Loading...
1/*
2 * linux/fs/ext4/balloc.c
3 *
4 * Copyright (C) 1992, 1993, 1994, 1995
5 * Remy Card (card@masi.ibp.fr)
6 * Laboratoire MASI - Institut Blaise Pascal
7 * Universite Pierre et Marie Curie (Paris VI)
8 *
9 * Enhanced block allocation by Stephen Tweedie (sct@redhat.com), 1993
10 * Big-endian to little-endian byte-swapping/bitmaps by
11 * David S. Miller (davem@caip.rutgers.edu), 1995
12 */
13
14#include <linux/time.h>
15#include <linux/capability.h>
16#include <linux/fs.h>
17#include <linux/jbd2.h>
18#include <linux/quotaops.h>
19#include <linux/buffer_head.h>
20#include "ext4.h"
21#include "ext4_jbd2.h"
22#include "mballoc.h"
23
24#include <trace/events/ext4.h>
25
26/*
27 * balloc.c contains the blocks allocation and deallocation routines
28 */
29
30/*
31 * Calculate the block group number and offset, given a block number
32 */
33void ext4_get_group_no_and_offset(struct super_block *sb, ext4_fsblk_t blocknr,
34 ext4_group_t *blockgrpp, ext4_grpblk_t *offsetp)
35{
36 struct ext4_super_block *es = EXT4_SB(sb)->s_es;
37 ext4_grpblk_t offset;
38
39 blocknr = blocknr - le32_to_cpu(es->s_first_data_block);
40 offset = do_div(blocknr, EXT4_BLOCKS_PER_GROUP(sb));
41 if (offsetp)
42 *offsetp = offset;
43 if (blockgrpp)
44 *blockgrpp = blocknr;
45
46}
47
48static int ext4_block_in_group(struct super_block *sb, ext4_fsblk_t block,
49 ext4_group_t block_group)
50{
51 ext4_group_t actual_group;
52 ext4_get_group_no_and_offset(sb, block, &actual_group, NULL);
53 if (actual_group == block_group)
54 return 1;
55 return 0;
56}
57
58static int ext4_group_used_meta_blocks(struct super_block *sb,
59 ext4_group_t block_group,
60 struct ext4_group_desc *gdp)
61{
62 ext4_fsblk_t tmp;
63 struct ext4_sb_info *sbi = EXT4_SB(sb);
64 /* block bitmap, inode bitmap, and inode table blocks */
65 int used_blocks = sbi->s_itb_per_group + 2;
66
67 if (EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_FLEX_BG)) {
68 if (!ext4_block_in_group(sb, ext4_block_bitmap(sb, gdp),
69 block_group))
70 used_blocks--;
71
72 if (!ext4_block_in_group(sb, ext4_inode_bitmap(sb, gdp),
73 block_group))
74 used_blocks--;
75
76 tmp = ext4_inode_table(sb, gdp);
77 for (; tmp < ext4_inode_table(sb, gdp) +
78 sbi->s_itb_per_group; tmp++) {
79 if (!ext4_block_in_group(sb, tmp, block_group))
80 used_blocks -= 1;
81 }
82 }
83 return used_blocks;
84}
85
86/* Initializes an uninitialized block bitmap if given, and returns the
87 * number of blocks free in the group. */
88unsigned ext4_init_block_bitmap(struct super_block *sb, struct buffer_head *bh,
89 ext4_group_t block_group, struct ext4_group_desc *gdp)
90{
91 int bit, bit_max;
92 ext4_group_t ngroups = ext4_get_groups_count(sb);
93 unsigned free_blocks, group_blocks;
94 struct ext4_sb_info *sbi = EXT4_SB(sb);
95
96 if (bh) {
97 J_ASSERT_BH(bh, buffer_locked(bh));
98
99 /* If checksum is bad mark all blocks used to prevent allocation
100 * essentially implementing a per-group read-only flag. */
101 if (!ext4_group_desc_csum_verify(sbi, block_group, gdp)) {
102 ext4_error(sb, "Checksum bad for group %u",
103 block_group);
104 ext4_free_blks_set(sb, gdp, 0);
105 ext4_free_inodes_set(sb, gdp, 0);
106 ext4_itable_unused_set(sb, gdp, 0);
107 memset(bh->b_data, 0xff, sb->s_blocksize);
108 return 0;
109 }
110 memset(bh->b_data, 0, sb->s_blocksize);
111 }
112
113 /* Check for superblock and gdt backups in this group */
114 bit_max = ext4_bg_has_super(sb, block_group);
115
116 if (!EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_META_BG) ||
117 block_group < le32_to_cpu(sbi->s_es->s_first_meta_bg) *
118 sbi->s_desc_per_block) {
119 if (bit_max) {
120 bit_max += ext4_bg_num_gdb(sb, block_group);
121 bit_max +=
122 le16_to_cpu(sbi->s_es->s_reserved_gdt_blocks);
123 }
124 } else { /* For META_BG_BLOCK_GROUPS */
125 bit_max += ext4_bg_num_gdb(sb, block_group);
126 }
127
128 if (block_group == ngroups - 1) {
129 /*
130 * Even though mke2fs always initialize first and last group
131 * if some other tool enabled the EXT4_BG_BLOCK_UNINIT we need
132 * to make sure we calculate the right free blocks
133 */
134 group_blocks = ext4_blocks_count(sbi->s_es) -
135 ext4_group_first_block_no(sb, ngroups - 1);
136 } else {
137 group_blocks = EXT4_BLOCKS_PER_GROUP(sb);
138 }
139
140 free_blocks = group_blocks - bit_max;
141
142 if (bh) {
143 ext4_fsblk_t start, tmp;
144 int flex_bg = 0;
145
146 for (bit = 0; bit < bit_max; bit++)
147 ext4_set_bit(bit, bh->b_data);
148
149 start = ext4_group_first_block_no(sb, block_group);
150
151 if (EXT4_HAS_INCOMPAT_FEATURE(sb,
152 EXT4_FEATURE_INCOMPAT_FLEX_BG))
153 flex_bg = 1;
154
155 /* Set bits for block and inode bitmaps, and inode table */
156 tmp = ext4_block_bitmap(sb, gdp);
157 if (!flex_bg || ext4_block_in_group(sb, tmp, block_group))
158 ext4_set_bit(tmp - start, bh->b_data);
159
160 tmp = ext4_inode_bitmap(sb, gdp);
161 if (!flex_bg || ext4_block_in_group(sb, tmp, block_group))
162 ext4_set_bit(tmp - start, bh->b_data);
163
164 tmp = ext4_inode_table(sb, gdp);
165 for (; tmp < ext4_inode_table(sb, gdp) +
166 sbi->s_itb_per_group; tmp++) {
167 if (!flex_bg ||
168 ext4_block_in_group(sb, tmp, block_group))
169 ext4_set_bit(tmp - start, bh->b_data);
170 }
171 /*
172 * Also if the number of blocks within the group is
173 * less than the blocksize * 8 ( which is the size
174 * of bitmap ), set rest of the block bitmap to 1
175 */
176 ext4_mark_bitmap_end(group_blocks, sb->s_blocksize * 8,
177 bh->b_data);
178 }
179 return free_blocks - ext4_group_used_meta_blocks(sb, block_group, gdp);
180}
181
182
183/*
184 * The free blocks are managed by bitmaps. A file system contains several
185 * blocks groups. Each group contains 1 bitmap block for blocks, 1 bitmap
186 * block for inodes, N blocks for the inode table and data blocks.
187 *
188 * The file system contains group descriptors which are located after the
189 * super block. Each descriptor contains the number of the bitmap block and
190 * the free blocks count in the block. The descriptors are loaded in memory
191 * when a file system is mounted (see ext4_fill_super).
192 */
193
194/**
195 * ext4_get_group_desc() -- load group descriptor from disk
196 * @sb: super block
197 * @block_group: given block group
198 * @bh: pointer to the buffer head to store the block
199 * group descriptor
200 */
201struct ext4_group_desc * ext4_get_group_desc(struct super_block *sb,
202 ext4_group_t block_group,
203 struct buffer_head **bh)
204{
205 unsigned int group_desc;
206 unsigned int offset;
207 ext4_group_t ngroups = ext4_get_groups_count(sb);
208 struct ext4_group_desc *desc;
209 struct ext4_sb_info *sbi = EXT4_SB(sb);
210
211 if (block_group >= ngroups) {
212 ext4_error(sb, "block_group >= groups_count - block_group = %u,"
213 " groups_count = %u", block_group, ngroups);
214
215 return NULL;
216 }
217
218 group_desc = block_group >> EXT4_DESC_PER_BLOCK_BITS(sb);
219 offset = block_group & (EXT4_DESC_PER_BLOCK(sb) - 1);
220 if (!sbi->s_group_desc[group_desc]) {
221 ext4_error(sb, "Group descriptor not loaded - "
222 "block_group = %u, group_desc = %u, desc = %u",
223 block_group, group_desc, offset);
224 return NULL;
225 }
226
227 desc = (struct ext4_group_desc *)(
228 (__u8 *)sbi->s_group_desc[group_desc]->b_data +
229 offset * EXT4_DESC_SIZE(sb));
230 if (bh)
231 *bh = sbi->s_group_desc[group_desc];
232 return desc;
233}
234
235static int ext4_valid_block_bitmap(struct super_block *sb,
236 struct ext4_group_desc *desc,
237 unsigned int block_group,
238 struct buffer_head *bh)
239{
240 ext4_grpblk_t offset;
241 ext4_grpblk_t next_zero_bit;
242 ext4_fsblk_t bitmap_blk;
243 ext4_fsblk_t group_first_block;
244
245 if (EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_FLEX_BG)) {
246 /* with FLEX_BG, the inode/block bitmaps and itable
247 * blocks may not be in the group at all
248 * so the bitmap validation will be skipped for those groups
249 * or it has to also read the block group where the bitmaps
250 * are located to verify they are set.
251 */
252 return 1;
253 }
254 group_first_block = ext4_group_first_block_no(sb, block_group);
255
256 /* check whether block bitmap block number is set */
257 bitmap_blk = ext4_block_bitmap(sb, desc);
258 offset = bitmap_blk - group_first_block;
259 if (!ext4_test_bit(offset, bh->b_data))
260 /* bad block bitmap */
261 goto err_out;
262
263 /* check whether the inode bitmap block number is set */
264 bitmap_blk = ext4_inode_bitmap(sb, desc);
265 offset = bitmap_blk - group_first_block;
266 if (!ext4_test_bit(offset, bh->b_data))
267 /* bad block bitmap */
268 goto err_out;
269
270 /* check whether the inode table block number is set */
271 bitmap_blk = ext4_inode_table(sb, desc);
272 offset = bitmap_blk - group_first_block;
273 next_zero_bit = ext4_find_next_zero_bit(bh->b_data,
274 offset + EXT4_SB(sb)->s_itb_per_group,
275 offset);
276 if (next_zero_bit >= offset + EXT4_SB(sb)->s_itb_per_group)
277 /* good bitmap for inode tables */
278 return 1;
279
280err_out:
281 ext4_error(sb, "Invalid block bitmap - block_group = %d, block = %llu",
282 block_group, bitmap_blk);
283 return 0;
284}
285/**
286 * ext4_read_block_bitmap()
287 * @sb: super block
288 * @block_group: given block group
289 *
290 * Read the bitmap for a given block_group,and validate the
291 * bits for block/inode/inode tables are set in the bitmaps
292 *
293 * Return buffer_head on success or NULL in case of failure.
294 */
295struct buffer_head *
296ext4_read_block_bitmap(struct super_block *sb, ext4_group_t block_group)
297{
298 struct ext4_group_desc *desc;
299 struct buffer_head *bh = NULL;
300 ext4_fsblk_t bitmap_blk;
301
302 desc = ext4_get_group_desc(sb, block_group, NULL);
303 if (!desc)
304 return NULL;
305 bitmap_blk = ext4_block_bitmap(sb, desc);
306 bh = sb_getblk(sb, bitmap_blk);
307 if (unlikely(!bh)) {
308 ext4_error(sb, "Cannot read block bitmap - "
309 "block_group = %u, block_bitmap = %llu",
310 block_group, bitmap_blk);
311 return NULL;
312 }
313
314 if (bitmap_uptodate(bh))
315 return bh;
316
317 lock_buffer(bh);
318 if (bitmap_uptodate(bh)) {
319 unlock_buffer(bh);
320 return bh;
321 }
322 ext4_lock_group(sb, block_group);
323 if (desc->bg_flags & cpu_to_le16(EXT4_BG_BLOCK_UNINIT)) {
324 ext4_init_block_bitmap(sb, bh, block_group, desc);
325 set_bitmap_uptodate(bh);
326 set_buffer_uptodate(bh);
327 ext4_unlock_group(sb, block_group);
328 unlock_buffer(bh);
329 return bh;
330 }
331 ext4_unlock_group(sb, block_group);
332 if (buffer_uptodate(bh)) {
333 /*
334 * if not uninit if bh is uptodate,
335 * bitmap is also uptodate
336 */
337 set_bitmap_uptodate(bh);
338 unlock_buffer(bh);
339 return bh;
340 }
341 /*
342 * submit the buffer_head for read. We can
343 * safely mark the bitmap as uptodate now.
344 * We do it here so the bitmap uptodate bit
345 * get set with buffer lock held.
346 */
347 trace_ext4_read_block_bitmap_load(sb, block_group);
348 set_bitmap_uptodate(bh);
349 if (bh_submit_read(bh) < 0) {
350 put_bh(bh);
351 ext4_error(sb, "Cannot read block bitmap - "
352 "block_group = %u, block_bitmap = %llu",
353 block_group, bitmap_blk);
354 return NULL;
355 }
356 ext4_valid_block_bitmap(sb, desc, block_group, bh);
357 /*
358 * file system mounted not to panic on error,
359 * continue with corrupt bitmap
360 */
361 return bh;
362}
363
364/**
365 * ext4_has_free_blocks()
366 * @sbi: in-core super block structure.
367 * @nblocks: number of needed blocks
368 *
369 * Check if filesystem has nblocks free & available for allocation.
370 * On success return 1, return 0 on failure.
371 */
372static int ext4_has_free_blocks(struct ext4_sb_info *sbi,
373 s64 nblocks, unsigned int flags)
374{
375 s64 free_blocks, dirty_blocks, root_blocks;
376 struct percpu_counter *fbc = &sbi->s_freeblocks_counter;
377 struct percpu_counter *dbc = &sbi->s_dirtyblocks_counter;
378
379 free_blocks = percpu_counter_read_positive(fbc);
380 dirty_blocks = percpu_counter_read_positive(dbc);
381 root_blocks = ext4_r_blocks_count(sbi->s_es);
382
383 if (free_blocks - (nblocks + root_blocks + dirty_blocks) <
384 EXT4_FREEBLOCKS_WATERMARK) {
385 free_blocks = percpu_counter_sum_positive(fbc);
386 dirty_blocks = percpu_counter_sum_positive(dbc);
387 }
388 /* Check whether we have space after
389 * accounting for current dirty blocks & root reserved blocks.
390 */
391 if (free_blocks >= ((root_blocks + nblocks) + dirty_blocks))
392 return 1;
393
394 /* Hm, nope. Are (enough) root reserved blocks available? */
395 if (sbi->s_resuid == current_fsuid() ||
396 ((sbi->s_resgid != 0) && in_group_p(sbi->s_resgid)) ||
397 capable(CAP_SYS_RESOURCE) ||
398 (flags & EXT4_MB_USE_ROOT_BLOCKS)) {
399
400 if (free_blocks >= (nblocks + dirty_blocks))
401 return 1;
402 }
403
404 return 0;
405}
406
407int ext4_claim_free_blocks(struct ext4_sb_info *sbi,
408 s64 nblocks, unsigned int flags)
409{
410 if (ext4_has_free_blocks(sbi, nblocks, flags)) {
411 percpu_counter_add(&sbi->s_dirtyblocks_counter, nblocks);
412 return 0;
413 } else
414 return -ENOSPC;
415}
416
417/**
418 * ext4_should_retry_alloc()
419 * @sb: super block
420 * @retries number of attemps has been made
421 *
422 * ext4_should_retry_alloc() is called when ENOSPC is returned, and if
423 * it is profitable to retry the operation, this function will wait
424 * for the current or committing transaction to complete, and then
425 * return TRUE.
426 *
427 * if the total number of retries exceed three times, return FALSE.
428 */
429int ext4_should_retry_alloc(struct super_block *sb, int *retries)
430{
431 if (!ext4_has_free_blocks(EXT4_SB(sb), 1, 0) ||
432 (*retries)++ > 3 ||
433 !EXT4_SB(sb)->s_journal)
434 return 0;
435
436 jbd_debug(1, "%s: retrying operation after ENOSPC\n", sb->s_id);
437
438 return jbd2_journal_force_commit_nested(EXT4_SB(sb)->s_journal);
439}
440
441/*
442 * ext4_new_meta_blocks() -- allocate block for meta data (indexing) blocks
443 *
444 * @handle: handle to this transaction
445 * @inode: file inode
446 * @goal: given target block(filesystem wide)
447 * @count: pointer to total number of blocks needed
448 * @errp: error code
449 *
450 * Return 1st allocated block number on success, *count stores total account
451 * error stores in errp pointer
452 */
453ext4_fsblk_t ext4_new_meta_blocks(handle_t *handle, struct inode *inode,
454 ext4_fsblk_t goal, unsigned int flags,
455 unsigned long *count, int *errp)
456{
457 struct ext4_allocation_request ar;
458 ext4_fsblk_t ret;
459
460 memset(&ar, 0, sizeof(ar));
461 /* Fill with neighbour allocated blocks */
462 ar.inode = inode;
463 ar.goal = goal;
464 ar.len = count ? *count : 1;
465 ar.flags = flags;
466
467 ret = ext4_mb_new_blocks(handle, &ar, errp);
468 if (count)
469 *count = ar.len;
470 /*
471 * Account for the allocated meta blocks. We will never
472 * fail EDQUOT for metdata, but we do account for it.
473 */
474 if (!(*errp) &&
475 ext4_test_inode_state(inode, EXT4_STATE_DELALLOC_RESERVED)) {
476 spin_lock(&EXT4_I(inode)->i_block_reservation_lock);
477 EXT4_I(inode)->i_allocated_meta_blocks += ar.len;
478 spin_unlock(&EXT4_I(inode)->i_block_reservation_lock);
479 dquot_alloc_block_nofail(inode, ar.len);
480 }
481 return ret;
482}
483
484/**
485 * ext4_count_free_blocks() -- count filesystem free blocks
486 * @sb: superblock
487 *
488 * Adds up the number of free blocks from each block group.
489 */
490ext4_fsblk_t ext4_count_free_blocks(struct super_block *sb)
491{
492 ext4_fsblk_t desc_count;
493 struct ext4_group_desc *gdp;
494 ext4_group_t i;
495 ext4_group_t ngroups = ext4_get_groups_count(sb);
496#ifdef EXT4FS_DEBUG
497 struct ext4_super_block *es;
498 ext4_fsblk_t bitmap_count;
499 unsigned int x;
500 struct buffer_head *bitmap_bh = NULL;
501
502 es = EXT4_SB(sb)->s_es;
503 desc_count = 0;
504 bitmap_count = 0;
505 gdp = NULL;
506
507 for (i = 0; i < ngroups; i++) {
508 gdp = ext4_get_group_desc(sb, i, NULL);
509 if (!gdp)
510 continue;
511 desc_count += ext4_free_blks_count(sb, gdp);
512 brelse(bitmap_bh);
513 bitmap_bh = ext4_read_block_bitmap(sb, i);
514 if (bitmap_bh == NULL)
515 continue;
516
517 x = ext4_count_free(bitmap_bh, sb->s_blocksize);
518 printk(KERN_DEBUG "group %u: stored = %d, counted = %u\n",
519 i, ext4_free_blks_count(sb, gdp), x);
520 bitmap_count += x;
521 }
522 brelse(bitmap_bh);
523 printk(KERN_DEBUG "ext4_count_free_blocks: stored = %llu"
524 ", computed = %llu, %llu\n", ext4_free_blocks_count(es),
525 desc_count, bitmap_count);
526 return bitmap_count;
527#else
528 desc_count = 0;
529 for (i = 0; i < ngroups; i++) {
530 gdp = ext4_get_group_desc(sb, i, NULL);
531 if (!gdp)
532 continue;
533 desc_count += ext4_free_blks_count(sb, gdp);
534 }
535
536 return desc_count;
537#endif
538}
539
540static inline int test_root(ext4_group_t a, int b)
541{
542 int num = b;
543
544 while (a > num)
545 num *= b;
546 return num == a;
547}
548
549static int ext4_group_sparse(ext4_group_t group)
550{
551 if (group <= 1)
552 return 1;
553 if (!(group & 1))
554 return 0;
555 return (test_root(group, 7) || test_root(group, 5) ||
556 test_root(group, 3));
557}
558
559/**
560 * ext4_bg_has_super - number of blocks used by the superblock in group
561 * @sb: superblock for filesystem
562 * @group: group number to check
563 *
564 * Return the number of blocks used by the superblock (primary or backup)
565 * in this group. Currently this will be only 0 or 1.
566 */
567int ext4_bg_has_super(struct super_block *sb, ext4_group_t group)
568{
569 if (EXT4_HAS_RO_COMPAT_FEATURE(sb,
570 EXT4_FEATURE_RO_COMPAT_SPARSE_SUPER) &&
571 !ext4_group_sparse(group))
572 return 0;
573 return 1;
574}
575
576static unsigned long ext4_bg_num_gdb_meta(struct super_block *sb,
577 ext4_group_t group)
578{
579 unsigned long metagroup = group / EXT4_DESC_PER_BLOCK(sb);
580 ext4_group_t first = metagroup * EXT4_DESC_PER_BLOCK(sb);
581 ext4_group_t last = first + EXT4_DESC_PER_BLOCK(sb) - 1;
582
583 if (group == first || group == first + 1 || group == last)
584 return 1;
585 return 0;
586}
587
588static unsigned long ext4_bg_num_gdb_nometa(struct super_block *sb,
589 ext4_group_t group)
590{
591 if (!ext4_bg_has_super(sb, group))
592 return 0;
593
594 if (EXT4_HAS_INCOMPAT_FEATURE(sb,EXT4_FEATURE_INCOMPAT_META_BG))
595 return le32_to_cpu(EXT4_SB(sb)->s_es->s_first_meta_bg);
596 else
597 return EXT4_SB(sb)->s_gdb_count;
598}
599
600/**
601 * ext4_bg_num_gdb - number of blocks used by the group table in group
602 * @sb: superblock for filesystem
603 * @group: group number to check
604 *
605 * Return the number of blocks used by the group descriptor table
606 * (primary or backup) in this group. In the future there may be a
607 * different number of descriptor blocks in each group.
608 */
609unsigned long ext4_bg_num_gdb(struct super_block *sb, ext4_group_t group)
610{
611 unsigned long first_meta_bg =
612 le32_to_cpu(EXT4_SB(sb)->s_es->s_first_meta_bg);
613 unsigned long metagroup = group / EXT4_DESC_PER_BLOCK(sb);
614
615 if (!EXT4_HAS_INCOMPAT_FEATURE(sb,EXT4_FEATURE_INCOMPAT_META_BG) ||
616 metagroup < first_meta_bg)
617 return ext4_bg_num_gdb_nometa(sb, group);
618
619 return ext4_bg_num_gdb_meta(sb,group);
620
621}
622
623/**
624 * ext4_inode_to_goal_block - return a hint for block allocation
625 * @inode: inode for block allocation
626 *
627 * Return the ideal location to start allocating blocks for a
628 * newly created inode.
629 */
630ext4_fsblk_t ext4_inode_to_goal_block(struct inode *inode)
631{
632 struct ext4_inode_info *ei = EXT4_I(inode);
633 ext4_group_t block_group;
634 ext4_grpblk_t colour;
635 int flex_size = ext4_flex_bg_size(EXT4_SB(inode->i_sb));
636 ext4_fsblk_t bg_start;
637 ext4_fsblk_t last_block;
638
639 block_group = ei->i_block_group;
640 if (flex_size >= EXT4_FLEX_SIZE_DIR_ALLOC_SCHEME) {
641 /*
642 * If there are at least EXT4_FLEX_SIZE_DIR_ALLOC_SCHEME
643 * block groups per flexgroup, reserve the first block
644 * group for directories and special files. Regular
645 * files will start at the second block group. This
646 * tends to speed up directory access and improves
647 * fsck times.
648 */
649 block_group &= ~(flex_size-1);
650 if (S_ISREG(inode->i_mode))
651 block_group++;
652 }
653 bg_start = ext4_group_first_block_no(inode->i_sb, block_group);
654 last_block = ext4_blocks_count(EXT4_SB(inode->i_sb)->s_es) - 1;
655
656 /*
657 * If we are doing delayed allocation, we don't need take
658 * colour into account.
659 */
660 if (test_opt(inode->i_sb, DELALLOC))
661 return bg_start;
662
663 if (bg_start + EXT4_BLOCKS_PER_GROUP(inode->i_sb) <= last_block)
664 colour = (current->pid % 16) *
665 (EXT4_BLOCKS_PER_GROUP(inode->i_sb) / 16);
666 else
667 colour = (current->pid % 16) * ((last_block - bg_start) / 16);
668 return bg_start + colour;
669}
670
1// SPDX-License-Identifier: GPL-2.0
2/*
3 * linux/fs/ext4/balloc.c
4 *
5 * Copyright (C) 1992, 1993, 1994, 1995
6 * Remy Card (card@masi.ibp.fr)
7 * Laboratoire MASI - Institut Blaise Pascal
8 * Universite Pierre et Marie Curie (Paris VI)
9 *
10 * Enhanced block allocation by Stephen Tweedie (sct@redhat.com), 1993
11 * Big-endian to little-endian byte-swapping/bitmaps by
12 * David S. Miller (davem@caip.rutgers.edu), 1995
13 */
14
15#include <linux/time.h>
16#include <linux/capability.h>
17#include <linux/fs.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
26static 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 */
35ext4_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 */
53void 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 */
73static 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 */
86static 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
159static 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 */
179static int ext4_init_block_bitmap(struct super_block *sb,
180 struct buffer_head *bh,
181 ext4_group_t block_group,
182 struct ext4_group_desc *gdp)
183{
184 unsigned int bit, bit_max;
185 struct ext4_sb_info *sbi = EXT4_SB(sb);
186 ext4_fsblk_t start, tmp;
187 int flex_bg = 0;
188 struct ext4_group_info *grp;
189
190 J_ASSERT_BH(bh, buffer_locked(bh));
191
192 /* If checksum is bad mark all blocks used to prevent allocation
193 * essentially implementing a per-group read-only flag. */
194 if (!ext4_group_desc_csum_verify(sb, block_group, gdp)) {
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 if ((bit_max >> 3) >= bh->b_size)
213 return -EFSCORRUPTED;
214
215 for (bit = 0; bit < bit_max; bit++)
216 ext4_set_bit(bit, bh->b_data);
217
218 start = ext4_group_first_block_no(sb, block_group);
219
220 if (ext4_has_feature_flex_bg(sb))
221 flex_bg = 1;
222
223 /* Set bits for block and inode bitmaps, and inode table */
224 tmp = ext4_block_bitmap(sb, gdp);
225 if (!flex_bg || ext4_block_in_group(sb, tmp, block_group))
226 ext4_set_bit(EXT4_B2C(sbi, tmp - start), bh->b_data);
227
228 tmp = ext4_inode_bitmap(sb, gdp);
229 if (!flex_bg || ext4_block_in_group(sb, tmp, block_group))
230 ext4_set_bit(EXT4_B2C(sbi, tmp - start), bh->b_data);
231
232 tmp = ext4_inode_table(sb, gdp);
233 for (; tmp < ext4_inode_table(sb, gdp) +
234 sbi->s_itb_per_group; tmp++) {
235 if (!flex_bg || ext4_block_in_group(sb, tmp, block_group))
236 ext4_set_bit(EXT4_B2C(sbi, tmp - start), bh->b_data);
237 }
238
239 /*
240 * Also if the number of blocks within the group is less than
241 * the blocksize * 8 ( which is the size of bitmap ), set rest
242 * of the block bitmap to 1
243 */
244 ext4_mark_bitmap_end(num_clusters_in_group(sb, block_group),
245 sb->s_blocksize * 8, bh->b_data);
246 return 0;
247}
248
249/* Return the number of free blocks in a block group. It is used when
250 * the block bitmap is uninitialized, so we can't just count the bits
251 * in the bitmap. */
252unsigned ext4_free_clusters_after_init(struct super_block *sb,
253 ext4_group_t block_group,
254 struct ext4_group_desc *gdp)
255{
256 return num_clusters_in_group(sb, block_group) -
257 ext4_num_overhead_clusters(sb, block_group, gdp);
258}
259
260/*
261 * The free blocks are managed by bitmaps. A file system contains several
262 * blocks groups. Each group contains 1 bitmap block for blocks, 1 bitmap
263 * block for inodes, N blocks for the inode table and data blocks.
264 *
265 * The file system contains group descriptors which are located after the
266 * super block. Each descriptor contains the number of the bitmap block and
267 * the free blocks count in the block. The descriptors are loaded in memory
268 * when a file system is mounted (see ext4_fill_super).
269 */
270
271/**
272 * ext4_get_group_desc() -- load group descriptor from disk
273 * @sb: super block
274 * @block_group: given block group
275 * @bh: pointer to the buffer head to store the block
276 * group descriptor
277 */
278struct ext4_group_desc * ext4_get_group_desc(struct super_block *sb,
279 ext4_group_t block_group,
280 struct buffer_head **bh)
281{
282 unsigned int group_desc;
283 unsigned int offset;
284 ext4_group_t ngroups = ext4_get_groups_count(sb);
285 struct ext4_group_desc *desc;
286 struct ext4_sb_info *sbi = EXT4_SB(sb);
287
288 if (block_group >= ngroups) {
289 ext4_error(sb, "block_group >= groups_count - block_group = %u,"
290 " groups_count = %u", block_group, ngroups);
291
292 return NULL;
293 }
294
295 group_desc = block_group >> EXT4_DESC_PER_BLOCK_BITS(sb);
296 offset = block_group & (EXT4_DESC_PER_BLOCK(sb) - 1);
297 if (!sbi->s_group_desc[group_desc]) {
298 ext4_error(sb, "Group descriptor not loaded - "
299 "block_group = %u, group_desc = %u, desc = %u",
300 block_group, group_desc, offset);
301 return NULL;
302 }
303
304 desc = (struct ext4_group_desc *)(
305 (__u8 *)sbi->s_group_desc[group_desc]->b_data +
306 offset * EXT4_DESC_SIZE(sb));
307 if (bh)
308 *bh = sbi->s_group_desc[group_desc];
309 return desc;
310}
311
312/*
313 * Return the block number which was discovered to be invalid, or 0 if
314 * the block bitmap is valid.
315 */
316static ext4_fsblk_t ext4_valid_block_bitmap(struct super_block *sb,
317 struct ext4_group_desc *desc,
318 ext4_group_t block_group,
319 struct buffer_head *bh)
320{
321 struct ext4_sb_info *sbi = EXT4_SB(sb);
322 ext4_grpblk_t offset;
323 ext4_grpblk_t next_zero_bit;
324 ext4_grpblk_t max_bit = EXT4_CLUSTERS_PER_GROUP(sb);
325 ext4_fsblk_t blk;
326 ext4_fsblk_t group_first_block;
327
328 if (ext4_has_feature_flex_bg(sb)) {
329 /* with FLEX_BG, the inode/block bitmaps and itable
330 * blocks may not be in the group at all
331 * so the bitmap validation will be skipped for those groups
332 * or it has to also read the block group where the bitmaps
333 * are located to verify they are set.
334 */
335 return 0;
336 }
337 group_first_block = ext4_group_first_block_no(sb, block_group);
338
339 /* check whether block bitmap block number is set */
340 blk = ext4_block_bitmap(sb, desc);
341 offset = blk - group_first_block;
342 if (offset < 0 || EXT4_B2C(sbi, offset) >= max_bit ||
343 !ext4_test_bit(EXT4_B2C(sbi, offset), bh->b_data))
344 /* bad block bitmap */
345 return blk;
346
347 /* check whether the inode bitmap block number is set */
348 blk = ext4_inode_bitmap(sb, desc);
349 offset = blk - group_first_block;
350 if (offset < 0 || EXT4_B2C(sbi, offset) >= max_bit ||
351 !ext4_test_bit(EXT4_B2C(sbi, offset), bh->b_data))
352 /* bad block bitmap */
353 return blk;
354
355 /* check whether the inode table block number is set */
356 blk = ext4_inode_table(sb, desc);
357 offset = blk - group_first_block;
358 if (offset < 0 || EXT4_B2C(sbi, offset) >= max_bit ||
359 EXT4_B2C(sbi, offset + sbi->s_itb_per_group) >= max_bit)
360 return blk;
361 next_zero_bit = ext4_find_next_zero_bit(bh->b_data,
362 EXT4_B2C(sbi, offset + sbi->s_itb_per_group),
363 EXT4_B2C(sbi, offset));
364 if (next_zero_bit <
365 EXT4_B2C(sbi, offset + sbi->s_itb_per_group))
366 /* bad bitmap for inode tables */
367 return blk;
368 return 0;
369}
370
371static int ext4_validate_block_bitmap(struct super_block *sb,
372 struct ext4_group_desc *desc,
373 ext4_group_t block_group,
374 struct buffer_head *bh)
375{
376 ext4_fsblk_t blk;
377 struct ext4_group_info *grp = ext4_get_group_info(sb, block_group);
378 struct ext4_sb_info *sbi = EXT4_SB(sb);
379
380 if (buffer_verified(bh))
381 return 0;
382 if (EXT4_MB_GRP_BBITMAP_CORRUPT(grp))
383 return -EFSCORRUPTED;
384
385 ext4_lock_group(sb, block_group);
386 if (unlikely(!ext4_block_bitmap_csum_verify(sb, block_group,
387 desc, bh))) {
388 ext4_unlock_group(sb, block_group);
389 ext4_error(sb, "bg %u: bad block bitmap checksum", block_group);
390 if (!EXT4_MB_GRP_BBITMAP_CORRUPT(grp))
391 percpu_counter_sub(&sbi->s_freeclusters_counter,
392 grp->bb_free);
393 set_bit(EXT4_GROUP_INFO_BBITMAP_CORRUPT_BIT, &grp->bb_state);
394 return -EFSBADCRC;
395 }
396 blk = ext4_valid_block_bitmap(sb, desc, block_group, bh);
397 if (unlikely(blk != 0)) {
398 ext4_unlock_group(sb, block_group);
399 ext4_error(sb, "bg %u: block %llu: invalid block bitmap",
400 block_group, blk);
401 if (!EXT4_MB_GRP_BBITMAP_CORRUPT(grp))
402 percpu_counter_sub(&sbi->s_freeclusters_counter,
403 grp->bb_free);
404 set_bit(EXT4_GROUP_INFO_BBITMAP_CORRUPT_BIT, &grp->bb_state);
405 return -EFSCORRUPTED;
406 }
407 set_buffer_verified(bh);
408 ext4_unlock_group(sb, block_group);
409 return 0;
410}
411
412/**
413 * ext4_read_block_bitmap_nowait()
414 * @sb: super block
415 * @block_group: given block group
416 *
417 * Read the bitmap for a given block_group,and validate the
418 * bits for block/inode/inode tables are set in the bitmaps
419 *
420 * Return buffer_head on success or NULL in case of failure.
421 */
422struct buffer_head *
423ext4_read_block_bitmap_nowait(struct super_block *sb, ext4_group_t block_group)
424{
425 struct ext4_group_desc *desc;
426 struct ext4_sb_info *sbi = EXT4_SB(sb);
427 struct buffer_head *bh;
428 ext4_fsblk_t bitmap_blk;
429 int err;
430
431 desc = ext4_get_group_desc(sb, block_group, NULL);
432 if (!desc)
433 return ERR_PTR(-EFSCORRUPTED);
434 bitmap_blk = ext4_block_bitmap(sb, desc);
435 if ((bitmap_blk <= le32_to_cpu(sbi->s_es->s_first_data_block)) ||
436 (bitmap_blk >= ext4_blocks_count(sbi->s_es))) {
437 ext4_error(sb, "Invalid block bitmap block %llu in "
438 "block_group %u", bitmap_blk, block_group);
439 return ERR_PTR(-EFSCORRUPTED);
440 }
441 bh = sb_getblk(sb, bitmap_blk);
442 if (unlikely(!bh)) {
443 ext4_error(sb, "Cannot get buffer for block bitmap - "
444 "block_group = %u, block_bitmap = %llu",
445 block_group, bitmap_blk);
446 return ERR_PTR(-ENOMEM);
447 }
448
449 if (bitmap_uptodate(bh))
450 goto verify;
451
452 lock_buffer(bh);
453 if (bitmap_uptodate(bh)) {
454 unlock_buffer(bh);
455 goto verify;
456 }
457 ext4_lock_group(sb, block_group);
458 if (desc->bg_flags & cpu_to_le16(EXT4_BG_BLOCK_UNINIT)) {
459 err = ext4_init_block_bitmap(sb, bh, block_group, desc);
460 set_bitmap_uptodate(bh);
461 set_buffer_uptodate(bh);
462 set_buffer_verified(bh);
463 ext4_unlock_group(sb, block_group);
464 unlock_buffer(bh);
465 if (err) {
466 ext4_error(sb, "Failed to init block bitmap for group "
467 "%u: %d", block_group, err);
468 goto out;
469 }
470 goto verify;
471 }
472 ext4_unlock_group(sb, block_group);
473 if (buffer_uptodate(bh)) {
474 /*
475 * if not uninit if bh is uptodate,
476 * bitmap is also uptodate
477 */
478 set_bitmap_uptodate(bh);
479 unlock_buffer(bh);
480 goto verify;
481 }
482 /*
483 * submit the buffer_head for reading
484 */
485 set_buffer_new(bh);
486 trace_ext4_read_block_bitmap_load(sb, block_group);
487 bh->b_end_io = ext4_end_bitmap_read;
488 get_bh(bh);
489 submit_bh(REQ_OP_READ, REQ_META | REQ_PRIO, bh);
490 return bh;
491verify:
492 err = ext4_validate_block_bitmap(sb, desc, block_group, bh);
493 if (err)
494 goto out;
495 return bh;
496out:
497 put_bh(bh);
498 return ERR_PTR(err);
499}
500
501/* Returns 0 on success, 1 on error */
502int ext4_wait_block_bitmap(struct super_block *sb, ext4_group_t block_group,
503 struct buffer_head *bh)
504{
505 struct ext4_group_desc *desc;
506
507 if (!buffer_new(bh))
508 return 0;
509 desc = ext4_get_group_desc(sb, block_group, NULL);
510 if (!desc)
511 return -EFSCORRUPTED;
512 wait_on_buffer(bh);
513 if (!buffer_uptodate(bh)) {
514 ext4_error(sb, "Cannot read block bitmap - "
515 "block_group = %u, block_bitmap = %llu",
516 block_group, (unsigned long long) bh->b_blocknr);
517 return -EIO;
518 }
519 clear_buffer_new(bh);
520 /* Panic or remount fs read-only if block bitmap is invalid */
521 return ext4_validate_block_bitmap(sb, desc, block_group, bh);
522}
523
524struct buffer_head *
525ext4_read_block_bitmap(struct super_block *sb, ext4_group_t block_group)
526{
527 struct buffer_head *bh;
528 int err;
529
530 bh = ext4_read_block_bitmap_nowait(sb, block_group);
531 if (IS_ERR(bh))
532 return bh;
533 err = ext4_wait_block_bitmap(sb, block_group, bh);
534 if (err) {
535 put_bh(bh);
536 return ERR_PTR(err);
537 }
538 return bh;
539}
540
541/**
542 * ext4_has_free_clusters()
543 * @sbi: in-core super block structure.
544 * @nclusters: number of needed blocks
545 * @flags: flags from ext4_mb_new_blocks()
546 *
547 * Check if filesystem has nclusters free & available for allocation.
548 * On success return 1, return 0 on failure.
549 */
550static int ext4_has_free_clusters(struct ext4_sb_info *sbi,
551 s64 nclusters, unsigned int flags)
552{
553 s64 free_clusters, dirty_clusters, rsv, resv_clusters;
554 struct percpu_counter *fcc = &sbi->s_freeclusters_counter;
555 struct percpu_counter *dcc = &sbi->s_dirtyclusters_counter;
556
557 free_clusters = percpu_counter_read_positive(fcc);
558 dirty_clusters = percpu_counter_read_positive(dcc);
559 resv_clusters = atomic64_read(&sbi->s_resv_clusters);
560
561 /*
562 * r_blocks_count should always be multiple of the cluster ratio so
563 * we are safe to do a plane bit shift only.
564 */
565 rsv = (ext4_r_blocks_count(sbi->s_es) >> sbi->s_cluster_bits) +
566 resv_clusters;
567
568 if (free_clusters - (nclusters + rsv + dirty_clusters) <
569 EXT4_FREECLUSTERS_WATERMARK) {
570 free_clusters = percpu_counter_sum_positive(fcc);
571 dirty_clusters = percpu_counter_sum_positive(dcc);
572 }
573 /* Check whether we have space after accounting for current
574 * dirty clusters & root reserved clusters.
575 */
576 if (free_clusters >= (rsv + nclusters + dirty_clusters))
577 return 1;
578
579 /* Hm, nope. Are (enough) root reserved clusters available? */
580 if (uid_eq(sbi->s_resuid, current_fsuid()) ||
581 (!gid_eq(sbi->s_resgid, GLOBAL_ROOT_GID) && in_group_p(sbi->s_resgid)) ||
582 capable(CAP_SYS_RESOURCE) ||
583 (flags & EXT4_MB_USE_ROOT_BLOCKS)) {
584
585 if (free_clusters >= (nclusters + dirty_clusters +
586 resv_clusters))
587 return 1;
588 }
589 /* No free blocks. Let's see if we can dip into reserved pool */
590 if (flags & EXT4_MB_USE_RESERVED) {
591 if (free_clusters >= (nclusters + dirty_clusters))
592 return 1;
593 }
594
595 return 0;
596}
597
598int ext4_claim_free_clusters(struct ext4_sb_info *sbi,
599 s64 nclusters, unsigned int flags)
600{
601 if (ext4_has_free_clusters(sbi, nclusters, flags)) {
602 percpu_counter_add(&sbi->s_dirtyclusters_counter, nclusters);
603 return 0;
604 } else
605 return -ENOSPC;
606}
607
608/**
609 * ext4_should_retry_alloc()
610 * @sb: super block
611 * @retries number of attemps has been made
612 *
613 * ext4_should_retry_alloc() is called when ENOSPC is returned, and if
614 * it is profitable to retry the operation, this function will wait
615 * for the current or committing transaction to complete, and then
616 * return TRUE. We will only retry once.
617 */
618int ext4_should_retry_alloc(struct super_block *sb, int *retries)
619{
620 if (!ext4_has_free_clusters(EXT4_SB(sb), 1, 0) ||
621 (*retries)++ > 1 ||
622 !EXT4_SB(sb)->s_journal)
623 return 0;
624
625 smp_mb();
626 if (EXT4_SB(sb)->s_mb_free_pending == 0)
627 return 0;
628
629 jbd_debug(1, "%s: retrying operation after ENOSPC\n", sb->s_id);
630 jbd2_journal_force_commit_nested(EXT4_SB(sb)->s_journal);
631 return 1;
632}
633
634/*
635 * ext4_new_meta_blocks() -- allocate block for meta data (indexing) blocks
636 *
637 * @handle: handle to this transaction
638 * @inode: file inode
639 * @goal: given target block(filesystem wide)
640 * @count: pointer to total number of clusters needed
641 * @errp: error code
642 *
643 * Return 1st allocated block number on success, *count stores total account
644 * error stores in errp pointer
645 */
646ext4_fsblk_t ext4_new_meta_blocks(handle_t *handle, struct inode *inode,
647 ext4_fsblk_t goal, unsigned int flags,
648 unsigned long *count, int *errp)
649{
650 struct ext4_allocation_request ar;
651 ext4_fsblk_t ret;
652
653 memset(&ar, 0, sizeof(ar));
654 /* Fill with neighbour allocated blocks */
655 ar.inode = inode;
656 ar.goal = goal;
657 ar.len = count ? *count : 1;
658 ar.flags = flags;
659
660 ret = ext4_mb_new_blocks(handle, &ar, errp);
661 if (count)
662 *count = ar.len;
663 /*
664 * Account for the allocated meta blocks. We will never
665 * fail EDQUOT for metdata, but we do account for it.
666 */
667 if (!(*errp) && (flags & EXT4_MB_DELALLOC_RESERVED)) {
668 dquot_alloc_block_nofail(inode,
669 EXT4_C2B(EXT4_SB(inode->i_sb), ar.len));
670 }
671 return ret;
672}
673
674/**
675 * ext4_count_free_clusters() -- count filesystem free clusters
676 * @sb: superblock
677 *
678 * Adds up the number of free clusters from each block group.
679 */
680ext4_fsblk_t ext4_count_free_clusters(struct super_block *sb)
681{
682 ext4_fsblk_t desc_count;
683 struct ext4_group_desc *gdp;
684 ext4_group_t i;
685 ext4_group_t ngroups = ext4_get_groups_count(sb);
686 struct ext4_group_info *grp;
687#ifdef EXT4FS_DEBUG
688 struct ext4_super_block *es;
689 ext4_fsblk_t bitmap_count;
690 unsigned int x;
691 struct buffer_head *bitmap_bh = NULL;
692
693 es = EXT4_SB(sb)->s_es;
694 desc_count = 0;
695 bitmap_count = 0;
696 gdp = NULL;
697
698 for (i = 0; i < ngroups; i++) {
699 gdp = ext4_get_group_desc(sb, i, NULL);
700 if (!gdp)
701 continue;
702 grp = NULL;
703 if (EXT4_SB(sb)->s_group_info)
704 grp = ext4_get_group_info(sb, i);
705 if (!grp || !EXT4_MB_GRP_BBITMAP_CORRUPT(grp))
706 desc_count += ext4_free_group_clusters(sb, gdp);
707 brelse(bitmap_bh);
708 bitmap_bh = ext4_read_block_bitmap(sb, i);
709 if (IS_ERR(bitmap_bh)) {
710 bitmap_bh = NULL;
711 continue;
712 }
713
714 x = ext4_count_free(bitmap_bh->b_data,
715 EXT4_CLUSTERS_PER_GROUP(sb) / 8);
716 printk(KERN_DEBUG "group %u: stored = %d, counted = %u\n",
717 i, ext4_free_group_clusters(sb, gdp), x);
718 bitmap_count += x;
719 }
720 brelse(bitmap_bh);
721 printk(KERN_DEBUG "ext4_count_free_clusters: stored = %llu"
722 ", computed = %llu, %llu\n",
723 EXT4_NUM_B2C(EXT4_SB(sb), ext4_free_blocks_count(es)),
724 desc_count, bitmap_count);
725 return bitmap_count;
726#else
727 desc_count = 0;
728 for (i = 0; i < ngroups; i++) {
729 gdp = ext4_get_group_desc(sb, i, NULL);
730 if (!gdp)
731 continue;
732 grp = NULL;
733 if (EXT4_SB(sb)->s_group_info)
734 grp = ext4_get_group_info(sb, i);
735 if (!grp || !EXT4_MB_GRP_BBITMAP_CORRUPT(grp))
736 desc_count += ext4_free_group_clusters(sb, gdp);
737 }
738
739 return desc_count;
740#endif
741}
742
743static inline int test_root(ext4_group_t a, int b)
744{
745 while (1) {
746 if (a < b)
747 return 0;
748 if (a == b)
749 return 1;
750 if ((a % b) != 0)
751 return 0;
752 a = a / b;
753 }
754}
755
756/**
757 * ext4_bg_has_super - number of blocks used by the superblock in group
758 * @sb: superblock for filesystem
759 * @group: group number to check
760 *
761 * Return the number of blocks used by the superblock (primary or backup)
762 * in this group. Currently this will be only 0 or 1.
763 */
764int ext4_bg_has_super(struct super_block *sb, ext4_group_t group)
765{
766 struct ext4_super_block *es = EXT4_SB(sb)->s_es;
767
768 if (group == 0)
769 return 1;
770 if (ext4_has_feature_sparse_super2(sb)) {
771 if (group == le32_to_cpu(es->s_backup_bgs[0]) ||
772 group == le32_to_cpu(es->s_backup_bgs[1]))
773 return 1;
774 return 0;
775 }
776 if ((group <= 1) || !ext4_has_feature_sparse_super(sb))
777 return 1;
778 if (!(group & 1))
779 return 0;
780 if (test_root(group, 3) || (test_root(group, 5)) ||
781 test_root(group, 7))
782 return 1;
783
784 return 0;
785}
786
787static unsigned long ext4_bg_num_gdb_meta(struct super_block *sb,
788 ext4_group_t group)
789{
790 unsigned long metagroup = group / EXT4_DESC_PER_BLOCK(sb);
791 ext4_group_t first = metagroup * EXT4_DESC_PER_BLOCK(sb);
792 ext4_group_t last = first + EXT4_DESC_PER_BLOCK(sb) - 1;
793
794 if (group == first || group == first + 1 || group == last)
795 return 1;
796 return 0;
797}
798
799static unsigned long ext4_bg_num_gdb_nometa(struct super_block *sb,
800 ext4_group_t group)
801{
802 if (!ext4_bg_has_super(sb, group))
803 return 0;
804
805 if (ext4_has_feature_meta_bg(sb))
806 return le32_to_cpu(EXT4_SB(sb)->s_es->s_first_meta_bg);
807 else
808 return EXT4_SB(sb)->s_gdb_count;
809}
810
811/**
812 * ext4_bg_num_gdb - number of blocks used by the group table in group
813 * @sb: superblock for filesystem
814 * @group: group number to check
815 *
816 * Return the number of blocks used by the group descriptor table
817 * (primary or backup) in this group. In the future there may be a
818 * different number of descriptor blocks in each group.
819 */
820unsigned long ext4_bg_num_gdb(struct super_block *sb, ext4_group_t group)
821{
822 unsigned long first_meta_bg =
823 le32_to_cpu(EXT4_SB(sb)->s_es->s_first_meta_bg);
824 unsigned long metagroup = group / EXT4_DESC_PER_BLOCK(sb);
825
826 if (!ext4_has_feature_meta_bg(sb) || metagroup < first_meta_bg)
827 return ext4_bg_num_gdb_nometa(sb, group);
828
829 return ext4_bg_num_gdb_meta(sb,group);
830
831}
832
833/*
834 * This function returns the number of file system metadata clusters at
835 * the beginning of a block group, including the reserved gdt blocks.
836 */
837static unsigned ext4_num_base_meta_clusters(struct super_block *sb,
838 ext4_group_t block_group)
839{
840 struct ext4_sb_info *sbi = EXT4_SB(sb);
841 unsigned num;
842
843 /* Check for superblock and gdt backups in this group */
844 num = ext4_bg_has_super(sb, block_group);
845
846 if (!ext4_has_feature_meta_bg(sb) ||
847 block_group < le32_to_cpu(sbi->s_es->s_first_meta_bg) *
848 sbi->s_desc_per_block) {
849 if (num) {
850 num += ext4_bg_num_gdb(sb, block_group);
851 num += le16_to_cpu(sbi->s_es->s_reserved_gdt_blocks);
852 }
853 } else { /* For META_BG_BLOCK_GROUPS */
854 num += ext4_bg_num_gdb(sb, block_group);
855 }
856 return EXT4_NUM_B2C(sbi, num);
857}
858/**
859 * ext4_inode_to_goal_block - return a hint for block allocation
860 * @inode: inode for block allocation
861 *
862 * Return the ideal location to start allocating blocks for a
863 * newly created inode.
864 */
865ext4_fsblk_t ext4_inode_to_goal_block(struct inode *inode)
866{
867 struct ext4_inode_info *ei = EXT4_I(inode);
868 ext4_group_t block_group;
869 ext4_grpblk_t colour;
870 int flex_size = ext4_flex_bg_size(EXT4_SB(inode->i_sb));
871 ext4_fsblk_t bg_start;
872 ext4_fsblk_t last_block;
873
874 block_group = ei->i_block_group;
875 if (flex_size >= EXT4_FLEX_SIZE_DIR_ALLOC_SCHEME) {
876 /*
877 * If there are at least EXT4_FLEX_SIZE_DIR_ALLOC_SCHEME
878 * block groups per flexgroup, reserve the first block
879 * group for directories and special files. Regular
880 * files will start at the second block group. This
881 * tends to speed up directory access and improves
882 * fsck times.
883 */
884 block_group &= ~(flex_size-1);
885 if (S_ISREG(inode->i_mode))
886 block_group++;
887 }
888 bg_start = ext4_group_first_block_no(inode->i_sb, block_group);
889 last_block = ext4_blocks_count(EXT4_SB(inode->i_sb)->s_es) - 1;
890
891 /*
892 * If we are doing delayed allocation, we don't need take
893 * colour into account.
894 */
895 if (test_opt(inode->i_sb, DELALLOC))
896 return bg_start;
897
898 if (bg_start + EXT4_BLOCKS_PER_GROUP(inode->i_sb) <= last_block)
899 colour = (current->pid % 16) *
900 (EXT4_BLOCKS_PER_GROUP(inode->i_sb) / 16);
901 else
902 colour = (current->pid % 16) * ((last_block - bg_start) / 16);
903 return bg_start + colour;
904}
905