (%llu-%llu)",
 97                              (unsigned long long)input->block_bitmap,
 98                              start, metaend - 1);
 99         else if (inside(input->inode_bitmap, start, metaend))
100                 ext4_warning(sb, __func__,
101                              "Inode bitmap (%llu) in GDT table"
102                              " (%llu-%llu)",
103                              (unsigned long long)input->inode_bitmap,
104                              start, metaend - 1);
105         else if (inside(input->inode_table, start, metaend) ||
106                  inside(itend - 1, start, metaend))
107                 ext4_warning(sb, __func__,
108                              "Inode table (%llu-%llu) overlaps"
109                              "GDT table (%llu-%llu)",
110                              (unsigned long long)input->inode_table,
111                              itend - 1, start, metaend - 1);
112         else
113                 err = 0;
114         brelse(bh);
115 
116         return err;
117 }
118 
119 static struct buffer_head *bclean(handle_t *handle, struct super_block *sb,
120                                   ext4_fsblk_t blk)
121 {
122         struct buffer_head *bh;
123         int err;
124 
125         bh = sb_getblk(sb, blk);
126         if (!bh)
127                 return ERR_PTR(-EIO);
128         if ((err = ext4_journal_get_write_access(handle, bh))) {
129                 brelse(bh);
130                 bh = ERR_PTR(err);
131         } else {
132                 lock_buffer(bh);
133                 memset(bh->b_data, 0, sb->s_blocksize);
134                 set_buffer_uptodate(bh);
135                 unlock_buffer(bh);
136         }
137 
138         return bh;
139 }
140 
141 /*
142  * If we have fewer than thresh credits, extend by EXT4_MAX_TRANS_DATA.
143  * If that fails, restart the transaction & regain write access for the
144  * buffer head which is used for block_bitmap modifications.
145  */
146 static int extend_or_restart_transaction(handle_t *handle, int thresh,
147                                          struct buffer_head *bh)
148 {
149         int err;
150 
151         if (ext4_handle_has_enough_credits(handle, thresh))
152                 return 0;
153 
154         err = ext4_journal_extend(handle, EXT4_MAX_TRANS_DATA);
155         if (err < 0)
156                 return err;
157         if (err) {
158                 if ((err = ext4_journal_restart(handle, EXT4_MAX_TRANS_DATA)))
159                         return err;
160                 if ((err = ext4_journal_get_write_access(handle, bh)))
161                         return err;
162         }
163 
164         return 0;
165 }
166 
167 /*
168  * Set up the block and inode bitmaps, and the inode table for the new group.
169  * This doesn't need to be part of the main transaction, since we are only
170  * changing blocks outside the actual filesystem.  We still do journaling to
171  * ensure the recovery is correct in case of a failure just after resize.
172  * If any part of this fails, we simply abort the resize.
173  */
174 static int setup_new_group_blocks(struct super_block *sb,
175                                   struct ext4_new_group_data *input)
176 {
177         struct ext4_sb_info *sbi = EXT4_SB(sb);
178         ext4_fsblk_t start = ext4_group_first_block_no(sb, input->group);
179         int reserved_gdb = ext4_bg_has_super(sb, input->group) ?
180                 le16_to_cpu(sbi->s_es->s_reserved_gdt_blocks) : 0;
181         unsigned long gdblocks = ext4_bg_num_gdb(sb, input->group);
182         struct buffer_head *bh;
183         handle_t *handle;
184         ext4_fsblk_t block;
185         ext4_grpblk_t bit;
186         int i;
187         int err = 0, err2;
188 
189         /* This transaction may be extended/restarted along the way */
190         handle = ext4_journal_start_sb(sb, EXT4_MAX_TRANS_DATA);
191 
192         if (IS_ERR(handle))
193                 return PTR_ERR(handle);
194 
195         mutex_lock(&sbi->s_resize_lock);
196         if (input->group != sbi->s_groups_count) {
197                 err = -EBUSY;
198                 goto exit_journal;
199         }
200 
201         if (IS_ERR(bh = bclean(handle, sb, input->block_bitmap))) {
202                 err = PTR_ERR(bh);
203                 goto exit_journal;
204         }
205 
206         if (ext4_bg_has_super(sb, input->group)) {
207                 ext4_debug("mark backup superblock %#04llx (+0)\n", start);
208                 ext4_set_bit(0, bh->b_data);
209         }
210 
211         /* Copy all of the GDT blocks into the backup in this group */
212         for (i = 0, bit = 1, block = start + 1;
213              i < gdblocks; i++, block++, bit++) {
214                 struct buffer_head *gdb;
215 
216                 ext4_debug("update backup group %#04llx (+%d)\n", block, bit);
217 
218                 if ((err = extend_or_restart_transaction(handle, 1, bh)))
219                         goto exit_bh;
220 
221                 gdb = sb_getblk(sb, block);
222                 if (!gdb) {
223                         err = -EIO;
224                         goto exit_bh;
225                 }
226                 if ((err = ext4_journal_get_write_access(handle, gdb))) {
227                         brelse(gdb);
228                         goto exit_bh;
229                 }
230                 lock_buffer(gdb);
231                 memcpy(gdb->b_data, sbi->s_group_desc[i]->b_data, gdb->b_size);
232                 set_buffer_uptodate(gdb);
233                 unlock_buffer(gdb);
234                 ext4_handle_dirty_metadata(handle, NULL, gdb);
235                 ext4_set_bit(bit, bh->b_data);
236                 brelse(gdb);
237         }
238 
239         /* Zero out all of the reserved backup group descriptor table blocks */
240         for (i = 0, bit = gdblocks + 1, block = start + bit;
241              i < reserved_gdb; i++, block++, bit++) {
242                 struct buffer_head *gdb;
243 
244                 ext4_debug("clear reserved block %#04llx (+%d)\n", block, bit);
245 
246                 if ((err = extend_or_restart_transaction(handle, 1, bh)))
247                         goto exit_bh;
248 
249                 if (IS_ERR(gdb = bclean(handle, sb, block))) {
250                         err = PTR_ERR(gdb);
251                         goto exit_bh;
252                 }
253                 ext4_handle_dirty_metadata(handle, NULL, gdb);
254                 ext4_set_bit(bit, bh->b_data);
255                 brelse(gdb);
256         }
257         ext4_debug("mark block bitmap %#04llx (+%llu)\n", input->block_bitmap,
258                    input->block_bitmap - start);
259         ext4_set_bit(input->block_bitmap - start, bh->b_data);
260         ext4_debug("mark inode bitmap %#04llx (+%llu)\n", input->inode_bitmap,
261                    input->inode_bitmap - start);
262         ext4_set_bit(input->inode_bitmap - start, bh->b_data);
263 
264         /* Zero out all of the inode table blocks */
265         for (i = 0, block = input->inode_table, bit = block - start;
266              i < sbi->s_itb_per_group; i++, bit++, block++) {
267                 struct buffer_head *it;
268 
269                 ext4_debug("clear inode block %#04llx (+%d)\n", block, bit);
270 
271                 if ((err = extend_or_restart_transaction(handle, 1, bh)))
272                         goto exit_bh;
273 
274                 if (IS_ERR(it = bclean(handle, sb, block))) {
275                         err = PTR_ERR(it);
276                         goto exit_bh;
277                 }
278                 ext4_handle_dirty_metadata(handle, NULL, it);
279                 brelse(it);
280                 ext4_set_bit(bit, bh->b_data);
281         }
282 
283         if ((err = extend_or_restart_transaction(handle, 2, bh)))
284                 goto exit_bh;
285 
286         mark_bitmap_end(input->blocks_count, sb->s_blocksize * 8, bh->b_data);
287         ext4_handle_dirty_metadata(handle, NULL, bh);
288         brelse(bh);
289         /* Mark unused entries in inode bitmap used */
290         ext4_debug("clear inode bitmap %#04llx (+%llu)\n",
291                    input->inode_bitmap, input->inode_bitmap - start);
292         if (IS_ERR(bh = bclean(handle, sb, input->inode_bitmap))) {
293                 err = PTR_ERR(bh);
294                 goto exit_journal;
295         }
296 
297         mark_bitmap_end(EXT4_INODES_PER_GROUP(sb), sb->s_blocksize * 8,
298                         bh->b_data);
299         ext4_handle_dirty_metadata(handle, NULL, bh);
300 exit_bh:
301         brelse(bh);
302 
303 exit_journal:
304         mutex_unlock(&sbi->s_resize_lock);
305         if ((err2 = ext4_journal_stop(handle)) && !err)
306                 err = err2;
307 
308         return err;
309 }
310 
311 /*
312  * Iterate through the groups which hold BACKUP superblock/GDT copies in an
313  * ext4 filesystem.  The counters should be initialized to 1, 5, and 7 before
314  * calling this for the first time.  In a sparse filesystem it will be the
315  * sequence of powers of 3, 5, and 7: 1, 3, 5, 7, 9, 25, 27, 49, 81, ...
316  * For a non-sparse filesystem it will be every group: 1, 2, 3, 4, ...
317  */
318 static unsigned ext4_list_backups(struct super_block *sb, unsigned *three,
319                                   unsigned *five, unsigned *seven)
320 {
321         unsigned *min = three;
322         int mult = 3;
323         unsigned ret;
324 
325         if (!EXT4_HAS_RO_COMPAT_FEATURE(sb,
326                                         EXT4_FEATURE_RO_COMPAT_SPARSE_SUPER)) {
327                 ret = *min;
328                 *min += 1;
329                 return ret;
330         }
331 
332         if (*five < *min) {
333                 min = five;
334                 mult = 5;
335         }
336         if (*seven < *min) {
337                 min = seven;
338                 mult = 7;
339         }
340 
341         ret = *min;
342         *min *= mult;
343 
344         return ret;
345 }
346 
347 /*
348  * Check that all of the backup GDT blocks are held in the primary GDT block.
349  * It is assumed that they are stored in group order.  Returns the number of
350  * groups in current filesystem that have BACKUPS, or -ve error code.
351  */
352 static int verify_reserved_gdb(struct super_block *sb,
353                                struct buffer_head *primary)
354 {
355         const ext4_fsblk_t blk = primary->b_blocknr;
356         const ext4_group_t end = EXT4_SB(sb)->s_groups_count;
357         unsigned three = 1;
358         unsigned five = 5;
359         unsigned seven = 7;
360         unsigned grp;
361         __le32 *p = (__le32 *)primary->b_data;
362         int gdbackups = 0;
363 
364         while ((grp = ext4_list_backups(sb, &three, &five, &seven)) < end) {
365                 if (le32_to_cpu(*p++) !=
366                     grp * EXT4_BLOCKS_PER_GROUP(sb) + blk){
367                         ext4_warning(sb, __func__,
368                                      "reserved GDT %llu"
369                                      " missing grp %d (%llu)",
370                                      blk, grp,
371                                      grp *
372                                      (ext4_fsblk_t)EXT4_BLOCKS_PER_GROUP(sb) +
373                                      blk);
374                         return -EINVAL;
375                 }
376                 if (++gdbackups > EXT4_ADDR_PER_BLOCK(sb))
377                         return -EFBIG;
378         }
379 
380         return gdbackups;
381 }
382 
383 /*
384  * Called when we need to bring a reserved group descriptor table block into
385  * use from the resize inode.  The primary copy of the new GDT block currently
386  * is an indirect block (under the double indirect block in the resize inode).
387  * The new backup GDT blocks will be stored as leaf blocks in this indirect
388  * block, in group order.  Even though we know all the block numbers we need,
389  * we check to ensure that the resize inode has actually reserved these blocks.
390  *
391  * Don't need to update the block bitmaps because the blocks are still in use.
392  *
393  * We get all of the error cases out of the way, so that we are sure to not
394  * fail once we start modifying the data on disk, because JBD has no rollback.
395  */
396 static int add_new_gdb(handle_t *handle, struct inode *inode,
397                        struct ext4_new_group_data *input,
398                        struct buffer_head **primary)
399 {
400         struct super_block *sb = inode->i_sb;
401         struct ext4_super_block *es = EXT4_SB(sb)->s_es;
402         unsigned long gdb_num = input->group / EXT4_DESC_PER_BLOCK(sb);
403         ext4_fsblk_t gdblock = EXT4_SB(sb)->s_sbh->b_blocknr + 1 + gdb_num;
404         struct buffer_head **o_group_desc, **n_group_desc;
405         struct buffer_head *dind;
406         int gdbackups;
407         struct ext4_iloc iloc;
408         __le32 *data;
409         int err;
410 
411         if (test_opt(sb, DEBUG))
412                 printk(KERN_DEBUG
413                        "EXT4-fs: ext4_add_new_gdb: adding group block %lu\n",
414                        gdb_num);
415 
416         /*
417          * If we are not using the primary superblock/GDT copy don't resize,
418          * because the user tools have no way of handling this.  Probably a
419          * bad time to do it anyways.
420          */
421         if (EXT4_SB(sb)->s_sbh->b_blocknr !=
422             le32_to_cpu(EXT4_SB(sb)->s_es->s_first_data_block)) {
423                 ext4_warning(sb, __func__,
424                         "won't resize using backup superblock at %llu",
425                         (unsigned long long)EXT4_SB(sb)->s_sbh->b_blocknr);
426                 return -EPERM;
427         }
428 
429         *primary = sb_bread(sb, gdblock);
430         if (!*primary)
431                 return -EIO;
432 
433         if ((gdbackups = verify_reserved_gdb(sb, *primary)) < 0) {
434                 err = gdbackups;
435                 goto exit_bh;
436         }
437 
438         data = EXT4_I(inode)->i_data + EXT4_DIND_BLOCK;
439         dind = sb_bread(sb, le32_to_cpu(*data));
440         if (!dind) {
441                 err = -EIO;
442                 goto exit_bh;
443         }
444 
445         data = (__le32 *)dind->b_data;
446         if (le32_to_cpu(data[gdb_num % EXT4_ADDR_PER_BLOCK(sb)]) != gdblock) {
447                 ext4_warning(sb, __func__,
448                              "new group %u GDT block %llu not reserved",
449                              input->group, gdblock);
450                 err = -EINVAL;
451                 goto exit_dind;
452         }
453 
454         if ((err = ext4_journal_get_write_access(handle, EXT4_SB(sb)->s_sbh)))
455                 goto exit_dind;
456 
457         if ((err = ext4_journal_get_write_access(handle, *primary)))
458                 goto exit_sbh;
459 
460         if ((err = ext4_journal_get_write_access(handle, dind)))
461                 goto exit_primary;
462 
463         /* ext4_reserve_inode_write() gets a reference on the iloc */
464         if ((err = ext4_reserve_inode_write(handle, inode, &iloc)))
465                 goto exit_dindj;
466 
467         n_group_desc = kmalloc((gdb_num + 1) * sizeof(struct buffer_head *),
468                         GFP_NOFS);
469         if (!n_group_desc) {
470                 err = -ENOMEM;
471                 ext4_warning(sb, __func__,
472                               "not enough memory for %lu groups", gdb_num + 1);
473                 goto exit_inode;
474         }
475 
476         /*
477          * Finally, we have all of the possible failures behind us...
478          *
479          * Remove new GDT block from inode double-indirect block and clear out
480          * the new GDT block for use (which also "frees" the backup GDT blocks
481          * from the reserved inode).  We don't need to change the bitmaps for
482          * these blocks, because they are marked as in-use from being in the
483          * reserved inode, and will become GDT blocks (primary and backup).
484          */
485         data[gdb_num % EXT4_ADDR_PER_BLOCK(sb)] = 0;
486         ext4_handle_dirty_metadata(handle, NULL, dind);
487         brelse(dind);
488         inode->i_blocks -= (gdbackups + 1) * sb->s_blocksize >> 9;
489         ext4_mark_iloc_dirty(handle, inode, &iloc);
490         memset((*primary)->b_data, 0, sb->s_blocksize);
491         ext4_handle_dirty_metadata(handle, NULL, *primary);
492 
493         o_group_desc = EXT4_SB(sb)->s_group_desc;
494         memcpy(n_group_desc, o_group_desc,
495                EXT4_SB(sb)->s_gdb_count * sizeof(struct buffer_head *));
496         n_group_desc[gdb_num] = *primary;
497         EXT4_SB(sb)->s_group_desc = n_group_desc;
498         EXT4_SB(sb)->s_gdb_count++;
499         kfree(o_group_desc);
500 
501         le16_add_cpu(&es->s_reserved_gdt_blocks, -1);
502         ext4_handle_dirty_metadata(handle, NULL, EXT4_SB(sb)->s_sbh);
503 
504         return 0;
505 
506 exit_inode:
507         /* ext4_journal_release_buffer(handle, iloc.bh); */
508         brelse(iloc.bh);
509 exit_dindj:
510         /* ext4_journal_release_buffer(handle, dind); */
511 exit_primary:
512         /* ext4_journal_release_buffer(handle, *primary); */
513 exit_sbh:
514         /* ext4_journal_release_buffer(handle, *primary); */
515 exit_dind:
516         brelse(dind);
517 exit_bh:
518         brelse(*primary);
519 
520         ext4_debug("leaving with error %d\n", err);
521         return err;
522 }
523 
524 /*
525  * Called when we are adding a new group which has a backup copy of each of
526  * the GDT blocks (i.e. sparse group) and there are reserved GDT blocks.
527  * We need to add these reserved backup GDT blocks to the resize inode, so
528  * that they are kept for future resizing and not allocated to files.
529  *
530  * Each reserved backup GDT block will go into a different indirect block.
531  * The indirect blocks are actually the primary reserved GDT blocks,
532  * so we know in advance what their block numbers are.  We only get the
533  * double-indirect block to verify it is pointing to the primary reserved
534  * GDT blocks so we don't overwrite a data block by accident.  The reserved
535  * backup GDT blocks are stored in their reserved primary GDT block.
536  */
537 static int reserve_backup_gdb(handle_t *handle, struct inode *inode,
538                               struct ext4_new_group_data *input)
539 {
540         struct super_block *sb = inode->i_sb;
541         int reserved_gdb =le16_to_cpu(EXT4_SB(sb)->s_es->s_reserved_gdt_blocks);
542         struct buffer_head **primary;
543         struct buffer_head *dind;
544         struct ext4_iloc iloc;
545         ext4_fsblk_t blk;
546         __le32 *data, *end;
547         int gdbackups = 0;
548         int res, i;
549         int err;
550 
551         primary = kmalloc(reserved_gdb * sizeof(*primary), GFP_NOFS);
552         if (!primary)
553                 return -ENOMEM;
554 
555         data = EXT4_I(inode)->i_data + EXT4_DIND_BLOCK;
556         dind = sb_bread(sb, le32_to_cpu(*data));
557         if (!dind) {
558                 err = -EIO;
559                 goto exit_free;
560         }
561 
562         blk = EXT4_SB(sb)->s_sbh->b_blocknr + 1 + EXT4_SB(sb)->s_gdb_count;
563         data = (__le32 *)dind->b_data + (EXT4_SB(sb)->s_gdb_count %
564                                          EXT4_ADDR_PER_BLOCK(sb));
565         end = (__le32 *)dind->b_data + EXT4_ADDR_PER_BLOCK(sb);
566 
567         /* Get each reserved primary GDT block and verify it holds backups */
568         for (res = 0; res < reserved_gdb; res++, blk++) {
569                 if (le32_to_cpu(*data) != blk) {
570                         ext4_warning(sb, __func__,
571                                      "reserved block %llu"
572                                      " not at offset %ld",
573                                      blk,
574                                      (long)(data - (__le32 *)dind->b_data));
575                         err = -EINVAL;
576                         goto exit_bh;
577                 }
578                 primary[res] = sb_bread(sb, blk);
579                 if (!primary[res]) {
580                         err = -EIO;
581                         goto exit_bh;
582                 }
583                 if ((gdbackups = verify_reserved_gdb(sb, primary[res])) < 0) {
584                         brelse(primary[res]);
585                         err = gdbackups;
586                         goto exit_bh;
587                 }
588                 if (++data >= end)
589                         data = (__le32 *)dind->b_data;
590         }
591 
592         for (i = 0; i < reserved_gdb; i++) {
593                 if ((err = ext4_journal_get_write_access(handle, primary[i]))) {
594                         /*
595                         int j;
596                         for (j = 0; j < i; j++)
597                                 ext4_journal_release_buffer(handle, primary[j]);
598                          */
599                         goto exit_bh;
600                 }
601         }
602 
603         if ((err = ext4_reserve_inode_write(handle, inode, &iloc)))
604                 goto exit_bh;
605 
606         /*
607          * Finally we can add each of the reserved backup GDT blocks from
608          * the new group to its reserved primary GDT block.
609          */
610         blk = input->group * EXT4_BLOCKS_PER_GROUP(sb);
611         for (i = 0; i < reserved_gdb; i++) {
612                 int err2;
613                 data = (__le32 *)primary[i]->b_data;
614                 /* printk("reserving backup %lu[%u] = %lu\n",
615                        primary[i]->b_blocknr, gdbackups,
616                        blk + primary[i]->b_blocknr); */
617                 data[gdbackups] = cpu_to_le32(blk + primary[i]->b_blocknr);
618                 err2 = ext4_handle_dirty_metadata(handle, NULL, primary[i]);
619                 if (!err)
620                         err = err2;
621         }
622         inode->i_blocks += reserved_gdb * sb->s_blocksize >> 9;
623         ext4_mark_iloc_dirty(handle, inode, &iloc);
624 
625 exit_bh:
626         while (--res >= 0)
627                 brelse(primary[res]);
628         brelse(dind);
629 
630 exit_free:
631         kfree(primary);
632 
633         return err;
634 }
635 
636 /*
637  * Update the backup copies of the ext4 metadata.  These don't need to be part
638  * of the main resize transaction, because e2fsck will re-write them if there
639  * is a problem (basically only OOM will cause a problem).  However, we
640  * _should_ update the backups if possible, in case the primary gets trashed
641  * for some reason and we need to run e2fsck from a backup superblock.  The
642  * important part is that the new block and inode counts are in the backup
643  * superblocks, and the location of the new group metadata in the GDT backups.
644  *
645  * We do not need take the s_resize_lock for this, because these
646  * blocks are not otherwise touched by the filesystem code when it is
647  * mounted.  We don't need to worry about last changing from
648  * sbi->s_groups_count, because the worst that can happen is that we
649  * do not copy the full number of backups at this time.  The resize
650  * which changed s_groups_count will backup again.
651  */
652 static void update_backups(struct super_block *sb,
653                            int blk_off, char *data, int size)
654 {
655         struct ext4_sb_info *sbi = EXT4_SB(sb);
656         const ext4_group_t last = sbi->s_groups_count;
657         const int bpg = EXT4_BLOCKS_PER_GROUP(sb);
658         unsigned three = 1;
659         unsigned five = 5;
660         unsigned seven = 7;
661         ext4_group_t group;
662         int rest = sb->s_blocksize - size;
663         handle_t *handle;
664         int err = 0, err2;
665 
666         handle = ext4_journal_start_sb(sb, EXT4_MAX_TRANS_DATA);
667         if (IS_ERR(handle)) {
668                 group = 1;
669                 err = PTR_ERR(handle);
670                 goto exit_err;
671         }
672 
673         while ((group = ext4_list_backups(sb, &three, &five, &seven)) < last) {
674                 struct buffer_head *bh;
675 
676                 /* Out of journal space, and can't get more - abort - so sad */
677                 if (ext4_handle_valid(handle) &&
678                     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_handle_dirty_metadata(handle, NULL, 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 %u (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 num_grp_locked = 0;
750         int err, err2;
751 
752         gdb_num = input->group / EXT4_DESC_PER_BLOCK(sb);
753         gdb_off = input->group % EXT4_DESC_PER_BLOCK(sb);
754 
755         if (gdb_off == 0 && !EXT4_HAS_RO_COMPAT_FEATURE(sb,
756                                         EXT4_FEATURE_RO_COMPAT_SPARSE_SUPER)) {
757                 ext4_warning(sb, __func__,
758                              "Can't resize non-sparse filesystem further");
759                 return -EPERM;
760         }
761 
762         if (ext4_blocks_count(es) + input->blocks_count <
763             ext4_blocks_count(es)) {
764                 ext4_warning(sb, __func__, "blocks_count overflow");
765                 return -EINVAL;
766         }
767 
768         if (le32_to_cpu(es->s_inodes_count) + EXT4_INODES_PER_GROUP(sb) <
769             le32_to_cpu(es->s_inodes_count)) {
770                 ext4_warning(sb, __func__, "inodes_count overflow");
771                 return -EINVAL;
772         }
773 
774         if (reserved_gdb || gdb_off == 0) {
775                 if (!EXT4_HAS_COMPAT_FEATURE(sb,
776                                              EXT4_FEATURE_COMPAT_RESIZE_INODE)
777                     || !le16_to_cpu(es->s_reserved_gdt_blocks)) {
778                         ext4_warning(sb, __func__,
779                                      "No reserved GDT blocks, can't resize");
780                         return -EPERM;
781                 }
782                 inode = ext4_iget(sb, EXT4_RESIZE_INO);
783                 if (IS_ERR(inode)) {
784                         ext4_warning(sb, __func__,
785                                      "Error opening resize inode");
786                         return PTR_ERR(inode);
787                 }
788         }
789 
790 
791         if ((err = verify_group_input(sb, input)))
792                 goto exit_put;
793 
794         if ((err = setup_new_group_blocks(sb, input)))
795                 goto exit_put;
796 
797         /*
798          * We will always be modifying at least the superblock and a GDT
799          * block.  If we are adding a group past the last current GDT block,
800          * we will also modify the inode and the dindirect block.  If we
801          * are adding a group with superblock/GDT backups  we will also
802          * modify each of the reserved GDT dindirect blocks.
803          */
804         handle = ext4_journal_start_sb(sb,
805                                        ext4_bg_has_super(sb, input->group) ?
806                                        3 + reserved_gdb : 4);
807         if (IS_ERR(handle)) {
808                 err = PTR_ERR(handle);
809                 goto exit_put;
810         }
811 
812         mutex_lock(&sbi->s_resize_lock);
813         if (input->group != sbi->s_groups_count) {
814                 ext4_warning(sb, __func__,
815                              "multiple resizers run on filesystem!");
816                 err = -EBUSY;
817                 goto exit_journal;
818         }
819 
820         if ((err = ext4_journal_get_write_access(handle, sbi->s_sbh)))
821                 goto exit_journal;
822 
823         /*
824          * We will only either add reserved group blocks to a backup group
825          * or remove reserved blocks for the first group in a new group block.
826          * Doing both would be mean more complex code, and sane people don't
827          * use non-sparse filesystems anymore.  This is already checked above.
828          */
829         if (gdb_off) {
830                 primary = sbi->s_group_desc[gdb_num];
831                 if ((err = ext4_journal_get_write_access(handle, primary)))
832                         goto exit_journal;
833 
834                 if (reserved_gdb && ext4_bg_num_gdb(sb, input->group) &&
835                     (err = reserve_backup_gdb(handle, inode, input)))
836                         goto exit_journal;
837         } else if ((err = add_new_gdb(handle, inode, input, &primary)))
838                 goto exit_journal;
839 
840         /*
841          * OK, now we've set up the new group.  Time to make it active.
842          *
843          * We do not lock all allocations via s_resize_lock
844          * so we have to be safe wrt. concurrent accesses the group
845          * data.  So we need to be careful to set all of the relevant
846          * group descriptor data etc. *before* we enable the group.
847          *
848          * The key field here is sbi->s_groups_count: as long as
849          * that retains its old value, nobody is going to access the new
850          * group.
851          *
852          * So first we update all the descriptor metadata for the new
853          * group; then we update the total disk blocks count; then we
854          * update the groups count to enable the group; then finally we
855          * update the free space counts so that the system can start
856          * using the new disk blocks.
857          */
858 
859         num_grp_locked = ext4_mb_get_buddy_cache_lock(sb, input->group);
860         /* Update group descriptor block for new group */
861         gdp = (struct ext4_group_desc *)((char *)primary->b_data +
862                                          gdb_off * EXT4_DESC_SIZE(sb));
863 
864         memset(gdp, 0, EXT4_DESC_SIZE(sb));
865         ext4_block_bitmap_set(sb, gdp, input->block_bitmap); /* LV FIXME */
866         ext4_inode_bitmap_set(sb, gdp, input->inode_bitmap); /* LV FIXME */
867         ext4_inode_table_set(sb, gdp, input->inode_table); /* LV FIXME */
868         ext4_free_blks_set(sb, gdp, input->free_blocks_count);
869         ext4_free_inodes_set(sb, gdp, EXT4_INODES_PER_GROUP(sb));
870         gdp->bg_flags = cpu_to_le16(EXT4_BG_INODE_ZEROED);
871         gdp->bg_checksum = ext4_group_desc_csum(sbi, input->group, gdp);
872 
873         /*
874          * We can allocate memory for mb_alloc based on the new group
875          * descriptor
876          */
877         err = ext4_mb_add_groupinfo(sb, input->group, gdp);
878         if (err) {
879                 ext4_mb_put_buddy_cache_lock(sb, input->group, num_grp_locked);
880                 goto exit_journal;
881         }
882 
883         /*
884          * Make the new blocks and inodes valid next.  We do this before
885          * increasing the group count so that once the group is enabled,
886          * all of its blocks and inodes are already valid.
887          *
888          * We always allocate group-by-group, then block-by-block or
889          * inode-by-inode within a group, so enabling these
890          * blocks/inodes before the group is live won't actually let us
891          * allocate the new space yet.
892          */
893         ext4_blocks_count_set(es, ext4_blocks_count(es) +
894                 input->blocks_count);
895         le32_add_cpu(&es->s_inodes_count, EXT4_INODES_PER_GROUP(sb));
896 
897         /*
898          * We need to protect s_groups_count against other CPUs seeing
899          * inconsistent state in the superblock.
900          *
901          * The precise rules we use are:
902          *
903          * * Writers of s_groups_count *must* hold s_resize_lock
904          * AND
905          * * Writers must perform a smp_wmb() after updating all dependent
906          *   data and before modifying the groups count
907          *
908          * * Readers must hold s_resize_lock over the access
909          * OR
910          * * Readers must perform an smp_rmb() after reading the groups count
911          *   and before reading any dependent data.
912          *
913          * NB. These rules can be relaxed when checking the group count
914          * while freeing data, as we can only allocate from a block
915          * group after serialising against the group count, and we can
916          * only then free after serialising in turn against that
917          * allocation.
918          */
919         smp_wmb();
920 
921         /* Update the global fs size fields */
922         sbi->s_groups_count++;
923         ext4_mb_put_buddy_cache_lock(sb, input->group, num_grp_locked);
924 
925         ext4_handle_dirty_metadata(handle, NULL, primary);
926 
927         /* Update the reserved block counts only once the new group is
928          * active. */
929         ext4_r_blocks_count_set(es, ext4_r_blocks_count(es) +
930                 input->reserved_blocks);
931 
932         /* Update the free space counts */
933         percpu_counter_add(&sbi->s_freeblocks_counter,
934                            input->free_blocks_count);
935         percpu_counter_add(&sbi->s_freeinodes_counter,
936                            EXT4_INODES_PER_GROUP(sb));
937 
938         if (EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_FLEX_BG)) {
939                 ext4_group_t flex_group;
940                 flex_group = ext4_flex_group(sbi, input->group);
941                 atomic_add(input->free_blocks_count,
942                            &sbi->s_flex_groups[flex_group].free_blocks);
943                 atomic_add(EXT4_INODES_PER_GROUP(sb),
944                            &sbi->s_flex_groups[flex_group].free_inodes);
945         }
946 
947         ext4_handle_dirty_metadata(handle, NULL, sbi->s_sbh);
948         sb->s_dirt = 1;
949 
950 exit_journal:
951         mutex_unlock(&sbi->s_resize_lock);
952         if ((err2 = ext4_journal_stop(handle)) && !err)
953                 err = err2;
954         if (!err) {
955                 update_backups(sb, sbi->s_sbh->b_blocknr, (char *)es,
956                                sizeof(struct ext4_super_block));
957                 update_backups(sb, primary->b_blocknr, primary->b_data,
958                                primary->b_size);
959         }
960 exit_put:
961         iput(inode);
962         return err;
963 } /* ext4_group_add */
964 
965 /*
966  * Extend the filesystem to the new number of blocks specified.  This entry
967  * point is only used to extend the current filesystem to the end of the last
968  * existing group.  It can be accessed via ioctl, or by "remount,resize=<size>"
969  * for emergencies (because it has no dependencies on reserved blocks).
970  *
971  * If we _really_ wanted, we could use default values to call ext4_group_add()
972  * allow the "remount" trick to work for arbitrary resizing, assuming enough
973  * GDT blocks are reserved to grow to the desired size.
974  */
975 int ext4_group_extend(struct super_block *sb, struct ext4_super_block *es,
976                       ext4_fsblk_t n_blocks_count)
977 {
978         ext4_fsblk_t o_blocks_count;
979         ext4_group_t o_groups_count;
980         ext4_grpblk_t last;
981         ext4_grpblk_t add;
982         struct buffer_head *bh;
983         handle_t *handle;
984         int err;
985         ext4_group_t group;
986 
987         /* We don't need to worry about locking wrt other resizers just
988          * yet: we're going to revalidate es->s_blocks_count after
989          * taking the s_resize_lock below. */
990         o_blocks_count = ext4_blocks_count(es);
991         o_groups_count = EXT4_SB(sb)->s_groups_count;
992 
993         if (test_opt(sb, DEBUG))
994                 printk(KERN_DEBUG "EXT4-fs: extending last group from %llu uto %llu blocks\n",
995                        o_blocks_count, n_blocks_count);
996 
997         if (n_blocks_count == 0 || n_blocks_count == o_blocks_count)
998                 return 0;
999 
1000         if (n_blocks_count > (sector_t)(~0ULL) >> (sb->s_blocksize_bits - 9)) {
1001                 printk(KERN_ERR "EXT4-fs: filesystem on %s:"
1002                         " too large to resize to %llu blocks safely\n",
1003                         sb->s_id, n_blocks_count);
1004                 if (sizeof(sector_t) < 8)
1005                         ext4_warning(sb, __func__, "CONFIG_LBDAF not enabled");
1006                 return -EINVAL;
1007         }
1008 
1009         if (n_blocks_count < o_blocks_count) {
1010                 ext4_warning(sb, __func__,
1011                              "can't shrink FS - resize aborted");
1012                 return -EBUSY;
1013         }
1014 
1015         /* Handle the remaining blocks in the last group only. */
1016         ext4_get_group_no_and_offset(sb, o_blocks_count, &group, &last);
1017 
1018         if (last == 0) {
1019                 ext4_warning(sb, __func__,
1020                              "need to use ext2online to resize further");
1021                 return -EPERM;
1022         }
1023 
1024         add = EXT4_BLOCKS_PER_GROUP(sb) - last;
1025 
1026         if (o_blocks_count + add < o_blocks_count) {
1027                 ext4_warning(sb, __func__, "blocks_count overflow");
1028                 return -EINVAL;
1029         }
1030 
1031         if (o_blocks_count + add > n_blocks_count)
1032                 add = n_blocks_count - o_blocks_count;
1033 
1034         if (o_blocks_count + add < n_blocks_count)
1035                 ext4_warning(sb, __func__,
1036                              "will only finish group (%llu"
1037                              " blocks, %u new)",
1038                              o_blocks_count + add, add);
1039 
1040         /* See if the device is actually as big as what was requested */
1041         bh = sb_bread(sb, o_blocks_count + add - 1);
1042         if (!bh) {
1043                 ext4_warning(sb, __func__,
1044                              "can't read last block, resize aborted");
1045                 return -ENOSPC;
1046         }
1047         brelse(bh);
1048 
1049         /* We will update the superblock, one block bitmap, and
1050          * one group descriptor via ext4_free_blocks().
1051          */
1052         handle = ext4_journal_start_sb(sb, 3);
1053         if (IS_ERR(handle)) {
1054                 err = PTR_ERR(handle);
1055                 ext4_warning(sb, __func__, "error %d on journal start", err);
1056                 goto exit_put;
1057         }
1058 
1059         mutex_lock(&EXT4_SB(sb)->s_resize_lock);
1060         if (o_blocks_count != ext4_blocks_count(es)) {
1061                 ext4_warning(sb, __func__,
1062                              "multiple resizers run on filesystem!");
1063                 mutex_unlock(&EXT4_SB(sb)->s_resize_lock);
1064                 ext4_journal_stop(handle);
1065                 err = -EBUSY;
1066                 goto exit_put;
1067         }
1068 
1069         if ((err = ext4_journal_get_write_access(handle,
1070                                                  EXT4_SB(sb)->s_sbh))) {
1071                 ext4_warning(sb, __func__,
1072                              "error %d on journal write access", err);
1073                 mutex_unlock(&EXT4_SB(sb)->s_resize_lock);
1074                 ext4_journal_stop(handle);
1075                 goto exit_put;
1076         }
1077         ext4_blocks_count_set(es, o_blocks_count + add);
1078         ext4_handle_dirty_metadata(handle, NULL, EXT4_SB(sb)->s_sbh);
1079         sb->s_dirt = 1;
1080         mutex_unlock(&EXT4_SB(sb)->s_resize_lock);
1081         ext4_debug("freeing blocks %llu through %llu\n", o_blocks_count,
1082                    o_blocks_count + add);
1083         /* We add the blocks to the bitmap and set the group need init bit */
1084         ext4_add_groupblocks(handle, sb, o_blocks_count, add);
1085         ext4_debug("freed blocks %llu through %llu\n", o_blocks_count,
1086                    o_blocks_count + add);
1087         if ((err = ext4_journal_stop(handle)))
1088                 goto exit_put;
1089 
1090         if (test_opt(sb, DEBUG))
1091                 printk(KERN_DEBUG "EXT4-fs: extended group to %llu blocks\n",
1092                        ext4_blocks_count(es));
1093         update_backups(sb, EXT4_SB(sb)->s_sbh->b_blocknr, (char *)es,
1094                        sizeof(struct ext4_super_block));
1095 exit_put:
1096         return err;
1097 } /* ext4_group_extend */
1098 
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