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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/quotaops.h>
18#include <linux/buffer_head.h>
19#include "ext4.h"
20#include "ext4_jbd2.h"
21#include "mballoc.h"
22
23#include <trace/events/ext4.h>
24
25static unsigned ext4_num_base_meta_clusters(struct super_block *sb,
26 ext4_group_t block_group);
27/*
28 * balloc.c contains the blocks allocation and deallocation routines
29 */
30
31/*
32 * Calculate block group number for a given block number
33 */
34ext4_group_t ext4_get_group_number(struct super_block *sb,
35 ext4_fsblk_t block)
36{
37 ext4_group_t group;
38
39 if (test_opt2(sb, STD_GROUP_SIZE))
40 group = (block -
41 le32_to_cpu(EXT4_SB(sb)->s_es->s_first_data_block)) >>
42 (EXT4_BLOCK_SIZE_BITS(sb) + EXT4_CLUSTER_BITS(sb) + 3);
43 else
44 ext4_get_group_no_and_offset(sb, block, &group, NULL);
45 return group;
46}
47
48/*
49 * Calculate the block group number and offset into the block/cluster
50 * allocation bitmap, given a block number
51 */
52void ext4_get_group_no_and_offset(struct super_block *sb, ext4_fsblk_t blocknr,
53 ext4_group_t *blockgrpp, ext4_grpblk_t *offsetp)
54{
55 struct ext4_super_block *es = EXT4_SB(sb)->s_es;
56 ext4_grpblk_t offset;
57
58 blocknr = blocknr - le32_to_cpu(es->s_first_data_block);
59 offset = do_div(blocknr, EXT4_BLOCKS_PER_GROUP(sb)) >>
60 EXT4_SB(sb)->s_cluster_bits;
61 if (offsetp)
62 *offsetp = offset;
63 if (blockgrpp)
64 *blockgrpp = blocknr;
65
66}
67
68/*
69 * Check whether the 'block' lives within the 'block_group'. Returns 1 if so
70 * and 0 otherwise.
71 */
72static inline int ext4_block_in_group(struct super_block *sb,
73 ext4_fsblk_t block,
74 ext4_group_t block_group)
75{
76 ext4_group_t actual_group;
77
78 actual_group = ext4_get_group_number(sb, block);
79 return (actual_group == block_group) ? 1 : 0;
80}
81
82/* Return the number of clusters used for file system metadata; this
83 * represents the overhead needed by the file system.
84 */
85static unsigned ext4_num_overhead_clusters(struct super_block *sb,
86 ext4_group_t block_group,
87 struct ext4_group_desc *gdp)
88{
89 unsigned num_clusters;
90 int block_cluster = -1, inode_cluster = -1, itbl_cluster = -1, i, c;
91 ext4_fsblk_t start = ext4_group_first_block_no(sb, block_group);
92 ext4_fsblk_t itbl_blk;
93 struct ext4_sb_info *sbi = EXT4_SB(sb);
94
95 /* This is the number of clusters used by the superblock,
96 * block group descriptors, and reserved block group
97 * descriptor blocks */
98 num_clusters = ext4_num_base_meta_clusters(sb, block_group);
99
100 /*
101 * For the allocation bitmaps and inode table, we first need
102 * to check to see if the block is in the block group. If it
103 * is, then check to see if the cluster is already accounted
104 * for in the clusters used for the base metadata cluster, or
105 * if we can increment the base metadata cluster to include
106 * that block. Otherwise, we will have to track the cluster
107 * used for the allocation bitmap or inode table explicitly.
108 * Normally all of these blocks are contiguous, so the special
109 * case handling shouldn't be necessary except for *very*
110 * unusual file system layouts.
111 */
112 if (ext4_block_in_group(sb, ext4_block_bitmap(sb, gdp), block_group)) {
113 block_cluster = EXT4_B2C(sbi,
114 ext4_block_bitmap(sb, gdp) - start);
115 if (block_cluster < num_clusters)
116 block_cluster = -1;
117 else if (block_cluster == num_clusters) {
118 num_clusters++;
119 block_cluster = -1;
120 }
121 }
122
123 if (ext4_block_in_group(sb, ext4_inode_bitmap(sb, gdp), block_group)) {
124 inode_cluster = EXT4_B2C(sbi,
125 ext4_inode_bitmap(sb, gdp) - start);
126 if (inode_cluster < num_clusters)
127 inode_cluster = -1;
128 else if (inode_cluster == num_clusters) {
129 num_clusters++;
130 inode_cluster = -1;
131 }
132 }
133
134 itbl_blk = ext4_inode_table(sb, gdp);
135 for (i = 0; i < sbi->s_itb_per_group; i++) {
136 if (ext4_block_in_group(sb, itbl_blk + i, block_group)) {
137 c = EXT4_B2C(sbi, itbl_blk + i - start);
138 if ((c < num_clusters) || (c == inode_cluster) ||
139 (c == block_cluster) || (c == itbl_cluster))
140 continue;
141 if (c == num_clusters) {
142 num_clusters++;
143 continue;
144 }
145 num_clusters++;
146 itbl_cluster = c;
147 }
148 }
149
150 if (block_cluster != -1)
151 num_clusters++;
152 if (inode_cluster != -1)
153 num_clusters++;
154
155 return num_clusters;
156}
157
158static unsigned int num_clusters_in_group(struct super_block *sb,
159 ext4_group_t block_group)
160{
161 unsigned int blocks;
162
163 if (block_group == ext4_get_groups_count(sb) - 1) {
164 /*
165 * Even though mke2fs always initializes the first and
166 * last group, just in case some other tool was used,
167 * we need to make sure we calculate the right free
168 * blocks.
169 */
170 blocks = ext4_blocks_count(EXT4_SB(sb)->s_es) -
171 ext4_group_first_block_no(sb, block_group);
172 } else
173 blocks = EXT4_BLOCKS_PER_GROUP(sb);
174 return EXT4_NUM_B2C(EXT4_SB(sb), blocks);
175}
176
177/* Initializes an uninitialized block bitmap */
178static int ext4_init_block_bitmap(struct super_block *sb,
179 struct buffer_head *bh,
180 ext4_group_t block_group,
181 struct ext4_group_desc *gdp)
182{
183 unsigned int bit, bit_max;
184 struct ext4_sb_info *sbi = EXT4_SB(sb);
185 ext4_fsblk_t start, tmp;
186 int flex_bg = 0;
187 struct ext4_group_info *grp;
188
189 J_ASSERT_BH(bh, buffer_locked(bh));
190
191 /* If checksum is bad mark all blocks used to prevent allocation
192 * essentially implementing a per-group read-only flag. */
193 if (!ext4_group_desc_csum_verify(sb, block_group, gdp)) {
194 grp = ext4_get_group_info(sb, block_group);
195 if (!EXT4_MB_GRP_BBITMAP_CORRUPT(grp))
196 percpu_counter_sub(&sbi->s_freeclusters_counter,
197 grp->bb_free);
198 set_bit(EXT4_GROUP_INFO_BBITMAP_CORRUPT_BIT, &grp->bb_state);
199 if (!EXT4_MB_GRP_IBITMAP_CORRUPT(grp)) {
200 int count;
201 count = ext4_free_inodes_count(sb, gdp);
202 percpu_counter_sub(&sbi->s_freeinodes_counter,
203 count);
204 }
205 set_bit(EXT4_GROUP_INFO_IBITMAP_CORRUPT_BIT, &grp->bb_state);
206 return -EFSBADCRC;
207 }
208 memset(bh->b_data, 0, sb->s_blocksize);
209
210 bit_max = ext4_num_base_meta_clusters(sb, block_group);
211 for (bit = 0; bit < bit_max; bit++)
212 ext4_set_bit(bit, bh->b_data);
213
214 start = ext4_group_first_block_no(sb, block_group);
215
216 if (ext4_has_feature_flex_bg(sb))
217 flex_bg = 1;
218
219 /* Set bits for block and inode bitmaps, and inode table */
220 tmp = ext4_block_bitmap(sb, gdp);
221 if (!flex_bg || ext4_block_in_group(sb, tmp, block_group))
222 ext4_set_bit(EXT4_B2C(sbi, tmp - start), bh->b_data);
223
224 tmp = ext4_inode_bitmap(sb, gdp);
225 if (!flex_bg || ext4_block_in_group(sb, tmp, block_group))
226 ext4_set_bit(EXT4_B2C(sbi, tmp - start), bh->b_data);
227
228 tmp = ext4_inode_table(sb, gdp);
229 for (; tmp < ext4_inode_table(sb, gdp) +
230 sbi->s_itb_per_group; tmp++) {
231 if (!flex_bg || ext4_block_in_group(sb, tmp, block_group))
232 ext4_set_bit(EXT4_B2C(sbi, tmp - start), bh->b_data);
233 }
234
235 /*
236 * Also if the number of blocks within the group is less than
237 * the blocksize * 8 ( which is the size of bitmap ), set rest
238 * of the block bitmap to 1
239 */
240 ext4_mark_bitmap_end(num_clusters_in_group(sb, block_group),
241 sb->s_blocksize * 8, bh->b_data);
242 ext4_block_bitmap_csum_set(sb, block_group, gdp, bh);
243 ext4_group_desc_csum_set(sb, block_group, gdp);
244 return 0;
245}
246
247/* Return the number of free blocks in a block group. It is used when
248 * the block bitmap is uninitialized, so we can't just count the bits
249 * in the bitmap. */
250unsigned ext4_free_clusters_after_init(struct super_block *sb,
251 ext4_group_t block_group,
252 struct ext4_group_desc *gdp)
253{
254 return num_clusters_in_group(sb, block_group) -
255 ext4_num_overhead_clusters(sb, block_group, gdp);
256}
257
258/*
259 * The free blocks are managed by bitmaps. A file system contains several
260 * blocks groups. Each group contains 1 bitmap block for blocks, 1 bitmap
261 * block for inodes, N blocks for the inode table and data blocks.
262 *
263 * The file system contains group descriptors which are located after the
264 * super block. Each descriptor contains the number of the bitmap block and
265 * the free blocks count in the block. The descriptors are loaded in memory
266 * when a file system is mounted (see ext4_fill_super).
267 */
268
269/**
270 * ext4_get_group_desc() -- load group descriptor from disk
271 * @sb: super block
272 * @block_group: given block group
273 * @bh: pointer to the buffer head to store the block
274 * group descriptor
275 */
276struct ext4_group_desc * ext4_get_group_desc(struct super_block *sb,
277 ext4_group_t block_group,
278 struct buffer_head **bh)
279{
280 unsigned int group_desc;
281 unsigned int offset;
282 ext4_group_t ngroups = ext4_get_groups_count(sb);
283 struct ext4_group_desc *desc;
284 struct ext4_sb_info *sbi = EXT4_SB(sb);
285
286 if (block_group >= ngroups) {
287 ext4_error(sb, "block_group >= groups_count - block_group = %u,"
288 " groups_count = %u", block_group, ngroups);
289
290 return NULL;
291 }
292
293 group_desc = block_group >> EXT4_DESC_PER_BLOCK_BITS(sb);
294 offset = block_group & (EXT4_DESC_PER_BLOCK(sb) - 1);
295 if (!sbi->s_group_desc[group_desc]) {
296 ext4_error(sb, "Group descriptor not loaded - "
297 "block_group = %u, group_desc = %u, desc = %u",
298 block_group, group_desc, offset);
299 return NULL;
300 }
301
302 desc = (struct ext4_group_desc *)(
303 (__u8 *)sbi->s_group_desc[group_desc]->b_data +
304 offset * EXT4_DESC_SIZE(sb));
305 if (bh)
306 *bh = sbi->s_group_desc[group_desc];
307 return desc;
308}
309
310/*
311 * Return the block number which was discovered to be invalid, or 0 if
312 * the block bitmap is valid.
313 */
314static ext4_fsblk_t ext4_valid_block_bitmap(struct super_block *sb,
315 struct ext4_group_desc *desc,
316 ext4_group_t block_group,
317 struct buffer_head *bh)
318{
319 struct ext4_sb_info *sbi = EXT4_SB(sb);
320 ext4_grpblk_t offset;
321 ext4_grpblk_t next_zero_bit;
322 ext4_fsblk_t blk;
323 ext4_fsblk_t group_first_block;
324
325 if (ext4_has_feature_flex_bg(sb)) {
326 /* with FLEX_BG, the inode/block bitmaps and itable
327 * blocks may not be in the group at all
328 * so the bitmap validation will be skipped for those groups
329 * or it has to also read the block group where the bitmaps
330 * are located to verify they are set.
331 */
332 return 0;
333 }
334 group_first_block = ext4_group_first_block_no(sb, block_group);
335
336 /* check whether block bitmap block number is set */
337 blk = ext4_block_bitmap(sb, desc);
338 offset = blk - group_first_block;
339 if (!ext4_test_bit(EXT4_B2C(sbi, offset), bh->b_data))
340 /* bad block bitmap */
341 return blk;
342
343 /* check whether the inode bitmap block number is set */
344 blk = ext4_inode_bitmap(sb, desc);
345 offset = blk - group_first_block;
346 if (!ext4_test_bit(EXT4_B2C(sbi, offset), bh->b_data))
347 /* bad block bitmap */
348 return blk;
349
350 /* check whether the inode table block number is set */
351 blk = ext4_inode_table(sb, desc);
352 offset = blk - group_first_block;
353 next_zero_bit = ext4_find_next_zero_bit(bh->b_data,
354 EXT4_B2C(sbi, offset + EXT4_SB(sb)->s_itb_per_group),
355 EXT4_B2C(sbi, offset));
356 if (next_zero_bit <
357 EXT4_B2C(sbi, offset + EXT4_SB(sb)->s_itb_per_group))
358 /* bad bitmap for inode tables */
359 return blk;
360 return 0;
361}
362
363static int ext4_validate_block_bitmap(struct super_block *sb,
364 struct ext4_group_desc *desc,
365 ext4_group_t block_group,
366 struct buffer_head *bh)
367{
368 ext4_fsblk_t blk;
369 struct ext4_group_info *grp = ext4_get_group_info(sb, block_group);
370 struct ext4_sb_info *sbi = EXT4_SB(sb);
371
372 if (buffer_verified(bh))
373 return 0;
374 if (EXT4_MB_GRP_BBITMAP_CORRUPT(grp))
375 return -EFSCORRUPTED;
376
377 ext4_lock_group(sb, block_group);
378 if (unlikely(!ext4_block_bitmap_csum_verify(sb, block_group,
379 desc, bh))) {
380 ext4_unlock_group(sb, block_group);
381 ext4_error(sb, "bg %u: bad block bitmap checksum", block_group);
382 if (!EXT4_MB_GRP_BBITMAP_CORRUPT(grp))
383 percpu_counter_sub(&sbi->s_freeclusters_counter,
384 grp->bb_free);
385 set_bit(EXT4_GROUP_INFO_BBITMAP_CORRUPT_BIT, &grp->bb_state);
386 return -EFSBADCRC;
387 }
388 blk = ext4_valid_block_bitmap(sb, desc, block_group, bh);
389 if (unlikely(blk != 0)) {
390 ext4_unlock_group(sb, block_group);
391 ext4_error(sb, "bg %u: block %llu: invalid block bitmap",
392 block_group, blk);
393 if (!EXT4_MB_GRP_BBITMAP_CORRUPT(grp))
394 percpu_counter_sub(&sbi->s_freeclusters_counter,
395 grp->bb_free);
396 set_bit(EXT4_GROUP_INFO_BBITMAP_CORRUPT_BIT, &grp->bb_state);
397 return -EFSCORRUPTED;
398 }
399 set_buffer_verified(bh);
400 ext4_unlock_group(sb, block_group);
401 return 0;
402}
403
404/**
405 * ext4_read_block_bitmap_nowait()
406 * @sb: super block
407 * @block_group: given block group
408 *
409 * Read the bitmap for a given block_group,and validate the
410 * bits for block/inode/inode tables are set in the bitmaps
411 *
412 * Return buffer_head on success or NULL in case of failure.
413 */
414struct buffer_head *
415ext4_read_block_bitmap_nowait(struct super_block *sb, ext4_group_t block_group)
416{
417 struct ext4_group_desc *desc;
418 struct buffer_head *bh;
419 ext4_fsblk_t bitmap_blk;
420 int err;
421
422 desc = ext4_get_group_desc(sb, block_group, NULL);
423 if (!desc)
424 return ERR_PTR(-EFSCORRUPTED);
425 bitmap_blk = ext4_block_bitmap(sb, desc);
426 bh = sb_getblk(sb, bitmap_blk);
427 if (unlikely(!bh)) {
428 ext4_error(sb, "Cannot get buffer for block bitmap - "
429 "block_group = %u, block_bitmap = %llu",
430 block_group, bitmap_blk);
431 return ERR_PTR(-ENOMEM);
432 }
433
434 if (bitmap_uptodate(bh))
435 goto verify;
436
437 lock_buffer(bh);
438 if (bitmap_uptodate(bh)) {
439 unlock_buffer(bh);
440 goto verify;
441 }
442 ext4_lock_group(sb, block_group);
443 if (desc->bg_flags & cpu_to_le16(EXT4_BG_BLOCK_UNINIT)) {
444 err = ext4_init_block_bitmap(sb, bh, block_group, desc);
445 set_bitmap_uptodate(bh);
446 set_buffer_uptodate(bh);
447 ext4_unlock_group(sb, block_group);
448 unlock_buffer(bh);
449 if (err) {
450 ext4_error(sb, "Failed to init block bitmap for group "
451 "%u: %d", block_group, err);
452 goto out;
453 }
454 goto verify;
455 }
456 ext4_unlock_group(sb, block_group);
457 if (buffer_uptodate(bh)) {
458 /*
459 * if not uninit if bh is uptodate,
460 * bitmap is also uptodate
461 */
462 set_bitmap_uptodate(bh);
463 unlock_buffer(bh);
464 goto verify;
465 }
466 /*
467 * submit the buffer_head for reading
468 */
469 set_buffer_new(bh);
470 trace_ext4_read_block_bitmap_load(sb, block_group);
471 bh->b_end_io = ext4_end_bitmap_read;
472 get_bh(bh);
473 submit_bh(READ | REQ_META | REQ_PRIO, bh);
474 return bh;
475verify:
476 err = ext4_validate_block_bitmap(sb, desc, block_group, bh);
477 if (err)
478 goto out;
479 return bh;
480out:
481 put_bh(bh);
482 return ERR_PTR(err);
483}
484
485/* Returns 0 on success, 1 on error */
486int ext4_wait_block_bitmap(struct super_block *sb, ext4_group_t block_group,
487 struct buffer_head *bh)
488{
489 struct ext4_group_desc *desc;
490
491 if (!buffer_new(bh))
492 return 0;
493 desc = ext4_get_group_desc(sb, block_group, NULL);
494 if (!desc)
495 return -EFSCORRUPTED;
496 wait_on_buffer(bh);
497 if (!buffer_uptodate(bh)) {
498 ext4_error(sb, "Cannot read block bitmap - "
499 "block_group = %u, block_bitmap = %llu",
500 block_group, (unsigned long long) bh->b_blocknr);
501 return -EIO;
502 }
503 clear_buffer_new(bh);
504 /* Panic or remount fs read-only if block bitmap is invalid */
505 return ext4_validate_block_bitmap(sb, desc, block_group, bh);
506}
507
508struct buffer_head *
509ext4_read_block_bitmap(struct super_block *sb, ext4_group_t block_group)
510{
511 struct buffer_head *bh;
512 int err;
513
514 bh = ext4_read_block_bitmap_nowait(sb, block_group);
515 if (IS_ERR(bh))
516 return bh;
517 err = ext4_wait_block_bitmap(sb, block_group, bh);
518 if (err) {
519 put_bh(bh);
520 return ERR_PTR(err);
521 }
522 return bh;
523}
524
525/**
526 * ext4_has_free_clusters()
527 * @sbi: in-core super block structure.
528 * @nclusters: number of needed blocks
529 * @flags: flags from ext4_mb_new_blocks()
530 *
531 * Check if filesystem has nclusters free & available for allocation.
532 * On success return 1, return 0 on failure.
533 */
534static int ext4_has_free_clusters(struct ext4_sb_info *sbi,
535 s64 nclusters, unsigned int flags)
536{
537 s64 free_clusters, dirty_clusters, rsv, resv_clusters;
538 struct percpu_counter *fcc = &sbi->s_freeclusters_counter;
539 struct percpu_counter *dcc = &sbi->s_dirtyclusters_counter;
540
541 free_clusters = percpu_counter_read_positive(fcc);
542 dirty_clusters = percpu_counter_read_positive(dcc);
543 resv_clusters = atomic64_read(&sbi->s_resv_clusters);
544
545 /*
546 * r_blocks_count should always be multiple of the cluster ratio so
547 * we are safe to do a plane bit shift only.
548 */
549 rsv = (ext4_r_blocks_count(sbi->s_es) >> sbi->s_cluster_bits) +
550 resv_clusters;
551
552 if (free_clusters - (nclusters + rsv + dirty_clusters) <
553 EXT4_FREECLUSTERS_WATERMARK) {
554 free_clusters = percpu_counter_sum_positive(fcc);
555 dirty_clusters = percpu_counter_sum_positive(dcc);
556 }
557 /* Check whether we have space after accounting for current
558 * dirty clusters & root reserved clusters.
559 */
560 if (free_clusters >= (rsv + nclusters + dirty_clusters))
561 return 1;
562
563 /* Hm, nope. Are (enough) root reserved clusters available? */
564 if (uid_eq(sbi->s_resuid, current_fsuid()) ||
565 (!gid_eq(sbi->s_resgid, GLOBAL_ROOT_GID) && in_group_p(sbi->s_resgid)) ||
566 capable(CAP_SYS_RESOURCE) ||
567 (flags & EXT4_MB_USE_ROOT_BLOCKS)) {
568
569 if (free_clusters >= (nclusters + dirty_clusters +
570 resv_clusters))
571 return 1;
572 }
573 /* No free blocks. Let's see if we can dip into reserved pool */
574 if (flags & EXT4_MB_USE_RESERVED) {
575 if (free_clusters >= (nclusters + dirty_clusters))
576 return 1;
577 }
578
579 return 0;
580}
581
582int ext4_claim_free_clusters(struct ext4_sb_info *sbi,
583 s64 nclusters, unsigned int flags)
584{
585 if (ext4_has_free_clusters(sbi, nclusters, flags)) {
586 percpu_counter_add(&sbi->s_dirtyclusters_counter, nclusters);
587 return 0;
588 } else
589 return -ENOSPC;
590}
591
592/**
593 * ext4_should_retry_alloc()
594 * @sb: super block
595 * @retries number of attemps has been made
596 *
597 * ext4_should_retry_alloc() is called when ENOSPC is returned, and if
598 * it is profitable to retry the operation, this function will wait
599 * for the current or committing transaction to complete, and then
600 * return TRUE.
601 *
602 * if the total number of retries exceed three times, return FALSE.
603 */
604int ext4_should_retry_alloc(struct super_block *sb, int *retries)
605{
606 if (!ext4_has_free_clusters(EXT4_SB(sb), 1, 0) ||
607 (*retries)++ > 3 ||
608 !EXT4_SB(sb)->s_journal)
609 return 0;
610
611 jbd_debug(1, "%s: retrying operation after ENOSPC\n", sb->s_id);
612
613 return jbd2_journal_force_commit_nested(EXT4_SB(sb)->s_journal);
614}
615
616/*
617 * ext4_new_meta_blocks() -- allocate block for meta data (indexing) blocks
618 *
619 * @handle: handle to this transaction
620 * @inode: file inode
621 * @goal: given target block(filesystem wide)
622 * @count: pointer to total number of clusters needed
623 * @errp: error code
624 *
625 * Return 1st allocated block number on success, *count stores total account
626 * error stores in errp pointer
627 */
628ext4_fsblk_t ext4_new_meta_blocks(handle_t *handle, struct inode *inode,
629 ext4_fsblk_t goal, unsigned int flags,
630 unsigned long *count, int *errp)
631{
632 struct ext4_allocation_request ar;
633 ext4_fsblk_t ret;
634
635 memset(&ar, 0, sizeof(ar));
636 /* Fill with neighbour allocated blocks */
637 ar.inode = inode;
638 ar.goal = goal;
639 ar.len = count ? *count : 1;
640 ar.flags = flags;
641
642 ret = ext4_mb_new_blocks(handle, &ar, errp);
643 if (count)
644 *count = ar.len;
645 /*
646 * Account for the allocated meta blocks. We will never
647 * fail EDQUOT for metdata, but we do account for it.
648 */
649 if (!(*errp) && (flags & EXT4_MB_DELALLOC_RESERVED)) {
650 dquot_alloc_block_nofail(inode,
651 EXT4_C2B(EXT4_SB(inode->i_sb), ar.len));
652 }
653 return ret;
654}
655
656/**
657 * ext4_count_free_clusters() -- count filesystem free clusters
658 * @sb: superblock
659 *
660 * Adds up the number of free clusters from each block group.
661 */
662ext4_fsblk_t ext4_count_free_clusters(struct super_block *sb)
663{
664 ext4_fsblk_t desc_count;
665 struct ext4_group_desc *gdp;
666 ext4_group_t i;
667 ext4_group_t ngroups = ext4_get_groups_count(sb);
668 struct ext4_group_info *grp;
669#ifdef EXT4FS_DEBUG
670 struct ext4_super_block *es;
671 ext4_fsblk_t bitmap_count;
672 unsigned int x;
673 struct buffer_head *bitmap_bh = NULL;
674
675 es = EXT4_SB(sb)->s_es;
676 desc_count = 0;
677 bitmap_count = 0;
678 gdp = NULL;
679
680 for (i = 0; i < ngroups; i++) {
681 gdp = ext4_get_group_desc(sb, i, NULL);
682 if (!gdp)
683 continue;
684 grp = NULL;
685 if (EXT4_SB(sb)->s_group_info)
686 grp = ext4_get_group_info(sb, i);
687 if (!grp || !EXT4_MB_GRP_BBITMAP_CORRUPT(grp))
688 desc_count += ext4_free_group_clusters(sb, gdp);
689 brelse(bitmap_bh);
690 bitmap_bh = ext4_read_block_bitmap(sb, i);
691 if (IS_ERR(bitmap_bh)) {
692 bitmap_bh = NULL;
693 continue;
694 }
695
696 x = ext4_count_free(bitmap_bh->b_data,
697 EXT4_CLUSTERS_PER_GROUP(sb) / 8);
698 printk(KERN_DEBUG "group %u: stored = %d, counted = %u\n",
699 i, ext4_free_group_clusters(sb, gdp), x);
700 bitmap_count += x;
701 }
702 brelse(bitmap_bh);
703 printk(KERN_DEBUG "ext4_count_free_clusters: stored = %llu"
704 ", computed = %llu, %llu\n",
705 EXT4_NUM_B2C(EXT4_SB(sb), ext4_free_blocks_count(es)),
706 desc_count, bitmap_count);
707 return bitmap_count;
708#else
709 desc_count = 0;
710 for (i = 0; i < ngroups; i++) {
711 gdp = ext4_get_group_desc(sb, i, NULL);
712 if (!gdp)
713 continue;
714 grp = NULL;
715 if (EXT4_SB(sb)->s_group_info)
716 grp = ext4_get_group_info(sb, i);
717 if (!grp || !EXT4_MB_GRP_BBITMAP_CORRUPT(grp))
718 desc_count += ext4_free_group_clusters(sb, gdp);
719 }
720
721 return desc_count;
722#endif
723}
724
725static inline int test_root(ext4_group_t a, int b)
726{
727 while (1) {
728 if (a < b)
729 return 0;
730 if (a == b)
731 return 1;
732 if ((a % b) != 0)
733 return 0;
734 a = a / b;
735 }
736}
737
738/**
739 * ext4_bg_has_super - number of blocks used by the superblock in group
740 * @sb: superblock for filesystem
741 * @group: group number to check
742 *
743 * Return the number of blocks used by the superblock (primary or backup)
744 * in this group. Currently this will be only 0 or 1.
745 */
746int ext4_bg_has_super(struct super_block *sb, ext4_group_t group)
747{
748 struct ext4_super_block *es = EXT4_SB(sb)->s_es;
749
750 if (group == 0)
751 return 1;
752 if (ext4_has_feature_sparse_super2(sb)) {
753 if (group == le32_to_cpu(es->s_backup_bgs[0]) ||
754 group == le32_to_cpu(es->s_backup_bgs[1]))
755 return 1;
756 return 0;
757 }
758 if ((group <= 1) || !ext4_has_feature_sparse_super(sb))
759 return 1;
760 if (!(group & 1))
761 return 0;
762 if (test_root(group, 3) || (test_root(group, 5)) ||
763 test_root(group, 7))
764 return 1;
765
766 return 0;
767}
768
769static unsigned long ext4_bg_num_gdb_meta(struct super_block *sb,
770 ext4_group_t group)
771{
772 unsigned long metagroup = group / EXT4_DESC_PER_BLOCK(sb);
773 ext4_group_t first = metagroup * EXT4_DESC_PER_BLOCK(sb);
774 ext4_group_t last = first + EXT4_DESC_PER_BLOCK(sb) - 1;
775
776 if (group == first || group == first + 1 || group == last)
777 return 1;
778 return 0;
779}
780
781static unsigned long ext4_bg_num_gdb_nometa(struct super_block *sb,
782 ext4_group_t group)
783{
784 if (!ext4_bg_has_super(sb, group))
785 return 0;
786
787 if (ext4_has_feature_meta_bg(sb))
788 return le32_to_cpu(EXT4_SB(sb)->s_es->s_first_meta_bg);
789 else
790 return EXT4_SB(sb)->s_gdb_count;
791}
792
793/**
794 * ext4_bg_num_gdb - number of blocks used by the group table in group
795 * @sb: superblock for filesystem
796 * @group: group number to check
797 *
798 * Return the number of blocks used by the group descriptor table
799 * (primary or backup) in this group. In the future there may be a
800 * different number of descriptor blocks in each group.
801 */
802unsigned long ext4_bg_num_gdb(struct super_block *sb, ext4_group_t group)
803{
804 unsigned long first_meta_bg =
805 le32_to_cpu(EXT4_SB(sb)->s_es->s_first_meta_bg);
806 unsigned long metagroup = group / EXT4_DESC_PER_BLOCK(sb);
807
808 if (!ext4_has_feature_meta_bg(sb) || metagroup < first_meta_bg)
809 return ext4_bg_num_gdb_nometa(sb, group);
810
811 return ext4_bg_num_gdb_meta(sb,group);
812
813}
814
815/*
816 * This function returns the number of file system metadata clusters at
817 * the beginning of a block group, including the reserved gdt blocks.
818 */
819static unsigned ext4_num_base_meta_clusters(struct super_block *sb,
820 ext4_group_t block_group)
821{
822 struct ext4_sb_info *sbi = EXT4_SB(sb);
823 unsigned num;
824
825 /* Check for superblock and gdt backups in this group */
826 num = ext4_bg_has_super(sb, block_group);
827
828 if (!ext4_has_feature_meta_bg(sb) ||
829 block_group < le32_to_cpu(sbi->s_es->s_first_meta_bg) *
830 sbi->s_desc_per_block) {
831 if (num) {
832 num += ext4_bg_num_gdb(sb, block_group);
833 num += le16_to_cpu(sbi->s_es->s_reserved_gdt_blocks);
834 }
835 } else { /* For META_BG_BLOCK_GROUPS */
836 num += ext4_bg_num_gdb(sb, block_group);
837 }
838 return EXT4_NUM_B2C(sbi, num);
839}
840/**
841 * ext4_inode_to_goal_block - return a hint for block allocation
842 * @inode: inode for block allocation
843 *
844 * Return the ideal location to start allocating blocks for a
845 * newly created inode.
846 */
847ext4_fsblk_t ext4_inode_to_goal_block(struct inode *inode)
848{
849 struct ext4_inode_info *ei = EXT4_I(inode);
850 ext4_group_t block_group;
851 ext4_grpblk_t colour;
852 int flex_size = ext4_flex_bg_size(EXT4_SB(inode->i_sb));
853 ext4_fsblk_t bg_start;
854 ext4_fsblk_t last_block;
855
856 block_group = ei->i_block_group;
857 if (flex_size >= EXT4_FLEX_SIZE_DIR_ALLOC_SCHEME) {
858 /*
859 * If there are at least EXT4_FLEX_SIZE_DIR_ALLOC_SCHEME
860 * block groups per flexgroup, reserve the first block
861 * group for directories and special files. Regular
862 * files will start at the second block group. This
863 * tends to speed up directory access and improves
864 * fsck times.
865 */
866 block_group &= ~(flex_size-1);
867 if (S_ISREG(inode->i_mode))
868 block_group++;
869 }
870 bg_start = ext4_group_first_block_no(inode->i_sb, block_group);
871 last_block = ext4_blocks_count(EXT4_SB(inode->i_sb)->s_es) - 1;
872
873 /*
874 * If we are doing delayed allocation, we don't need take
875 * colour into account.
876 */
877 if (test_opt(inode->i_sb, DELALLOC))
878 return bg_start;
879
880 if (bg_start + EXT4_BLOCKS_PER_GROUP(inode->i_sb) <= last_block)
881 colour = (current->pid % 16) *
882 (EXT4_BLOCKS_PER_GROUP(inode->i_sb) / 16);
883 else
884 colour = (current->pid % 16) * ((last_block - bg_start) / 16);
885 return bg_start + colour;
886}
887
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