Merge branch 'for-linus' of git://git.infradead.org/users/eparis/selinux into for...
[pandora-kernel.git] / fs / ext4 / balloc.c
1 /*
2  *  linux/fs/ext4/balloc.c
3  *
4  * Copyright (C) 1992, 1993, 1994, 1995
5  * Remy Card (card@masi.ibp.fr)
6  * Laboratoire MASI - Institut Blaise Pascal
7  * Universite Pierre et Marie Curie (Paris VI)
8  *
9  *  Enhanced block allocation by Stephen Tweedie (sct@redhat.com), 1993
10  *  Big-endian to little-endian byte-swapping/bitmaps by
11  *        David S. Miller (davem@caip.rutgers.edu), 1995
12  */
13
14 #include <linux/time.h>
15 #include <linux/capability.h>
16 #include <linux/fs.h>
17 #include <linux/jbd2.h>
18 #include <linux/quotaops.h>
19 #include <linux/buffer_head.h>
20 #include "ext4.h"
21 #include "ext4_jbd2.h"
22 #include "mballoc.h"
23
24 #include <trace/events/ext4.h>
25
26 /*
27  * balloc.c contains the blocks allocation and deallocation routines
28  */
29
30 /*
31  * Calculate the block group number and offset, given a block number
32  */
33 void ext4_get_group_no_and_offset(struct super_block *sb, ext4_fsblk_t blocknr,
34                 ext4_group_t *blockgrpp, ext4_grpblk_t *offsetp)
35 {
36         struct ext4_super_block *es = EXT4_SB(sb)->s_es;
37         ext4_grpblk_t offset;
38
39         blocknr = blocknr - le32_to_cpu(es->s_first_data_block);
40         offset = do_div(blocknr, EXT4_BLOCKS_PER_GROUP(sb));
41         if (offsetp)
42                 *offsetp = offset;
43         if (blockgrpp)
44                 *blockgrpp = blocknr;
45
46 }
47
48 static int ext4_block_in_group(struct super_block *sb, ext4_fsblk_t block,
49                         ext4_group_t block_group)
50 {
51         ext4_group_t actual_group;
52         ext4_get_group_no_and_offset(sb, block, &actual_group, NULL);
53         if (actual_group == block_group)
54                 return 1;
55         return 0;
56 }
57
58 static int ext4_group_used_meta_blocks(struct super_block *sb,
59                                        ext4_group_t block_group,
60                                        struct ext4_group_desc *gdp)
61 {
62         ext4_fsblk_t tmp;
63         struct ext4_sb_info *sbi = EXT4_SB(sb);
64         /* block bitmap, inode bitmap, and inode table blocks */
65         int used_blocks = sbi->s_itb_per_group + 2;
66
67         if (EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_FLEX_BG)) {
68                 if (!ext4_block_in_group(sb, ext4_block_bitmap(sb, gdp),
69                                         block_group))
70                         used_blocks--;
71
72                 if (!ext4_block_in_group(sb, ext4_inode_bitmap(sb, gdp),
73                                         block_group))
74                         used_blocks--;
75
76                 tmp = ext4_inode_table(sb, gdp);
77                 for (; tmp < ext4_inode_table(sb, gdp) +
78                                 sbi->s_itb_per_group; tmp++) {
79                         if (!ext4_block_in_group(sb, tmp, block_group))
80                                 used_blocks -= 1;
81                 }
82         }
83         return used_blocks;
84 }
85
86 /* Initializes an uninitialized block bitmap if given, and returns the
87  * number of blocks free in the group. */
88 unsigned ext4_init_block_bitmap(struct super_block *sb, struct buffer_head *bh,
89                  ext4_group_t block_group, struct ext4_group_desc *gdp)
90 {
91         int bit, bit_max;
92         ext4_group_t ngroups = ext4_get_groups_count(sb);
93         unsigned free_blocks, group_blocks;
94         struct ext4_sb_info *sbi = EXT4_SB(sb);
95
96         if (bh) {
97                 J_ASSERT_BH(bh, buffer_locked(bh));
98
99                 /* If checksum is bad mark all blocks used to prevent allocation
100                  * essentially implementing a per-group read-only flag. */
101                 if (!ext4_group_desc_csum_verify(sbi, block_group, gdp)) {
102                         ext4_error(sb, "Checksum bad for group %u",
103                                         block_group);
104                         ext4_free_blks_set(sb, gdp, 0);
105                         ext4_free_inodes_set(sb, gdp, 0);
106                         ext4_itable_unused_set(sb, gdp, 0);
107                         memset(bh->b_data, 0xff, sb->s_blocksize);
108                         return 0;
109                 }
110                 memset(bh->b_data, 0, sb->s_blocksize);
111         }
112
113         /* Check for superblock and gdt backups in this group */
114         bit_max = ext4_bg_has_super(sb, block_group);
115
116         if (!EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_META_BG) ||
117             block_group < le32_to_cpu(sbi->s_es->s_first_meta_bg) *
118                           sbi->s_desc_per_block) {
119                 if (bit_max) {
120                         bit_max += ext4_bg_num_gdb(sb, block_group);
121                         bit_max +=
122                                 le16_to_cpu(sbi->s_es->s_reserved_gdt_blocks);
123                 }
124         } else { /* For META_BG_BLOCK_GROUPS */
125                 bit_max += ext4_bg_num_gdb(sb, block_group);
126         }
127
128         if (block_group == ngroups - 1) {
129                 /*
130                  * Even though mke2fs always initialize first and last group
131                  * if some other tool enabled the EXT4_BG_BLOCK_UNINIT we need
132                  * to make sure we calculate the right free blocks
133                  */
134                 group_blocks = ext4_blocks_count(sbi->s_es) -
135                         ext4_group_first_block_no(sb, ngroups - 1);
136         } else {
137                 group_blocks = EXT4_BLOCKS_PER_GROUP(sb);
138         }
139
140         free_blocks = group_blocks - bit_max;
141
142         if (bh) {
143                 ext4_fsblk_t start, tmp;
144                 int flex_bg = 0;
145
146                 for (bit = 0; bit < bit_max; bit++)
147                         ext4_set_bit(bit, bh->b_data);
148
149                 start = ext4_group_first_block_no(sb, block_group);
150
151                 if (EXT4_HAS_INCOMPAT_FEATURE(sb,
152                                               EXT4_FEATURE_INCOMPAT_FLEX_BG))
153                         flex_bg = 1;
154
155                 /* Set bits for block and inode bitmaps, and inode table */
156                 tmp = ext4_block_bitmap(sb, gdp);
157                 if (!flex_bg || ext4_block_in_group(sb, tmp, block_group))
158                         ext4_set_bit(tmp - start, bh->b_data);
159
160                 tmp = ext4_inode_bitmap(sb, gdp);
161                 if (!flex_bg || ext4_block_in_group(sb, tmp, block_group))
162                         ext4_set_bit(tmp - start, bh->b_data);
163
164                 tmp = ext4_inode_table(sb, gdp);
165                 for (; tmp < ext4_inode_table(sb, gdp) +
166                                 sbi->s_itb_per_group; tmp++) {
167                         if (!flex_bg ||
168                                 ext4_block_in_group(sb, tmp, block_group))
169                                 ext4_set_bit(tmp - start, bh->b_data);
170                 }
171                 /*
172                  * Also if the number of blocks within the group is
173                  * less than the blocksize * 8 ( which is the size
174                  * of bitmap ), set rest of the block bitmap to 1
175                  */
176                 ext4_mark_bitmap_end(group_blocks, sb->s_blocksize * 8,
177                                      bh->b_data);
178         }
179         return free_blocks - ext4_group_used_meta_blocks(sb, block_group, gdp);
180 }
181
182
183 /*
184  * The free blocks are managed by bitmaps.  A file system contains several
185  * blocks groups.  Each group contains 1 bitmap block for blocks, 1 bitmap
186  * block for inodes, N blocks for the inode table and data blocks.
187  *
188  * The file system contains group descriptors which are located after the
189  * super block.  Each descriptor contains the number of the bitmap block and
190  * the free blocks count in the block.  The descriptors are loaded in memory
191  * when a file system is mounted (see ext4_fill_super).
192  */
193
194 /**
195  * ext4_get_group_desc() -- load group descriptor from disk
196  * @sb:                 super block
197  * @block_group:        given block group
198  * @bh:                 pointer to the buffer head to store the block
199  *                      group descriptor
200  */
201 struct ext4_group_desc * ext4_get_group_desc(struct super_block *sb,
202                                              ext4_group_t block_group,
203                                              struct buffer_head **bh)
204 {
205         unsigned int group_desc;
206         unsigned int offset;
207         ext4_group_t ngroups = ext4_get_groups_count(sb);
208         struct ext4_group_desc *desc;
209         struct ext4_sb_info *sbi = EXT4_SB(sb);
210
211         if (block_group >= ngroups) {
212                 ext4_error(sb, "block_group >= groups_count - block_group = %u,"
213                            " groups_count = %u", block_group, ngroups);
214
215                 return NULL;
216         }
217
218         group_desc = block_group >> EXT4_DESC_PER_BLOCK_BITS(sb);
219         offset = block_group & (EXT4_DESC_PER_BLOCK(sb) - 1);
220         if (!sbi->s_group_desc[group_desc]) {
221                 ext4_error(sb, "Group descriptor not loaded - "
222                            "block_group = %u, group_desc = %u, desc = %u",
223                            block_group, group_desc, offset);
224                 return NULL;
225         }
226
227         desc = (struct ext4_group_desc *)(
228                 (__u8 *)sbi->s_group_desc[group_desc]->b_data +
229                 offset * EXT4_DESC_SIZE(sb));
230         if (bh)
231                 *bh = sbi->s_group_desc[group_desc];
232         return desc;
233 }
234
235 static int ext4_valid_block_bitmap(struct super_block *sb,
236                                         struct ext4_group_desc *desc,
237                                         unsigned int block_group,
238                                         struct buffer_head *bh)
239 {
240         ext4_grpblk_t offset;
241         ext4_grpblk_t next_zero_bit;
242         ext4_fsblk_t bitmap_blk;
243         ext4_fsblk_t group_first_block;
244
245         if (EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_FLEX_BG)) {
246                 /* with FLEX_BG, the inode/block bitmaps and itable
247                  * blocks may not be in the group at all
248                  * so the bitmap validation will be skipped for those groups
249                  * or it has to also read the block group where the bitmaps
250                  * are located to verify they are set.
251                  */
252                 return 1;
253         }
254         group_first_block = ext4_group_first_block_no(sb, block_group);
255
256         /* check whether block bitmap block number is set */
257         bitmap_blk = ext4_block_bitmap(sb, desc);
258         offset = bitmap_blk - group_first_block;
259         if (!ext4_test_bit(offset, bh->b_data))
260                 /* bad block bitmap */
261                 goto err_out;
262
263         /* check whether the inode bitmap block number is set */
264         bitmap_blk = ext4_inode_bitmap(sb, desc);
265         offset = bitmap_blk - group_first_block;
266         if (!ext4_test_bit(offset, bh->b_data))
267                 /* bad block bitmap */
268                 goto err_out;
269
270         /* check whether the inode table block number is set */
271         bitmap_blk = ext4_inode_table(sb, desc);
272         offset = bitmap_blk - group_first_block;
273         next_zero_bit = ext4_find_next_zero_bit(bh->b_data,
274                                 offset + EXT4_SB(sb)->s_itb_per_group,
275                                 offset);
276         if (next_zero_bit >= offset + EXT4_SB(sb)->s_itb_per_group)
277                 /* good bitmap for inode tables */
278                 return 1;
279
280 err_out:
281         ext4_error(sb, "Invalid block bitmap - block_group = %d, block = %llu",
282                         block_group, bitmap_blk);
283         return 0;
284 }
285 /**
286  * ext4_read_block_bitmap()
287  * @sb:                 super block
288  * @block_group:        given block group
289  *
290  * Read the bitmap for a given block_group,and validate the
291  * bits for block/inode/inode tables are set in the bitmaps
292  *
293  * Return buffer_head on success or NULL in case of failure.
294  */
295 struct buffer_head *
296 ext4_read_block_bitmap(struct super_block *sb, ext4_group_t block_group)
297 {
298         struct ext4_group_desc *desc;
299         struct buffer_head *bh = NULL;
300         ext4_fsblk_t bitmap_blk;
301
302         desc = ext4_get_group_desc(sb, block_group, NULL);
303         if (!desc)
304                 return NULL;
305         bitmap_blk = ext4_block_bitmap(sb, desc);
306         bh = sb_getblk(sb, bitmap_blk);
307         if (unlikely(!bh)) {
308                 ext4_error(sb, "Cannot read block bitmap - "
309                             "block_group = %u, block_bitmap = %llu",
310                             block_group, bitmap_blk);
311                 return NULL;
312         }
313
314         if (bitmap_uptodate(bh))
315                 return bh;
316
317         lock_buffer(bh);
318         if (bitmap_uptodate(bh)) {
319                 unlock_buffer(bh);
320                 return bh;
321         }
322         ext4_lock_group(sb, block_group);
323         if (desc->bg_flags & cpu_to_le16(EXT4_BG_BLOCK_UNINIT)) {
324                 ext4_init_block_bitmap(sb, bh, block_group, desc);
325                 set_bitmap_uptodate(bh);
326                 set_buffer_uptodate(bh);
327                 ext4_unlock_group(sb, block_group);
328                 unlock_buffer(bh);
329                 return bh;
330         }
331         ext4_unlock_group(sb, block_group);
332         if (buffer_uptodate(bh)) {
333                 /*
334                  * if not uninit if bh is uptodate,
335                  * bitmap is also uptodate
336                  */
337                 set_bitmap_uptodate(bh);
338                 unlock_buffer(bh);
339                 return bh;
340         }
341         /*
342          * submit the buffer_head for read. We can
343          * safely mark the bitmap as uptodate now.
344          * We do it here so the bitmap uptodate bit
345          * get set with buffer lock held.
346          */
347         trace_ext4_read_block_bitmap_load(sb, block_group);
348         set_bitmap_uptodate(bh);
349         if (bh_submit_read(bh) < 0) {
350                 put_bh(bh);
351                 ext4_error(sb, "Cannot read block bitmap - "
352                             "block_group = %u, block_bitmap = %llu",
353                             block_group, bitmap_blk);
354                 return NULL;
355         }
356         ext4_valid_block_bitmap(sb, desc, block_group, bh);
357         /*
358          * file system mounted not to panic on error,
359          * continue with corrupt bitmap
360          */
361         return bh;
362 }
363
364 /**
365  * ext4_add_groupblocks() -- Add given blocks to an existing group
366  * @handle:                     handle to this transaction
367  * @sb:                         super block
368  * @block:                      start physcial block to add to the block group
369  * @count:                      number of blocks to free
370  *
371  * This marks the blocks as free in the bitmap. We ask the
372  * mballoc to reload the buddy after this by setting group
373  * EXT4_GROUP_INFO_NEED_INIT_BIT flag
374  */
375 void ext4_add_groupblocks(handle_t *handle, struct super_block *sb,
376                          ext4_fsblk_t block, unsigned long count)
377 {
378         struct buffer_head *bitmap_bh = NULL;
379         struct buffer_head *gd_bh;
380         ext4_group_t block_group;
381         ext4_grpblk_t bit;
382         unsigned int i;
383         struct ext4_group_desc *desc;
384         struct ext4_sb_info *sbi = EXT4_SB(sb);
385         int err = 0, ret, blk_free_count;
386         ext4_grpblk_t blocks_freed;
387         struct ext4_group_info *grp;
388
389         ext4_debug("Adding block(s) %llu-%llu\n", block, block + count - 1);
390
391         ext4_get_group_no_and_offset(sb, block, &block_group, &bit);
392         grp = ext4_get_group_info(sb, block_group);
393         /*
394          * Check to see if we are freeing blocks across a group
395          * boundary.
396          */
397         if (bit + count > EXT4_BLOCKS_PER_GROUP(sb)) {
398                 goto error_return;
399         }
400         bitmap_bh = ext4_read_block_bitmap(sb, block_group);
401         if (!bitmap_bh)
402                 goto error_return;
403         desc = ext4_get_group_desc(sb, block_group, &gd_bh);
404         if (!desc)
405                 goto error_return;
406
407         if (in_range(ext4_block_bitmap(sb, desc), block, count) ||
408             in_range(ext4_inode_bitmap(sb, desc), block, count) ||
409             in_range(block, ext4_inode_table(sb, desc), sbi->s_itb_per_group) ||
410             in_range(block + count - 1, ext4_inode_table(sb, desc),
411                      sbi->s_itb_per_group)) {
412                 ext4_error(sb, "Adding blocks in system zones - "
413                            "Block = %llu, count = %lu",
414                            block, count);
415                 goto error_return;
416         }
417
418         /*
419          * We are about to add blocks to the bitmap,
420          * so we need undo access.
421          */
422         BUFFER_TRACE(bitmap_bh, "getting undo access");
423         err = ext4_journal_get_undo_access(handle, bitmap_bh);
424         if (err)
425                 goto error_return;
426
427         /*
428          * We are about to modify some metadata.  Call the journal APIs
429          * to unshare ->b_data if a currently-committing transaction is
430          * using it
431          */
432         BUFFER_TRACE(gd_bh, "get_write_access");
433         err = ext4_journal_get_write_access(handle, gd_bh);
434         if (err)
435                 goto error_return;
436         /*
437          * make sure we don't allow a parallel init on other groups in the
438          * same buddy cache
439          */
440         down_write(&grp->alloc_sem);
441         for (i = 0, blocks_freed = 0; i < count; i++) {
442                 BUFFER_TRACE(bitmap_bh, "clear bit");
443                 if (!ext4_clear_bit_atomic(ext4_group_lock_ptr(sb, block_group),
444                                                 bit + i, bitmap_bh->b_data)) {
445                         ext4_error(sb, "bit already cleared for block %llu",
446                                    (ext4_fsblk_t)(block + i));
447                         BUFFER_TRACE(bitmap_bh, "bit already cleared");
448                 } else {
449                         blocks_freed++;
450                 }
451         }
452         ext4_lock_group(sb, block_group);
453         blk_free_count = blocks_freed + ext4_free_blks_count(sb, desc);
454         ext4_free_blks_set(sb, desc, blk_free_count);
455         desc->bg_checksum = ext4_group_desc_csum(sbi, block_group, desc);
456         ext4_unlock_group(sb, block_group);
457         percpu_counter_add(&sbi->s_freeblocks_counter, blocks_freed);
458
459         if (sbi->s_log_groups_per_flex) {
460                 ext4_group_t flex_group = ext4_flex_group(sbi, block_group);
461                 atomic_add(blocks_freed,
462                            &sbi->s_flex_groups[flex_group].free_blocks);
463         }
464         /*
465          * request to reload the buddy with the
466          * new bitmap information
467          */
468         set_bit(EXT4_GROUP_INFO_NEED_INIT_BIT, &(grp->bb_state));
469         grp->bb_free += blocks_freed;
470         up_write(&grp->alloc_sem);
471
472         /* We dirtied the bitmap block */
473         BUFFER_TRACE(bitmap_bh, "dirtied bitmap block");
474         err = ext4_handle_dirty_metadata(handle, NULL, bitmap_bh);
475
476         /* And the group descriptor block */
477         BUFFER_TRACE(gd_bh, "dirtied group descriptor block");
478         ret = ext4_handle_dirty_metadata(handle, NULL, gd_bh);
479         if (!err)
480                 err = ret;
481
482 error_return:
483         brelse(bitmap_bh);
484         ext4_std_error(sb, err);
485         return;
486 }
487
488 /**
489  * ext4_has_free_blocks()
490  * @sbi:        in-core super block structure.
491  * @nblocks:    number of needed blocks
492  *
493  * Check if filesystem has nblocks free & available for allocation.
494  * On success return 1, return 0 on failure.
495  */
496 static int ext4_has_free_blocks(struct ext4_sb_info *sbi, s64 nblocks)
497 {
498         s64 free_blocks, dirty_blocks, root_blocks;
499         struct percpu_counter *fbc = &sbi->s_freeblocks_counter;
500         struct percpu_counter *dbc = &sbi->s_dirtyblocks_counter;
501
502         free_blocks  = percpu_counter_read_positive(fbc);
503         dirty_blocks = percpu_counter_read_positive(dbc);
504         root_blocks = ext4_r_blocks_count(sbi->s_es);
505
506         if (free_blocks - (nblocks + root_blocks + dirty_blocks) <
507                                                 EXT4_FREEBLOCKS_WATERMARK) {
508                 free_blocks  = percpu_counter_sum_positive(fbc);
509                 dirty_blocks = percpu_counter_sum_positive(dbc);
510                 if (dirty_blocks < 0) {
511                         printk(KERN_CRIT "Dirty block accounting "
512                                         "went wrong %lld\n",
513                                         (long long)dirty_blocks);
514                 }
515         }
516         /* Check whether we have space after
517          * accounting for current dirty blocks & root reserved blocks.
518          */
519         if (free_blocks >= ((root_blocks + nblocks) + dirty_blocks))
520                 return 1;
521
522         /* Hm, nope.  Are (enough) root reserved blocks available? */
523         if (sbi->s_resuid == current_fsuid() ||
524             ((sbi->s_resgid != 0) && in_group_p(sbi->s_resgid)) ||
525             capable(CAP_SYS_RESOURCE)) {
526                 if (free_blocks >= (nblocks + dirty_blocks))
527                         return 1;
528         }
529
530         return 0;
531 }
532
533 int ext4_claim_free_blocks(struct ext4_sb_info *sbi,
534                                                 s64 nblocks)
535 {
536         if (ext4_has_free_blocks(sbi, nblocks)) {
537                 percpu_counter_add(&sbi->s_dirtyblocks_counter, nblocks);
538                 return 0;
539         } else
540                 return -ENOSPC;
541 }
542
543 /**
544  * ext4_should_retry_alloc()
545  * @sb:                 super block
546  * @retries             number of attemps has been made
547  *
548  * ext4_should_retry_alloc() is called when ENOSPC is returned, and if
549  * it is profitable to retry the operation, this function will wait
550  * for the current or committing transaction to complete, and then
551  * return TRUE.
552  *
553  * if the total number of retries exceed three times, return FALSE.
554  */
555 int ext4_should_retry_alloc(struct super_block *sb, int *retries)
556 {
557         if (!ext4_has_free_blocks(EXT4_SB(sb), 1) ||
558             (*retries)++ > 3 ||
559             !EXT4_SB(sb)->s_journal)
560                 return 0;
561
562         jbd_debug(1, "%s: retrying operation after ENOSPC\n", sb->s_id);
563
564         return jbd2_journal_force_commit_nested(EXT4_SB(sb)->s_journal);
565 }
566
567 /*
568  * ext4_new_meta_blocks() -- allocate block for meta data (indexing) blocks
569  *
570  * @handle:             handle to this transaction
571  * @inode:              file inode
572  * @goal:               given target block(filesystem wide)
573  * @count:              pointer to total number of blocks needed
574  * @errp:               error code
575  *
576  * Return 1st allocated block number on success, *count stores total account
577  * error stores in errp pointer
578  */
579 ext4_fsblk_t ext4_new_meta_blocks(handle_t *handle, struct inode *inode,
580                 ext4_fsblk_t goal, unsigned long *count, int *errp)
581 {
582         struct ext4_allocation_request ar;
583         ext4_fsblk_t ret;
584
585         memset(&ar, 0, sizeof(ar));
586         /* Fill with neighbour allocated blocks */
587         ar.inode = inode;
588         ar.goal = goal;
589         ar.len = count ? *count : 1;
590
591         ret = ext4_mb_new_blocks(handle, &ar, errp);
592         if (count)
593                 *count = ar.len;
594         /*
595          * Account for the allocated meta blocks.  We will never
596          * fail EDQUOT for metdata, but we do account for it.
597          */
598         if (!(*errp) &&
599             ext4_test_inode_state(inode, EXT4_STATE_DELALLOC_RESERVED)) {
600                 spin_lock(&EXT4_I(inode)->i_block_reservation_lock);
601                 EXT4_I(inode)->i_allocated_meta_blocks += ar.len;
602                 spin_unlock(&EXT4_I(inode)->i_block_reservation_lock);
603                 dquot_alloc_block_nofail(inode, ar.len);
604         }
605         return ret;
606 }
607
608 /**
609  * ext4_count_free_blocks() -- count filesystem free blocks
610  * @sb:         superblock
611  *
612  * Adds up the number of free blocks from each block group.
613  */
614 ext4_fsblk_t ext4_count_free_blocks(struct super_block *sb)
615 {
616         ext4_fsblk_t desc_count;
617         struct ext4_group_desc *gdp;
618         ext4_group_t i;
619         ext4_group_t ngroups = ext4_get_groups_count(sb);
620 #ifdef EXT4FS_DEBUG
621         struct ext4_super_block *es;
622         ext4_fsblk_t bitmap_count;
623         unsigned int x;
624         struct buffer_head *bitmap_bh = NULL;
625
626         es = EXT4_SB(sb)->s_es;
627         desc_count = 0;
628         bitmap_count = 0;
629         gdp = NULL;
630
631         for (i = 0; i < ngroups; i++) {
632                 gdp = ext4_get_group_desc(sb, i, NULL);
633                 if (!gdp)
634                         continue;
635                 desc_count += ext4_free_blks_count(sb, gdp);
636                 brelse(bitmap_bh);
637                 bitmap_bh = ext4_read_block_bitmap(sb, i);
638                 if (bitmap_bh == NULL)
639                         continue;
640
641                 x = ext4_count_free(bitmap_bh, sb->s_blocksize);
642                 printk(KERN_DEBUG "group %u: stored = %d, counted = %u\n",
643                         i, ext4_free_blks_count(sb, gdp), x);
644                 bitmap_count += x;
645         }
646         brelse(bitmap_bh);
647         printk(KERN_DEBUG "ext4_count_free_blocks: stored = %llu"
648                 ", computed = %llu, %llu\n", ext4_free_blocks_count(es),
649                desc_count, bitmap_count);
650         return bitmap_count;
651 #else
652         desc_count = 0;
653         for (i = 0; i < ngroups; i++) {
654                 gdp = ext4_get_group_desc(sb, i, NULL);
655                 if (!gdp)
656                         continue;
657                 desc_count += ext4_free_blks_count(sb, gdp);
658         }
659
660         return desc_count;
661 #endif
662 }
663
664 static inline int test_root(ext4_group_t a, int b)
665 {
666         int num = b;
667
668         while (a > num)
669                 num *= b;
670         return num == a;
671 }
672
673 static int ext4_group_sparse(ext4_group_t group)
674 {
675         if (group <= 1)
676                 return 1;
677         if (!(group & 1))
678                 return 0;
679         return (test_root(group, 7) || test_root(group, 5) ||
680                 test_root(group, 3));
681 }
682
683 /**
684  *      ext4_bg_has_super - number of blocks used by the superblock in group
685  *      @sb: superblock for filesystem
686  *      @group: group number to check
687  *
688  *      Return the number of blocks used by the superblock (primary or backup)
689  *      in this group.  Currently this will be only 0 or 1.
690  */
691 int ext4_bg_has_super(struct super_block *sb, ext4_group_t group)
692 {
693         if (EXT4_HAS_RO_COMPAT_FEATURE(sb,
694                                 EXT4_FEATURE_RO_COMPAT_SPARSE_SUPER) &&
695                         !ext4_group_sparse(group))
696                 return 0;
697         return 1;
698 }
699
700 static unsigned long ext4_bg_num_gdb_meta(struct super_block *sb,
701                                         ext4_group_t group)
702 {
703         unsigned long metagroup = group / EXT4_DESC_PER_BLOCK(sb);
704         ext4_group_t first = metagroup * EXT4_DESC_PER_BLOCK(sb);
705         ext4_group_t last = first + EXT4_DESC_PER_BLOCK(sb) - 1;
706
707         if (group == first || group == first + 1 || group == last)
708                 return 1;
709         return 0;
710 }
711
712 static unsigned long ext4_bg_num_gdb_nometa(struct super_block *sb,
713                                         ext4_group_t group)
714 {
715         if (!ext4_bg_has_super(sb, group))
716                 return 0;
717
718         if (EXT4_HAS_INCOMPAT_FEATURE(sb,EXT4_FEATURE_INCOMPAT_META_BG))
719                 return le32_to_cpu(EXT4_SB(sb)->s_es->s_first_meta_bg);
720         else
721                 return EXT4_SB(sb)->s_gdb_count;
722 }
723
724 /**
725  *      ext4_bg_num_gdb - number of blocks used by the group table in group
726  *      @sb: superblock for filesystem
727  *      @group: group number to check
728  *
729  *      Return the number of blocks used by the group descriptor table
730  *      (primary or backup) in this group.  In the future there may be a
731  *      different number of descriptor blocks in each group.
732  */
733 unsigned long ext4_bg_num_gdb(struct super_block *sb, ext4_group_t group)
734 {
735         unsigned long first_meta_bg =
736                         le32_to_cpu(EXT4_SB(sb)->s_es->s_first_meta_bg);
737         unsigned long metagroup = group / EXT4_DESC_PER_BLOCK(sb);
738
739         if (!EXT4_HAS_INCOMPAT_FEATURE(sb,EXT4_FEATURE_INCOMPAT_META_BG) ||
740                         metagroup < first_meta_bg)
741                 return ext4_bg_num_gdb_nometa(sb, group);
742
743         return ext4_bg_num_gdb_meta(sb,group);
744
745 }
746