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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
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 the block group number and offset into the block/cluster
34 * allocation bitmap, given a block number
35 */
36void ext4_get_group_no_and_offset(struct super_block *sb, ext4_fsblk_t blocknr,
37 ext4_group_t *blockgrpp, ext4_grpblk_t *offsetp)
38{
39 struct ext4_super_block *es = EXT4_SB(sb)->s_es;
40 ext4_grpblk_t offset;
41
42 blocknr = blocknr - le32_to_cpu(es->s_first_data_block);
43 offset = do_div(blocknr, EXT4_BLOCKS_PER_GROUP(sb)) >>
44 EXT4_SB(sb)->s_cluster_bits;
45 if (offsetp)
46 *offsetp = offset;
47 if (blockgrpp)
48 *blockgrpp = blocknr;
49
50}
51
52static int ext4_block_in_group(struct super_block *sb, ext4_fsblk_t block,
53 ext4_group_t block_group)
54{
55 ext4_group_t actual_group;
56 ext4_get_group_no_and_offset(sb, block, &actual_group, NULL);
57 if (actual_group == block_group)
58 return 1;
59 return 0;
60}
61
62/* Return the number of clusters used for file system metadata; this
63 * represents the overhead needed by the file system.
64 */
65unsigned ext4_num_overhead_clusters(struct super_block *sb,
66 ext4_group_t block_group,
67 struct ext4_group_desc *gdp)
68{
69 unsigned num_clusters;
70 int block_cluster = -1, inode_cluster = -1, itbl_cluster = -1, i, c;
71 ext4_fsblk_t start = ext4_group_first_block_no(sb, block_group);
72 ext4_fsblk_t itbl_blk;
73 struct ext4_sb_info *sbi = EXT4_SB(sb);
74
75 /* This is the number of clusters used by the superblock,
76 * block group descriptors, and reserved block group
77 * descriptor blocks */
78 num_clusters = ext4_num_base_meta_clusters(sb, block_group);
79
80 /*
81 * For the allocation bitmaps and inode table, we first need
82 * to check to see if the block is in the block group. If it
83 * is, then check to see if the cluster is already accounted
84 * for in the clusters used for the base metadata cluster, or
85 * if we can increment the base metadata cluster to include
86 * that block. Otherwise, we will have to track the cluster
87 * used for the allocation bitmap or inode table explicitly.
88 * Normally all of these blocks are contiguous, so the special
89 * case handling shouldn't be necessary except for *very*
90 * unusual file system layouts.
91 */
92 if (ext4_block_in_group(sb, ext4_block_bitmap(sb, gdp), block_group)) {
93 block_cluster = EXT4_B2C(sbi,
94 ext4_block_bitmap(sb, gdp) - start);
95 if (block_cluster < num_clusters)
96 block_cluster = -1;
97 else if (block_cluster == num_clusters) {
98 num_clusters++;
99 block_cluster = -1;
100 }
101 }
102
103 if (ext4_block_in_group(sb, ext4_inode_bitmap(sb, gdp), block_group)) {
104 inode_cluster = EXT4_B2C(sbi,
105 ext4_inode_bitmap(sb, gdp) - start);
106 if (inode_cluster < num_clusters)
107 inode_cluster = -1;
108 else if (inode_cluster == num_clusters) {
109 num_clusters++;
110 inode_cluster = -1;
111 }
112 }
113
114 itbl_blk = ext4_inode_table(sb, gdp);
115 for (i = 0; i < sbi->s_itb_per_group; i++) {
116 if (ext4_block_in_group(sb, itbl_blk + i, block_group)) {
117 c = EXT4_B2C(sbi, itbl_blk + i - start);
118 if ((c < num_clusters) || (c == inode_cluster) ||
119 (c == block_cluster) || (c == itbl_cluster))
120 continue;
121 if (c == num_clusters) {
122 num_clusters++;
123 continue;
124 }
125 num_clusters++;
126 itbl_cluster = c;
127 }
128 }
129
130 if (block_cluster != -1)
131 num_clusters++;
132 if (inode_cluster != -1)
133 num_clusters++;
134
135 return num_clusters;
136}
137
138static unsigned int num_clusters_in_group(struct super_block *sb,
139 ext4_group_t block_group)
140{
141 unsigned int blocks;
142
143 if (block_group == ext4_get_groups_count(sb) - 1) {
144 /*
145 * Even though mke2fs always initializes the first and
146 * last group, just in case some other tool was used,
147 * we need to make sure we calculate the right free
148 * blocks.
149 */
150 blocks = ext4_blocks_count(EXT4_SB(sb)->s_es) -
151 ext4_group_first_block_no(sb, block_group);
152 } else
153 blocks = EXT4_BLOCKS_PER_GROUP(sb);
154 return EXT4_NUM_B2C(EXT4_SB(sb), blocks);
155}
156
157/* Initializes an uninitialized block bitmap */
158void ext4_init_block_bitmap(struct super_block *sb, struct buffer_head *bh,
159 ext4_group_t block_group,
160 struct ext4_group_desc *gdp)
161{
162 unsigned int bit, bit_max;
163 struct ext4_sb_info *sbi = EXT4_SB(sb);
164 ext4_fsblk_t start, tmp;
165 int flex_bg = 0;
166
167 J_ASSERT_BH(bh, buffer_locked(bh));
168
169 /* If checksum is bad mark all blocks used to prevent allocation
170 * essentially implementing a per-group read-only flag. */
171 if (!ext4_group_desc_csum_verify(sb, block_group, gdp)) {
172 ext4_error(sb, "Checksum bad for group %u", block_group);
173 ext4_free_group_clusters_set(sb, gdp, 0);
174 ext4_free_inodes_set(sb, gdp, 0);
175 ext4_itable_unused_set(sb, gdp, 0);
176 memset(bh->b_data, 0xff, sb->s_blocksize);
177 ext4_block_bitmap_csum_set(sb, block_group, gdp, bh,
178 EXT4_BLOCKS_PER_GROUP(sb) / 8);
179 return;
180 }
181 memset(bh->b_data, 0, sb->s_blocksize);
182
183 bit_max = ext4_num_base_meta_clusters(sb, block_group);
184 for (bit = 0; bit < bit_max; bit++)
185 ext4_set_bit(bit, bh->b_data);
186
187 start = ext4_group_first_block_no(sb, block_group);
188
189 if (EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_FLEX_BG))
190 flex_bg = 1;
191
192 /* Set bits for block and inode bitmaps, and inode table */
193 tmp = ext4_block_bitmap(sb, gdp);
194 if (!flex_bg || ext4_block_in_group(sb, tmp, block_group))
195 ext4_set_bit(EXT4_B2C(sbi, tmp - start), bh->b_data);
196
197 tmp = ext4_inode_bitmap(sb, gdp);
198 if (!flex_bg || ext4_block_in_group(sb, tmp, block_group))
199 ext4_set_bit(EXT4_B2C(sbi, tmp - start), bh->b_data);
200
201 tmp = ext4_inode_table(sb, gdp);
202 for (; tmp < ext4_inode_table(sb, gdp) +
203 sbi->s_itb_per_group; tmp++) {
204 if (!flex_bg || ext4_block_in_group(sb, tmp, block_group))
205 ext4_set_bit(EXT4_B2C(sbi, tmp - start), bh->b_data);
206 }
207
208 /*
209 * Also if the number of blocks within the group is less than
210 * the blocksize * 8 ( which is the size of bitmap ), set rest
211 * of the block bitmap to 1
212 */
213 ext4_mark_bitmap_end(num_clusters_in_group(sb, block_group),
214 sb->s_blocksize * 8, bh->b_data);
215 ext4_block_bitmap_csum_set(sb, block_group, gdp, bh,
216 EXT4_BLOCKS_PER_GROUP(sb) / 8);
217 ext4_group_desc_csum_set(sb, block_group, gdp);
218}
219
220/* Return the number of free blocks in a block group. It is used when
221 * the block bitmap is uninitialized, so we can't just count the bits
222 * in the bitmap. */
223unsigned ext4_free_clusters_after_init(struct super_block *sb,
224 ext4_group_t block_group,
225 struct ext4_group_desc *gdp)
226{
227 return num_clusters_in_group(sb, block_group) -
228 ext4_num_overhead_clusters(sb, block_group, gdp);
229}
230
231/*
232 * The free blocks are managed by bitmaps. A file system contains several
233 * blocks groups. Each group contains 1 bitmap block for blocks, 1 bitmap
234 * block for inodes, N blocks for the inode table and data blocks.
235 *
236 * The file system contains group descriptors which are located after the
237 * super block. Each descriptor contains the number of the bitmap block and
238 * the free blocks count in the block. The descriptors are loaded in memory
239 * when a file system is mounted (see ext4_fill_super).
240 */
241
242/**
243 * ext4_get_group_desc() -- load group descriptor from disk
244 * @sb: super block
245 * @block_group: given block group
246 * @bh: pointer to the buffer head to store the block
247 * group descriptor
248 */
249struct ext4_group_desc * ext4_get_group_desc(struct super_block *sb,
250 ext4_group_t block_group,
251 struct buffer_head **bh)
252{
253 unsigned int group_desc;
254 unsigned int offset;
255 ext4_group_t ngroups = ext4_get_groups_count(sb);
256 struct ext4_group_desc *desc;
257 struct ext4_sb_info *sbi = EXT4_SB(sb);
258
259 if (block_group >= ngroups) {
260 ext4_error(sb, "block_group >= groups_count - block_group = %u,"
261 " groups_count = %u", block_group, ngroups);
262
263 return NULL;
264 }
265
266 group_desc = block_group >> EXT4_DESC_PER_BLOCK_BITS(sb);
267 offset = block_group & (EXT4_DESC_PER_BLOCK(sb) - 1);
268 if (!sbi->s_group_desc[group_desc]) {
269 ext4_error(sb, "Group descriptor not loaded - "
270 "block_group = %u, group_desc = %u, desc = %u",
271 block_group, group_desc, offset);
272 return NULL;
273 }
274
275 desc = (struct ext4_group_desc *)(
276 (__u8 *)sbi->s_group_desc[group_desc]->b_data +
277 offset * EXT4_DESC_SIZE(sb));
278 if (bh)
279 *bh = sbi->s_group_desc[group_desc];
280 return desc;
281}
282
283/*
284 * Return the block number which was discovered to be invalid, or 0 if
285 * the block bitmap is valid.
286 */
287static ext4_fsblk_t ext4_valid_block_bitmap(struct super_block *sb,
288 struct ext4_group_desc *desc,
289 unsigned int block_group,
290 struct buffer_head *bh)
291{
292 ext4_grpblk_t offset;
293 ext4_grpblk_t next_zero_bit;
294 ext4_fsblk_t blk;
295 ext4_fsblk_t group_first_block;
296
297 if (EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_FLEX_BG)) {
298 /* with FLEX_BG, the inode/block bitmaps and itable
299 * blocks may not be in the group at all
300 * so the bitmap validation will be skipped for those groups
301 * or it has to also read the block group where the bitmaps
302 * are located to verify they are set.
303 */
304 return 0;
305 }
306 group_first_block = ext4_group_first_block_no(sb, block_group);
307
308 /* check whether block bitmap block number is set */
309 blk = ext4_block_bitmap(sb, desc);
310 offset = blk - group_first_block;
311 if (!ext4_test_bit(offset, bh->b_data))
312 /* bad block bitmap */
313 return blk;
314
315 /* check whether the inode bitmap block number is set */
316 blk = ext4_inode_bitmap(sb, desc);
317 offset = blk - group_first_block;
318 if (!ext4_test_bit(offset, bh->b_data))
319 /* bad block bitmap */
320 return blk;
321
322 /* check whether the inode table block number is set */
323 blk = ext4_inode_table(sb, desc);
324 offset = blk - group_first_block;
325 next_zero_bit = ext4_find_next_zero_bit(bh->b_data,
326 offset + EXT4_SB(sb)->s_itb_per_group,
327 offset);
328 if (next_zero_bit < offset + EXT4_SB(sb)->s_itb_per_group)
329 /* bad bitmap for inode tables */
330 return blk;
331 return 0;
332}
333
334void ext4_validate_block_bitmap(struct super_block *sb,
335 struct ext4_group_desc *desc,
336 unsigned int block_group,
337 struct buffer_head *bh)
338{
339 ext4_fsblk_t blk;
340
341 if (buffer_verified(bh))
342 return;
343
344 ext4_lock_group(sb, block_group);
345 blk = ext4_valid_block_bitmap(sb, desc, block_group, bh);
346 if (unlikely(blk != 0)) {
347 ext4_unlock_group(sb, block_group);
348 ext4_error(sb, "bg %u: block %llu: invalid block bitmap",
349 block_group, blk);
350 return;
351 }
352 if (unlikely(!ext4_block_bitmap_csum_verify(sb, block_group,
353 desc, bh, EXT4_BLOCKS_PER_GROUP(sb) / 8))) {
354 ext4_unlock_group(sb, block_group);
355 ext4_error(sb, "bg %u: bad block bitmap checksum", block_group);
356 return;
357 }
358 set_buffer_verified(bh);
359 ext4_unlock_group(sb, block_group);
360}
361
362/**
363 * ext4_read_block_bitmap()
364 * @sb: super block
365 * @block_group: given block group
366 *
367 * Read the bitmap for a given block_group,and validate the
368 * bits for block/inode/inode tables are set in the bitmaps
369 *
370 * Return buffer_head on success or NULL in case of failure.
371 */
372struct buffer_head *
373ext4_read_block_bitmap_nowait(struct super_block *sb, ext4_group_t block_group)
374{
375 struct ext4_group_desc *desc;
376 struct buffer_head *bh;
377 ext4_fsblk_t bitmap_blk;
378
379 desc = ext4_get_group_desc(sb, block_group, NULL);
380 if (!desc)
381 return NULL;
382 bitmap_blk = ext4_block_bitmap(sb, desc);
383 bh = sb_getblk(sb, bitmap_blk);
384 if (unlikely(!bh)) {
385 ext4_error(sb, "Cannot get buffer for block bitmap - "
386 "block_group = %u, block_bitmap = %llu",
387 block_group, bitmap_blk);
388 return NULL;
389 }
390
391 if (bitmap_uptodate(bh))
392 goto verify;
393
394 lock_buffer(bh);
395 if (bitmap_uptodate(bh)) {
396 unlock_buffer(bh);
397 goto verify;
398 }
399 ext4_lock_group(sb, block_group);
400 if (desc->bg_flags & cpu_to_le16(EXT4_BG_BLOCK_UNINIT)) {
401 ext4_init_block_bitmap(sb, bh, block_group, desc);
402 set_bitmap_uptodate(bh);
403 set_buffer_uptodate(bh);
404 ext4_unlock_group(sb, block_group);
405 unlock_buffer(bh);
406 return bh;
407 }
408 ext4_unlock_group(sb, block_group);
409 if (buffer_uptodate(bh)) {
410 /*
411 * if not uninit if bh is uptodate,
412 * bitmap is also uptodate
413 */
414 set_bitmap_uptodate(bh);
415 unlock_buffer(bh);
416 goto verify;
417 }
418 /*
419 * submit the buffer_head for reading
420 */
421 set_buffer_new(bh);
422 trace_ext4_read_block_bitmap_load(sb, block_group);
423 bh->b_end_io = ext4_end_bitmap_read;
424 get_bh(bh);
425 submit_bh(READ, bh);
426 return bh;
427verify:
428 ext4_validate_block_bitmap(sb, desc, block_group, bh);
429 return bh;
430}
431
432/* Returns 0 on success, 1 on error */
433int ext4_wait_block_bitmap(struct super_block *sb, ext4_group_t block_group,
434 struct buffer_head *bh)
435{
436 struct ext4_group_desc *desc;
437
438 if (!buffer_new(bh))
439 return 0;
440 desc = ext4_get_group_desc(sb, block_group, NULL);
441 if (!desc)
442 return 1;
443 wait_on_buffer(bh);
444 if (!buffer_uptodate(bh)) {
445 ext4_error(sb, "Cannot read block bitmap - "
446 "block_group = %u, block_bitmap = %llu",
447 block_group, (unsigned long long) bh->b_blocknr);
448 return 1;
449 }
450 clear_buffer_new(bh);
451 /* Panic or remount fs read-only if block bitmap is invalid */
452 ext4_validate_block_bitmap(sb, desc, block_group, bh);
453 return 0;
454}
455
456struct buffer_head *
457ext4_read_block_bitmap(struct super_block *sb, ext4_group_t block_group)
458{
459 struct buffer_head *bh;
460
461 bh = ext4_read_block_bitmap_nowait(sb, block_group);
462 if (ext4_wait_block_bitmap(sb, block_group, bh)) {
463 put_bh(bh);
464 return NULL;
465 }
466 return bh;
467}
468
469/**
470 * ext4_has_free_clusters()
471 * @sbi: in-core super block structure.
472 * @nclusters: number of needed blocks
473 * @flags: flags from ext4_mb_new_blocks()
474 *
475 * Check if filesystem has nclusters free & available for allocation.
476 * On success return 1, return 0 on failure.
477 */
478static int ext4_has_free_clusters(struct ext4_sb_info *sbi,
479 s64 nclusters, unsigned int flags)
480{
481 s64 free_clusters, dirty_clusters, root_clusters;
482 struct percpu_counter *fcc = &sbi->s_freeclusters_counter;
483 struct percpu_counter *dcc = &sbi->s_dirtyclusters_counter;
484
485 free_clusters = percpu_counter_read_positive(fcc);
486 dirty_clusters = percpu_counter_read_positive(dcc);
487 root_clusters = EXT4_B2C(sbi, ext4_r_blocks_count(sbi->s_es));
488
489 if (free_clusters - (nclusters + root_clusters + dirty_clusters) <
490 EXT4_FREECLUSTERS_WATERMARK) {
491 free_clusters = EXT4_C2B(sbi, percpu_counter_sum_positive(fcc));
492 dirty_clusters = percpu_counter_sum_positive(dcc);
493 }
494 /* Check whether we have space after accounting for current
495 * dirty clusters & root reserved clusters.
496 */
497 if (free_clusters >= ((root_clusters + nclusters) + dirty_clusters))
498 return 1;
499
500 /* Hm, nope. Are (enough) root reserved clusters available? */
501 if (uid_eq(sbi->s_resuid, current_fsuid()) ||
502 (!gid_eq(sbi->s_resgid, GLOBAL_ROOT_GID) && in_group_p(sbi->s_resgid)) ||
503 capable(CAP_SYS_RESOURCE) ||
504 (flags & EXT4_MB_USE_ROOT_BLOCKS)) {
505
506 if (free_clusters >= (nclusters + dirty_clusters))
507 return 1;
508 }
509
510 return 0;
511}
512
513int ext4_claim_free_clusters(struct ext4_sb_info *sbi,
514 s64 nclusters, unsigned int flags)
515{
516 if (ext4_has_free_clusters(sbi, nclusters, flags)) {
517 percpu_counter_add(&sbi->s_dirtyclusters_counter, nclusters);
518 return 0;
519 } else
520 return -ENOSPC;
521}
522
523/**
524 * ext4_should_retry_alloc()
525 * @sb: super block
526 * @retries number of attemps has been made
527 *
528 * ext4_should_retry_alloc() is called when ENOSPC is returned, and if
529 * it is profitable to retry the operation, this function will wait
530 * for the current or committing transaction to complete, and then
531 * return TRUE.
532 *
533 * if the total number of retries exceed three times, return FALSE.
534 */
535int ext4_should_retry_alloc(struct super_block *sb, int *retries)
536{
537 if (!ext4_has_free_clusters(EXT4_SB(sb), 1, 0) ||
538 (*retries)++ > 3 ||
539 !EXT4_SB(sb)->s_journal)
540 return 0;
541
542 jbd_debug(1, "%s: retrying operation after ENOSPC\n", sb->s_id);
543
544 return jbd2_journal_force_commit_nested(EXT4_SB(sb)->s_journal);
545}
546
547/*
548 * ext4_new_meta_blocks() -- allocate block for meta data (indexing) blocks
549 *
550 * @handle: handle to this transaction
551 * @inode: file inode
552 * @goal: given target block(filesystem wide)
553 * @count: pointer to total number of clusters needed
554 * @errp: error code
555 *
556 * Return 1st allocated block number on success, *count stores total account
557 * error stores in errp pointer
558 */
559ext4_fsblk_t ext4_new_meta_blocks(handle_t *handle, struct inode *inode,
560 ext4_fsblk_t goal, unsigned int flags,
561 unsigned long *count, int *errp)
562{
563 struct ext4_allocation_request ar;
564 ext4_fsblk_t ret;
565
566 memset(&ar, 0, sizeof(ar));
567 /* Fill with neighbour allocated blocks */
568 ar.inode = inode;
569 ar.goal = goal;
570 ar.len = count ? *count : 1;
571 ar.flags = flags;
572
573 ret = ext4_mb_new_blocks(handle, &ar, errp);
574 if (count)
575 *count = ar.len;
576 /*
577 * Account for the allocated meta blocks. We will never
578 * fail EDQUOT for metdata, but we do account for it.
579 */
580 if (!(*errp) &&
581 ext4_test_inode_state(inode, EXT4_STATE_DELALLOC_RESERVED)) {
582 spin_lock(&EXT4_I(inode)->i_block_reservation_lock);
583 EXT4_I(inode)->i_allocated_meta_blocks += ar.len;
584 spin_unlock(&EXT4_I(inode)->i_block_reservation_lock);
585 dquot_alloc_block_nofail(inode,
586 EXT4_C2B(EXT4_SB(inode->i_sb), ar.len));
587 }
588 return ret;
589}
590
591/**
592 * ext4_count_free_clusters() -- count filesystem free clusters
593 * @sb: superblock
594 *
595 * Adds up the number of free clusters from each block group.
596 */
597ext4_fsblk_t ext4_count_free_clusters(struct super_block *sb)
598{
599 ext4_fsblk_t desc_count;
600 struct ext4_group_desc *gdp;
601 ext4_group_t i;
602 ext4_group_t ngroups = ext4_get_groups_count(sb);
603#ifdef EXT4FS_DEBUG
604 struct ext4_super_block *es;
605 ext4_fsblk_t bitmap_count;
606 unsigned int x;
607 struct buffer_head *bitmap_bh = NULL;
608
609 es = EXT4_SB(sb)->s_es;
610 desc_count = 0;
611 bitmap_count = 0;
612 gdp = NULL;
613
614 for (i = 0; i < ngroups; i++) {
615 gdp = ext4_get_group_desc(sb, i, NULL);
616 if (!gdp)
617 continue;
618 desc_count += ext4_free_group_clusters(sb, gdp);
619 brelse(bitmap_bh);
620 bitmap_bh = ext4_read_block_bitmap(sb, i);
621 if (bitmap_bh == NULL)
622 continue;
623
624 x = ext4_count_free(bitmap_bh->b_data,
625 EXT4_BLOCKS_PER_GROUP(sb) / 8);
626 printk(KERN_DEBUG "group %u: stored = %d, counted = %u\n",
627 i, ext4_free_group_clusters(sb, gdp), x);
628 bitmap_count += x;
629 }
630 brelse(bitmap_bh);
631 printk(KERN_DEBUG "ext4_count_free_clusters: stored = %llu"
632 ", computed = %llu, %llu\n",
633 EXT4_B2C(EXT4_SB(sb), ext4_free_blocks_count(es)),
634 desc_count, bitmap_count);
635 return bitmap_count;
636#else
637 desc_count = 0;
638 for (i = 0; i < ngroups; i++) {
639 gdp = ext4_get_group_desc(sb, i, NULL);
640 if (!gdp)
641 continue;
642 desc_count += ext4_free_group_clusters(sb, gdp);
643 }
644
645 return desc_count;
646#endif
647}
648
649static inline int test_root(ext4_group_t a, int b)
650{
651 int num = b;
652
653 while (a > num)
654 num *= b;
655 return num == a;
656}
657
658static int ext4_group_sparse(ext4_group_t group)
659{
660 if (group <= 1)
661 return 1;
662 if (!(group & 1))
663 return 0;
664 return (test_root(group, 7) || test_root(group, 5) ||
665 test_root(group, 3));
666}
667
668/**
669 * ext4_bg_has_super - number of blocks used by the superblock in group
670 * @sb: superblock for filesystem
671 * @group: group number to check
672 *
673 * Return the number of blocks used by the superblock (primary or backup)
674 * in this group. Currently this will be only 0 or 1.
675 */
676int ext4_bg_has_super(struct super_block *sb, ext4_group_t group)
677{
678 if (EXT4_HAS_RO_COMPAT_FEATURE(sb,
679 EXT4_FEATURE_RO_COMPAT_SPARSE_SUPER) &&
680 !ext4_group_sparse(group))
681 return 0;
682 return 1;
683}
684
685static unsigned long ext4_bg_num_gdb_meta(struct super_block *sb,
686 ext4_group_t group)
687{
688 unsigned long metagroup = group / EXT4_DESC_PER_BLOCK(sb);
689 ext4_group_t first = metagroup * EXT4_DESC_PER_BLOCK(sb);
690 ext4_group_t last = first + EXT4_DESC_PER_BLOCK(sb) - 1;
691
692 if (group == first || group == first + 1 || group == last)
693 return 1;
694 return 0;
695}
696
697static unsigned long ext4_bg_num_gdb_nometa(struct super_block *sb,
698 ext4_group_t group)
699{
700 if (!ext4_bg_has_super(sb, group))
701 return 0;
702
703 if (EXT4_HAS_INCOMPAT_FEATURE(sb,EXT4_FEATURE_INCOMPAT_META_BG))
704 return le32_to_cpu(EXT4_SB(sb)->s_es->s_first_meta_bg);
705 else
706 return EXT4_SB(sb)->s_gdb_count;
707}
708
709/**
710 * ext4_bg_num_gdb - number of blocks used by the group table in group
711 * @sb: superblock for filesystem
712 * @group: group number to check
713 *
714 * Return the number of blocks used by the group descriptor table
715 * (primary or backup) in this group. In the future there may be a
716 * different number of descriptor blocks in each group.
717 */
718unsigned long ext4_bg_num_gdb(struct super_block *sb, ext4_group_t group)
719{
720 unsigned long first_meta_bg =
721 le32_to_cpu(EXT4_SB(sb)->s_es->s_first_meta_bg);
722 unsigned long metagroup = group / EXT4_DESC_PER_BLOCK(sb);
723
724 if (!EXT4_HAS_INCOMPAT_FEATURE(sb,EXT4_FEATURE_INCOMPAT_META_BG) ||
725 metagroup < first_meta_bg)
726 return ext4_bg_num_gdb_nometa(sb, group);
727
728 return ext4_bg_num_gdb_meta(sb,group);
729
730}
731
732/*
733 * This function returns the number of file system metadata clusters at
734 * the beginning of a block group, including the reserved gdt blocks.
735 */
736static unsigned ext4_num_base_meta_clusters(struct super_block *sb,
737 ext4_group_t block_group)
738{
739 struct ext4_sb_info *sbi = EXT4_SB(sb);
740 unsigned num;
741
742 /* Check for superblock and gdt backups in this group */
743 num = ext4_bg_has_super(sb, block_group);
744
745 if (!EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_META_BG) ||
746 block_group < le32_to_cpu(sbi->s_es->s_first_meta_bg) *
747 sbi->s_desc_per_block) {
748 if (num) {
749 num += ext4_bg_num_gdb(sb, block_group);
750 num += le16_to_cpu(sbi->s_es->s_reserved_gdt_blocks);
751 }
752 } else { /* For META_BG_BLOCK_GROUPS */
753 num += ext4_bg_num_gdb(sb, block_group);
754 }
755 return EXT4_NUM_B2C(sbi, num);
756}
757/**
758 * ext4_inode_to_goal_block - return a hint for block allocation
759 * @inode: inode for block allocation
760 *
761 * Return the ideal location to start allocating blocks for a
762 * newly created inode.
763 */
764ext4_fsblk_t ext4_inode_to_goal_block(struct inode *inode)
765{
766 struct ext4_inode_info *ei = EXT4_I(inode);
767 ext4_group_t block_group;
768 ext4_grpblk_t colour;
769 int flex_size = ext4_flex_bg_size(EXT4_SB(inode->i_sb));
770 ext4_fsblk_t bg_start;
771 ext4_fsblk_t last_block;
772
773 block_group = ei->i_block_group;
774 if (flex_size >= EXT4_FLEX_SIZE_DIR_ALLOC_SCHEME) {
775 /*
776 * If there are at least EXT4_FLEX_SIZE_DIR_ALLOC_SCHEME
777 * block groups per flexgroup, reserve the first block
778 * group for directories and special files. Regular
779 * files will start at the second block group. This
780 * tends to speed up directory access and improves
781 * fsck times.
782 */
783 block_group &= ~(flex_size-1);
784 if (S_ISREG(inode->i_mode))
785 block_group++;
786 }
787 bg_start = ext4_group_first_block_no(inode->i_sb, block_group);
788 last_block = ext4_blocks_count(EXT4_SB(inode->i_sb)->s_es) - 1;
789
790 /*
791 * If we are doing delayed allocation, we don't need take
792 * colour into account.
793 */
794 if (test_opt(inode->i_sb, DELALLOC))
795 return bg_start;
796
797 if (bg_start + EXT4_BLOCKS_PER_GROUP(inode->i_sb) <= last_block)
798 colour = (current->pid % 16) *
799 (EXT4_BLOCKS_PER_GROUP(inode->i_sb) / 16);
800 else
801 colour = (current->pid % 16) * ((last_block - bg_start) / 16);
802 return bg_start + colour;
803}
804
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
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_mark_group_bitmap_corrupted(sb, block_group,
194 EXT4_GROUP_INFO_BBITMAP_CORRUPT |
195 EXT4_GROUP_INFO_IBITMAP_CORRUPT);
196 return -EFSBADCRC;
197 }
198 memset(bh->b_data, 0, sb->s_blocksize);
199
200 bit_max = ext4_num_base_meta_clusters(sb, block_group);
201 if ((bit_max >> 3) >= bh->b_size)
202 return -EFSCORRUPTED;
203
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 /* Set bits for block and inode bitmaps, and inode table */
210 tmp = ext4_block_bitmap(sb, gdp);
211 if (ext4_block_in_group(sb, tmp, block_group))
212 ext4_set_bit(EXT4_B2C(sbi, tmp - start), bh->b_data);
213
214 tmp = ext4_inode_bitmap(sb, gdp);
215 if (ext4_block_in_group(sb, tmp, block_group))
216 ext4_set_bit(EXT4_B2C(sbi, tmp - start), bh->b_data);
217
218 tmp = ext4_inode_table(sb, gdp);
219 for (; tmp < ext4_inode_table(sb, gdp) +
220 sbi->s_itb_per_group; tmp++) {
221 if (ext4_block_in_group(sb, tmp, block_group))
222 ext4_set_bit(EXT4_B2C(sbi, tmp - start), bh->b_data);
223 }
224
225 /*
226 * Also if the number of blocks within the group is less than
227 * the blocksize * 8 ( which is the size of bitmap ), set rest
228 * of the block bitmap to 1
229 */
230 ext4_mark_bitmap_end(num_clusters_in_group(sb, block_group),
231 sb->s_blocksize * 8, bh->b_data);
232 return 0;
233}
234
235/* Return the number of free blocks in a block group. It is used when
236 * the block bitmap is uninitialized, so we can't just count the bits
237 * in the bitmap. */
238unsigned ext4_free_clusters_after_init(struct super_block *sb,
239 ext4_group_t block_group,
240 struct ext4_group_desc *gdp)
241{
242 return num_clusters_in_group(sb, block_group) -
243 ext4_num_overhead_clusters(sb, block_group, gdp);
244}
245
246/*
247 * The free blocks are managed by bitmaps. A file system contains several
248 * blocks groups. Each group contains 1 bitmap block for blocks, 1 bitmap
249 * block for inodes, N blocks for the inode table and data blocks.
250 *
251 * The file system contains group descriptors which are located after the
252 * super block. Each descriptor contains the number of the bitmap block and
253 * the free blocks count in the block. The descriptors are loaded in memory
254 * when a file system is mounted (see ext4_fill_super).
255 */
256
257/**
258 * ext4_get_group_desc() -- load group descriptor from disk
259 * @sb: super block
260 * @block_group: given block group
261 * @bh: pointer to the buffer head to store the block
262 * group descriptor
263 */
264struct ext4_group_desc * ext4_get_group_desc(struct super_block *sb,
265 ext4_group_t block_group,
266 struct buffer_head **bh)
267{
268 unsigned int group_desc;
269 unsigned int offset;
270 ext4_group_t ngroups = ext4_get_groups_count(sb);
271 struct ext4_group_desc *desc;
272 struct ext4_sb_info *sbi = EXT4_SB(sb);
273
274 if (block_group >= ngroups) {
275 ext4_error(sb, "block_group >= groups_count - block_group = %u,"
276 " groups_count = %u", block_group, ngroups);
277
278 return NULL;
279 }
280
281 group_desc = block_group >> EXT4_DESC_PER_BLOCK_BITS(sb);
282 offset = block_group & (EXT4_DESC_PER_BLOCK(sb) - 1);
283 if (!sbi->s_group_desc[group_desc]) {
284 ext4_error(sb, "Group descriptor not loaded - "
285 "block_group = %u, group_desc = %u, desc = %u",
286 block_group, group_desc, offset);
287 return NULL;
288 }
289
290 desc = (struct ext4_group_desc *)(
291 (__u8 *)sbi->s_group_desc[group_desc]->b_data +
292 offset * EXT4_DESC_SIZE(sb));
293 if (bh)
294 *bh = sbi->s_group_desc[group_desc];
295 return desc;
296}
297
298/*
299 * Return the block number which was discovered to be invalid, or 0 if
300 * the block bitmap is valid.
301 */
302static ext4_fsblk_t ext4_valid_block_bitmap(struct super_block *sb,
303 struct ext4_group_desc *desc,
304 ext4_group_t block_group,
305 struct buffer_head *bh)
306{
307 struct ext4_sb_info *sbi = EXT4_SB(sb);
308 ext4_grpblk_t offset;
309 ext4_grpblk_t next_zero_bit;
310 ext4_grpblk_t max_bit = EXT4_CLUSTERS_PER_GROUP(sb);
311 ext4_fsblk_t blk;
312 ext4_fsblk_t group_first_block;
313
314 if (ext4_has_feature_flex_bg(sb)) {
315 /* with FLEX_BG, the inode/block bitmaps and itable
316 * blocks may not be in the group at all
317 * so the bitmap validation will be skipped for those groups
318 * or it has to also read the block group where the bitmaps
319 * are located to verify they are set.
320 */
321 return 0;
322 }
323 group_first_block = ext4_group_first_block_no(sb, block_group);
324
325 /* check whether block bitmap block number is set */
326 blk = ext4_block_bitmap(sb, desc);
327 offset = blk - group_first_block;
328 if (offset < 0 || EXT4_B2C(sbi, offset) >= max_bit ||
329 !ext4_test_bit(EXT4_B2C(sbi, offset), bh->b_data))
330 /* bad block bitmap */
331 return blk;
332
333 /* check whether the inode bitmap block number is set */
334 blk = ext4_inode_bitmap(sb, desc);
335 offset = blk - group_first_block;
336 if (offset < 0 || EXT4_B2C(sbi, offset) >= max_bit ||
337 !ext4_test_bit(EXT4_B2C(sbi, 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 if (offset < 0 || EXT4_B2C(sbi, offset) >= max_bit ||
345 EXT4_B2C(sbi, offset + sbi->s_itb_per_group) >= max_bit)
346 return blk;
347 next_zero_bit = ext4_find_next_zero_bit(bh->b_data,
348 EXT4_B2C(sbi, offset + sbi->s_itb_per_group),
349 EXT4_B2C(sbi, offset));
350 if (next_zero_bit <
351 EXT4_B2C(sbi, offset + sbi->s_itb_per_group))
352 /* bad bitmap for inode tables */
353 return blk;
354 return 0;
355}
356
357static int ext4_validate_block_bitmap(struct super_block *sb,
358 struct ext4_group_desc *desc,
359 ext4_group_t block_group,
360 struct buffer_head *bh)
361{
362 ext4_fsblk_t blk;
363 struct ext4_group_info *grp = ext4_get_group_info(sb, block_group);
364
365 if (buffer_verified(bh))
366 return 0;
367 if (EXT4_MB_GRP_BBITMAP_CORRUPT(grp))
368 return -EFSCORRUPTED;
369
370 ext4_lock_group(sb, block_group);
371 if (buffer_verified(bh))
372 goto verified;
373 if (unlikely(!ext4_block_bitmap_csum_verify(sb, block_group,
374 desc, bh))) {
375 ext4_unlock_group(sb, block_group);
376 ext4_error(sb, "bg %u: bad block bitmap checksum", block_group);
377 ext4_mark_group_bitmap_corrupted(sb, block_group,
378 EXT4_GROUP_INFO_BBITMAP_CORRUPT);
379 return -EFSBADCRC;
380 }
381 blk = ext4_valid_block_bitmap(sb, desc, block_group, bh);
382 if (unlikely(blk != 0)) {
383 ext4_unlock_group(sb, block_group);
384 ext4_error(sb, "bg %u: block %llu: invalid block bitmap",
385 block_group, blk);
386 ext4_mark_group_bitmap_corrupted(sb, block_group,
387 EXT4_GROUP_INFO_BBITMAP_CORRUPT);
388 return -EFSCORRUPTED;
389 }
390 set_buffer_verified(bh);
391verified:
392 ext4_unlock_group(sb, block_group);
393 return 0;
394}
395
396/**
397 * ext4_read_block_bitmap_nowait()
398 * @sb: super block
399 * @block_group: given block group
400 *
401 * Read the bitmap for a given block_group,and validate the
402 * bits for block/inode/inode tables are set in the bitmaps
403 *
404 * Return buffer_head on success or NULL in case of failure.
405 */
406struct buffer_head *
407ext4_read_block_bitmap_nowait(struct super_block *sb, ext4_group_t block_group)
408{
409 struct ext4_group_desc *desc;
410 struct ext4_sb_info *sbi = EXT4_SB(sb);
411 struct buffer_head *bh;
412 ext4_fsblk_t bitmap_blk;
413 int err;
414
415 desc = ext4_get_group_desc(sb, block_group, NULL);
416 if (!desc)
417 return ERR_PTR(-EFSCORRUPTED);
418 bitmap_blk = ext4_block_bitmap(sb, desc);
419 if ((bitmap_blk <= le32_to_cpu(sbi->s_es->s_first_data_block)) ||
420 (bitmap_blk >= ext4_blocks_count(sbi->s_es))) {
421 ext4_error(sb, "Invalid block bitmap block %llu in "
422 "block_group %u", bitmap_blk, block_group);
423 ext4_mark_group_bitmap_corrupted(sb, block_group,
424 EXT4_GROUP_INFO_BBITMAP_CORRUPT);
425 return ERR_PTR(-EFSCORRUPTED);
426 }
427 bh = sb_getblk(sb, bitmap_blk);
428 if (unlikely(!bh)) {
429 ext4_warning(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 (ext4_has_group_desc_csum(sb) &&
445 (desc->bg_flags & cpu_to_le16(EXT4_BG_BLOCK_UNINIT))) {
446 if (block_group == 0) {
447 ext4_unlock_group(sb, block_group);
448 unlock_buffer(bh);
449 ext4_error(sb, "Block bitmap for bg 0 marked "
450 "uninitialized");
451 err = -EFSCORRUPTED;
452 goto out;
453 }
454 err = ext4_init_block_bitmap(sb, bh, block_group, desc);
455 set_bitmap_uptodate(bh);
456 set_buffer_uptodate(bh);
457 set_buffer_verified(bh);
458 ext4_unlock_group(sb, block_group);
459 unlock_buffer(bh);
460 if (err) {
461 ext4_error(sb, "Failed to init block bitmap for group "
462 "%u: %d", block_group, err);
463 goto out;
464 }
465 goto verify;
466 }
467 ext4_unlock_group(sb, block_group);
468 if (buffer_uptodate(bh)) {
469 /*
470 * if not uninit if bh is uptodate,
471 * bitmap is also uptodate
472 */
473 set_bitmap_uptodate(bh);
474 unlock_buffer(bh);
475 goto verify;
476 }
477 /*
478 * submit the buffer_head for reading
479 */
480 set_buffer_new(bh);
481 trace_ext4_read_block_bitmap_load(sb, block_group);
482 bh->b_end_io = ext4_end_bitmap_read;
483 get_bh(bh);
484 submit_bh(REQ_OP_READ, REQ_META | REQ_PRIO, bh);
485 return bh;
486verify:
487 err = ext4_validate_block_bitmap(sb, desc, block_group, bh);
488 if (err)
489 goto out;
490 return bh;
491out:
492 put_bh(bh);
493 return ERR_PTR(err);
494}
495
496/* Returns 0 on success, 1 on error */
497int ext4_wait_block_bitmap(struct super_block *sb, ext4_group_t block_group,
498 struct buffer_head *bh)
499{
500 struct ext4_group_desc *desc;
501
502 if (!buffer_new(bh))
503 return 0;
504 desc = ext4_get_group_desc(sb, block_group, NULL);
505 if (!desc)
506 return -EFSCORRUPTED;
507 wait_on_buffer(bh);
508 if (!buffer_uptodate(bh)) {
509 ext4_error(sb, "Cannot read block bitmap - "
510 "block_group = %u, block_bitmap = %llu",
511 block_group, (unsigned long long) bh->b_blocknr);
512 ext4_mark_group_bitmap_corrupted(sb, block_group,
513 EXT4_GROUP_INFO_BBITMAP_CORRUPT);
514 return -EIO;
515 }
516 clear_buffer_new(bh);
517 /* Panic or remount fs read-only if block bitmap is invalid */
518 return ext4_validate_block_bitmap(sb, desc, block_group, bh);
519}
520
521struct buffer_head *
522ext4_read_block_bitmap(struct super_block *sb, ext4_group_t block_group)
523{
524 struct buffer_head *bh;
525 int err;
526
527 bh = ext4_read_block_bitmap_nowait(sb, block_group);
528 if (IS_ERR(bh))
529 return bh;
530 err = ext4_wait_block_bitmap(sb, block_group, bh);
531 if (err) {
532 put_bh(bh);
533 return ERR_PTR(err);
534 }
535 return bh;
536}
537
538/**
539 * ext4_has_free_clusters()
540 * @sbi: in-core super block structure.
541 * @nclusters: number of needed blocks
542 * @flags: flags from ext4_mb_new_blocks()
543 *
544 * Check if filesystem has nclusters free & available for allocation.
545 * On success return 1, return 0 on failure.
546 */
547static int ext4_has_free_clusters(struct ext4_sb_info *sbi,
548 s64 nclusters, unsigned int flags)
549{
550 s64 free_clusters, dirty_clusters, rsv, resv_clusters;
551 struct percpu_counter *fcc = &sbi->s_freeclusters_counter;
552 struct percpu_counter *dcc = &sbi->s_dirtyclusters_counter;
553
554 free_clusters = percpu_counter_read_positive(fcc);
555 dirty_clusters = percpu_counter_read_positive(dcc);
556 resv_clusters = atomic64_read(&sbi->s_resv_clusters);
557
558 /*
559 * r_blocks_count should always be multiple of the cluster ratio so
560 * we are safe to do a plane bit shift only.
561 */
562 rsv = (ext4_r_blocks_count(sbi->s_es) >> sbi->s_cluster_bits) +
563 resv_clusters;
564
565 if (free_clusters - (nclusters + rsv + dirty_clusters) <
566 EXT4_FREECLUSTERS_WATERMARK) {
567 free_clusters = percpu_counter_sum_positive(fcc);
568 dirty_clusters = percpu_counter_sum_positive(dcc);
569 }
570 /* Check whether we have space after accounting for current
571 * dirty clusters & root reserved clusters.
572 */
573 if (free_clusters >= (rsv + nclusters + dirty_clusters))
574 return 1;
575
576 /* Hm, nope. Are (enough) root reserved clusters available? */
577 if (uid_eq(sbi->s_resuid, current_fsuid()) ||
578 (!gid_eq(sbi->s_resgid, GLOBAL_ROOT_GID) && in_group_p(sbi->s_resgid)) ||
579 capable(CAP_SYS_RESOURCE) ||
580 (flags & EXT4_MB_USE_ROOT_BLOCKS)) {
581
582 if (free_clusters >= (nclusters + dirty_clusters +
583 resv_clusters))
584 return 1;
585 }
586 /* No free blocks. Let's see if we can dip into reserved pool */
587 if (flags & EXT4_MB_USE_RESERVED) {
588 if (free_clusters >= (nclusters + dirty_clusters))
589 return 1;
590 }
591
592 return 0;
593}
594
595int ext4_claim_free_clusters(struct ext4_sb_info *sbi,
596 s64 nclusters, unsigned int flags)
597{
598 if (ext4_has_free_clusters(sbi, nclusters, flags)) {
599 percpu_counter_add(&sbi->s_dirtyclusters_counter, nclusters);
600 return 0;
601 } else
602 return -ENOSPC;
603}
604
605/**
606 * ext4_should_retry_alloc() - check if a block allocation should be retried
607 * @sb: super block
608 * @retries: number of attemps has been made
609 *
610 * ext4_should_retry_alloc() is called when ENOSPC is returned, and if
611 * it is profitable to retry the operation, this function will wait
612 * for the current or committing transaction to complete, and then
613 * return TRUE. We will only retry once.
614 */
615int ext4_should_retry_alloc(struct super_block *sb, int *retries)
616{
617 if (!ext4_has_free_clusters(EXT4_SB(sb), 1, 0) ||
618 (*retries)++ > 1 ||
619 !EXT4_SB(sb)->s_journal)
620 return 0;
621
622 smp_mb();
623 if (EXT4_SB(sb)->s_mb_free_pending == 0)
624 return 0;
625
626 jbd_debug(1, "%s: retrying operation after ENOSPC\n", sb->s_id);
627 jbd2_journal_force_commit_nested(EXT4_SB(sb)->s_journal);
628 return 1;
629}
630
631/*
632 * ext4_new_meta_blocks() -- allocate block for meta data (indexing) blocks
633 *
634 * @handle: handle to this transaction
635 * @inode: file inode
636 * @goal: given target block(filesystem wide)
637 * @count: pointer to total number of clusters needed
638 * @errp: error code
639 *
640 * Return 1st allocated block number on success, *count stores total account
641 * error stores in errp pointer
642 */
643ext4_fsblk_t ext4_new_meta_blocks(handle_t *handle, struct inode *inode,
644 ext4_fsblk_t goal, unsigned int flags,
645 unsigned long *count, int *errp)
646{
647 struct ext4_allocation_request ar;
648 ext4_fsblk_t ret;
649
650 memset(&ar, 0, sizeof(ar));
651 /* Fill with neighbour allocated blocks */
652 ar.inode = inode;
653 ar.goal = goal;
654 ar.len = count ? *count : 1;
655 ar.flags = flags;
656
657 ret = ext4_mb_new_blocks(handle, &ar, errp);
658 if (count)
659 *count = ar.len;
660 /*
661 * Account for the allocated meta blocks. We will never
662 * fail EDQUOT for metdata, but we do account for it.
663 */
664 if (!(*errp) && (flags & EXT4_MB_DELALLOC_RESERVED)) {
665 dquot_alloc_block_nofail(inode,
666 EXT4_C2B(EXT4_SB(inode->i_sb), ar.len));
667 }
668 return ret;
669}
670
671/**
672 * ext4_count_free_clusters() -- count filesystem free clusters
673 * @sb: superblock
674 *
675 * Adds up the number of free clusters from each block group.
676 */
677ext4_fsblk_t ext4_count_free_clusters(struct super_block *sb)
678{
679 ext4_fsblk_t desc_count;
680 struct ext4_group_desc *gdp;
681 ext4_group_t i;
682 ext4_group_t ngroups = ext4_get_groups_count(sb);
683 struct ext4_group_info *grp;
684#ifdef EXT4FS_DEBUG
685 struct ext4_super_block *es;
686 ext4_fsblk_t bitmap_count;
687 unsigned int x;
688 struct buffer_head *bitmap_bh = NULL;
689
690 es = EXT4_SB(sb)->s_es;
691 desc_count = 0;
692 bitmap_count = 0;
693 gdp = NULL;
694
695 for (i = 0; i < ngroups; i++) {
696 gdp = ext4_get_group_desc(sb, i, NULL);
697 if (!gdp)
698 continue;
699 grp = NULL;
700 if (EXT4_SB(sb)->s_group_info)
701 grp = ext4_get_group_info(sb, i);
702 if (!grp || !EXT4_MB_GRP_BBITMAP_CORRUPT(grp))
703 desc_count += ext4_free_group_clusters(sb, gdp);
704 brelse(bitmap_bh);
705 bitmap_bh = ext4_read_block_bitmap(sb, i);
706 if (IS_ERR(bitmap_bh)) {
707 bitmap_bh = NULL;
708 continue;
709 }
710
711 x = ext4_count_free(bitmap_bh->b_data,
712 EXT4_CLUSTERS_PER_GROUP(sb) / 8);
713 printk(KERN_DEBUG "group %u: stored = %d, counted = %u\n",
714 i, ext4_free_group_clusters(sb, gdp), x);
715 bitmap_count += x;
716 }
717 brelse(bitmap_bh);
718 printk(KERN_DEBUG "ext4_count_free_clusters: stored = %llu"
719 ", computed = %llu, %llu\n",
720 EXT4_NUM_B2C(EXT4_SB(sb), ext4_free_blocks_count(es)),
721 desc_count, bitmap_count);
722 return bitmap_count;
723#else
724 desc_count = 0;
725 for (i = 0; i < ngroups; i++) {
726 gdp = ext4_get_group_desc(sb, i, NULL);
727 if (!gdp)
728 continue;
729 grp = NULL;
730 if (EXT4_SB(sb)->s_group_info)
731 grp = ext4_get_group_info(sb, i);
732 if (!grp || !EXT4_MB_GRP_BBITMAP_CORRUPT(grp))
733 desc_count += ext4_free_group_clusters(sb, gdp);
734 }
735
736 return desc_count;
737#endif
738}
739
740static inline int test_root(ext4_group_t a, int b)
741{
742 while (1) {
743 if (a < b)
744 return 0;
745 if (a == b)
746 return 1;
747 if ((a % b) != 0)
748 return 0;
749 a = a / b;
750 }
751}
752
753/**
754 * ext4_bg_has_super - number of blocks used by the superblock in group
755 * @sb: superblock for filesystem
756 * @group: group number to check
757 *
758 * Return the number of blocks used by the superblock (primary or backup)
759 * in this group. Currently this will be only 0 or 1.
760 */
761int ext4_bg_has_super(struct super_block *sb, ext4_group_t group)
762{
763 struct ext4_super_block *es = EXT4_SB(sb)->s_es;
764
765 if (group == 0)
766 return 1;
767 if (ext4_has_feature_sparse_super2(sb)) {
768 if (group == le32_to_cpu(es->s_backup_bgs[0]) ||
769 group == le32_to_cpu(es->s_backup_bgs[1]))
770 return 1;
771 return 0;
772 }
773 if ((group <= 1) || !ext4_has_feature_sparse_super(sb))
774 return 1;
775 if (!(group & 1))
776 return 0;
777 if (test_root(group, 3) || (test_root(group, 5)) ||
778 test_root(group, 7))
779 return 1;
780
781 return 0;
782}
783
784static unsigned long ext4_bg_num_gdb_meta(struct super_block *sb,
785 ext4_group_t group)
786{
787 unsigned long metagroup = group / EXT4_DESC_PER_BLOCK(sb);
788 ext4_group_t first = metagroup * EXT4_DESC_PER_BLOCK(sb);
789 ext4_group_t last = first + EXT4_DESC_PER_BLOCK(sb) - 1;
790
791 if (group == first || group == first + 1 || group == last)
792 return 1;
793 return 0;
794}
795
796static unsigned long ext4_bg_num_gdb_nometa(struct super_block *sb,
797 ext4_group_t group)
798{
799 if (!ext4_bg_has_super(sb, group))
800 return 0;
801
802 if (ext4_has_feature_meta_bg(sb))
803 return le32_to_cpu(EXT4_SB(sb)->s_es->s_first_meta_bg);
804 else
805 return EXT4_SB(sb)->s_gdb_count;
806}
807
808/**
809 * ext4_bg_num_gdb - number of blocks used by the group table in group
810 * @sb: superblock for filesystem
811 * @group: group number to check
812 *
813 * Return the number of blocks used by the group descriptor table
814 * (primary or backup) in this group. In the future there may be a
815 * different number of descriptor blocks in each group.
816 */
817unsigned long ext4_bg_num_gdb(struct super_block *sb, ext4_group_t group)
818{
819 unsigned long first_meta_bg =
820 le32_to_cpu(EXT4_SB(sb)->s_es->s_first_meta_bg);
821 unsigned long metagroup = group / EXT4_DESC_PER_BLOCK(sb);
822
823 if (!ext4_has_feature_meta_bg(sb) || metagroup < first_meta_bg)
824 return ext4_bg_num_gdb_nometa(sb, group);
825
826 return ext4_bg_num_gdb_meta(sb,group);
827
828}
829
830/*
831 * This function returns the number of file system metadata clusters at
832 * the beginning of a block group, including the reserved gdt blocks.
833 */
834static unsigned ext4_num_base_meta_clusters(struct super_block *sb,
835 ext4_group_t block_group)
836{
837 struct ext4_sb_info *sbi = EXT4_SB(sb);
838 unsigned num;
839
840 /* Check for superblock and gdt backups in this group */
841 num = ext4_bg_has_super(sb, block_group);
842
843 if (!ext4_has_feature_meta_bg(sb) ||
844 block_group < le32_to_cpu(sbi->s_es->s_first_meta_bg) *
845 sbi->s_desc_per_block) {
846 if (num) {
847 num += ext4_bg_num_gdb(sb, block_group);
848 num += le16_to_cpu(sbi->s_es->s_reserved_gdt_blocks);
849 }
850 } else { /* For META_BG_BLOCK_GROUPS */
851 num += ext4_bg_num_gdb(sb, block_group);
852 }
853 return EXT4_NUM_B2C(sbi, num);
854}
855/**
856 * ext4_inode_to_goal_block - return a hint for block allocation
857 * @inode: inode for block allocation
858 *
859 * Return the ideal location to start allocating blocks for a
860 * newly created inode.
861 */
862ext4_fsblk_t ext4_inode_to_goal_block(struct inode *inode)
863{
864 struct ext4_inode_info *ei = EXT4_I(inode);
865 ext4_group_t block_group;
866 ext4_grpblk_t colour;
867 int flex_size = ext4_flex_bg_size(EXT4_SB(inode->i_sb));
868 ext4_fsblk_t bg_start;
869 ext4_fsblk_t last_block;
870
871 block_group = ei->i_block_group;
872 if (flex_size >= EXT4_FLEX_SIZE_DIR_ALLOC_SCHEME) {
873 /*
874 * If there are at least EXT4_FLEX_SIZE_DIR_ALLOC_SCHEME
875 * block groups per flexgroup, reserve the first block
876 * group for directories and special files. Regular
877 * files will start at the second block group. This
878 * tends to speed up directory access and improves
879 * fsck times.
880 */
881 block_group &= ~(flex_size-1);
882 if (S_ISREG(inode->i_mode))
883 block_group++;
884 }
885 bg_start = ext4_group_first_block_no(inode->i_sb, block_group);
886 last_block = ext4_blocks_count(EXT4_SB(inode->i_sb)->s_es) - 1;
887
888 /*
889 * If we are doing delayed allocation, we don't need take
890 * colour into account.
891 */
892 if (test_opt(inode->i_sb, DELALLOC))
893 return bg_start;
894
895 if (bg_start + EXT4_BLOCKS_PER_GROUP(inode->i_sb) <= last_block)
896 colour = (current->pid % 16) *
897 (EXT4_BLOCKS_PER_GROUP(inode->i_sb) / 16);
898 else
899 colour = (current->pid % 16) * ((last_block - bg_start) / 16);
900 return bg_start + colour;
901}
902