ext4: move __func__ into a macro for ext4_warning, ext4_error
[linux-2.6.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 /*
25  * balloc.c contains the blocks allocation and deallocation routines
26  */
27
28 /*
29  * Calculate the block group number and offset, given a block number
30  */
31 void ext4_get_group_no_and_offset(struct super_block *sb, ext4_fsblk_t blocknr,
32                 ext4_group_t *blockgrpp, ext4_grpblk_t *offsetp)
33 {
34         struct ext4_super_block *es = EXT4_SB(sb)->s_es;
35         ext4_grpblk_t offset;
36
37         blocknr = blocknr - le32_to_cpu(es->s_first_data_block);
38         offset = do_div(blocknr, EXT4_BLOCKS_PER_GROUP(sb));
39         if (offsetp)
40                 *offsetp = offset;
41         if (blockgrpp)
42                 *blockgrpp = blocknr;
43
44 }
45
46 static int ext4_block_in_group(struct super_block *sb, ext4_fsblk_t block,
47                         ext4_group_t block_group)
48 {
49         ext4_group_t actual_group;
50         ext4_get_group_no_and_offset(sb, block, &actual_group, NULL);
51         if (actual_group == block_group)
52                 return 1;
53         return 0;
54 }
55
56 static int ext4_group_used_meta_blocks(struct super_block *sb,
57                                        ext4_group_t block_group,
58                                        struct ext4_group_desc *gdp)
59 {
60         ext4_fsblk_t tmp;
61         struct ext4_sb_info *sbi = EXT4_SB(sb);
62         /* block bitmap, inode bitmap, and inode table blocks */
63         int used_blocks = sbi->s_itb_per_group + 2;
64
65         if (EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_FLEX_BG)) {
66                 if (!ext4_block_in_group(sb, ext4_block_bitmap(sb, gdp),
67                                         block_group))
68                         used_blocks--;
69
70                 if (!ext4_block_in_group(sb, ext4_inode_bitmap(sb, gdp),
71                                         block_group))
72                         used_blocks--;
73
74                 tmp = ext4_inode_table(sb, gdp);
75                 for (; tmp < ext4_inode_table(sb, gdp) +
76                                 sbi->s_itb_per_group; tmp++) {
77                         if (!ext4_block_in_group(sb, tmp, block_group))
78                                 used_blocks -= 1;
79                 }
80         }
81         return used_blocks;
82 }
83
84 /* Initializes an uninitialized block bitmap if given, and returns the
85  * number of blocks free in the group. */
86 unsigned ext4_init_block_bitmap(struct super_block *sb, struct buffer_head *bh,
87                  ext4_group_t block_group, struct ext4_group_desc *gdp)
88 {
89         int bit, bit_max;
90         ext4_group_t ngroups = ext4_get_groups_count(sb);
91         unsigned free_blocks, group_blocks;
92         struct ext4_sb_info *sbi = EXT4_SB(sb);
93
94         if (bh) {
95                 J_ASSERT_BH(bh, buffer_locked(bh));
96
97                 /* If checksum is bad mark all blocks used to prevent allocation
98                  * essentially implementing a per-group read-only flag. */
99                 if (!ext4_group_desc_csum_verify(sbi, block_group, gdp)) {
100                         ext4_error(sb, "Checksum bad for group %u",
101                                         block_group);
102                         ext4_free_blks_set(sb, gdp, 0);
103                         ext4_free_inodes_set(sb, gdp, 0);
104                         ext4_itable_unused_set(sb, gdp, 0);
105                         memset(bh->b_data, 0xff, sb->s_blocksize);
106                         return 0;
107                 }
108                 memset(bh->b_data, 0, sb->s_blocksize);
109         }
110
111         /* Check for superblock and gdt backups in this group */
112         bit_max = ext4_bg_has_super(sb, block_group);
113
114         if (!EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_META_BG) ||
115             block_group < le32_to_cpu(sbi->s_es->s_first_meta_bg) *
116                           sbi->s_desc_per_block) {
117                 if (bit_max) {
118                         bit_max += ext4_bg_num_gdb(sb, block_group);
119                         bit_max +=
120                                 le16_to_cpu(sbi->s_es->s_reserved_gdt_blocks);
121                 }
122         } else { /* For META_BG_BLOCK_GROUPS */
123                 bit_max += ext4_bg_num_gdb(sb, block_group);
124         }
125
126         if (block_group == ngroups - 1) {
127                 /*
128                  * Even though mke2fs always initialize first and last group
129                  * if some other tool enabled the EXT4_BG_BLOCK_UNINIT we need
130                  * to make sure we calculate the right free blocks
131                  */
132                 group_blocks = ext4_blocks_count(sbi->s_es) -
133                         le32_to_cpu(sbi->s_es->s_first_data_block) -
134                         (EXT4_BLOCKS_PER_GROUP(sb) * (ngroups - 1));
135         } else {
136                 group_blocks = EXT4_BLOCKS_PER_GROUP(sb);
137         }
138
139         free_blocks = group_blocks - bit_max;
140
141         if (bh) {
142                 ext4_fsblk_t start, tmp;
143                 int flex_bg = 0;
144
145                 for (bit = 0; bit < bit_max; bit++)
146                         ext4_set_bit(bit, bh->b_data);
147
148                 start = ext4_group_first_block_no(sb, block_group);
149
150                 if (EXT4_HAS_INCOMPAT_FEATURE(sb,
151                                               EXT4_FEATURE_INCOMPAT_FLEX_BG))
152                         flex_bg = 1;
153
154                 /* Set bits for block and inode bitmaps, and inode table */
155                 tmp = ext4_block_bitmap(sb, gdp);
156                 if (!flex_bg || ext4_block_in_group(sb, tmp, block_group))
157                         ext4_set_bit(tmp - start, bh->b_data);
158
159                 tmp = ext4_inode_bitmap(sb, gdp);
160                 if (!flex_bg || ext4_block_in_group(sb, tmp, block_group))
161                         ext4_set_bit(tmp - start, bh->b_data);
162
163                 tmp = ext4_inode_table(sb, gdp);
164                 for (; tmp < ext4_inode_table(sb, gdp) +
165                                 sbi->s_itb_per_group; tmp++) {
166                         if (!flex_bg ||
167                                 ext4_block_in_group(sb, tmp, block_group))
168                                 ext4_set_bit(tmp - start, bh->b_data);
169                 }
170                 /*
171                  * Also if the number of blocks within the group is
172                  * less than the blocksize * 8 ( which is the size
173                  * of bitmap ), set rest of the block bitmap to 1
174                  */
175                 mark_bitmap_end(group_blocks, sb->s_blocksize * 8, bh->b_data);
176         }
177         return free_blocks - ext4_group_used_meta_blocks(sb, block_group, gdp);
178 }
179
180
181 /*
182  * The free blocks are managed by bitmaps.  A file system contains several
183  * blocks groups.  Each group contains 1 bitmap block for blocks, 1 bitmap
184  * block for inodes, N blocks for the inode table and data blocks.
185  *
186  * The file system contains group descriptors which are located after the
187  * super block.  Each descriptor contains the number of the bitmap block and
188  * the free blocks count in the block.  The descriptors are loaded in memory
189  * when a file system is mounted (see ext4_fill_super).
190  */
191
192
193 #define in_range(b, first, len) ((b) >= (first) && (b) <= (first) + (len) - 1)
194
195 /**
196  * ext4_get_group_desc() -- load group descriptor from disk
197  * @sb:                 super block
198  * @block_group:        given block group
199  * @bh:                 pointer to the buffer head to store the block
200  *                      group descriptor
201  */
202 struct ext4_group_desc * ext4_get_group_desc(struct super_block *sb,
203                                              ext4_group_t block_group,
204                                              struct buffer_head **bh)
205 {
206         unsigned int group_desc;
207         unsigned int offset;
208         ext4_group_t ngroups = ext4_get_groups_count(sb);
209         struct ext4_group_desc *desc;
210         struct ext4_sb_info *sbi = EXT4_SB(sb);
211
212         if (block_group >= ngroups) {
213                 ext4_error(sb, "block_group >= groups_count - block_group = %u,"
214                            " groups_count = %u", block_group, ngroups);
215
216                 return NULL;
217         }
218
219         group_desc = block_group >> EXT4_DESC_PER_BLOCK_BITS(sb);
220         offset = block_group & (EXT4_DESC_PER_BLOCK(sb) - 1);
221         if (!sbi->s_group_desc[group_desc]) {
222                 ext4_error(sb, "Group descriptor not loaded - "
223                            "block_group = %u, group_desc = %u, desc = %u",
224                            block_group, group_desc, offset);
225                 return NULL;
226         }
227
228         desc = (struct ext4_group_desc *)(
229                 (__u8 *)sbi->s_group_desc[group_desc]->b_data +
230                 offset * EXT4_DESC_SIZE(sb));
231         if (bh)
232                 *bh = sbi->s_group_desc[group_desc];
233         return desc;
234 }
235
236 static int ext4_valid_block_bitmap(struct super_block *sb,
237                                         struct ext4_group_desc *desc,
238                                         unsigned int block_group,
239                                         struct buffer_head *bh)
240 {
241         ext4_grpblk_t offset;
242         ext4_grpblk_t next_zero_bit;
243         ext4_fsblk_t bitmap_blk;
244         ext4_fsblk_t group_first_block;
245
246         if (EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_FLEX_BG)) {
247                 /* with FLEX_BG, the inode/block bitmaps and itable
248                  * blocks may not be in the group at all
249                  * so the bitmap validation will be skipped for those groups
250                  * or it has to also read the block group where the bitmaps
251                  * are located to verify they are set.
252                  */
253                 return 1;
254         }
255         group_first_block = ext4_group_first_block_no(sb, block_group);
256
257         /* check whether block bitmap block number is set */
258         bitmap_blk = ext4_block_bitmap(sb, desc);
259         offset = bitmap_blk - group_first_block;
260         if (!ext4_test_bit(offset, bh->b_data))
261                 /* bad block bitmap */
262                 goto err_out;
263
264         /* check whether the inode bitmap block number is set */
265         bitmap_blk = ext4_inode_bitmap(sb, desc);
266         offset = bitmap_blk - group_first_block;
267         if (!ext4_test_bit(offset, bh->b_data))
268                 /* bad block bitmap */
269                 goto err_out;
270
271         /* check whether the inode table block number is set */
272         bitmap_blk = ext4_inode_table(sb, desc);
273         offset = bitmap_blk - group_first_block;
274         next_zero_bit = ext4_find_next_zero_bit(bh->b_data,
275                                 offset + EXT4_SB(sb)->s_itb_per_group,
276                                 offset);
277         if (next_zero_bit >= offset + EXT4_SB(sb)->s_itb_per_group)
278                 /* good bitmap for inode tables */
279                 return 1;
280
281 err_out:
282         ext4_error(sb, "Invalid block bitmap - block_group = %d, block = %llu",
283                         block_group, bitmap_blk);
284         return 0;
285 }
286 /**
287  * ext4_read_block_bitmap()
288  * @sb:                 super block
289  * @block_group:        given block group
290  *
291  * Read the bitmap for a given block_group,and validate the
292  * bits for block/inode/inode tables are set in the bitmaps
293  *
294  * Return buffer_head on success or NULL in case of failure.
295  */
296 struct buffer_head *
297 ext4_read_block_bitmap(struct super_block *sb, ext4_group_t block_group)
298 {
299         struct ext4_group_desc *desc;
300         struct buffer_head *bh = NULL;
301         ext4_fsblk_t bitmap_blk;
302
303         desc = ext4_get_group_desc(sb, block_group, NULL);
304         if (!desc)
305                 return NULL;
306         bitmap_blk = ext4_block_bitmap(sb, desc);
307         bh = sb_getblk(sb, bitmap_blk);
308         if (unlikely(!bh)) {
309                 ext4_error(sb, "Cannot read block bitmap - "
310                             "block_group = %u, block_bitmap = %llu",
311                             block_group, bitmap_blk);
312                 return NULL;
313         }
314
315         if (bitmap_uptodate(bh))
316                 return bh;
317
318         lock_buffer(bh);
319         if (bitmap_uptodate(bh)) {
320                 unlock_buffer(bh);
321                 return bh;
322         }
323         ext4_lock_group(sb, block_group);
324         if (desc->bg_flags & cpu_to_le16(EXT4_BG_BLOCK_UNINIT)) {
325                 ext4_init_block_bitmap(sb, bh, block_group, desc);
326                 set_bitmap_uptodate(bh);
327                 set_buffer_uptodate(bh);
328                 ext4_unlock_group(sb, block_group);
329                 unlock_buffer(bh);
330                 return bh;
331         }
332         ext4_unlock_group(sb, block_group);
333         if (buffer_uptodate(bh)) {
334                 /*
335                  * if not uninit if bh is uptodate,
336                  * bitmap is also uptodate
337                  */
338                 set_bitmap_uptodate(bh);
339                 unlock_buffer(bh);
340                 return bh;
341         }
342         /*
343          * submit the buffer_head for read. We can
344          * safely mark the bitmap as uptodate now.
345          * We do it here so the bitmap uptodate bit
346          * get set with buffer lock held.
347          */
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_super_block *es;
385         struct ext4_sb_info *sbi;
386         int err = 0, ret, blk_free_count;
387         ext4_grpblk_t blocks_freed;
388         struct ext4_group_info *grp;
389
390         sbi = EXT4_SB(sb);
391         es = sbi->s_es;
392         ext4_debug("Adding block(s) %llu-%llu\n", block, block + count - 1);
393
394         ext4_get_group_no_and_offset(sb, block, &block_group, &bit);
395         grp = ext4_get_group_info(sb, block_group);
396         /*
397          * Check to see if we are freeing blocks across a group
398          * boundary.
399          */
400         if (bit + count > EXT4_BLOCKS_PER_GROUP(sb)) {
401                 goto error_return;
402         }
403         bitmap_bh = ext4_read_block_bitmap(sb, block_group);
404         if (!bitmap_bh)
405                 goto error_return;
406         desc = ext4_get_group_desc(sb, block_group, &gd_bh);
407         if (!desc)
408                 goto error_return;
409
410         if (in_range(ext4_block_bitmap(sb, desc), block, count) ||
411             in_range(ext4_inode_bitmap(sb, desc), block, count) ||
412             in_range(block, ext4_inode_table(sb, desc), sbi->s_itb_per_group) ||
413             in_range(block + count - 1, ext4_inode_table(sb, desc),
414                      sbi->s_itb_per_group)) {
415                 ext4_error(sb, "Adding blocks in system zones - "
416                            "Block = %llu, count = %lu",
417                            block, count);
418                 goto error_return;
419         }
420
421         /*
422          * We are about to add blocks to the bitmap,
423          * so we need undo access.
424          */
425         BUFFER_TRACE(bitmap_bh, "getting undo access");
426         err = ext4_journal_get_undo_access(handle, bitmap_bh);
427         if (err)
428                 goto error_return;
429
430         /*
431          * We are about to modify some metadata.  Call the journal APIs
432          * to unshare ->b_data if a currently-committing transaction is
433          * using it
434          */
435         BUFFER_TRACE(gd_bh, "get_write_access");
436         err = ext4_journal_get_write_access(handle, gd_bh);
437         if (err)
438                 goto error_return;
439         /*
440          * make sure we don't allow a parallel init on other groups in the
441          * same buddy cache
442          */
443         down_write(&grp->alloc_sem);
444         for (i = 0, blocks_freed = 0; i < count; i++) {
445                 BUFFER_TRACE(bitmap_bh, "clear bit");
446                 if (!ext4_clear_bit_atomic(ext4_group_lock_ptr(sb, block_group),
447                                                 bit + i, bitmap_bh->b_data)) {
448                         ext4_error(sb, "bit already cleared for block %llu",
449                                    (ext4_fsblk_t)(block + i));
450                         BUFFER_TRACE(bitmap_bh, "bit already cleared");
451                 } else {
452                         blocks_freed++;
453                 }
454         }
455         ext4_lock_group(sb, block_group);
456         blk_free_count = blocks_freed + ext4_free_blks_count(sb, desc);
457         ext4_free_blks_set(sb, desc, blk_free_count);
458         desc->bg_checksum = ext4_group_desc_csum(sbi, block_group, desc);
459         ext4_unlock_group(sb, block_group);
460         percpu_counter_add(&sbi->s_freeblocks_counter, blocks_freed);
461
462         if (sbi->s_log_groups_per_flex) {
463                 ext4_group_t flex_group = ext4_flex_group(sbi, block_group);
464                 atomic_add(blocks_freed,
465                            &sbi->s_flex_groups[flex_group].free_blocks);
466         }
467         /*
468          * request to reload the buddy with the
469          * new bitmap information
470          */
471         set_bit(EXT4_GROUP_INFO_NEED_INIT_BIT, &(grp->bb_state));
472         grp->bb_free += blocks_freed;
473         up_write(&grp->alloc_sem);
474
475         /* We dirtied the bitmap block */
476         BUFFER_TRACE(bitmap_bh, "dirtied bitmap block");
477         err = ext4_handle_dirty_metadata(handle, NULL, bitmap_bh);
478
479         /* And the group descriptor block */
480         BUFFER_TRACE(gd_bh, "dirtied group descriptor block");
481         ret = ext4_handle_dirty_metadata(handle, NULL, gd_bh);
482         if (!err)
483                 err = ret;
484         sb->s_dirt = 1;
485
486 error_return:
487         brelse(bitmap_bh);
488         ext4_std_error(sb, err);
489         return;
490 }
491
492 /**
493  * ext4_has_free_blocks()
494  * @sbi:        in-core super block structure.
495  * @nblocks:    number of needed blocks
496  *
497  * Check if filesystem has nblocks free & available for allocation.
498  * On success return 1, return 0 on failure.
499  */
500 int ext4_has_free_blocks(struct ext4_sb_info *sbi, s64 nblocks)
501 {
502         s64 free_blocks, dirty_blocks, root_blocks;
503         struct percpu_counter *fbc = &sbi->s_freeblocks_counter;
504         struct percpu_counter *dbc = &sbi->s_dirtyblocks_counter;
505
506         free_blocks  = percpu_counter_read_positive(fbc);
507         dirty_blocks = percpu_counter_read_positive(dbc);
508         root_blocks = ext4_r_blocks_count(sbi->s_es);
509
510         if (free_blocks - (nblocks + root_blocks + dirty_blocks) <
511                                                 EXT4_FREEBLOCKS_WATERMARK) {
512                 free_blocks  = percpu_counter_sum_positive(fbc);
513                 dirty_blocks = percpu_counter_sum_positive(dbc);
514                 if (dirty_blocks < 0) {
515                         printk(KERN_CRIT "Dirty block accounting "
516                                         "went wrong %lld\n",
517                                         (long long)dirty_blocks);
518                 }
519         }
520         /* Check whether we have space after
521          * accounting for current dirty blocks & root reserved blocks.
522          */
523         if (free_blocks >= ((root_blocks + nblocks) + dirty_blocks))
524                 return 1;
525
526         /* Hm, nope.  Are (enough) root reserved blocks available? */
527         if (sbi->s_resuid == current_fsuid() ||
528             ((sbi->s_resgid != 0) && in_group_p(sbi->s_resgid)) ||
529             capable(CAP_SYS_RESOURCE)) {
530                 if (free_blocks >= (nblocks + dirty_blocks))
531                         return 1;
532         }
533
534         return 0;
535 }
536
537 int ext4_claim_free_blocks(struct ext4_sb_info *sbi,
538                                                 s64 nblocks)
539 {
540         if (ext4_has_free_blocks(sbi, nblocks)) {
541                 percpu_counter_add(&sbi->s_dirtyblocks_counter, nblocks);
542                 return 0;
543         } else
544                 return -ENOSPC;
545 }
546
547 /**
548  * ext4_should_retry_alloc()
549  * @sb:                 super block
550  * @retries             number of attemps has been made
551  *
552  * ext4_should_retry_alloc() is called when ENOSPC is returned, and if
553  * it is profitable to retry the operation, this function will wait
554  * for the current or commiting transaction to complete, and then
555  * return TRUE.
556  *
557  * if the total number of retries exceed three times, return FALSE.
558  */
559 int ext4_should_retry_alloc(struct super_block *sb, int *retries)
560 {
561         if (!ext4_has_free_blocks(EXT4_SB(sb), 1) ||
562             (*retries)++ > 3 ||
563             !EXT4_SB(sb)->s_journal)
564                 return 0;
565
566         jbd_debug(1, "%s: retrying operation after ENOSPC\n", sb->s_id);
567
568         return jbd2_journal_force_commit_nested(EXT4_SB(sb)->s_journal);
569 }
570
571 /*
572  * ext4_new_meta_blocks() -- allocate block for meta data (indexing) blocks
573  *
574  * @handle:             handle to this transaction
575  * @inode:              file inode
576  * @goal:               given target block(filesystem wide)
577  * @count:              pointer to total number of blocks needed
578  * @errp:               error code
579  *
580  * Return 1st allocated block number on success, *count stores total account
581  * error stores in errp pointer
582  */
583 ext4_fsblk_t ext4_new_meta_blocks(handle_t *handle, struct inode *inode,
584                 ext4_fsblk_t goal, unsigned long *count, int *errp)
585 {
586         struct ext4_allocation_request ar;
587         ext4_fsblk_t ret;
588
589         memset(&ar, 0, sizeof(ar));
590         /* Fill with neighbour allocated blocks */
591         ar.inode = inode;
592         ar.goal = goal;
593         ar.len = count ? *count : 1;
594
595         ret = ext4_mb_new_blocks(handle, &ar, errp);
596         if (count)
597                 *count = ar.len;
598
599         /*
600          * Account for the allocated meta blocks
601          */
602         if (!(*errp) && EXT4_I(inode)->i_delalloc_reserved_flag) {
603                 spin_lock(&EXT4_I(inode)->i_block_reservation_lock);
604                 EXT4_I(inode)->i_allocated_meta_blocks += ar.len;
605                 spin_unlock(&EXT4_I(inode)->i_block_reservation_lock);
606         }
607         return ret;
608 }
609
610 /**
611  * ext4_count_free_blocks() -- count filesystem free blocks
612  * @sb:         superblock
613  *
614  * Adds up the number of free blocks from each block group.
615  */
616 ext4_fsblk_t ext4_count_free_blocks(struct super_block *sb)
617 {
618         ext4_fsblk_t desc_count;
619         struct ext4_group_desc *gdp;
620         ext4_group_t i;
621         ext4_group_t ngroups = ext4_get_groups_count(sb);
622 #ifdef EXT4FS_DEBUG
623         struct ext4_super_block *es;
624         ext4_fsblk_t bitmap_count;
625         unsigned int x;
626         struct buffer_head *bitmap_bh = NULL;
627
628         es = EXT4_SB(sb)->s_es;
629         desc_count = 0;
630         bitmap_count = 0;
631         gdp = NULL;
632
633         for (i = 0; i < ngroups; i++) {
634                 gdp = ext4_get_group_desc(sb, i, NULL);
635                 if (!gdp)
636                         continue;
637                 desc_count += ext4_free_blks_count(sb, gdp);
638                 brelse(bitmap_bh);
639                 bitmap_bh = ext4_read_block_bitmap(sb, i);
640                 if (bitmap_bh == NULL)
641                         continue;
642
643                 x = ext4_count_free(bitmap_bh, sb->s_blocksize);
644                 printk(KERN_DEBUG "group %u: stored = %d, counted = %u\n",
645                         i, ext4_free_blks_count(sb, gdp), x);
646                 bitmap_count += x;
647         }
648         brelse(bitmap_bh);
649         printk(KERN_DEBUG "ext4_count_free_blocks: stored = %llu"
650                 ", computed = %llu, %llu\n", ext4_free_blocks_count(es),
651                desc_count, bitmap_count);
652         return bitmap_count;
653 #else
654         desc_count = 0;
655         for (i = 0; i < ngroups; i++) {
656                 gdp = ext4_get_group_desc(sb, i, NULL);
657                 if (!gdp)
658                         continue;
659                 desc_count += ext4_free_blks_count(sb, gdp);
660         }
661
662         return desc_count;
663 #endif
664 }
665
666 static inline int test_root(ext4_group_t a, int b)
667 {
668         int num = b;
669
670         while (a > num)
671                 num *= b;
672         return num == a;
673 }
674
675 static int ext4_group_sparse(ext4_group_t group)
676 {
677         if (group <= 1)
678                 return 1;
679         if (!(group & 1))
680                 return 0;
681         return (test_root(group, 7) || test_root(group, 5) ||
682                 test_root(group, 3));
683 }
684
685 /**
686  *      ext4_bg_has_super - number of blocks used by the superblock in group
687  *      @sb: superblock for filesystem
688  *      @group: group number to check
689  *
690  *      Return the number of blocks used by the superblock (primary or backup)
691  *      in this group.  Currently this will be only 0 or 1.
692  */
693 int ext4_bg_has_super(struct super_block *sb, ext4_group_t group)
694 {
695         if (EXT4_HAS_RO_COMPAT_FEATURE(sb,
696                                 EXT4_FEATURE_RO_COMPAT_SPARSE_SUPER) &&
697                         !ext4_group_sparse(group))
698                 return 0;
699         return 1;
700 }
701
702 static unsigned long ext4_bg_num_gdb_meta(struct super_block *sb,
703                                         ext4_group_t group)
704 {
705         unsigned long metagroup = group / EXT4_DESC_PER_BLOCK(sb);
706         ext4_group_t first = metagroup * EXT4_DESC_PER_BLOCK(sb);
707         ext4_group_t last = first + EXT4_DESC_PER_BLOCK(sb) - 1;
708
709         if (group == first || group == first + 1 || group == last)
710                 return 1;
711         return 0;
712 }
713
714 static unsigned long ext4_bg_num_gdb_nometa(struct super_block *sb,
715                                         ext4_group_t group)
716 {
717         if (!ext4_bg_has_super(sb, group))
718                 return 0;
719
720         if (EXT4_HAS_INCOMPAT_FEATURE(sb,EXT4_FEATURE_INCOMPAT_META_BG))
721                 return le32_to_cpu(EXT4_SB(sb)->s_es->s_first_meta_bg);
722         else
723                 return EXT4_SB(sb)->s_gdb_count;
724 }
725
726 /**
727  *      ext4_bg_num_gdb - number of blocks used by the group table in group
728  *      @sb: superblock for filesystem
729  *      @group: group number to check
730  *
731  *      Return the number of blocks used by the group descriptor table
732  *      (primary or backup) in this group.  In the future there may be a
733  *      different number of descriptor blocks in each group.
734  */
735 unsigned long ext4_bg_num_gdb(struct super_block *sb, ext4_group_t group)
736 {
737         unsigned long first_meta_bg =
738                         le32_to_cpu(EXT4_SB(sb)->s_es->s_first_meta_bg);
739         unsigned long metagroup = group / EXT4_DESC_PER_BLOCK(sb);
740
741         if (!EXT4_HAS_INCOMPAT_FEATURE(sb,EXT4_FEATURE_INCOMPAT_META_BG) ||
742                         metagroup < first_meta_bg)
743                 return ext4_bg_num_gdb_nometa(sb, group);
744
745         return ext4_bg_num_gdb_meta(sb,group);
746
747 }
748