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