Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi...
[cascardo/linux.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/quotaops.h>
18 #include <linux/buffer_head.h>
19 #include "ext4.h"
20 #include "ext4_jbd2.h"
21 #include "mballoc.h"
22
23 #include <trace/events/ext4.h>
24
25 static unsigned ext4_num_base_meta_clusters(struct super_block *sb,
26                                             ext4_group_t block_group);
27 /*
28  * balloc.c contains the blocks allocation and deallocation routines
29  */
30
31 /*
32  * Calculate block group number for a given block number
33  */
34 ext4_group_t ext4_get_group_number(struct super_block *sb,
35                                    ext4_fsblk_t block)
36 {
37         ext4_group_t group;
38
39         if (test_opt2(sb, STD_GROUP_SIZE))
40                 group = (block -
41                          le32_to_cpu(EXT4_SB(sb)->s_es->s_first_data_block)) >>
42                         (EXT4_BLOCK_SIZE_BITS(sb) + EXT4_CLUSTER_BITS(sb) + 3);
43         else
44                 ext4_get_group_no_and_offset(sb, block, &group, NULL);
45         return group;
46 }
47
48 /*
49  * Calculate the block group number and offset into the block/cluster
50  * allocation bitmap, given a block number
51  */
52 void ext4_get_group_no_and_offset(struct super_block *sb, ext4_fsblk_t blocknr,
53                 ext4_group_t *blockgrpp, ext4_grpblk_t *offsetp)
54 {
55         struct ext4_super_block *es = EXT4_SB(sb)->s_es;
56         ext4_grpblk_t offset;
57
58         blocknr = blocknr - le32_to_cpu(es->s_first_data_block);
59         offset = do_div(blocknr, EXT4_BLOCKS_PER_GROUP(sb)) >>
60                 EXT4_SB(sb)->s_cluster_bits;
61         if (offsetp)
62                 *offsetp = offset;
63         if (blockgrpp)
64                 *blockgrpp = blocknr;
65
66 }
67
68 /*
69  * Check whether the 'block' lives within the 'block_group'. Returns 1 if so
70  * and 0 otherwise.
71  */
72 static inline int ext4_block_in_group(struct super_block *sb,
73                                       ext4_fsblk_t block,
74                                       ext4_group_t block_group)
75 {
76         ext4_group_t actual_group;
77
78         actual_group = ext4_get_group_number(sb, block);
79         return (actual_group == block_group) ? 1 : 0;
80 }
81
82 /* Return the number of clusters used for file system metadata; this
83  * represents the overhead needed by the file system.
84  */
85 static unsigned ext4_num_overhead_clusters(struct super_block *sb,
86                                            ext4_group_t block_group,
87                                            struct ext4_group_desc *gdp)
88 {
89         unsigned num_clusters;
90         int block_cluster = -1, inode_cluster = -1, itbl_cluster = -1, i, c;
91         ext4_fsblk_t start = ext4_group_first_block_no(sb, block_group);
92         ext4_fsblk_t itbl_blk;
93         struct ext4_sb_info *sbi = EXT4_SB(sb);
94
95         /* This is the number of clusters used by the superblock,
96          * block group descriptors, and reserved block group
97          * descriptor blocks */
98         num_clusters = ext4_num_base_meta_clusters(sb, block_group);
99
100         /*
101          * For the allocation bitmaps and inode table, we first need
102          * to check to see if the block is in the block group.  If it
103          * is, then check to see if the cluster is already accounted
104          * for in the clusters used for the base metadata cluster, or
105          * if we can increment the base metadata cluster to include
106          * that block.  Otherwise, we will have to track the cluster
107          * used for the allocation bitmap or inode table explicitly.
108          * Normally all of these blocks are contiguous, so the special
109          * case handling shouldn't be necessary except for *very*
110          * unusual file system layouts.
111          */
112         if (ext4_block_in_group(sb, ext4_block_bitmap(sb, gdp), block_group)) {
113                 block_cluster = EXT4_B2C(sbi,
114                                          ext4_block_bitmap(sb, gdp) - start);
115                 if (block_cluster < num_clusters)
116                         block_cluster = -1;
117                 else if (block_cluster == num_clusters) {
118                         num_clusters++;
119                         block_cluster = -1;
120                 }
121         }
122
123         if (ext4_block_in_group(sb, ext4_inode_bitmap(sb, gdp), block_group)) {
124                 inode_cluster = EXT4_B2C(sbi,
125                                          ext4_inode_bitmap(sb, gdp) - start);
126                 if (inode_cluster < num_clusters)
127                         inode_cluster = -1;
128                 else if (inode_cluster == num_clusters) {
129                         num_clusters++;
130                         inode_cluster = -1;
131                 }
132         }
133
134         itbl_blk = ext4_inode_table(sb, gdp);
135         for (i = 0; i < sbi->s_itb_per_group; i++) {
136                 if (ext4_block_in_group(sb, itbl_blk + i, block_group)) {
137                         c = EXT4_B2C(sbi, itbl_blk + i - start);
138                         if ((c < num_clusters) || (c == inode_cluster) ||
139                             (c == block_cluster) || (c == itbl_cluster))
140                                 continue;
141                         if (c == num_clusters) {
142                                 num_clusters++;
143                                 continue;
144                         }
145                         num_clusters++;
146                         itbl_cluster = c;
147                 }
148         }
149
150         if (block_cluster != -1)
151                 num_clusters++;
152         if (inode_cluster != -1)
153                 num_clusters++;
154
155         return num_clusters;
156 }
157
158 static unsigned int num_clusters_in_group(struct super_block *sb,
159                                           ext4_group_t block_group)
160 {
161         unsigned int blocks;
162
163         if (block_group == ext4_get_groups_count(sb) - 1) {
164                 /*
165                  * Even though mke2fs always initializes the first and
166                  * last group, just in case some other tool was used,
167                  * we need to make sure we calculate the right free
168                  * blocks.
169                  */
170                 blocks = ext4_blocks_count(EXT4_SB(sb)->s_es) -
171                         ext4_group_first_block_no(sb, block_group);
172         } else
173                 blocks = EXT4_BLOCKS_PER_GROUP(sb);
174         return EXT4_NUM_B2C(EXT4_SB(sb), blocks);
175 }
176
177 /* Initializes an uninitialized block bitmap */
178 static int ext4_init_block_bitmap(struct super_block *sb,
179                                    struct buffer_head *bh,
180                                    ext4_group_t block_group,
181                                    struct ext4_group_desc *gdp)
182 {
183         unsigned int bit, bit_max;
184         struct ext4_sb_info *sbi = EXT4_SB(sb);
185         ext4_fsblk_t start, tmp;
186         int flex_bg = 0;
187         struct ext4_group_info *grp;
188
189         J_ASSERT_BH(bh, buffer_locked(bh));
190
191         /* If checksum is bad mark all blocks used to prevent allocation
192          * essentially implementing a per-group read-only flag. */
193         if (!ext4_group_desc_csum_verify(sb, block_group, gdp)) {
194                 ext4_error(sb, "Checksum bad for group %u", block_group);
195                 grp = ext4_get_group_info(sb, block_group);
196                 if (!EXT4_MB_GRP_BBITMAP_CORRUPT(grp))
197                         percpu_counter_sub(&sbi->s_freeclusters_counter,
198                                            grp->bb_free);
199                 set_bit(EXT4_GROUP_INFO_BBITMAP_CORRUPT_BIT, &grp->bb_state);
200                 if (!EXT4_MB_GRP_IBITMAP_CORRUPT(grp)) {
201                         int count;
202                         count = ext4_free_inodes_count(sb, gdp);
203                         percpu_counter_sub(&sbi->s_freeinodes_counter,
204                                            count);
205                 }
206                 set_bit(EXT4_GROUP_INFO_IBITMAP_CORRUPT_BIT, &grp->bb_state);
207                 return -EFSBADCRC;
208         }
209         memset(bh->b_data, 0, sb->s_blocksize);
210
211         bit_max = ext4_num_base_meta_clusters(sb, block_group);
212         for (bit = 0; bit < bit_max; bit++)
213                 ext4_set_bit(bit, bh->b_data);
214
215         start = ext4_group_first_block_no(sb, block_group);
216
217         if (ext4_has_feature_flex_bg(sb))
218                 flex_bg = 1;
219
220         /* Set bits for block and inode bitmaps, and inode table */
221         tmp = ext4_block_bitmap(sb, gdp);
222         if (!flex_bg || ext4_block_in_group(sb, tmp, block_group))
223                 ext4_set_bit(EXT4_B2C(sbi, tmp - start), bh->b_data);
224
225         tmp = ext4_inode_bitmap(sb, gdp);
226         if (!flex_bg || ext4_block_in_group(sb, tmp, block_group))
227                 ext4_set_bit(EXT4_B2C(sbi, tmp - start), bh->b_data);
228
229         tmp = ext4_inode_table(sb, gdp);
230         for (; tmp < ext4_inode_table(sb, gdp) +
231                      sbi->s_itb_per_group; tmp++) {
232                 if (!flex_bg || ext4_block_in_group(sb, tmp, block_group))
233                         ext4_set_bit(EXT4_B2C(sbi, tmp - start), bh->b_data);
234         }
235
236         /*
237          * Also if the number of blocks within the group is less than
238          * the blocksize * 8 ( which is the size of bitmap ), set rest
239          * of the block bitmap to 1
240          */
241         ext4_mark_bitmap_end(num_clusters_in_group(sb, block_group),
242                              sb->s_blocksize * 8, bh->b_data);
243         ext4_block_bitmap_csum_set(sb, block_group, gdp, bh);
244         ext4_group_desc_csum_set(sb, block_group, gdp);
245         return 0;
246 }
247
248 /* Return the number of free blocks in a block group.  It is used when
249  * the block bitmap is uninitialized, so we can't just count the bits
250  * in the bitmap. */
251 unsigned ext4_free_clusters_after_init(struct super_block *sb,
252                                        ext4_group_t block_group,
253                                        struct ext4_group_desc *gdp)
254 {
255         return num_clusters_in_group(sb, block_group) - 
256                 ext4_num_overhead_clusters(sb, block_group, gdp);
257 }
258
259 /*
260  * The free blocks are managed by bitmaps.  A file system contains several
261  * blocks groups.  Each group contains 1 bitmap block for blocks, 1 bitmap
262  * block for inodes, N blocks for the inode table and data blocks.
263  *
264  * The file system contains group descriptors which are located after the
265  * super block.  Each descriptor contains the number of the bitmap block and
266  * the free blocks count in the block.  The descriptors are loaded in memory
267  * when a file system is mounted (see ext4_fill_super).
268  */
269
270 /**
271  * ext4_get_group_desc() -- load group descriptor from disk
272  * @sb:                 super block
273  * @block_group:        given block group
274  * @bh:                 pointer to the buffer head to store the block
275  *                      group descriptor
276  */
277 struct ext4_group_desc * ext4_get_group_desc(struct super_block *sb,
278                                              ext4_group_t block_group,
279                                              struct buffer_head **bh)
280 {
281         unsigned int group_desc;
282         unsigned int offset;
283         ext4_group_t ngroups = ext4_get_groups_count(sb);
284         struct ext4_group_desc *desc;
285         struct ext4_sb_info *sbi = EXT4_SB(sb);
286
287         if (block_group >= ngroups) {
288                 ext4_error(sb, "block_group >= groups_count - block_group = %u,"
289                            " groups_count = %u", block_group, ngroups);
290
291                 return NULL;
292         }
293
294         group_desc = block_group >> EXT4_DESC_PER_BLOCK_BITS(sb);
295         offset = block_group & (EXT4_DESC_PER_BLOCK(sb) - 1);
296         if (!sbi->s_group_desc[group_desc]) {
297                 ext4_error(sb, "Group descriptor not loaded - "
298                            "block_group = %u, group_desc = %u, desc = %u",
299                            block_group, group_desc, offset);
300                 return NULL;
301         }
302
303         desc = (struct ext4_group_desc *)(
304                 (__u8 *)sbi->s_group_desc[group_desc]->b_data +
305                 offset * EXT4_DESC_SIZE(sb));
306         if (bh)
307                 *bh = sbi->s_group_desc[group_desc];
308         return desc;
309 }
310
311 /*
312  * Return the block number which was discovered to be invalid, or 0 if
313  * the block bitmap is valid.
314  */
315 static ext4_fsblk_t ext4_valid_block_bitmap(struct super_block *sb,
316                                             struct ext4_group_desc *desc,
317                                             ext4_group_t block_group,
318                                             struct buffer_head *bh)
319 {
320         struct ext4_sb_info *sbi = EXT4_SB(sb);
321         ext4_grpblk_t offset;
322         ext4_grpblk_t next_zero_bit;
323         ext4_fsblk_t blk;
324         ext4_fsblk_t group_first_block;
325
326         if (ext4_has_feature_flex_bg(sb)) {
327                 /* with FLEX_BG, the inode/block bitmaps and itable
328                  * blocks may not be in the group at all
329                  * so the bitmap validation will be skipped for those groups
330                  * or it has to also read the block group where the bitmaps
331                  * are located to verify they are set.
332                  */
333                 return 0;
334         }
335         group_first_block = ext4_group_first_block_no(sb, block_group);
336
337         /* check whether block bitmap block number is set */
338         blk = ext4_block_bitmap(sb, desc);
339         offset = blk - group_first_block;
340         if (!ext4_test_bit(EXT4_B2C(sbi, offset), bh->b_data))
341                 /* bad block bitmap */
342                 return blk;
343
344         /* check whether the inode bitmap block number is set */
345         blk = ext4_inode_bitmap(sb, desc);
346         offset = blk - group_first_block;
347         if (!ext4_test_bit(EXT4_B2C(sbi, offset), bh->b_data))
348                 /* bad block bitmap */
349                 return blk;
350
351         /* check whether the inode table block number is set */
352         blk = ext4_inode_table(sb, desc);
353         offset = blk - group_first_block;
354         next_zero_bit = ext4_find_next_zero_bit(bh->b_data,
355                         EXT4_B2C(sbi, offset + EXT4_SB(sb)->s_itb_per_group),
356                         EXT4_B2C(sbi, offset));
357         if (next_zero_bit <
358             EXT4_B2C(sbi, offset + EXT4_SB(sb)->s_itb_per_group))
359                 /* bad bitmap for inode tables */
360                 return blk;
361         return 0;
362 }
363
364 static int ext4_validate_block_bitmap(struct super_block *sb,
365                                       struct ext4_group_desc *desc,
366                                       ext4_group_t block_group,
367                                       struct buffer_head *bh)
368 {
369         ext4_fsblk_t    blk;
370         struct ext4_group_info *grp = ext4_get_group_info(sb, block_group);
371         struct ext4_sb_info *sbi = EXT4_SB(sb);
372
373         if (buffer_verified(bh))
374                 return 0;
375         if (EXT4_MB_GRP_BBITMAP_CORRUPT(grp))
376                 return -EFSCORRUPTED;
377
378         ext4_lock_group(sb, block_group);
379         if (unlikely(!ext4_block_bitmap_csum_verify(sb, block_group,
380                         desc, bh))) {
381                 ext4_unlock_group(sb, block_group);
382                 ext4_error(sb, "bg %u: bad block bitmap checksum", block_group);
383                 if (!EXT4_MB_GRP_BBITMAP_CORRUPT(grp))
384                         percpu_counter_sub(&sbi->s_freeclusters_counter,
385                                            grp->bb_free);
386                 set_bit(EXT4_GROUP_INFO_BBITMAP_CORRUPT_BIT, &grp->bb_state);
387                 return -EFSBADCRC;
388         }
389         blk = ext4_valid_block_bitmap(sb, desc, block_group, bh);
390         if (unlikely(blk != 0)) {
391                 ext4_unlock_group(sb, block_group);
392                 ext4_error(sb, "bg %u: block %llu: invalid block bitmap",
393                            block_group, blk);
394                 if (!EXT4_MB_GRP_BBITMAP_CORRUPT(grp))
395                         percpu_counter_sub(&sbi->s_freeclusters_counter,
396                                            grp->bb_free);
397                 set_bit(EXT4_GROUP_INFO_BBITMAP_CORRUPT_BIT, &grp->bb_state);
398                 return -EFSCORRUPTED;
399         }
400         set_buffer_verified(bh);
401         ext4_unlock_group(sb, block_group);
402         return 0;
403 }
404
405 /**
406  * ext4_read_block_bitmap_nowait()
407  * @sb:                 super block
408  * @block_group:        given block group
409  *
410  * Read the bitmap for a given block_group,and validate the
411  * bits for block/inode/inode tables are set in the bitmaps
412  *
413  * Return buffer_head on success or NULL in case of failure.
414  */
415 struct buffer_head *
416 ext4_read_block_bitmap_nowait(struct super_block *sb, ext4_group_t block_group)
417 {
418         struct ext4_group_desc *desc;
419         struct buffer_head *bh;
420         ext4_fsblk_t bitmap_blk;
421         int err;
422
423         desc = ext4_get_group_desc(sb, block_group, NULL);
424         if (!desc)
425                 return ERR_PTR(-EFSCORRUPTED);
426         bitmap_blk = ext4_block_bitmap(sb, desc);
427         bh = sb_getblk(sb, bitmap_blk);
428         if (unlikely(!bh)) {
429                 ext4_error(sb, "Cannot get buffer for block bitmap - "
430                            "block_group = %u, block_bitmap = %llu",
431                            block_group, bitmap_blk);
432                 return ERR_PTR(-ENOMEM);
433         }
434
435         if (bitmap_uptodate(bh))
436                 goto verify;
437
438         lock_buffer(bh);
439         if (bitmap_uptodate(bh)) {
440                 unlock_buffer(bh);
441                 goto verify;
442         }
443         ext4_lock_group(sb, block_group);
444         if (desc->bg_flags & cpu_to_le16(EXT4_BG_BLOCK_UNINIT)) {
445
446                 err = ext4_init_block_bitmap(sb, bh, block_group, desc);
447                 set_bitmap_uptodate(bh);
448                 set_buffer_uptodate(bh);
449                 ext4_unlock_group(sb, block_group);
450                 unlock_buffer(bh);
451                 if (err)
452                         goto out;
453                 goto verify;
454         }
455         ext4_unlock_group(sb, block_group);
456         if (buffer_uptodate(bh)) {
457                 /*
458                  * if not uninit if bh is uptodate,
459                  * bitmap is also uptodate
460                  */
461                 set_bitmap_uptodate(bh);
462                 unlock_buffer(bh);
463                 goto verify;
464         }
465         /*
466          * submit the buffer_head for reading
467          */
468         set_buffer_new(bh);
469         trace_ext4_read_block_bitmap_load(sb, block_group);
470         bh->b_end_io = ext4_end_bitmap_read;
471         get_bh(bh);
472         submit_bh(READ | REQ_META | REQ_PRIO, bh);
473         return bh;
474 verify:
475         err = ext4_validate_block_bitmap(sb, desc, block_group, bh);
476         if (err)
477                 goto out;
478         return bh;
479 out:
480         put_bh(bh);
481         return ERR_PTR(err);
482 }
483
484 /* Returns 0 on success, 1 on error */
485 int ext4_wait_block_bitmap(struct super_block *sb, ext4_group_t block_group,
486                            struct buffer_head *bh)
487 {
488         struct ext4_group_desc *desc;
489
490         if (!buffer_new(bh))
491                 return 0;
492         desc = ext4_get_group_desc(sb, block_group, NULL);
493         if (!desc)
494                 return -EFSCORRUPTED;
495         wait_on_buffer(bh);
496         if (!buffer_uptodate(bh)) {
497                 ext4_error(sb, "Cannot read block bitmap - "
498                            "block_group = %u, block_bitmap = %llu",
499                            block_group, (unsigned long long) bh->b_blocknr);
500                 return -EIO;
501         }
502         clear_buffer_new(bh);
503         /* Panic or remount fs read-only if block bitmap is invalid */
504         return ext4_validate_block_bitmap(sb, desc, block_group, bh);
505 }
506
507 struct buffer_head *
508 ext4_read_block_bitmap(struct super_block *sb, ext4_group_t block_group)
509 {
510         struct buffer_head *bh;
511         int err;
512
513         bh = ext4_read_block_bitmap_nowait(sb, block_group);
514         if (IS_ERR(bh))
515                 return bh;
516         err = ext4_wait_block_bitmap(sb, block_group, bh);
517         if (err) {
518                 put_bh(bh);
519                 return ERR_PTR(err);
520         }
521         return bh;
522 }
523
524 /**
525  * ext4_has_free_clusters()
526  * @sbi:        in-core super block structure.
527  * @nclusters:  number of needed blocks
528  * @flags:      flags from ext4_mb_new_blocks()
529  *
530  * Check if filesystem has nclusters free & available for allocation.
531  * On success return 1, return 0 on failure.
532  */
533 static int ext4_has_free_clusters(struct ext4_sb_info *sbi,
534                                   s64 nclusters, unsigned int flags)
535 {
536         s64 free_clusters, dirty_clusters, rsv, resv_clusters;
537         struct percpu_counter *fcc = &sbi->s_freeclusters_counter;
538         struct percpu_counter *dcc = &sbi->s_dirtyclusters_counter;
539
540         free_clusters  = percpu_counter_read_positive(fcc);
541         dirty_clusters = percpu_counter_read_positive(dcc);
542         resv_clusters = atomic64_read(&sbi->s_resv_clusters);
543
544         /*
545          * r_blocks_count should always be multiple of the cluster ratio so
546          * we are safe to do a plane bit shift only.
547          */
548         rsv = (ext4_r_blocks_count(sbi->s_es) >> sbi->s_cluster_bits) +
549               resv_clusters;
550
551         if (free_clusters - (nclusters + rsv + dirty_clusters) <
552                                         EXT4_FREECLUSTERS_WATERMARK) {
553                 free_clusters  = percpu_counter_sum_positive(fcc);
554                 dirty_clusters = percpu_counter_sum_positive(dcc);
555         }
556         /* Check whether we have space after accounting for current
557          * dirty clusters & root reserved clusters.
558          */
559         if (free_clusters >= (rsv + nclusters + dirty_clusters))
560                 return 1;
561
562         /* Hm, nope.  Are (enough) root reserved clusters available? */
563         if (uid_eq(sbi->s_resuid, current_fsuid()) ||
564             (!gid_eq(sbi->s_resgid, GLOBAL_ROOT_GID) && in_group_p(sbi->s_resgid)) ||
565             capable(CAP_SYS_RESOURCE) ||
566             (flags & EXT4_MB_USE_ROOT_BLOCKS)) {
567
568                 if (free_clusters >= (nclusters + dirty_clusters +
569                                       resv_clusters))
570                         return 1;
571         }
572         /* No free blocks. Let's see if we can dip into reserved pool */
573         if (flags & EXT4_MB_USE_RESERVED) {
574                 if (free_clusters >= (nclusters + dirty_clusters))
575                         return 1;
576         }
577
578         return 0;
579 }
580
581 int ext4_claim_free_clusters(struct ext4_sb_info *sbi,
582                              s64 nclusters, unsigned int flags)
583 {
584         if (ext4_has_free_clusters(sbi, nclusters, flags)) {
585                 percpu_counter_add(&sbi->s_dirtyclusters_counter, nclusters);
586                 return 0;
587         } else
588                 return -ENOSPC;
589 }
590
591 /**
592  * ext4_should_retry_alloc()
593  * @sb:                 super block
594  * @retries             number of attemps has been made
595  *
596  * ext4_should_retry_alloc() is called when ENOSPC is returned, and if
597  * it is profitable to retry the operation, this function will wait
598  * for the current or committing transaction to complete, and then
599  * return TRUE.
600  *
601  * if the total number of retries exceed three times, return FALSE.
602  */
603 int ext4_should_retry_alloc(struct super_block *sb, int *retries)
604 {
605         if (!ext4_has_free_clusters(EXT4_SB(sb), 1, 0) ||
606             (*retries)++ > 3 ||
607             !EXT4_SB(sb)->s_journal)
608                 return 0;
609
610         jbd_debug(1, "%s: retrying operation after ENOSPC\n", sb->s_id);
611
612         return jbd2_journal_force_commit_nested(EXT4_SB(sb)->s_journal);
613 }
614
615 /*
616  * ext4_new_meta_blocks() -- allocate block for meta data (indexing) blocks
617  *
618  * @handle:             handle to this transaction
619  * @inode:              file inode
620  * @goal:               given target block(filesystem wide)
621  * @count:              pointer to total number of clusters needed
622  * @errp:               error code
623  *
624  * Return 1st allocated block number on success, *count stores total account
625  * error stores in errp pointer
626  */
627 ext4_fsblk_t ext4_new_meta_blocks(handle_t *handle, struct inode *inode,
628                                   ext4_fsblk_t goal, unsigned int flags,
629                                   unsigned long *count, int *errp)
630 {
631         struct ext4_allocation_request ar;
632         ext4_fsblk_t ret;
633
634         memset(&ar, 0, sizeof(ar));
635         /* Fill with neighbour allocated blocks */
636         ar.inode = inode;
637         ar.goal = goal;
638         ar.len = count ? *count : 1;
639         ar.flags = flags;
640
641         ret = ext4_mb_new_blocks(handle, &ar, errp);
642         if (count)
643                 *count = ar.len;
644         /*
645          * Account for the allocated meta blocks.  We will never
646          * fail EDQUOT for metdata, but we do account for it.
647          */
648         if (!(*errp) && (flags & EXT4_MB_DELALLOC_RESERVED)) {
649                 dquot_alloc_block_nofail(inode,
650                                 EXT4_C2B(EXT4_SB(inode->i_sb), ar.len));
651         }
652         return ret;
653 }
654
655 /**
656  * ext4_count_free_clusters() -- count filesystem free clusters
657  * @sb:         superblock
658  *
659  * Adds up the number of free clusters from each block group.
660  */
661 ext4_fsblk_t ext4_count_free_clusters(struct super_block *sb)
662 {
663         ext4_fsblk_t desc_count;
664         struct ext4_group_desc *gdp;
665         ext4_group_t i;
666         ext4_group_t ngroups = ext4_get_groups_count(sb);
667         struct ext4_group_info *grp;
668 #ifdef EXT4FS_DEBUG
669         struct ext4_super_block *es;
670         ext4_fsblk_t bitmap_count;
671         unsigned int x;
672         struct buffer_head *bitmap_bh = NULL;
673
674         es = EXT4_SB(sb)->s_es;
675         desc_count = 0;
676         bitmap_count = 0;
677         gdp = NULL;
678
679         for (i = 0; i < ngroups; i++) {
680                 gdp = ext4_get_group_desc(sb, i, NULL);
681                 if (!gdp)
682                         continue;
683                 grp = NULL;
684                 if (EXT4_SB(sb)->s_group_info)
685                         grp = ext4_get_group_info(sb, i);
686                 if (!grp || !EXT4_MB_GRP_BBITMAP_CORRUPT(grp))
687                         desc_count += ext4_free_group_clusters(sb, gdp);
688                 brelse(bitmap_bh);
689                 bitmap_bh = ext4_read_block_bitmap(sb, i);
690                 if (IS_ERR(bitmap_bh)) {
691                         bitmap_bh = NULL;
692                         continue;
693                 }
694
695                 x = ext4_count_free(bitmap_bh->b_data,
696                                     EXT4_CLUSTERS_PER_GROUP(sb) / 8);
697                 printk(KERN_DEBUG "group %u: stored = %d, counted = %u\n",
698                         i, ext4_free_group_clusters(sb, gdp), x);
699                 bitmap_count += x;
700         }
701         brelse(bitmap_bh);
702         printk(KERN_DEBUG "ext4_count_free_clusters: stored = %llu"
703                ", computed = %llu, %llu\n",
704                EXT4_NUM_B2C(EXT4_SB(sb), ext4_free_blocks_count(es)),
705                desc_count, bitmap_count);
706         return bitmap_count;
707 #else
708         desc_count = 0;
709         for (i = 0; i < ngroups; i++) {
710                 gdp = ext4_get_group_desc(sb, i, NULL);
711                 if (!gdp)
712                         continue;
713                 grp = NULL;
714                 if (EXT4_SB(sb)->s_group_info)
715                         grp = ext4_get_group_info(sb, i);
716                 if (!grp || !EXT4_MB_GRP_BBITMAP_CORRUPT(grp))
717                         desc_count += ext4_free_group_clusters(sb, gdp);
718         }
719
720         return desc_count;
721 #endif
722 }
723
724 static inline int test_root(ext4_group_t a, int b)
725 {
726         while (1) {
727                 if (a < b)
728                         return 0;
729                 if (a == b)
730                         return 1;
731                 if ((a % b) != 0)
732                         return 0;
733                 a = a / b;
734         }
735 }
736
737 /**
738  *      ext4_bg_has_super - number of blocks used by the superblock in group
739  *      @sb: superblock for filesystem
740  *      @group: group number to check
741  *
742  *      Return the number of blocks used by the superblock (primary or backup)
743  *      in this group.  Currently this will be only 0 or 1.
744  */
745 int ext4_bg_has_super(struct super_block *sb, ext4_group_t group)
746 {
747         struct ext4_super_block *es = EXT4_SB(sb)->s_es;
748
749         if (group == 0)
750                 return 1;
751         if (ext4_has_feature_sparse_super2(sb)) {
752                 if (group == le32_to_cpu(es->s_backup_bgs[0]) ||
753                     group == le32_to_cpu(es->s_backup_bgs[1]))
754                         return 1;
755                 return 0;
756         }
757         if ((group <= 1) || !ext4_has_feature_sparse_super(sb))
758                 return 1;
759         if (!(group & 1))
760                 return 0;
761         if (test_root(group, 3) || (test_root(group, 5)) ||
762             test_root(group, 7))
763                 return 1;
764
765         return 0;
766 }
767
768 static unsigned long ext4_bg_num_gdb_meta(struct super_block *sb,
769                                         ext4_group_t group)
770 {
771         unsigned long metagroup = group / EXT4_DESC_PER_BLOCK(sb);
772         ext4_group_t first = metagroup * EXT4_DESC_PER_BLOCK(sb);
773         ext4_group_t last = first + EXT4_DESC_PER_BLOCK(sb) - 1;
774
775         if (group == first || group == first + 1 || group == last)
776                 return 1;
777         return 0;
778 }
779
780 static unsigned long ext4_bg_num_gdb_nometa(struct super_block *sb,
781                                         ext4_group_t group)
782 {
783         if (!ext4_bg_has_super(sb, group))
784                 return 0;
785
786         if (ext4_has_feature_meta_bg(sb))
787                 return le32_to_cpu(EXT4_SB(sb)->s_es->s_first_meta_bg);
788         else
789                 return EXT4_SB(sb)->s_gdb_count;
790 }
791
792 /**
793  *      ext4_bg_num_gdb - number of blocks used by the group table in group
794  *      @sb: superblock for filesystem
795  *      @group: group number to check
796  *
797  *      Return the number of blocks used by the group descriptor table
798  *      (primary or backup) in this group.  In the future there may be a
799  *      different number of descriptor blocks in each group.
800  */
801 unsigned long ext4_bg_num_gdb(struct super_block *sb, ext4_group_t group)
802 {
803         unsigned long first_meta_bg =
804                         le32_to_cpu(EXT4_SB(sb)->s_es->s_first_meta_bg);
805         unsigned long metagroup = group / EXT4_DESC_PER_BLOCK(sb);
806
807         if (!ext4_has_feature_meta_bg(sb) || metagroup < first_meta_bg)
808                 return ext4_bg_num_gdb_nometa(sb, group);
809
810         return ext4_bg_num_gdb_meta(sb,group);
811
812 }
813
814 /*
815  * This function returns the number of file system metadata clusters at
816  * the beginning of a block group, including the reserved gdt blocks.
817  */
818 static unsigned ext4_num_base_meta_clusters(struct super_block *sb,
819                                      ext4_group_t block_group)
820 {
821         struct ext4_sb_info *sbi = EXT4_SB(sb);
822         unsigned num;
823
824         /* Check for superblock and gdt backups in this group */
825         num = ext4_bg_has_super(sb, block_group);
826
827         if (!ext4_has_feature_meta_bg(sb) ||
828             block_group < le32_to_cpu(sbi->s_es->s_first_meta_bg) *
829                           sbi->s_desc_per_block) {
830                 if (num) {
831                         num += ext4_bg_num_gdb(sb, block_group);
832                         num += le16_to_cpu(sbi->s_es->s_reserved_gdt_blocks);
833                 }
834         } else { /* For META_BG_BLOCK_GROUPS */
835                 num += ext4_bg_num_gdb(sb, block_group);
836         }
837         return EXT4_NUM_B2C(sbi, num);
838 }
839 /**
840  *      ext4_inode_to_goal_block - return a hint for block allocation
841  *      @inode: inode for block allocation
842  *
843  *      Return the ideal location to start allocating blocks for a
844  *      newly created inode.
845  */
846 ext4_fsblk_t ext4_inode_to_goal_block(struct inode *inode)
847 {
848         struct ext4_inode_info *ei = EXT4_I(inode);
849         ext4_group_t block_group;
850         ext4_grpblk_t colour;
851         int flex_size = ext4_flex_bg_size(EXT4_SB(inode->i_sb));
852         ext4_fsblk_t bg_start;
853         ext4_fsblk_t last_block;
854
855         block_group = ei->i_block_group;
856         if (flex_size >= EXT4_FLEX_SIZE_DIR_ALLOC_SCHEME) {
857                 /*
858                  * If there are at least EXT4_FLEX_SIZE_DIR_ALLOC_SCHEME
859                  * block groups per flexgroup, reserve the first block
860                  * group for directories and special files.  Regular
861                  * files will start at the second block group.  This
862                  * tends to speed up directory access and improves
863                  * fsck times.
864                  */
865                 block_group &= ~(flex_size-1);
866                 if (S_ISREG(inode->i_mode))
867                         block_group++;
868         }
869         bg_start = ext4_group_first_block_no(inode->i_sb, block_group);
870         last_block = ext4_blocks_count(EXT4_SB(inode->i_sb)->s_es) - 1;
871
872         /*
873          * If we are doing delayed allocation, we don't need take
874          * colour into account.
875          */
876         if (test_opt(inode->i_sb, DELALLOC))
877                 return bg_start;
878
879         if (bg_start + EXT4_BLOCKS_PER_GROUP(inode->i_sb) <= last_block)
880                 colour = (current->pid % 16) *
881                         (EXT4_BLOCKS_PER_GROUP(inode->i_sb) / 16);
882         else
883                 colour = (current->pid % 16) * ((last_block - bg_start) / 16);
884         return bg_start + colour;
885 }
886