1 // SPDX-License-Identifier: GPL-2.0
3 * linux/fs/ext4/balloc.c
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)
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
15 #include <linux/time.h>
16 #include <linux/capability.h>
18 #include <linux/quotaops.h>
19 #include <linux/buffer_head.h>
21 #include "ext4_jbd2.h"
24 #include <trace/events/ext4.h>
26 static unsigned ext4_num_base_meta_clusters(struct super_block *sb,
27 ext4_group_t block_group);
29 * balloc.c contains the blocks allocation and deallocation routines
33 * Calculate block group number for a given block number
35 ext4_group_t ext4_get_group_number(struct super_block *sb,
40 if (test_opt2(sb, STD_GROUP_SIZE))
42 le32_to_cpu(EXT4_SB(sb)->s_es->s_first_data_block)) >>
43 (EXT4_BLOCK_SIZE_BITS(sb) + EXT4_CLUSTER_BITS(sb) + 3);
45 ext4_get_group_no_and_offset(sb, block, &group, NULL);
50 * Calculate the block group number and offset into the block/cluster
51 * allocation bitmap, given a block number
53 void ext4_get_group_no_and_offset(struct super_block *sb, ext4_fsblk_t blocknr,
54 ext4_group_t *blockgrpp, ext4_grpblk_t *offsetp)
56 struct ext4_super_block *es = EXT4_SB(sb)->s_es;
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;
70 * Check whether the 'block' lives within the 'block_group'. Returns 1 if so
73 static inline int ext4_block_in_group(struct super_block *sb,
75 ext4_group_t block_group)
77 ext4_group_t actual_group;
79 actual_group = ext4_get_group_number(sb, block);
80 return (actual_group == block_group) ? 1 : 0;
83 /* Return the number of clusters used for file system metadata; this
84 * represents the overhead needed by the file system.
86 static unsigned ext4_num_overhead_clusters(struct super_block *sb,
87 ext4_group_t block_group,
88 struct ext4_group_desc *gdp)
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);
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);
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.
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)
118 else if (block_cluster == num_clusters) {
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)
129 else if (inode_cluster == num_clusters) {
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))
142 if (c == num_clusters) {
151 if (block_cluster != -1)
153 if (inode_cluster != -1)
159 static unsigned int num_clusters_in_group(struct super_block *sb,
160 ext4_group_t block_group)
164 if (block_group == ext4_get_groups_count(sb) - 1) {
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
171 blocks = ext4_blocks_count(EXT4_SB(sb)->s_es) -
172 ext4_group_first_block_no(sb, block_group);
174 blocks = EXT4_BLOCKS_PER_GROUP(sb);
175 return EXT4_NUM_B2C(EXT4_SB(sb), blocks);
178 /* Initializes an uninitialized block bitmap */
179 static 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)
184 unsigned int bit, bit_max;
185 struct ext4_sb_info *sbi = EXT4_SB(sb);
186 ext4_fsblk_t start, tmp;
188 J_ASSERT_BH(bh, buffer_locked(bh));
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);
198 memset(bh->b_data, 0, sb->s_blocksize);
200 bit_max = ext4_num_base_meta_clusters(sb, block_group);
201 if ((bit_max >> 3) >= bh->b_size)
202 return -EFSCORRUPTED;
204 for (bit = 0; bit < bit_max; bit++)
205 ext4_set_bit(bit, bh->b_data);
207 start = ext4_group_first_block_no(sb, block_group);
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);
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);
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);
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
230 ext4_mark_bitmap_end(num_clusters_in_group(sb, block_group),
231 sb->s_blocksize * 8, bh->b_data);
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
238 unsigned ext4_free_clusters_after_init(struct super_block *sb,
239 ext4_group_t block_group,
240 struct ext4_group_desc *gdp)
242 return num_clusters_in_group(sb, block_group) -
243 ext4_num_overhead_clusters(sb, block_group, gdp);
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.
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).
258 * ext4_get_group_desc() -- load group descriptor from disk
260 * @block_group: given block group
261 * @bh: pointer to the buffer head to store the block
264 struct ext4_group_desc * ext4_get_group_desc(struct super_block *sb,
265 ext4_group_t block_group,
266 struct buffer_head **bh)
268 unsigned int group_desc;
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;
275 if (block_group >= ngroups) {
276 ext4_error(sb, "block_group >= groups_count - block_group = %u,"
277 " groups_count = %u", block_group, ngroups);
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);
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.
292 ext4_error(sb, "Group descriptor not loaded - "
293 "block_group = %u, group_desc = %u, desc = %u",
294 block_group, group_desc, offset);
298 desc = (struct ext4_group_desc *)(
299 (__u8 *)bh_p->b_data +
300 offset * EXT4_DESC_SIZE(sb));
307 * Return the block number which was discovered to be invalid, or 0 if
308 * the block bitmap is valid.
310 static 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)
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);
320 ext4_fsblk_t group_first_block;
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.
331 group_first_block = ext4_group_first_block_no(sb, block_group);
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 */
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 */
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)
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));
359 EXT4_B2C(sbi, offset + sbi->s_itb_per_group))
360 /* bad bitmap for inode tables */
365 static 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)
371 struct ext4_group_info *grp;
373 if (EXT4_SB(sb)->s_mount_state & EXT4_FC_REPLAY)
376 grp = ext4_get_group_info(sb, block_group);
378 if (buffer_verified(bh))
380 if (EXT4_MB_GRP_BBITMAP_CORRUPT(grp))
381 return -EFSCORRUPTED;
383 ext4_lock_group(sb, block_group);
384 if (buffer_verified(bh))
386 if (unlikely(!ext4_block_bitmap_csum_verify(sb, block_group,
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);
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",
400 ext4_mark_group_bitmap_corrupted(sb, block_group,
401 EXT4_GROUP_INFO_BBITMAP_CORRUPT);
402 return -EFSCORRUPTED;
404 set_buffer_verified(bh);
406 ext4_unlock_group(sb, block_group);
411 * ext4_read_block_bitmap_nowait()
413 * @block_group: given block group
415 * Read the bitmap for a given block_group,and validate the
416 * bits for block/inode/inode tables are set in the bitmaps
418 * Return buffer_head on success or an ERR_PTR in case of failure.
421 ext4_read_block_bitmap_nowait(struct super_block *sb, ext4_group_t block_group,
424 struct ext4_group_desc *desc;
425 struct ext4_sb_info *sbi = EXT4_SB(sb);
426 struct buffer_head *bh;
427 ext4_fsblk_t bitmap_blk;
430 desc = ext4_get_group_desc(sb, block_group, NULL);
432 return ERR_PTR(-EFSCORRUPTED);
433 bitmap_blk = ext4_block_bitmap(sb, desc);
434 if ((bitmap_blk <= le32_to_cpu(sbi->s_es->s_first_data_block)) ||
435 (bitmap_blk >= ext4_blocks_count(sbi->s_es))) {
436 ext4_error(sb, "Invalid block bitmap block %llu in "
437 "block_group %u", bitmap_blk, block_group);
438 ext4_mark_group_bitmap_corrupted(sb, block_group,
439 EXT4_GROUP_INFO_BBITMAP_CORRUPT);
440 return ERR_PTR(-EFSCORRUPTED);
442 bh = sb_getblk(sb, bitmap_blk);
444 ext4_warning(sb, "Cannot get buffer for block bitmap - "
445 "block_group = %u, block_bitmap = %llu",
446 block_group, bitmap_blk);
447 return ERR_PTR(-ENOMEM);
450 if (ignore_locked && buffer_locked(bh)) {
451 /* buffer under IO already, return if called for prefetching */
456 if (bitmap_uptodate(bh))
460 if (bitmap_uptodate(bh)) {
464 ext4_lock_group(sb, block_group);
465 if (ext4_has_group_desc_csum(sb) &&
466 (desc->bg_flags & cpu_to_le16(EXT4_BG_BLOCK_UNINIT))) {
467 if (block_group == 0) {
468 ext4_unlock_group(sb, block_group);
470 ext4_error(sb, "Block bitmap for bg 0 marked "
475 err = ext4_init_block_bitmap(sb, bh, block_group, desc);
476 set_bitmap_uptodate(bh);
477 set_buffer_uptodate(bh);
478 set_buffer_verified(bh);
479 ext4_unlock_group(sb, block_group);
482 ext4_error(sb, "Failed to init block bitmap for group "
483 "%u: %d", block_group, err);
488 ext4_unlock_group(sb, block_group);
489 if (buffer_uptodate(bh)) {
491 * if not uninit if bh is uptodate,
492 * bitmap is also uptodate
494 set_bitmap_uptodate(bh);
499 * submit the buffer_head for reading
502 trace_ext4_read_block_bitmap_load(sb, block_group, ignore_locked);
503 ext4_read_bh_nowait(bh, REQ_META | REQ_PRIO |
504 (ignore_locked ? REQ_RAHEAD : 0),
505 ext4_end_bitmap_read);
508 err = ext4_validate_block_bitmap(sb, desc, block_group, bh);
517 /* Returns 0 on success, -errno on error */
518 int ext4_wait_block_bitmap(struct super_block *sb, ext4_group_t block_group,
519 struct buffer_head *bh)
521 struct ext4_group_desc *desc;
525 desc = ext4_get_group_desc(sb, block_group, NULL);
527 return -EFSCORRUPTED;
529 ext4_simulate_fail_bh(sb, bh, EXT4_SIM_BBITMAP_EIO);
530 if (!buffer_uptodate(bh)) {
531 ext4_error_err(sb, EIO, "Cannot read block bitmap - "
532 "block_group = %u, block_bitmap = %llu",
533 block_group, (unsigned long long) bh->b_blocknr);
534 ext4_mark_group_bitmap_corrupted(sb, block_group,
535 EXT4_GROUP_INFO_BBITMAP_CORRUPT);
538 clear_buffer_new(bh);
539 /* Panic or remount fs read-only if block bitmap is invalid */
540 return ext4_validate_block_bitmap(sb, desc, block_group, bh);
544 ext4_read_block_bitmap(struct super_block *sb, ext4_group_t block_group)
546 struct buffer_head *bh;
549 bh = ext4_read_block_bitmap_nowait(sb, block_group, false);
552 err = ext4_wait_block_bitmap(sb, block_group, bh);
561 * ext4_has_free_clusters()
562 * @sbi: in-core super block structure.
563 * @nclusters: number of needed blocks
564 * @flags: flags from ext4_mb_new_blocks()
566 * Check if filesystem has nclusters free & available for allocation.
567 * On success return 1, return 0 on failure.
569 static int ext4_has_free_clusters(struct ext4_sb_info *sbi,
570 s64 nclusters, unsigned int flags)
572 s64 free_clusters, dirty_clusters, rsv, resv_clusters;
573 struct percpu_counter *fcc = &sbi->s_freeclusters_counter;
574 struct percpu_counter *dcc = &sbi->s_dirtyclusters_counter;
576 free_clusters = percpu_counter_read_positive(fcc);
577 dirty_clusters = percpu_counter_read_positive(dcc);
578 resv_clusters = atomic64_read(&sbi->s_resv_clusters);
581 * r_blocks_count should always be multiple of the cluster ratio so
582 * we are safe to do a plane bit shift only.
584 rsv = (ext4_r_blocks_count(sbi->s_es) >> sbi->s_cluster_bits) +
587 if (free_clusters - (nclusters + rsv + dirty_clusters) <
588 EXT4_FREECLUSTERS_WATERMARK) {
589 free_clusters = percpu_counter_sum_positive(fcc);
590 dirty_clusters = percpu_counter_sum_positive(dcc);
592 /* Check whether we have space after accounting for current
593 * dirty clusters & root reserved clusters.
595 if (free_clusters >= (rsv + nclusters + dirty_clusters))
598 /* Hm, nope. Are (enough) root reserved clusters available? */
599 if (uid_eq(sbi->s_resuid, current_fsuid()) ||
600 (!gid_eq(sbi->s_resgid, GLOBAL_ROOT_GID) && in_group_p(sbi->s_resgid)) ||
601 capable(CAP_SYS_RESOURCE) ||
602 (flags & EXT4_MB_USE_ROOT_BLOCKS)) {
604 if (free_clusters >= (nclusters + dirty_clusters +
608 /* No free blocks. Let's see if we can dip into reserved pool */
609 if (flags & EXT4_MB_USE_RESERVED) {
610 if (free_clusters >= (nclusters + dirty_clusters))
617 int ext4_claim_free_clusters(struct ext4_sb_info *sbi,
618 s64 nclusters, unsigned int flags)
620 if (ext4_has_free_clusters(sbi, nclusters, flags)) {
621 percpu_counter_add(&sbi->s_dirtyclusters_counter, nclusters);
628 * ext4_should_retry_alloc() - check if a block allocation should be retried
630 * @retries: number of attemps has been made
632 * ext4_should_retry_alloc() is called when ENOSPC is returned, and if
633 * it is profitable to retry the operation, this function will wait
634 * for the current or committing transaction to complete, and then
635 * return TRUE. We will only retry once.
637 int ext4_should_retry_alloc(struct super_block *sb, int *retries)
639 if (!ext4_has_free_clusters(EXT4_SB(sb), 1, 0) ||
641 !EXT4_SB(sb)->s_journal)
645 if (EXT4_SB(sb)->s_mb_free_pending == 0)
648 jbd_debug(1, "%s: retrying operation after ENOSPC\n", sb->s_id);
649 jbd2_journal_force_commit_nested(EXT4_SB(sb)->s_journal);
654 * ext4_new_meta_blocks() -- allocate block for meta data (indexing) blocks
656 * @handle: handle to this transaction
658 * @goal: given target block(filesystem wide)
659 * @count: pointer to total number of clusters needed
662 * Return 1st allocated block number on success, *count stores total account
663 * error stores in errp pointer
665 ext4_fsblk_t ext4_new_meta_blocks(handle_t *handle, struct inode *inode,
666 ext4_fsblk_t goal, unsigned int flags,
667 unsigned long *count, int *errp)
669 struct ext4_allocation_request ar;
672 memset(&ar, 0, sizeof(ar));
673 /* Fill with neighbour allocated blocks */
676 ar.len = count ? *count : 1;
679 ret = ext4_mb_new_blocks(handle, &ar, errp);
683 * Account for the allocated meta blocks. We will never
684 * fail EDQUOT for metdata, but we do account for it.
686 if (!(*errp) && (flags & EXT4_MB_DELALLOC_RESERVED)) {
687 dquot_alloc_block_nofail(inode,
688 EXT4_C2B(EXT4_SB(inode->i_sb), ar.len));
694 * ext4_count_free_clusters() -- count filesystem free clusters
697 * Adds up the number of free clusters from each block group.
699 ext4_fsblk_t ext4_count_free_clusters(struct super_block *sb)
701 ext4_fsblk_t desc_count;
702 struct ext4_group_desc *gdp;
704 ext4_group_t ngroups = ext4_get_groups_count(sb);
705 struct ext4_group_info *grp;
707 struct ext4_super_block *es;
708 ext4_fsblk_t bitmap_count;
710 struct buffer_head *bitmap_bh = NULL;
712 es = EXT4_SB(sb)->s_es;
717 for (i = 0; i < ngroups; i++) {
718 gdp = ext4_get_group_desc(sb, i, NULL);
722 if (EXT4_SB(sb)->s_group_info)
723 grp = ext4_get_group_info(sb, i);
724 if (!grp || !EXT4_MB_GRP_BBITMAP_CORRUPT(grp))
725 desc_count += ext4_free_group_clusters(sb, gdp);
727 bitmap_bh = ext4_read_block_bitmap(sb, i);
728 if (IS_ERR(bitmap_bh)) {
733 x = ext4_count_free(bitmap_bh->b_data,
734 EXT4_CLUSTERS_PER_GROUP(sb) / 8);
735 printk(KERN_DEBUG "group %u: stored = %d, counted = %u\n",
736 i, ext4_free_group_clusters(sb, gdp), x);
740 printk(KERN_DEBUG "ext4_count_free_clusters: stored = %llu"
741 ", computed = %llu, %llu\n",
742 EXT4_NUM_B2C(EXT4_SB(sb), ext4_free_blocks_count(es)),
743 desc_count, bitmap_count);
747 for (i = 0; i < ngroups; i++) {
748 gdp = ext4_get_group_desc(sb, i, NULL);
752 if (EXT4_SB(sb)->s_group_info)
753 grp = ext4_get_group_info(sb, i);
754 if (!grp || !EXT4_MB_GRP_BBITMAP_CORRUPT(grp))
755 desc_count += ext4_free_group_clusters(sb, gdp);
762 static inline int test_root(ext4_group_t a, int b)
776 * ext4_bg_has_super - number of blocks used by the superblock in group
777 * @sb: superblock for filesystem
778 * @group: group number to check
780 * Return the number of blocks used by the superblock (primary or backup)
781 * in this group. Currently this will be only 0 or 1.
783 int ext4_bg_has_super(struct super_block *sb, ext4_group_t group)
785 struct ext4_super_block *es = EXT4_SB(sb)->s_es;
789 if (ext4_has_feature_sparse_super2(sb)) {
790 if (group == le32_to_cpu(es->s_backup_bgs[0]) ||
791 group == le32_to_cpu(es->s_backup_bgs[1]))
795 if ((group <= 1) || !ext4_has_feature_sparse_super(sb))
799 if (test_root(group, 3) || (test_root(group, 5)) ||
806 static unsigned long ext4_bg_num_gdb_meta(struct super_block *sb,
809 unsigned long metagroup = group / EXT4_DESC_PER_BLOCK(sb);
810 ext4_group_t first = metagroup * EXT4_DESC_PER_BLOCK(sb);
811 ext4_group_t last = first + EXT4_DESC_PER_BLOCK(sb) - 1;
813 if (group == first || group == first + 1 || group == last)
818 static unsigned long ext4_bg_num_gdb_nometa(struct super_block *sb,
821 if (!ext4_bg_has_super(sb, group))
824 if (ext4_has_feature_meta_bg(sb))
825 return le32_to_cpu(EXT4_SB(sb)->s_es->s_first_meta_bg);
827 return EXT4_SB(sb)->s_gdb_count;
831 * ext4_bg_num_gdb - number of blocks used by the group table in group
832 * @sb: superblock for filesystem
833 * @group: group number to check
835 * Return the number of blocks used by the group descriptor table
836 * (primary or backup) in this group. In the future there may be a
837 * different number of descriptor blocks in each group.
839 unsigned long ext4_bg_num_gdb(struct super_block *sb, ext4_group_t group)
841 unsigned long first_meta_bg =
842 le32_to_cpu(EXT4_SB(sb)->s_es->s_first_meta_bg);
843 unsigned long metagroup = group / EXT4_DESC_PER_BLOCK(sb);
845 if (!ext4_has_feature_meta_bg(sb) || metagroup < first_meta_bg)
846 return ext4_bg_num_gdb_nometa(sb, group);
848 return ext4_bg_num_gdb_meta(sb,group);
853 * This function returns the number of file system metadata clusters at
854 * the beginning of a block group, including the reserved gdt blocks.
856 static unsigned ext4_num_base_meta_clusters(struct super_block *sb,
857 ext4_group_t block_group)
859 struct ext4_sb_info *sbi = EXT4_SB(sb);
862 /* Check for superblock and gdt backups in this group */
863 num = ext4_bg_has_super(sb, block_group);
865 if (!ext4_has_feature_meta_bg(sb) ||
866 block_group < le32_to_cpu(sbi->s_es->s_first_meta_bg) *
867 sbi->s_desc_per_block) {
869 num += ext4_bg_num_gdb(sb, block_group);
870 num += le16_to_cpu(sbi->s_es->s_reserved_gdt_blocks);
872 } else { /* For META_BG_BLOCK_GROUPS */
873 num += ext4_bg_num_gdb(sb, block_group);
875 return EXT4_NUM_B2C(sbi, num);
878 * ext4_inode_to_goal_block - return a hint for block allocation
879 * @inode: inode for block allocation
881 * Return the ideal location to start allocating blocks for a
882 * newly created inode.
884 ext4_fsblk_t ext4_inode_to_goal_block(struct inode *inode)
886 struct ext4_inode_info *ei = EXT4_I(inode);
887 ext4_group_t block_group;
888 ext4_grpblk_t colour;
889 int flex_size = ext4_flex_bg_size(EXT4_SB(inode->i_sb));
890 ext4_fsblk_t bg_start;
891 ext4_fsblk_t last_block;
893 block_group = ei->i_block_group;
894 if (flex_size >= EXT4_FLEX_SIZE_DIR_ALLOC_SCHEME) {
896 * If there are at least EXT4_FLEX_SIZE_DIR_ALLOC_SCHEME
897 * block groups per flexgroup, reserve the first block
898 * group for directories and special files. Regular
899 * files will start at the second block group. This
900 * tends to speed up directory access and improves
903 block_group &= ~(flex_size-1);
904 if (S_ISREG(inode->i_mode))
907 bg_start = ext4_group_first_block_no(inode->i_sb, block_group);
908 last_block = ext4_blocks_count(EXT4_SB(inode->i_sb)->s_es) - 1;
911 * If we are doing delayed allocation, we don't need take
912 * colour into account.
914 if (test_opt(inode->i_sb, DELALLOC))
917 if (bg_start + EXT4_BLOCKS_PER_GROUP(inode->i_sb) <= last_block)
918 colour = (task_pid_nr(current) % 16) *
919 (EXT4_BLOCKS_PER_GROUP(inode->i_sb) / 16);
921 colour = (task_pid_nr(current) % 16) *
922 ((last_block - bg_start) / 16);
923 return bg_start + colour;