Merge remote-tracking branch 'lsk/v3.10/topic/mailbox' into linux-linaro-lsk
[firefly-linux-kernel-4.4.55.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 static unsigned ext4_num_base_meta_clusters(struct super_block *sb,
27                                             ext4_group_t block_group);
28 /*
29  * balloc.c contains the blocks allocation and deallocation routines
30  */
31
32 /*
33  * Calculate block group number for a given block number
34  */
35 ext4_group_t ext4_get_group_number(struct super_block *sb,
36                                    ext4_fsblk_t block)
37 {
38         ext4_group_t group;
39
40         if (test_opt2(sb, STD_GROUP_SIZE))
41                 group = (block -
42                          le32_to_cpu(EXT4_SB(sb)->s_es->s_first_data_block)) >>
43                         (EXT4_BLOCK_SIZE_BITS(sb) + EXT4_CLUSTER_BITS(sb) + 3);
44         else
45                 ext4_get_group_no_and_offset(sb, block, &group, NULL);
46         return group;
47 }
48
49 /*
50  * Calculate the block group number and offset into the block/cluster
51  * allocation bitmap, given a block number
52  */
53 void ext4_get_group_no_and_offset(struct super_block *sb, ext4_fsblk_t blocknr,
54                 ext4_group_t *blockgrpp, ext4_grpblk_t *offsetp)
55 {
56         struct ext4_super_block *es = EXT4_SB(sb)->s_es;
57         ext4_grpblk_t offset;
58
59         blocknr = blocknr - le32_to_cpu(es->s_first_data_block);
60         offset = do_div(blocknr, EXT4_BLOCKS_PER_GROUP(sb)) >>
61                 EXT4_SB(sb)->s_cluster_bits;
62         if (offsetp)
63                 *offsetp = offset;
64         if (blockgrpp)
65                 *blockgrpp = blocknr;
66
67 }
68
69 /*
70  * Check whether the 'block' lives within the 'block_group'. Returns 1 if so
71  * and 0 otherwise.
72  */
73 static inline int ext4_block_in_group(struct super_block *sb,
74                                       ext4_fsblk_t block,
75                                       ext4_group_t block_group)
76 {
77         ext4_group_t actual_group;
78
79         actual_group = ext4_get_group_number(sb, block);
80         return (actual_group == block_group) ? 1 : 0;
81 }
82
83 /* Return the number of clusters used for file system metadata; this
84  * represents the overhead needed by the file system.
85  */
86 unsigned ext4_num_overhead_clusters(struct super_block *sb,
87                                     ext4_group_t block_group,
88                                     struct ext4_group_desc *gdp)
89 {
90         unsigned num_clusters;
91         int block_cluster = -1, inode_cluster = -1, itbl_cluster = -1, i, c;
92         ext4_fsblk_t start = ext4_group_first_block_no(sb, block_group);
93         ext4_fsblk_t itbl_blk;
94         struct ext4_sb_info *sbi = EXT4_SB(sb);
95
96         /* This is the number of clusters used by the superblock,
97          * block group descriptors, and reserved block group
98          * descriptor blocks */
99         num_clusters = ext4_num_base_meta_clusters(sb, block_group);
100
101         /*
102          * For the allocation bitmaps and inode table, we first need
103          * to check to see if the block is in the block group.  If it
104          * is, then check to see if the cluster is already accounted
105          * for in the clusters used for the base metadata cluster, or
106          * if we can increment the base metadata cluster to include
107          * that block.  Otherwise, we will have to track the cluster
108          * used for the allocation bitmap or inode table explicitly.
109          * Normally all of these blocks are contiguous, so the special
110          * case handling shouldn't be necessary except for *very*
111          * unusual file system layouts.
112          */
113         if (ext4_block_in_group(sb, ext4_block_bitmap(sb, gdp), block_group)) {
114                 block_cluster = EXT4_B2C(sbi,
115                                          ext4_block_bitmap(sb, gdp) - start);
116                 if (block_cluster < num_clusters)
117                         block_cluster = -1;
118                 else if (block_cluster == num_clusters) {
119                         num_clusters++;
120                         block_cluster = -1;
121                 }
122         }
123
124         if (ext4_block_in_group(sb, ext4_inode_bitmap(sb, gdp), block_group)) {
125                 inode_cluster = EXT4_B2C(sbi,
126                                          ext4_inode_bitmap(sb, gdp) - start);
127                 if (inode_cluster < num_clusters)
128                         inode_cluster = -1;
129                 else if (inode_cluster == num_clusters) {
130                         num_clusters++;
131                         inode_cluster = -1;
132                 }
133         }
134
135         itbl_blk = ext4_inode_table(sb, gdp);
136         for (i = 0; i < sbi->s_itb_per_group; i++) {
137                 if (ext4_block_in_group(sb, itbl_blk + i, block_group)) {
138                         c = EXT4_B2C(sbi, itbl_blk + i - start);
139                         if ((c < num_clusters) || (c == inode_cluster) ||
140                             (c == block_cluster) || (c == itbl_cluster))
141                                 continue;
142                         if (c == num_clusters) {
143                                 num_clusters++;
144                                 continue;
145                         }
146                         num_clusters++;
147                         itbl_cluster = c;
148                 }
149         }
150
151         if (block_cluster != -1)
152                 num_clusters++;
153         if (inode_cluster != -1)
154                 num_clusters++;
155
156         return num_clusters;
157 }
158
159 static unsigned int num_clusters_in_group(struct super_block *sb,
160                                           ext4_group_t block_group)
161 {
162         unsigned int blocks;
163
164         if (block_group == ext4_get_groups_count(sb) - 1) {
165                 /*
166                  * Even though mke2fs always initializes the first and
167                  * last group, just in case some other tool was used,
168                  * we need to make sure we calculate the right free
169                  * blocks.
170                  */
171                 blocks = ext4_blocks_count(EXT4_SB(sb)->s_es) -
172                         ext4_group_first_block_no(sb, block_group);
173         } else
174                 blocks = EXT4_BLOCKS_PER_GROUP(sb);
175         return EXT4_NUM_B2C(EXT4_SB(sb), blocks);
176 }
177
178 /* Initializes an uninitialized block bitmap */
179 void ext4_init_block_bitmap(struct super_block *sb, 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
188         J_ASSERT_BH(bh, buffer_locked(bh));
189
190         /* If checksum is bad mark all blocks used to prevent allocation
191          * essentially implementing a per-group read-only flag. */
192         if (!ext4_group_desc_csum_verify(sb, block_group, gdp)) {
193                 ext4_error(sb, "Checksum bad for group %u", block_group);
194                 ext4_free_group_clusters_set(sb, gdp, 0);
195                 ext4_free_inodes_set(sb, gdp, 0);
196                 ext4_itable_unused_set(sb, gdp, 0);
197                 memset(bh->b_data, 0xff, sb->s_blocksize);
198                 ext4_block_bitmap_csum_set(sb, block_group, gdp, bh);
199                 return;
200         }
201         memset(bh->b_data, 0, sb->s_blocksize);
202
203         bit_max = ext4_num_base_meta_clusters(sb, block_group);
204         for (bit = 0; bit < bit_max; bit++)
205                 ext4_set_bit(bit, bh->b_data);
206
207         start = ext4_group_first_block_no(sb, block_group);
208
209         if (EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_FLEX_BG))
210                 flex_bg = 1;
211
212         /* Set bits for block and inode bitmaps, and inode table */
213         tmp = ext4_block_bitmap(sb, gdp);
214         if (!flex_bg || ext4_block_in_group(sb, tmp, block_group))
215                 ext4_set_bit(EXT4_B2C(sbi, tmp - start), bh->b_data);
216
217         tmp = ext4_inode_bitmap(sb, gdp);
218         if (!flex_bg || ext4_block_in_group(sb, tmp, block_group))
219                 ext4_set_bit(EXT4_B2C(sbi, tmp - start), bh->b_data);
220
221         tmp = ext4_inode_table(sb, gdp);
222         for (; tmp < ext4_inode_table(sb, gdp) +
223                      sbi->s_itb_per_group; tmp++) {
224                 if (!flex_bg || ext4_block_in_group(sb, tmp, block_group))
225                         ext4_set_bit(EXT4_B2C(sbi, tmp - start), bh->b_data);
226         }
227
228         /*
229          * Also if the number of blocks within the group is less than
230          * the blocksize * 8 ( which is the size of bitmap ), set rest
231          * of the block bitmap to 1
232          */
233         ext4_mark_bitmap_end(num_clusters_in_group(sb, block_group),
234                              sb->s_blocksize * 8, bh->b_data);
235         ext4_block_bitmap_csum_set(sb, block_group, gdp, bh);
236         ext4_group_desc_csum_set(sb, block_group, gdp);
237 }
238
239 /* Return the number of free blocks in a block group.  It is used when
240  * the block bitmap is uninitialized, so we can't just count the bits
241  * in the bitmap. */
242 unsigned ext4_free_clusters_after_init(struct super_block *sb,
243                                        ext4_group_t block_group,
244                                        struct ext4_group_desc *gdp)
245 {
246         return num_clusters_in_group(sb, block_group) - 
247                 ext4_num_overhead_clusters(sb, block_group, gdp);
248 }
249
250 /*
251  * The free blocks are managed by bitmaps.  A file system contains several
252  * blocks groups.  Each group contains 1 bitmap block for blocks, 1 bitmap
253  * block for inodes, N blocks for the inode table and data blocks.
254  *
255  * The file system contains group descriptors which are located after the
256  * super block.  Each descriptor contains the number of the bitmap block and
257  * the free blocks count in the block.  The descriptors are loaded in memory
258  * when a file system is mounted (see ext4_fill_super).
259  */
260
261 /**
262  * ext4_get_group_desc() -- load group descriptor from disk
263  * @sb:                 super block
264  * @block_group:        given block group
265  * @bh:                 pointer to the buffer head to store the block
266  *                      group descriptor
267  */
268 struct ext4_group_desc * ext4_get_group_desc(struct super_block *sb,
269                                              ext4_group_t block_group,
270                                              struct buffer_head **bh)
271 {
272         unsigned int group_desc;
273         unsigned int offset;
274         ext4_group_t ngroups = ext4_get_groups_count(sb);
275         struct ext4_group_desc *desc;
276         struct ext4_sb_info *sbi = EXT4_SB(sb);
277
278         if (block_group >= ngroups) {
279                 ext4_error(sb, "block_group >= groups_count - block_group = %u,"
280                            " groups_count = %u", block_group, ngroups);
281
282                 return NULL;
283         }
284
285         group_desc = block_group >> EXT4_DESC_PER_BLOCK_BITS(sb);
286         offset = block_group & (EXT4_DESC_PER_BLOCK(sb) - 1);
287         if (!sbi->s_group_desc[group_desc]) {
288                 ext4_error(sb, "Group descriptor not loaded - "
289                            "block_group = %u, group_desc = %u, desc = %u",
290                            block_group, group_desc, offset);
291                 return NULL;
292         }
293
294         desc = (struct ext4_group_desc *)(
295                 (__u8 *)sbi->s_group_desc[group_desc]->b_data +
296                 offset * EXT4_DESC_SIZE(sb));
297         if (bh)
298                 *bh = sbi->s_group_desc[group_desc];
299         return desc;
300 }
301
302 /*
303  * Return the block number which was discovered to be invalid, or 0 if
304  * the block bitmap is valid.
305  */
306 static ext4_fsblk_t ext4_valid_block_bitmap(struct super_block *sb,
307                                             struct ext4_group_desc *desc,
308                                             unsigned int block_group,
309                                             struct buffer_head *bh)
310 {
311         ext4_grpblk_t offset;
312         ext4_grpblk_t next_zero_bit;
313         ext4_fsblk_t blk;
314         ext4_fsblk_t group_first_block;
315
316         if (EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_FLEX_BG)) {
317                 /* with FLEX_BG, the inode/block bitmaps and itable
318                  * blocks may not be in the group at all
319                  * so the bitmap validation will be skipped for those groups
320                  * or it has to also read the block group where the bitmaps
321                  * are located to verify they are set.
322                  */
323                 return 0;
324         }
325         group_first_block = ext4_group_first_block_no(sb, block_group);
326
327         /* check whether block bitmap block number is set */
328         blk = ext4_block_bitmap(sb, desc);
329         offset = blk - group_first_block;
330         if (!ext4_test_bit(offset, bh->b_data))
331                 /* bad block bitmap */
332                 return blk;
333
334         /* check whether the inode bitmap block number is set */
335         blk = ext4_inode_bitmap(sb, desc);
336         offset = blk - group_first_block;
337         if (!ext4_test_bit(offset, bh->b_data))
338                 /* bad block bitmap */
339                 return blk;
340
341         /* check whether the inode table block number is set */
342         blk = ext4_inode_table(sb, desc);
343         offset = blk - group_first_block;
344         next_zero_bit = ext4_find_next_zero_bit(bh->b_data,
345                                 offset + EXT4_SB(sb)->s_itb_per_group,
346                                 offset);
347         if (next_zero_bit < offset + EXT4_SB(sb)->s_itb_per_group)
348                 /* bad bitmap for inode tables */
349                 return blk;
350         return 0;
351 }
352
353 void ext4_validate_block_bitmap(struct super_block *sb,
354                                struct ext4_group_desc *desc,
355                                unsigned int block_group,
356                                struct buffer_head *bh)
357 {
358         ext4_fsblk_t    blk;
359
360         if (buffer_verified(bh))
361                 return;
362
363         ext4_lock_group(sb, block_group);
364         blk = ext4_valid_block_bitmap(sb, desc, block_group, bh);
365         if (unlikely(blk != 0)) {
366                 ext4_unlock_group(sb, block_group);
367                 ext4_error(sb, "bg %u: block %llu: invalid block bitmap",
368                            block_group, blk);
369                 return;
370         }
371         if (unlikely(!ext4_block_bitmap_csum_verify(sb, block_group,
372                         desc, bh))) {
373                 ext4_unlock_group(sb, block_group);
374                 ext4_error(sb, "bg %u: bad block bitmap checksum", block_group);
375                 return;
376         }
377         set_buffer_verified(bh);
378         ext4_unlock_group(sb, block_group);
379 }
380
381 /**
382  * ext4_read_block_bitmap_nowait()
383  * @sb:                 super block
384  * @block_group:        given block group
385  *
386  * Read the bitmap for a given block_group,and validate the
387  * bits for block/inode/inode tables are set in the bitmaps
388  *
389  * Return buffer_head on success or NULL in case of failure.
390  */
391 struct buffer_head *
392 ext4_read_block_bitmap_nowait(struct super_block *sb, ext4_group_t block_group)
393 {
394         struct ext4_group_desc *desc;
395         struct buffer_head *bh;
396         ext4_fsblk_t bitmap_blk;
397
398         desc = ext4_get_group_desc(sb, block_group, NULL);
399         if (!desc)
400                 return NULL;
401         bitmap_blk = ext4_block_bitmap(sb, desc);
402         bh = sb_getblk(sb, bitmap_blk);
403         if (unlikely(!bh)) {
404                 ext4_error(sb, "Cannot get buffer for block bitmap - "
405                            "block_group = %u, block_bitmap = %llu",
406                            block_group, bitmap_blk);
407                 return NULL;
408         }
409
410         if (bitmap_uptodate(bh))
411                 goto verify;
412
413         lock_buffer(bh);
414         if (bitmap_uptodate(bh)) {
415                 unlock_buffer(bh);
416                 goto verify;
417         }
418         ext4_lock_group(sb, block_group);
419         if (desc->bg_flags & cpu_to_le16(EXT4_BG_BLOCK_UNINIT)) {
420                 ext4_init_block_bitmap(sb, bh, block_group, desc);
421                 set_bitmap_uptodate(bh);
422                 set_buffer_uptodate(bh);
423                 ext4_unlock_group(sb, block_group);
424                 unlock_buffer(bh);
425                 return bh;
426         }
427         ext4_unlock_group(sb, block_group);
428         if (buffer_uptodate(bh)) {
429                 /*
430                  * if not uninit if bh is uptodate,
431                  * bitmap is also uptodate
432                  */
433                 set_bitmap_uptodate(bh);
434                 unlock_buffer(bh);
435                 goto verify;
436         }
437         /*
438          * submit the buffer_head for reading
439          */
440         set_buffer_new(bh);
441         trace_ext4_read_block_bitmap_load(sb, block_group);
442         bh->b_end_io = ext4_end_bitmap_read;
443         get_bh(bh);
444         submit_bh(READ | REQ_META | REQ_PRIO, bh);
445         return bh;
446 verify:
447         ext4_validate_block_bitmap(sb, desc, block_group, bh);
448         return bh;
449 }
450
451 /* Returns 0 on success, 1 on error */
452 int ext4_wait_block_bitmap(struct super_block *sb, ext4_group_t block_group,
453                            struct buffer_head *bh)
454 {
455         struct ext4_group_desc *desc;
456
457         if (!buffer_new(bh))
458                 return 0;
459         desc = ext4_get_group_desc(sb, block_group, NULL);
460         if (!desc)
461                 return 1;
462         wait_on_buffer(bh);
463         if (!buffer_uptodate(bh)) {
464                 ext4_error(sb, "Cannot read block bitmap - "
465                            "block_group = %u, block_bitmap = %llu",
466                            block_group, (unsigned long long) bh->b_blocknr);
467                 return 1;
468         }
469         clear_buffer_new(bh);
470         /* Panic or remount fs read-only if block bitmap is invalid */
471         ext4_validate_block_bitmap(sb, desc, block_group, bh);
472         return 0;
473 }
474
475 struct buffer_head *
476 ext4_read_block_bitmap(struct super_block *sb, ext4_group_t block_group)
477 {
478         struct buffer_head *bh;
479
480         bh = ext4_read_block_bitmap_nowait(sb, block_group);
481         if (!bh)
482                 return NULL;
483         if (ext4_wait_block_bitmap(sb, block_group, bh)) {
484                 put_bh(bh);
485                 return NULL;
486         }
487         return bh;
488 }
489
490 /**
491  * ext4_has_free_clusters()
492  * @sbi:        in-core super block structure.
493  * @nclusters:  number of needed blocks
494  * @flags:      flags from ext4_mb_new_blocks()
495  *
496  * Check if filesystem has nclusters free & available for allocation.
497  * On success return 1, return 0 on failure.
498  */
499 static int ext4_has_free_clusters(struct ext4_sb_info *sbi,
500                                   s64 nclusters, unsigned int flags)
501 {
502         s64 free_clusters, dirty_clusters, rsv, resv_clusters;
503         struct percpu_counter *fcc = &sbi->s_freeclusters_counter;
504         struct percpu_counter *dcc = &sbi->s_dirtyclusters_counter;
505
506         free_clusters  = percpu_counter_read_positive(fcc);
507         dirty_clusters = percpu_counter_read_positive(dcc);
508         resv_clusters = atomic64_read(&sbi->s_resv_clusters);
509
510         /*
511          * r_blocks_count should always be multiple of the cluster ratio so
512          * we are safe to do a plane bit shift only.
513          */
514         rsv = (ext4_r_blocks_count(sbi->s_es) >> sbi->s_cluster_bits) +
515               resv_clusters;
516
517         if (free_clusters - (nclusters + rsv + dirty_clusters) <
518                                         EXT4_FREECLUSTERS_WATERMARK) {
519                 free_clusters  = percpu_counter_sum_positive(fcc);
520                 dirty_clusters = percpu_counter_sum_positive(dcc);
521         }
522         /* Check whether we have space after accounting for current
523          * dirty clusters & root reserved clusters.
524          */
525         if (free_clusters >= (rsv + nclusters + dirty_clusters))
526                 return 1;
527
528         /* Hm, nope.  Are (enough) root reserved clusters available? */
529         if (uid_eq(sbi->s_resuid, current_fsuid()) ||
530             (!gid_eq(sbi->s_resgid, GLOBAL_ROOT_GID) && in_group_p(sbi->s_resgid)) ||
531             capable(CAP_SYS_RESOURCE) ||
532             (flags & EXT4_MB_USE_ROOT_BLOCKS)) {
533
534                 if (free_clusters >= (nclusters + dirty_clusters +
535                                       resv_clusters))
536                         return 1;
537         }
538         /* No free blocks. Let's see if we can dip into reserved pool */
539         if (flags & EXT4_MB_USE_RESERVED) {
540                 if (free_clusters >= (nclusters + dirty_clusters))
541                         return 1;
542         }
543
544         return 0;
545 }
546
547 int ext4_claim_free_clusters(struct ext4_sb_info *sbi,
548                              s64 nclusters, unsigned int flags)
549 {
550         if (ext4_has_free_clusters(sbi, nclusters, flags)) {
551                 percpu_counter_add(&sbi->s_dirtyclusters_counter, nclusters);
552                 return 0;
553         } else
554                 return -ENOSPC;
555 }
556
557 /**
558  * ext4_should_retry_alloc()
559  * @sb:                 super block
560  * @retries             number of attemps has been made
561  *
562  * ext4_should_retry_alloc() is called when ENOSPC is returned, and if
563  * it is profitable to retry the operation, this function will wait
564  * for the current or committing transaction to complete, and then
565  * return TRUE.
566  *
567  * if the total number of retries exceed three times, return FALSE.
568  */
569 int ext4_should_retry_alloc(struct super_block *sb, int *retries)
570 {
571         if (!ext4_has_free_clusters(EXT4_SB(sb), 1, 0) ||
572             (*retries)++ > 3 ||
573             !EXT4_SB(sb)->s_journal)
574                 return 0;
575
576         jbd_debug(1, "%s: retrying operation after ENOSPC\n", sb->s_id);
577
578         return jbd2_journal_force_commit_nested(EXT4_SB(sb)->s_journal);
579 }
580
581 /*
582  * ext4_new_meta_blocks() -- allocate block for meta data (indexing) blocks
583  *
584  * @handle:             handle to this transaction
585  * @inode:              file inode
586  * @goal:               given target block(filesystem wide)
587  * @count:              pointer to total number of clusters needed
588  * @errp:               error code
589  *
590  * Return 1st allocated block number on success, *count stores total account
591  * error stores in errp pointer
592  */
593 ext4_fsblk_t ext4_new_meta_blocks(handle_t *handle, struct inode *inode,
594                                   ext4_fsblk_t goal, unsigned int flags,
595                                   unsigned long *count, int *errp)
596 {
597         struct ext4_allocation_request ar;
598         ext4_fsblk_t ret;
599
600         memset(&ar, 0, sizeof(ar));
601         /* Fill with neighbour allocated blocks */
602         ar.inode = inode;
603         ar.goal = goal;
604         ar.len = count ? *count : 1;
605         ar.flags = flags;
606
607         ret = ext4_mb_new_blocks(handle, &ar, errp);
608         if (count)
609                 *count = ar.len;
610         /*
611          * Account for the allocated meta blocks.  We will never
612          * fail EDQUOT for metdata, but we do account for it.
613          */
614         if (!(*errp) &&
615             ext4_test_inode_state(inode, EXT4_STATE_DELALLOC_RESERVED)) {
616                 spin_lock(&EXT4_I(inode)->i_block_reservation_lock);
617                 EXT4_I(inode)->i_allocated_meta_blocks += ar.len;
618                 spin_unlock(&EXT4_I(inode)->i_block_reservation_lock);
619                 dquot_alloc_block_nofail(inode,
620                                 EXT4_C2B(EXT4_SB(inode->i_sb), ar.len));
621         }
622         return ret;
623 }
624
625 /**
626  * ext4_count_free_clusters() -- count filesystem free clusters
627  * @sb:         superblock
628  *
629  * Adds up the number of free clusters from each block group.
630  */
631 ext4_fsblk_t ext4_count_free_clusters(struct super_block *sb)
632 {
633         ext4_fsblk_t desc_count;
634         struct ext4_group_desc *gdp;
635         ext4_group_t i;
636         ext4_group_t ngroups = ext4_get_groups_count(sb);
637 #ifdef EXT4FS_DEBUG
638         struct ext4_super_block *es;
639         ext4_fsblk_t bitmap_count;
640         unsigned int x;
641         struct buffer_head *bitmap_bh = NULL;
642
643         es = EXT4_SB(sb)->s_es;
644         desc_count = 0;
645         bitmap_count = 0;
646         gdp = NULL;
647
648         for (i = 0; i < ngroups; i++) {
649                 gdp = ext4_get_group_desc(sb, i, NULL);
650                 if (!gdp)
651                         continue;
652                 desc_count += ext4_free_group_clusters(sb, gdp);
653                 brelse(bitmap_bh);
654                 bitmap_bh = ext4_read_block_bitmap(sb, i);
655                 if (bitmap_bh == NULL)
656                         continue;
657
658                 x = ext4_count_free(bitmap_bh->b_data,
659                                     EXT4_BLOCKS_PER_GROUP(sb) / 8);
660                 printk(KERN_DEBUG "group %u: stored = %d, counted = %u\n",
661                         i, ext4_free_group_clusters(sb, gdp), x);
662                 bitmap_count += x;
663         }
664         brelse(bitmap_bh);
665         printk(KERN_DEBUG "ext4_count_free_clusters: stored = %llu"
666                ", computed = %llu, %llu\n",
667                EXT4_NUM_B2C(EXT4_SB(sb), ext4_free_blocks_count(es)),
668                desc_count, bitmap_count);
669         return bitmap_count;
670 #else
671         desc_count = 0;
672         for (i = 0; i < ngroups; i++) {
673                 gdp = ext4_get_group_desc(sb, i, NULL);
674                 if (!gdp)
675                         continue;
676                 desc_count += ext4_free_group_clusters(sb, gdp);
677         }
678
679         return desc_count;
680 #endif
681 }
682
683 static inline int test_root(ext4_group_t a, int b)
684 {
685         int num = b;
686
687         while (a > num)
688                 num *= b;
689         return num == a;
690 }
691
692 static int ext4_group_sparse(ext4_group_t group)
693 {
694         if (group <= 1)
695                 return 1;
696         if (!(group & 1))
697                 return 0;
698         return (test_root(group, 7) || test_root(group, 5) ||
699                 test_root(group, 3));
700 }
701
702 /**
703  *      ext4_bg_has_super - number of blocks used by the superblock in group
704  *      @sb: superblock for filesystem
705  *      @group: group number to check
706  *
707  *      Return the number of blocks used by the superblock (primary or backup)
708  *      in this group.  Currently this will be only 0 or 1.
709  */
710 int ext4_bg_has_super(struct super_block *sb, ext4_group_t group)
711 {
712         if (EXT4_HAS_RO_COMPAT_FEATURE(sb,
713                                 EXT4_FEATURE_RO_COMPAT_SPARSE_SUPER) &&
714                         !ext4_group_sparse(group))
715                 return 0;
716         return 1;
717 }
718
719 static unsigned long ext4_bg_num_gdb_meta(struct super_block *sb,
720                                         ext4_group_t group)
721 {
722         unsigned long metagroup = group / EXT4_DESC_PER_BLOCK(sb);
723         ext4_group_t first = metagroup * EXT4_DESC_PER_BLOCK(sb);
724         ext4_group_t last = first + EXT4_DESC_PER_BLOCK(sb) - 1;
725
726         if (group == first || group == first + 1 || group == last)
727                 return 1;
728         return 0;
729 }
730
731 static unsigned long ext4_bg_num_gdb_nometa(struct super_block *sb,
732                                         ext4_group_t group)
733 {
734         if (!ext4_bg_has_super(sb, group))
735                 return 0;
736
737         if (EXT4_HAS_INCOMPAT_FEATURE(sb,EXT4_FEATURE_INCOMPAT_META_BG))
738                 return le32_to_cpu(EXT4_SB(sb)->s_es->s_first_meta_bg);
739         else
740                 return EXT4_SB(sb)->s_gdb_count;
741 }
742
743 /**
744  *      ext4_bg_num_gdb - number of blocks used by the group table in group
745  *      @sb: superblock for filesystem
746  *      @group: group number to check
747  *
748  *      Return the number of blocks used by the group descriptor table
749  *      (primary or backup) in this group.  In the future there may be a
750  *      different number of descriptor blocks in each group.
751  */
752 unsigned long ext4_bg_num_gdb(struct super_block *sb, ext4_group_t group)
753 {
754         unsigned long first_meta_bg =
755                         le32_to_cpu(EXT4_SB(sb)->s_es->s_first_meta_bg);
756         unsigned long metagroup = group / EXT4_DESC_PER_BLOCK(sb);
757
758         if (!EXT4_HAS_INCOMPAT_FEATURE(sb,EXT4_FEATURE_INCOMPAT_META_BG) ||
759                         metagroup < first_meta_bg)
760                 return ext4_bg_num_gdb_nometa(sb, group);
761
762         return ext4_bg_num_gdb_meta(sb,group);
763
764 }
765
766 /*
767  * This function returns the number of file system metadata clusters at
768  * the beginning of a block group, including the reserved gdt blocks.
769  */
770 static unsigned ext4_num_base_meta_clusters(struct super_block *sb,
771                                      ext4_group_t block_group)
772 {
773         struct ext4_sb_info *sbi = EXT4_SB(sb);
774         unsigned num;
775
776         /* Check for superblock and gdt backups in this group */
777         num = ext4_bg_has_super(sb, block_group);
778
779         if (!EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_META_BG) ||
780             block_group < le32_to_cpu(sbi->s_es->s_first_meta_bg) *
781                           sbi->s_desc_per_block) {
782                 if (num) {
783                         num += ext4_bg_num_gdb(sb, block_group);
784                         num += le16_to_cpu(sbi->s_es->s_reserved_gdt_blocks);
785                 }
786         } else { /* For META_BG_BLOCK_GROUPS */
787                 num += ext4_bg_num_gdb(sb, block_group);
788         }
789         return EXT4_NUM_B2C(sbi, num);
790 }
791 /**
792  *      ext4_inode_to_goal_block - return a hint for block allocation
793  *      @inode: inode for block allocation
794  *
795  *      Return the ideal location to start allocating blocks for a
796  *      newly created inode.
797  */
798 ext4_fsblk_t ext4_inode_to_goal_block(struct inode *inode)
799 {
800         struct ext4_inode_info *ei = EXT4_I(inode);
801         ext4_group_t block_group;
802         ext4_grpblk_t colour;
803         int flex_size = ext4_flex_bg_size(EXT4_SB(inode->i_sb));
804         ext4_fsblk_t bg_start;
805         ext4_fsblk_t last_block;
806
807         block_group = ei->i_block_group;
808         if (flex_size >= EXT4_FLEX_SIZE_DIR_ALLOC_SCHEME) {
809                 /*
810                  * If there are at least EXT4_FLEX_SIZE_DIR_ALLOC_SCHEME
811                  * block groups per flexgroup, reserve the first block
812                  * group for directories and special files.  Regular
813                  * files will start at the second block group.  This
814                  * tends to speed up directory access and improves
815                  * fsck times.
816                  */
817                 block_group &= ~(flex_size-1);
818                 if (S_ISREG(inode->i_mode))
819                         block_group++;
820         }
821         bg_start = ext4_group_first_block_no(inode->i_sb, block_group);
822         last_block = ext4_blocks_count(EXT4_SB(inode->i_sb)->s_es) - 1;
823
824         /*
825          * If we are doing delayed allocation, we don't need take
826          * colour into account.
827          */
828         if (test_opt(inode->i_sb, DELALLOC))
829                 return bg_start;
830
831         if (bg_start + EXT4_BLOCKS_PER_GROUP(inode->i_sb) <= last_block)
832                 colour = (current->pid % 16) *
833                         (EXT4_BLOCKS_PER_GROUP(inode->i_sb) / 16);
834         else
835                 colour = (current->pid % 16) * ((last_block - bg_start) / 16);
836         return bg_start + colour;
837 }
838