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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 ASSERT(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 struct buffer_head *bh_p;
274
275 if (block_group >= ngroups) {
276 ext4_error(sb, "block_group >= groups_count - block_group = %u,"
277 " groups_count = %u", block_group, ngroups);
278
279 return NULL;
280 }
281
282 group_desc = block_group >> EXT4_DESC_PER_BLOCK_BITS(sb);
283 offset = block_group & (EXT4_DESC_PER_BLOCK(sb) - 1);
284 bh_p = sbi_array_rcu_deref(sbi, s_group_desc, group_desc);
285 /*
286 * sbi_array_rcu_deref returns with rcu unlocked, this is ok since
287 * the pointer being dereferenced won't be dereferenced again. By
288 * looking at the usage in add_new_gdb() the value isn't modified,
289 * just the pointer, and so it remains valid.
290 */
291 if (!bh_p) {
292 ext4_error(sb, "Group descriptor not loaded - "
293 "block_group = %u, group_desc = %u, desc = %u",
294 block_group, group_desc, offset);
295 return NULL;
296 }
297
298 desc = (struct ext4_group_desc *)(
299 (__u8 *)bh_p->b_data +
300 offset * EXT4_DESC_SIZE(sb));
301 if (bh)
302 *bh = bh_p;
303 return desc;
304}
305
306/*
307 * Return the block number which was discovered to be invalid, or 0 if
308 * the block bitmap is valid.
309 */
310static ext4_fsblk_t ext4_valid_block_bitmap(struct super_block *sb,
311 struct ext4_group_desc *desc,
312 ext4_group_t block_group,
313 struct buffer_head *bh)
314{
315 struct ext4_sb_info *sbi = EXT4_SB(sb);
316 ext4_grpblk_t offset;
317 ext4_grpblk_t next_zero_bit;
318 ext4_grpblk_t max_bit = EXT4_CLUSTERS_PER_GROUP(sb);
319 ext4_fsblk_t blk;
320 ext4_fsblk_t group_first_block;
321
322 if (ext4_has_feature_flex_bg(sb)) {
323 /* with FLEX_BG, the inode/block bitmaps and itable
324 * blocks may not be in the group at all
325 * so the bitmap validation will be skipped for those groups
326 * or it has to also read the block group where the bitmaps
327 * are located to verify they are set.
328 */
329 return 0;
330 }
331 group_first_block = ext4_group_first_block_no(sb, block_group);
332
333 /* check whether block bitmap block number is set */
334 blk = ext4_block_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 bitmap block number is set */
342 blk = ext4_inode_bitmap(sb, desc);
343 offset = blk - group_first_block;
344 if (offset < 0 || EXT4_B2C(sbi, offset) >= max_bit ||
345 !ext4_test_bit(EXT4_B2C(sbi, offset), bh->b_data))
346 /* bad block bitmap */
347 return blk;
348
349 /* check whether the inode table block number is set */
350 blk = ext4_inode_table(sb, desc);
351 offset = blk - group_first_block;
352 if (offset < 0 || EXT4_B2C(sbi, offset) >= max_bit ||
353 EXT4_B2C(sbi, offset + sbi->s_itb_per_group) >= max_bit)
354 return blk;
355 next_zero_bit = ext4_find_next_zero_bit(bh->b_data,
356 EXT4_B2C(sbi, offset + sbi->s_itb_per_group),
357 EXT4_B2C(sbi, offset));
358 if (next_zero_bit <
359 EXT4_B2C(sbi, offset + sbi->s_itb_per_group))
360 /* bad bitmap for inode tables */
361 return blk;
362 return 0;
363}
364
365static int ext4_validate_block_bitmap(struct super_block *sb,
366 struct ext4_group_desc *desc,
367 ext4_group_t block_group,
368 struct buffer_head *bh)
369{
370 ext4_fsblk_t blk;
371 struct ext4_group_info *grp;
372
373 if (EXT4_SB(sb)->s_mount_state & EXT4_FC_REPLAY)
374 return 0;
375
376 grp = ext4_get_group_info(sb, block_group);
377
378 if (buffer_verified(bh))
379 return 0;
380 if (EXT4_MB_GRP_BBITMAP_CORRUPT(grp))
381 return -EFSCORRUPTED;
382
383 ext4_lock_group(sb, block_group);
384 if (buffer_verified(bh))
385 goto verified;
386 if (unlikely(!ext4_block_bitmap_csum_verify(sb, block_group,
387 desc, bh) ||
388 ext4_simulate_fail(sb, EXT4_SIM_BBITMAP_CRC))) {
389 ext4_unlock_group(sb, block_group);
390 ext4_error(sb, "bg %u: bad block bitmap checksum", block_group);
391 ext4_mark_group_bitmap_corrupted(sb, block_group,
392 EXT4_GROUP_INFO_BBITMAP_CORRUPT);
393 return -EFSBADCRC;
394 }
395 blk = ext4_valid_block_bitmap(sb, desc, block_group, bh);
396 if (unlikely(blk != 0)) {
397 ext4_unlock_group(sb, block_group);
398 ext4_error(sb, "bg %u: block %llu: invalid block bitmap",
399 block_group, blk);
400 ext4_mark_group_bitmap_corrupted(sb, block_group,
401 EXT4_GROUP_INFO_BBITMAP_CORRUPT);
402 return -EFSCORRUPTED;
403 }
404 set_buffer_verified(bh);
405verified:
406 ext4_unlock_group(sb, block_group);
407 return 0;
408}
409
410/**
411 * ext4_read_block_bitmap_nowait()
412 * @sb: super block
413 * @block_group: given block group
414 * @ignore_locked: ignore locked buffers
415 *
416 * Read the bitmap for a given block_group,and validate the
417 * bits for block/inode/inode tables are set in the bitmaps
418 *
419 * Return buffer_head on success or an ERR_PTR in case of failure.
420 */
421struct buffer_head *
422ext4_read_block_bitmap_nowait(struct super_block *sb, ext4_group_t block_group,
423 bool ignore_locked)
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 ext4_mark_group_bitmap_corrupted(sb, block_group,
440 EXT4_GROUP_INFO_BBITMAP_CORRUPT);
441 return ERR_PTR(-EFSCORRUPTED);
442 }
443 bh = sb_getblk(sb, bitmap_blk);
444 if (unlikely(!bh)) {
445 ext4_warning(sb, "Cannot get buffer for block bitmap - "
446 "block_group = %u, block_bitmap = %llu",
447 block_group, bitmap_blk);
448 return ERR_PTR(-ENOMEM);
449 }
450
451 if (ignore_locked && buffer_locked(bh)) {
452 /* buffer under IO already, return if called for prefetching */
453 put_bh(bh);
454 return NULL;
455 }
456
457 if (bitmap_uptodate(bh))
458 goto verify;
459
460 lock_buffer(bh);
461 if (bitmap_uptodate(bh)) {
462 unlock_buffer(bh);
463 goto verify;
464 }
465 ext4_lock_group(sb, block_group);
466 if (ext4_has_group_desc_csum(sb) &&
467 (desc->bg_flags & cpu_to_le16(EXT4_BG_BLOCK_UNINIT))) {
468 if (block_group == 0) {
469 ext4_unlock_group(sb, block_group);
470 unlock_buffer(bh);
471 ext4_error(sb, "Block bitmap for bg 0 marked "
472 "uninitialized");
473 err = -EFSCORRUPTED;
474 goto out;
475 }
476 err = ext4_init_block_bitmap(sb, bh, block_group, desc);
477 set_bitmap_uptodate(bh);
478 set_buffer_uptodate(bh);
479 set_buffer_verified(bh);
480 ext4_unlock_group(sb, block_group);
481 unlock_buffer(bh);
482 if (err) {
483 ext4_error(sb, "Failed to init block bitmap for group "
484 "%u: %d", block_group, err);
485 goto out;
486 }
487 goto verify;
488 }
489 ext4_unlock_group(sb, block_group);
490 if (buffer_uptodate(bh)) {
491 /*
492 * if not uninit if bh is uptodate,
493 * bitmap is also uptodate
494 */
495 set_bitmap_uptodate(bh);
496 unlock_buffer(bh);
497 goto verify;
498 }
499 /*
500 * submit the buffer_head for reading
501 */
502 set_buffer_new(bh);
503 trace_ext4_read_block_bitmap_load(sb, block_group, ignore_locked);
504 ext4_read_bh_nowait(bh, REQ_META | REQ_PRIO |
505 (ignore_locked ? REQ_RAHEAD : 0),
506 ext4_end_bitmap_read);
507 return bh;
508verify:
509 err = ext4_validate_block_bitmap(sb, desc, block_group, bh);
510 if (err)
511 goto out;
512 return bh;
513out:
514 put_bh(bh);
515 return ERR_PTR(err);
516}
517
518/* Returns 0 on success, -errno on error */
519int ext4_wait_block_bitmap(struct super_block *sb, ext4_group_t block_group,
520 struct buffer_head *bh)
521{
522 struct ext4_group_desc *desc;
523
524 if (!buffer_new(bh))
525 return 0;
526 desc = ext4_get_group_desc(sb, block_group, NULL);
527 if (!desc)
528 return -EFSCORRUPTED;
529 wait_on_buffer(bh);
530 ext4_simulate_fail_bh(sb, bh, EXT4_SIM_BBITMAP_EIO);
531 if (!buffer_uptodate(bh)) {
532 ext4_error_err(sb, EIO, "Cannot read block bitmap - "
533 "block_group = %u, block_bitmap = %llu",
534 block_group, (unsigned long long) bh->b_blocknr);
535 ext4_mark_group_bitmap_corrupted(sb, block_group,
536 EXT4_GROUP_INFO_BBITMAP_CORRUPT);
537 return -EIO;
538 }
539 clear_buffer_new(bh);
540 /* Panic or remount fs read-only if block bitmap is invalid */
541 return ext4_validate_block_bitmap(sb, desc, block_group, bh);
542}
543
544struct buffer_head *
545ext4_read_block_bitmap(struct super_block *sb, ext4_group_t block_group)
546{
547 struct buffer_head *bh;
548 int err;
549
550 bh = ext4_read_block_bitmap_nowait(sb, block_group, false);
551 if (IS_ERR(bh))
552 return bh;
553 err = ext4_wait_block_bitmap(sb, block_group, bh);
554 if (err) {
555 put_bh(bh);
556 return ERR_PTR(err);
557 }
558 return bh;
559}
560
561/**
562 * ext4_has_free_clusters()
563 * @sbi: in-core super block structure.
564 * @nclusters: number of needed blocks
565 * @flags: flags from ext4_mb_new_blocks()
566 *
567 * Check if filesystem has nclusters free & available for allocation.
568 * On success return 1, return 0 on failure.
569 */
570static int ext4_has_free_clusters(struct ext4_sb_info *sbi,
571 s64 nclusters, unsigned int flags)
572{
573 s64 free_clusters, dirty_clusters, rsv, resv_clusters;
574 struct percpu_counter *fcc = &sbi->s_freeclusters_counter;
575 struct percpu_counter *dcc = &sbi->s_dirtyclusters_counter;
576
577 free_clusters = percpu_counter_read_positive(fcc);
578 dirty_clusters = percpu_counter_read_positive(dcc);
579 resv_clusters = atomic64_read(&sbi->s_resv_clusters);
580
581 /*
582 * r_blocks_count should always be multiple of the cluster ratio so
583 * we are safe to do a plane bit shift only.
584 */
585 rsv = (ext4_r_blocks_count(sbi->s_es) >> sbi->s_cluster_bits) +
586 resv_clusters;
587
588 if (free_clusters - (nclusters + rsv + dirty_clusters) <
589 EXT4_FREECLUSTERS_WATERMARK) {
590 free_clusters = percpu_counter_sum_positive(fcc);
591 dirty_clusters = percpu_counter_sum_positive(dcc);
592 }
593 /* Check whether we have space after accounting for current
594 * dirty clusters & root reserved clusters.
595 */
596 if (free_clusters >= (rsv + nclusters + dirty_clusters))
597 return 1;
598
599 /* Hm, nope. Are (enough) root reserved clusters available? */
600 if (uid_eq(sbi->s_resuid, current_fsuid()) ||
601 (!gid_eq(sbi->s_resgid, GLOBAL_ROOT_GID) && in_group_p(sbi->s_resgid)) ||
602 capable(CAP_SYS_RESOURCE) ||
603 (flags & EXT4_MB_USE_ROOT_BLOCKS)) {
604
605 if (free_clusters >= (nclusters + dirty_clusters +
606 resv_clusters))
607 return 1;
608 }
609 /* No free blocks. Let's see if we can dip into reserved pool */
610 if (flags & EXT4_MB_USE_RESERVED) {
611 if (free_clusters >= (nclusters + dirty_clusters))
612 return 1;
613 }
614
615 return 0;
616}
617
618int ext4_claim_free_clusters(struct ext4_sb_info *sbi,
619 s64 nclusters, unsigned int flags)
620{
621 if (ext4_has_free_clusters(sbi, nclusters, flags)) {
622 percpu_counter_add(&sbi->s_dirtyclusters_counter, nclusters);
623 return 0;
624 } else
625 return -ENOSPC;
626}
627
628/**
629 * ext4_should_retry_alloc() - check if a block allocation should be retried
630 * @sb: superblock
631 * @retries: number of retry attempts made so far
632 *
633 * ext4_should_retry_alloc() is called when ENOSPC is returned while
634 * attempting to allocate blocks. If there's an indication that a pending
635 * journal transaction might free some space and allow another attempt to
636 * succeed, this function will wait for the current or committing transaction
637 * to complete and then return TRUE.
638 */
639int ext4_should_retry_alloc(struct super_block *sb, int *retries)
640{
641 struct ext4_sb_info *sbi = EXT4_SB(sb);
642
643 if (!sbi->s_journal)
644 return 0;
645
646 if (++(*retries) > 3) {
647 percpu_counter_inc(&sbi->s_sra_exceeded_retry_limit);
648 return 0;
649 }
650
651 /*
652 * if there's no indication that blocks are about to be freed it's
653 * possible we just missed a transaction commit that did so
654 */
655 smp_mb();
656 if (sbi->s_mb_free_pending == 0) {
657 if (test_opt(sb, DISCARD)) {
658 atomic_inc(&sbi->s_retry_alloc_pending);
659 flush_work(&sbi->s_discard_work);
660 atomic_dec(&sbi->s_retry_alloc_pending);
661 }
662 return ext4_has_free_clusters(sbi, 1, 0);
663 }
664
665 /*
666 * it's possible we've just missed a transaction commit here,
667 * so ignore the returned status
668 */
669 ext4_debug("%s: retrying operation after ENOSPC\n", sb->s_id);
670 (void) jbd2_journal_force_commit_nested(sbi->s_journal);
671 return 1;
672}
673
674/*
675 * ext4_new_meta_blocks() -- allocate block for meta data (indexing) blocks
676 *
677 * @handle: handle to this transaction
678 * @inode: file inode
679 * @goal: given target block(filesystem wide)
680 * @count: pointer to total number of clusters needed
681 * @errp: error code
682 *
683 * Return 1st allocated block number on success, *count stores total account
684 * error stores in errp pointer
685 */
686ext4_fsblk_t ext4_new_meta_blocks(handle_t *handle, struct inode *inode,
687 ext4_fsblk_t goal, unsigned int flags,
688 unsigned long *count, int *errp)
689{
690 struct ext4_allocation_request ar;
691 ext4_fsblk_t ret;
692
693 memset(&ar, 0, sizeof(ar));
694 /* Fill with neighbour allocated blocks */
695 ar.inode = inode;
696 ar.goal = goal;
697 ar.len = count ? *count : 1;
698 ar.flags = flags;
699
700 ret = ext4_mb_new_blocks(handle, &ar, errp);
701 if (count)
702 *count = ar.len;
703 /*
704 * Account for the allocated meta blocks. We will never
705 * fail EDQUOT for metdata, but we do account for it.
706 */
707 if (!(*errp) && (flags & EXT4_MB_DELALLOC_RESERVED)) {
708 dquot_alloc_block_nofail(inode,
709 EXT4_C2B(EXT4_SB(inode->i_sb), ar.len));
710 }
711 return ret;
712}
713
714/**
715 * ext4_count_free_clusters() -- count filesystem free clusters
716 * @sb: superblock
717 *
718 * Adds up the number of free clusters from each block group.
719 */
720ext4_fsblk_t ext4_count_free_clusters(struct super_block *sb)
721{
722 ext4_fsblk_t desc_count;
723 struct ext4_group_desc *gdp;
724 ext4_group_t i;
725 ext4_group_t ngroups = ext4_get_groups_count(sb);
726 struct ext4_group_info *grp;
727#ifdef EXT4FS_DEBUG
728 struct ext4_super_block *es;
729 ext4_fsblk_t bitmap_count;
730 unsigned int x;
731 struct buffer_head *bitmap_bh = NULL;
732
733 es = EXT4_SB(sb)->s_es;
734 desc_count = 0;
735 bitmap_count = 0;
736 gdp = NULL;
737
738 for (i = 0; i < ngroups; i++) {
739 gdp = ext4_get_group_desc(sb, i, NULL);
740 if (!gdp)
741 continue;
742 grp = NULL;
743 if (EXT4_SB(sb)->s_group_info)
744 grp = ext4_get_group_info(sb, i);
745 if (!grp || !EXT4_MB_GRP_BBITMAP_CORRUPT(grp))
746 desc_count += ext4_free_group_clusters(sb, gdp);
747 brelse(bitmap_bh);
748 bitmap_bh = ext4_read_block_bitmap(sb, i);
749 if (IS_ERR(bitmap_bh)) {
750 bitmap_bh = NULL;
751 continue;
752 }
753
754 x = ext4_count_free(bitmap_bh->b_data,
755 EXT4_CLUSTERS_PER_GROUP(sb) / 8);
756 printk(KERN_DEBUG "group %u: stored = %d, counted = %u\n",
757 i, ext4_free_group_clusters(sb, gdp), x);
758 bitmap_count += x;
759 }
760 brelse(bitmap_bh);
761 printk(KERN_DEBUG "ext4_count_free_clusters: stored = %llu"
762 ", computed = %llu, %llu\n",
763 EXT4_NUM_B2C(EXT4_SB(sb), ext4_free_blocks_count(es)),
764 desc_count, bitmap_count);
765 return bitmap_count;
766#else
767 desc_count = 0;
768 for (i = 0; i < ngroups; i++) {
769 gdp = ext4_get_group_desc(sb, i, NULL);
770 if (!gdp)
771 continue;
772 grp = NULL;
773 if (EXT4_SB(sb)->s_group_info)
774 grp = ext4_get_group_info(sb, i);
775 if (!grp || !EXT4_MB_GRP_BBITMAP_CORRUPT(grp))
776 desc_count += ext4_free_group_clusters(sb, gdp);
777 }
778
779 return desc_count;
780#endif
781}
782
783static inline int test_root(ext4_group_t a, int b)
784{
785 while (1) {
786 if (a < b)
787 return 0;
788 if (a == b)
789 return 1;
790 if ((a % b) != 0)
791 return 0;
792 a = a / b;
793 }
794}
795
796/**
797 * ext4_bg_has_super - number of blocks used by the superblock in group
798 * @sb: superblock for filesystem
799 * @group: group number to check
800 *
801 * Return the number of blocks used by the superblock (primary or backup)
802 * in this group. Currently this will be only 0 or 1.
803 */
804int ext4_bg_has_super(struct super_block *sb, ext4_group_t group)
805{
806 struct ext4_super_block *es = EXT4_SB(sb)->s_es;
807
808 if (group == 0)
809 return 1;
810 if (ext4_has_feature_sparse_super2(sb)) {
811 if (group == le32_to_cpu(es->s_backup_bgs[0]) ||
812 group == le32_to_cpu(es->s_backup_bgs[1]))
813 return 1;
814 return 0;
815 }
816 if ((group <= 1) || !ext4_has_feature_sparse_super(sb))
817 return 1;
818 if (!(group & 1))
819 return 0;
820 if (test_root(group, 3) || (test_root(group, 5)) ||
821 test_root(group, 7))
822 return 1;
823
824 return 0;
825}
826
827static unsigned long ext4_bg_num_gdb_meta(struct super_block *sb,
828 ext4_group_t group)
829{
830 unsigned long metagroup = group / EXT4_DESC_PER_BLOCK(sb);
831 ext4_group_t first = metagroup * EXT4_DESC_PER_BLOCK(sb);
832 ext4_group_t last = first + EXT4_DESC_PER_BLOCK(sb) - 1;
833
834 if (group == first || group == first + 1 || group == last)
835 return 1;
836 return 0;
837}
838
839static unsigned long ext4_bg_num_gdb_nometa(struct super_block *sb,
840 ext4_group_t group)
841{
842 if (!ext4_bg_has_super(sb, group))
843 return 0;
844
845 if (ext4_has_feature_meta_bg(sb))
846 return le32_to_cpu(EXT4_SB(sb)->s_es->s_first_meta_bg);
847 else
848 return EXT4_SB(sb)->s_gdb_count;
849}
850
851/**
852 * ext4_bg_num_gdb - number of blocks used by the group table in group
853 * @sb: superblock for filesystem
854 * @group: group number to check
855 *
856 * Return the number of blocks used by the group descriptor table
857 * (primary or backup) in this group. In the future there may be a
858 * different number of descriptor blocks in each group.
859 */
860unsigned long ext4_bg_num_gdb(struct super_block *sb, ext4_group_t group)
861{
862 unsigned long first_meta_bg =
863 le32_to_cpu(EXT4_SB(sb)->s_es->s_first_meta_bg);
864 unsigned long metagroup = group / EXT4_DESC_PER_BLOCK(sb);
865
866 if (!ext4_has_feature_meta_bg(sb) || metagroup < first_meta_bg)
867 return ext4_bg_num_gdb_nometa(sb, group);
868
869 return ext4_bg_num_gdb_meta(sb,group);
870
871}
872
873/*
874 * This function returns the number of file system metadata clusters at
875 * the beginning of a block group, including the reserved gdt blocks.
876 */
877static unsigned ext4_num_base_meta_clusters(struct super_block *sb,
878 ext4_group_t block_group)
879{
880 struct ext4_sb_info *sbi = EXT4_SB(sb);
881 unsigned num;
882
883 /* Check for superblock and gdt backups in this group */
884 num = ext4_bg_has_super(sb, block_group);
885
886 if (!ext4_has_feature_meta_bg(sb) ||
887 block_group < le32_to_cpu(sbi->s_es->s_first_meta_bg) *
888 sbi->s_desc_per_block) {
889 if (num) {
890 num += ext4_bg_num_gdb(sb, block_group);
891 num += le16_to_cpu(sbi->s_es->s_reserved_gdt_blocks);
892 }
893 } else { /* For META_BG_BLOCK_GROUPS */
894 num += ext4_bg_num_gdb(sb, block_group);
895 }
896 return EXT4_NUM_B2C(sbi, num);
897}
898/**
899 * ext4_inode_to_goal_block - return a hint for block allocation
900 * @inode: inode for block allocation
901 *
902 * Return the ideal location to start allocating blocks for a
903 * newly created inode.
904 */
905ext4_fsblk_t ext4_inode_to_goal_block(struct inode *inode)
906{
907 struct ext4_inode_info *ei = EXT4_I(inode);
908 ext4_group_t block_group;
909 ext4_grpblk_t colour;
910 int flex_size = ext4_flex_bg_size(EXT4_SB(inode->i_sb));
911 ext4_fsblk_t bg_start;
912 ext4_fsblk_t last_block;
913
914 block_group = ei->i_block_group;
915 if (flex_size >= EXT4_FLEX_SIZE_DIR_ALLOC_SCHEME) {
916 /*
917 * If there are at least EXT4_FLEX_SIZE_DIR_ALLOC_SCHEME
918 * block groups per flexgroup, reserve the first block
919 * group for directories and special files. Regular
920 * files will start at the second block group. This
921 * tends to speed up directory access and improves
922 * fsck times.
923 */
924 block_group &= ~(flex_size-1);
925 if (S_ISREG(inode->i_mode))
926 block_group++;
927 }
928 bg_start = ext4_group_first_block_no(inode->i_sb, block_group);
929 last_block = ext4_blocks_count(EXT4_SB(inode->i_sb)->s_es) - 1;
930
931 /*
932 * If we are doing delayed allocation, we don't need take
933 * colour into account.
934 */
935 if (test_opt(inode->i_sb, DELALLOC))
936 return bg_start;
937
938 if (bg_start + EXT4_BLOCKS_PER_GROUP(inode->i_sb) <= last_block)
939 colour = (task_pid_nr(current) % 16) *
940 (EXT4_BLOCKS_PER_GROUP(inode->i_sb) / 16);
941 else
942 colour = (task_pid_nr(current) % 16) *
943 ((last_block - bg_start) / 16);
944 return bg_start + colour;
945}
946
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 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 */
86unsigned 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 */
179void ext4_init_block_bitmap(struct super_block *sb, struct buffer_head *bh,
180 ext4_group_t block_group,
181 struct ext4_group_desc *gdp)
182{
183 unsigned int bit, bit_max;
184 struct ext4_sb_info *sbi = EXT4_SB(sb);
185 ext4_fsblk_t start, tmp;
186 int flex_bg = 0;
187 struct ext4_group_info *grp;
188
189 J_ASSERT_BH(bh, buffer_locked(bh));
190
191 /* If checksum is bad mark all blocks used to prevent allocation
192 * essentially implementing a per-group read-only flag. */
193 if (!ext4_group_desc_csum_verify(sb, block_group, gdp)) {
194 ext4_error(sb, "Checksum bad for group %u", block_group);
195 grp = ext4_get_group_info(sb, block_group);
196 set_bit(EXT4_GROUP_INFO_BBITMAP_CORRUPT_BIT, &grp->bb_state);
197 set_bit(EXT4_GROUP_INFO_IBITMAP_CORRUPT_BIT, &grp->bb_state);
198 return;
199 }
200 memset(bh->b_data, 0, sb->s_blocksize);
201
202 bit_max = ext4_num_base_meta_clusters(sb, block_group);
203 for (bit = 0; bit < bit_max; bit++)
204 ext4_set_bit(bit, bh->b_data);
205
206 start = ext4_group_first_block_no(sb, block_group);
207
208 if (EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_FLEX_BG))
209 flex_bg = 1;
210
211 /* Set bits for block and inode bitmaps, and inode table */
212 tmp = ext4_block_bitmap(sb, gdp);
213 if (!flex_bg || ext4_block_in_group(sb, tmp, block_group))
214 ext4_set_bit(EXT4_B2C(sbi, tmp - start), bh->b_data);
215
216 tmp = ext4_inode_bitmap(sb, gdp);
217 if (!flex_bg || ext4_block_in_group(sb, tmp, block_group))
218 ext4_set_bit(EXT4_B2C(sbi, tmp - start), bh->b_data);
219
220 tmp = ext4_inode_table(sb, gdp);
221 for (; tmp < ext4_inode_table(sb, gdp) +
222 sbi->s_itb_per_group; tmp++) {
223 if (!flex_bg || ext4_block_in_group(sb, tmp, block_group))
224 ext4_set_bit(EXT4_B2C(sbi, tmp - start), bh->b_data);
225 }
226
227 /*
228 * Also if the number of blocks within the group is less than
229 * the blocksize * 8 ( which is the size of bitmap ), set rest
230 * of the block bitmap to 1
231 */
232 ext4_mark_bitmap_end(num_clusters_in_group(sb, block_group),
233 sb->s_blocksize * 8, bh->b_data);
234 ext4_block_bitmap_csum_set(sb, block_group, gdp, bh);
235 ext4_group_desc_csum_set(sb, block_group, gdp);
236}
237
238/* Return the number of free blocks in a block group. It is used when
239 * the block bitmap is uninitialized, so we can't just count the bits
240 * in the bitmap. */
241unsigned ext4_free_clusters_after_init(struct super_block *sb,
242 ext4_group_t block_group,
243 struct ext4_group_desc *gdp)
244{
245 return num_clusters_in_group(sb, block_group) -
246 ext4_num_overhead_clusters(sb, block_group, gdp);
247}
248
249/*
250 * The free blocks are managed by bitmaps. A file system contains several
251 * blocks groups. Each group contains 1 bitmap block for blocks, 1 bitmap
252 * block for inodes, N blocks for the inode table and data blocks.
253 *
254 * The file system contains group descriptors which are located after the
255 * super block. Each descriptor contains the number of the bitmap block and
256 * the free blocks count in the block. The descriptors are loaded in memory
257 * when a file system is mounted (see ext4_fill_super).
258 */
259
260/**
261 * ext4_get_group_desc() -- load group descriptor from disk
262 * @sb: super block
263 * @block_group: given block group
264 * @bh: pointer to the buffer head to store the block
265 * group descriptor
266 */
267struct ext4_group_desc * ext4_get_group_desc(struct super_block *sb,
268 ext4_group_t block_group,
269 struct buffer_head **bh)
270{
271 unsigned int group_desc;
272 unsigned int offset;
273 ext4_group_t ngroups = ext4_get_groups_count(sb);
274 struct ext4_group_desc *desc;
275 struct ext4_sb_info *sbi = EXT4_SB(sb);
276
277 if (block_group >= ngroups) {
278 ext4_error(sb, "block_group >= groups_count - block_group = %u,"
279 " groups_count = %u", block_group, ngroups);
280
281 return NULL;
282 }
283
284 group_desc = block_group >> EXT4_DESC_PER_BLOCK_BITS(sb);
285 offset = block_group & (EXT4_DESC_PER_BLOCK(sb) - 1);
286 if (!sbi->s_group_desc[group_desc]) {
287 ext4_error(sb, "Group descriptor not loaded - "
288 "block_group = %u, group_desc = %u, desc = %u",
289 block_group, group_desc, offset);
290 return NULL;
291 }
292
293 desc = (struct ext4_group_desc *)(
294 (__u8 *)sbi->s_group_desc[group_desc]->b_data +
295 offset * EXT4_DESC_SIZE(sb));
296 if (bh)
297 *bh = sbi->s_group_desc[group_desc];
298 return desc;
299}
300
301/*
302 * Return the block number which was discovered to be invalid, or 0 if
303 * the block bitmap is valid.
304 */
305static ext4_fsblk_t ext4_valid_block_bitmap(struct super_block *sb,
306 struct ext4_group_desc *desc,
307 ext4_group_t block_group,
308 struct buffer_head *bh)
309{
310 ext4_grpblk_t offset;
311 ext4_grpblk_t next_zero_bit;
312 ext4_fsblk_t blk;
313 ext4_fsblk_t group_first_block;
314
315 if (EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_FLEX_BG)) {
316 /* with FLEX_BG, the inode/block bitmaps and itable
317 * blocks may not be in the group at all
318 * so the bitmap validation will be skipped for those groups
319 * or it has to also read the block group where the bitmaps
320 * are located to verify they are set.
321 */
322 return 0;
323 }
324 group_first_block = ext4_group_first_block_no(sb, block_group);
325
326 /* check whether block bitmap block number is set */
327 blk = ext4_block_bitmap(sb, desc);
328 offset = blk - group_first_block;
329 if (!ext4_test_bit(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 (!ext4_test_bit(offset, bh->b_data))
337 /* bad block bitmap */
338 return blk;
339
340 /* check whether the inode table block number is set */
341 blk = ext4_inode_table(sb, desc);
342 offset = blk - group_first_block;
343 next_zero_bit = ext4_find_next_zero_bit(bh->b_data,
344 offset + EXT4_SB(sb)->s_itb_per_group,
345 offset);
346 if (next_zero_bit < offset + EXT4_SB(sb)->s_itb_per_group)
347 /* bad bitmap for inode tables */
348 return blk;
349 return 0;
350}
351
352void ext4_validate_block_bitmap(struct super_block *sb,
353 struct ext4_group_desc *desc,
354 ext4_group_t block_group,
355 struct buffer_head *bh)
356{
357 ext4_fsblk_t blk;
358 struct ext4_group_info *grp = ext4_get_group_info(sb, block_group);
359
360 if (buffer_verified(bh))
361 return;
362
363 ext4_lock_group(sb, block_group);
364 blk = ext4_valid_block_bitmap(sb, desc, block_group, bh);
365 if (unlikely(blk != 0)) {
366 ext4_unlock_group(sb, block_group);
367 ext4_error(sb, "bg %u: block %llu: invalid block bitmap",
368 block_group, blk);
369 set_bit(EXT4_GROUP_INFO_BBITMAP_CORRUPT_BIT, &grp->bb_state);
370 return;
371 }
372 if (unlikely(!ext4_block_bitmap_csum_verify(sb, block_group,
373 desc, bh))) {
374 ext4_unlock_group(sb, block_group);
375 ext4_error(sb, "bg %u: bad block bitmap checksum", block_group);
376 set_bit(EXT4_GROUP_INFO_BBITMAP_CORRUPT_BIT, &grp->bb_state);
377 return;
378 }
379 set_buffer_verified(bh);
380 ext4_unlock_group(sb, block_group);
381}
382
383/**
384 * ext4_read_block_bitmap_nowait()
385 * @sb: super block
386 * @block_group: given block group
387 *
388 * Read the bitmap for a given block_group,and validate the
389 * bits for block/inode/inode tables are set in the bitmaps
390 *
391 * Return buffer_head on success or NULL in case of failure.
392 */
393struct buffer_head *
394ext4_read_block_bitmap_nowait(struct super_block *sb, ext4_group_t block_group)
395{
396 struct ext4_group_desc *desc;
397 struct buffer_head *bh;
398 ext4_fsblk_t bitmap_blk;
399
400 desc = ext4_get_group_desc(sb, block_group, NULL);
401 if (!desc)
402 return NULL;
403 bitmap_blk = ext4_block_bitmap(sb, desc);
404 bh = sb_getblk(sb, bitmap_blk);
405 if (unlikely(!bh)) {
406 ext4_error(sb, "Cannot get buffer for block bitmap - "
407 "block_group = %u, block_bitmap = %llu",
408 block_group, bitmap_blk);
409 return NULL;
410 }
411
412 if (bitmap_uptodate(bh))
413 goto verify;
414
415 lock_buffer(bh);
416 if (bitmap_uptodate(bh)) {
417 unlock_buffer(bh);
418 goto verify;
419 }
420 ext4_lock_group(sb, block_group);
421 if (desc->bg_flags & cpu_to_le16(EXT4_BG_BLOCK_UNINIT)) {
422 ext4_init_block_bitmap(sb, bh, block_group, desc);
423 set_bitmap_uptodate(bh);
424 set_buffer_uptodate(bh);
425 ext4_unlock_group(sb, block_group);
426 unlock_buffer(bh);
427 return bh;
428 }
429 ext4_unlock_group(sb, block_group);
430 if (buffer_uptodate(bh)) {
431 /*
432 * if not uninit if bh is uptodate,
433 * bitmap is also uptodate
434 */
435 set_bitmap_uptodate(bh);
436 unlock_buffer(bh);
437 goto verify;
438 }
439 /*
440 * submit the buffer_head for reading
441 */
442 set_buffer_new(bh);
443 trace_ext4_read_block_bitmap_load(sb, block_group);
444 bh->b_end_io = ext4_end_bitmap_read;
445 get_bh(bh);
446 submit_bh(READ | REQ_META | REQ_PRIO, bh);
447 return bh;
448verify:
449 ext4_validate_block_bitmap(sb, desc, block_group, bh);
450 if (buffer_verified(bh))
451 return bh;
452 put_bh(bh);
453 return NULL;
454}
455
456/* Returns 0 on success, 1 on error */
457int ext4_wait_block_bitmap(struct super_block *sb, ext4_group_t block_group,
458 struct buffer_head *bh)
459{
460 struct ext4_group_desc *desc;
461
462 if (!buffer_new(bh))
463 return 0;
464 desc = ext4_get_group_desc(sb, block_group, NULL);
465 if (!desc)
466 return 1;
467 wait_on_buffer(bh);
468 if (!buffer_uptodate(bh)) {
469 ext4_error(sb, "Cannot read block bitmap - "
470 "block_group = %u, block_bitmap = %llu",
471 block_group, (unsigned long long) bh->b_blocknr);
472 return 1;
473 }
474 clear_buffer_new(bh);
475 /* Panic or remount fs read-only if block bitmap is invalid */
476 ext4_validate_block_bitmap(sb, desc, block_group, bh);
477 /* ...but check for error just in case errors=continue. */
478 return !buffer_verified(bh);
479}
480
481struct buffer_head *
482ext4_read_block_bitmap(struct super_block *sb, ext4_group_t block_group)
483{
484 struct buffer_head *bh;
485
486 bh = ext4_read_block_bitmap_nowait(sb, block_group);
487 if (!bh)
488 return NULL;
489 if (ext4_wait_block_bitmap(sb, block_group, bh)) {
490 put_bh(bh);
491 return NULL;
492 }
493 return bh;
494}
495
496/**
497 * ext4_has_free_clusters()
498 * @sbi: in-core super block structure.
499 * @nclusters: number of needed blocks
500 * @flags: flags from ext4_mb_new_blocks()
501 *
502 * Check if filesystem has nclusters free & available for allocation.
503 * On success return 1, return 0 on failure.
504 */
505static int ext4_has_free_clusters(struct ext4_sb_info *sbi,
506 s64 nclusters, unsigned int flags)
507{
508 s64 free_clusters, dirty_clusters, rsv, resv_clusters;
509 struct percpu_counter *fcc = &sbi->s_freeclusters_counter;
510 struct percpu_counter *dcc = &sbi->s_dirtyclusters_counter;
511
512 free_clusters = percpu_counter_read_positive(fcc);
513 dirty_clusters = percpu_counter_read_positive(dcc);
514 resv_clusters = atomic64_read(&sbi->s_resv_clusters);
515
516 /*
517 * r_blocks_count should always be multiple of the cluster ratio so
518 * we are safe to do a plane bit shift only.
519 */
520 rsv = (ext4_r_blocks_count(sbi->s_es) >> sbi->s_cluster_bits) +
521 resv_clusters;
522
523 if (free_clusters - (nclusters + rsv + dirty_clusters) <
524 EXT4_FREECLUSTERS_WATERMARK) {
525 free_clusters = percpu_counter_sum_positive(fcc);
526 dirty_clusters = percpu_counter_sum_positive(dcc);
527 }
528 /* Check whether we have space after accounting for current
529 * dirty clusters & root reserved clusters.
530 */
531 if (free_clusters >= (rsv + nclusters + dirty_clusters))
532 return 1;
533
534 /* Hm, nope. Are (enough) root reserved clusters available? */
535 if (uid_eq(sbi->s_resuid, current_fsuid()) ||
536 (!gid_eq(sbi->s_resgid, GLOBAL_ROOT_GID) && in_group_p(sbi->s_resgid)) ||
537 capable(CAP_SYS_RESOURCE) ||
538 (flags & EXT4_MB_USE_ROOT_BLOCKS)) {
539
540 if (free_clusters >= (nclusters + dirty_clusters +
541 resv_clusters))
542 return 1;
543 }
544 /* No free blocks. Let's see if we can dip into reserved pool */
545 if (flags & EXT4_MB_USE_RESERVED) {
546 if (free_clusters >= (nclusters + dirty_clusters))
547 return 1;
548 }
549
550 return 0;
551}
552
553int ext4_claim_free_clusters(struct ext4_sb_info *sbi,
554 s64 nclusters, unsigned int flags)
555{
556 if (ext4_has_free_clusters(sbi, nclusters, flags)) {
557 percpu_counter_add(&sbi->s_dirtyclusters_counter, nclusters);
558 return 0;
559 } else
560 return -ENOSPC;
561}
562
563/**
564 * ext4_should_retry_alloc()
565 * @sb: super block
566 * @retries number of attemps has been made
567 *
568 * ext4_should_retry_alloc() is called when ENOSPC is returned, and if
569 * it is profitable to retry the operation, this function will wait
570 * for the current or committing transaction to complete, and then
571 * return TRUE.
572 *
573 * if the total number of retries exceed three times, return FALSE.
574 */
575int ext4_should_retry_alloc(struct super_block *sb, int *retries)
576{
577 if (!ext4_has_free_clusters(EXT4_SB(sb), 1, 0) ||
578 (*retries)++ > 3 ||
579 !EXT4_SB(sb)->s_journal)
580 return 0;
581
582 jbd_debug(1, "%s: retrying operation after ENOSPC\n", sb->s_id);
583
584 return jbd2_journal_force_commit_nested(EXT4_SB(sb)->s_journal);
585}
586
587/*
588 * ext4_new_meta_blocks() -- allocate block for meta data (indexing) blocks
589 *
590 * @handle: handle to this transaction
591 * @inode: file inode
592 * @goal: given target block(filesystem wide)
593 * @count: pointer to total number of clusters needed
594 * @errp: error code
595 *
596 * Return 1st allocated block number on success, *count stores total account
597 * error stores in errp pointer
598 */
599ext4_fsblk_t ext4_new_meta_blocks(handle_t *handle, struct inode *inode,
600 ext4_fsblk_t goal, unsigned int flags,
601 unsigned long *count, int *errp)
602{
603 struct ext4_allocation_request ar;
604 ext4_fsblk_t ret;
605
606 memset(&ar, 0, sizeof(ar));
607 /* Fill with neighbour allocated blocks */
608 ar.inode = inode;
609 ar.goal = goal;
610 ar.len = count ? *count : 1;
611 ar.flags = flags;
612
613 ret = ext4_mb_new_blocks(handle, &ar, errp);
614 if (count)
615 *count = ar.len;
616 /*
617 * Account for the allocated meta blocks. We will never
618 * fail EDQUOT for metdata, but we do account for it.
619 */
620 if (!(*errp) &&
621 ext4_test_inode_state(inode, EXT4_STATE_DELALLOC_RESERVED)) {
622 spin_lock(&EXT4_I(inode)->i_block_reservation_lock);
623 EXT4_I(inode)->i_allocated_meta_blocks += ar.len;
624 spin_unlock(&EXT4_I(inode)->i_block_reservation_lock);
625 dquot_alloc_block_nofail(inode,
626 EXT4_C2B(EXT4_SB(inode->i_sb), ar.len));
627 }
628 return ret;
629}
630
631/**
632 * ext4_count_free_clusters() -- count filesystem free clusters
633 * @sb: superblock
634 *
635 * Adds up the number of free clusters from each block group.
636 */
637ext4_fsblk_t ext4_count_free_clusters(struct super_block *sb)
638{
639 ext4_fsblk_t desc_count;
640 struct ext4_group_desc *gdp;
641 ext4_group_t i;
642 ext4_group_t ngroups = ext4_get_groups_count(sb);
643 struct ext4_group_info *grp;
644#ifdef EXT4FS_DEBUG
645 struct ext4_super_block *es;
646 ext4_fsblk_t bitmap_count;
647 unsigned int x;
648 struct buffer_head *bitmap_bh = NULL;
649
650 es = EXT4_SB(sb)->s_es;
651 desc_count = 0;
652 bitmap_count = 0;
653 gdp = NULL;
654
655 for (i = 0; i < ngroups; i++) {
656 gdp = ext4_get_group_desc(sb, i, NULL);
657 if (!gdp)
658 continue;
659 grp = NULL;
660 if (EXT4_SB(sb)->s_group_info)
661 grp = ext4_get_group_info(sb, i);
662 if (!grp || !EXT4_MB_GRP_BBITMAP_CORRUPT(grp))
663 desc_count += ext4_free_group_clusters(sb, gdp);
664 brelse(bitmap_bh);
665 bitmap_bh = ext4_read_block_bitmap(sb, i);
666 if (bitmap_bh == NULL)
667 continue;
668
669 x = ext4_count_free(bitmap_bh->b_data,
670 EXT4_CLUSTERS_PER_GROUP(sb) / 8);
671 printk(KERN_DEBUG "group %u: stored = %d, counted = %u\n",
672 i, ext4_free_group_clusters(sb, gdp), x);
673 bitmap_count += x;
674 }
675 brelse(bitmap_bh);
676 printk(KERN_DEBUG "ext4_count_free_clusters: stored = %llu"
677 ", computed = %llu, %llu\n",
678 EXT4_NUM_B2C(EXT4_SB(sb), ext4_free_blocks_count(es)),
679 desc_count, bitmap_count);
680 return bitmap_count;
681#else
682 desc_count = 0;
683 for (i = 0; i < ngroups; i++) {
684 gdp = ext4_get_group_desc(sb, i, NULL);
685 if (!gdp)
686 continue;
687 grp = NULL;
688 if (EXT4_SB(sb)->s_group_info)
689 grp = ext4_get_group_info(sb, i);
690 if (!grp || !EXT4_MB_GRP_BBITMAP_CORRUPT(grp))
691 desc_count += ext4_free_group_clusters(sb, gdp);
692 }
693
694 return desc_count;
695#endif
696}
697
698static inline int test_root(ext4_group_t a, int b)
699{
700 while (1) {
701 if (a < b)
702 return 0;
703 if (a == b)
704 return 1;
705 if ((a % b) != 0)
706 return 0;
707 a = a / b;
708 }
709}
710
711static int ext4_group_sparse(ext4_group_t group)
712{
713 if (group <= 1)
714 return 1;
715 if (!(group & 1))
716 return 0;
717 return (test_root(group, 7) || test_root(group, 5) ||
718 test_root(group, 3));
719}
720
721/**
722 * ext4_bg_has_super - number of blocks used by the superblock in group
723 * @sb: superblock for filesystem
724 * @group: group number to check
725 *
726 * Return the number of blocks used by the superblock (primary or backup)
727 * in this group. Currently this will be only 0 or 1.
728 */
729int ext4_bg_has_super(struct super_block *sb, ext4_group_t group)
730{
731 if (EXT4_HAS_RO_COMPAT_FEATURE(sb,
732 EXT4_FEATURE_RO_COMPAT_SPARSE_SUPER) &&
733 !ext4_group_sparse(group))
734 return 0;
735 return 1;
736}
737
738static unsigned long ext4_bg_num_gdb_meta(struct super_block *sb,
739 ext4_group_t group)
740{
741 unsigned long metagroup = group / EXT4_DESC_PER_BLOCK(sb);
742 ext4_group_t first = metagroup * EXT4_DESC_PER_BLOCK(sb);
743 ext4_group_t last = first + EXT4_DESC_PER_BLOCK(sb) - 1;
744
745 if (group == first || group == first + 1 || group == last)
746 return 1;
747 return 0;
748}
749
750static unsigned long ext4_bg_num_gdb_nometa(struct super_block *sb,
751 ext4_group_t group)
752{
753 if (!ext4_bg_has_super(sb, group))
754 return 0;
755
756 if (EXT4_HAS_INCOMPAT_FEATURE(sb,EXT4_FEATURE_INCOMPAT_META_BG))
757 return le32_to_cpu(EXT4_SB(sb)->s_es->s_first_meta_bg);
758 else
759 return EXT4_SB(sb)->s_gdb_count;
760}
761
762/**
763 * ext4_bg_num_gdb - number of blocks used by the group table in group
764 * @sb: superblock for filesystem
765 * @group: group number to check
766 *
767 * Return the number of blocks used by the group descriptor table
768 * (primary or backup) in this group. In the future there may be a
769 * different number of descriptor blocks in each group.
770 */
771unsigned long ext4_bg_num_gdb(struct super_block *sb, ext4_group_t group)
772{
773 unsigned long first_meta_bg =
774 le32_to_cpu(EXT4_SB(sb)->s_es->s_first_meta_bg);
775 unsigned long metagroup = group / EXT4_DESC_PER_BLOCK(sb);
776
777 if (!EXT4_HAS_INCOMPAT_FEATURE(sb,EXT4_FEATURE_INCOMPAT_META_BG) ||
778 metagroup < first_meta_bg)
779 return ext4_bg_num_gdb_nometa(sb, group);
780
781 return ext4_bg_num_gdb_meta(sb,group);
782
783}
784
785/*
786 * This function returns the number of file system metadata clusters at
787 * the beginning of a block group, including the reserved gdt blocks.
788 */
789static unsigned ext4_num_base_meta_clusters(struct super_block *sb,
790 ext4_group_t block_group)
791{
792 struct ext4_sb_info *sbi = EXT4_SB(sb);
793 unsigned num;
794
795 /* Check for superblock and gdt backups in this group */
796 num = ext4_bg_has_super(sb, block_group);
797
798 if (!EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_META_BG) ||
799 block_group < le32_to_cpu(sbi->s_es->s_first_meta_bg) *
800 sbi->s_desc_per_block) {
801 if (num) {
802 num += ext4_bg_num_gdb(sb, block_group);
803 num += le16_to_cpu(sbi->s_es->s_reserved_gdt_blocks);
804 }
805 } else { /* For META_BG_BLOCK_GROUPS */
806 num += ext4_bg_num_gdb(sb, block_group);
807 }
808 return EXT4_NUM_B2C(sbi, num);
809}
810/**
811 * ext4_inode_to_goal_block - return a hint for block allocation
812 * @inode: inode for block allocation
813 *
814 * Return the ideal location to start allocating blocks for a
815 * newly created inode.
816 */
817ext4_fsblk_t ext4_inode_to_goal_block(struct inode *inode)
818{
819 struct ext4_inode_info *ei = EXT4_I(inode);
820 ext4_group_t block_group;
821 ext4_grpblk_t colour;
822 int flex_size = ext4_flex_bg_size(EXT4_SB(inode->i_sb));
823 ext4_fsblk_t bg_start;
824 ext4_fsblk_t last_block;
825
826 block_group = ei->i_block_group;
827 if (flex_size >= EXT4_FLEX_SIZE_DIR_ALLOC_SCHEME) {
828 /*
829 * If there are at least EXT4_FLEX_SIZE_DIR_ALLOC_SCHEME
830 * block groups per flexgroup, reserve the first block
831 * group for directories and special files. Regular
832 * files will start at the second block group. This
833 * tends to speed up directory access and improves
834 * fsck times.
835 */
836 block_group &= ~(flex_size-1);
837 if (S_ISREG(inode->i_mode))
838 block_group++;
839 }
840 bg_start = ext4_group_first_block_no(inode->i_sb, block_group);
841 last_block = ext4_blocks_count(EXT4_SB(inode->i_sb)->s_es) - 1;
842
843 /*
844 * If we are doing delayed allocation, we don't need take
845 * colour into account.
846 */
847 if (test_opt(inode->i_sb, DELALLOC))
848 return bg_start;
849
850 if (bg_start + EXT4_BLOCKS_PER_GROUP(inode->i_sb) <= last_block)
851 colour = (current->pid % 16) *
852 (EXT4_BLOCKS_PER_GROUP(inode->i_sb) / 16);
853 else
854 colour = (current->pid % 16) * ((last_block - bg_start) / 16);
855 return bg_start + colour;
856}
857