Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/sparc-2.6
[linux-2.6/mini2440.git] / fs / ext4 / balloc.c
blob53c72ad85877314c16c0eef0f19fb3889a6743da
1 /*
2 * linux/fs/ext4/balloc.c
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)
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
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 "group.h"
23 #include "mballoc.h"
26 * balloc.c contains the blocks allocation and deallocation routines
30 * Calculate the block group number and offset, given a block number
32 void ext4_get_group_no_and_offset(struct super_block *sb, ext4_fsblk_t blocknr,
33 ext4_group_t *blockgrpp, ext4_grpblk_t *offsetp)
35 struct ext4_super_block *es = EXT4_SB(sb)->s_es;
36 ext4_grpblk_t offset;
38 blocknr = blocknr - le32_to_cpu(es->s_first_data_block);
39 offset = do_div(blocknr, EXT4_BLOCKS_PER_GROUP(sb));
40 if (offsetp)
41 *offsetp = offset;
42 if (blockgrpp)
43 *blockgrpp = blocknr;
47 static int ext4_block_in_group(struct super_block *sb, ext4_fsblk_t block,
48 ext4_group_t block_group)
50 ext4_group_t actual_group;
51 ext4_get_group_no_and_offset(sb, block, &actual_group, NULL);
52 if (actual_group == block_group)
53 return 1;
54 return 0;
57 static int ext4_group_used_meta_blocks(struct super_block *sb,
58 ext4_group_t block_group,
59 struct ext4_group_desc *gdp)
61 ext4_fsblk_t tmp;
62 struct ext4_sb_info *sbi = EXT4_SB(sb);
63 /* block bitmap, inode bitmap, and inode table blocks */
64 int used_blocks = sbi->s_itb_per_group + 2;
66 if (EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_FLEX_BG)) {
67 if (!ext4_block_in_group(sb, ext4_block_bitmap(sb, gdp),
68 block_group))
69 used_blocks--;
71 if (!ext4_block_in_group(sb, ext4_inode_bitmap(sb, gdp),
72 block_group))
73 used_blocks--;
75 tmp = ext4_inode_table(sb, gdp);
76 for (; tmp < ext4_inode_table(sb, gdp) +
77 sbi->s_itb_per_group; tmp++) {
78 if (!ext4_block_in_group(sb, tmp, block_group))
79 used_blocks -= 1;
82 return used_blocks;
85 /* Initializes an uninitialized block bitmap if given, and returns the
86 * number of blocks free in the group. */
87 unsigned ext4_init_block_bitmap(struct super_block *sb, struct buffer_head *bh,
88 ext4_group_t block_group, struct ext4_group_desc *gdp)
90 int bit, bit_max;
91 unsigned free_blocks, group_blocks;
92 struct ext4_sb_info *sbi = EXT4_SB(sb);
94 if (bh) {
95 J_ASSERT_BH(bh, buffer_locked(bh));
97 /* If checksum is bad mark all blocks used to prevent allocation
98 * essentially implementing a per-group read-only flag. */
99 if (!ext4_group_desc_csum_verify(sbi, block_group, gdp)) {
100 ext4_error(sb, __func__,
101 "Checksum bad for group %u", block_group);
102 ext4_free_blks_set(sb, gdp, 0);
103 ext4_free_inodes_set(sb, gdp, 0);
104 ext4_itable_unused_set(sb, gdp, 0);
105 memset(bh->b_data, 0xff, sb->s_blocksize);
106 return 0;
108 memset(bh->b_data, 0, sb->s_blocksize);
111 /* Check for superblock and gdt backups in this group */
112 bit_max = ext4_bg_has_super(sb, block_group);
114 if (!EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_META_BG) ||
115 block_group < le32_to_cpu(sbi->s_es->s_first_meta_bg) *
116 sbi->s_desc_per_block) {
117 if (bit_max) {
118 bit_max += ext4_bg_num_gdb(sb, block_group);
119 bit_max +=
120 le16_to_cpu(sbi->s_es->s_reserved_gdt_blocks);
122 } else { /* For META_BG_BLOCK_GROUPS */
123 bit_max += ext4_bg_num_gdb(sb, block_group);
126 if (block_group == sbi->s_groups_count - 1) {
128 * Even though mke2fs always initialize first and last group
129 * if some other tool enabled the EXT4_BG_BLOCK_UNINIT we need
130 * to make sure we calculate the right free blocks
132 group_blocks = ext4_blocks_count(sbi->s_es) -
133 le32_to_cpu(sbi->s_es->s_first_data_block) -
134 (EXT4_BLOCKS_PER_GROUP(sb) * (sbi->s_groups_count - 1));
135 } else {
136 group_blocks = EXT4_BLOCKS_PER_GROUP(sb);
139 free_blocks = group_blocks - bit_max;
141 if (bh) {
142 ext4_fsblk_t start, tmp;
143 int flex_bg = 0;
145 for (bit = 0; bit < bit_max; bit++)
146 ext4_set_bit(bit, bh->b_data);
148 start = ext4_group_first_block_no(sb, block_group);
150 if (EXT4_HAS_INCOMPAT_FEATURE(sb,
151 EXT4_FEATURE_INCOMPAT_FLEX_BG))
152 flex_bg = 1;
154 /* Set bits for block and inode bitmaps, and inode table */
155 tmp = ext4_block_bitmap(sb, gdp);
156 if (!flex_bg || ext4_block_in_group(sb, tmp, block_group))
157 ext4_set_bit(tmp - start, bh->b_data);
159 tmp = ext4_inode_bitmap(sb, gdp);
160 if (!flex_bg || ext4_block_in_group(sb, tmp, block_group))
161 ext4_set_bit(tmp - start, bh->b_data);
163 tmp = ext4_inode_table(sb, gdp);
164 for (; tmp < ext4_inode_table(sb, gdp) +
165 sbi->s_itb_per_group; tmp++) {
166 if (!flex_bg ||
167 ext4_block_in_group(sb, tmp, block_group))
168 ext4_set_bit(tmp - start, bh->b_data);
171 * Also if the number of blocks within the group is
172 * less than the blocksize * 8 ( which is the size
173 * of bitmap ), set rest of the block bitmap to 1
175 mark_bitmap_end(group_blocks, sb->s_blocksize * 8, bh->b_data);
177 return free_blocks - ext4_group_used_meta_blocks(sb, block_group, gdp);
182 * The free blocks are managed by bitmaps. A file system contains several
183 * blocks groups. Each group contains 1 bitmap block for blocks, 1 bitmap
184 * block for inodes, N blocks for the inode table and data blocks.
186 * The file system contains group descriptors which are located after the
187 * super block. Each descriptor contains the number of the bitmap block and
188 * the free blocks count in the block. The descriptors are loaded in memory
189 * when a file system is mounted (see ext4_fill_super).
193 #define in_range(b, first, len) ((b) >= (first) && (b) <= (first) + (len) - 1)
196 * ext4_get_group_desc() -- load group descriptor from disk
197 * @sb: super block
198 * @block_group: given block group
199 * @bh: pointer to the buffer head to store the block
200 * group descriptor
202 struct ext4_group_desc * ext4_get_group_desc(struct super_block *sb,
203 ext4_group_t block_group,
204 struct buffer_head **bh)
206 unsigned int group_desc;
207 unsigned int offset;
208 struct ext4_group_desc *desc;
209 struct ext4_sb_info *sbi = EXT4_SB(sb);
211 if (block_group >= sbi->s_groups_count) {
212 ext4_error(sb, "ext4_get_group_desc",
213 "block_group >= groups_count - "
214 "block_group = %u, groups_count = %u",
215 block_group, sbi->s_groups_count);
217 return NULL;
219 smp_rmb();
221 group_desc = block_group >> EXT4_DESC_PER_BLOCK_BITS(sb);
222 offset = block_group & (EXT4_DESC_PER_BLOCK(sb) - 1);
223 if (!sbi->s_group_desc[group_desc]) {
224 ext4_error(sb, "ext4_get_group_desc",
225 "Group descriptor not loaded - "
226 "block_group = %u, group_desc = %u, desc = %u",
227 block_group, group_desc, offset);
228 return NULL;
231 desc = (struct ext4_group_desc *)(
232 (__u8 *)sbi->s_group_desc[group_desc]->b_data +
233 offset * EXT4_DESC_SIZE(sb));
234 if (bh)
235 *bh = sbi->s_group_desc[group_desc];
236 return desc;
239 static int ext4_valid_block_bitmap(struct super_block *sb,
240 struct ext4_group_desc *desc,
241 unsigned int block_group,
242 struct buffer_head *bh)
244 ext4_grpblk_t offset;
245 ext4_grpblk_t next_zero_bit;
246 ext4_fsblk_t bitmap_blk;
247 ext4_fsblk_t group_first_block;
249 if (EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_FLEX_BG)) {
250 /* with FLEX_BG, the inode/block bitmaps and itable
251 * blocks may not be in the group at all
252 * so the bitmap validation will be skipped for those groups
253 * or it has to also read the block group where the bitmaps
254 * are located to verify they are set.
256 return 1;
258 group_first_block = ext4_group_first_block_no(sb, block_group);
260 /* check whether block bitmap block number is set */
261 bitmap_blk = ext4_block_bitmap(sb, desc);
262 offset = bitmap_blk - group_first_block;
263 if (!ext4_test_bit(offset, bh->b_data))
264 /* bad block bitmap */
265 goto err_out;
267 /* check whether the inode bitmap block number is set */
268 bitmap_blk = ext4_inode_bitmap(sb, desc);
269 offset = bitmap_blk - group_first_block;
270 if (!ext4_test_bit(offset, bh->b_data))
271 /* bad block bitmap */
272 goto err_out;
274 /* check whether the inode table block number is set */
275 bitmap_blk = ext4_inode_table(sb, desc);
276 offset = bitmap_blk - group_first_block;
277 next_zero_bit = ext4_find_next_zero_bit(bh->b_data,
278 offset + EXT4_SB(sb)->s_itb_per_group,
279 offset);
280 if (next_zero_bit >= offset + EXT4_SB(sb)->s_itb_per_group)
281 /* good bitmap for inode tables */
282 return 1;
284 err_out:
285 ext4_error(sb, __func__,
286 "Invalid block bitmap - "
287 "block_group = %d, block = %llu",
288 block_group, bitmap_blk);
289 return 0;
292 * ext4_read_block_bitmap()
293 * @sb: super block
294 * @block_group: given block group
296 * Read the bitmap for a given block_group,and validate the
297 * bits for block/inode/inode tables are set in the bitmaps
299 * Return buffer_head on success or NULL in case of failure.
301 struct buffer_head *
302 ext4_read_block_bitmap(struct super_block *sb, ext4_group_t block_group)
304 struct ext4_group_desc *desc;
305 struct buffer_head *bh = NULL;
306 ext4_fsblk_t bitmap_blk;
308 desc = ext4_get_group_desc(sb, block_group, NULL);
309 if (!desc)
310 return NULL;
311 bitmap_blk = ext4_block_bitmap(sb, desc);
312 bh = sb_getblk(sb, bitmap_blk);
313 if (unlikely(!bh)) {
314 ext4_error(sb, __func__,
315 "Cannot read block bitmap - "
316 "block_group = %u, block_bitmap = %llu",
317 block_group, bitmap_blk);
318 return NULL;
321 if (bitmap_uptodate(bh))
322 return bh;
324 lock_buffer(bh);
325 if (bitmap_uptodate(bh)) {
326 unlock_buffer(bh);
327 return bh;
329 spin_lock(sb_bgl_lock(EXT4_SB(sb), block_group));
330 if (desc->bg_flags & cpu_to_le16(EXT4_BG_BLOCK_UNINIT)) {
331 ext4_init_block_bitmap(sb, bh, block_group, desc);
332 set_bitmap_uptodate(bh);
333 set_buffer_uptodate(bh);
334 spin_unlock(sb_bgl_lock(EXT4_SB(sb), block_group));
335 unlock_buffer(bh);
336 return bh;
338 spin_unlock(sb_bgl_lock(EXT4_SB(sb), block_group));
339 if (buffer_uptodate(bh)) {
341 * if not uninit if bh is uptodate,
342 * bitmap is also uptodate
344 set_bitmap_uptodate(bh);
345 unlock_buffer(bh);
346 return bh;
349 * submit the buffer_head for read. We can
350 * safely mark the bitmap as uptodate now.
351 * We do it here so the bitmap uptodate bit
352 * get set with buffer lock held.
354 set_bitmap_uptodate(bh);
355 if (bh_submit_read(bh) < 0) {
356 put_bh(bh);
357 ext4_error(sb, __func__,
358 "Cannot read block bitmap - "
359 "block_group = %u, block_bitmap = %llu",
360 block_group, bitmap_blk);
361 return NULL;
363 ext4_valid_block_bitmap(sb, desc, block_group, bh);
365 * file system mounted not to panic on error,
366 * continue with corrupt bitmap
368 return bh;
372 * ext4_add_groupblocks() -- Add given blocks to an existing group
373 * @handle: handle to this transaction
374 * @sb: super block
375 * @block: start physcial block to add to the block group
376 * @count: number of blocks to free
378 * This marks the blocks as free in the bitmap. We ask the
379 * mballoc to reload the buddy after this by setting group
380 * EXT4_GROUP_INFO_NEED_INIT_BIT flag
382 void ext4_add_groupblocks(handle_t *handle, struct super_block *sb,
383 ext4_fsblk_t block, unsigned long count)
385 struct buffer_head *bitmap_bh = NULL;
386 struct buffer_head *gd_bh;
387 ext4_group_t block_group;
388 ext4_grpblk_t bit;
389 unsigned int i;
390 struct ext4_group_desc *desc;
391 struct ext4_super_block *es;
392 struct ext4_sb_info *sbi;
393 int err = 0, ret, blk_free_count;
394 ext4_grpblk_t blocks_freed;
395 struct ext4_group_info *grp;
397 sbi = EXT4_SB(sb);
398 es = sbi->s_es;
399 ext4_debug("Adding block(s) %llu-%llu\n", block, block + count - 1);
401 ext4_get_group_no_and_offset(sb, block, &block_group, &bit);
402 grp = ext4_get_group_info(sb, block_group);
404 * Check to see if we are freeing blocks across a group
405 * boundary.
407 if (bit + count > EXT4_BLOCKS_PER_GROUP(sb)) {
408 goto error_return;
410 bitmap_bh = ext4_read_block_bitmap(sb, block_group);
411 if (!bitmap_bh)
412 goto error_return;
413 desc = ext4_get_group_desc(sb, block_group, &gd_bh);
414 if (!desc)
415 goto error_return;
417 if (in_range(ext4_block_bitmap(sb, desc), block, count) ||
418 in_range(ext4_inode_bitmap(sb, desc), block, count) ||
419 in_range(block, ext4_inode_table(sb, desc), sbi->s_itb_per_group) ||
420 in_range(block + count - 1, ext4_inode_table(sb, desc),
421 sbi->s_itb_per_group)) {
422 ext4_error(sb, __func__,
423 "Adding blocks in system zones - "
424 "Block = %llu, count = %lu",
425 block, count);
426 goto error_return;
430 * We are about to add blocks to the bitmap,
431 * so we need undo access.
433 BUFFER_TRACE(bitmap_bh, "getting undo access");
434 err = ext4_journal_get_undo_access(handle, bitmap_bh);
435 if (err)
436 goto error_return;
439 * We are about to modify some metadata. Call the journal APIs
440 * to unshare ->b_data if a currently-committing transaction is
441 * using it
443 BUFFER_TRACE(gd_bh, "get_write_access");
444 err = ext4_journal_get_write_access(handle, gd_bh);
445 if (err)
446 goto error_return;
448 * make sure we don't allow a parallel init on other groups in the
449 * same buddy cache
451 down_write(&grp->alloc_sem);
452 for (i = 0, blocks_freed = 0; i < count; i++) {
453 BUFFER_TRACE(bitmap_bh, "clear bit");
454 if (!ext4_clear_bit_atomic(sb_bgl_lock(sbi, block_group),
455 bit + i, bitmap_bh->b_data)) {
456 ext4_error(sb, __func__,
457 "bit already cleared for block %llu",
458 (ext4_fsblk_t)(block + i));
459 BUFFER_TRACE(bitmap_bh, "bit already cleared");
460 } else {
461 blocks_freed++;
464 spin_lock(sb_bgl_lock(sbi, block_group));
465 blk_free_count = blocks_freed + ext4_free_blks_count(sb, desc);
466 ext4_free_blks_set(sb, desc, blk_free_count);
467 desc->bg_checksum = ext4_group_desc_csum(sbi, block_group, desc);
468 spin_unlock(sb_bgl_lock(sbi, block_group));
469 percpu_counter_add(&sbi->s_freeblocks_counter, blocks_freed);
471 if (sbi->s_log_groups_per_flex) {
472 ext4_group_t flex_group = ext4_flex_group(sbi, block_group);
473 atomic_add(blocks_freed,
474 &sbi->s_flex_groups[flex_group].free_blocks);
477 * request to reload the buddy with the
478 * new bitmap information
480 set_bit(EXT4_GROUP_INFO_NEED_INIT_BIT, &(grp->bb_state));
481 ext4_mb_update_group_info(grp, blocks_freed);
482 up_write(&grp->alloc_sem);
484 /* We dirtied the bitmap block */
485 BUFFER_TRACE(bitmap_bh, "dirtied bitmap block");
486 err = ext4_handle_dirty_metadata(handle, NULL, bitmap_bh);
488 /* And the group descriptor block */
489 BUFFER_TRACE(gd_bh, "dirtied group descriptor block");
490 ret = ext4_handle_dirty_metadata(handle, NULL, gd_bh);
491 if (!err)
492 err = ret;
493 sb->s_dirt = 1;
495 error_return:
496 brelse(bitmap_bh);
497 ext4_std_error(sb, err);
498 return;
502 * ext4_free_blocks() -- Free given blocks and update quota
503 * @handle: handle for this transaction
504 * @inode: inode
505 * @block: start physical block to free
506 * @count: number of blocks to count
507 * @metadata: Are these metadata blocks
509 void ext4_free_blocks(handle_t *handle, struct inode *inode,
510 ext4_fsblk_t block, unsigned long count,
511 int metadata)
513 struct super_block *sb;
514 unsigned long dquot_freed_blocks;
516 /* this isn't the right place to decide whether block is metadata
517 * inode.c/extents.c knows better, but for safety ... */
518 if (S_ISDIR(inode->i_mode) || S_ISLNK(inode->i_mode))
519 metadata = 1;
521 /* We need to make sure we don't reuse
522 * block released untill the transaction commit.
523 * writeback mode have weak data consistency so
524 * don't force data as metadata when freeing block
525 * for writeback mode.
527 if (metadata == 0 && !ext4_should_writeback_data(inode))
528 metadata = 1;
530 sb = inode->i_sb;
532 ext4_mb_free_blocks(handle, inode, block, count,
533 metadata, &dquot_freed_blocks);
534 if (dquot_freed_blocks)
535 vfs_dq_free_block(inode, dquot_freed_blocks);
536 return;
540 * ext4_has_free_blocks()
541 * @sbi: in-core super block structure.
542 * @nblocks: number of needed blocks
544 * Check if filesystem has nblocks free & available for allocation.
545 * On success return 1, return 0 on failure.
547 int ext4_has_free_blocks(struct ext4_sb_info *sbi, s64 nblocks)
549 s64 free_blocks, dirty_blocks, root_blocks;
550 struct percpu_counter *fbc = &sbi->s_freeblocks_counter;
551 struct percpu_counter *dbc = &sbi->s_dirtyblocks_counter;
553 free_blocks = percpu_counter_read_positive(fbc);
554 dirty_blocks = percpu_counter_read_positive(dbc);
555 root_blocks = ext4_r_blocks_count(sbi->s_es);
557 if (free_blocks - (nblocks + root_blocks + dirty_blocks) <
558 EXT4_FREEBLOCKS_WATERMARK) {
559 free_blocks = percpu_counter_sum_positive(fbc);
560 dirty_blocks = percpu_counter_sum_positive(dbc);
561 if (dirty_blocks < 0) {
562 printk(KERN_CRIT "Dirty block accounting "
563 "went wrong %lld\n",
564 (long long)dirty_blocks);
567 /* Check whether we have space after
568 * accounting for current dirty blocks & root reserved blocks.
570 if (free_blocks >= ((root_blocks + nblocks) + dirty_blocks))
571 return 1;
573 /* Hm, nope. Are (enough) root reserved blocks available? */
574 if (sbi->s_resuid == current_fsuid() ||
575 ((sbi->s_resgid != 0) && in_group_p(sbi->s_resgid)) ||
576 capable(CAP_SYS_RESOURCE)) {
577 if (free_blocks >= (nblocks + dirty_blocks))
578 return 1;
581 return 0;
584 int ext4_claim_free_blocks(struct ext4_sb_info *sbi,
585 s64 nblocks)
587 if (ext4_has_free_blocks(sbi, nblocks)) {
588 percpu_counter_add(&sbi->s_dirtyblocks_counter, nblocks);
589 return 0;
590 } else
591 return -ENOSPC;
595 * ext4_should_retry_alloc()
596 * @sb: super block
597 * @retries number of attemps has been made
599 * ext4_should_retry_alloc() is called when ENOSPC is returned, and if
600 * it is profitable to retry the operation, this function will wait
601 * for the current or commiting transaction to complete, and then
602 * return TRUE.
604 * if the total number of retries exceed three times, return FALSE.
606 int ext4_should_retry_alloc(struct super_block *sb, int *retries)
608 if (!ext4_has_free_blocks(EXT4_SB(sb), 1) ||
609 (*retries)++ > 3 ||
610 !EXT4_SB(sb)->s_journal)
611 return 0;
613 jbd_debug(1, "%s: retrying operation after ENOSPC\n", sb->s_id);
615 return jbd2_journal_force_commit_nested(EXT4_SB(sb)->s_journal);
619 * ext4_new_meta_blocks() -- allocate block for meta data (indexing) blocks
621 * @handle: handle to this transaction
622 * @inode: file inode
623 * @goal: given target block(filesystem wide)
624 * @count: pointer to total number of blocks needed
625 * @errp: error code
627 * Return 1st allocated block number on success, *count stores total account
628 * error stores in errp pointer
630 ext4_fsblk_t ext4_new_meta_blocks(handle_t *handle, struct inode *inode,
631 ext4_fsblk_t goal, unsigned long *count, int *errp)
633 struct ext4_allocation_request ar;
634 ext4_fsblk_t ret;
636 memset(&ar, 0, sizeof(ar));
637 /* Fill with neighbour allocated blocks */
638 ar.inode = inode;
639 ar.goal = goal;
640 ar.len = count ? *count : 1;
642 ret = ext4_mb_new_blocks(handle, &ar, errp);
643 if (count)
644 *count = ar.len;
647 * Account for the allocated meta blocks
649 if (!(*errp) && EXT4_I(inode)->i_delalloc_reserved_flag) {
650 spin_lock(&EXT4_I(inode)->i_block_reservation_lock);
651 EXT4_I(inode)->i_allocated_meta_blocks += ar.len;
652 spin_unlock(&EXT4_I(inode)->i_block_reservation_lock);
654 return ret;
658 * ext4_count_free_blocks() -- count filesystem free blocks
659 * @sb: superblock
661 * Adds up the number of free blocks from each block group.
663 ext4_fsblk_t ext4_count_free_blocks(struct super_block *sb)
665 ext4_fsblk_t desc_count;
666 struct ext4_group_desc *gdp;
667 ext4_group_t i;
668 ext4_group_t ngroups = EXT4_SB(sb)->s_groups_count;
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;
675 es = EXT4_SB(sb)->s_es;
676 desc_count = 0;
677 bitmap_count = 0;
678 gdp = NULL;
680 smp_rmb();
681 for (i = 0; i < ngroups; i++) {
682 gdp = ext4_get_group_desc(sb, i, NULL);
683 if (!gdp)
684 continue;
685 desc_count += ext4_free_blks_count(sb, gdp);
686 brelse(bitmap_bh);
687 bitmap_bh = ext4_read_block_bitmap(sb, i);
688 if (bitmap_bh == NULL)
689 continue;
691 x = ext4_count_free(bitmap_bh, sb->s_blocksize);
692 printk(KERN_DEBUG "group %u: stored = %d, counted = %u\n",
693 i, ext4_free_blks_count(sb, gdp), x);
694 bitmap_count += x;
696 brelse(bitmap_bh);
697 printk(KERN_DEBUG "ext4_count_free_blocks: stored = %llu"
698 ", computed = %llu, %llu\n", ext4_free_blocks_count(es),
699 desc_count, bitmap_count);
700 return bitmap_count;
701 #else
702 desc_count = 0;
703 smp_rmb();
704 for (i = 0; i < ngroups; i++) {
705 gdp = ext4_get_group_desc(sb, i, NULL);
706 if (!gdp)
707 continue;
708 desc_count += ext4_free_blks_count(sb, gdp);
711 return desc_count;
712 #endif
715 static inline int test_root(ext4_group_t a, int b)
717 int num = b;
719 while (a > num)
720 num *= b;
721 return num == a;
724 static int ext4_group_sparse(ext4_group_t group)
726 if (group <= 1)
727 return 1;
728 if (!(group & 1))
729 return 0;
730 return (test_root(group, 7) || test_root(group, 5) ||
731 test_root(group, 3));
735 * ext4_bg_has_super - number of blocks used by the superblock in group
736 * @sb: superblock for filesystem
737 * @group: group number to check
739 * Return the number of blocks used by the superblock (primary or backup)
740 * in this group. Currently this will be only 0 or 1.
742 int ext4_bg_has_super(struct super_block *sb, ext4_group_t group)
744 if (EXT4_HAS_RO_COMPAT_FEATURE(sb,
745 EXT4_FEATURE_RO_COMPAT_SPARSE_SUPER) &&
746 !ext4_group_sparse(group))
747 return 0;
748 return 1;
751 static unsigned long ext4_bg_num_gdb_meta(struct super_block *sb,
752 ext4_group_t group)
754 unsigned long metagroup = group / EXT4_DESC_PER_BLOCK(sb);
755 ext4_group_t first = metagroup * EXT4_DESC_PER_BLOCK(sb);
756 ext4_group_t last = first + EXT4_DESC_PER_BLOCK(sb) - 1;
758 if (group == first || group == first + 1 || group == last)
759 return 1;
760 return 0;
763 static unsigned long ext4_bg_num_gdb_nometa(struct super_block *sb,
764 ext4_group_t group)
766 return ext4_bg_has_super(sb, group) ? EXT4_SB(sb)->s_gdb_count : 0;
770 * ext4_bg_num_gdb - number of blocks used by the group table in group
771 * @sb: superblock for filesystem
772 * @group: group number to check
774 * Return the number of blocks used by the group descriptor table
775 * (primary or backup) in this group. In the future there may be a
776 * different number of descriptor blocks in each group.
778 unsigned long ext4_bg_num_gdb(struct super_block *sb, ext4_group_t group)
780 unsigned long first_meta_bg =
781 le32_to_cpu(EXT4_SB(sb)->s_es->s_first_meta_bg);
782 unsigned long metagroup = group / EXT4_DESC_PER_BLOCK(sb);
784 if (!EXT4_HAS_INCOMPAT_FEATURE(sb,EXT4_FEATURE_INCOMPAT_META_BG) ||
785 metagroup < first_meta_bg)
786 return ext4_bg_num_gdb_nometa(sb, group);
788 return ext4_bg_num_gdb_meta(sb,group);