ext4: fix up a undefined error in ext4_free_blocks in debugging code
[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 into the block/cluster
32  * allocation bitmap, given a block number
33  */
34 void ext4_get_group_no_and_offset(struct super_block *sb, ext4_fsblk_t blocknr,
35                 ext4_group_t *blockgrpp, ext4_grpblk_t *offsetp)
36 {
37         struct ext4_super_block *es = EXT4_SB(sb)->s_es;
38         ext4_grpblk_t offset;
39
40         blocknr = blocknr - le32_to_cpu(es->s_first_data_block);
41         offset = do_div(blocknr, EXT4_BLOCKS_PER_GROUP(sb)) >>
42                 EXT4_SB(sb)->s_cluster_bits;
43         if (offsetp)
44                 *offsetp = offset;
45         if (blockgrpp)
46                 *blockgrpp = blocknr;
47
48 }
49
50 static int ext4_block_in_group(struct super_block *sb, ext4_fsblk_t block,
51                         ext4_group_t block_group)
52 {
53         ext4_group_t actual_group;
54         ext4_get_group_no_and_offset(sb, block, &actual_group, NULL);
55         if (actual_group == block_group)
56                 return 1;
57         return 0;
58 }
59
60 /* Return the number of clusters used for file system metadata; this
61  * represents the overhead needed by the file system.
62  */
63 unsigned ext4_num_overhead_clusters(struct super_block *sb,
64                                     ext4_group_t block_group,
65                                     struct ext4_group_desc *gdp)
66 {
67         unsigned num_clusters;
68         int block_cluster = -1, inode_cluster = -1, itbl_cluster = -1, i, c;
69         ext4_fsblk_t start = ext4_group_first_block_no(sb, block_group);
70         ext4_fsblk_t itbl_blk;
71         struct ext4_sb_info *sbi = EXT4_SB(sb);
72
73         /* This is the number of clusters used by the superblock,
74          * block group descriptors, and reserved block group
75          * descriptor blocks */
76         num_clusters = ext4_num_base_meta_clusters(sb, block_group);
77
78         /*
79          * For the allocation bitmaps and inode table, we first need
80          * to check to see if the block is in the block group.  If it
81          * is, then check to see if the cluster is already accounted
82          * for in the clusters used for the base metadata cluster, or
83          * if we can increment the base metadata cluster to include
84          * that block.  Otherwise, we will have to track the cluster
85          * used for the allocation bitmap or inode table explicitly.
86          * Normally all of these blocks are contiguous, so the special
87          * case handling shouldn't be necessary except for *very*
88          * unusual file system layouts.
89          */
90         if (ext4_block_in_group(sb, ext4_block_bitmap(sb, gdp), block_group)) {
91                 block_cluster = EXT4_B2C(sbi, (start -
92                                                ext4_block_bitmap(sb, gdp)));
93                 if (block_cluster < num_clusters)
94                         block_cluster = -1;
95                 else if (block_cluster == num_clusters) {
96                         num_clusters++;
97                         block_cluster = -1;
98                 }
99         }
100
101         if (ext4_block_in_group(sb, ext4_inode_bitmap(sb, gdp), block_group)) {
102                 inode_cluster = EXT4_B2C(sbi,
103                                          start - ext4_inode_bitmap(sb, gdp));
104                 if (inode_cluster < num_clusters)
105                         inode_cluster = -1;
106                 else if (inode_cluster == num_clusters) {
107                         num_clusters++;
108                         inode_cluster = -1;
109                 }
110         }
111
112         itbl_blk = ext4_inode_table(sb, gdp);
113         for (i = 0; i < sbi->s_itb_per_group; i++) {
114                 if (ext4_block_in_group(sb, itbl_blk + i, block_group)) {
115                         c = EXT4_B2C(sbi, start - itbl_blk + i);
116                         if ((c < num_clusters) || (c == inode_cluster) ||
117                             (c == block_cluster) || (c == itbl_cluster))
118                                 continue;
119                         if (c == num_clusters) {
120                                 num_clusters++;
121                                 continue;
122                         }
123                         num_clusters++;
124                         itbl_cluster = c;
125                 }
126         }
127
128         if (block_cluster != -1)
129                 num_clusters++;
130         if (inode_cluster != -1)
131                 num_clusters++;
132
133         return num_clusters;
134 }
135
136 static unsigned int num_clusters_in_group(struct super_block *sb,
137                                           ext4_group_t block_group)
138 {
139         unsigned int blocks;
140
141         if (block_group == ext4_get_groups_count(sb) - 1) {
142                 /*
143                  * Even though mke2fs always initializes the first and
144                  * last group, just in case some other tool was used,
145                  * we need to make sure we calculate the right free
146                  * blocks.
147                  */
148                 blocks = ext4_blocks_count(EXT4_SB(sb)->s_es) -
149                         ext4_group_first_block_no(sb, block_group);
150         } else
151                 blocks = EXT4_BLOCKS_PER_GROUP(sb);
152         return EXT4_NUM_B2C(EXT4_SB(sb), blocks);
153 }
154
155 /* Initializes an uninitialized block bitmap */
156 void ext4_init_block_bitmap(struct super_block *sb, struct buffer_head *bh,
157                             ext4_group_t block_group,
158                             struct ext4_group_desc *gdp)
159 {
160         unsigned int bit, bit_max;
161         struct ext4_sb_info *sbi = EXT4_SB(sb);
162         ext4_fsblk_t start, tmp;
163         int flex_bg = 0;
164
165         J_ASSERT_BH(bh, buffer_locked(bh));
166
167         /* If checksum is bad mark all blocks used to prevent allocation
168          * essentially implementing a per-group read-only flag. */
169         if (!ext4_group_desc_csum_verify(sbi, block_group, gdp)) {
170                 ext4_error(sb, "Checksum bad for group %u", block_group);
171                 ext4_free_group_clusters_set(sb, gdp, 0);
172                 ext4_free_inodes_set(sb, gdp, 0);
173                 ext4_itable_unused_set(sb, gdp, 0);
174                 memset(bh->b_data, 0xff, sb->s_blocksize);
175                 return;
176         }
177         memset(bh->b_data, 0, sb->s_blocksize);
178
179         bit_max = ext4_num_base_meta_clusters(sb, block_group);
180         for (bit = 0; bit < bit_max; bit++)
181                 ext4_set_bit(bit, bh->b_data);
182
183         start = ext4_group_first_block_no(sb, block_group);
184
185         if (EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_FLEX_BG))
186                 flex_bg = 1;
187
188         /* Set bits for block and inode bitmaps, and inode table */
189         tmp = ext4_block_bitmap(sb, gdp);
190         if (!flex_bg || ext4_block_in_group(sb, tmp, block_group))
191                 ext4_set_bit(EXT4_B2C(sbi, tmp - start), bh->b_data);
192
193         tmp = ext4_inode_bitmap(sb, gdp);
194         if (!flex_bg || ext4_block_in_group(sb, tmp, block_group))
195                 ext4_set_bit(EXT4_B2C(sbi, tmp - start), bh->b_data);
196
197         tmp = ext4_inode_table(sb, gdp);
198         for (; tmp < ext4_inode_table(sb, gdp) +
199                      sbi->s_itb_per_group; tmp++) {
200                 if (!flex_bg || ext4_block_in_group(sb, tmp, block_group))
201                         ext4_set_bit(EXT4_B2C(sbi, tmp - start), bh->b_data);
202         }
203
204         /*
205          * Also if the number of blocks within the group is less than
206          * the blocksize * 8 ( which is the size of bitmap ), set rest
207          * of the block bitmap to 1
208          */
209         ext4_mark_bitmap_end(num_clusters_in_group(sb, block_group),
210                              sb->s_blocksize * 8, bh->b_data);
211 }
212
213 /* Return the number of free blocks in a block group.  It is used when
214  * the block bitmap is uninitialized, so we can't just count the bits
215  * in the bitmap. */
216 unsigned ext4_free_clusters_after_init(struct super_block *sb,
217                                        ext4_group_t block_group,
218                                        struct ext4_group_desc *gdp)
219 {
220         return num_clusters_in_group(sb, block_group) - 
221                 ext4_num_overhead_clusters(sb, block_group, gdp);
222 }
223
224 /*
225  * The free blocks are managed by bitmaps.  A file system contains several
226  * blocks groups.  Each group contains 1 bitmap block for blocks, 1 bitmap
227  * block for inodes, N blocks for the inode table and data blocks.
228  *
229  * The file system contains group descriptors which are located after the
230  * super block.  Each descriptor contains the number of the bitmap block and
231  * the free blocks count in the block.  The descriptors are loaded in memory
232  * when a file system is mounted (see ext4_fill_super).
233  */
234
235 /**
236  * ext4_get_group_desc() -- load group descriptor from disk
237  * @sb:                 super block
238  * @block_group:        given block group
239  * @bh:                 pointer to the buffer head to store the block
240  *                      group descriptor
241  */
242 struct ext4_group_desc * ext4_get_group_desc(struct super_block *sb,
243                                              ext4_group_t block_group,
244                                              struct buffer_head **bh)
245 {
246         unsigned int group_desc;
247         unsigned int offset;
248         ext4_group_t ngroups = ext4_get_groups_count(sb);
249         struct ext4_group_desc *desc;
250         struct ext4_sb_info *sbi = EXT4_SB(sb);
251
252         if (block_group >= ngroups) {
253                 ext4_error(sb, "block_group >= groups_count - block_group = %u,"
254                            " groups_count = %u", block_group, ngroups);
255
256                 return NULL;
257         }
258
259         group_desc = block_group >> EXT4_DESC_PER_BLOCK_BITS(sb);
260         offset = block_group & (EXT4_DESC_PER_BLOCK(sb) - 1);
261         if (!sbi->s_group_desc[group_desc]) {
262                 ext4_error(sb, "Group descriptor not loaded - "
263                            "block_group = %u, group_desc = %u, desc = %u",
264                            block_group, group_desc, offset);
265                 return NULL;
266         }
267
268         desc = (struct ext4_group_desc *)(
269                 (__u8 *)sbi->s_group_desc[group_desc]->b_data +
270                 offset * EXT4_DESC_SIZE(sb));
271         if (bh)
272                 *bh = sbi->s_group_desc[group_desc];
273         return desc;
274 }
275
276 static int ext4_valid_block_bitmap(struct super_block *sb,
277                                         struct ext4_group_desc *desc,
278                                         unsigned int block_group,
279                                         struct buffer_head *bh)
280 {
281         ext4_grpblk_t offset;
282         ext4_grpblk_t next_zero_bit;
283         ext4_fsblk_t bitmap_blk;
284         ext4_fsblk_t group_first_block;
285
286         if (EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_FLEX_BG)) {
287                 /* with FLEX_BG, the inode/block bitmaps and itable
288                  * blocks may not be in the group at all
289                  * so the bitmap validation will be skipped for those groups
290                  * or it has to also read the block group where the bitmaps
291                  * are located to verify they are set.
292                  */
293                 return 1;
294         }
295         group_first_block = ext4_group_first_block_no(sb, block_group);
296
297         /* check whether block bitmap block number is set */
298         bitmap_blk = ext4_block_bitmap(sb, desc);
299         offset = bitmap_blk - group_first_block;
300         if (!ext4_test_bit(offset, bh->b_data))
301                 /* bad block bitmap */
302                 goto err_out;
303
304         /* check whether the inode bitmap block number is set */
305         bitmap_blk = ext4_inode_bitmap(sb, desc);
306         offset = bitmap_blk - group_first_block;
307         if (!ext4_test_bit(offset, bh->b_data))
308                 /* bad block bitmap */
309                 goto err_out;
310
311         /* check whether the inode table block number is set */
312         bitmap_blk = ext4_inode_table(sb, desc);
313         offset = bitmap_blk - group_first_block;
314         next_zero_bit = ext4_find_next_zero_bit(bh->b_data,
315                                 offset + EXT4_SB(sb)->s_itb_per_group,
316                                 offset);
317         if (next_zero_bit >= offset + EXT4_SB(sb)->s_itb_per_group)
318                 /* good bitmap for inode tables */
319                 return 1;
320
321 err_out:
322         ext4_error(sb, "Invalid block bitmap - block_group = %d, block = %llu",
323                         block_group, bitmap_blk);
324         return 0;
325 }
326 /**
327  * ext4_read_block_bitmap()
328  * @sb:                 super block
329  * @block_group:        given block group
330  *
331  * Read the bitmap for a given block_group,and validate the
332  * bits for block/inode/inode tables are set in the bitmaps
333  *
334  * Return buffer_head on success or NULL in case of failure.
335  */
336 struct buffer_head *
337 ext4_read_block_bitmap(struct super_block *sb, ext4_group_t block_group)
338 {
339         struct ext4_group_desc *desc;
340         struct buffer_head *bh = NULL;
341         ext4_fsblk_t bitmap_blk;
342
343         desc = ext4_get_group_desc(sb, block_group, NULL);
344         if (!desc)
345                 return NULL;
346         bitmap_blk = ext4_block_bitmap(sb, desc);
347         bh = sb_getblk(sb, bitmap_blk);
348         if (unlikely(!bh)) {
349                 ext4_error(sb, "Cannot read block bitmap - "
350                             "block_group = %u, block_bitmap = %llu",
351                             block_group, bitmap_blk);
352                 return NULL;
353         }
354
355         if (bitmap_uptodate(bh))
356                 return bh;
357
358         lock_buffer(bh);
359         if (bitmap_uptodate(bh)) {
360                 unlock_buffer(bh);
361                 return bh;
362         }
363         ext4_lock_group(sb, block_group);
364         if (desc->bg_flags & cpu_to_le16(EXT4_BG_BLOCK_UNINIT)) {
365                 ext4_init_block_bitmap(sb, bh, block_group, desc);
366                 set_bitmap_uptodate(bh);
367                 set_buffer_uptodate(bh);
368                 ext4_unlock_group(sb, block_group);
369                 unlock_buffer(bh);
370                 return bh;
371         }
372         ext4_unlock_group(sb, block_group);
373         if (buffer_uptodate(bh)) {
374                 /*
375                  * if not uninit if bh is uptodate,
376                  * bitmap is also uptodate
377                  */
378                 set_bitmap_uptodate(bh);
379                 unlock_buffer(bh);
380                 return bh;
381         }
382         /*
383          * submit the buffer_head for read. We can
384          * safely mark the bitmap as uptodate now.
385          * We do it here so the bitmap uptodate bit
386          * get set with buffer lock held.
387          */
388         trace_ext4_read_block_bitmap_load(sb, block_group);
389         set_bitmap_uptodate(bh);
390         if (bh_submit_read(bh) < 0) {
391                 put_bh(bh);
392                 ext4_error(sb, "Cannot read block bitmap - "
393                             "block_group = %u, block_bitmap = %llu",
394                             block_group, bitmap_blk);
395                 return NULL;
396         }
397         ext4_valid_block_bitmap(sb, desc, block_group, bh);
398         /*
399          * file system mounted not to panic on error,
400          * continue with corrupt bitmap
401          */
402         return bh;
403 }
404
405 /**
406  * ext4_has_free_clusters()
407  * @sbi:        in-core super block structure.
408  * @nclusters:  number of needed blocks
409  * @flags:      flags from ext4_mb_new_blocks()
410  *
411  * Check if filesystem has nclusters free & available for allocation.
412  * On success return 1, return 0 on failure.
413  */
414 static int ext4_has_free_clusters(struct ext4_sb_info *sbi,
415                                   s64 nclusters, unsigned int flags)
416 {
417         s64 free_clusters, dirty_clusters, root_clusters;
418         struct percpu_counter *fcc = &sbi->s_freeclusters_counter;
419         struct percpu_counter *dcc = &sbi->s_dirtyclusters_counter;
420
421         free_clusters  = percpu_counter_read_positive(fcc);
422         dirty_clusters = percpu_counter_read_positive(dcc);
423         root_clusters = EXT4_B2C(sbi, ext4_r_blocks_count(sbi->s_es));
424
425         if (free_clusters - (nclusters + root_clusters + dirty_clusters) <
426                                         EXT4_FREECLUSTERS_WATERMARK) {
427                 free_clusters  = EXT4_C2B(sbi, percpu_counter_sum_positive(fcc));
428                 dirty_clusters = percpu_counter_sum_positive(dcc);
429         }
430         /* Check whether we have space after accounting for current
431          * dirty clusters & root reserved clusters.
432          */
433         if (free_clusters >= ((root_clusters + nclusters) + dirty_clusters))
434                 return 1;
435
436         /* Hm, nope.  Are (enough) root reserved clusters available? */
437         if (sbi->s_resuid == current_fsuid() ||
438             ((sbi->s_resgid != 0) && in_group_p(sbi->s_resgid)) ||
439             capable(CAP_SYS_RESOURCE) ||
440                 (flags & EXT4_MB_USE_ROOT_BLOCKS)) {
441
442                 if (free_clusters >= (nclusters + dirty_clusters))
443                         return 1;
444         }
445
446         return 0;
447 }
448
449 int ext4_claim_free_clusters(struct ext4_sb_info *sbi,
450                              s64 nclusters, unsigned int flags)
451 {
452         if (ext4_has_free_clusters(sbi, nclusters, flags)) {
453                 percpu_counter_add(&sbi->s_dirtyclusters_counter, nclusters);
454                 return 0;
455         } else
456                 return -ENOSPC;
457 }
458
459 /**
460  * ext4_should_retry_alloc()
461  * @sb:                 super block
462  * @retries             number of attemps has been made
463  *
464  * ext4_should_retry_alloc() is called when ENOSPC is returned, and if
465  * it is profitable to retry the operation, this function will wait
466  * for the current or committing transaction to complete, and then
467  * return TRUE.
468  *
469  * if the total number of retries exceed three times, return FALSE.
470  */
471 int ext4_should_retry_alloc(struct super_block *sb, int *retries)
472 {
473         if (!ext4_has_free_clusters(EXT4_SB(sb), 1, 0) ||
474             (*retries)++ > 3 ||
475             !EXT4_SB(sb)->s_journal)
476                 return 0;
477
478         jbd_debug(1, "%s: retrying operation after ENOSPC\n", sb->s_id);
479
480         return jbd2_journal_force_commit_nested(EXT4_SB(sb)->s_journal);
481 }
482
483 /*
484  * ext4_new_meta_blocks() -- allocate block for meta data (indexing) blocks
485  *
486  * @handle:             handle to this transaction
487  * @inode:              file inode
488  * @goal:               given target block(filesystem wide)
489  * @count:              pointer to total number of clusters needed
490  * @errp:               error code
491  *
492  * Return 1st allocated block number on success, *count stores total account
493  * error stores in errp pointer
494  */
495 ext4_fsblk_t ext4_new_meta_blocks(handle_t *handle, struct inode *inode,
496                                   ext4_fsblk_t goal, unsigned int flags,
497                                   unsigned long *count, int *errp)
498 {
499         struct ext4_allocation_request ar;
500         ext4_fsblk_t ret;
501
502         memset(&ar, 0, sizeof(ar));
503         /* Fill with neighbour allocated blocks */
504         ar.inode = inode;
505         ar.goal = goal;
506         ar.len = count ? *count : 1;
507         ar.flags = flags;
508
509         ret = ext4_mb_new_blocks(handle, &ar, errp);
510         if (count)
511                 *count = ar.len;
512         /*
513          * Account for the allocated meta blocks.  We will never
514          * fail EDQUOT for metdata, but we do account for it.
515          */
516         if (!(*errp) &&
517             ext4_test_inode_state(inode, EXT4_STATE_DELALLOC_RESERVED)) {
518                 spin_lock(&EXT4_I(inode)->i_block_reservation_lock);
519                 EXT4_I(inode)->i_allocated_meta_blocks += ar.len;
520                 spin_unlock(&EXT4_I(inode)->i_block_reservation_lock);
521                 dquot_alloc_block_nofail(inode,
522                                 EXT4_C2B(EXT4_SB(inode->i_sb), ar.len));
523         }
524         return ret;
525 }
526
527 /**
528  * ext4_count_free_clusters() -- count filesystem free clusters
529  * @sb:         superblock
530  *
531  * Adds up the number of free clusters from each block group.
532  */
533 ext4_fsblk_t ext4_count_free_clusters(struct super_block *sb)
534 {
535         ext4_fsblk_t desc_count;
536         struct ext4_group_desc *gdp;
537         ext4_group_t i;
538         ext4_group_t ngroups = ext4_get_groups_count(sb);
539 #ifdef EXT4FS_DEBUG
540         struct ext4_super_block *es;
541         ext4_fsblk_t bitmap_count;
542         unsigned int x;
543         struct buffer_head *bitmap_bh = NULL;
544
545         es = EXT4_SB(sb)->s_es;
546         desc_count = 0;
547         bitmap_count = 0;
548         gdp = NULL;
549
550         for (i = 0; i < ngroups; i++) {
551                 gdp = ext4_get_group_desc(sb, i, NULL);
552                 if (!gdp)
553                         continue;
554                 desc_count += ext4_free_group_clusters(sb, gdp);
555                 brelse(bitmap_bh);
556                 bitmap_bh = ext4_read_block_bitmap(sb, i);
557                 if (bitmap_bh == NULL)
558                         continue;
559
560                 x = ext4_count_free(bitmap_bh, sb->s_blocksize);
561                 printk(KERN_DEBUG "group %u: stored = %d, counted = %u\n",
562                         i, ext4_free_group_clusters(sb, gdp), x);
563                 bitmap_count += x;
564         }
565         brelse(bitmap_bh);
566         printk(KERN_DEBUG "ext4_count_free_clusters: stored = %llu"
567                ", computed = %llu, %llu\n",
568                EXT4_B2C(EXT4_SB(sb), ext4_free_blocks_count(es)),
569                desc_count, bitmap_count);
570         return bitmap_count;
571 #else
572         desc_count = 0;
573         for (i = 0; i < ngroups; i++) {
574                 gdp = ext4_get_group_desc(sb, i, NULL);
575                 if (!gdp)
576                         continue;
577                 desc_count += ext4_free_group_clusters(sb, gdp);
578         }
579
580         return desc_count;
581 #endif
582 }
583
584 static inline int test_root(ext4_group_t a, int b)
585 {
586         int num = b;
587
588         while (a > num)
589                 num *= b;
590         return num == a;
591 }
592
593 static int ext4_group_sparse(ext4_group_t group)
594 {
595         if (group <= 1)
596                 return 1;
597         if (!(group & 1))
598                 return 0;
599         return (test_root(group, 7) || test_root(group, 5) ||
600                 test_root(group, 3));
601 }
602
603 /**
604  *      ext4_bg_has_super - number of blocks used by the superblock in group
605  *      @sb: superblock for filesystem
606  *      @group: group number to check
607  *
608  *      Return the number of blocks used by the superblock (primary or backup)
609  *      in this group.  Currently this will be only 0 or 1.
610  */
611 int ext4_bg_has_super(struct super_block *sb, ext4_group_t group)
612 {
613         if (EXT4_HAS_RO_COMPAT_FEATURE(sb,
614                                 EXT4_FEATURE_RO_COMPAT_SPARSE_SUPER) &&
615                         !ext4_group_sparse(group))
616                 return 0;
617         return 1;
618 }
619
620 static unsigned long ext4_bg_num_gdb_meta(struct super_block *sb,
621                                         ext4_group_t group)
622 {
623         unsigned long metagroup = group / EXT4_DESC_PER_BLOCK(sb);
624         ext4_group_t first = metagroup * EXT4_DESC_PER_BLOCK(sb);
625         ext4_group_t last = first + EXT4_DESC_PER_BLOCK(sb) - 1;
626
627         if (group == first || group == first + 1 || group == last)
628                 return 1;
629         return 0;
630 }
631
632 static unsigned long ext4_bg_num_gdb_nometa(struct super_block *sb,
633                                         ext4_group_t group)
634 {
635         if (!ext4_bg_has_super(sb, group))
636                 return 0;
637
638         if (EXT4_HAS_INCOMPAT_FEATURE(sb,EXT4_FEATURE_INCOMPAT_META_BG))
639                 return le32_to_cpu(EXT4_SB(sb)->s_es->s_first_meta_bg);
640         else
641                 return EXT4_SB(sb)->s_gdb_count;
642 }
643
644 /**
645  *      ext4_bg_num_gdb - number of blocks used by the group table in group
646  *      @sb: superblock for filesystem
647  *      @group: group number to check
648  *
649  *      Return the number of blocks used by the group descriptor table
650  *      (primary or backup) in this group.  In the future there may be a
651  *      different number of descriptor blocks in each group.
652  */
653 unsigned long ext4_bg_num_gdb(struct super_block *sb, ext4_group_t group)
654 {
655         unsigned long first_meta_bg =
656                         le32_to_cpu(EXT4_SB(sb)->s_es->s_first_meta_bg);
657         unsigned long metagroup = group / EXT4_DESC_PER_BLOCK(sb);
658
659         if (!EXT4_HAS_INCOMPAT_FEATURE(sb,EXT4_FEATURE_INCOMPAT_META_BG) ||
660                         metagroup < first_meta_bg)
661                 return ext4_bg_num_gdb_nometa(sb, group);
662
663         return ext4_bg_num_gdb_meta(sb,group);
664
665 }
666
667 /*
668  * This function returns the number of file system metadata clusters at
669  * the beginning of a block group, including the reserved gdt blocks.
670  */
671 unsigned ext4_num_base_meta_clusters(struct super_block *sb,
672                                      ext4_group_t block_group)
673 {
674         struct ext4_sb_info *sbi = EXT4_SB(sb);
675         unsigned num;
676
677         /* Check for superblock and gdt backups in this group */
678         num = ext4_bg_has_super(sb, block_group);
679
680         if (!EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_META_BG) ||
681             block_group < le32_to_cpu(sbi->s_es->s_first_meta_bg) *
682                           sbi->s_desc_per_block) {
683                 if (num) {
684                         num += ext4_bg_num_gdb(sb, block_group);
685                         num += le16_to_cpu(sbi->s_es->s_reserved_gdt_blocks);
686                 }
687         } else { /* For META_BG_BLOCK_GROUPS */
688                 num += ext4_bg_num_gdb(sb, block_group);
689         }
690         return EXT4_NUM_B2C(sbi, num);
691 }
692 /**
693  *      ext4_inode_to_goal_block - return a hint for block allocation
694  *      @inode: inode for block allocation
695  *
696  *      Return the ideal location to start allocating blocks for a
697  *      newly created inode.
698  */
699 ext4_fsblk_t ext4_inode_to_goal_block(struct inode *inode)
700 {
701         struct ext4_inode_info *ei = EXT4_I(inode);
702         ext4_group_t block_group;
703         ext4_grpblk_t colour;
704         int flex_size = ext4_flex_bg_size(EXT4_SB(inode->i_sb));
705         ext4_fsblk_t bg_start;
706         ext4_fsblk_t last_block;
707
708         block_group = ei->i_block_group;
709         if (flex_size >= EXT4_FLEX_SIZE_DIR_ALLOC_SCHEME) {
710                 /*
711                  * If there are at least EXT4_FLEX_SIZE_DIR_ALLOC_SCHEME
712                  * block groups per flexgroup, reserve the first block
713                  * group for directories and special files.  Regular
714                  * files will start at the second block group.  This
715                  * tends to speed up directory access and improves
716                  * fsck times.
717                  */
718                 block_group &= ~(flex_size-1);
719                 if (S_ISREG(inode->i_mode))
720                         block_group++;
721         }
722         bg_start = ext4_group_first_block_no(inode->i_sb, block_group);
723         last_block = ext4_blocks_count(EXT4_SB(inode->i_sb)->s_es) - 1;
724
725         /*
726          * If we are doing delayed allocation, we don't need take
727          * colour into account.
728          */
729         if (test_opt(inode->i_sb, DELALLOC))
730                 return bg_start;
731
732         if (bg_start + EXT4_BLOCKS_PER_GROUP(inode->i_sb) <= last_block)
733                 colour = (current->pid % 16) *
734                         (EXT4_BLOCKS_PER_GROUP(inode->i_sb) / 16);
735         else
736                 colour = (current->pid % 16) * ((last_block - bg_start) / 16);
737         return bg_start + colour;
738 }
739