xref: /openbmc/linux/fs/ext4/mballoc.c (revision a36954f5)
1 /*
2  * Copyright (c) 2003-2006, Cluster File Systems, Inc, info@clusterfs.com
3  * Written by Alex Tomas <alex@clusterfs.com>
4  *
5  * This program is free software; you can redistribute it and/or modify
6  * it under the terms of the GNU General Public License version 2 as
7  * published by the Free Software Foundation.
8  *
9  * This program is distributed in the hope that it will be useful,
10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
12  * GNU General Public License for more details.
13  *
14  * You should have received a copy of the GNU General Public License
15  * along with this program; if not, write to the Free Software
16  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-
17  */
18 
19 
20 /*
21  * mballoc.c contains the multiblocks allocation routines
22  */
23 
24 #include "ext4_jbd2.h"
25 #include "mballoc.h"
26 #include <linux/log2.h>
27 #include <linux/module.h>
28 #include <linux/slab.h>
29 #include <linux/backing-dev.h>
30 #include <trace/events/ext4.h>
31 
32 #ifdef CONFIG_EXT4_DEBUG
33 ushort ext4_mballoc_debug __read_mostly;
34 
35 module_param_named(mballoc_debug, ext4_mballoc_debug, ushort, 0644);
36 MODULE_PARM_DESC(mballoc_debug, "Debugging level for ext4's mballoc");
37 #endif
38 
39 /*
40  * MUSTDO:
41  *   - test ext4_ext_search_left() and ext4_ext_search_right()
42  *   - search for metadata in few groups
43  *
44  * TODO v4:
45  *   - normalization should take into account whether file is still open
46  *   - discard preallocations if no free space left (policy?)
47  *   - don't normalize tails
48  *   - quota
49  *   - reservation for superuser
50  *
51  * TODO v3:
52  *   - bitmap read-ahead (proposed by Oleg Drokin aka green)
53  *   - track min/max extents in each group for better group selection
54  *   - mb_mark_used() may allocate chunk right after splitting buddy
55  *   - tree of groups sorted by number of free blocks
56  *   - error handling
57  */
58 
59 /*
60  * The allocation request involve request for multiple number of blocks
61  * near to the goal(block) value specified.
62  *
63  * During initialization phase of the allocator we decide to use the
64  * group preallocation or inode preallocation depending on the size of
65  * the file. The size of the file could be the resulting file size we
66  * would have after allocation, or the current file size, which ever
67  * is larger. If the size is less than sbi->s_mb_stream_request we
68  * select to use the group preallocation. The default value of
69  * s_mb_stream_request is 16 blocks. This can also be tuned via
70  * /sys/fs/ext4/<partition>/mb_stream_req. The value is represented in
71  * terms of number of blocks.
72  *
73  * The main motivation for having small file use group preallocation is to
74  * ensure that we have small files closer together on the disk.
75  *
76  * First stage the allocator looks at the inode prealloc list,
77  * ext4_inode_info->i_prealloc_list, which contains list of prealloc
78  * spaces for this particular inode. The inode prealloc space is
79  * represented as:
80  *
81  * pa_lstart -> the logical start block for this prealloc space
82  * pa_pstart -> the physical start block for this prealloc space
83  * pa_len    -> length for this prealloc space (in clusters)
84  * pa_free   ->  free space available in this prealloc space (in clusters)
85  *
86  * The inode preallocation space is used looking at the _logical_ start
87  * block. If only the logical file block falls within the range of prealloc
88  * space we will consume the particular prealloc space. This makes sure that
89  * we have contiguous physical blocks representing the file blocks
90  *
91  * The important thing to be noted in case of inode prealloc space is that
92  * we don't modify the values associated to inode prealloc space except
93  * pa_free.
94  *
95  * If we are not able to find blocks in the inode prealloc space and if we
96  * have the group allocation flag set then we look at the locality group
97  * prealloc space. These are per CPU prealloc list represented as
98  *
99  * ext4_sb_info.s_locality_groups[smp_processor_id()]
100  *
101  * The reason for having a per cpu locality group is to reduce the contention
102  * between CPUs. It is possible to get scheduled at this point.
103  *
104  * The locality group prealloc space is used looking at whether we have
105  * enough free space (pa_free) within the prealloc space.
106  *
107  * If we can't allocate blocks via inode prealloc or/and locality group
108  * prealloc then we look at the buddy cache. The buddy cache is represented
109  * by ext4_sb_info.s_buddy_cache (struct inode) whose file offset gets
110  * mapped to the buddy and bitmap information regarding different
111  * groups. The buddy information is attached to buddy cache inode so that
112  * we can access them through the page cache. The information regarding
113  * each group is loaded via ext4_mb_load_buddy.  The information involve
114  * block bitmap and buddy information. The information are stored in the
115  * inode as:
116  *
117  *  {                        page                        }
118  *  [ group 0 bitmap][ group 0 buddy] [group 1][ group 1]...
119  *
120  *
121  * one block each for bitmap and buddy information.  So for each group we
122  * take up 2 blocks. A page can contain blocks_per_page (PAGE_SIZE /
123  * blocksize) blocks.  So it can have information regarding groups_per_page
124  * which is blocks_per_page/2
125  *
126  * The buddy cache inode is not stored on disk. The inode is thrown
127  * away when the filesystem is unmounted.
128  *
129  * We look for count number of blocks in the buddy cache. If we were able
130  * to locate that many free blocks we return with additional information
131  * regarding rest of the contiguous physical block available
132  *
133  * Before allocating blocks via buddy cache we normalize the request
134  * blocks. This ensure we ask for more blocks that we needed. The extra
135  * blocks that we get after allocation is added to the respective prealloc
136  * list. In case of inode preallocation we follow a list of heuristics
137  * based on file size. This can be found in ext4_mb_normalize_request. If
138  * we are doing a group prealloc we try to normalize the request to
139  * sbi->s_mb_group_prealloc.  The default value of s_mb_group_prealloc is
140  * dependent on the cluster size; for non-bigalloc file systems, it is
141  * 512 blocks. This can be tuned via
142  * /sys/fs/ext4/<partition>/mb_group_prealloc. The value is represented in
143  * terms of number of blocks. If we have mounted the file system with -O
144  * stripe=<value> option the group prealloc request is normalized to the
145  * the smallest multiple of the stripe value (sbi->s_stripe) which is
146  * greater than the default mb_group_prealloc.
147  *
148  * The regular allocator (using the buddy cache) supports a few tunables.
149  *
150  * /sys/fs/ext4/<partition>/mb_min_to_scan
151  * /sys/fs/ext4/<partition>/mb_max_to_scan
152  * /sys/fs/ext4/<partition>/mb_order2_req
153  *
154  * The regular allocator uses buddy scan only if the request len is power of
155  * 2 blocks and the order of allocation is >= sbi->s_mb_order2_reqs. The
156  * value of s_mb_order2_reqs can be tuned via
157  * /sys/fs/ext4/<partition>/mb_order2_req.  If the request len is equal to
158  * stripe size (sbi->s_stripe), we try to search for contiguous block in
159  * stripe size. This should result in better allocation on RAID setups. If
160  * not, we search in the specific group using bitmap for best extents. The
161  * tunable min_to_scan and max_to_scan control the behaviour here.
162  * min_to_scan indicate how long the mballoc __must__ look for a best
163  * extent and max_to_scan indicates how long the mballoc __can__ look for a
164  * best extent in the found extents. Searching for the blocks starts with
165  * the group specified as the goal value in allocation context via
166  * ac_g_ex. Each group is first checked based on the criteria whether it
167  * can be used for allocation. ext4_mb_good_group explains how the groups are
168  * checked.
169  *
170  * Both the prealloc space are getting populated as above. So for the first
171  * request we will hit the buddy cache which will result in this prealloc
172  * space getting filled. The prealloc space is then later used for the
173  * subsequent request.
174  */
175 
176 /*
177  * mballoc operates on the following data:
178  *  - on-disk bitmap
179  *  - in-core buddy (actually includes buddy and bitmap)
180  *  - preallocation descriptors (PAs)
181  *
182  * there are two types of preallocations:
183  *  - inode
184  *    assiged to specific inode and can be used for this inode only.
185  *    it describes part of inode's space preallocated to specific
186  *    physical blocks. any block from that preallocated can be used
187  *    independent. the descriptor just tracks number of blocks left
188  *    unused. so, before taking some block from descriptor, one must
189  *    make sure corresponded logical block isn't allocated yet. this
190  *    also means that freeing any block within descriptor's range
191  *    must discard all preallocated blocks.
192  *  - locality group
193  *    assigned to specific locality group which does not translate to
194  *    permanent set of inodes: inode can join and leave group. space
195  *    from this type of preallocation can be used for any inode. thus
196  *    it's consumed from the beginning to the end.
197  *
198  * relation between them can be expressed as:
199  *    in-core buddy = on-disk bitmap + preallocation descriptors
200  *
201  * this mean blocks mballoc considers used are:
202  *  - allocated blocks (persistent)
203  *  - preallocated blocks (non-persistent)
204  *
205  * consistency in mballoc world means that at any time a block is either
206  * free or used in ALL structures. notice: "any time" should not be read
207  * literally -- time is discrete and delimited by locks.
208  *
209  *  to keep it simple, we don't use block numbers, instead we count number of
210  *  blocks: how many blocks marked used/free in on-disk bitmap, buddy and PA.
211  *
212  * all operations can be expressed as:
213  *  - init buddy:			buddy = on-disk + PAs
214  *  - new PA:				buddy += N; PA = N
215  *  - use inode PA:			on-disk += N; PA -= N
216  *  - discard inode PA			buddy -= on-disk - PA; PA = 0
217  *  - use locality group PA		on-disk += N; PA -= N
218  *  - discard locality group PA		buddy -= PA; PA = 0
219  *  note: 'buddy -= on-disk - PA' is used to show that on-disk bitmap
220  *        is used in real operation because we can't know actual used
221  *        bits from PA, only from on-disk bitmap
222  *
223  * if we follow this strict logic, then all operations above should be atomic.
224  * given some of them can block, we'd have to use something like semaphores
225  * killing performance on high-end SMP hardware. let's try to relax it using
226  * the following knowledge:
227  *  1) if buddy is referenced, it's already initialized
228  *  2) while block is used in buddy and the buddy is referenced,
229  *     nobody can re-allocate that block
230  *  3) we work on bitmaps and '+' actually means 'set bits'. if on-disk has
231  *     bit set and PA claims same block, it's OK. IOW, one can set bit in
232  *     on-disk bitmap if buddy has same bit set or/and PA covers corresponded
233  *     block
234  *
235  * so, now we're building a concurrency table:
236  *  - init buddy vs.
237  *    - new PA
238  *      blocks for PA are allocated in the buddy, buddy must be referenced
239  *      until PA is linked to allocation group to avoid concurrent buddy init
240  *    - use inode PA
241  *      we need to make sure that either on-disk bitmap or PA has uptodate data
242  *      given (3) we care that PA-=N operation doesn't interfere with init
243  *    - discard inode PA
244  *      the simplest way would be to have buddy initialized by the discard
245  *    - use locality group PA
246  *      again PA-=N must be serialized with init
247  *    - discard locality group PA
248  *      the simplest way would be to have buddy initialized by the discard
249  *  - new PA vs.
250  *    - use inode PA
251  *      i_data_sem serializes them
252  *    - discard inode PA
253  *      discard process must wait until PA isn't used by another process
254  *    - use locality group PA
255  *      some mutex should serialize them
256  *    - discard locality group PA
257  *      discard process must wait until PA isn't used by another process
258  *  - use inode PA
259  *    - use inode PA
260  *      i_data_sem or another mutex should serializes them
261  *    - discard inode PA
262  *      discard process must wait until PA isn't used by another process
263  *    - use locality group PA
264  *      nothing wrong here -- they're different PAs covering different blocks
265  *    - discard locality group PA
266  *      discard process must wait until PA isn't used by another process
267  *
268  * now we're ready to make few consequences:
269  *  - PA is referenced and while it is no discard is possible
270  *  - PA is referenced until block isn't marked in on-disk bitmap
271  *  - PA changes only after on-disk bitmap
272  *  - discard must not compete with init. either init is done before
273  *    any discard or they're serialized somehow
274  *  - buddy init as sum of on-disk bitmap and PAs is done atomically
275  *
276  * a special case when we've used PA to emptiness. no need to modify buddy
277  * in this case, but we should care about concurrent init
278  *
279  */
280 
281  /*
282  * Logic in few words:
283  *
284  *  - allocation:
285  *    load group
286  *    find blocks
287  *    mark bits in on-disk bitmap
288  *    release group
289  *
290  *  - use preallocation:
291  *    find proper PA (per-inode or group)
292  *    load group
293  *    mark bits in on-disk bitmap
294  *    release group
295  *    release PA
296  *
297  *  - free:
298  *    load group
299  *    mark bits in on-disk bitmap
300  *    release group
301  *
302  *  - discard preallocations in group:
303  *    mark PAs deleted
304  *    move them onto local list
305  *    load on-disk bitmap
306  *    load group
307  *    remove PA from object (inode or locality group)
308  *    mark free blocks in-core
309  *
310  *  - discard inode's preallocations:
311  */
312 
313 /*
314  * Locking rules
315  *
316  * Locks:
317  *  - bitlock on a group	(group)
318  *  - object (inode/locality)	(object)
319  *  - per-pa lock		(pa)
320  *
321  * Paths:
322  *  - new pa
323  *    object
324  *    group
325  *
326  *  - find and use pa:
327  *    pa
328  *
329  *  - release consumed pa:
330  *    pa
331  *    group
332  *    object
333  *
334  *  - generate in-core bitmap:
335  *    group
336  *        pa
337  *
338  *  - discard all for given object (inode, locality group):
339  *    object
340  *        pa
341  *    group
342  *
343  *  - discard all for given group:
344  *    group
345  *        pa
346  *    group
347  *        object
348  *
349  */
350 static struct kmem_cache *ext4_pspace_cachep;
351 static struct kmem_cache *ext4_ac_cachep;
352 static struct kmem_cache *ext4_free_data_cachep;
353 
354 /* We create slab caches for groupinfo data structures based on the
355  * superblock block size.  There will be one per mounted filesystem for
356  * each unique s_blocksize_bits */
357 #define NR_GRPINFO_CACHES 8
358 static struct kmem_cache *ext4_groupinfo_caches[NR_GRPINFO_CACHES];
359 
360 static const char * const ext4_groupinfo_slab_names[NR_GRPINFO_CACHES] = {
361 	"ext4_groupinfo_1k", "ext4_groupinfo_2k", "ext4_groupinfo_4k",
362 	"ext4_groupinfo_8k", "ext4_groupinfo_16k", "ext4_groupinfo_32k",
363 	"ext4_groupinfo_64k", "ext4_groupinfo_128k"
364 };
365 
366 static void ext4_mb_generate_from_pa(struct super_block *sb, void *bitmap,
367 					ext4_group_t group);
368 static void ext4_mb_generate_from_freelist(struct super_block *sb, void *bitmap,
369 						ext4_group_t group);
370 static void ext4_free_data_callback(struct super_block *sb,
371 				struct ext4_journal_cb_entry *jce, int rc);
372 
373 static inline void *mb_correct_addr_and_bit(int *bit, void *addr)
374 {
375 #if BITS_PER_LONG == 64
376 	*bit += ((unsigned long) addr & 7UL) << 3;
377 	addr = (void *) ((unsigned long) addr & ~7UL);
378 #elif BITS_PER_LONG == 32
379 	*bit += ((unsigned long) addr & 3UL) << 3;
380 	addr = (void *) ((unsigned long) addr & ~3UL);
381 #else
382 #error "how many bits you are?!"
383 #endif
384 	return addr;
385 }
386 
387 static inline int mb_test_bit(int bit, void *addr)
388 {
389 	/*
390 	 * ext4_test_bit on architecture like powerpc
391 	 * needs unsigned long aligned address
392 	 */
393 	addr = mb_correct_addr_and_bit(&bit, addr);
394 	return ext4_test_bit(bit, addr);
395 }
396 
397 static inline void mb_set_bit(int bit, void *addr)
398 {
399 	addr = mb_correct_addr_and_bit(&bit, addr);
400 	ext4_set_bit(bit, addr);
401 }
402 
403 static inline void mb_clear_bit(int bit, void *addr)
404 {
405 	addr = mb_correct_addr_and_bit(&bit, addr);
406 	ext4_clear_bit(bit, addr);
407 }
408 
409 static inline int mb_test_and_clear_bit(int bit, void *addr)
410 {
411 	addr = mb_correct_addr_and_bit(&bit, addr);
412 	return ext4_test_and_clear_bit(bit, addr);
413 }
414 
415 static inline int mb_find_next_zero_bit(void *addr, int max, int start)
416 {
417 	int fix = 0, ret, tmpmax;
418 	addr = mb_correct_addr_and_bit(&fix, addr);
419 	tmpmax = max + fix;
420 	start += fix;
421 
422 	ret = ext4_find_next_zero_bit(addr, tmpmax, start) - fix;
423 	if (ret > max)
424 		return max;
425 	return ret;
426 }
427 
428 static inline int mb_find_next_bit(void *addr, int max, int start)
429 {
430 	int fix = 0, ret, tmpmax;
431 	addr = mb_correct_addr_and_bit(&fix, addr);
432 	tmpmax = max + fix;
433 	start += fix;
434 
435 	ret = ext4_find_next_bit(addr, tmpmax, start) - fix;
436 	if (ret > max)
437 		return max;
438 	return ret;
439 }
440 
441 static void *mb_find_buddy(struct ext4_buddy *e4b, int order, int *max)
442 {
443 	char *bb;
444 
445 	BUG_ON(e4b->bd_bitmap == e4b->bd_buddy);
446 	BUG_ON(max == NULL);
447 
448 	if (order > e4b->bd_blkbits + 1) {
449 		*max = 0;
450 		return NULL;
451 	}
452 
453 	/* at order 0 we see each particular block */
454 	if (order == 0) {
455 		*max = 1 << (e4b->bd_blkbits + 3);
456 		return e4b->bd_bitmap;
457 	}
458 
459 	bb = e4b->bd_buddy + EXT4_SB(e4b->bd_sb)->s_mb_offsets[order];
460 	*max = EXT4_SB(e4b->bd_sb)->s_mb_maxs[order];
461 
462 	return bb;
463 }
464 
465 #ifdef DOUBLE_CHECK
466 static void mb_free_blocks_double(struct inode *inode, struct ext4_buddy *e4b,
467 			   int first, int count)
468 {
469 	int i;
470 	struct super_block *sb = e4b->bd_sb;
471 
472 	if (unlikely(e4b->bd_info->bb_bitmap == NULL))
473 		return;
474 	assert_spin_locked(ext4_group_lock_ptr(sb, e4b->bd_group));
475 	for (i = 0; i < count; i++) {
476 		if (!mb_test_bit(first + i, e4b->bd_info->bb_bitmap)) {
477 			ext4_fsblk_t blocknr;
478 
479 			blocknr = ext4_group_first_block_no(sb, e4b->bd_group);
480 			blocknr += EXT4_C2B(EXT4_SB(sb), first + i);
481 			ext4_grp_locked_error(sb, e4b->bd_group,
482 					      inode ? inode->i_ino : 0,
483 					      blocknr,
484 					      "freeing block already freed "
485 					      "(bit %u)",
486 					      first + i);
487 		}
488 		mb_clear_bit(first + i, e4b->bd_info->bb_bitmap);
489 	}
490 }
491 
492 static void mb_mark_used_double(struct ext4_buddy *e4b, int first, int count)
493 {
494 	int i;
495 
496 	if (unlikely(e4b->bd_info->bb_bitmap == NULL))
497 		return;
498 	assert_spin_locked(ext4_group_lock_ptr(e4b->bd_sb, e4b->bd_group));
499 	for (i = 0; i < count; i++) {
500 		BUG_ON(mb_test_bit(first + i, e4b->bd_info->bb_bitmap));
501 		mb_set_bit(first + i, e4b->bd_info->bb_bitmap);
502 	}
503 }
504 
505 static void mb_cmp_bitmaps(struct ext4_buddy *e4b, void *bitmap)
506 {
507 	if (memcmp(e4b->bd_info->bb_bitmap, bitmap, e4b->bd_sb->s_blocksize)) {
508 		unsigned char *b1, *b2;
509 		int i;
510 		b1 = (unsigned char *) e4b->bd_info->bb_bitmap;
511 		b2 = (unsigned char *) bitmap;
512 		for (i = 0; i < e4b->bd_sb->s_blocksize; i++) {
513 			if (b1[i] != b2[i]) {
514 				ext4_msg(e4b->bd_sb, KERN_ERR,
515 					 "corruption in group %u "
516 					 "at byte %u(%u): %x in copy != %x "
517 					 "on disk/prealloc",
518 					 e4b->bd_group, i, i * 8, b1[i], b2[i]);
519 				BUG();
520 			}
521 		}
522 	}
523 }
524 
525 #else
526 static inline void mb_free_blocks_double(struct inode *inode,
527 				struct ext4_buddy *e4b, int first, int count)
528 {
529 	return;
530 }
531 static inline void mb_mark_used_double(struct ext4_buddy *e4b,
532 						int first, int count)
533 {
534 	return;
535 }
536 static inline void mb_cmp_bitmaps(struct ext4_buddy *e4b, void *bitmap)
537 {
538 	return;
539 }
540 #endif
541 
542 #ifdef AGGRESSIVE_CHECK
543 
544 #define MB_CHECK_ASSERT(assert)						\
545 do {									\
546 	if (!(assert)) {						\
547 		printk(KERN_EMERG					\
548 			"Assertion failure in %s() at %s:%d: \"%s\"\n",	\
549 			function, file, line, # assert);		\
550 		BUG();							\
551 	}								\
552 } while (0)
553 
554 static int __mb_check_buddy(struct ext4_buddy *e4b, char *file,
555 				const char *function, int line)
556 {
557 	struct super_block *sb = e4b->bd_sb;
558 	int order = e4b->bd_blkbits + 1;
559 	int max;
560 	int max2;
561 	int i;
562 	int j;
563 	int k;
564 	int count;
565 	struct ext4_group_info *grp;
566 	int fragments = 0;
567 	int fstart;
568 	struct list_head *cur;
569 	void *buddy;
570 	void *buddy2;
571 
572 	{
573 		static int mb_check_counter;
574 		if (mb_check_counter++ % 100 != 0)
575 			return 0;
576 	}
577 
578 	while (order > 1) {
579 		buddy = mb_find_buddy(e4b, order, &max);
580 		MB_CHECK_ASSERT(buddy);
581 		buddy2 = mb_find_buddy(e4b, order - 1, &max2);
582 		MB_CHECK_ASSERT(buddy2);
583 		MB_CHECK_ASSERT(buddy != buddy2);
584 		MB_CHECK_ASSERT(max * 2 == max2);
585 
586 		count = 0;
587 		for (i = 0; i < max; i++) {
588 
589 			if (mb_test_bit(i, buddy)) {
590 				/* only single bit in buddy2 may be 1 */
591 				if (!mb_test_bit(i << 1, buddy2)) {
592 					MB_CHECK_ASSERT(
593 						mb_test_bit((i<<1)+1, buddy2));
594 				} else if (!mb_test_bit((i << 1) + 1, buddy2)) {
595 					MB_CHECK_ASSERT(
596 						mb_test_bit(i << 1, buddy2));
597 				}
598 				continue;
599 			}
600 
601 			/* both bits in buddy2 must be 1 */
602 			MB_CHECK_ASSERT(mb_test_bit(i << 1, buddy2));
603 			MB_CHECK_ASSERT(mb_test_bit((i << 1) + 1, buddy2));
604 
605 			for (j = 0; j < (1 << order); j++) {
606 				k = (i * (1 << order)) + j;
607 				MB_CHECK_ASSERT(
608 					!mb_test_bit(k, e4b->bd_bitmap));
609 			}
610 			count++;
611 		}
612 		MB_CHECK_ASSERT(e4b->bd_info->bb_counters[order] == count);
613 		order--;
614 	}
615 
616 	fstart = -1;
617 	buddy = mb_find_buddy(e4b, 0, &max);
618 	for (i = 0; i < max; i++) {
619 		if (!mb_test_bit(i, buddy)) {
620 			MB_CHECK_ASSERT(i >= e4b->bd_info->bb_first_free);
621 			if (fstart == -1) {
622 				fragments++;
623 				fstart = i;
624 			}
625 			continue;
626 		}
627 		fstart = -1;
628 		/* check used bits only */
629 		for (j = 0; j < e4b->bd_blkbits + 1; j++) {
630 			buddy2 = mb_find_buddy(e4b, j, &max2);
631 			k = i >> j;
632 			MB_CHECK_ASSERT(k < max2);
633 			MB_CHECK_ASSERT(mb_test_bit(k, buddy2));
634 		}
635 	}
636 	MB_CHECK_ASSERT(!EXT4_MB_GRP_NEED_INIT(e4b->bd_info));
637 	MB_CHECK_ASSERT(e4b->bd_info->bb_fragments == fragments);
638 
639 	grp = ext4_get_group_info(sb, e4b->bd_group);
640 	list_for_each(cur, &grp->bb_prealloc_list) {
641 		ext4_group_t groupnr;
642 		struct ext4_prealloc_space *pa;
643 		pa = list_entry(cur, struct ext4_prealloc_space, pa_group_list);
644 		ext4_get_group_no_and_offset(sb, pa->pa_pstart, &groupnr, &k);
645 		MB_CHECK_ASSERT(groupnr == e4b->bd_group);
646 		for (i = 0; i < pa->pa_len; i++)
647 			MB_CHECK_ASSERT(mb_test_bit(k + i, buddy));
648 	}
649 	return 0;
650 }
651 #undef MB_CHECK_ASSERT
652 #define mb_check_buddy(e4b) __mb_check_buddy(e4b,	\
653 					__FILE__, __func__, __LINE__)
654 #else
655 #define mb_check_buddy(e4b)
656 #endif
657 
658 /*
659  * Divide blocks started from @first with length @len into
660  * smaller chunks with power of 2 blocks.
661  * Clear the bits in bitmap which the blocks of the chunk(s) covered,
662  * then increase bb_counters[] for corresponded chunk size.
663  */
664 static void ext4_mb_mark_free_simple(struct super_block *sb,
665 				void *buddy, ext4_grpblk_t first, ext4_grpblk_t len,
666 					struct ext4_group_info *grp)
667 {
668 	struct ext4_sb_info *sbi = EXT4_SB(sb);
669 	ext4_grpblk_t min;
670 	ext4_grpblk_t max;
671 	ext4_grpblk_t chunk;
672 	unsigned int border;
673 
674 	BUG_ON(len > EXT4_CLUSTERS_PER_GROUP(sb));
675 
676 	border = 2 << sb->s_blocksize_bits;
677 
678 	while (len > 0) {
679 		/* find how many blocks can be covered since this position */
680 		max = ffs(first | border) - 1;
681 
682 		/* find how many blocks of power 2 we need to mark */
683 		min = fls(len) - 1;
684 
685 		if (max < min)
686 			min = max;
687 		chunk = 1 << min;
688 
689 		/* mark multiblock chunks only */
690 		grp->bb_counters[min]++;
691 		if (min > 0)
692 			mb_clear_bit(first >> min,
693 				     buddy + sbi->s_mb_offsets[min]);
694 
695 		len -= chunk;
696 		first += chunk;
697 	}
698 }
699 
700 /*
701  * Cache the order of the largest free extent we have available in this block
702  * group.
703  */
704 static void
705 mb_set_largest_free_order(struct super_block *sb, struct ext4_group_info *grp)
706 {
707 	int i;
708 	int bits;
709 
710 	grp->bb_largest_free_order = -1; /* uninit */
711 
712 	bits = sb->s_blocksize_bits + 1;
713 	for (i = bits; i >= 0; i--) {
714 		if (grp->bb_counters[i] > 0) {
715 			grp->bb_largest_free_order = i;
716 			break;
717 		}
718 	}
719 }
720 
721 static noinline_for_stack
722 void ext4_mb_generate_buddy(struct super_block *sb,
723 				void *buddy, void *bitmap, ext4_group_t group)
724 {
725 	struct ext4_group_info *grp = ext4_get_group_info(sb, group);
726 	struct ext4_sb_info *sbi = EXT4_SB(sb);
727 	ext4_grpblk_t max = EXT4_CLUSTERS_PER_GROUP(sb);
728 	ext4_grpblk_t i = 0;
729 	ext4_grpblk_t first;
730 	ext4_grpblk_t len;
731 	unsigned free = 0;
732 	unsigned fragments = 0;
733 	unsigned long long period = get_cycles();
734 
735 	/* initialize buddy from bitmap which is aggregation
736 	 * of on-disk bitmap and preallocations */
737 	i = mb_find_next_zero_bit(bitmap, max, 0);
738 	grp->bb_first_free = i;
739 	while (i < max) {
740 		fragments++;
741 		first = i;
742 		i = mb_find_next_bit(bitmap, max, i);
743 		len = i - first;
744 		free += len;
745 		if (len > 1)
746 			ext4_mb_mark_free_simple(sb, buddy, first, len, grp);
747 		else
748 			grp->bb_counters[0]++;
749 		if (i < max)
750 			i = mb_find_next_zero_bit(bitmap, max, i);
751 	}
752 	grp->bb_fragments = fragments;
753 
754 	if (free != grp->bb_free) {
755 		ext4_grp_locked_error(sb, group, 0, 0,
756 				      "block bitmap and bg descriptor "
757 				      "inconsistent: %u vs %u free clusters",
758 				      free, grp->bb_free);
759 		/*
760 		 * If we intend to continue, we consider group descriptor
761 		 * corrupt and update bb_free using bitmap value
762 		 */
763 		grp->bb_free = free;
764 		if (!EXT4_MB_GRP_BBITMAP_CORRUPT(grp))
765 			percpu_counter_sub(&sbi->s_freeclusters_counter,
766 					   grp->bb_free);
767 		set_bit(EXT4_GROUP_INFO_BBITMAP_CORRUPT_BIT, &grp->bb_state);
768 	}
769 	mb_set_largest_free_order(sb, grp);
770 
771 	clear_bit(EXT4_GROUP_INFO_NEED_INIT_BIT, &(grp->bb_state));
772 
773 	period = get_cycles() - period;
774 	spin_lock(&EXT4_SB(sb)->s_bal_lock);
775 	EXT4_SB(sb)->s_mb_buddies_generated++;
776 	EXT4_SB(sb)->s_mb_generation_time += period;
777 	spin_unlock(&EXT4_SB(sb)->s_bal_lock);
778 }
779 
780 static void mb_regenerate_buddy(struct ext4_buddy *e4b)
781 {
782 	int count;
783 	int order = 1;
784 	void *buddy;
785 
786 	while ((buddy = mb_find_buddy(e4b, order++, &count))) {
787 		ext4_set_bits(buddy, 0, count);
788 	}
789 	e4b->bd_info->bb_fragments = 0;
790 	memset(e4b->bd_info->bb_counters, 0,
791 		sizeof(*e4b->bd_info->bb_counters) *
792 		(e4b->bd_sb->s_blocksize_bits + 2));
793 
794 	ext4_mb_generate_buddy(e4b->bd_sb, e4b->bd_buddy,
795 		e4b->bd_bitmap, e4b->bd_group);
796 }
797 
798 /* The buddy information is attached the buddy cache inode
799  * for convenience. The information regarding each group
800  * is loaded via ext4_mb_load_buddy. The information involve
801  * block bitmap and buddy information. The information are
802  * stored in the inode as
803  *
804  * {                        page                        }
805  * [ group 0 bitmap][ group 0 buddy] [group 1][ group 1]...
806  *
807  *
808  * one block each for bitmap and buddy information.
809  * So for each group we take up 2 blocks. A page can
810  * contain blocks_per_page (PAGE_SIZE / blocksize)  blocks.
811  * So it can have information regarding groups_per_page which
812  * is blocks_per_page/2
813  *
814  * Locking note:  This routine takes the block group lock of all groups
815  * for this page; do not hold this lock when calling this routine!
816  */
817 
818 static int ext4_mb_init_cache(struct page *page, char *incore, gfp_t gfp)
819 {
820 	ext4_group_t ngroups;
821 	int blocksize;
822 	int blocks_per_page;
823 	int groups_per_page;
824 	int err = 0;
825 	int i;
826 	ext4_group_t first_group, group;
827 	int first_block;
828 	struct super_block *sb;
829 	struct buffer_head *bhs;
830 	struct buffer_head **bh = NULL;
831 	struct inode *inode;
832 	char *data;
833 	char *bitmap;
834 	struct ext4_group_info *grinfo;
835 
836 	mb_debug(1, "init page %lu\n", page->index);
837 
838 	inode = page->mapping->host;
839 	sb = inode->i_sb;
840 	ngroups = ext4_get_groups_count(sb);
841 	blocksize = i_blocksize(inode);
842 	blocks_per_page = PAGE_SIZE / blocksize;
843 
844 	groups_per_page = blocks_per_page >> 1;
845 	if (groups_per_page == 0)
846 		groups_per_page = 1;
847 
848 	/* allocate buffer_heads to read bitmaps */
849 	if (groups_per_page > 1) {
850 		i = sizeof(struct buffer_head *) * groups_per_page;
851 		bh = kzalloc(i, gfp);
852 		if (bh == NULL) {
853 			err = -ENOMEM;
854 			goto out;
855 		}
856 	} else
857 		bh = &bhs;
858 
859 	first_group = page->index * blocks_per_page / 2;
860 
861 	/* read all groups the page covers into the cache */
862 	for (i = 0, group = first_group; i < groups_per_page; i++, group++) {
863 		if (group >= ngroups)
864 			break;
865 
866 		grinfo = ext4_get_group_info(sb, group);
867 		/*
868 		 * If page is uptodate then we came here after online resize
869 		 * which added some new uninitialized group info structs, so
870 		 * we must skip all initialized uptodate buddies on the page,
871 		 * which may be currently in use by an allocating task.
872 		 */
873 		if (PageUptodate(page) && !EXT4_MB_GRP_NEED_INIT(grinfo)) {
874 			bh[i] = NULL;
875 			continue;
876 		}
877 		bh[i] = ext4_read_block_bitmap_nowait(sb, group);
878 		if (IS_ERR(bh[i])) {
879 			err = PTR_ERR(bh[i]);
880 			bh[i] = NULL;
881 			goto out;
882 		}
883 		mb_debug(1, "read bitmap for group %u\n", group);
884 	}
885 
886 	/* wait for I/O completion */
887 	for (i = 0, group = first_group; i < groups_per_page; i++, group++) {
888 		int err2;
889 
890 		if (!bh[i])
891 			continue;
892 		err2 = ext4_wait_block_bitmap(sb, group, bh[i]);
893 		if (!err)
894 			err = err2;
895 	}
896 
897 	first_block = page->index * blocks_per_page;
898 	for (i = 0; i < blocks_per_page; i++) {
899 		group = (first_block + i) >> 1;
900 		if (group >= ngroups)
901 			break;
902 
903 		if (!bh[group - first_group])
904 			/* skip initialized uptodate buddy */
905 			continue;
906 
907 		if (!buffer_verified(bh[group - first_group]))
908 			/* Skip faulty bitmaps */
909 			continue;
910 		err = 0;
911 
912 		/*
913 		 * data carry information regarding this
914 		 * particular group in the format specified
915 		 * above
916 		 *
917 		 */
918 		data = page_address(page) + (i * blocksize);
919 		bitmap = bh[group - first_group]->b_data;
920 
921 		/*
922 		 * We place the buddy block and bitmap block
923 		 * close together
924 		 */
925 		if ((first_block + i) & 1) {
926 			/* this is block of buddy */
927 			BUG_ON(incore == NULL);
928 			mb_debug(1, "put buddy for group %u in page %lu/%x\n",
929 				group, page->index, i * blocksize);
930 			trace_ext4_mb_buddy_bitmap_load(sb, group);
931 			grinfo = ext4_get_group_info(sb, group);
932 			grinfo->bb_fragments = 0;
933 			memset(grinfo->bb_counters, 0,
934 			       sizeof(*grinfo->bb_counters) *
935 				(sb->s_blocksize_bits+2));
936 			/*
937 			 * incore got set to the group block bitmap below
938 			 */
939 			ext4_lock_group(sb, group);
940 			/* init the buddy */
941 			memset(data, 0xff, blocksize);
942 			ext4_mb_generate_buddy(sb, data, incore, group);
943 			ext4_unlock_group(sb, group);
944 			incore = NULL;
945 		} else {
946 			/* this is block of bitmap */
947 			BUG_ON(incore != NULL);
948 			mb_debug(1, "put bitmap for group %u in page %lu/%x\n",
949 				group, page->index, i * blocksize);
950 			trace_ext4_mb_bitmap_load(sb, group);
951 
952 			/* see comments in ext4_mb_put_pa() */
953 			ext4_lock_group(sb, group);
954 			memcpy(data, bitmap, blocksize);
955 
956 			/* mark all preallocated blks used in in-core bitmap */
957 			ext4_mb_generate_from_pa(sb, data, group);
958 			ext4_mb_generate_from_freelist(sb, data, group);
959 			ext4_unlock_group(sb, group);
960 
961 			/* set incore so that the buddy information can be
962 			 * generated using this
963 			 */
964 			incore = data;
965 		}
966 	}
967 	SetPageUptodate(page);
968 
969 out:
970 	if (bh) {
971 		for (i = 0; i < groups_per_page; i++)
972 			brelse(bh[i]);
973 		if (bh != &bhs)
974 			kfree(bh);
975 	}
976 	return err;
977 }
978 
979 /*
980  * Lock the buddy and bitmap pages. This make sure other parallel init_group
981  * on the same buddy page doesn't happen whild holding the buddy page lock.
982  * Return locked buddy and bitmap pages on e4b struct. If buddy and bitmap
983  * are on the same page e4b->bd_buddy_page is NULL and return value is 0.
984  */
985 static int ext4_mb_get_buddy_page_lock(struct super_block *sb,
986 		ext4_group_t group, struct ext4_buddy *e4b, gfp_t gfp)
987 {
988 	struct inode *inode = EXT4_SB(sb)->s_buddy_cache;
989 	int block, pnum, poff;
990 	int blocks_per_page;
991 	struct page *page;
992 
993 	e4b->bd_buddy_page = NULL;
994 	e4b->bd_bitmap_page = NULL;
995 
996 	blocks_per_page = PAGE_SIZE / sb->s_blocksize;
997 	/*
998 	 * the buddy cache inode stores the block bitmap
999 	 * and buddy information in consecutive blocks.
1000 	 * So for each group we need two blocks.
1001 	 */
1002 	block = group * 2;
1003 	pnum = block / blocks_per_page;
1004 	poff = block % blocks_per_page;
1005 	page = find_or_create_page(inode->i_mapping, pnum, gfp);
1006 	if (!page)
1007 		return -ENOMEM;
1008 	BUG_ON(page->mapping != inode->i_mapping);
1009 	e4b->bd_bitmap_page = page;
1010 	e4b->bd_bitmap = page_address(page) + (poff * sb->s_blocksize);
1011 
1012 	if (blocks_per_page >= 2) {
1013 		/* buddy and bitmap are on the same page */
1014 		return 0;
1015 	}
1016 
1017 	block++;
1018 	pnum = block / blocks_per_page;
1019 	page = find_or_create_page(inode->i_mapping, pnum, gfp);
1020 	if (!page)
1021 		return -ENOMEM;
1022 	BUG_ON(page->mapping != inode->i_mapping);
1023 	e4b->bd_buddy_page = page;
1024 	return 0;
1025 }
1026 
1027 static void ext4_mb_put_buddy_page_lock(struct ext4_buddy *e4b)
1028 {
1029 	if (e4b->bd_bitmap_page) {
1030 		unlock_page(e4b->bd_bitmap_page);
1031 		put_page(e4b->bd_bitmap_page);
1032 	}
1033 	if (e4b->bd_buddy_page) {
1034 		unlock_page(e4b->bd_buddy_page);
1035 		put_page(e4b->bd_buddy_page);
1036 	}
1037 }
1038 
1039 /*
1040  * Locking note:  This routine calls ext4_mb_init_cache(), which takes the
1041  * block group lock of all groups for this page; do not hold the BG lock when
1042  * calling this routine!
1043  */
1044 static noinline_for_stack
1045 int ext4_mb_init_group(struct super_block *sb, ext4_group_t group, gfp_t gfp)
1046 {
1047 
1048 	struct ext4_group_info *this_grp;
1049 	struct ext4_buddy e4b;
1050 	struct page *page;
1051 	int ret = 0;
1052 
1053 	might_sleep();
1054 	mb_debug(1, "init group %u\n", group);
1055 	this_grp = ext4_get_group_info(sb, group);
1056 	/*
1057 	 * This ensures that we don't reinit the buddy cache
1058 	 * page which map to the group from which we are already
1059 	 * allocating. If we are looking at the buddy cache we would
1060 	 * have taken a reference using ext4_mb_load_buddy and that
1061 	 * would have pinned buddy page to page cache.
1062 	 * The call to ext4_mb_get_buddy_page_lock will mark the
1063 	 * page accessed.
1064 	 */
1065 	ret = ext4_mb_get_buddy_page_lock(sb, group, &e4b, gfp);
1066 	if (ret || !EXT4_MB_GRP_NEED_INIT(this_grp)) {
1067 		/*
1068 		 * somebody initialized the group
1069 		 * return without doing anything
1070 		 */
1071 		goto err;
1072 	}
1073 
1074 	page = e4b.bd_bitmap_page;
1075 	ret = ext4_mb_init_cache(page, NULL, gfp);
1076 	if (ret)
1077 		goto err;
1078 	if (!PageUptodate(page)) {
1079 		ret = -EIO;
1080 		goto err;
1081 	}
1082 
1083 	if (e4b.bd_buddy_page == NULL) {
1084 		/*
1085 		 * If both the bitmap and buddy are in
1086 		 * the same page we don't need to force
1087 		 * init the buddy
1088 		 */
1089 		ret = 0;
1090 		goto err;
1091 	}
1092 	/* init buddy cache */
1093 	page = e4b.bd_buddy_page;
1094 	ret = ext4_mb_init_cache(page, e4b.bd_bitmap, gfp);
1095 	if (ret)
1096 		goto err;
1097 	if (!PageUptodate(page)) {
1098 		ret = -EIO;
1099 		goto err;
1100 	}
1101 err:
1102 	ext4_mb_put_buddy_page_lock(&e4b);
1103 	return ret;
1104 }
1105 
1106 /*
1107  * Locking note:  This routine calls ext4_mb_init_cache(), which takes the
1108  * block group lock of all groups for this page; do not hold the BG lock when
1109  * calling this routine!
1110  */
1111 static noinline_for_stack int
1112 ext4_mb_load_buddy_gfp(struct super_block *sb, ext4_group_t group,
1113 		       struct ext4_buddy *e4b, gfp_t gfp)
1114 {
1115 	int blocks_per_page;
1116 	int block;
1117 	int pnum;
1118 	int poff;
1119 	struct page *page;
1120 	int ret;
1121 	struct ext4_group_info *grp;
1122 	struct ext4_sb_info *sbi = EXT4_SB(sb);
1123 	struct inode *inode = sbi->s_buddy_cache;
1124 
1125 	might_sleep();
1126 	mb_debug(1, "load group %u\n", group);
1127 
1128 	blocks_per_page = PAGE_SIZE / sb->s_blocksize;
1129 	grp = ext4_get_group_info(sb, group);
1130 
1131 	e4b->bd_blkbits = sb->s_blocksize_bits;
1132 	e4b->bd_info = grp;
1133 	e4b->bd_sb = sb;
1134 	e4b->bd_group = group;
1135 	e4b->bd_buddy_page = NULL;
1136 	e4b->bd_bitmap_page = NULL;
1137 
1138 	if (unlikely(EXT4_MB_GRP_NEED_INIT(grp))) {
1139 		/*
1140 		 * we need full data about the group
1141 		 * to make a good selection
1142 		 */
1143 		ret = ext4_mb_init_group(sb, group, gfp);
1144 		if (ret)
1145 			return ret;
1146 	}
1147 
1148 	/*
1149 	 * the buddy cache inode stores the block bitmap
1150 	 * and buddy information in consecutive blocks.
1151 	 * So for each group we need two blocks.
1152 	 */
1153 	block = group * 2;
1154 	pnum = block / blocks_per_page;
1155 	poff = block % blocks_per_page;
1156 
1157 	/* we could use find_or_create_page(), but it locks page
1158 	 * what we'd like to avoid in fast path ... */
1159 	page = find_get_page_flags(inode->i_mapping, pnum, FGP_ACCESSED);
1160 	if (page == NULL || !PageUptodate(page)) {
1161 		if (page)
1162 			/*
1163 			 * drop the page reference and try
1164 			 * to get the page with lock. If we
1165 			 * are not uptodate that implies
1166 			 * somebody just created the page but
1167 			 * is yet to initialize the same. So
1168 			 * wait for it to initialize.
1169 			 */
1170 			put_page(page);
1171 		page = find_or_create_page(inode->i_mapping, pnum, gfp);
1172 		if (page) {
1173 			BUG_ON(page->mapping != inode->i_mapping);
1174 			if (!PageUptodate(page)) {
1175 				ret = ext4_mb_init_cache(page, NULL, gfp);
1176 				if (ret) {
1177 					unlock_page(page);
1178 					goto err;
1179 				}
1180 				mb_cmp_bitmaps(e4b, page_address(page) +
1181 					       (poff * sb->s_blocksize));
1182 			}
1183 			unlock_page(page);
1184 		}
1185 	}
1186 	if (page == NULL) {
1187 		ret = -ENOMEM;
1188 		goto err;
1189 	}
1190 	if (!PageUptodate(page)) {
1191 		ret = -EIO;
1192 		goto err;
1193 	}
1194 
1195 	/* Pages marked accessed already */
1196 	e4b->bd_bitmap_page = page;
1197 	e4b->bd_bitmap = page_address(page) + (poff * sb->s_blocksize);
1198 
1199 	block++;
1200 	pnum = block / blocks_per_page;
1201 	poff = block % blocks_per_page;
1202 
1203 	page = find_get_page_flags(inode->i_mapping, pnum, FGP_ACCESSED);
1204 	if (page == NULL || !PageUptodate(page)) {
1205 		if (page)
1206 			put_page(page);
1207 		page = find_or_create_page(inode->i_mapping, pnum, gfp);
1208 		if (page) {
1209 			BUG_ON(page->mapping != inode->i_mapping);
1210 			if (!PageUptodate(page)) {
1211 				ret = ext4_mb_init_cache(page, e4b->bd_bitmap,
1212 							 gfp);
1213 				if (ret) {
1214 					unlock_page(page);
1215 					goto err;
1216 				}
1217 			}
1218 			unlock_page(page);
1219 		}
1220 	}
1221 	if (page == NULL) {
1222 		ret = -ENOMEM;
1223 		goto err;
1224 	}
1225 	if (!PageUptodate(page)) {
1226 		ret = -EIO;
1227 		goto err;
1228 	}
1229 
1230 	/* Pages marked accessed already */
1231 	e4b->bd_buddy_page = page;
1232 	e4b->bd_buddy = page_address(page) + (poff * sb->s_blocksize);
1233 
1234 	BUG_ON(e4b->bd_bitmap_page == NULL);
1235 	BUG_ON(e4b->bd_buddy_page == NULL);
1236 
1237 	return 0;
1238 
1239 err:
1240 	if (page)
1241 		put_page(page);
1242 	if (e4b->bd_bitmap_page)
1243 		put_page(e4b->bd_bitmap_page);
1244 	if (e4b->bd_buddy_page)
1245 		put_page(e4b->bd_buddy_page);
1246 	e4b->bd_buddy = NULL;
1247 	e4b->bd_bitmap = NULL;
1248 	return ret;
1249 }
1250 
1251 static int ext4_mb_load_buddy(struct super_block *sb, ext4_group_t group,
1252 			      struct ext4_buddy *e4b)
1253 {
1254 	return ext4_mb_load_buddy_gfp(sb, group, e4b, GFP_NOFS);
1255 }
1256 
1257 static void ext4_mb_unload_buddy(struct ext4_buddy *e4b)
1258 {
1259 	if (e4b->bd_bitmap_page)
1260 		put_page(e4b->bd_bitmap_page);
1261 	if (e4b->bd_buddy_page)
1262 		put_page(e4b->bd_buddy_page);
1263 }
1264 
1265 
1266 static int mb_find_order_for_block(struct ext4_buddy *e4b, int block)
1267 {
1268 	int order = 1;
1269 	int bb_incr = 1 << (e4b->bd_blkbits - 1);
1270 	void *bb;
1271 
1272 	BUG_ON(e4b->bd_bitmap == e4b->bd_buddy);
1273 	BUG_ON(block >= (1 << (e4b->bd_blkbits + 3)));
1274 
1275 	bb = e4b->bd_buddy;
1276 	while (order <= e4b->bd_blkbits + 1) {
1277 		block = block >> 1;
1278 		if (!mb_test_bit(block, bb)) {
1279 			/* this block is part of buddy of order 'order' */
1280 			return order;
1281 		}
1282 		bb += bb_incr;
1283 		bb_incr >>= 1;
1284 		order++;
1285 	}
1286 	return 0;
1287 }
1288 
1289 static void mb_clear_bits(void *bm, int cur, int len)
1290 {
1291 	__u32 *addr;
1292 
1293 	len = cur + len;
1294 	while (cur < len) {
1295 		if ((cur & 31) == 0 && (len - cur) >= 32) {
1296 			/* fast path: clear whole word at once */
1297 			addr = bm + (cur >> 3);
1298 			*addr = 0;
1299 			cur += 32;
1300 			continue;
1301 		}
1302 		mb_clear_bit(cur, bm);
1303 		cur++;
1304 	}
1305 }
1306 
1307 /* clear bits in given range
1308  * will return first found zero bit if any, -1 otherwise
1309  */
1310 static int mb_test_and_clear_bits(void *bm, int cur, int len)
1311 {
1312 	__u32 *addr;
1313 	int zero_bit = -1;
1314 
1315 	len = cur + len;
1316 	while (cur < len) {
1317 		if ((cur & 31) == 0 && (len - cur) >= 32) {
1318 			/* fast path: clear whole word at once */
1319 			addr = bm + (cur >> 3);
1320 			if (*addr != (__u32)(-1) && zero_bit == -1)
1321 				zero_bit = cur + mb_find_next_zero_bit(addr, 32, 0);
1322 			*addr = 0;
1323 			cur += 32;
1324 			continue;
1325 		}
1326 		if (!mb_test_and_clear_bit(cur, bm) && zero_bit == -1)
1327 			zero_bit = cur;
1328 		cur++;
1329 	}
1330 
1331 	return zero_bit;
1332 }
1333 
1334 void ext4_set_bits(void *bm, int cur, int len)
1335 {
1336 	__u32 *addr;
1337 
1338 	len = cur + len;
1339 	while (cur < len) {
1340 		if ((cur & 31) == 0 && (len - cur) >= 32) {
1341 			/* fast path: set whole word at once */
1342 			addr = bm + (cur >> 3);
1343 			*addr = 0xffffffff;
1344 			cur += 32;
1345 			continue;
1346 		}
1347 		mb_set_bit(cur, bm);
1348 		cur++;
1349 	}
1350 }
1351 
1352 /*
1353  * _________________________________________________________________ */
1354 
1355 static inline int mb_buddy_adjust_border(int* bit, void* bitmap, int side)
1356 {
1357 	if (mb_test_bit(*bit + side, bitmap)) {
1358 		mb_clear_bit(*bit, bitmap);
1359 		(*bit) -= side;
1360 		return 1;
1361 	}
1362 	else {
1363 		(*bit) += side;
1364 		mb_set_bit(*bit, bitmap);
1365 		return -1;
1366 	}
1367 }
1368 
1369 static void mb_buddy_mark_free(struct ext4_buddy *e4b, int first, int last)
1370 {
1371 	int max;
1372 	int order = 1;
1373 	void *buddy = mb_find_buddy(e4b, order, &max);
1374 
1375 	while (buddy) {
1376 		void *buddy2;
1377 
1378 		/* Bits in range [first; last] are known to be set since
1379 		 * corresponding blocks were allocated. Bits in range
1380 		 * (first; last) will stay set because they form buddies on
1381 		 * upper layer. We just deal with borders if they don't
1382 		 * align with upper layer and then go up.
1383 		 * Releasing entire group is all about clearing
1384 		 * single bit of highest order buddy.
1385 		 */
1386 
1387 		/* Example:
1388 		 * ---------------------------------
1389 		 * |   1   |   1   |   1   |   1   |
1390 		 * ---------------------------------
1391 		 * | 0 | 1 | 1 | 1 | 1 | 1 | 1 | 1 |
1392 		 * ---------------------------------
1393 		 *   0   1   2   3   4   5   6   7
1394 		 *      \_____________________/
1395 		 *
1396 		 * Neither [1] nor [6] is aligned to above layer.
1397 		 * Left neighbour [0] is free, so mark it busy,
1398 		 * decrease bb_counters and extend range to
1399 		 * [0; 6]
1400 		 * Right neighbour [7] is busy. It can't be coaleasced with [6], so
1401 		 * mark [6] free, increase bb_counters and shrink range to
1402 		 * [0; 5].
1403 		 * Then shift range to [0; 2], go up and do the same.
1404 		 */
1405 
1406 
1407 		if (first & 1)
1408 			e4b->bd_info->bb_counters[order] += mb_buddy_adjust_border(&first, buddy, -1);
1409 		if (!(last & 1))
1410 			e4b->bd_info->bb_counters[order] += mb_buddy_adjust_border(&last, buddy, 1);
1411 		if (first > last)
1412 			break;
1413 		order++;
1414 
1415 		if (first == last || !(buddy2 = mb_find_buddy(e4b, order, &max))) {
1416 			mb_clear_bits(buddy, first, last - first + 1);
1417 			e4b->bd_info->bb_counters[order - 1] += last - first + 1;
1418 			break;
1419 		}
1420 		first >>= 1;
1421 		last >>= 1;
1422 		buddy = buddy2;
1423 	}
1424 }
1425 
1426 static void mb_free_blocks(struct inode *inode, struct ext4_buddy *e4b,
1427 			   int first, int count)
1428 {
1429 	int left_is_free = 0;
1430 	int right_is_free = 0;
1431 	int block;
1432 	int last = first + count - 1;
1433 	struct super_block *sb = e4b->bd_sb;
1434 
1435 	if (WARN_ON(count == 0))
1436 		return;
1437 	BUG_ON(last >= (sb->s_blocksize << 3));
1438 	assert_spin_locked(ext4_group_lock_ptr(sb, e4b->bd_group));
1439 	/* Don't bother if the block group is corrupt. */
1440 	if (unlikely(EXT4_MB_GRP_BBITMAP_CORRUPT(e4b->bd_info)))
1441 		return;
1442 
1443 	mb_check_buddy(e4b);
1444 	mb_free_blocks_double(inode, e4b, first, count);
1445 
1446 	e4b->bd_info->bb_free += count;
1447 	if (first < e4b->bd_info->bb_first_free)
1448 		e4b->bd_info->bb_first_free = first;
1449 
1450 	/* access memory sequentially: check left neighbour,
1451 	 * clear range and then check right neighbour
1452 	 */
1453 	if (first != 0)
1454 		left_is_free = !mb_test_bit(first - 1, e4b->bd_bitmap);
1455 	block = mb_test_and_clear_bits(e4b->bd_bitmap, first, count);
1456 	if (last + 1 < EXT4_SB(sb)->s_mb_maxs[0])
1457 		right_is_free = !mb_test_bit(last + 1, e4b->bd_bitmap);
1458 
1459 	if (unlikely(block != -1)) {
1460 		struct ext4_sb_info *sbi = EXT4_SB(sb);
1461 		ext4_fsblk_t blocknr;
1462 
1463 		blocknr = ext4_group_first_block_no(sb, e4b->bd_group);
1464 		blocknr += EXT4_C2B(EXT4_SB(sb), block);
1465 		ext4_grp_locked_error(sb, e4b->bd_group,
1466 				      inode ? inode->i_ino : 0,
1467 				      blocknr,
1468 				      "freeing already freed block "
1469 				      "(bit %u); block bitmap corrupt.",
1470 				      block);
1471 		if (!EXT4_MB_GRP_BBITMAP_CORRUPT(e4b->bd_info))
1472 			percpu_counter_sub(&sbi->s_freeclusters_counter,
1473 					   e4b->bd_info->bb_free);
1474 		/* Mark the block group as corrupt. */
1475 		set_bit(EXT4_GROUP_INFO_BBITMAP_CORRUPT_BIT,
1476 			&e4b->bd_info->bb_state);
1477 		mb_regenerate_buddy(e4b);
1478 		goto done;
1479 	}
1480 
1481 	/* let's maintain fragments counter */
1482 	if (left_is_free && right_is_free)
1483 		e4b->bd_info->bb_fragments--;
1484 	else if (!left_is_free && !right_is_free)
1485 		e4b->bd_info->bb_fragments++;
1486 
1487 	/* buddy[0] == bd_bitmap is a special case, so handle
1488 	 * it right away and let mb_buddy_mark_free stay free of
1489 	 * zero order checks.
1490 	 * Check if neighbours are to be coaleasced,
1491 	 * adjust bitmap bb_counters and borders appropriately.
1492 	 */
1493 	if (first & 1) {
1494 		first += !left_is_free;
1495 		e4b->bd_info->bb_counters[0] += left_is_free ? -1 : 1;
1496 	}
1497 	if (!(last & 1)) {
1498 		last -= !right_is_free;
1499 		e4b->bd_info->bb_counters[0] += right_is_free ? -1 : 1;
1500 	}
1501 
1502 	if (first <= last)
1503 		mb_buddy_mark_free(e4b, first >> 1, last >> 1);
1504 
1505 done:
1506 	mb_set_largest_free_order(sb, e4b->bd_info);
1507 	mb_check_buddy(e4b);
1508 }
1509 
1510 static int mb_find_extent(struct ext4_buddy *e4b, int block,
1511 				int needed, struct ext4_free_extent *ex)
1512 {
1513 	int next = block;
1514 	int max, order;
1515 	void *buddy;
1516 
1517 	assert_spin_locked(ext4_group_lock_ptr(e4b->bd_sb, e4b->bd_group));
1518 	BUG_ON(ex == NULL);
1519 
1520 	buddy = mb_find_buddy(e4b, 0, &max);
1521 	BUG_ON(buddy == NULL);
1522 	BUG_ON(block >= max);
1523 	if (mb_test_bit(block, buddy)) {
1524 		ex->fe_len = 0;
1525 		ex->fe_start = 0;
1526 		ex->fe_group = 0;
1527 		return 0;
1528 	}
1529 
1530 	/* find actual order */
1531 	order = mb_find_order_for_block(e4b, block);
1532 	block = block >> order;
1533 
1534 	ex->fe_len = 1 << order;
1535 	ex->fe_start = block << order;
1536 	ex->fe_group = e4b->bd_group;
1537 
1538 	/* calc difference from given start */
1539 	next = next - ex->fe_start;
1540 	ex->fe_len -= next;
1541 	ex->fe_start += next;
1542 
1543 	while (needed > ex->fe_len &&
1544 	       mb_find_buddy(e4b, order, &max)) {
1545 
1546 		if (block + 1 >= max)
1547 			break;
1548 
1549 		next = (block + 1) * (1 << order);
1550 		if (mb_test_bit(next, e4b->bd_bitmap))
1551 			break;
1552 
1553 		order = mb_find_order_for_block(e4b, next);
1554 
1555 		block = next >> order;
1556 		ex->fe_len += 1 << order;
1557 	}
1558 
1559 	if (ex->fe_start + ex->fe_len > (1 << (e4b->bd_blkbits + 3))) {
1560 		/* Should never happen! (but apparently sometimes does?!?) */
1561 		WARN_ON(1);
1562 		ext4_error(e4b->bd_sb, "corruption or bug in mb_find_extent "
1563 			   "block=%d, order=%d needed=%d ex=%u/%d/%d@%u",
1564 			   block, order, needed, ex->fe_group, ex->fe_start,
1565 			   ex->fe_len, ex->fe_logical);
1566 		ex->fe_len = 0;
1567 		ex->fe_start = 0;
1568 		ex->fe_group = 0;
1569 	}
1570 	return ex->fe_len;
1571 }
1572 
1573 static int mb_mark_used(struct ext4_buddy *e4b, struct ext4_free_extent *ex)
1574 {
1575 	int ord;
1576 	int mlen = 0;
1577 	int max = 0;
1578 	int cur;
1579 	int start = ex->fe_start;
1580 	int len = ex->fe_len;
1581 	unsigned ret = 0;
1582 	int len0 = len;
1583 	void *buddy;
1584 
1585 	BUG_ON(start + len > (e4b->bd_sb->s_blocksize << 3));
1586 	BUG_ON(e4b->bd_group != ex->fe_group);
1587 	assert_spin_locked(ext4_group_lock_ptr(e4b->bd_sb, e4b->bd_group));
1588 	mb_check_buddy(e4b);
1589 	mb_mark_used_double(e4b, start, len);
1590 
1591 	e4b->bd_info->bb_free -= len;
1592 	if (e4b->bd_info->bb_first_free == start)
1593 		e4b->bd_info->bb_first_free += len;
1594 
1595 	/* let's maintain fragments counter */
1596 	if (start != 0)
1597 		mlen = !mb_test_bit(start - 1, e4b->bd_bitmap);
1598 	if (start + len < EXT4_SB(e4b->bd_sb)->s_mb_maxs[0])
1599 		max = !mb_test_bit(start + len, e4b->bd_bitmap);
1600 	if (mlen && max)
1601 		e4b->bd_info->bb_fragments++;
1602 	else if (!mlen && !max)
1603 		e4b->bd_info->bb_fragments--;
1604 
1605 	/* let's maintain buddy itself */
1606 	while (len) {
1607 		ord = mb_find_order_for_block(e4b, start);
1608 
1609 		if (((start >> ord) << ord) == start && len >= (1 << ord)) {
1610 			/* the whole chunk may be allocated at once! */
1611 			mlen = 1 << ord;
1612 			buddy = mb_find_buddy(e4b, ord, &max);
1613 			BUG_ON((start >> ord) >= max);
1614 			mb_set_bit(start >> ord, buddy);
1615 			e4b->bd_info->bb_counters[ord]--;
1616 			start += mlen;
1617 			len -= mlen;
1618 			BUG_ON(len < 0);
1619 			continue;
1620 		}
1621 
1622 		/* store for history */
1623 		if (ret == 0)
1624 			ret = len | (ord << 16);
1625 
1626 		/* we have to split large buddy */
1627 		BUG_ON(ord <= 0);
1628 		buddy = mb_find_buddy(e4b, ord, &max);
1629 		mb_set_bit(start >> ord, buddy);
1630 		e4b->bd_info->bb_counters[ord]--;
1631 
1632 		ord--;
1633 		cur = (start >> ord) & ~1U;
1634 		buddy = mb_find_buddy(e4b, ord, &max);
1635 		mb_clear_bit(cur, buddy);
1636 		mb_clear_bit(cur + 1, buddy);
1637 		e4b->bd_info->bb_counters[ord]++;
1638 		e4b->bd_info->bb_counters[ord]++;
1639 	}
1640 	mb_set_largest_free_order(e4b->bd_sb, e4b->bd_info);
1641 
1642 	ext4_set_bits(e4b->bd_bitmap, ex->fe_start, len0);
1643 	mb_check_buddy(e4b);
1644 
1645 	return ret;
1646 }
1647 
1648 /*
1649  * Must be called under group lock!
1650  */
1651 static void ext4_mb_use_best_found(struct ext4_allocation_context *ac,
1652 					struct ext4_buddy *e4b)
1653 {
1654 	struct ext4_sb_info *sbi = EXT4_SB(ac->ac_sb);
1655 	int ret;
1656 
1657 	BUG_ON(ac->ac_b_ex.fe_group != e4b->bd_group);
1658 	BUG_ON(ac->ac_status == AC_STATUS_FOUND);
1659 
1660 	ac->ac_b_ex.fe_len = min(ac->ac_b_ex.fe_len, ac->ac_g_ex.fe_len);
1661 	ac->ac_b_ex.fe_logical = ac->ac_g_ex.fe_logical;
1662 	ret = mb_mark_used(e4b, &ac->ac_b_ex);
1663 
1664 	/* preallocation can change ac_b_ex, thus we store actually
1665 	 * allocated blocks for history */
1666 	ac->ac_f_ex = ac->ac_b_ex;
1667 
1668 	ac->ac_status = AC_STATUS_FOUND;
1669 	ac->ac_tail = ret & 0xffff;
1670 	ac->ac_buddy = ret >> 16;
1671 
1672 	/*
1673 	 * take the page reference. We want the page to be pinned
1674 	 * so that we don't get a ext4_mb_init_cache_call for this
1675 	 * group until we update the bitmap. That would mean we
1676 	 * double allocate blocks. The reference is dropped
1677 	 * in ext4_mb_release_context
1678 	 */
1679 	ac->ac_bitmap_page = e4b->bd_bitmap_page;
1680 	get_page(ac->ac_bitmap_page);
1681 	ac->ac_buddy_page = e4b->bd_buddy_page;
1682 	get_page(ac->ac_buddy_page);
1683 	/* store last allocated for subsequent stream allocation */
1684 	if (ac->ac_flags & EXT4_MB_STREAM_ALLOC) {
1685 		spin_lock(&sbi->s_md_lock);
1686 		sbi->s_mb_last_group = ac->ac_f_ex.fe_group;
1687 		sbi->s_mb_last_start = ac->ac_f_ex.fe_start;
1688 		spin_unlock(&sbi->s_md_lock);
1689 	}
1690 }
1691 
1692 /*
1693  * regular allocator, for general purposes allocation
1694  */
1695 
1696 static void ext4_mb_check_limits(struct ext4_allocation_context *ac,
1697 					struct ext4_buddy *e4b,
1698 					int finish_group)
1699 {
1700 	struct ext4_sb_info *sbi = EXT4_SB(ac->ac_sb);
1701 	struct ext4_free_extent *bex = &ac->ac_b_ex;
1702 	struct ext4_free_extent *gex = &ac->ac_g_ex;
1703 	struct ext4_free_extent ex;
1704 	int max;
1705 
1706 	if (ac->ac_status == AC_STATUS_FOUND)
1707 		return;
1708 	/*
1709 	 * We don't want to scan for a whole year
1710 	 */
1711 	if (ac->ac_found > sbi->s_mb_max_to_scan &&
1712 			!(ac->ac_flags & EXT4_MB_HINT_FIRST)) {
1713 		ac->ac_status = AC_STATUS_BREAK;
1714 		return;
1715 	}
1716 
1717 	/*
1718 	 * Haven't found good chunk so far, let's continue
1719 	 */
1720 	if (bex->fe_len < gex->fe_len)
1721 		return;
1722 
1723 	if ((finish_group || ac->ac_found > sbi->s_mb_min_to_scan)
1724 			&& bex->fe_group == e4b->bd_group) {
1725 		/* recheck chunk's availability - we don't know
1726 		 * when it was found (within this lock-unlock
1727 		 * period or not) */
1728 		max = mb_find_extent(e4b, bex->fe_start, gex->fe_len, &ex);
1729 		if (max >= gex->fe_len) {
1730 			ext4_mb_use_best_found(ac, e4b);
1731 			return;
1732 		}
1733 	}
1734 }
1735 
1736 /*
1737  * The routine checks whether found extent is good enough. If it is,
1738  * then the extent gets marked used and flag is set to the context
1739  * to stop scanning. Otherwise, the extent is compared with the
1740  * previous found extent and if new one is better, then it's stored
1741  * in the context. Later, the best found extent will be used, if
1742  * mballoc can't find good enough extent.
1743  *
1744  * FIXME: real allocation policy is to be designed yet!
1745  */
1746 static void ext4_mb_measure_extent(struct ext4_allocation_context *ac,
1747 					struct ext4_free_extent *ex,
1748 					struct ext4_buddy *e4b)
1749 {
1750 	struct ext4_free_extent *bex = &ac->ac_b_ex;
1751 	struct ext4_free_extent *gex = &ac->ac_g_ex;
1752 
1753 	BUG_ON(ex->fe_len <= 0);
1754 	BUG_ON(ex->fe_len > EXT4_CLUSTERS_PER_GROUP(ac->ac_sb));
1755 	BUG_ON(ex->fe_start >= EXT4_CLUSTERS_PER_GROUP(ac->ac_sb));
1756 	BUG_ON(ac->ac_status != AC_STATUS_CONTINUE);
1757 
1758 	ac->ac_found++;
1759 
1760 	/*
1761 	 * The special case - take what you catch first
1762 	 */
1763 	if (unlikely(ac->ac_flags & EXT4_MB_HINT_FIRST)) {
1764 		*bex = *ex;
1765 		ext4_mb_use_best_found(ac, e4b);
1766 		return;
1767 	}
1768 
1769 	/*
1770 	 * Let's check whether the chuck is good enough
1771 	 */
1772 	if (ex->fe_len == gex->fe_len) {
1773 		*bex = *ex;
1774 		ext4_mb_use_best_found(ac, e4b);
1775 		return;
1776 	}
1777 
1778 	/*
1779 	 * If this is first found extent, just store it in the context
1780 	 */
1781 	if (bex->fe_len == 0) {
1782 		*bex = *ex;
1783 		return;
1784 	}
1785 
1786 	/*
1787 	 * If new found extent is better, store it in the context
1788 	 */
1789 	if (bex->fe_len < gex->fe_len) {
1790 		/* if the request isn't satisfied, any found extent
1791 		 * larger than previous best one is better */
1792 		if (ex->fe_len > bex->fe_len)
1793 			*bex = *ex;
1794 	} else if (ex->fe_len > gex->fe_len) {
1795 		/* if the request is satisfied, then we try to find
1796 		 * an extent that still satisfy the request, but is
1797 		 * smaller than previous one */
1798 		if (ex->fe_len < bex->fe_len)
1799 			*bex = *ex;
1800 	}
1801 
1802 	ext4_mb_check_limits(ac, e4b, 0);
1803 }
1804 
1805 static noinline_for_stack
1806 int ext4_mb_try_best_found(struct ext4_allocation_context *ac,
1807 					struct ext4_buddy *e4b)
1808 {
1809 	struct ext4_free_extent ex = ac->ac_b_ex;
1810 	ext4_group_t group = ex.fe_group;
1811 	int max;
1812 	int err;
1813 
1814 	BUG_ON(ex.fe_len <= 0);
1815 	err = ext4_mb_load_buddy(ac->ac_sb, group, e4b);
1816 	if (err)
1817 		return err;
1818 
1819 	ext4_lock_group(ac->ac_sb, group);
1820 	max = mb_find_extent(e4b, ex.fe_start, ex.fe_len, &ex);
1821 
1822 	if (max > 0) {
1823 		ac->ac_b_ex = ex;
1824 		ext4_mb_use_best_found(ac, e4b);
1825 	}
1826 
1827 	ext4_unlock_group(ac->ac_sb, group);
1828 	ext4_mb_unload_buddy(e4b);
1829 
1830 	return 0;
1831 }
1832 
1833 static noinline_for_stack
1834 int ext4_mb_find_by_goal(struct ext4_allocation_context *ac,
1835 				struct ext4_buddy *e4b)
1836 {
1837 	ext4_group_t group = ac->ac_g_ex.fe_group;
1838 	int max;
1839 	int err;
1840 	struct ext4_sb_info *sbi = EXT4_SB(ac->ac_sb);
1841 	struct ext4_group_info *grp = ext4_get_group_info(ac->ac_sb, group);
1842 	struct ext4_free_extent ex;
1843 
1844 	if (!(ac->ac_flags & EXT4_MB_HINT_TRY_GOAL))
1845 		return 0;
1846 	if (grp->bb_free == 0)
1847 		return 0;
1848 
1849 	err = ext4_mb_load_buddy(ac->ac_sb, group, e4b);
1850 	if (err)
1851 		return err;
1852 
1853 	if (unlikely(EXT4_MB_GRP_BBITMAP_CORRUPT(e4b->bd_info))) {
1854 		ext4_mb_unload_buddy(e4b);
1855 		return 0;
1856 	}
1857 
1858 	ext4_lock_group(ac->ac_sb, group);
1859 	max = mb_find_extent(e4b, ac->ac_g_ex.fe_start,
1860 			     ac->ac_g_ex.fe_len, &ex);
1861 	ex.fe_logical = 0xDEADFA11; /* debug value */
1862 
1863 	if (max >= ac->ac_g_ex.fe_len && ac->ac_g_ex.fe_len == sbi->s_stripe) {
1864 		ext4_fsblk_t start;
1865 
1866 		start = ext4_group_first_block_no(ac->ac_sb, e4b->bd_group) +
1867 			ex.fe_start;
1868 		/* use do_div to get remainder (would be 64-bit modulo) */
1869 		if (do_div(start, sbi->s_stripe) == 0) {
1870 			ac->ac_found++;
1871 			ac->ac_b_ex = ex;
1872 			ext4_mb_use_best_found(ac, e4b);
1873 		}
1874 	} else if (max >= ac->ac_g_ex.fe_len) {
1875 		BUG_ON(ex.fe_len <= 0);
1876 		BUG_ON(ex.fe_group != ac->ac_g_ex.fe_group);
1877 		BUG_ON(ex.fe_start != ac->ac_g_ex.fe_start);
1878 		ac->ac_found++;
1879 		ac->ac_b_ex = ex;
1880 		ext4_mb_use_best_found(ac, e4b);
1881 	} else if (max > 0 && (ac->ac_flags & EXT4_MB_HINT_MERGE)) {
1882 		/* Sometimes, caller may want to merge even small
1883 		 * number of blocks to an existing extent */
1884 		BUG_ON(ex.fe_len <= 0);
1885 		BUG_ON(ex.fe_group != ac->ac_g_ex.fe_group);
1886 		BUG_ON(ex.fe_start != ac->ac_g_ex.fe_start);
1887 		ac->ac_found++;
1888 		ac->ac_b_ex = ex;
1889 		ext4_mb_use_best_found(ac, e4b);
1890 	}
1891 	ext4_unlock_group(ac->ac_sb, group);
1892 	ext4_mb_unload_buddy(e4b);
1893 
1894 	return 0;
1895 }
1896 
1897 /*
1898  * The routine scans buddy structures (not bitmap!) from given order
1899  * to max order and tries to find big enough chunk to satisfy the req
1900  */
1901 static noinline_for_stack
1902 void ext4_mb_simple_scan_group(struct ext4_allocation_context *ac,
1903 					struct ext4_buddy *e4b)
1904 {
1905 	struct super_block *sb = ac->ac_sb;
1906 	struct ext4_group_info *grp = e4b->bd_info;
1907 	void *buddy;
1908 	int i;
1909 	int k;
1910 	int max;
1911 
1912 	BUG_ON(ac->ac_2order <= 0);
1913 	for (i = ac->ac_2order; i <= sb->s_blocksize_bits + 1; i++) {
1914 		if (grp->bb_counters[i] == 0)
1915 			continue;
1916 
1917 		buddy = mb_find_buddy(e4b, i, &max);
1918 		BUG_ON(buddy == NULL);
1919 
1920 		k = mb_find_next_zero_bit(buddy, max, 0);
1921 		BUG_ON(k >= max);
1922 
1923 		ac->ac_found++;
1924 
1925 		ac->ac_b_ex.fe_len = 1 << i;
1926 		ac->ac_b_ex.fe_start = k << i;
1927 		ac->ac_b_ex.fe_group = e4b->bd_group;
1928 
1929 		ext4_mb_use_best_found(ac, e4b);
1930 
1931 		BUG_ON(ac->ac_b_ex.fe_len != ac->ac_g_ex.fe_len);
1932 
1933 		if (EXT4_SB(sb)->s_mb_stats)
1934 			atomic_inc(&EXT4_SB(sb)->s_bal_2orders);
1935 
1936 		break;
1937 	}
1938 }
1939 
1940 /*
1941  * The routine scans the group and measures all found extents.
1942  * In order to optimize scanning, caller must pass number of
1943  * free blocks in the group, so the routine can know upper limit.
1944  */
1945 static noinline_for_stack
1946 void ext4_mb_complex_scan_group(struct ext4_allocation_context *ac,
1947 					struct ext4_buddy *e4b)
1948 {
1949 	struct super_block *sb = ac->ac_sb;
1950 	void *bitmap = e4b->bd_bitmap;
1951 	struct ext4_free_extent ex;
1952 	int i;
1953 	int free;
1954 
1955 	free = e4b->bd_info->bb_free;
1956 	BUG_ON(free <= 0);
1957 
1958 	i = e4b->bd_info->bb_first_free;
1959 
1960 	while (free && ac->ac_status == AC_STATUS_CONTINUE) {
1961 		i = mb_find_next_zero_bit(bitmap,
1962 						EXT4_CLUSTERS_PER_GROUP(sb), i);
1963 		if (i >= EXT4_CLUSTERS_PER_GROUP(sb)) {
1964 			/*
1965 			 * IF we have corrupt bitmap, we won't find any
1966 			 * free blocks even though group info says we
1967 			 * we have free blocks
1968 			 */
1969 			ext4_grp_locked_error(sb, e4b->bd_group, 0, 0,
1970 					"%d free clusters as per "
1971 					"group info. But bitmap says 0",
1972 					free);
1973 			break;
1974 		}
1975 
1976 		mb_find_extent(e4b, i, ac->ac_g_ex.fe_len, &ex);
1977 		BUG_ON(ex.fe_len <= 0);
1978 		if (free < ex.fe_len) {
1979 			ext4_grp_locked_error(sb, e4b->bd_group, 0, 0,
1980 					"%d free clusters as per "
1981 					"group info. But got %d blocks",
1982 					free, ex.fe_len);
1983 			/*
1984 			 * The number of free blocks differs. This mostly
1985 			 * indicate that the bitmap is corrupt. So exit
1986 			 * without claiming the space.
1987 			 */
1988 			break;
1989 		}
1990 		ex.fe_logical = 0xDEADC0DE; /* debug value */
1991 		ext4_mb_measure_extent(ac, &ex, e4b);
1992 
1993 		i += ex.fe_len;
1994 		free -= ex.fe_len;
1995 	}
1996 
1997 	ext4_mb_check_limits(ac, e4b, 1);
1998 }
1999 
2000 /*
2001  * This is a special case for storages like raid5
2002  * we try to find stripe-aligned chunks for stripe-size-multiple requests
2003  */
2004 static noinline_for_stack
2005 void ext4_mb_scan_aligned(struct ext4_allocation_context *ac,
2006 				 struct ext4_buddy *e4b)
2007 {
2008 	struct super_block *sb = ac->ac_sb;
2009 	struct ext4_sb_info *sbi = EXT4_SB(sb);
2010 	void *bitmap = e4b->bd_bitmap;
2011 	struct ext4_free_extent ex;
2012 	ext4_fsblk_t first_group_block;
2013 	ext4_fsblk_t a;
2014 	ext4_grpblk_t i;
2015 	int max;
2016 
2017 	BUG_ON(sbi->s_stripe == 0);
2018 
2019 	/* find first stripe-aligned block in group */
2020 	first_group_block = ext4_group_first_block_no(sb, e4b->bd_group);
2021 
2022 	a = first_group_block + sbi->s_stripe - 1;
2023 	do_div(a, sbi->s_stripe);
2024 	i = (a * sbi->s_stripe) - first_group_block;
2025 
2026 	while (i < EXT4_CLUSTERS_PER_GROUP(sb)) {
2027 		if (!mb_test_bit(i, bitmap)) {
2028 			max = mb_find_extent(e4b, i, sbi->s_stripe, &ex);
2029 			if (max >= sbi->s_stripe) {
2030 				ac->ac_found++;
2031 				ex.fe_logical = 0xDEADF00D; /* debug value */
2032 				ac->ac_b_ex = ex;
2033 				ext4_mb_use_best_found(ac, e4b);
2034 				break;
2035 			}
2036 		}
2037 		i += sbi->s_stripe;
2038 	}
2039 }
2040 
2041 /*
2042  * This is now called BEFORE we load the buddy bitmap.
2043  * Returns either 1 or 0 indicating that the group is either suitable
2044  * for the allocation or not. In addition it can also return negative
2045  * error code when something goes wrong.
2046  */
2047 static int ext4_mb_good_group(struct ext4_allocation_context *ac,
2048 				ext4_group_t group, int cr)
2049 {
2050 	unsigned free, fragments;
2051 	int flex_size = ext4_flex_bg_size(EXT4_SB(ac->ac_sb));
2052 	struct ext4_group_info *grp = ext4_get_group_info(ac->ac_sb, group);
2053 
2054 	BUG_ON(cr < 0 || cr >= 4);
2055 
2056 	free = grp->bb_free;
2057 	if (free == 0)
2058 		return 0;
2059 	if (cr <= 2 && free < ac->ac_g_ex.fe_len)
2060 		return 0;
2061 
2062 	if (unlikely(EXT4_MB_GRP_BBITMAP_CORRUPT(grp)))
2063 		return 0;
2064 
2065 	/* We only do this if the grp has never been initialized */
2066 	if (unlikely(EXT4_MB_GRP_NEED_INIT(grp))) {
2067 		int ret = ext4_mb_init_group(ac->ac_sb, group, GFP_NOFS);
2068 		if (ret)
2069 			return ret;
2070 	}
2071 
2072 	fragments = grp->bb_fragments;
2073 	if (fragments == 0)
2074 		return 0;
2075 
2076 	switch (cr) {
2077 	case 0:
2078 		BUG_ON(ac->ac_2order == 0);
2079 
2080 		/* Avoid using the first bg of a flexgroup for data files */
2081 		if ((ac->ac_flags & EXT4_MB_HINT_DATA) &&
2082 		    (flex_size >= EXT4_FLEX_SIZE_DIR_ALLOC_SCHEME) &&
2083 		    ((group % flex_size) == 0))
2084 			return 0;
2085 
2086 		if ((ac->ac_2order > ac->ac_sb->s_blocksize_bits+1) ||
2087 		    (free / fragments) >= ac->ac_g_ex.fe_len)
2088 			return 1;
2089 
2090 		if (grp->bb_largest_free_order < ac->ac_2order)
2091 			return 0;
2092 
2093 		return 1;
2094 	case 1:
2095 		if ((free / fragments) >= ac->ac_g_ex.fe_len)
2096 			return 1;
2097 		break;
2098 	case 2:
2099 		if (free >= ac->ac_g_ex.fe_len)
2100 			return 1;
2101 		break;
2102 	case 3:
2103 		return 1;
2104 	default:
2105 		BUG();
2106 	}
2107 
2108 	return 0;
2109 }
2110 
2111 static noinline_for_stack int
2112 ext4_mb_regular_allocator(struct ext4_allocation_context *ac)
2113 {
2114 	ext4_group_t ngroups, group, i;
2115 	int cr;
2116 	int err = 0, first_err = 0;
2117 	struct ext4_sb_info *sbi;
2118 	struct super_block *sb;
2119 	struct ext4_buddy e4b;
2120 
2121 	sb = ac->ac_sb;
2122 	sbi = EXT4_SB(sb);
2123 	ngroups = ext4_get_groups_count(sb);
2124 	/* non-extent files are limited to low blocks/groups */
2125 	if (!(ext4_test_inode_flag(ac->ac_inode, EXT4_INODE_EXTENTS)))
2126 		ngroups = sbi->s_blockfile_groups;
2127 
2128 	BUG_ON(ac->ac_status == AC_STATUS_FOUND);
2129 
2130 	/* first, try the goal */
2131 	err = ext4_mb_find_by_goal(ac, &e4b);
2132 	if (err || ac->ac_status == AC_STATUS_FOUND)
2133 		goto out;
2134 
2135 	if (unlikely(ac->ac_flags & EXT4_MB_HINT_GOAL_ONLY))
2136 		goto out;
2137 
2138 	/*
2139 	 * ac->ac2_order is set only if the fe_len is a power of 2
2140 	 * if ac2_order is set we also set criteria to 0 so that we
2141 	 * try exact allocation using buddy.
2142 	 */
2143 	i = fls(ac->ac_g_ex.fe_len);
2144 	ac->ac_2order = 0;
2145 	/*
2146 	 * We search using buddy data only if the order of the request
2147 	 * is greater than equal to the sbi_s_mb_order2_reqs
2148 	 * You can tune it via /sys/fs/ext4/<partition>/mb_order2_req
2149 	 * We also support searching for power-of-two requests only for
2150 	 * requests upto maximum buddy size we have constructed.
2151 	 */
2152 	if (i >= sbi->s_mb_order2_reqs && i <= sb->s_blocksize_bits + 2) {
2153 		/*
2154 		 * This should tell if fe_len is exactly power of 2
2155 		 */
2156 		if ((ac->ac_g_ex.fe_len & (~(1 << (i - 1)))) == 0)
2157 			ac->ac_2order = i - 1;
2158 	}
2159 
2160 	/* if stream allocation is enabled, use global goal */
2161 	if (ac->ac_flags & EXT4_MB_STREAM_ALLOC) {
2162 		/* TBD: may be hot point */
2163 		spin_lock(&sbi->s_md_lock);
2164 		ac->ac_g_ex.fe_group = sbi->s_mb_last_group;
2165 		ac->ac_g_ex.fe_start = sbi->s_mb_last_start;
2166 		spin_unlock(&sbi->s_md_lock);
2167 	}
2168 
2169 	/* Let's just scan groups to find more-less suitable blocks */
2170 	cr = ac->ac_2order ? 0 : 1;
2171 	/*
2172 	 * cr == 0 try to get exact allocation,
2173 	 * cr == 3  try to get anything
2174 	 */
2175 repeat:
2176 	for (; cr < 4 && ac->ac_status == AC_STATUS_CONTINUE; cr++) {
2177 		ac->ac_criteria = cr;
2178 		/*
2179 		 * searching for the right group start
2180 		 * from the goal value specified
2181 		 */
2182 		group = ac->ac_g_ex.fe_group;
2183 
2184 		for (i = 0; i < ngroups; group++, i++) {
2185 			int ret = 0;
2186 			cond_resched();
2187 			/*
2188 			 * Artificially restricted ngroups for non-extent
2189 			 * files makes group > ngroups possible on first loop.
2190 			 */
2191 			if (group >= ngroups)
2192 				group = 0;
2193 
2194 			/* This now checks without needing the buddy page */
2195 			ret = ext4_mb_good_group(ac, group, cr);
2196 			if (ret <= 0) {
2197 				if (!first_err)
2198 					first_err = ret;
2199 				continue;
2200 			}
2201 
2202 			err = ext4_mb_load_buddy(sb, group, &e4b);
2203 			if (err)
2204 				goto out;
2205 
2206 			ext4_lock_group(sb, group);
2207 
2208 			/*
2209 			 * We need to check again after locking the
2210 			 * block group
2211 			 */
2212 			ret = ext4_mb_good_group(ac, group, cr);
2213 			if (ret <= 0) {
2214 				ext4_unlock_group(sb, group);
2215 				ext4_mb_unload_buddy(&e4b);
2216 				if (!first_err)
2217 					first_err = ret;
2218 				continue;
2219 			}
2220 
2221 			ac->ac_groups_scanned++;
2222 			if (cr == 0)
2223 				ext4_mb_simple_scan_group(ac, &e4b);
2224 			else if (cr == 1 && sbi->s_stripe &&
2225 					!(ac->ac_g_ex.fe_len % sbi->s_stripe))
2226 				ext4_mb_scan_aligned(ac, &e4b);
2227 			else
2228 				ext4_mb_complex_scan_group(ac, &e4b);
2229 
2230 			ext4_unlock_group(sb, group);
2231 			ext4_mb_unload_buddy(&e4b);
2232 
2233 			if (ac->ac_status != AC_STATUS_CONTINUE)
2234 				break;
2235 		}
2236 	}
2237 
2238 	if (ac->ac_b_ex.fe_len > 0 && ac->ac_status != AC_STATUS_FOUND &&
2239 	    !(ac->ac_flags & EXT4_MB_HINT_FIRST)) {
2240 		/*
2241 		 * We've been searching too long. Let's try to allocate
2242 		 * the best chunk we've found so far
2243 		 */
2244 
2245 		ext4_mb_try_best_found(ac, &e4b);
2246 		if (ac->ac_status != AC_STATUS_FOUND) {
2247 			/*
2248 			 * Someone more lucky has already allocated it.
2249 			 * The only thing we can do is just take first
2250 			 * found block(s)
2251 			printk(KERN_DEBUG "EXT4-fs: someone won our chunk\n");
2252 			 */
2253 			ac->ac_b_ex.fe_group = 0;
2254 			ac->ac_b_ex.fe_start = 0;
2255 			ac->ac_b_ex.fe_len = 0;
2256 			ac->ac_status = AC_STATUS_CONTINUE;
2257 			ac->ac_flags |= EXT4_MB_HINT_FIRST;
2258 			cr = 3;
2259 			atomic_inc(&sbi->s_mb_lost_chunks);
2260 			goto repeat;
2261 		}
2262 	}
2263 out:
2264 	if (!err && ac->ac_status != AC_STATUS_FOUND && first_err)
2265 		err = first_err;
2266 	return err;
2267 }
2268 
2269 static void *ext4_mb_seq_groups_start(struct seq_file *seq, loff_t *pos)
2270 {
2271 	struct super_block *sb = seq->private;
2272 	ext4_group_t group;
2273 
2274 	if (*pos < 0 || *pos >= ext4_get_groups_count(sb))
2275 		return NULL;
2276 	group = *pos + 1;
2277 	return (void *) ((unsigned long) group);
2278 }
2279 
2280 static void *ext4_mb_seq_groups_next(struct seq_file *seq, void *v, loff_t *pos)
2281 {
2282 	struct super_block *sb = seq->private;
2283 	ext4_group_t group;
2284 
2285 	++*pos;
2286 	if (*pos < 0 || *pos >= ext4_get_groups_count(sb))
2287 		return NULL;
2288 	group = *pos + 1;
2289 	return (void *) ((unsigned long) group);
2290 }
2291 
2292 static int ext4_mb_seq_groups_show(struct seq_file *seq, void *v)
2293 {
2294 	struct super_block *sb = seq->private;
2295 	ext4_group_t group = (ext4_group_t) ((unsigned long) v);
2296 	int i;
2297 	int err, buddy_loaded = 0;
2298 	struct ext4_buddy e4b;
2299 	struct ext4_group_info *grinfo;
2300 	struct sg {
2301 		struct ext4_group_info info;
2302 		ext4_grpblk_t counters[EXT4_MAX_BLOCK_LOG_SIZE + 2];
2303 	} sg;
2304 
2305 	group--;
2306 	if (group == 0)
2307 		seq_puts(seq, "#group: free  frags first ["
2308 			      " 2^0   2^1   2^2   2^3   2^4   2^5   2^6  "
2309 			      " 2^7   2^8   2^9   2^10  2^11  2^12  2^13  ]\n");
2310 
2311 	i = (sb->s_blocksize_bits + 2) * sizeof(sg.info.bb_counters[0]) +
2312 		sizeof(struct ext4_group_info);
2313 	grinfo = ext4_get_group_info(sb, group);
2314 	/* Load the group info in memory only if not already loaded. */
2315 	if (unlikely(EXT4_MB_GRP_NEED_INIT(grinfo))) {
2316 		err = ext4_mb_load_buddy(sb, group, &e4b);
2317 		if (err) {
2318 			seq_printf(seq, "#%-5u: I/O error\n", group);
2319 			return 0;
2320 		}
2321 		buddy_loaded = 1;
2322 	}
2323 
2324 	memcpy(&sg, ext4_get_group_info(sb, group), i);
2325 
2326 	if (buddy_loaded)
2327 		ext4_mb_unload_buddy(&e4b);
2328 
2329 	seq_printf(seq, "#%-5u: %-5u %-5u %-5u [", group, sg.info.bb_free,
2330 			sg.info.bb_fragments, sg.info.bb_first_free);
2331 	for (i = 0; i <= 13; i++)
2332 		seq_printf(seq, " %-5u", i <= sb->s_blocksize_bits + 1 ?
2333 				sg.info.bb_counters[i] : 0);
2334 	seq_printf(seq, " ]\n");
2335 
2336 	return 0;
2337 }
2338 
2339 static void ext4_mb_seq_groups_stop(struct seq_file *seq, void *v)
2340 {
2341 }
2342 
2343 static const struct seq_operations ext4_mb_seq_groups_ops = {
2344 	.start  = ext4_mb_seq_groups_start,
2345 	.next   = ext4_mb_seq_groups_next,
2346 	.stop   = ext4_mb_seq_groups_stop,
2347 	.show   = ext4_mb_seq_groups_show,
2348 };
2349 
2350 static int ext4_mb_seq_groups_open(struct inode *inode, struct file *file)
2351 {
2352 	struct super_block *sb = PDE_DATA(inode);
2353 	int rc;
2354 
2355 	rc = seq_open(file, &ext4_mb_seq_groups_ops);
2356 	if (rc == 0) {
2357 		struct seq_file *m = file->private_data;
2358 		m->private = sb;
2359 	}
2360 	return rc;
2361 
2362 }
2363 
2364 const struct file_operations ext4_seq_mb_groups_fops = {
2365 	.open		= ext4_mb_seq_groups_open,
2366 	.read		= seq_read,
2367 	.llseek		= seq_lseek,
2368 	.release	= seq_release,
2369 };
2370 
2371 static struct kmem_cache *get_groupinfo_cache(int blocksize_bits)
2372 {
2373 	int cache_index = blocksize_bits - EXT4_MIN_BLOCK_LOG_SIZE;
2374 	struct kmem_cache *cachep = ext4_groupinfo_caches[cache_index];
2375 
2376 	BUG_ON(!cachep);
2377 	return cachep;
2378 }
2379 
2380 /*
2381  * Allocate the top-level s_group_info array for the specified number
2382  * of groups
2383  */
2384 int ext4_mb_alloc_groupinfo(struct super_block *sb, ext4_group_t ngroups)
2385 {
2386 	struct ext4_sb_info *sbi = EXT4_SB(sb);
2387 	unsigned size;
2388 	struct ext4_group_info ***new_groupinfo;
2389 
2390 	size = (ngroups + EXT4_DESC_PER_BLOCK(sb) - 1) >>
2391 		EXT4_DESC_PER_BLOCK_BITS(sb);
2392 	if (size <= sbi->s_group_info_size)
2393 		return 0;
2394 
2395 	size = roundup_pow_of_two(sizeof(*sbi->s_group_info) * size);
2396 	new_groupinfo = kvzalloc(size, GFP_KERNEL);
2397 	if (!new_groupinfo) {
2398 		ext4_msg(sb, KERN_ERR, "can't allocate buddy meta group");
2399 		return -ENOMEM;
2400 	}
2401 	if (sbi->s_group_info) {
2402 		memcpy(new_groupinfo, sbi->s_group_info,
2403 		       sbi->s_group_info_size * sizeof(*sbi->s_group_info));
2404 		kvfree(sbi->s_group_info);
2405 	}
2406 	sbi->s_group_info = new_groupinfo;
2407 	sbi->s_group_info_size = size / sizeof(*sbi->s_group_info);
2408 	ext4_debug("allocated s_groupinfo array for %d meta_bg's\n",
2409 		   sbi->s_group_info_size);
2410 	return 0;
2411 }
2412 
2413 /* Create and initialize ext4_group_info data for the given group. */
2414 int ext4_mb_add_groupinfo(struct super_block *sb, ext4_group_t group,
2415 			  struct ext4_group_desc *desc)
2416 {
2417 	int i;
2418 	int metalen = 0;
2419 	struct ext4_sb_info *sbi = EXT4_SB(sb);
2420 	struct ext4_group_info **meta_group_info;
2421 	struct kmem_cache *cachep = get_groupinfo_cache(sb->s_blocksize_bits);
2422 
2423 	/*
2424 	 * First check if this group is the first of a reserved block.
2425 	 * If it's true, we have to allocate a new table of pointers
2426 	 * to ext4_group_info structures
2427 	 */
2428 	if (group % EXT4_DESC_PER_BLOCK(sb) == 0) {
2429 		metalen = sizeof(*meta_group_info) <<
2430 			EXT4_DESC_PER_BLOCK_BITS(sb);
2431 		meta_group_info = kmalloc(metalen, GFP_NOFS);
2432 		if (meta_group_info == NULL) {
2433 			ext4_msg(sb, KERN_ERR, "can't allocate mem "
2434 				 "for a buddy group");
2435 			goto exit_meta_group_info;
2436 		}
2437 		sbi->s_group_info[group >> EXT4_DESC_PER_BLOCK_BITS(sb)] =
2438 			meta_group_info;
2439 	}
2440 
2441 	meta_group_info =
2442 		sbi->s_group_info[group >> EXT4_DESC_PER_BLOCK_BITS(sb)];
2443 	i = group & (EXT4_DESC_PER_BLOCK(sb) - 1);
2444 
2445 	meta_group_info[i] = kmem_cache_zalloc(cachep, GFP_NOFS);
2446 	if (meta_group_info[i] == NULL) {
2447 		ext4_msg(sb, KERN_ERR, "can't allocate buddy mem");
2448 		goto exit_group_info;
2449 	}
2450 	set_bit(EXT4_GROUP_INFO_NEED_INIT_BIT,
2451 		&(meta_group_info[i]->bb_state));
2452 
2453 	/*
2454 	 * initialize bb_free to be able to skip
2455 	 * empty groups without initialization
2456 	 */
2457 	if (desc->bg_flags & cpu_to_le16(EXT4_BG_BLOCK_UNINIT)) {
2458 		meta_group_info[i]->bb_free =
2459 			ext4_free_clusters_after_init(sb, group, desc);
2460 	} else {
2461 		meta_group_info[i]->bb_free =
2462 			ext4_free_group_clusters(sb, desc);
2463 	}
2464 
2465 	INIT_LIST_HEAD(&meta_group_info[i]->bb_prealloc_list);
2466 	init_rwsem(&meta_group_info[i]->alloc_sem);
2467 	meta_group_info[i]->bb_free_root = RB_ROOT;
2468 	meta_group_info[i]->bb_largest_free_order = -1;  /* uninit */
2469 
2470 #ifdef DOUBLE_CHECK
2471 	{
2472 		struct buffer_head *bh;
2473 		meta_group_info[i]->bb_bitmap =
2474 			kmalloc(sb->s_blocksize, GFP_NOFS);
2475 		BUG_ON(meta_group_info[i]->bb_bitmap == NULL);
2476 		bh = ext4_read_block_bitmap(sb, group);
2477 		BUG_ON(IS_ERR_OR_NULL(bh));
2478 		memcpy(meta_group_info[i]->bb_bitmap, bh->b_data,
2479 			sb->s_blocksize);
2480 		put_bh(bh);
2481 	}
2482 #endif
2483 
2484 	return 0;
2485 
2486 exit_group_info:
2487 	/* If a meta_group_info table has been allocated, release it now */
2488 	if (group % EXT4_DESC_PER_BLOCK(sb) == 0) {
2489 		kfree(sbi->s_group_info[group >> EXT4_DESC_PER_BLOCK_BITS(sb)]);
2490 		sbi->s_group_info[group >> EXT4_DESC_PER_BLOCK_BITS(sb)] = NULL;
2491 	}
2492 exit_meta_group_info:
2493 	return -ENOMEM;
2494 } /* ext4_mb_add_groupinfo */
2495 
2496 static int ext4_mb_init_backend(struct super_block *sb)
2497 {
2498 	ext4_group_t ngroups = ext4_get_groups_count(sb);
2499 	ext4_group_t i;
2500 	struct ext4_sb_info *sbi = EXT4_SB(sb);
2501 	int err;
2502 	struct ext4_group_desc *desc;
2503 	struct kmem_cache *cachep;
2504 
2505 	err = ext4_mb_alloc_groupinfo(sb, ngroups);
2506 	if (err)
2507 		return err;
2508 
2509 	sbi->s_buddy_cache = new_inode(sb);
2510 	if (sbi->s_buddy_cache == NULL) {
2511 		ext4_msg(sb, KERN_ERR, "can't get new inode");
2512 		goto err_freesgi;
2513 	}
2514 	/* To avoid potentially colliding with an valid on-disk inode number,
2515 	 * use EXT4_BAD_INO for the buddy cache inode number.  This inode is
2516 	 * not in the inode hash, so it should never be found by iget(), but
2517 	 * this will avoid confusion if it ever shows up during debugging. */
2518 	sbi->s_buddy_cache->i_ino = EXT4_BAD_INO;
2519 	EXT4_I(sbi->s_buddy_cache)->i_disksize = 0;
2520 	for (i = 0; i < ngroups; i++) {
2521 		desc = ext4_get_group_desc(sb, i, NULL);
2522 		if (desc == NULL) {
2523 			ext4_msg(sb, KERN_ERR, "can't read descriptor %u", i);
2524 			goto err_freebuddy;
2525 		}
2526 		if (ext4_mb_add_groupinfo(sb, i, desc) != 0)
2527 			goto err_freebuddy;
2528 	}
2529 
2530 	return 0;
2531 
2532 err_freebuddy:
2533 	cachep = get_groupinfo_cache(sb->s_blocksize_bits);
2534 	while (i-- > 0)
2535 		kmem_cache_free(cachep, ext4_get_group_info(sb, i));
2536 	i = sbi->s_group_info_size;
2537 	while (i-- > 0)
2538 		kfree(sbi->s_group_info[i]);
2539 	iput(sbi->s_buddy_cache);
2540 err_freesgi:
2541 	kvfree(sbi->s_group_info);
2542 	return -ENOMEM;
2543 }
2544 
2545 static void ext4_groupinfo_destroy_slabs(void)
2546 {
2547 	int i;
2548 
2549 	for (i = 0; i < NR_GRPINFO_CACHES; i++) {
2550 		if (ext4_groupinfo_caches[i])
2551 			kmem_cache_destroy(ext4_groupinfo_caches[i]);
2552 		ext4_groupinfo_caches[i] = NULL;
2553 	}
2554 }
2555 
2556 static int ext4_groupinfo_create_slab(size_t size)
2557 {
2558 	static DEFINE_MUTEX(ext4_grpinfo_slab_create_mutex);
2559 	int slab_size;
2560 	int blocksize_bits = order_base_2(size);
2561 	int cache_index = blocksize_bits - EXT4_MIN_BLOCK_LOG_SIZE;
2562 	struct kmem_cache *cachep;
2563 
2564 	if (cache_index >= NR_GRPINFO_CACHES)
2565 		return -EINVAL;
2566 
2567 	if (unlikely(cache_index < 0))
2568 		cache_index = 0;
2569 
2570 	mutex_lock(&ext4_grpinfo_slab_create_mutex);
2571 	if (ext4_groupinfo_caches[cache_index]) {
2572 		mutex_unlock(&ext4_grpinfo_slab_create_mutex);
2573 		return 0;	/* Already created */
2574 	}
2575 
2576 	slab_size = offsetof(struct ext4_group_info,
2577 				bb_counters[blocksize_bits + 2]);
2578 
2579 	cachep = kmem_cache_create(ext4_groupinfo_slab_names[cache_index],
2580 					slab_size, 0, SLAB_RECLAIM_ACCOUNT,
2581 					NULL);
2582 
2583 	ext4_groupinfo_caches[cache_index] = cachep;
2584 
2585 	mutex_unlock(&ext4_grpinfo_slab_create_mutex);
2586 	if (!cachep) {
2587 		printk(KERN_EMERG
2588 		       "EXT4-fs: no memory for groupinfo slab cache\n");
2589 		return -ENOMEM;
2590 	}
2591 
2592 	return 0;
2593 }
2594 
2595 int ext4_mb_init(struct super_block *sb)
2596 {
2597 	struct ext4_sb_info *sbi = EXT4_SB(sb);
2598 	unsigned i, j;
2599 	unsigned offset, offset_incr;
2600 	unsigned max;
2601 	int ret;
2602 
2603 	i = (sb->s_blocksize_bits + 2) * sizeof(*sbi->s_mb_offsets);
2604 
2605 	sbi->s_mb_offsets = kmalloc(i, GFP_KERNEL);
2606 	if (sbi->s_mb_offsets == NULL) {
2607 		ret = -ENOMEM;
2608 		goto out;
2609 	}
2610 
2611 	i = (sb->s_blocksize_bits + 2) * sizeof(*sbi->s_mb_maxs);
2612 	sbi->s_mb_maxs = kmalloc(i, GFP_KERNEL);
2613 	if (sbi->s_mb_maxs == NULL) {
2614 		ret = -ENOMEM;
2615 		goto out;
2616 	}
2617 
2618 	ret = ext4_groupinfo_create_slab(sb->s_blocksize);
2619 	if (ret < 0)
2620 		goto out;
2621 
2622 	/* order 0 is regular bitmap */
2623 	sbi->s_mb_maxs[0] = sb->s_blocksize << 3;
2624 	sbi->s_mb_offsets[0] = 0;
2625 
2626 	i = 1;
2627 	offset = 0;
2628 	offset_incr = 1 << (sb->s_blocksize_bits - 1);
2629 	max = sb->s_blocksize << 2;
2630 	do {
2631 		sbi->s_mb_offsets[i] = offset;
2632 		sbi->s_mb_maxs[i] = max;
2633 		offset += offset_incr;
2634 		offset_incr = offset_incr >> 1;
2635 		max = max >> 1;
2636 		i++;
2637 	} while (i <= sb->s_blocksize_bits + 1);
2638 
2639 	spin_lock_init(&sbi->s_md_lock);
2640 	spin_lock_init(&sbi->s_bal_lock);
2641 	sbi->s_mb_free_pending = 0;
2642 
2643 	sbi->s_mb_max_to_scan = MB_DEFAULT_MAX_TO_SCAN;
2644 	sbi->s_mb_min_to_scan = MB_DEFAULT_MIN_TO_SCAN;
2645 	sbi->s_mb_stats = MB_DEFAULT_STATS;
2646 	sbi->s_mb_stream_request = MB_DEFAULT_STREAM_THRESHOLD;
2647 	sbi->s_mb_order2_reqs = MB_DEFAULT_ORDER2_REQS;
2648 	/*
2649 	 * The default group preallocation is 512, which for 4k block
2650 	 * sizes translates to 2 megabytes.  However for bigalloc file
2651 	 * systems, this is probably too big (i.e, if the cluster size
2652 	 * is 1 megabyte, then group preallocation size becomes half a
2653 	 * gigabyte!).  As a default, we will keep a two megabyte
2654 	 * group pralloc size for cluster sizes up to 64k, and after
2655 	 * that, we will force a minimum group preallocation size of
2656 	 * 32 clusters.  This translates to 8 megs when the cluster
2657 	 * size is 256k, and 32 megs when the cluster size is 1 meg,
2658 	 * which seems reasonable as a default.
2659 	 */
2660 	sbi->s_mb_group_prealloc = max(MB_DEFAULT_GROUP_PREALLOC >>
2661 				       sbi->s_cluster_bits, 32);
2662 	/*
2663 	 * If there is a s_stripe > 1, then we set the s_mb_group_prealloc
2664 	 * to the lowest multiple of s_stripe which is bigger than
2665 	 * the s_mb_group_prealloc as determined above. We want
2666 	 * the preallocation size to be an exact multiple of the
2667 	 * RAID stripe size so that preallocations don't fragment
2668 	 * the stripes.
2669 	 */
2670 	if (sbi->s_stripe > 1) {
2671 		sbi->s_mb_group_prealloc = roundup(
2672 			sbi->s_mb_group_prealloc, sbi->s_stripe);
2673 	}
2674 
2675 	sbi->s_locality_groups = alloc_percpu(struct ext4_locality_group);
2676 	if (sbi->s_locality_groups == NULL) {
2677 		ret = -ENOMEM;
2678 		goto out;
2679 	}
2680 	for_each_possible_cpu(i) {
2681 		struct ext4_locality_group *lg;
2682 		lg = per_cpu_ptr(sbi->s_locality_groups, i);
2683 		mutex_init(&lg->lg_mutex);
2684 		for (j = 0; j < PREALLOC_TB_SIZE; j++)
2685 			INIT_LIST_HEAD(&lg->lg_prealloc_list[j]);
2686 		spin_lock_init(&lg->lg_prealloc_lock);
2687 	}
2688 
2689 	/* init file for buddy data */
2690 	ret = ext4_mb_init_backend(sb);
2691 	if (ret != 0)
2692 		goto out_free_locality_groups;
2693 
2694 	return 0;
2695 
2696 out_free_locality_groups:
2697 	free_percpu(sbi->s_locality_groups);
2698 	sbi->s_locality_groups = NULL;
2699 out:
2700 	kfree(sbi->s_mb_offsets);
2701 	sbi->s_mb_offsets = NULL;
2702 	kfree(sbi->s_mb_maxs);
2703 	sbi->s_mb_maxs = NULL;
2704 	return ret;
2705 }
2706 
2707 /* need to called with the ext4 group lock held */
2708 static void ext4_mb_cleanup_pa(struct ext4_group_info *grp)
2709 {
2710 	struct ext4_prealloc_space *pa;
2711 	struct list_head *cur, *tmp;
2712 	int count = 0;
2713 
2714 	list_for_each_safe(cur, tmp, &grp->bb_prealloc_list) {
2715 		pa = list_entry(cur, struct ext4_prealloc_space, pa_group_list);
2716 		list_del(&pa->pa_group_list);
2717 		count++;
2718 		kmem_cache_free(ext4_pspace_cachep, pa);
2719 	}
2720 	if (count)
2721 		mb_debug(1, "mballoc: %u PAs left\n", count);
2722 
2723 }
2724 
2725 int ext4_mb_release(struct super_block *sb)
2726 {
2727 	ext4_group_t ngroups = ext4_get_groups_count(sb);
2728 	ext4_group_t i;
2729 	int num_meta_group_infos;
2730 	struct ext4_group_info *grinfo;
2731 	struct ext4_sb_info *sbi = EXT4_SB(sb);
2732 	struct kmem_cache *cachep = get_groupinfo_cache(sb->s_blocksize_bits);
2733 
2734 	if (sbi->s_group_info) {
2735 		for (i = 0; i < ngroups; i++) {
2736 			grinfo = ext4_get_group_info(sb, i);
2737 #ifdef DOUBLE_CHECK
2738 			kfree(grinfo->bb_bitmap);
2739 #endif
2740 			ext4_lock_group(sb, i);
2741 			ext4_mb_cleanup_pa(grinfo);
2742 			ext4_unlock_group(sb, i);
2743 			kmem_cache_free(cachep, grinfo);
2744 		}
2745 		num_meta_group_infos = (ngroups +
2746 				EXT4_DESC_PER_BLOCK(sb) - 1) >>
2747 			EXT4_DESC_PER_BLOCK_BITS(sb);
2748 		for (i = 0; i < num_meta_group_infos; i++)
2749 			kfree(sbi->s_group_info[i]);
2750 		kvfree(sbi->s_group_info);
2751 	}
2752 	kfree(sbi->s_mb_offsets);
2753 	kfree(sbi->s_mb_maxs);
2754 	iput(sbi->s_buddy_cache);
2755 	if (sbi->s_mb_stats) {
2756 		ext4_msg(sb, KERN_INFO,
2757 		       "mballoc: %u blocks %u reqs (%u success)",
2758 				atomic_read(&sbi->s_bal_allocated),
2759 				atomic_read(&sbi->s_bal_reqs),
2760 				atomic_read(&sbi->s_bal_success));
2761 		ext4_msg(sb, KERN_INFO,
2762 		      "mballoc: %u extents scanned, %u goal hits, "
2763 				"%u 2^N hits, %u breaks, %u lost",
2764 				atomic_read(&sbi->s_bal_ex_scanned),
2765 				atomic_read(&sbi->s_bal_goals),
2766 				atomic_read(&sbi->s_bal_2orders),
2767 				atomic_read(&sbi->s_bal_breaks),
2768 				atomic_read(&sbi->s_mb_lost_chunks));
2769 		ext4_msg(sb, KERN_INFO,
2770 		       "mballoc: %lu generated and it took %Lu",
2771 				sbi->s_mb_buddies_generated,
2772 				sbi->s_mb_generation_time);
2773 		ext4_msg(sb, KERN_INFO,
2774 		       "mballoc: %u preallocated, %u discarded",
2775 				atomic_read(&sbi->s_mb_preallocated),
2776 				atomic_read(&sbi->s_mb_discarded));
2777 	}
2778 
2779 	free_percpu(sbi->s_locality_groups);
2780 
2781 	return 0;
2782 }
2783 
2784 static inline int ext4_issue_discard(struct super_block *sb,
2785 		ext4_group_t block_group, ext4_grpblk_t cluster, int count)
2786 {
2787 	ext4_fsblk_t discard_block;
2788 
2789 	discard_block = (EXT4_C2B(EXT4_SB(sb), cluster) +
2790 			 ext4_group_first_block_no(sb, block_group));
2791 	count = EXT4_C2B(EXT4_SB(sb), count);
2792 	trace_ext4_discard_blocks(sb,
2793 			(unsigned long long) discard_block, count);
2794 	return sb_issue_discard(sb, discard_block, count, GFP_NOFS, 0);
2795 }
2796 
2797 /*
2798  * This function is called by the jbd2 layer once the commit has finished,
2799  * so we know we can free the blocks that were released with that commit.
2800  */
2801 static void ext4_free_data_callback(struct super_block *sb,
2802 				    struct ext4_journal_cb_entry *jce,
2803 				    int rc)
2804 {
2805 	struct ext4_free_data *entry = (struct ext4_free_data *)jce;
2806 	struct ext4_buddy e4b;
2807 	struct ext4_group_info *db;
2808 	int err, count = 0, count2 = 0;
2809 
2810 	mb_debug(1, "gonna free %u blocks in group %u (0x%p):",
2811 		 entry->efd_count, entry->efd_group, entry);
2812 
2813 	if (test_opt(sb, DISCARD)) {
2814 		err = ext4_issue_discard(sb, entry->efd_group,
2815 					 entry->efd_start_cluster,
2816 					 entry->efd_count);
2817 		if (err && err != -EOPNOTSUPP)
2818 			ext4_msg(sb, KERN_WARNING, "discard request in"
2819 				 " group:%d block:%d count:%d failed"
2820 				 " with %d", entry->efd_group,
2821 				 entry->efd_start_cluster,
2822 				 entry->efd_count, err);
2823 	}
2824 
2825 	err = ext4_mb_load_buddy(sb, entry->efd_group, &e4b);
2826 	/* we expect to find existing buddy because it's pinned */
2827 	BUG_ON(err != 0);
2828 
2829 	spin_lock(&EXT4_SB(sb)->s_md_lock);
2830 	EXT4_SB(sb)->s_mb_free_pending -= entry->efd_count;
2831 	spin_unlock(&EXT4_SB(sb)->s_md_lock);
2832 
2833 	db = e4b.bd_info;
2834 	/* there are blocks to put in buddy to make them really free */
2835 	count += entry->efd_count;
2836 	count2++;
2837 	ext4_lock_group(sb, entry->efd_group);
2838 	/* Take it out of per group rb tree */
2839 	rb_erase(&entry->efd_node, &(db->bb_free_root));
2840 	mb_free_blocks(NULL, &e4b, entry->efd_start_cluster, entry->efd_count);
2841 
2842 	/*
2843 	 * Clear the trimmed flag for the group so that the next
2844 	 * ext4_trim_fs can trim it.
2845 	 * If the volume is mounted with -o discard, online discard
2846 	 * is supported and the free blocks will be trimmed online.
2847 	 */
2848 	if (!test_opt(sb, DISCARD))
2849 		EXT4_MB_GRP_CLEAR_TRIMMED(db);
2850 
2851 	if (!db->bb_free_root.rb_node) {
2852 		/* No more items in the per group rb tree
2853 		 * balance refcounts from ext4_mb_free_metadata()
2854 		 */
2855 		put_page(e4b.bd_buddy_page);
2856 		put_page(e4b.bd_bitmap_page);
2857 	}
2858 	ext4_unlock_group(sb, entry->efd_group);
2859 	kmem_cache_free(ext4_free_data_cachep, entry);
2860 	ext4_mb_unload_buddy(&e4b);
2861 
2862 	mb_debug(1, "freed %u blocks in %u structures\n", count, count2);
2863 }
2864 
2865 int __init ext4_init_mballoc(void)
2866 {
2867 	ext4_pspace_cachep = KMEM_CACHE(ext4_prealloc_space,
2868 					SLAB_RECLAIM_ACCOUNT);
2869 	if (ext4_pspace_cachep == NULL)
2870 		return -ENOMEM;
2871 
2872 	ext4_ac_cachep = KMEM_CACHE(ext4_allocation_context,
2873 				    SLAB_RECLAIM_ACCOUNT);
2874 	if (ext4_ac_cachep == NULL) {
2875 		kmem_cache_destroy(ext4_pspace_cachep);
2876 		return -ENOMEM;
2877 	}
2878 
2879 	ext4_free_data_cachep = KMEM_CACHE(ext4_free_data,
2880 					   SLAB_RECLAIM_ACCOUNT);
2881 	if (ext4_free_data_cachep == NULL) {
2882 		kmem_cache_destroy(ext4_pspace_cachep);
2883 		kmem_cache_destroy(ext4_ac_cachep);
2884 		return -ENOMEM;
2885 	}
2886 	return 0;
2887 }
2888 
2889 void ext4_exit_mballoc(void)
2890 {
2891 	/*
2892 	 * Wait for completion of call_rcu()'s on ext4_pspace_cachep
2893 	 * before destroying the slab cache.
2894 	 */
2895 	rcu_barrier();
2896 	kmem_cache_destroy(ext4_pspace_cachep);
2897 	kmem_cache_destroy(ext4_ac_cachep);
2898 	kmem_cache_destroy(ext4_free_data_cachep);
2899 	ext4_groupinfo_destroy_slabs();
2900 }
2901 
2902 
2903 /*
2904  * Check quota and mark chosen space (ac->ac_b_ex) non-free in bitmaps
2905  * Returns 0 if success or error code
2906  */
2907 static noinline_for_stack int
2908 ext4_mb_mark_diskspace_used(struct ext4_allocation_context *ac,
2909 				handle_t *handle, unsigned int reserv_clstrs)
2910 {
2911 	struct buffer_head *bitmap_bh = NULL;
2912 	struct ext4_group_desc *gdp;
2913 	struct buffer_head *gdp_bh;
2914 	struct ext4_sb_info *sbi;
2915 	struct super_block *sb;
2916 	ext4_fsblk_t block;
2917 	int err, len;
2918 
2919 	BUG_ON(ac->ac_status != AC_STATUS_FOUND);
2920 	BUG_ON(ac->ac_b_ex.fe_len <= 0);
2921 
2922 	sb = ac->ac_sb;
2923 	sbi = EXT4_SB(sb);
2924 
2925 	bitmap_bh = ext4_read_block_bitmap(sb, ac->ac_b_ex.fe_group);
2926 	if (IS_ERR(bitmap_bh)) {
2927 		err = PTR_ERR(bitmap_bh);
2928 		bitmap_bh = NULL;
2929 		goto out_err;
2930 	}
2931 
2932 	BUFFER_TRACE(bitmap_bh, "getting write access");
2933 	err = ext4_journal_get_write_access(handle, bitmap_bh);
2934 	if (err)
2935 		goto out_err;
2936 
2937 	err = -EIO;
2938 	gdp = ext4_get_group_desc(sb, ac->ac_b_ex.fe_group, &gdp_bh);
2939 	if (!gdp)
2940 		goto out_err;
2941 
2942 	ext4_debug("using block group %u(%d)\n", ac->ac_b_ex.fe_group,
2943 			ext4_free_group_clusters(sb, gdp));
2944 
2945 	BUFFER_TRACE(gdp_bh, "get_write_access");
2946 	err = ext4_journal_get_write_access(handle, gdp_bh);
2947 	if (err)
2948 		goto out_err;
2949 
2950 	block = ext4_grp_offs_to_block(sb, &ac->ac_b_ex);
2951 
2952 	len = EXT4_C2B(sbi, ac->ac_b_ex.fe_len);
2953 	if (!ext4_data_block_valid(sbi, block, len)) {
2954 		ext4_error(sb, "Allocating blocks %llu-%llu which overlap "
2955 			   "fs metadata", block, block+len);
2956 		/* File system mounted not to panic on error
2957 		 * Fix the bitmap and return EFSCORRUPTED
2958 		 * We leak some of the blocks here.
2959 		 */
2960 		ext4_lock_group(sb, ac->ac_b_ex.fe_group);
2961 		ext4_set_bits(bitmap_bh->b_data, ac->ac_b_ex.fe_start,
2962 			      ac->ac_b_ex.fe_len);
2963 		ext4_unlock_group(sb, ac->ac_b_ex.fe_group);
2964 		err = ext4_handle_dirty_metadata(handle, NULL, bitmap_bh);
2965 		if (!err)
2966 			err = -EFSCORRUPTED;
2967 		goto out_err;
2968 	}
2969 
2970 	ext4_lock_group(sb, ac->ac_b_ex.fe_group);
2971 #ifdef AGGRESSIVE_CHECK
2972 	{
2973 		int i;
2974 		for (i = 0; i < ac->ac_b_ex.fe_len; i++) {
2975 			BUG_ON(mb_test_bit(ac->ac_b_ex.fe_start + i,
2976 						bitmap_bh->b_data));
2977 		}
2978 	}
2979 #endif
2980 	ext4_set_bits(bitmap_bh->b_data, ac->ac_b_ex.fe_start,
2981 		      ac->ac_b_ex.fe_len);
2982 	if (gdp->bg_flags & cpu_to_le16(EXT4_BG_BLOCK_UNINIT)) {
2983 		gdp->bg_flags &= cpu_to_le16(~EXT4_BG_BLOCK_UNINIT);
2984 		ext4_free_group_clusters_set(sb, gdp,
2985 					     ext4_free_clusters_after_init(sb,
2986 						ac->ac_b_ex.fe_group, gdp));
2987 	}
2988 	len = ext4_free_group_clusters(sb, gdp) - ac->ac_b_ex.fe_len;
2989 	ext4_free_group_clusters_set(sb, gdp, len);
2990 	ext4_block_bitmap_csum_set(sb, ac->ac_b_ex.fe_group, gdp, bitmap_bh);
2991 	ext4_group_desc_csum_set(sb, ac->ac_b_ex.fe_group, gdp);
2992 
2993 	ext4_unlock_group(sb, ac->ac_b_ex.fe_group);
2994 	percpu_counter_sub(&sbi->s_freeclusters_counter, ac->ac_b_ex.fe_len);
2995 	/*
2996 	 * Now reduce the dirty block count also. Should not go negative
2997 	 */
2998 	if (!(ac->ac_flags & EXT4_MB_DELALLOC_RESERVED))
2999 		/* release all the reserved blocks if non delalloc */
3000 		percpu_counter_sub(&sbi->s_dirtyclusters_counter,
3001 				   reserv_clstrs);
3002 
3003 	if (sbi->s_log_groups_per_flex) {
3004 		ext4_group_t flex_group = ext4_flex_group(sbi,
3005 							  ac->ac_b_ex.fe_group);
3006 		atomic64_sub(ac->ac_b_ex.fe_len,
3007 			     &sbi->s_flex_groups[flex_group].free_clusters);
3008 	}
3009 
3010 	err = ext4_handle_dirty_metadata(handle, NULL, bitmap_bh);
3011 	if (err)
3012 		goto out_err;
3013 	err = ext4_handle_dirty_metadata(handle, NULL, gdp_bh);
3014 
3015 out_err:
3016 	brelse(bitmap_bh);
3017 	return err;
3018 }
3019 
3020 /*
3021  * here we normalize request for locality group
3022  * Group request are normalized to s_mb_group_prealloc, which goes to
3023  * s_strip if we set the same via mount option.
3024  * s_mb_group_prealloc can be configured via
3025  * /sys/fs/ext4/<partition>/mb_group_prealloc
3026  *
3027  * XXX: should we try to preallocate more than the group has now?
3028  */
3029 static void ext4_mb_normalize_group_request(struct ext4_allocation_context *ac)
3030 {
3031 	struct super_block *sb = ac->ac_sb;
3032 	struct ext4_locality_group *lg = ac->ac_lg;
3033 
3034 	BUG_ON(lg == NULL);
3035 	ac->ac_g_ex.fe_len = EXT4_SB(sb)->s_mb_group_prealloc;
3036 	mb_debug(1, "#%u: goal %u blocks for locality group\n",
3037 		current->pid, ac->ac_g_ex.fe_len);
3038 }
3039 
3040 /*
3041  * Normalization means making request better in terms of
3042  * size and alignment
3043  */
3044 static noinline_for_stack void
3045 ext4_mb_normalize_request(struct ext4_allocation_context *ac,
3046 				struct ext4_allocation_request *ar)
3047 {
3048 	struct ext4_sb_info *sbi = EXT4_SB(ac->ac_sb);
3049 	int bsbits, max;
3050 	ext4_lblk_t end;
3051 	loff_t size, start_off;
3052 	loff_t orig_size __maybe_unused;
3053 	ext4_lblk_t start;
3054 	struct ext4_inode_info *ei = EXT4_I(ac->ac_inode);
3055 	struct ext4_prealloc_space *pa;
3056 
3057 	/* do normalize only data requests, metadata requests
3058 	   do not need preallocation */
3059 	if (!(ac->ac_flags & EXT4_MB_HINT_DATA))
3060 		return;
3061 
3062 	/* sometime caller may want exact blocks */
3063 	if (unlikely(ac->ac_flags & EXT4_MB_HINT_GOAL_ONLY))
3064 		return;
3065 
3066 	/* caller may indicate that preallocation isn't
3067 	 * required (it's a tail, for example) */
3068 	if (ac->ac_flags & EXT4_MB_HINT_NOPREALLOC)
3069 		return;
3070 
3071 	if (ac->ac_flags & EXT4_MB_HINT_GROUP_ALLOC) {
3072 		ext4_mb_normalize_group_request(ac);
3073 		return ;
3074 	}
3075 
3076 	bsbits = ac->ac_sb->s_blocksize_bits;
3077 
3078 	/* first, let's learn actual file size
3079 	 * given current request is allocated */
3080 	size = ac->ac_o_ex.fe_logical + EXT4_C2B(sbi, ac->ac_o_ex.fe_len);
3081 	size = size << bsbits;
3082 	if (size < i_size_read(ac->ac_inode))
3083 		size = i_size_read(ac->ac_inode);
3084 	orig_size = size;
3085 
3086 	/* max size of free chunks */
3087 	max = 2 << bsbits;
3088 
3089 #define NRL_CHECK_SIZE(req, size, max, chunk_size)	\
3090 		(req <= (size) || max <= (chunk_size))
3091 
3092 	/* first, try to predict filesize */
3093 	/* XXX: should this table be tunable? */
3094 	start_off = 0;
3095 	if (size <= 16 * 1024) {
3096 		size = 16 * 1024;
3097 	} else if (size <= 32 * 1024) {
3098 		size = 32 * 1024;
3099 	} else if (size <= 64 * 1024) {
3100 		size = 64 * 1024;
3101 	} else if (size <= 128 * 1024) {
3102 		size = 128 * 1024;
3103 	} else if (size <= 256 * 1024) {
3104 		size = 256 * 1024;
3105 	} else if (size <= 512 * 1024) {
3106 		size = 512 * 1024;
3107 	} else if (size <= 1024 * 1024) {
3108 		size = 1024 * 1024;
3109 	} else if (NRL_CHECK_SIZE(size, 4 * 1024 * 1024, max, 2 * 1024)) {
3110 		start_off = ((loff_t)ac->ac_o_ex.fe_logical >>
3111 						(21 - bsbits)) << 21;
3112 		size = 2 * 1024 * 1024;
3113 	} else if (NRL_CHECK_SIZE(size, 8 * 1024 * 1024, max, 4 * 1024)) {
3114 		start_off = ((loff_t)ac->ac_o_ex.fe_logical >>
3115 							(22 - bsbits)) << 22;
3116 		size = 4 * 1024 * 1024;
3117 	} else if (NRL_CHECK_SIZE(ac->ac_o_ex.fe_len,
3118 					(8<<20)>>bsbits, max, 8 * 1024)) {
3119 		start_off = ((loff_t)ac->ac_o_ex.fe_logical >>
3120 							(23 - bsbits)) << 23;
3121 		size = 8 * 1024 * 1024;
3122 	} else {
3123 		start_off = (loff_t) ac->ac_o_ex.fe_logical << bsbits;
3124 		size	  = (loff_t) EXT4_C2B(EXT4_SB(ac->ac_sb),
3125 					      ac->ac_o_ex.fe_len) << bsbits;
3126 	}
3127 	size = size >> bsbits;
3128 	start = start_off >> bsbits;
3129 
3130 	/* don't cover already allocated blocks in selected range */
3131 	if (ar->pleft && start <= ar->lleft) {
3132 		size -= ar->lleft + 1 - start;
3133 		start = ar->lleft + 1;
3134 	}
3135 	if (ar->pright && start + size - 1 >= ar->lright)
3136 		size -= start + size - ar->lright;
3137 
3138 	/*
3139 	 * Trim allocation request for filesystems with artificially small
3140 	 * groups.
3141 	 */
3142 	if (size > EXT4_BLOCKS_PER_GROUP(ac->ac_sb))
3143 		size = EXT4_BLOCKS_PER_GROUP(ac->ac_sb);
3144 
3145 	end = start + size;
3146 
3147 	/* check we don't cross already preallocated blocks */
3148 	rcu_read_lock();
3149 	list_for_each_entry_rcu(pa, &ei->i_prealloc_list, pa_inode_list) {
3150 		ext4_lblk_t pa_end;
3151 
3152 		if (pa->pa_deleted)
3153 			continue;
3154 		spin_lock(&pa->pa_lock);
3155 		if (pa->pa_deleted) {
3156 			spin_unlock(&pa->pa_lock);
3157 			continue;
3158 		}
3159 
3160 		pa_end = pa->pa_lstart + EXT4_C2B(EXT4_SB(ac->ac_sb),
3161 						  pa->pa_len);
3162 
3163 		/* PA must not overlap original request */
3164 		BUG_ON(!(ac->ac_o_ex.fe_logical >= pa_end ||
3165 			ac->ac_o_ex.fe_logical < pa->pa_lstart));
3166 
3167 		/* skip PAs this normalized request doesn't overlap with */
3168 		if (pa->pa_lstart >= end || pa_end <= start) {
3169 			spin_unlock(&pa->pa_lock);
3170 			continue;
3171 		}
3172 		BUG_ON(pa->pa_lstart <= start && pa_end >= end);
3173 
3174 		/* adjust start or end to be adjacent to this pa */
3175 		if (pa_end <= ac->ac_o_ex.fe_logical) {
3176 			BUG_ON(pa_end < start);
3177 			start = pa_end;
3178 		} else if (pa->pa_lstart > ac->ac_o_ex.fe_logical) {
3179 			BUG_ON(pa->pa_lstart > end);
3180 			end = pa->pa_lstart;
3181 		}
3182 		spin_unlock(&pa->pa_lock);
3183 	}
3184 	rcu_read_unlock();
3185 	size = end - start;
3186 
3187 	/* XXX: extra loop to check we really don't overlap preallocations */
3188 	rcu_read_lock();
3189 	list_for_each_entry_rcu(pa, &ei->i_prealloc_list, pa_inode_list) {
3190 		ext4_lblk_t pa_end;
3191 
3192 		spin_lock(&pa->pa_lock);
3193 		if (pa->pa_deleted == 0) {
3194 			pa_end = pa->pa_lstart + EXT4_C2B(EXT4_SB(ac->ac_sb),
3195 							  pa->pa_len);
3196 			BUG_ON(!(start >= pa_end || end <= pa->pa_lstart));
3197 		}
3198 		spin_unlock(&pa->pa_lock);
3199 	}
3200 	rcu_read_unlock();
3201 
3202 	if (start + size <= ac->ac_o_ex.fe_logical &&
3203 			start > ac->ac_o_ex.fe_logical) {
3204 		ext4_msg(ac->ac_sb, KERN_ERR,
3205 			 "start %lu, size %lu, fe_logical %lu",
3206 			 (unsigned long) start, (unsigned long) size,
3207 			 (unsigned long) ac->ac_o_ex.fe_logical);
3208 		BUG();
3209 	}
3210 	BUG_ON(size <= 0 || size > EXT4_BLOCKS_PER_GROUP(ac->ac_sb));
3211 
3212 	/* now prepare goal request */
3213 
3214 	/* XXX: is it better to align blocks WRT to logical
3215 	 * placement or satisfy big request as is */
3216 	ac->ac_g_ex.fe_logical = start;
3217 	ac->ac_g_ex.fe_len = EXT4_NUM_B2C(sbi, size);
3218 
3219 	/* define goal start in order to merge */
3220 	if (ar->pright && (ar->lright == (start + size))) {
3221 		/* merge to the right */
3222 		ext4_get_group_no_and_offset(ac->ac_sb, ar->pright - size,
3223 						&ac->ac_f_ex.fe_group,
3224 						&ac->ac_f_ex.fe_start);
3225 		ac->ac_flags |= EXT4_MB_HINT_TRY_GOAL;
3226 	}
3227 	if (ar->pleft && (ar->lleft + 1 == start)) {
3228 		/* merge to the left */
3229 		ext4_get_group_no_and_offset(ac->ac_sb, ar->pleft + 1,
3230 						&ac->ac_f_ex.fe_group,
3231 						&ac->ac_f_ex.fe_start);
3232 		ac->ac_flags |= EXT4_MB_HINT_TRY_GOAL;
3233 	}
3234 
3235 	mb_debug(1, "goal: %u(was %u) blocks at %u\n", (unsigned) size,
3236 		(unsigned) orig_size, (unsigned) start);
3237 }
3238 
3239 static void ext4_mb_collect_stats(struct ext4_allocation_context *ac)
3240 {
3241 	struct ext4_sb_info *sbi = EXT4_SB(ac->ac_sb);
3242 
3243 	if (sbi->s_mb_stats && ac->ac_g_ex.fe_len > 1) {
3244 		atomic_inc(&sbi->s_bal_reqs);
3245 		atomic_add(ac->ac_b_ex.fe_len, &sbi->s_bal_allocated);
3246 		if (ac->ac_b_ex.fe_len >= ac->ac_o_ex.fe_len)
3247 			atomic_inc(&sbi->s_bal_success);
3248 		atomic_add(ac->ac_found, &sbi->s_bal_ex_scanned);
3249 		if (ac->ac_g_ex.fe_start == ac->ac_b_ex.fe_start &&
3250 				ac->ac_g_ex.fe_group == ac->ac_b_ex.fe_group)
3251 			atomic_inc(&sbi->s_bal_goals);
3252 		if (ac->ac_found > sbi->s_mb_max_to_scan)
3253 			atomic_inc(&sbi->s_bal_breaks);
3254 	}
3255 
3256 	if (ac->ac_op == EXT4_MB_HISTORY_ALLOC)
3257 		trace_ext4_mballoc_alloc(ac);
3258 	else
3259 		trace_ext4_mballoc_prealloc(ac);
3260 }
3261 
3262 /*
3263  * Called on failure; free up any blocks from the inode PA for this
3264  * context.  We don't need this for MB_GROUP_PA because we only change
3265  * pa_free in ext4_mb_release_context(), but on failure, we've already
3266  * zeroed out ac->ac_b_ex.fe_len, so group_pa->pa_free is not changed.
3267  */
3268 static void ext4_discard_allocated_blocks(struct ext4_allocation_context *ac)
3269 {
3270 	struct ext4_prealloc_space *pa = ac->ac_pa;
3271 	struct ext4_buddy e4b;
3272 	int err;
3273 
3274 	if (pa == NULL) {
3275 		if (ac->ac_f_ex.fe_len == 0)
3276 			return;
3277 		err = ext4_mb_load_buddy(ac->ac_sb, ac->ac_f_ex.fe_group, &e4b);
3278 		if (err) {
3279 			/*
3280 			 * This should never happen since we pin the
3281 			 * pages in the ext4_allocation_context so
3282 			 * ext4_mb_load_buddy() should never fail.
3283 			 */
3284 			WARN(1, "mb_load_buddy failed (%d)", err);
3285 			return;
3286 		}
3287 		ext4_lock_group(ac->ac_sb, ac->ac_f_ex.fe_group);
3288 		mb_free_blocks(ac->ac_inode, &e4b, ac->ac_f_ex.fe_start,
3289 			       ac->ac_f_ex.fe_len);
3290 		ext4_unlock_group(ac->ac_sb, ac->ac_f_ex.fe_group);
3291 		ext4_mb_unload_buddy(&e4b);
3292 		return;
3293 	}
3294 	if (pa->pa_type == MB_INODE_PA)
3295 		pa->pa_free += ac->ac_b_ex.fe_len;
3296 }
3297 
3298 /*
3299  * use blocks preallocated to inode
3300  */
3301 static void ext4_mb_use_inode_pa(struct ext4_allocation_context *ac,
3302 				struct ext4_prealloc_space *pa)
3303 {
3304 	struct ext4_sb_info *sbi = EXT4_SB(ac->ac_sb);
3305 	ext4_fsblk_t start;
3306 	ext4_fsblk_t end;
3307 	int len;
3308 
3309 	/* found preallocated blocks, use them */
3310 	start = pa->pa_pstart + (ac->ac_o_ex.fe_logical - pa->pa_lstart);
3311 	end = min(pa->pa_pstart + EXT4_C2B(sbi, pa->pa_len),
3312 		  start + EXT4_C2B(sbi, ac->ac_o_ex.fe_len));
3313 	len = EXT4_NUM_B2C(sbi, end - start);
3314 	ext4_get_group_no_and_offset(ac->ac_sb, start, &ac->ac_b_ex.fe_group,
3315 					&ac->ac_b_ex.fe_start);
3316 	ac->ac_b_ex.fe_len = len;
3317 	ac->ac_status = AC_STATUS_FOUND;
3318 	ac->ac_pa = pa;
3319 
3320 	BUG_ON(start < pa->pa_pstart);
3321 	BUG_ON(end > pa->pa_pstart + EXT4_C2B(sbi, pa->pa_len));
3322 	BUG_ON(pa->pa_free < len);
3323 	pa->pa_free -= len;
3324 
3325 	mb_debug(1, "use %llu/%u from inode pa %p\n", start, len, pa);
3326 }
3327 
3328 /*
3329  * use blocks preallocated to locality group
3330  */
3331 static void ext4_mb_use_group_pa(struct ext4_allocation_context *ac,
3332 				struct ext4_prealloc_space *pa)
3333 {
3334 	unsigned int len = ac->ac_o_ex.fe_len;
3335 
3336 	ext4_get_group_no_and_offset(ac->ac_sb, pa->pa_pstart,
3337 					&ac->ac_b_ex.fe_group,
3338 					&ac->ac_b_ex.fe_start);
3339 	ac->ac_b_ex.fe_len = len;
3340 	ac->ac_status = AC_STATUS_FOUND;
3341 	ac->ac_pa = pa;
3342 
3343 	/* we don't correct pa_pstart or pa_plen here to avoid
3344 	 * possible race when the group is being loaded concurrently
3345 	 * instead we correct pa later, after blocks are marked
3346 	 * in on-disk bitmap -- see ext4_mb_release_context()
3347 	 * Other CPUs are prevented from allocating from this pa by lg_mutex
3348 	 */
3349 	mb_debug(1, "use %u/%u from group pa %p\n", pa->pa_lstart-len, len, pa);
3350 }
3351 
3352 /*
3353  * Return the prealloc space that have minimal distance
3354  * from the goal block. @cpa is the prealloc
3355  * space that is having currently known minimal distance
3356  * from the goal block.
3357  */
3358 static struct ext4_prealloc_space *
3359 ext4_mb_check_group_pa(ext4_fsblk_t goal_block,
3360 			struct ext4_prealloc_space *pa,
3361 			struct ext4_prealloc_space *cpa)
3362 {
3363 	ext4_fsblk_t cur_distance, new_distance;
3364 
3365 	if (cpa == NULL) {
3366 		atomic_inc(&pa->pa_count);
3367 		return pa;
3368 	}
3369 	cur_distance = abs(goal_block - cpa->pa_pstart);
3370 	new_distance = abs(goal_block - pa->pa_pstart);
3371 
3372 	if (cur_distance <= new_distance)
3373 		return cpa;
3374 
3375 	/* drop the previous reference */
3376 	atomic_dec(&cpa->pa_count);
3377 	atomic_inc(&pa->pa_count);
3378 	return pa;
3379 }
3380 
3381 /*
3382  * search goal blocks in preallocated space
3383  */
3384 static noinline_for_stack int
3385 ext4_mb_use_preallocated(struct ext4_allocation_context *ac)
3386 {
3387 	struct ext4_sb_info *sbi = EXT4_SB(ac->ac_sb);
3388 	int order, i;
3389 	struct ext4_inode_info *ei = EXT4_I(ac->ac_inode);
3390 	struct ext4_locality_group *lg;
3391 	struct ext4_prealloc_space *pa, *cpa = NULL;
3392 	ext4_fsblk_t goal_block;
3393 
3394 	/* only data can be preallocated */
3395 	if (!(ac->ac_flags & EXT4_MB_HINT_DATA))
3396 		return 0;
3397 
3398 	/* first, try per-file preallocation */
3399 	rcu_read_lock();
3400 	list_for_each_entry_rcu(pa, &ei->i_prealloc_list, pa_inode_list) {
3401 
3402 		/* all fields in this condition don't change,
3403 		 * so we can skip locking for them */
3404 		if (ac->ac_o_ex.fe_logical < pa->pa_lstart ||
3405 		    ac->ac_o_ex.fe_logical >= (pa->pa_lstart +
3406 					       EXT4_C2B(sbi, pa->pa_len)))
3407 			continue;
3408 
3409 		/* non-extent files can't have physical blocks past 2^32 */
3410 		if (!(ext4_test_inode_flag(ac->ac_inode, EXT4_INODE_EXTENTS)) &&
3411 		    (pa->pa_pstart + EXT4_C2B(sbi, pa->pa_len) >
3412 		     EXT4_MAX_BLOCK_FILE_PHYS))
3413 			continue;
3414 
3415 		/* found preallocated blocks, use them */
3416 		spin_lock(&pa->pa_lock);
3417 		if (pa->pa_deleted == 0 && pa->pa_free) {
3418 			atomic_inc(&pa->pa_count);
3419 			ext4_mb_use_inode_pa(ac, pa);
3420 			spin_unlock(&pa->pa_lock);
3421 			ac->ac_criteria = 10;
3422 			rcu_read_unlock();
3423 			return 1;
3424 		}
3425 		spin_unlock(&pa->pa_lock);
3426 	}
3427 	rcu_read_unlock();
3428 
3429 	/* can we use group allocation? */
3430 	if (!(ac->ac_flags & EXT4_MB_HINT_GROUP_ALLOC))
3431 		return 0;
3432 
3433 	/* inode may have no locality group for some reason */
3434 	lg = ac->ac_lg;
3435 	if (lg == NULL)
3436 		return 0;
3437 	order  = fls(ac->ac_o_ex.fe_len) - 1;
3438 	if (order > PREALLOC_TB_SIZE - 1)
3439 		/* The max size of hash table is PREALLOC_TB_SIZE */
3440 		order = PREALLOC_TB_SIZE - 1;
3441 
3442 	goal_block = ext4_grp_offs_to_block(ac->ac_sb, &ac->ac_g_ex);
3443 	/*
3444 	 * search for the prealloc space that is having
3445 	 * minimal distance from the goal block.
3446 	 */
3447 	for (i = order; i < PREALLOC_TB_SIZE; i++) {
3448 		rcu_read_lock();
3449 		list_for_each_entry_rcu(pa, &lg->lg_prealloc_list[i],
3450 					pa_inode_list) {
3451 			spin_lock(&pa->pa_lock);
3452 			if (pa->pa_deleted == 0 &&
3453 					pa->pa_free >= ac->ac_o_ex.fe_len) {
3454 
3455 				cpa = ext4_mb_check_group_pa(goal_block,
3456 								pa, cpa);
3457 			}
3458 			spin_unlock(&pa->pa_lock);
3459 		}
3460 		rcu_read_unlock();
3461 	}
3462 	if (cpa) {
3463 		ext4_mb_use_group_pa(ac, cpa);
3464 		ac->ac_criteria = 20;
3465 		return 1;
3466 	}
3467 	return 0;
3468 }
3469 
3470 /*
3471  * the function goes through all block freed in the group
3472  * but not yet committed and marks them used in in-core bitmap.
3473  * buddy must be generated from this bitmap
3474  * Need to be called with the ext4 group lock held
3475  */
3476 static void ext4_mb_generate_from_freelist(struct super_block *sb, void *bitmap,
3477 						ext4_group_t group)
3478 {
3479 	struct rb_node *n;
3480 	struct ext4_group_info *grp;
3481 	struct ext4_free_data *entry;
3482 
3483 	grp = ext4_get_group_info(sb, group);
3484 	n = rb_first(&(grp->bb_free_root));
3485 
3486 	while (n) {
3487 		entry = rb_entry(n, struct ext4_free_data, efd_node);
3488 		ext4_set_bits(bitmap, entry->efd_start_cluster, entry->efd_count);
3489 		n = rb_next(n);
3490 	}
3491 	return;
3492 }
3493 
3494 /*
3495  * the function goes through all preallocation in this group and marks them
3496  * used in in-core bitmap. buddy must be generated from this bitmap
3497  * Need to be called with ext4 group lock held
3498  */
3499 static noinline_for_stack
3500 void ext4_mb_generate_from_pa(struct super_block *sb, void *bitmap,
3501 					ext4_group_t group)
3502 {
3503 	struct ext4_group_info *grp = ext4_get_group_info(sb, group);
3504 	struct ext4_prealloc_space *pa;
3505 	struct list_head *cur;
3506 	ext4_group_t groupnr;
3507 	ext4_grpblk_t start;
3508 	int preallocated = 0;
3509 	int len;
3510 
3511 	/* all form of preallocation discards first load group,
3512 	 * so the only competing code is preallocation use.
3513 	 * we don't need any locking here
3514 	 * notice we do NOT ignore preallocations with pa_deleted
3515 	 * otherwise we could leave used blocks available for
3516 	 * allocation in buddy when concurrent ext4_mb_put_pa()
3517 	 * is dropping preallocation
3518 	 */
3519 	list_for_each(cur, &grp->bb_prealloc_list) {
3520 		pa = list_entry(cur, struct ext4_prealloc_space, pa_group_list);
3521 		spin_lock(&pa->pa_lock);
3522 		ext4_get_group_no_and_offset(sb, pa->pa_pstart,
3523 					     &groupnr, &start);
3524 		len = pa->pa_len;
3525 		spin_unlock(&pa->pa_lock);
3526 		if (unlikely(len == 0))
3527 			continue;
3528 		BUG_ON(groupnr != group);
3529 		ext4_set_bits(bitmap, start, len);
3530 		preallocated += len;
3531 	}
3532 	mb_debug(1, "prellocated %u for group %u\n", preallocated, group);
3533 }
3534 
3535 static void ext4_mb_pa_callback(struct rcu_head *head)
3536 {
3537 	struct ext4_prealloc_space *pa;
3538 	pa = container_of(head, struct ext4_prealloc_space, u.pa_rcu);
3539 
3540 	BUG_ON(atomic_read(&pa->pa_count));
3541 	BUG_ON(pa->pa_deleted == 0);
3542 	kmem_cache_free(ext4_pspace_cachep, pa);
3543 }
3544 
3545 /*
3546  * drops a reference to preallocated space descriptor
3547  * if this was the last reference and the space is consumed
3548  */
3549 static void ext4_mb_put_pa(struct ext4_allocation_context *ac,
3550 			struct super_block *sb, struct ext4_prealloc_space *pa)
3551 {
3552 	ext4_group_t grp;
3553 	ext4_fsblk_t grp_blk;
3554 
3555 	/* in this short window concurrent discard can set pa_deleted */
3556 	spin_lock(&pa->pa_lock);
3557 	if (!atomic_dec_and_test(&pa->pa_count) || pa->pa_free != 0) {
3558 		spin_unlock(&pa->pa_lock);
3559 		return;
3560 	}
3561 
3562 	if (pa->pa_deleted == 1) {
3563 		spin_unlock(&pa->pa_lock);
3564 		return;
3565 	}
3566 
3567 	pa->pa_deleted = 1;
3568 	spin_unlock(&pa->pa_lock);
3569 
3570 	grp_blk = pa->pa_pstart;
3571 	/*
3572 	 * If doing group-based preallocation, pa_pstart may be in the
3573 	 * next group when pa is used up
3574 	 */
3575 	if (pa->pa_type == MB_GROUP_PA)
3576 		grp_blk--;
3577 
3578 	grp = ext4_get_group_number(sb, grp_blk);
3579 
3580 	/*
3581 	 * possible race:
3582 	 *
3583 	 *  P1 (buddy init)			P2 (regular allocation)
3584 	 *					find block B in PA
3585 	 *  copy on-disk bitmap to buddy
3586 	 *  					mark B in on-disk bitmap
3587 	 *					drop PA from group
3588 	 *  mark all PAs in buddy
3589 	 *
3590 	 * thus, P1 initializes buddy with B available. to prevent this
3591 	 * we make "copy" and "mark all PAs" atomic and serialize "drop PA"
3592 	 * against that pair
3593 	 */
3594 	ext4_lock_group(sb, grp);
3595 	list_del(&pa->pa_group_list);
3596 	ext4_unlock_group(sb, grp);
3597 
3598 	spin_lock(pa->pa_obj_lock);
3599 	list_del_rcu(&pa->pa_inode_list);
3600 	spin_unlock(pa->pa_obj_lock);
3601 
3602 	call_rcu(&(pa)->u.pa_rcu, ext4_mb_pa_callback);
3603 }
3604 
3605 /*
3606  * creates new preallocated space for given inode
3607  */
3608 static noinline_for_stack int
3609 ext4_mb_new_inode_pa(struct ext4_allocation_context *ac)
3610 {
3611 	struct super_block *sb = ac->ac_sb;
3612 	struct ext4_sb_info *sbi = EXT4_SB(sb);
3613 	struct ext4_prealloc_space *pa;
3614 	struct ext4_group_info *grp;
3615 	struct ext4_inode_info *ei;
3616 
3617 	/* preallocate only when found space is larger then requested */
3618 	BUG_ON(ac->ac_o_ex.fe_len >= ac->ac_b_ex.fe_len);
3619 	BUG_ON(ac->ac_status != AC_STATUS_FOUND);
3620 	BUG_ON(!S_ISREG(ac->ac_inode->i_mode));
3621 
3622 	pa = kmem_cache_alloc(ext4_pspace_cachep, GFP_NOFS);
3623 	if (pa == NULL)
3624 		return -ENOMEM;
3625 
3626 	if (ac->ac_b_ex.fe_len < ac->ac_g_ex.fe_len) {
3627 		int winl;
3628 		int wins;
3629 		int win;
3630 		int offs;
3631 
3632 		/* we can't allocate as much as normalizer wants.
3633 		 * so, found space must get proper lstart
3634 		 * to cover original request */
3635 		BUG_ON(ac->ac_g_ex.fe_logical > ac->ac_o_ex.fe_logical);
3636 		BUG_ON(ac->ac_g_ex.fe_len < ac->ac_o_ex.fe_len);
3637 
3638 		/* we're limited by original request in that
3639 		 * logical block must be covered any way
3640 		 * winl is window we can move our chunk within */
3641 		winl = ac->ac_o_ex.fe_logical - ac->ac_g_ex.fe_logical;
3642 
3643 		/* also, we should cover whole original request */
3644 		wins = EXT4_C2B(sbi, ac->ac_b_ex.fe_len - ac->ac_o_ex.fe_len);
3645 
3646 		/* the smallest one defines real window */
3647 		win = min(winl, wins);
3648 
3649 		offs = ac->ac_o_ex.fe_logical %
3650 			EXT4_C2B(sbi, ac->ac_b_ex.fe_len);
3651 		if (offs && offs < win)
3652 			win = offs;
3653 
3654 		ac->ac_b_ex.fe_logical = ac->ac_o_ex.fe_logical -
3655 			EXT4_NUM_B2C(sbi, win);
3656 		BUG_ON(ac->ac_o_ex.fe_logical < ac->ac_b_ex.fe_logical);
3657 		BUG_ON(ac->ac_o_ex.fe_len > ac->ac_b_ex.fe_len);
3658 	}
3659 
3660 	/* preallocation can change ac_b_ex, thus we store actually
3661 	 * allocated blocks for history */
3662 	ac->ac_f_ex = ac->ac_b_ex;
3663 
3664 	pa->pa_lstart = ac->ac_b_ex.fe_logical;
3665 	pa->pa_pstart = ext4_grp_offs_to_block(sb, &ac->ac_b_ex);
3666 	pa->pa_len = ac->ac_b_ex.fe_len;
3667 	pa->pa_free = pa->pa_len;
3668 	atomic_set(&pa->pa_count, 1);
3669 	spin_lock_init(&pa->pa_lock);
3670 	INIT_LIST_HEAD(&pa->pa_inode_list);
3671 	INIT_LIST_HEAD(&pa->pa_group_list);
3672 	pa->pa_deleted = 0;
3673 	pa->pa_type = MB_INODE_PA;
3674 
3675 	mb_debug(1, "new inode pa %p: %llu/%u for %u\n", pa,
3676 			pa->pa_pstart, pa->pa_len, pa->pa_lstart);
3677 	trace_ext4_mb_new_inode_pa(ac, pa);
3678 
3679 	ext4_mb_use_inode_pa(ac, pa);
3680 	atomic_add(pa->pa_free, &sbi->s_mb_preallocated);
3681 
3682 	ei = EXT4_I(ac->ac_inode);
3683 	grp = ext4_get_group_info(sb, ac->ac_b_ex.fe_group);
3684 
3685 	pa->pa_obj_lock = &ei->i_prealloc_lock;
3686 	pa->pa_inode = ac->ac_inode;
3687 
3688 	ext4_lock_group(sb, ac->ac_b_ex.fe_group);
3689 	list_add(&pa->pa_group_list, &grp->bb_prealloc_list);
3690 	ext4_unlock_group(sb, ac->ac_b_ex.fe_group);
3691 
3692 	spin_lock(pa->pa_obj_lock);
3693 	list_add_rcu(&pa->pa_inode_list, &ei->i_prealloc_list);
3694 	spin_unlock(pa->pa_obj_lock);
3695 
3696 	return 0;
3697 }
3698 
3699 /*
3700  * creates new preallocated space for locality group inodes belongs to
3701  */
3702 static noinline_for_stack int
3703 ext4_mb_new_group_pa(struct ext4_allocation_context *ac)
3704 {
3705 	struct super_block *sb = ac->ac_sb;
3706 	struct ext4_locality_group *lg;
3707 	struct ext4_prealloc_space *pa;
3708 	struct ext4_group_info *grp;
3709 
3710 	/* preallocate only when found space is larger then requested */
3711 	BUG_ON(ac->ac_o_ex.fe_len >= ac->ac_b_ex.fe_len);
3712 	BUG_ON(ac->ac_status != AC_STATUS_FOUND);
3713 	BUG_ON(!S_ISREG(ac->ac_inode->i_mode));
3714 
3715 	BUG_ON(ext4_pspace_cachep == NULL);
3716 	pa = kmem_cache_alloc(ext4_pspace_cachep, GFP_NOFS);
3717 	if (pa == NULL)
3718 		return -ENOMEM;
3719 
3720 	/* preallocation can change ac_b_ex, thus we store actually
3721 	 * allocated blocks for history */
3722 	ac->ac_f_ex = ac->ac_b_ex;
3723 
3724 	pa->pa_pstart = ext4_grp_offs_to_block(sb, &ac->ac_b_ex);
3725 	pa->pa_lstart = pa->pa_pstart;
3726 	pa->pa_len = ac->ac_b_ex.fe_len;
3727 	pa->pa_free = pa->pa_len;
3728 	atomic_set(&pa->pa_count, 1);
3729 	spin_lock_init(&pa->pa_lock);
3730 	INIT_LIST_HEAD(&pa->pa_inode_list);
3731 	INIT_LIST_HEAD(&pa->pa_group_list);
3732 	pa->pa_deleted = 0;
3733 	pa->pa_type = MB_GROUP_PA;
3734 
3735 	mb_debug(1, "new group pa %p: %llu/%u for %u\n", pa,
3736 			pa->pa_pstart, pa->pa_len, pa->pa_lstart);
3737 	trace_ext4_mb_new_group_pa(ac, pa);
3738 
3739 	ext4_mb_use_group_pa(ac, pa);
3740 	atomic_add(pa->pa_free, &EXT4_SB(sb)->s_mb_preallocated);
3741 
3742 	grp = ext4_get_group_info(sb, ac->ac_b_ex.fe_group);
3743 	lg = ac->ac_lg;
3744 	BUG_ON(lg == NULL);
3745 
3746 	pa->pa_obj_lock = &lg->lg_prealloc_lock;
3747 	pa->pa_inode = NULL;
3748 
3749 	ext4_lock_group(sb, ac->ac_b_ex.fe_group);
3750 	list_add(&pa->pa_group_list, &grp->bb_prealloc_list);
3751 	ext4_unlock_group(sb, ac->ac_b_ex.fe_group);
3752 
3753 	/*
3754 	 * We will later add the new pa to the right bucket
3755 	 * after updating the pa_free in ext4_mb_release_context
3756 	 */
3757 	return 0;
3758 }
3759 
3760 static int ext4_mb_new_preallocation(struct ext4_allocation_context *ac)
3761 {
3762 	int err;
3763 
3764 	if (ac->ac_flags & EXT4_MB_HINT_GROUP_ALLOC)
3765 		err = ext4_mb_new_group_pa(ac);
3766 	else
3767 		err = ext4_mb_new_inode_pa(ac);
3768 	return err;
3769 }
3770 
3771 /*
3772  * finds all unused blocks in on-disk bitmap, frees them in
3773  * in-core bitmap and buddy.
3774  * @pa must be unlinked from inode and group lists, so that
3775  * nobody else can find/use it.
3776  * the caller MUST hold group/inode locks.
3777  * TODO: optimize the case when there are no in-core structures yet
3778  */
3779 static noinline_for_stack int
3780 ext4_mb_release_inode_pa(struct ext4_buddy *e4b, struct buffer_head *bitmap_bh,
3781 			struct ext4_prealloc_space *pa)
3782 {
3783 	struct super_block *sb = e4b->bd_sb;
3784 	struct ext4_sb_info *sbi = EXT4_SB(sb);
3785 	unsigned int end;
3786 	unsigned int next;
3787 	ext4_group_t group;
3788 	ext4_grpblk_t bit;
3789 	unsigned long long grp_blk_start;
3790 	int err = 0;
3791 	int free = 0;
3792 
3793 	BUG_ON(pa->pa_deleted == 0);
3794 	ext4_get_group_no_and_offset(sb, pa->pa_pstart, &group, &bit);
3795 	grp_blk_start = pa->pa_pstart - EXT4_C2B(sbi, bit);
3796 	BUG_ON(group != e4b->bd_group && pa->pa_len != 0);
3797 	end = bit + pa->pa_len;
3798 
3799 	while (bit < end) {
3800 		bit = mb_find_next_zero_bit(bitmap_bh->b_data, end, bit);
3801 		if (bit >= end)
3802 			break;
3803 		next = mb_find_next_bit(bitmap_bh->b_data, end, bit);
3804 		mb_debug(1, "    free preallocated %u/%u in group %u\n",
3805 			 (unsigned) ext4_group_first_block_no(sb, group) + bit,
3806 			 (unsigned) next - bit, (unsigned) group);
3807 		free += next - bit;
3808 
3809 		trace_ext4_mballoc_discard(sb, NULL, group, bit, next - bit);
3810 		trace_ext4_mb_release_inode_pa(pa, (grp_blk_start +
3811 						    EXT4_C2B(sbi, bit)),
3812 					       next - bit);
3813 		mb_free_blocks(pa->pa_inode, e4b, bit, next - bit);
3814 		bit = next + 1;
3815 	}
3816 	if (free != pa->pa_free) {
3817 		ext4_msg(e4b->bd_sb, KERN_CRIT,
3818 			 "pa %p: logic %lu, phys. %lu, len %lu",
3819 			 pa, (unsigned long) pa->pa_lstart,
3820 			 (unsigned long) pa->pa_pstart,
3821 			 (unsigned long) pa->pa_len);
3822 		ext4_grp_locked_error(sb, group, 0, 0, "free %u, pa_free %u",
3823 					free, pa->pa_free);
3824 		/*
3825 		 * pa is already deleted so we use the value obtained
3826 		 * from the bitmap and continue.
3827 		 */
3828 	}
3829 	atomic_add(free, &sbi->s_mb_discarded);
3830 
3831 	return err;
3832 }
3833 
3834 static noinline_for_stack int
3835 ext4_mb_release_group_pa(struct ext4_buddy *e4b,
3836 				struct ext4_prealloc_space *pa)
3837 {
3838 	struct super_block *sb = e4b->bd_sb;
3839 	ext4_group_t group;
3840 	ext4_grpblk_t bit;
3841 
3842 	trace_ext4_mb_release_group_pa(sb, pa);
3843 	BUG_ON(pa->pa_deleted == 0);
3844 	ext4_get_group_no_and_offset(sb, pa->pa_pstart, &group, &bit);
3845 	BUG_ON(group != e4b->bd_group && pa->pa_len != 0);
3846 	mb_free_blocks(pa->pa_inode, e4b, bit, pa->pa_len);
3847 	atomic_add(pa->pa_len, &EXT4_SB(sb)->s_mb_discarded);
3848 	trace_ext4_mballoc_discard(sb, NULL, group, bit, pa->pa_len);
3849 
3850 	return 0;
3851 }
3852 
3853 /*
3854  * releases all preallocations in given group
3855  *
3856  * first, we need to decide discard policy:
3857  * - when do we discard
3858  *   1) ENOSPC
3859  * - how many do we discard
3860  *   1) how many requested
3861  */
3862 static noinline_for_stack int
3863 ext4_mb_discard_group_preallocations(struct super_block *sb,
3864 					ext4_group_t group, int needed)
3865 {
3866 	struct ext4_group_info *grp = ext4_get_group_info(sb, group);
3867 	struct buffer_head *bitmap_bh = NULL;
3868 	struct ext4_prealloc_space *pa, *tmp;
3869 	struct list_head list;
3870 	struct ext4_buddy e4b;
3871 	int err;
3872 	int busy = 0;
3873 	int free = 0;
3874 
3875 	mb_debug(1, "discard preallocation for group %u\n", group);
3876 
3877 	if (list_empty(&grp->bb_prealloc_list))
3878 		return 0;
3879 
3880 	bitmap_bh = ext4_read_block_bitmap(sb, group);
3881 	if (IS_ERR(bitmap_bh)) {
3882 		err = PTR_ERR(bitmap_bh);
3883 		ext4_error(sb, "Error %d reading block bitmap for %u",
3884 			   err, group);
3885 		return 0;
3886 	}
3887 
3888 	err = ext4_mb_load_buddy(sb, group, &e4b);
3889 	if (err) {
3890 		ext4_error(sb, "Error loading buddy information for %u", group);
3891 		put_bh(bitmap_bh);
3892 		return 0;
3893 	}
3894 
3895 	if (needed == 0)
3896 		needed = EXT4_CLUSTERS_PER_GROUP(sb) + 1;
3897 
3898 	INIT_LIST_HEAD(&list);
3899 repeat:
3900 	ext4_lock_group(sb, group);
3901 	list_for_each_entry_safe(pa, tmp,
3902 				&grp->bb_prealloc_list, pa_group_list) {
3903 		spin_lock(&pa->pa_lock);
3904 		if (atomic_read(&pa->pa_count)) {
3905 			spin_unlock(&pa->pa_lock);
3906 			busy = 1;
3907 			continue;
3908 		}
3909 		if (pa->pa_deleted) {
3910 			spin_unlock(&pa->pa_lock);
3911 			continue;
3912 		}
3913 
3914 		/* seems this one can be freed ... */
3915 		pa->pa_deleted = 1;
3916 
3917 		/* we can trust pa_free ... */
3918 		free += pa->pa_free;
3919 
3920 		spin_unlock(&pa->pa_lock);
3921 
3922 		list_del(&pa->pa_group_list);
3923 		list_add(&pa->u.pa_tmp_list, &list);
3924 	}
3925 
3926 	/* if we still need more blocks and some PAs were used, try again */
3927 	if (free < needed && busy) {
3928 		busy = 0;
3929 		ext4_unlock_group(sb, group);
3930 		cond_resched();
3931 		goto repeat;
3932 	}
3933 
3934 	/* found anything to free? */
3935 	if (list_empty(&list)) {
3936 		BUG_ON(free != 0);
3937 		goto out;
3938 	}
3939 
3940 	/* now free all selected PAs */
3941 	list_for_each_entry_safe(pa, tmp, &list, u.pa_tmp_list) {
3942 
3943 		/* remove from object (inode or locality group) */
3944 		spin_lock(pa->pa_obj_lock);
3945 		list_del_rcu(&pa->pa_inode_list);
3946 		spin_unlock(pa->pa_obj_lock);
3947 
3948 		if (pa->pa_type == MB_GROUP_PA)
3949 			ext4_mb_release_group_pa(&e4b, pa);
3950 		else
3951 			ext4_mb_release_inode_pa(&e4b, bitmap_bh, pa);
3952 
3953 		list_del(&pa->u.pa_tmp_list);
3954 		call_rcu(&(pa)->u.pa_rcu, ext4_mb_pa_callback);
3955 	}
3956 
3957 out:
3958 	ext4_unlock_group(sb, group);
3959 	ext4_mb_unload_buddy(&e4b);
3960 	put_bh(bitmap_bh);
3961 	return free;
3962 }
3963 
3964 /*
3965  * releases all non-used preallocated blocks for given inode
3966  *
3967  * It's important to discard preallocations under i_data_sem
3968  * We don't want another block to be served from the prealloc
3969  * space when we are discarding the inode prealloc space.
3970  *
3971  * FIXME!! Make sure it is valid at all the call sites
3972  */
3973 void ext4_discard_preallocations(struct inode *inode)
3974 {
3975 	struct ext4_inode_info *ei = EXT4_I(inode);
3976 	struct super_block *sb = inode->i_sb;
3977 	struct buffer_head *bitmap_bh = NULL;
3978 	struct ext4_prealloc_space *pa, *tmp;
3979 	ext4_group_t group = 0;
3980 	struct list_head list;
3981 	struct ext4_buddy e4b;
3982 	int err;
3983 
3984 	if (!S_ISREG(inode->i_mode)) {
3985 		/*BUG_ON(!list_empty(&ei->i_prealloc_list));*/
3986 		return;
3987 	}
3988 
3989 	mb_debug(1, "discard preallocation for inode %lu\n", inode->i_ino);
3990 	trace_ext4_discard_preallocations(inode);
3991 
3992 	INIT_LIST_HEAD(&list);
3993 
3994 repeat:
3995 	/* first, collect all pa's in the inode */
3996 	spin_lock(&ei->i_prealloc_lock);
3997 	while (!list_empty(&ei->i_prealloc_list)) {
3998 		pa = list_entry(ei->i_prealloc_list.next,
3999 				struct ext4_prealloc_space, pa_inode_list);
4000 		BUG_ON(pa->pa_obj_lock != &ei->i_prealloc_lock);
4001 		spin_lock(&pa->pa_lock);
4002 		if (atomic_read(&pa->pa_count)) {
4003 			/* this shouldn't happen often - nobody should
4004 			 * use preallocation while we're discarding it */
4005 			spin_unlock(&pa->pa_lock);
4006 			spin_unlock(&ei->i_prealloc_lock);
4007 			ext4_msg(sb, KERN_ERR,
4008 				 "uh-oh! used pa while discarding");
4009 			WARN_ON(1);
4010 			schedule_timeout_uninterruptible(HZ);
4011 			goto repeat;
4012 
4013 		}
4014 		if (pa->pa_deleted == 0) {
4015 			pa->pa_deleted = 1;
4016 			spin_unlock(&pa->pa_lock);
4017 			list_del_rcu(&pa->pa_inode_list);
4018 			list_add(&pa->u.pa_tmp_list, &list);
4019 			continue;
4020 		}
4021 
4022 		/* someone is deleting pa right now */
4023 		spin_unlock(&pa->pa_lock);
4024 		spin_unlock(&ei->i_prealloc_lock);
4025 
4026 		/* we have to wait here because pa_deleted
4027 		 * doesn't mean pa is already unlinked from
4028 		 * the list. as we might be called from
4029 		 * ->clear_inode() the inode will get freed
4030 		 * and concurrent thread which is unlinking
4031 		 * pa from inode's list may access already
4032 		 * freed memory, bad-bad-bad */
4033 
4034 		/* XXX: if this happens too often, we can
4035 		 * add a flag to force wait only in case
4036 		 * of ->clear_inode(), but not in case of
4037 		 * regular truncate */
4038 		schedule_timeout_uninterruptible(HZ);
4039 		goto repeat;
4040 	}
4041 	spin_unlock(&ei->i_prealloc_lock);
4042 
4043 	list_for_each_entry_safe(pa, tmp, &list, u.pa_tmp_list) {
4044 		BUG_ON(pa->pa_type != MB_INODE_PA);
4045 		group = ext4_get_group_number(sb, pa->pa_pstart);
4046 
4047 		err = ext4_mb_load_buddy(sb, group, &e4b);
4048 		if (err) {
4049 			ext4_error(sb, "Error loading buddy information for %u",
4050 					group);
4051 			continue;
4052 		}
4053 
4054 		bitmap_bh = ext4_read_block_bitmap(sb, group);
4055 		if (IS_ERR(bitmap_bh)) {
4056 			err = PTR_ERR(bitmap_bh);
4057 			ext4_error(sb, "Error %d reading block bitmap for %u",
4058 					err, group);
4059 			ext4_mb_unload_buddy(&e4b);
4060 			continue;
4061 		}
4062 
4063 		ext4_lock_group(sb, group);
4064 		list_del(&pa->pa_group_list);
4065 		ext4_mb_release_inode_pa(&e4b, bitmap_bh, pa);
4066 		ext4_unlock_group(sb, group);
4067 
4068 		ext4_mb_unload_buddy(&e4b);
4069 		put_bh(bitmap_bh);
4070 
4071 		list_del(&pa->u.pa_tmp_list);
4072 		call_rcu(&(pa)->u.pa_rcu, ext4_mb_pa_callback);
4073 	}
4074 }
4075 
4076 #ifdef CONFIG_EXT4_DEBUG
4077 static void ext4_mb_show_ac(struct ext4_allocation_context *ac)
4078 {
4079 	struct super_block *sb = ac->ac_sb;
4080 	ext4_group_t ngroups, i;
4081 
4082 	if (!ext4_mballoc_debug ||
4083 	    (EXT4_SB(sb)->s_mount_flags & EXT4_MF_FS_ABORTED))
4084 		return;
4085 
4086 	ext4_msg(ac->ac_sb, KERN_ERR, "Can't allocate:"
4087 			" Allocation context details:");
4088 	ext4_msg(ac->ac_sb, KERN_ERR, "status %d flags %d",
4089 			ac->ac_status, ac->ac_flags);
4090 	ext4_msg(ac->ac_sb, KERN_ERR, "orig %lu/%lu/%lu@%lu, "
4091 		 	"goal %lu/%lu/%lu@%lu, "
4092 			"best %lu/%lu/%lu@%lu cr %d",
4093 			(unsigned long)ac->ac_o_ex.fe_group,
4094 			(unsigned long)ac->ac_o_ex.fe_start,
4095 			(unsigned long)ac->ac_o_ex.fe_len,
4096 			(unsigned long)ac->ac_o_ex.fe_logical,
4097 			(unsigned long)ac->ac_g_ex.fe_group,
4098 			(unsigned long)ac->ac_g_ex.fe_start,
4099 			(unsigned long)ac->ac_g_ex.fe_len,
4100 			(unsigned long)ac->ac_g_ex.fe_logical,
4101 			(unsigned long)ac->ac_b_ex.fe_group,
4102 			(unsigned long)ac->ac_b_ex.fe_start,
4103 			(unsigned long)ac->ac_b_ex.fe_len,
4104 			(unsigned long)ac->ac_b_ex.fe_logical,
4105 			(int)ac->ac_criteria);
4106 	ext4_msg(ac->ac_sb, KERN_ERR, "%d found", ac->ac_found);
4107 	ext4_msg(ac->ac_sb, KERN_ERR, "groups: ");
4108 	ngroups = ext4_get_groups_count(sb);
4109 	for (i = 0; i < ngroups; i++) {
4110 		struct ext4_group_info *grp = ext4_get_group_info(sb, i);
4111 		struct ext4_prealloc_space *pa;
4112 		ext4_grpblk_t start;
4113 		struct list_head *cur;
4114 		ext4_lock_group(sb, i);
4115 		list_for_each(cur, &grp->bb_prealloc_list) {
4116 			pa = list_entry(cur, struct ext4_prealloc_space,
4117 					pa_group_list);
4118 			spin_lock(&pa->pa_lock);
4119 			ext4_get_group_no_and_offset(sb, pa->pa_pstart,
4120 						     NULL, &start);
4121 			spin_unlock(&pa->pa_lock);
4122 			printk(KERN_ERR "PA:%u:%d:%u \n", i,
4123 			       start, pa->pa_len);
4124 		}
4125 		ext4_unlock_group(sb, i);
4126 
4127 		if (grp->bb_free == 0)
4128 			continue;
4129 		printk(KERN_ERR "%u: %d/%d \n",
4130 		       i, grp->bb_free, grp->bb_fragments);
4131 	}
4132 	printk(KERN_ERR "\n");
4133 }
4134 #else
4135 static inline void ext4_mb_show_ac(struct ext4_allocation_context *ac)
4136 {
4137 	return;
4138 }
4139 #endif
4140 
4141 /*
4142  * We use locality group preallocation for small size file. The size of the
4143  * file is determined by the current size or the resulting size after
4144  * allocation which ever is larger
4145  *
4146  * One can tune this size via /sys/fs/ext4/<partition>/mb_stream_req
4147  */
4148 static void ext4_mb_group_or_file(struct ext4_allocation_context *ac)
4149 {
4150 	struct ext4_sb_info *sbi = EXT4_SB(ac->ac_sb);
4151 	int bsbits = ac->ac_sb->s_blocksize_bits;
4152 	loff_t size, isize;
4153 
4154 	if (!(ac->ac_flags & EXT4_MB_HINT_DATA))
4155 		return;
4156 
4157 	if (unlikely(ac->ac_flags & EXT4_MB_HINT_GOAL_ONLY))
4158 		return;
4159 
4160 	size = ac->ac_o_ex.fe_logical + EXT4_C2B(sbi, ac->ac_o_ex.fe_len);
4161 	isize = (i_size_read(ac->ac_inode) + ac->ac_sb->s_blocksize - 1)
4162 		>> bsbits;
4163 
4164 	if ((size == isize) &&
4165 	    !ext4_fs_is_busy(sbi) &&
4166 	    (atomic_read(&ac->ac_inode->i_writecount) == 0)) {
4167 		ac->ac_flags |= EXT4_MB_HINT_NOPREALLOC;
4168 		return;
4169 	}
4170 
4171 	if (sbi->s_mb_group_prealloc <= 0) {
4172 		ac->ac_flags |= EXT4_MB_STREAM_ALLOC;
4173 		return;
4174 	}
4175 
4176 	/* don't use group allocation for large files */
4177 	size = max(size, isize);
4178 	if (size > sbi->s_mb_stream_request) {
4179 		ac->ac_flags |= EXT4_MB_STREAM_ALLOC;
4180 		return;
4181 	}
4182 
4183 	BUG_ON(ac->ac_lg != NULL);
4184 	/*
4185 	 * locality group prealloc space are per cpu. The reason for having
4186 	 * per cpu locality group is to reduce the contention between block
4187 	 * request from multiple CPUs.
4188 	 */
4189 	ac->ac_lg = raw_cpu_ptr(sbi->s_locality_groups);
4190 
4191 	/* we're going to use group allocation */
4192 	ac->ac_flags |= EXT4_MB_HINT_GROUP_ALLOC;
4193 
4194 	/* serialize all allocations in the group */
4195 	mutex_lock(&ac->ac_lg->lg_mutex);
4196 }
4197 
4198 static noinline_for_stack int
4199 ext4_mb_initialize_context(struct ext4_allocation_context *ac,
4200 				struct ext4_allocation_request *ar)
4201 {
4202 	struct super_block *sb = ar->inode->i_sb;
4203 	struct ext4_sb_info *sbi = EXT4_SB(sb);
4204 	struct ext4_super_block *es = sbi->s_es;
4205 	ext4_group_t group;
4206 	unsigned int len;
4207 	ext4_fsblk_t goal;
4208 	ext4_grpblk_t block;
4209 
4210 	/* we can't allocate > group size */
4211 	len = ar->len;
4212 
4213 	/* just a dirty hack to filter too big requests  */
4214 	if (len >= EXT4_CLUSTERS_PER_GROUP(sb))
4215 		len = EXT4_CLUSTERS_PER_GROUP(sb);
4216 
4217 	/* start searching from the goal */
4218 	goal = ar->goal;
4219 	if (goal < le32_to_cpu(es->s_first_data_block) ||
4220 			goal >= ext4_blocks_count(es))
4221 		goal = le32_to_cpu(es->s_first_data_block);
4222 	ext4_get_group_no_and_offset(sb, goal, &group, &block);
4223 
4224 	/* set up allocation goals */
4225 	ac->ac_b_ex.fe_logical = EXT4_LBLK_CMASK(sbi, ar->logical);
4226 	ac->ac_status = AC_STATUS_CONTINUE;
4227 	ac->ac_sb = sb;
4228 	ac->ac_inode = ar->inode;
4229 	ac->ac_o_ex.fe_logical = ac->ac_b_ex.fe_logical;
4230 	ac->ac_o_ex.fe_group = group;
4231 	ac->ac_o_ex.fe_start = block;
4232 	ac->ac_o_ex.fe_len = len;
4233 	ac->ac_g_ex = ac->ac_o_ex;
4234 	ac->ac_flags = ar->flags;
4235 
4236 	/* we have to define context: we'll we work with a file or
4237 	 * locality group. this is a policy, actually */
4238 	ext4_mb_group_or_file(ac);
4239 
4240 	mb_debug(1, "init ac: %u blocks @ %u, goal %u, flags %x, 2^%d, "
4241 			"left: %u/%u, right %u/%u to %swritable\n",
4242 			(unsigned) ar->len, (unsigned) ar->logical,
4243 			(unsigned) ar->goal, ac->ac_flags, ac->ac_2order,
4244 			(unsigned) ar->lleft, (unsigned) ar->pleft,
4245 			(unsigned) ar->lright, (unsigned) ar->pright,
4246 			atomic_read(&ar->inode->i_writecount) ? "" : "non-");
4247 	return 0;
4248 
4249 }
4250 
4251 static noinline_for_stack void
4252 ext4_mb_discard_lg_preallocations(struct super_block *sb,
4253 					struct ext4_locality_group *lg,
4254 					int order, int total_entries)
4255 {
4256 	ext4_group_t group = 0;
4257 	struct ext4_buddy e4b;
4258 	struct list_head discard_list;
4259 	struct ext4_prealloc_space *pa, *tmp;
4260 
4261 	mb_debug(1, "discard locality group preallocation\n");
4262 
4263 	INIT_LIST_HEAD(&discard_list);
4264 
4265 	spin_lock(&lg->lg_prealloc_lock);
4266 	list_for_each_entry_rcu(pa, &lg->lg_prealloc_list[order],
4267 						pa_inode_list) {
4268 		spin_lock(&pa->pa_lock);
4269 		if (atomic_read(&pa->pa_count)) {
4270 			/*
4271 			 * This is the pa that we just used
4272 			 * for block allocation. So don't
4273 			 * free that
4274 			 */
4275 			spin_unlock(&pa->pa_lock);
4276 			continue;
4277 		}
4278 		if (pa->pa_deleted) {
4279 			spin_unlock(&pa->pa_lock);
4280 			continue;
4281 		}
4282 		/* only lg prealloc space */
4283 		BUG_ON(pa->pa_type != MB_GROUP_PA);
4284 
4285 		/* seems this one can be freed ... */
4286 		pa->pa_deleted = 1;
4287 		spin_unlock(&pa->pa_lock);
4288 
4289 		list_del_rcu(&pa->pa_inode_list);
4290 		list_add(&pa->u.pa_tmp_list, &discard_list);
4291 
4292 		total_entries--;
4293 		if (total_entries <= 5) {
4294 			/*
4295 			 * we want to keep only 5 entries
4296 			 * allowing it to grow to 8. This
4297 			 * mak sure we don't call discard
4298 			 * soon for this list.
4299 			 */
4300 			break;
4301 		}
4302 	}
4303 	spin_unlock(&lg->lg_prealloc_lock);
4304 
4305 	list_for_each_entry_safe(pa, tmp, &discard_list, u.pa_tmp_list) {
4306 
4307 		group = ext4_get_group_number(sb, pa->pa_pstart);
4308 		if (ext4_mb_load_buddy(sb, group, &e4b)) {
4309 			ext4_error(sb, "Error loading buddy information for %u",
4310 					group);
4311 			continue;
4312 		}
4313 		ext4_lock_group(sb, group);
4314 		list_del(&pa->pa_group_list);
4315 		ext4_mb_release_group_pa(&e4b, pa);
4316 		ext4_unlock_group(sb, group);
4317 
4318 		ext4_mb_unload_buddy(&e4b);
4319 		list_del(&pa->u.pa_tmp_list);
4320 		call_rcu(&(pa)->u.pa_rcu, ext4_mb_pa_callback);
4321 	}
4322 }
4323 
4324 /*
4325  * We have incremented pa_count. So it cannot be freed at this
4326  * point. Also we hold lg_mutex. So no parallel allocation is
4327  * possible from this lg. That means pa_free cannot be updated.
4328  *
4329  * A parallel ext4_mb_discard_group_preallocations is possible.
4330  * which can cause the lg_prealloc_list to be updated.
4331  */
4332 
4333 static void ext4_mb_add_n_trim(struct ext4_allocation_context *ac)
4334 {
4335 	int order, added = 0, lg_prealloc_count = 1;
4336 	struct super_block *sb = ac->ac_sb;
4337 	struct ext4_locality_group *lg = ac->ac_lg;
4338 	struct ext4_prealloc_space *tmp_pa, *pa = ac->ac_pa;
4339 
4340 	order = fls(pa->pa_free) - 1;
4341 	if (order > PREALLOC_TB_SIZE - 1)
4342 		/* The max size of hash table is PREALLOC_TB_SIZE */
4343 		order = PREALLOC_TB_SIZE - 1;
4344 	/* Add the prealloc space to lg */
4345 	spin_lock(&lg->lg_prealloc_lock);
4346 	list_for_each_entry_rcu(tmp_pa, &lg->lg_prealloc_list[order],
4347 						pa_inode_list) {
4348 		spin_lock(&tmp_pa->pa_lock);
4349 		if (tmp_pa->pa_deleted) {
4350 			spin_unlock(&tmp_pa->pa_lock);
4351 			continue;
4352 		}
4353 		if (!added && pa->pa_free < tmp_pa->pa_free) {
4354 			/* Add to the tail of the previous entry */
4355 			list_add_tail_rcu(&pa->pa_inode_list,
4356 						&tmp_pa->pa_inode_list);
4357 			added = 1;
4358 			/*
4359 			 * we want to count the total
4360 			 * number of entries in the list
4361 			 */
4362 		}
4363 		spin_unlock(&tmp_pa->pa_lock);
4364 		lg_prealloc_count++;
4365 	}
4366 	if (!added)
4367 		list_add_tail_rcu(&pa->pa_inode_list,
4368 					&lg->lg_prealloc_list[order]);
4369 	spin_unlock(&lg->lg_prealloc_lock);
4370 
4371 	/* Now trim the list to be not more than 8 elements */
4372 	if (lg_prealloc_count > 8) {
4373 		ext4_mb_discard_lg_preallocations(sb, lg,
4374 						  order, lg_prealloc_count);
4375 		return;
4376 	}
4377 	return ;
4378 }
4379 
4380 /*
4381  * release all resource we used in allocation
4382  */
4383 static int ext4_mb_release_context(struct ext4_allocation_context *ac)
4384 {
4385 	struct ext4_sb_info *sbi = EXT4_SB(ac->ac_sb);
4386 	struct ext4_prealloc_space *pa = ac->ac_pa;
4387 	if (pa) {
4388 		if (pa->pa_type == MB_GROUP_PA) {
4389 			/* see comment in ext4_mb_use_group_pa() */
4390 			spin_lock(&pa->pa_lock);
4391 			pa->pa_pstart += EXT4_C2B(sbi, ac->ac_b_ex.fe_len);
4392 			pa->pa_lstart += EXT4_C2B(sbi, ac->ac_b_ex.fe_len);
4393 			pa->pa_free -= ac->ac_b_ex.fe_len;
4394 			pa->pa_len -= ac->ac_b_ex.fe_len;
4395 			spin_unlock(&pa->pa_lock);
4396 		}
4397 	}
4398 	if (pa) {
4399 		/*
4400 		 * We want to add the pa to the right bucket.
4401 		 * Remove it from the list and while adding
4402 		 * make sure the list to which we are adding
4403 		 * doesn't grow big.
4404 		 */
4405 		if ((pa->pa_type == MB_GROUP_PA) && likely(pa->pa_free)) {
4406 			spin_lock(pa->pa_obj_lock);
4407 			list_del_rcu(&pa->pa_inode_list);
4408 			spin_unlock(pa->pa_obj_lock);
4409 			ext4_mb_add_n_trim(ac);
4410 		}
4411 		ext4_mb_put_pa(ac, ac->ac_sb, pa);
4412 	}
4413 	if (ac->ac_bitmap_page)
4414 		put_page(ac->ac_bitmap_page);
4415 	if (ac->ac_buddy_page)
4416 		put_page(ac->ac_buddy_page);
4417 	if (ac->ac_flags & EXT4_MB_HINT_GROUP_ALLOC)
4418 		mutex_unlock(&ac->ac_lg->lg_mutex);
4419 	ext4_mb_collect_stats(ac);
4420 	return 0;
4421 }
4422 
4423 static int ext4_mb_discard_preallocations(struct super_block *sb, int needed)
4424 {
4425 	ext4_group_t i, ngroups = ext4_get_groups_count(sb);
4426 	int ret;
4427 	int freed = 0;
4428 
4429 	trace_ext4_mb_discard_preallocations(sb, needed);
4430 	for (i = 0; i < ngroups && needed > 0; i++) {
4431 		ret = ext4_mb_discard_group_preallocations(sb, i, needed);
4432 		freed += ret;
4433 		needed -= ret;
4434 	}
4435 
4436 	return freed;
4437 }
4438 
4439 /*
4440  * Main entry point into mballoc to allocate blocks
4441  * it tries to use preallocation first, then falls back
4442  * to usual allocation
4443  */
4444 ext4_fsblk_t ext4_mb_new_blocks(handle_t *handle,
4445 				struct ext4_allocation_request *ar, int *errp)
4446 {
4447 	int freed;
4448 	struct ext4_allocation_context *ac = NULL;
4449 	struct ext4_sb_info *sbi;
4450 	struct super_block *sb;
4451 	ext4_fsblk_t block = 0;
4452 	unsigned int inquota = 0;
4453 	unsigned int reserv_clstrs = 0;
4454 
4455 	might_sleep();
4456 	sb = ar->inode->i_sb;
4457 	sbi = EXT4_SB(sb);
4458 
4459 	trace_ext4_request_blocks(ar);
4460 
4461 	/* Allow to use superuser reservation for quota file */
4462 	if (IS_NOQUOTA(ar->inode))
4463 		ar->flags |= EXT4_MB_USE_ROOT_BLOCKS;
4464 
4465 	if ((ar->flags & EXT4_MB_DELALLOC_RESERVED) == 0) {
4466 		/* Without delayed allocation we need to verify
4467 		 * there is enough free blocks to do block allocation
4468 		 * and verify allocation doesn't exceed the quota limits.
4469 		 */
4470 		while (ar->len &&
4471 			ext4_claim_free_clusters(sbi, ar->len, ar->flags)) {
4472 
4473 			/* let others to free the space */
4474 			cond_resched();
4475 			ar->len = ar->len >> 1;
4476 		}
4477 		if (!ar->len) {
4478 			*errp = -ENOSPC;
4479 			return 0;
4480 		}
4481 		reserv_clstrs = ar->len;
4482 		if (ar->flags & EXT4_MB_USE_ROOT_BLOCKS) {
4483 			dquot_alloc_block_nofail(ar->inode,
4484 						 EXT4_C2B(sbi, ar->len));
4485 		} else {
4486 			while (ar->len &&
4487 				dquot_alloc_block(ar->inode,
4488 						  EXT4_C2B(sbi, ar->len))) {
4489 
4490 				ar->flags |= EXT4_MB_HINT_NOPREALLOC;
4491 				ar->len--;
4492 			}
4493 		}
4494 		inquota = ar->len;
4495 		if (ar->len == 0) {
4496 			*errp = -EDQUOT;
4497 			goto out;
4498 		}
4499 	}
4500 
4501 	ac = kmem_cache_zalloc(ext4_ac_cachep, GFP_NOFS);
4502 	if (!ac) {
4503 		ar->len = 0;
4504 		*errp = -ENOMEM;
4505 		goto out;
4506 	}
4507 
4508 	*errp = ext4_mb_initialize_context(ac, ar);
4509 	if (*errp) {
4510 		ar->len = 0;
4511 		goto out;
4512 	}
4513 
4514 	ac->ac_op = EXT4_MB_HISTORY_PREALLOC;
4515 	if (!ext4_mb_use_preallocated(ac)) {
4516 		ac->ac_op = EXT4_MB_HISTORY_ALLOC;
4517 		ext4_mb_normalize_request(ac, ar);
4518 repeat:
4519 		/* allocate space in core */
4520 		*errp = ext4_mb_regular_allocator(ac);
4521 		if (*errp)
4522 			goto discard_and_exit;
4523 
4524 		/* as we've just preallocated more space than
4525 		 * user requested originally, we store allocated
4526 		 * space in a special descriptor */
4527 		if (ac->ac_status == AC_STATUS_FOUND &&
4528 		    ac->ac_o_ex.fe_len < ac->ac_b_ex.fe_len)
4529 			*errp = ext4_mb_new_preallocation(ac);
4530 		if (*errp) {
4531 		discard_and_exit:
4532 			ext4_discard_allocated_blocks(ac);
4533 			goto errout;
4534 		}
4535 	}
4536 	if (likely(ac->ac_status == AC_STATUS_FOUND)) {
4537 		*errp = ext4_mb_mark_diskspace_used(ac, handle, reserv_clstrs);
4538 		if (*errp) {
4539 			ext4_discard_allocated_blocks(ac);
4540 			goto errout;
4541 		} else {
4542 			block = ext4_grp_offs_to_block(sb, &ac->ac_b_ex);
4543 			ar->len = ac->ac_b_ex.fe_len;
4544 		}
4545 	} else {
4546 		freed  = ext4_mb_discard_preallocations(sb, ac->ac_o_ex.fe_len);
4547 		if (freed)
4548 			goto repeat;
4549 		*errp = -ENOSPC;
4550 	}
4551 
4552 errout:
4553 	if (*errp) {
4554 		ac->ac_b_ex.fe_len = 0;
4555 		ar->len = 0;
4556 		ext4_mb_show_ac(ac);
4557 	}
4558 	ext4_mb_release_context(ac);
4559 out:
4560 	if (ac)
4561 		kmem_cache_free(ext4_ac_cachep, ac);
4562 	if (inquota && ar->len < inquota)
4563 		dquot_free_block(ar->inode, EXT4_C2B(sbi, inquota - ar->len));
4564 	if (!ar->len) {
4565 		if ((ar->flags & EXT4_MB_DELALLOC_RESERVED) == 0)
4566 			/* release all the reserved blocks if non delalloc */
4567 			percpu_counter_sub(&sbi->s_dirtyclusters_counter,
4568 						reserv_clstrs);
4569 	}
4570 
4571 	trace_ext4_allocate_blocks(ar, (unsigned long long)block);
4572 
4573 	return block;
4574 }
4575 
4576 /*
4577  * We can merge two free data extents only if the physical blocks
4578  * are contiguous, AND the extents were freed by the same transaction,
4579  * AND the blocks are associated with the same group.
4580  */
4581 static int can_merge(struct ext4_free_data *entry1,
4582 			struct ext4_free_data *entry2)
4583 {
4584 	if ((entry1->efd_tid == entry2->efd_tid) &&
4585 	    (entry1->efd_group == entry2->efd_group) &&
4586 	    ((entry1->efd_start_cluster + entry1->efd_count) == entry2->efd_start_cluster))
4587 		return 1;
4588 	return 0;
4589 }
4590 
4591 static noinline_for_stack int
4592 ext4_mb_free_metadata(handle_t *handle, struct ext4_buddy *e4b,
4593 		      struct ext4_free_data *new_entry)
4594 {
4595 	ext4_group_t group = e4b->bd_group;
4596 	ext4_grpblk_t cluster;
4597 	ext4_grpblk_t clusters = new_entry->efd_count;
4598 	struct ext4_free_data *entry;
4599 	struct ext4_group_info *db = e4b->bd_info;
4600 	struct super_block *sb = e4b->bd_sb;
4601 	struct ext4_sb_info *sbi = EXT4_SB(sb);
4602 	struct rb_node **n = &db->bb_free_root.rb_node, *node;
4603 	struct rb_node *parent = NULL, *new_node;
4604 
4605 	BUG_ON(!ext4_handle_valid(handle));
4606 	BUG_ON(e4b->bd_bitmap_page == NULL);
4607 	BUG_ON(e4b->bd_buddy_page == NULL);
4608 
4609 	new_node = &new_entry->efd_node;
4610 	cluster = new_entry->efd_start_cluster;
4611 
4612 	if (!*n) {
4613 		/* first free block exent. We need to
4614 		   protect buddy cache from being freed,
4615 		 * otherwise we'll refresh it from
4616 		 * on-disk bitmap and lose not-yet-available
4617 		 * blocks */
4618 		get_page(e4b->bd_buddy_page);
4619 		get_page(e4b->bd_bitmap_page);
4620 	}
4621 	while (*n) {
4622 		parent = *n;
4623 		entry = rb_entry(parent, struct ext4_free_data, efd_node);
4624 		if (cluster < entry->efd_start_cluster)
4625 			n = &(*n)->rb_left;
4626 		else if (cluster >= (entry->efd_start_cluster + entry->efd_count))
4627 			n = &(*n)->rb_right;
4628 		else {
4629 			ext4_grp_locked_error(sb, group, 0,
4630 				ext4_group_first_block_no(sb, group) +
4631 				EXT4_C2B(sbi, cluster),
4632 				"Block already on to-be-freed list");
4633 			return 0;
4634 		}
4635 	}
4636 
4637 	rb_link_node(new_node, parent, n);
4638 	rb_insert_color(new_node, &db->bb_free_root);
4639 
4640 	/* Now try to see the extent can be merged to left and right */
4641 	node = rb_prev(new_node);
4642 	if (node) {
4643 		entry = rb_entry(node, struct ext4_free_data, efd_node);
4644 		if (can_merge(entry, new_entry) &&
4645 		    ext4_journal_callback_try_del(handle, &entry->efd_jce)) {
4646 			new_entry->efd_start_cluster = entry->efd_start_cluster;
4647 			new_entry->efd_count += entry->efd_count;
4648 			rb_erase(node, &(db->bb_free_root));
4649 			kmem_cache_free(ext4_free_data_cachep, entry);
4650 		}
4651 	}
4652 
4653 	node = rb_next(new_node);
4654 	if (node) {
4655 		entry = rb_entry(node, struct ext4_free_data, efd_node);
4656 		if (can_merge(new_entry, entry) &&
4657 		    ext4_journal_callback_try_del(handle, &entry->efd_jce)) {
4658 			new_entry->efd_count += entry->efd_count;
4659 			rb_erase(node, &(db->bb_free_root));
4660 			kmem_cache_free(ext4_free_data_cachep, entry);
4661 		}
4662 	}
4663 	/* Add the extent to transaction's private list */
4664 	new_entry->efd_jce.jce_func = ext4_free_data_callback;
4665 	spin_lock(&sbi->s_md_lock);
4666 	_ext4_journal_callback_add(handle, &new_entry->efd_jce);
4667 	sbi->s_mb_free_pending += clusters;
4668 	spin_unlock(&sbi->s_md_lock);
4669 	return 0;
4670 }
4671 
4672 /**
4673  * ext4_free_blocks() -- Free given blocks and update quota
4674  * @handle:		handle for this transaction
4675  * @inode:		inode
4676  * @block:		start physical block to free
4677  * @count:		number of blocks to count
4678  * @flags:		flags used by ext4_free_blocks
4679  */
4680 void ext4_free_blocks(handle_t *handle, struct inode *inode,
4681 		      struct buffer_head *bh, ext4_fsblk_t block,
4682 		      unsigned long count, int flags)
4683 {
4684 	struct buffer_head *bitmap_bh = NULL;
4685 	struct super_block *sb = inode->i_sb;
4686 	struct ext4_group_desc *gdp;
4687 	unsigned int overflow;
4688 	ext4_grpblk_t bit;
4689 	struct buffer_head *gd_bh;
4690 	ext4_group_t block_group;
4691 	struct ext4_sb_info *sbi;
4692 	struct ext4_buddy e4b;
4693 	unsigned int count_clusters;
4694 	int err = 0;
4695 	int ret;
4696 
4697 	might_sleep();
4698 	if (bh) {
4699 		if (block)
4700 			BUG_ON(block != bh->b_blocknr);
4701 		else
4702 			block = bh->b_blocknr;
4703 	}
4704 
4705 	sbi = EXT4_SB(sb);
4706 	if (!(flags & EXT4_FREE_BLOCKS_VALIDATED) &&
4707 	    !ext4_data_block_valid(sbi, block, count)) {
4708 		ext4_error(sb, "Freeing blocks not in datazone - "
4709 			   "block = %llu, count = %lu", block, count);
4710 		goto error_return;
4711 	}
4712 
4713 	ext4_debug("freeing block %llu\n", block);
4714 	trace_ext4_free_blocks(inode, block, count, flags);
4715 
4716 	if (bh && (flags & EXT4_FREE_BLOCKS_FORGET)) {
4717 		BUG_ON(count > 1);
4718 
4719 		ext4_forget(handle, flags & EXT4_FREE_BLOCKS_METADATA,
4720 			    inode, bh, block);
4721 	}
4722 
4723 	/*
4724 	 * If the extent to be freed does not begin on a cluster
4725 	 * boundary, we need to deal with partial clusters at the
4726 	 * beginning and end of the extent.  Normally we will free
4727 	 * blocks at the beginning or the end unless we are explicitly
4728 	 * requested to avoid doing so.
4729 	 */
4730 	overflow = EXT4_PBLK_COFF(sbi, block);
4731 	if (overflow) {
4732 		if (flags & EXT4_FREE_BLOCKS_NOFREE_FIRST_CLUSTER) {
4733 			overflow = sbi->s_cluster_ratio - overflow;
4734 			block += overflow;
4735 			if (count > overflow)
4736 				count -= overflow;
4737 			else
4738 				return;
4739 		} else {
4740 			block -= overflow;
4741 			count += overflow;
4742 		}
4743 	}
4744 	overflow = EXT4_LBLK_COFF(sbi, count);
4745 	if (overflow) {
4746 		if (flags & EXT4_FREE_BLOCKS_NOFREE_LAST_CLUSTER) {
4747 			if (count > overflow)
4748 				count -= overflow;
4749 			else
4750 				return;
4751 		} else
4752 			count += sbi->s_cluster_ratio - overflow;
4753 	}
4754 
4755 	if (!bh && (flags & EXT4_FREE_BLOCKS_FORGET)) {
4756 		int i;
4757 		int is_metadata = flags & EXT4_FREE_BLOCKS_METADATA;
4758 
4759 		for (i = 0; i < count; i++) {
4760 			cond_resched();
4761 			if (is_metadata)
4762 				bh = sb_find_get_block(inode->i_sb, block + i);
4763 			ext4_forget(handle, is_metadata, inode, bh, block + i);
4764 		}
4765 	}
4766 
4767 do_more:
4768 	overflow = 0;
4769 	ext4_get_group_no_and_offset(sb, block, &block_group, &bit);
4770 
4771 	if (unlikely(EXT4_MB_GRP_BBITMAP_CORRUPT(
4772 			ext4_get_group_info(sb, block_group))))
4773 		return;
4774 
4775 	/*
4776 	 * Check to see if we are freeing blocks across a group
4777 	 * boundary.
4778 	 */
4779 	if (EXT4_C2B(sbi, bit) + count > EXT4_BLOCKS_PER_GROUP(sb)) {
4780 		overflow = EXT4_C2B(sbi, bit) + count -
4781 			EXT4_BLOCKS_PER_GROUP(sb);
4782 		count -= overflow;
4783 	}
4784 	count_clusters = EXT4_NUM_B2C(sbi, count);
4785 	bitmap_bh = ext4_read_block_bitmap(sb, block_group);
4786 	if (IS_ERR(bitmap_bh)) {
4787 		err = PTR_ERR(bitmap_bh);
4788 		bitmap_bh = NULL;
4789 		goto error_return;
4790 	}
4791 	gdp = ext4_get_group_desc(sb, block_group, &gd_bh);
4792 	if (!gdp) {
4793 		err = -EIO;
4794 		goto error_return;
4795 	}
4796 
4797 	if (in_range(ext4_block_bitmap(sb, gdp), block, count) ||
4798 	    in_range(ext4_inode_bitmap(sb, gdp), block, count) ||
4799 	    in_range(block, ext4_inode_table(sb, gdp),
4800 		     EXT4_SB(sb)->s_itb_per_group) ||
4801 	    in_range(block + count - 1, ext4_inode_table(sb, gdp),
4802 		     EXT4_SB(sb)->s_itb_per_group)) {
4803 
4804 		ext4_error(sb, "Freeing blocks in system zone - "
4805 			   "Block = %llu, count = %lu", block, count);
4806 		/* err = 0. ext4_std_error should be a no op */
4807 		goto error_return;
4808 	}
4809 
4810 	BUFFER_TRACE(bitmap_bh, "getting write access");
4811 	err = ext4_journal_get_write_access(handle, bitmap_bh);
4812 	if (err)
4813 		goto error_return;
4814 
4815 	/*
4816 	 * We are about to modify some metadata.  Call the journal APIs
4817 	 * to unshare ->b_data if a currently-committing transaction is
4818 	 * using it
4819 	 */
4820 	BUFFER_TRACE(gd_bh, "get_write_access");
4821 	err = ext4_journal_get_write_access(handle, gd_bh);
4822 	if (err)
4823 		goto error_return;
4824 #ifdef AGGRESSIVE_CHECK
4825 	{
4826 		int i;
4827 		for (i = 0; i < count_clusters; i++)
4828 			BUG_ON(!mb_test_bit(bit + i, bitmap_bh->b_data));
4829 	}
4830 #endif
4831 	trace_ext4_mballoc_free(sb, inode, block_group, bit, count_clusters);
4832 
4833 	/* __GFP_NOFAIL: retry infinitely, ignore TIF_MEMDIE and memcg limit. */
4834 	err = ext4_mb_load_buddy_gfp(sb, block_group, &e4b,
4835 				     GFP_NOFS|__GFP_NOFAIL);
4836 	if (err)
4837 		goto error_return;
4838 
4839 	/*
4840 	 * We need to make sure we don't reuse the freed block until after the
4841 	 * transaction is committed. We make an exception if the inode is to be
4842 	 * written in writeback mode since writeback mode has weak data
4843 	 * consistency guarantees.
4844 	 */
4845 	if (ext4_handle_valid(handle) &&
4846 	    ((flags & EXT4_FREE_BLOCKS_METADATA) ||
4847 	     !ext4_should_writeback_data(inode))) {
4848 		struct ext4_free_data *new_entry;
4849 		/*
4850 		 * We use __GFP_NOFAIL because ext4_free_blocks() is not allowed
4851 		 * to fail.
4852 		 */
4853 		new_entry = kmem_cache_alloc(ext4_free_data_cachep,
4854 				GFP_NOFS|__GFP_NOFAIL);
4855 		new_entry->efd_start_cluster = bit;
4856 		new_entry->efd_group = block_group;
4857 		new_entry->efd_count = count_clusters;
4858 		new_entry->efd_tid = handle->h_transaction->t_tid;
4859 
4860 		ext4_lock_group(sb, block_group);
4861 		mb_clear_bits(bitmap_bh->b_data, bit, count_clusters);
4862 		ext4_mb_free_metadata(handle, &e4b, new_entry);
4863 	} else {
4864 		/* need to update group_info->bb_free and bitmap
4865 		 * with group lock held. generate_buddy look at
4866 		 * them with group lock_held
4867 		 */
4868 		if (test_opt(sb, DISCARD)) {
4869 			err = ext4_issue_discard(sb, block_group, bit, count);
4870 			if (err && err != -EOPNOTSUPP)
4871 				ext4_msg(sb, KERN_WARNING, "discard request in"
4872 					 " group:%d block:%d count:%lu failed"
4873 					 " with %d", block_group, bit, count,
4874 					 err);
4875 		} else
4876 			EXT4_MB_GRP_CLEAR_TRIMMED(e4b.bd_info);
4877 
4878 		ext4_lock_group(sb, block_group);
4879 		mb_clear_bits(bitmap_bh->b_data, bit, count_clusters);
4880 		mb_free_blocks(inode, &e4b, bit, count_clusters);
4881 	}
4882 
4883 	ret = ext4_free_group_clusters(sb, gdp) + count_clusters;
4884 	ext4_free_group_clusters_set(sb, gdp, ret);
4885 	ext4_block_bitmap_csum_set(sb, block_group, gdp, bitmap_bh);
4886 	ext4_group_desc_csum_set(sb, block_group, gdp);
4887 	ext4_unlock_group(sb, block_group);
4888 
4889 	if (sbi->s_log_groups_per_flex) {
4890 		ext4_group_t flex_group = ext4_flex_group(sbi, block_group);
4891 		atomic64_add(count_clusters,
4892 			     &sbi->s_flex_groups[flex_group].free_clusters);
4893 	}
4894 
4895 	if (!(flags & EXT4_FREE_BLOCKS_NO_QUOT_UPDATE))
4896 		dquot_free_block(inode, EXT4_C2B(sbi, count_clusters));
4897 	percpu_counter_add(&sbi->s_freeclusters_counter, count_clusters);
4898 
4899 	ext4_mb_unload_buddy(&e4b);
4900 
4901 	/* We dirtied the bitmap block */
4902 	BUFFER_TRACE(bitmap_bh, "dirtied bitmap block");
4903 	err = ext4_handle_dirty_metadata(handle, NULL, bitmap_bh);
4904 
4905 	/* And the group descriptor block */
4906 	BUFFER_TRACE(gd_bh, "dirtied group descriptor block");
4907 	ret = ext4_handle_dirty_metadata(handle, NULL, gd_bh);
4908 	if (!err)
4909 		err = ret;
4910 
4911 	if (overflow && !err) {
4912 		block += count;
4913 		count = overflow;
4914 		put_bh(bitmap_bh);
4915 		goto do_more;
4916 	}
4917 error_return:
4918 	brelse(bitmap_bh);
4919 	ext4_std_error(sb, err);
4920 	return;
4921 }
4922 
4923 /**
4924  * ext4_group_add_blocks() -- Add given blocks to an existing group
4925  * @handle:			handle to this transaction
4926  * @sb:				super block
4927  * @block:			start physical block to add to the block group
4928  * @count:			number of blocks to free
4929  *
4930  * This marks the blocks as free in the bitmap and buddy.
4931  */
4932 int ext4_group_add_blocks(handle_t *handle, struct super_block *sb,
4933 			 ext4_fsblk_t block, unsigned long count)
4934 {
4935 	struct buffer_head *bitmap_bh = NULL;
4936 	struct buffer_head *gd_bh;
4937 	ext4_group_t block_group;
4938 	ext4_grpblk_t bit;
4939 	unsigned int i;
4940 	struct ext4_group_desc *desc;
4941 	struct ext4_sb_info *sbi = EXT4_SB(sb);
4942 	struct ext4_buddy e4b;
4943 	int err = 0, ret, blk_free_count;
4944 	ext4_grpblk_t blocks_freed;
4945 
4946 	ext4_debug("Adding block(s) %llu-%llu\n", block, block + count - 1);
4947 
4948 	if (count == 0)
4949 		return 0;
4950 
4951 	ext4_get_group_no_and_offset(sb, block, &block_group, &bit);
4952 	/*
4953 	 * Check to see if we are freeing blocks across a group
4954 	 * boundary.
4955 	 */
4956 	if (bit + count > EXT4_BLOCKS_PER_GROUP(sb)) {
4957 		ext4_warning(sb, "too much blocks added to group %u",
4958 			     block_group);
4959 		err = -EINVAL;
4960 		goto error_return;
4961 	}
4962 
4963 	bitmap_bh = ext4_read_block_bitmap(sb, block_group);
4964 	if (IS_ERR(bitmap_bh)) {
4965 		err = PTR_ERR(bitmap_bh);
4966 		bitmap_bh = NULL;
4967 		goto error_return;
4968 	}
4969 
4970 	desc = ext4_get_group_desc(sb, block_group, &gd_bh);
4971 	if (!desc) {
4972 		err = -EIO;
4973 		goto error_return;
4974 	}
4975 
4976 	if (in_range(ext4_block_bitmap(sb, desc), block, count) ||
4977 	    in_range(ext4_inode_bitmap(sb, desc), block, count) ||
4978 	    in_range(block, ext4_inode_table(sb, desc), sbi->s_itb_per_group) ||
4979 	    in_range(block + count - 1, ext4_inode_table(sb, desc),
4980 		     sbi->s_itb_per_group)) {
4981 		ext4_error(sb, "Adding blocks in system zones - "
4982 			   "Block = %llu, count = %lu",
4983 			   block, count);
4984 		err = -EINVAL;
4985 		goto error_return;
4986 	}
4987 
4988 	BUFFER_TRACE(bitmap_bh, "getting write access");
4989 	err = ext4_journal_get_write_access(handle, bitmap_bh);
4990 	if (err)
4991 		goto error_return;
4992 
4993 	/*
4994 	 * We are about to modify some metadata.  Call the journal APIs
4995 	 * to unshare ->b_data if a currently-committing transaction is
4996 	 * using it
4997 	 */
4998 	BUFFER_TRACE(gd_bh, "get_write_access");
4999 	err = ext4_journal_get_write_access(handle, gd_bh);
5000 	if (err)
5001 		goto error_return;
5002 
5003 	for (i = 0, blocks_freed = 0; i < count; i++) {
5004 		BUFFER_TRACE(bitmap_bh, "clear bit");
5005 		if (!mb_test_bit(bit + i, bitmap_bh->b_data)) {
5006 			ext4_error(sb, "bit already cleared for block %llu",
5007 				   (ext4_fsblk_t)(block + i));
5008 			BUFFER_TRACE(bitmap_bh, "bit already cleared");
5009 		} else {
5010 			blocks_freed++;
5011 		}
5012 	}
5013 
5014 	err = ext4_mb_load_buddy(sb, block_group, &e4b);
5015 	if (err)
5016 		goto error_return;
5017 
5018 	/*
5019 	 * need to update group_info->bb_free and bitmap
5020 	 * with group lock held. generate_buddy look at
5021 	 * them with group lock_held
5022 	 */
5023 	ext4_lock_group(sb, block_group);
5024 	mb_clear_bits(bitmap_bh->b_data, bit, count);
5025 	mb_free_blocks(NULL, &e4b, bit, count);
5026 	blk_free_count = blocks_freed + ext4_free_group_clusters(sb, desc);
5027 	ext4_free_group_clusters_set(sb, desc, blk_free_count);
5028 	ext4_block_bitmap_csum_set(sb, block_group, desc, bitmap_bh);
5029 	ext4_group_desc_csum_set(sb, block_group, desc);
5030 	ext4_unlock_group(sb, block_group);
5031 	percpu_counter_add(&sbi->s_freeclusters_counter,
5032 			   EXT4_NUM_B2C(sbi, blocks_freed));
5033 
5034 	if (sbi->s_log_groups_per_flex) {
5035 		ext4_group_t flex_group = ext4_flex_group(sbi, block_group);
5036 		atomic64_add(EXT4_NUM_B2C(sbi, blocks_freed),
5037 			     &sbi->s_flex_groups[flex_group].free_clusters);
5038 	}
5039 
5040 	ext4_mb_unload_buddy(&e4b);
5041 
5042 	/* We dirtied the bitmap block */
5043 	BUFFER_TRACE(bitmap_bh, "dirtied bitmap block");
5044 	err = ext4_handle_dirty_metadata(handle, NULL, bitmap_bh);
5045 
5046 	/* And the group descriptor block */
5047 	BUFFER_TRACE(gd_bh, "dirtied group descriptor block");
5048 	ret = ext4_handle_dirty_metadata(handle, NULL, gd_bh);
5049 	if (!err)
5050 		err = ret;
5051 
5052 error_return:
5053 	brelse(bitmap_bh);
5054 	ext4_std_error(sb, err);
5055 	return err;
5056 }
5057 
5058 /**
5059  * ext4_trim_extent -- function to TRIM one single free extent in the group
5060  * @sb:		super block for the file system
5061  * @start:	starting block of the free extent in the alloc. group
5062  * @count:	number of blocks to TRIM
5063  * @group:	alloc. group we are working with
5064  * @e4b:	ext4 buddy for the group
5065  *
5066  * Trim "count" blocks starting at "start" in the "group". To assure that no
5067  * one will allocate those blocks, mark it as used in buddy bitmap. This must
5068  * be called with under the group lock.
5069  */
5070 static int ext4_trim_extent(struct super_block *sb, int start, int count,
5071 			     ext4_group_t group, struct ext4_buddy *e4b)
5072 __releases(bitlock)
5073 __acquires(bitlock)
5074 {
5075 	struct ext4_free_extent ex;
5076 	int ret = 0;
5077 
5078 	trace_ext4_trim_extent(sb, group, start, count);
5079 
5080 	assert_spin_locked(ext4_group_lock_ptr(sb, group));
5081 
5082 	ex.fe_start = start;
5083 	ex.fe_group = group;
5084 	ex.fe_len = count;
5085 
5086 	/*
5087 	 * Mark blocks used, so no one can reuse them while
5088 	 * being trimmed.
5089 	 */
5090 	mb_mark_used(e4b, &ex);
5091 	ext4_unlock_group(sb, group);
5092 	ret = ext4_issue_discard(sb, group, start, count);
5093 	ext4_lock_group(sb, group);
5094 	mb_free_blocks(NULL, e4b, start, ex.fe_len);
5095 	return ret;
5096 }
5097 
5098 /**
5099  * ext4_trim_all_free -- function to trim all free space in alloc. group
5100  * @sb:			super block for file system
5101  * @group:		group to be trimmed
5102  * @start:		first group block to examine
5103  * @max:		last group block to examine
5104  * @minblocks:		minimum extent block count
5105  *
5106  * ext4_trim_all_free walks through group's buddy bitmap searching for free
5107  * extents. When the free block is found, ext4_trim_extent is called to TRIM
5108  * the extent.
5109  *
5110  *
5111  * ext4_trim_all_free walks through group's block bitmap searching for free
5112  * extents. When the free extent is found, mark it as used in group buddy
5113  * bitmap. Then issue a TRIM command on this extent and free the extent in
5114  * the group buddy bitmap. This is done until whole group is scanned.
5115  */
5116 static ext4_grpblk_t
5117 ext4_trim_all_free(struct super_block *sb, ext4_group_t group,
5118 		   ext4_grpblk_t start, ext4_grpblk_t max,
5119 		   ext4_grpblk_t minblocks)
5120 {
5121 	void *bitmap;
5122 	ext4_grpblk_t next, count = 0, free_count = 0;
5123 	struct ext4_buddy e4b;
5124 	int ret = 0;
5125 
5126 	trace_ext4_trim_all_free(sb, group, start, max);
5127 
5128 	ret = ext4_mb_load_buddy(sb, group, &e4b);
5129 	if (ret) {
5130 		ext4_error(sb, "Error in loading buddy "
5131 				"information for %u", group);
5132 		return ret;
5133 	}
5134 	bitmap = e4b.bd_bitmap;
5135 
5136 	ext4_lock_group(sb, group);
5137 	if (EXT4_MB_GRP_WAS_TRIMMED(e4b.bd_info) &&
5138 	    minblocks >= atomic_read(&EXT4_SB(sb)->s_last_trim_minblks))
5139 		goto out;
5140 
5141 	start = (e4b.bd_info->bb_first_free > start) ?
5142 		e4b.bd_info->bb_first_free : start;
5143 
5144 	while (start <= max) {
5145 		start = mb_find_next_zero_bit(bitmap, max + 1, start);
5146 		if (start > max)
5147 			break;
5148 		next = mb_find_next_bit(bitmap, max + 1, start);
5149 
5150 		if ((next - start) >= minblocks) {
5151 			ret = ext4_trim_extent(sb, start,
5152 					       next - start, group, &e4b);
5153 			if (ret && ret != -EOPNOTSUPP)
5154 				break;
5155 			ret = 0;
5156 			count += next - start;
5157 		}
5158 		free_count += next - start;
5159 		start = next + 1;
5160 
5161 		if (fatal_signal_pending(current)) {
5162 			count = -ERESTARTSYS;
5163 			break;
5164 		}
5165 
5166 		if (need_resched()) {
5167 			ext4_unlock_group(sb, group);
5168 			cond_resched();
5169 			ext4_lock_group(sb, group);
5170 		}
5171 
5172 		if ((e4b.bd_info->bb_free - free_count) < minblocks)
5173 			break;
5174 	}
5175 
5176 	if (!ret) {
5177 		ret = count;
5178 		EXT4_MB_GRP_SET_TRIMMED(e4b.bd_info);
5179 	}
5180 out:
5181 	ext4_unlock_group(sb, group);
5182 	ext4_mb_unload_buddy(&e4b);
5183 
5184 	ext4_debug("trimmed %d blocks in the group %d\n",
5185 		count, group);
5186 
5187 	return ret;
5188 }
5189 
5190 /**
5191  * ext4_trim_fs() -- trim ioctl handle function
5192  * @sb:			superblock for filesystem
5193  * @range:		fstrim_range structure
5194  *
5195  * start:	First Byte to trim
5196  * len:		number of Bytes to trim from start
5197  * minlen:	minimum extent length in Bytes
5198  * ext4_trim_fs goes through all allocation groups containing Bytes from
5199  * start to start+len. For each such a group ext4_trim_all_free function
5200  * is invoked to trim all free space.
5201  */
5202 int ext4_trim_fs(struct super_block *sb, struct fstrim_range *range)
5203 {
5204 	struct ext4_group_info *grp;
5205 	ext4_group_t group, first_group, last_group;
5206 	ext4_grpblk_t cnt = 0, first_cluster, last_cluster;
5207 	uint64_t start, end, minlen, trimmed = 0;
5208 	ext4_fsblk_t first_data_blk =
5209 			le32_to_cpu(EXT4_SB(sb)->s_es->s_first_data_block);
5210 	ext4_fsblk_t max_blks = ext4_blocks_count(EXT4_SB(sb)->s_es);
5211 	int ret = 0;
5212 
5213 	start = range->start >> sb->s_blocksize_bits;
5214 	end = start + (range->len >> sb->s_blocksize_bits) - 1;
5215 	minlen = EXT4_NUM_B2C(EXT4_SB(sb),
5216 			      range->minlen >> sb->s_blocksize_bits);
5217 
5218 	if (minlen > EXT4_CLUSTERS_PER_GROUP(sb) ||
5219 	    start >= max_blks ||
5220 	    range->len < sb->s_blocksize)
5221 		return -EINVAL;
5222 	if (end >= max_blks)
5223 		end = max_blks - 1;
5224 	if (end <= first_data_blk)
5225 		goto out;
5226 	if (start < first_data_blk)
5227 		start = first_data_blk;
5228 
5229 	/* Determine first and last group to examine based on start and end */
5230 	ext4_get_group_no_and_offset(sb, (ext4_fsblk_t) start,
5231 				     &first_group, &first_cluster);
5232 	ext4_get_group_no_and_offset(sb, (ext4_fsblk_t) end,
5233 				     &last_group, &last_cluster);
5234 
5235 	/* end now represents the last cluster to discard in this group */
5236 	end = EXT4_CLUSTERS_PER_GROUP(sb) - 1;
5237 
5238 	for (group = first_group; group <= last_group; group++) {
5239 		grp = ext4_get_group_info(sb, group);
5240 		/* We only do this if the grp has never been initialized */
5241 		if (unlikely(EXT4_MB_GRP_NEED_INIT(grp))) {
5242 			ret = ext4_mb_init_group(sb, group, GFP_NOFS);
5243 			if (ret)
5244 				break;
5245 		}
5246 
5247 		/*
5248 		 * For all the groups except the last one, last cluster will
5249 		 * always be EXT4_CLUSTERS_PER_GROUP(sb)-1, so we only need to
5250 		 * change it for the last group, note that last_cluster is
5251 		 * already computed earlier by ext4_get_group_no_and_offset()
5252 		 */
5253 		if (group == last_group)
5254 			end = last_cluster;
5255 
5256 		if (grp->bb_free >= minlen) {
5257 			cnt = ext4_trim_all_free(sb, group, first_cluster,
5258 						end, minlen);
5259 			if (cnt < 0) {
5260 				ret = cnt;
5261 				break;
5262 			}
5263 			trimmed += cnt;
5264 		}
5265 
5266 		/*
5267 		 * For every group except the first one, we are sure
5268 		 * that the first cluster to discard will be cluster #0.
5269 		 */
5270 		first_cluster = 0;
5271 	}
5272 
5273 	if (!ret)
5274 		atomic_set(&EXT4_SB(sb)->s_last_trim_minblks, minlen);
5275 
5276 out:
5277 	range->len = EXT4_C2B(EXT4_SB(sb), trimmed) << sb->s_blocksize_bits;
5278 	return ret;
5279 }
5280 
5281 /* Iterate all the free extents in the group. */
5282 int
5283 ext4_mballoc_query_range(
5284 	struct super_block		*sb,
5285 	ext4_group_t			group,
5286 	ext4_grpblk_t			start,
5287 	ext4_grpblk_t			end,
5288 	ext4_mballoc_query_range_fn	formatter,
5289 	void				*priv)
5290 {
5291 	void				*bitmap;
5292 	ext4_grpblk_t			next;
5293 	struct ext4_buddy		e4b;
5294 	int				error;
5295 
5296 	error = ext4_mb_load_buddy(sb, group, &e4b);
5297 	if (error)
5298 		return error;
5299 	bitmap = e4b.bd_bitmap;
5300 
5301 	ext4_lock_group(sb, group);
5302 
5303 	start = (e4b.bd_info->bb_first_free > start) ?
5304 		e4b.bd_info->bb_first_free : start;
5305 	if (end >= EXT4_CLUSTERS_PER_GROUP(sb))
5306 		end = EXT4_CLUSTERS_PER_GROUP(sb) - 1;
5307 
5308 	while (start <= end) {
5309 		start = mb_find_next_zero_bit(bitmap, end + 1, start);
5310 		if (start > end)
5311 			break;
5312 		next = mb_find_next_bit(bitmap, end + 1, start);
5313 
5314 		ext4_unlock_group(sb, group);
5315 		error = formatter(sb, group, start, next - start, priv);
5316 		if (error)
5317 			goto out_unload;
5318 		ext4_lock_group(sb, group);
5319 
5320 		start = next + 1;
5321 	}
5322 
5323 	ext4_unlock_group(sb, group);
5324 out_unload:
5325 	ext4_mb_unload_buddy(&e4b);
5326 
5327 	return error;
5328 }
5329