xref: /openbmc/linux/fs/ext4/extents.c (revision 7877191c28b1e140795c0c951dde8aad43757378)
1 /*
2  * Copyright (c) 2003-2006, Cluster File Systems, Inc, info@clusterfs.com
3  * Written by Alex Tomas <alex@clusterfs.com>
4  *
5  * Architecture independence:
6  *   Copyright (c) 2005, Bull S.A.
7  *   Written by Pierre Peiffer <pierre.peiffer@bull.net>
8  *
9  * This program is free software; you can redistribute it and/or modify
10  * it under the terms of the GNU General Public License version 2 as
11  * published by the Free Software Foundation.
12  *
13  * This program is distributed in the hope that it will be useful,
14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
16  * GNU General Public License for more details.
17  *
18  * You should have received a copy of the GNU General Public Licens
19  * along with this program; if not, write to the Free Software
20  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-
21  */
22 
23 /*
24  * Extents support for EXT4
25  *
26  * TODO:
27  *   - ext4*_error() should be used in some situations
28  *   - analyze all BUG()/BUG_ON(), use -EIO where appropriate
29  *   - smart tree reduction
30  */
31 
32 #include <linux/fs.h>
33 #include <linux/time.h>
34 #include <linux/jbd2.h>
35 #include <linux/highuid.h>
36 #include <linux/pagemap.h>
37 #include <linux/quotaops.h>
38 #include <linux/string.h>
39 #include <linux/slab.h>
40 #include <linux/falloc.h>
41 #include <asm/uaccess.h>
42 #include <linux/fiemap.h>
43 #include "ext4_jbd2.h"
44 
45 #include <trace/events/ext4.h>
46 
47 /*
48  * used by extent splitting.
49  */
50 #define EXT4_EXT_MAY_ZEROOUT	0x1  /* safe to zeroout if split fails \
51 					due to ENOSPC */
52 #define EXT4_EXT_MARK_UNINIT1	0x2  /* mark first half uninitialized */
53 #define EXT4_EXT_MARK_UNINIT2	0x4  /* mark second half uninitialized */
54 
55 static int ext4_split_extent(handle_t *handle,
56 				struct inode *inode,
57 				struct ext4_ext_path *path,
58 				struct ext4_map_blocks *map,
59 				int split_flag,
60 				int flags);
61 
62 static int ext4_split_extent_at(handle_t *handle,
63 			     struct inode *inode,
64 			     struct ext4_ext_path *path,
65 			     ext4_lblk_t split,
66 			     int split_flag,
67 			     int flags);
68 
69 static int ext4_ext_truncate_extend_restart(handle_t *handle,
70 					    struct inode *inode,
71 					    int needed)
72 {
73 	int err;
74 
75 	if (!ext4_handle_valid(handle))
76 		return 0;
77 	if (handle->h_buffer_credits > needed)
78 		return 0;
79 	err = ext4_journal_extend(handle, needed);
80 	if (err <= 0)
81 		return err;
82 	err = ext4_truncate_restart_trans(handle, inode, needed);
83 	if (err == 0)
84 		err = -EAGAIN;
85 
86 	return err;
87 }
88 
89 /*
90  * could return:
91  *  - EROFS
92  *  - ENOMEM
93  */
94 static int ext4_ext_get_access(handle_t *handle, struct inode *inode,
95 				struct ext4_ext_path *path)
96 {
97 	if (path->p_bh) {
98 		/* path points to block */
99 		return ext4_journal_get_write_access(handle, path->p_bh);
100 	}
101 	/* path points to leaf/index in inode body */
102 	/* we use in-core data, no need to protect them */
103 	return 0;
104 }
105 
106 /*
107  * could return:
108  *  - EROFS
109  *  - ENOMEM
110  *  - EIO
111  */
112 #define ext4_ext_dirty(handle, inode, path) \
113 		__ext4_ext_dirty(__func__, __LINE__, (handle), (inode), (path))
114 static int __ext4_ext_dirty(const char *where, unsigned int line,
115 			    handle_t *handle, struct inode *inode,
116 			    struct ext4_ext_path *path)
117 {
118 	int err;
119 	if (path->p_bh) {
120 		/* path points to block */
121 		err = __ext4_handle_dirty_metadata(where, line, handle,
122 						   inode, path->p_bh);
123 	} else {
124 		/* path points to leaf/index in inode body */
125 		err = ext4_mark_inode_dirty(handle, inode);
126 	}
127 	return err;
128 }
129 
130 static ext4_fsblk_t ext4_ext_find_goal(struct inode *inode,
131 			      struct ext4_ext_path *path,
132 			      ext4_lblk_t block)
133 {
134 	if (path) {
135 		int depth = path->p_depth;
136 		struct ext4_extent *ex;
137 
138 		/*
139 		 * Try to predict block placement assuming that we are
140 		 * filling in a file which will eventually be
141 		 * non-sparse --- i.e., in the case of libbfd writing
142 		 * an ELF object sections out-of-order but in a way
143 		 * the eventually results in a contiguous object or
144 		 * executable file, or some database extending a table
145 		 * space file.  However, this is actually somewhat
146 		 * non-ideal if we are writing a sparse file such as
147 		 * qemu or KVM writing a raw image file that is going
148 		 * to stay fairly sparse, since it will end up
149 		 * fragmenting the file system's free space.  Maybe we
150 		 * should have some hueristics or some way to allow
151 		 * userspace to pass a hint to file system,
152 		 * especially if the latter case turns out to be
153 		 * common.
154 		 */
155 		ex = path[depth].p_ext;
156 		if (ex) {
157 			ext4_fsblk_t ext_pblk = ext4_ext_pblock(ex);
158 			ext4_lblk_t ext_block = le32_to_cpu(ex->ee_block);
159 
160 			if (block > ext_block)
161 				return ext_pblk + (block - ext_block);
162 			else
163 				return ext_pblk - (ext_block - block);
164 		}
165 
166 		/* it looks like index is empty;
167 		 * try to find starting block from index itself */
168 		if (path[depth].p_bh)
169 			return path[depth].p_bh->b_blocknr;
170 	}
171 
172 	/* OK. use inode's group */
173 	return ext4_inode_to_goal_block(inode);
174 }
175 
176 /*
177  * Allocation for a meta data block
178  */
179 static ext4_fsblk_t
180 ext4_ext_new_meta_block(handle_t *handle, struct inode *inode,
181 			struct ext4_ext_path *path,
182 			struct ext4_extent *ex, int *err, unsigned int flags)
183 {
184 	ext4_fsblk_t goal, newblock;
185 
186 	goal = ext4_ext_find_goal(inode, path, le32_to_cpu(ex->ee_block));
187 	newblock = ext4_new_meta_blocks(handle, inode, goal, flags,
188 					NULL, err);
189 	return newblock;
190 }
191 
192 static inline int ext4_ext_space_block(struct inode *inode, int check)
193 {
194 	int size;
195 
196 	size = (inode->i_sb->s_blocksize - sizeof(struct ext4_extent_header))
197 			/ sizeof(struct ext4_extent);
198 #ifdef AGGRESSIVE_TEST
199 	if (!check && size > 6)
200 		size = 6;
201 #endif
202 	return size;
203 }
204 
205 static inline int ext4_ext_space_block_idx(struct inode *inode, int check)
206 {
207 	int size;
208 
209 	size = (inode->i_sb->s_blocksize - sizeof(struct ext4_extent_header))
210 			/ sizeof(struct ext4_extent_idx);
211 #ifdef AGGRESSIVE_TEST
212 	if (!check && size > 5)
213 		size = 5;
214 #endif
215 	return size;
216 }
217 
218 static inline int ext4_ext_space_root(struct inode *inode, int check)
219 {
220 	int size;
221 
222 	size = sizeof(EXT4_I(inode)->i_data);
223 	size -= sizeof(struct ext4_extent_header);
224 	size /= sizeof(struct ext4_extent);
225 #ifdef AGGRESSIVE_TEST
226 	if (!check && size > 3)
227 		size = 3;
228 #endif
229 	return size;
230 }
231 
232 static inline int ext4_ext_space_root_idx(struct inode *inode, int check)
233 {
234 	int size;
235 
236 	size = sizeof(EXT4_I(inode)->i_data);
237 	size -= sizeof(struct ext4_extent_header);
238 	size /= sizeof(struct ext4_extent_idx);
239 #ifdef AGGRESSIVE_TEST
240 	if (!check && size > 4)
241 		size = 4;
242 #endif
243 	return size;
244 }
245 
246 /*
247  * Calculate the number of metadata blocks needed
248  * to allocate @blocks
249  * Worse case is one block per extent
250  */
251 int ext4_ext_calc_metadata_amount(struct inode *inode, ext4_lblk_t lblock)
252 {
253 	struct ext4_inode_info *ei = EXT4_I(inode);
254 	int idxs;
255 
256 	idxs = ((inode->i_sb->s_blocksize - sizeof(struct ext4_extent_header))
257 		/ sizeof(struct ext4_extent_idx));
258 
259 	/*
260 	 * If the new delayed allocation block is contiguous with the
261 	 * previous da block, it can share index blocks with the
262 	 * previous block, so we only need to allocate a new index
263 	 * block every idxs leaf blocks.  At ldxs**2 blocks, we need
264 	 * an additional index block, and at ldxs**3 blocks, yet
265 	 * another index blocks.
266 	 */
267 	if (ei->i_da_metadata_calc_len &&
268 	    ei->i_da_metadata_calc_last_lblock+1 == lblock) {
269 		int num = 0;
270 
271 		if ((ei->i_da_metadata_calc_len % idxs) == 0)
272 			num++;
273 		if ((ei->i_da_metadata_calc_len % (idxs*idxs)) == 0)
274 			num++;
275 		if ((ei->i_da_metadata_calc_len % (idxs*idxs*idxs)) == 0) {
276 			num++;
277 			ei->i_da_metadata_calc_len = 0;
278 		} else
279 			ei->i_da_metadata_calc_len++;
280 		ei->i_da_metadata_calc_last_lblock++;
281 		return num;
282 	}
283 
284 	/*
285 	 * In the worst case we need a new set of index blocks at
286 	 * every level of the inode's extent tree.
287 	 */
288 	ei->i_da_metadata_calc_len = 1;
289 	ei->i_da_metadata_calc_last_lblock = lblock;
290 	return ext_depth(inode) + 1;
291 }
292 
293 static int
294 ext4_ext_max_entries(struct inode *inode, int depth)
295 {
296 	int max;
297 
298 	if (depth == ext_depth(inode)) {
299 		if (depth == 0)
300 			max = ext4_ext_space_root(inode, 1);
301 		else
302 			max = ext4_ext_space_root_idx(inode, 1);
303 	} else {
304 		if (depth == 0)
305 			max = ext4_ext_space_block(inode, 1);
306 		else
307 			max = ext4_ext_space_block_idx(inode, 1);
308 	}
309 
310 	return max;
311 }
312 
313 static int ext4_valid_extent(struct inode *inode, struct ext4_extent *ext)
314 {
315 	ext4_fsblk_t block = ext4_ext_pblock(ext);
316 	int len = ext4_ext_get_actual_len(ext);
317 
318 	if (len == 0)
319 		return 0;
320 	return ext4_data_block_valid(EXT4_SB(inode->i_sb), block, len);
321 }
322 
323 static int ext4_valid_extent_idx(struct inode *inode,
324 				struct ext4_extent_idx *ext_idx)
325 {
326 	ext4_fsblk_t block = ext4_idx_pblock(ext_idx);
327 
328 	return ext4_data_block_valid(EXT4_SB(inode->i_sb), block, 1);
329 }
330 
331 static int ext4_valid_extent_entries(struct inode *inode,
332 				struct ext4_extent_header *eh,
333 				int depth)
334 {
335 	unsigned short entries;
336 	if (eh->eh_entries == 0)
337 		return 1;
338 
339 	entries = le16_to_cpu(eh->eh_entries);
340 
341 	if (depth == 0) {
342 		/* leaf entries */
343 		struct ext4_extent *ext = EXT_FIRST_EXTENT(eh);
344 		while (entries) {
345 			if (!ext4_valid_extent(inode, ext))
346 				return 0;
347 			ext++;
348 			entries--;
349 		}
350 	} else {
351 		struct ext4_extent_idx *ext_idx = EXT_FIRST_INDEX(eh);
352 		while (entries) {
353 			if (!ext4_valid_extent_idx(inode, ext_idx))
354 				return 0;
355 			ext_idx++;
356 			entries--;
357 		}
358 	}
359 	return 1;
360 }
361 
362 static int __ext4_ext_check(const char *function, unsigned int line,
363 			    struct inode *inode, struct ext4_extent_header *eh,
364 			    int depth)
365 {
366 	const char *error_msg;
367 	int max = 0;
368 
369 	if (unlikely(eh->eh_magic != EXT4_EXT_MAGIC)) {
370 		error_msg = "invalid magic";
371 		goto corrupted;
372 	}
373 	if (unlikely(le16_to_cpu(eh->eh_depth) != depth)) {
374 		error_msg = "unexpected eh_depth";
375 		goto corrupted;
376 	}
377 	if (unlikely(eh->eh_max == 0)) {
378 		error_msg = "invalid eh_max";
379 		goto corrupted;
380 	}
381 	max = ext4_ext_max_entries(inode, depth);
382 	if (unlikely(le16_to_cpu(eh->eh_max) > max)) {
383 		error_msg = "too large eh_max";
384 		goto corrupted;
385 	}
386 	if (unlikely(le16_to_cpu(eh->eh_entries) > le16_to_cpu(eh->eh_max))) {
387 		error_msg = "invalid eh_entries";
388 		goto corrupted;
389 	}
390 	if (!ext4_valid_extent_entries(inode, eh, depth)) {
391 		error_msg = "invalid extent entries";
392 		goto corrupted;
393 	}
394 	return 0;
395 
396 corrupted:
397 	ext4_error_inode(inode, function, line, 0,
398 			"bad header/extent: %s - magic %x, "
399 			"entries %u, max %u(%u), depth %u(%u)",
400 			error_msg, le16_to_cpu(eh->eh_magic),
401 			le16_to_cpu(eh->eh_entries), le16_to_cpu(eh->eh_max),
402 			max, le16_to_cpu(eh->eh_depth), depth);
403 
404 	return -EIO;
405 }
406 
407 #define ext4_ext_check(inode, eh, depth)	\
408 	__ext4_ext_check(__func__, __LINE__, inode, eh, depth)
409 
410 int ext4_ext_check_inode(struct inode *inode)
411 {
412 	return ext4_ext_check(inode, ext_inode_hdr(inode), ext_depth(inode));
413 }
414 
415 #ifdef EXT_DEBUG
416 static void ext4_ext_show_path(struct inode *inode, struct ext4_ext_path *path)
417 {
418 	int k, l = path->p_depth;
419 
420 	ext_debug("path:");
421 	for (k = 0; k <= l; k++, path++) {
422 		if (path->p_idx) {
423 		  ext_debug("  %d->%llu", le32_to_cpu(path->p_idx->ei_block),
424 			    ext4_idx_pblock(path->p_idx));
425 		} else if (path->p_ext) {
426 			ext_debug("  %d:[%d]%d:%llu ",
427 				  le32_to_cpu(path->p_ext->ee_block),
428 				  ext4_ext_is_uninitialized(path->p_ext),
429 				  ext4_ext_get_actual_len(path->p_ext),
430 				  ext4_ext_pblock(path->p_ext));
431 		} else
432 			ext_debug("  []");
433 	}
434 	ext_debug("\n");
435 }
436 
437 static void ext4_ext_show_leaf(struct inode *inode, struct ext4_ext_path *path)
438 {
439 	int depth = ext_depth(inode);
440 	struct ext4_extent_header *eh;
441 	struct ext4_extent *ex;
442 	int i;
443 
444 	if (!path)
445 		return;
446 
447 	eh = path[depth].p_hdr;
448 	ex = EXT_FIRST_EXTENT(eh);
449 
450 	ext_debug("Displaying leaf extents for inode %lu\n", inode->i_ino);
451 
452 	for (i = 0; i < le16_to_cpu(eh->eh_entries); i++, ex++) {
453 		ext_debug("%d:[%d]%d:%llu ", le32_to_cpu(ex->ee_block),
454 			  ext4_ext_is_uninitialized(ex),
455 			  ext4_ext_get_actual_len(ex), ext4_ext_pblock(ex));
456 	}
457 	ext_debug("\n");
458 }
459 
460 static void ext4_ext_show_move(struct inode *inode, struct ext4_ext_path *path,
461 			ext4_fsblk_t newblock, int level)
462 {
463 	int depth = ext_depth(inode);
464 	struct ext4_extent *ex;
465 
466 	if (depth != level) {
467 		struct ext4_extent_idx *idx;
468 		idx = path[level].p_idx;
469 		while (idx <= EXT_MAX_INDEX(path[level].p_hdr)) {
470 			ext_debug("%d: move %d:%llu in new index %llu\n", level,
471 					le32_to_cpu(idx->ei_block),
472 					ext4_idx_pblock(idx),
473 					newblock);
474 			idx++;
475 		}
476 
477 		return;
478 	}
479 
480 	ex = path[depth].p_ext;
481 	while (ex <= EXT_MAX_EXTENT(path[depth].p_hdr)) {
482 		ext_debug("move %d:%llu:[%d]%d in new leaf %llu\n",
483 				le32_to_cpu(ex->ee_block),
484 				ext4_ext_pblock(ex),
485 				ext4_ext_is_uninitialized(ex),
486 				ext4_ext_get_actual_len(ex),
487 				newblock);
488 		ex++;
489 	}
490 }
491 
492 #else
493 #define ext4_ext_show_path(inode, path)
494 #define ext4_ext_show_leaf(inode, path)
495 #define ext4_ext_show_move(inode, path, newblock, level)
496 #endif
497 
498 void ext4_ext_drop_refs(struct ext4_ext_path *path)
499 {
500 	int depth = path->p_depth;
501 	int i;
502 
503 	for (i = 0; i <= depth; i++, path++)
504 		if (path->p_bh) {
505 			brelse(path->p_bh);
506 			path->p_bh = NULL;
507 		}
508 }
509 
510 /*
511  * ext4_ext_binsearch_idx:
512  * binary search for the closest index of the given block
513  * the header must be checked before calling this
514  */
515 static void
516 ext4_ext_binsearch_idx(struct inode *inode,
517 			struct ext4_ext_path *path, ext4_lblk_t block)
518 {
519 	struct ext4_extent_header *eh = path->p_hdr;
520 	struct ext4_extent_idx *r, *l, *m;
521 
522 
523 	ext_debug("binsearch for %u(idx):  ", block);
524 
525 	l = EXT_FIRST_INDEX(eh) + 1;
526 	r = EXT_LAST_INDEX(eh);
527 	while (l <= r) {
528 		m = l + (r - l) / 2;
529 		if (block < le32_to_cpu(m->ei_block))
530 			r = m - 1;
531 		else
532 			l = m + 1;
533 		ext_debug("%p(%u):%p(%u):%p(%u) ", l, le32_to_cpu(l->ei_block),
534 				m, le32_to_cpu(m->ei_block),
535 				r, le32_to_cpu(r->ei_block));
536 	}
537 
538 	path->p_idx = l - 1;
539 	ext_debug("  -> %d->%lld ", le32_to_cpu(path->p_idx->ei_block),
540 		  ext4_idx_pblock(path->p_idx));
541 
542 #ifdef CHECK_BINSEARCH
543 	{
544 		struct ext4_extent_idx *chix, *ix;
545 		int k;
546 
547 		chix = ix = EXT_FIRST_INDEX(eh);
548 		for (k = 0; k < le16_to_cpu(eh->eh_entries); k++, ix++) {
549 		  if (k != 0 &&
550 		      le32_to_cpu(ix->ei_block) <= le32_to_cpu(ix[-1].ei_block)) {
551 				printk(KERN_DEBUG "k=%d, ix=0x%p, "
552 				       "first=0x%p\n", k,
553 				       ix, EXT_FIRST_INDEX(eh));
554 				printk(KERN_DEBUG "%u <= %u\n",
555 				       le32_to_cpu(ix->ei_block),
556 				       le32_to_cpu(ix[-1].ei_block));
557 			}
558 			BUG_ON(k && le32_to_cpu(ix->ei_block)
559 					   <= le32_to_cpu(ix[-1].ei_block));
560 			if (block < le32_to_cpu(ix->ei_block))
561 				break;
562 			chix = ix;
563 		}
564 		BUG_ON(chix != path->p_idx);
565 	}
566 #endif
567 
568 }
569 
570 /*
571  * ext4_ext_binsearch:
572  * binary search for closest extent of the given block
573  * the header must be checked before calling this
574  */
575 static void
576 ext4_ext_binsearch(struct inode *inode,
577 		struct ext4_ext_path *path, ext4_lblk_t block)
578 {
579 	struct ext4_extent_header *eh = path->p_hdr;
580 	struct ext4_extent *r, *l, *m;
581 
582 	if (eh->eh_entries == 0) {
583 		/*
584 		 * this leaf is empty:
585 		 * we get such a leaf in split/add case
586 		 */
587 		return;
588 	}
589 
590 	ext_debug("binsearch for %u:  ", block);
591 
592 	l = EXT_FIRST_EXTENT(eh) + 1;
593 	r = EXT_LAST_EXTENT(eh);
594 
595 	while (l <= r) {
596 		m = l + (r - l) / 2;
597 		if (block < le32_to_cpu(m->ee_block))
598 			r = m - 1;
599 		else
600 			l = m + 1;
601 		ext_debug("%p(%u):%p(%u):%p(%u) ", l, le32_to_cpu(l->ee_block),
602 				m, le32_to_cpu(m->ee_block),
603 				r, le32_to_cpu(r->ee_block));
604 	}
605 
606 	path->p_ext = l - 1;
607 	ext_debug("  -> %d:%llu:[%d]%d ",
608 			le32_to_cpu(path->p_ext->ee_block),
609 			ext4_ext_pblock(path->p_ext),
610 			ext4_ext_is_uninitialized(path->p_ext),
611 			ext4_ext_get_actual_len(path->p_ext));
612 
613 #ifdef CHECK_BINSEARCH
614 	{
615 		struct ext4_extent *chex, *ex;
616 		int k;
617 
618 		chex = ex = EXT_FIRST_EXTENT(eh);
619 		for (k = 0; k < le16_to_cpu(eh->eh_entries); k++, ex++) {
620 			BUG_ON(k && le32_to_cpu(ex->ee_block)
621 					  <= le32_to_cpu(ex[-1].ee_block));
622 			if (block < le32_to_cpu(ex->ee_block))
623 				break;
624 			chex = ex;
625 		}
626 		BUG_ON(chex != path->p_ext);
627 	}
628 #endif
629 
630 }
631 
632 int ext4_ext_tree_init(handle_t *handle, struct inode *inode)
633 {
634 	struct ext4_extent_header *eh;
635 
636 	eh = ext_inode_hdr(inode);
637 	eh->eh_depth = 0;
638 	eh->eh_entries = 0;
639 	eh->eh_magic = EXT4_EXT_MAGIC;
640 	eh->eh_max = cpu_to_le16(ext4_ext_space_root(inode, 0));
641 	ext4_mark_inode_dirty(handle, inode);
642 	ext4_ext_invalidate_cache(inode);
643 	return 0;
644 }
645 
646 struct ext4_ext_path *
647 ext4_ext_find_extent(struct inode *inode, ext4_lblk_t block,
648 					struct ext4_ext_path *path)
649 {
650 	struct ext4_extent_header *eh;
651 	struct buffer_head *bh;
652 	short int depth, i, ppos = 0, alloc = 0;
653 
654 	eh = ext_inode_hdr(inode);
655 	depth = ext_depth(inode);
656 
657 	/* account possible depth increase */
658 	if (!path) {
659 		path = kzalloc(sizeof(struct ext4_ext_path) * (depth + 2),
660 				GFP_NOFS);
661 		if (!path)
662 			return ERR_PTR(-ENOMEM);
663 		alloc = 1;
664 	}
665 	path[0].p_hdr = eh;
666 	path[0].p_bh = NULL;
667 
668 	i = depth;
669 	/* walk through the tree */
670 	while (i) {
671 		int need_to_validate = 0;
672 
673 		ext_debug("depth %d: num %d, max %d\n",
674 			  ppos, le16_to_cpu(eh->eh_entries), le16_to_cpu(eh->eh_max));
675 
676 		ext4_ext_binsearch_idx(inode, path + ppos, block);
677 		path[ppos].p_block = ext4_idx_pblock(path[ppos].p_idx);
678 		path[ppos].p_depth = i;
679 		path[ppos].p_ext = NULL;
680 
681 		bh = sb_getblk(inode->i_sb, path[ppos].p_block);
682 		if (unlikely(!bh))
683 			goto err;
684 		if (!bh_uptodate_or_lock(bh)) {
685 			trace_ext4_ext_load_extent(inode, block,
686 						path[ppos].p_block);
687 			if (bh_submit_read(bh) < 0) {
688 				put_bh(bh);
689 				goto err;
690 			}
691 			/* validate the extent entries */
692 			need_to_validate = 1;
693 		}
694 		eh = ext_block_hdr(bh);
695 		ppos++;
696 		if (unlikely(ppos > depth)) {
697 			put_bh(bh);
698 			EXT4_ERROR_INODE(inode,
699 					 "ppos %d > depth %d", ppos, depth);
700 			goto err;
701 		}
702 		path[ppos].p_bh = bh;
703 		path[ppos].p_hdr = eh;
704 		i--;
705 
706 		if (need_to_validate && ext4_ext_check(inode, eh, i))
707 			goto err;
708 	}
709 
710 	path[ppos].p_depth = i;
711 	path[ppos].p_ext = NULL;
712 	path[ppos].p_idx = NULL;
713 
714 	/* find extent */
715 	ext4_ext_binsearch(inode, path + ppos, block);
716 	/* if not an empty leaf */
717 	if (path[ppos].p_ext)
718 		path[ppos].p_block = ext4_ext_pblock(path[ppos].p_ext);
719 
720 	ext4_ext_show_path(inode, path);
721 
722 	return path;
723 
724 err:
725 	ext4_ext_drop_refs(path);
726 	if (alloc)
727 		kfree(path);
728 	return ERR_PTR(-EIO);
729 }
730 
731 /*
732  * ext4_ext_insert_index:
733  * insert new index [@logical;@ptr] into the block at @curp;
734  * check where to insert: before @curp or after @curp
735  */
736 static int ext4_ext_insert_index(handle_t *handle, struct inode *inode,
737 				 struct ext4_ext_path *curp,
738 				 int logical, ext4_fsblk_t ptr)
739 {
740 	struct ext4_extent_idx *ix;
741 	int len, err;
742 
743 	err = ext4_ext_get_access(handle, inode, curp);
744 	if (err)
745 		return err;
746 
747 	if (unlikely(logical == le32_to_cpu(curp->p_idx->ei_block))) {
748 		EXT4_ERROR_INODE(inode,
749 				 "logical %d == ei_block %d!",
750 				 logical, le32_to_cpu(curp->p_idx->ei_block));
751 		return -EIO;
752 	}
753 
754 	if (unlikely(le16_to_cpu(curp->p_hdr->eh_entries)
755 			     >= le16_to_cpu(curp->p_hdr->eh_max))) {
756 		EXT4_ERROR_INODE(inode,
757 				 "eh_entries %d >= eh_max %d!",
758 				 le16_to_cpu(curp->p_hdr->eh_entries),
759 				 le16_to_cpu(curp->p_hdr->eh_max));
760 		return -EIO;
761 	}
762 
763 	if (logical > le32_to_cpu(curp->p_idx->ei_block)) {
764 		/* insert after */
765 		ext_debug("insert new index %d after: %llu\n", logical, ptr);
766 		ix = curp->p_idx + 1;
767 	} else {
768 		/* insert before */
769 		ext_debug("insert new index %d before: %llu\n", logical, ptr);
770 		ix = curp->p_idx;
771 	}
772 
773 	len = EXT_LAST_INDEX(curp->p_hdr) - ix + 1;
774 	BUG_ON(len < 0);
775 	if (len > 0) {
776 		ext_debug("insert new index %d: "
777 				"move %d indices from 0x%p to 0x%p\n",
778 				logical, len, ix, ix + 1);
779 		memmove(ix + 1, ix, len * sizeof(struct ext4_extent_idx));
780 	}
781 
782 	if (unlikely(ix > EXT_MAX_INDEX(curp->p_hdr))) {
783 		EXT4_ERROR_INODE(inode, "ix > EXT_MAX_INDEX!");
784 		return -EIO;
785 	}
786 
787 	ix->ei_block = cpu_to_le32(logical);
788 	ext4_idx_store_pblock(ix, ptr);
789 	le16_add_cpu(&curp->p_hdr->eh_entries, 1);
790 
791 	if (unlikely(ix > EXT_LAST_INDEX(curp->p_hdr))) {
792 		EXT4_ERROR_INODE(inode, "ix > EXT_LAST_INDEX!");
793 		return -EIO;
794 	}
795 
796 	err = ext4_ext_dirty(handle, inode, curp);
797 	ext4_std_error(inode->i_sb, err);
798 
799 	return err;
800 }
801 
802 /*
803  * ext4_ext_split:
804  * inserts new subtree into the path, using free index entry
805  * at depth @at:
806  * - allocates all needed blocks (new leaf and all intermediate index blocks)
807  * - makes decision where to split
808  * - moves remaining extents and index entries (right to the split point)
809  *   into the newly allocated blocks
810  * - initializes subtree
811  */
812 static int ext4_ext_split(handle_t *handle, struct inode *inode,
813 			  unsigned int flags,
814 			  struct ext4_ext_path *path,
815 			  struct ext4_extent *newext, int at)
816 {
817 	struct buffer_head *bh = NULL;
818 	int depth = ext_depth(inode);
819 	struct ext4_extent_header *neh;
820 	struct ext4_extent_idx *fidx;
821 	int i = at, k, m, a;
822 	ext4_fsblk_t newblock, oldblock;
823 	__le32 border;
824 	ext4_fsblk_t *ablocks = NULL; /* array of allocated blocks */
825 	int err = 0;
826 
827 	/* make decision: where to split? */
828 	/* FIXME: now decision is simplest: at current extent */
829 
830 	/* if current leaf will be split, then we should use
831 	 * border from split point */
832 	if (unlikely(path[depth].p_ext > EXT_MAX_EXTENT(path[depth].p_hdr))) {
833 		EXT4_ERROR_INODE(inode, "p_ext > EXT_MAX_EXTENT!");
834 		return -EIO;
835 	}
836 	if (path[depth].p_ext != EXT_MAX_EXTENT(path[depth].p_hdr)) {
837 		border = path[depth].p_ext[1].ee_block;
838 		ext_debug("leaf will be split."
839 				" next leaf starts at %d\n",
840 				  le32_to_cpu(border));
841 	} else {
842 		border = newext->ee_block;
843 		ext_debug("leaf will be added."
844 				" next leaf starts at %d\n",
845 				le32_to_cpu(border));
846 	}
847 
848 	/*
849 	 * If error occurs, then we break processing
850 	 * and mark filesystem read-only. index won't
851 	 * be inserted and tree will be in consistent
852 	 * state. Next mount will repair buffers too.
853 	 */
854 
855 	/*
856 	 * Get array to track all allocated blocks.
857 	 * We need this to handle errors and free blocks
858 	 * upon them.
859 	 */
860 	ablocks = kzalloc(sizeof(ext4_fsblk_t) * depth, GFP_NOFS);
861 	if (!ablocks)
862 		return -ENOMEM;
863 
864 	/* allocate all needed blocks */
865 	ext_debug("allocate %d blocks for indexes/leaf\n", depth - at);
866 	for (a = 0; a < depth - at; a++) {
867 		newblock = ext4_ext_new_meta_block(handle, inode, path,
868 						   newext, &err, flags);
869 		if (newblock == 0)
870 			goto cleanup;
871 		ablocks[a] = newblock;
872 	}
873 
874 	/* initialize new leaf */
875 	newblock = ablocks[--a];
876 	if (unlikely(newblock == 0)) {
877 		EXT4_ERROR_INODE(inode, "newblock == 0!");
878 		err = -EIO;
879 		goto cleanup;
880 	}
881 	bh = sb_getblk(inode->i_sb, newblock);
882 	if (!bh) {
883 		err = -EIO;
884 		goto cleanup;
885 	}
886 	lock_buffer(bh);
887 
888 	err = ext4_journal_get_create_access(handle, bh);
889 	if (err)
890 		goto cleanup;
891 
892 	neh = ext_block_hdr(bh);
893 	neh->eh_entries = 0;
894 	neh->eh_max = cpu_to_le16(ext4_ext_space_block(inode, 0));
895 	neh->eh_magic = EXT4_EXT_MAGIC;
896 	neh->eh_depth = 0;
897 
898 	/* move remainder of path[depth] to the new leaf */
899 	if (unlikely(path[depth].p_hdr->eh_entries !=
900 		     path[depth].p_hdr->eh_max)) {
901 		EXT4_ERROR_INODE(inode, "eh_entries %d != eh_max %d!",
902 				 path[depth].p_hdr->eh_entries,
903 				 path[depth].p_hdr->eh_max);
904 		err = -EIO;
905 		goto cleanup;
906 	}
907 	/* start copy from next extent */
908 	m = EXT_MAX_EXTENT(path[depth].p_hdr) - path[depth].p_ext++;
909 	ext4_ext_show_move(inode, path, newblock, depth);
910 	if (m) {
911 		struct ext4_extent *ex;
912 		ex = EXT_FIRST_EXTENT(neh);
913 		memmove(ex, path[depth].p_ext, sizeof(struct ext4_extent) * m);
914 		le16_add_cpu(&neh->eh_entries, m);
915 	}
916 
917 	set_buffer_uptodate(bh);
918 	unlock_buffer(bh);
919 
920 	err = ext4_handle_dirty_metadata(handle, inode, bh);
921 	if (err)
922 		goto cleanup;
923 	brelse(bh);
924 	bh = NULL;
925 
926 	/* correct old leaf */
927 	if (m) {
928 		err = ext4_ext_get_access(handle, inode, path + depth);
929 		if (err)
930 			goto cleanup;
931 		le16_add_cpu(&path[depth].p_hdr->eh_entries, -m);
932 		err = ext4_ext_dirty(handle, inode, path + depth);
933 		if (err)
934 			goto cleanup;
935 
936 	}
937 
938 	/* create intermediate indexes */
939 	k = depth - at - 1;
940 	if (unlikely(k < 0)) {
941 		EXT4_ERROR_INODE(inode, "k %d < 0!", k);
942 		err = -EIO;
943 		goto cleanup;
944 	}
945 	if (k)
946 		ext_debug("create %d intermediate indices\n", k);
947 	/* insert new index into current index block */
948 	/* current depth stored in i var */
949 	i = depth - 1;
950 	while (k--) {
951 		oldblock = newblock;
952 		newblock = ablocks[--a];
953 		bh = sb_getblk(inode->i_sb, newblock);
954 		if (!bh) {
955 			err = -EIO;
956 			goto cleanup;
957 		}
958 		lock_buffer(bh);
959 
960 		err = ext4_journal_get_create_access(handle, bh);
961 		if (err)
962 			goto cleanup;
963 
964 		neh = ext_block_hdr(bh);
965 		neh->eh_entries = cpu_to_le16(1);
966 		neh->eh_magic = EXT4_EXT_MAGIC;
967 		neh->eh_max = cpu_to_le16(ext4_ext_space_block_idx(inode, 0));
968 		neh->eh_depth = cpu_to_le16(depth - i);
969 		fidx = EXT_FIRST_INDEX(neh);
970 		fidx->ei_block = border;
971 		ext4_idx_store_pblock(fidx, oldblock);
972 
973 		ext_debug("int.index at %d (block %llu): %u -> %llu\n",
974 				i, newblock, le32_to_cpu(border), oldblock);
975 
976 		/* move remainder of path[i] to the new index block */
977 		if (unlikely(EXT_MAX_INDEX(path[i].p_hdr) !=
978 					EXT_LAST_INDEX(path[i].p_hdr))) {
979 			EXT4_ERROR_INODE(inode,
980 					 "EXT_MAX_INDEX != EXT_LAST_INDEX ee_block %d!",
981 					 le32_to_cpu(path[i].p_ext->ee_block));
982 			err = -EIO;
983 			goto cleanup;
984 		}
985 		/* start copy indexes */
986 		m = EXT_MAX_INDEX(path[i].p_hdr) - path[i].p_idx++;
987 		ext_debug("cur 0x%p, last 0x%p\n", path[i].p_idx,
988 				EXT_MAX_INDEX(path[i].p_hdr));
989 		ext4_ext_show_move(inode, path, newblock, i);
990 		if (m) {
991 			memmove(++fidx, path[i].p_idx,
992 				sizeof(struct ext4_extent_idx) * m);
993 			le16_add_cpu(&neh->eh_entries, m);
994 		}
995 		set_buffer_uptodate(bh);
996 		unlock_buffer(bh);
997 
998 		err = ext4_handle_dirty_metadata(handle, inode, bh);
999 		if (err)
1000 			goto cleanup;
1001 		brelse(bh);
1002 		bh = NULL;
1003 
1004 		/* correct old index */
1005 		if (m) {
1006 			err = ext4_ext_get_access(handle, inode, path + i);
1007 			if (err)
1008 				goto cleanup;
1009 			le16_add_cpu(&path[i].p_hdr->eh_entries, -m);
1010 			err = ext4_ext_dirty(handle, inode, path + i);
1011 			if (err)
1012 				goto cleanup;
1013 		}
1014 
1015 		i--;
1016 	}
1017 
1018 	/* insert new index */
1019 	err = ext4_ext_insert_index(handle, inode, path + at,
1020 				    le32_to_cpu(border), newblock);
1021 
1022 cleanup:
1023 	if (bh) {
1024 		if (buffer_locked(bh))
1025 			unlock_buffer(bh);
1026 		brelse(bh);
1027 	}
1028 
1029 	if (err) {
1030 		/* free all allocated blocks in error case */
1031 		for (i = 0; i < depth; i++) {
1032 			if (!ablocks[i])
1033 				continue;
1034 			ext4_free_blocks(handle, inode, NULL, ablocks[i], 1,
1035 					 EXT4_FREE_BLOCKS_METADATA);
1036 		}
1037 	}
1038 	kfree(ablocks);
1039 
1040 	return err;
1041 }
1042 
1043 /*
1044  * ext4_ext_grow_indepth:
1045  * implements tree growing procedure:
1046  * - allocates new block
1047  * - moves top-level data (index block or leaf) into the new block
1048  * - initializes new top-level, creating index that points to the
1049  *   just created block
1050  */
1051 static int ext4_ext_grow_indepth(handle_t *handle, struct inode *inode,
1052 				 unsigned int flags,
1053 				 struct ext4_extent *newext)
1054 {
1055 	struct ext4_extent_header *neh;
1056 	struct buffer_head *bh;
1057 	ext4_fsblk_t newblock;
1058 	int err = 0;
1059 
1060 	newblock = ext4_ext_new_meta_block(handle, inode, NULL,
1061 		newext, &err, flags);
1062 	if (newblock == 0)
1063 		return err;
1064 
1065 	bh = sb_getblk(inode->i_sb, newblock);
1066 	if (!bh) {
1067 		err = -EIO;
1068 		ext4_std_error(inode->i_sb, err);
1069 		return err;
1070 	}
1071 	lock_buffer(bh);
1072 
1073 	err = ext4_journal_get_create_access(handle, bh);
1074 	if (err) {
1075 		unlock_buffer(bh);
1076 		goto out;
1077 	}
1078 
1079 	/* move top-level index/leaf into new block */
1080 	memmove(bh->b_data, EXT4_I(inode)->i_data,
1081 		sizeof(EXT4_I(inode)->i_data));
1082 
1083 	/* set size of new block */
1084 	neh = ext_block_hdr(bh);
1085 	/* old root could have indexes or leaves
1086 	 * so calculate e_max right way */
1087 	if (ext_depth(inode))
1088 		neh->eh_max = cpu_to_le16(ext4_ext_space_block_idx(inode, 0));
1089 	else
1090 		neh->eh_max = cpu_to_le16(ext4_ext_space_block(inode, 0));
1091 	neh->eh_magic = EXT4_EXT_MAGIC;
1092 	set_buffer_uptodate(bh);
1093 	unlock_buffer(bh);
1094 
1095 	err = ext4_handle_dirty_metadata(handle, inode, bh);
1096 	if (err)
1097 		goto out;
1098 
1099 	/* Update top-level index: num,max,pointer */
1100 	neh = ext_inode_hdr(inode);
1101 	neh->eh_entries = cpu_to_le16(1);
1102 	ext4_idx_store_pblock(EXT_FIRST_INDEX(neh), newblock);
1103 	if (neh->eh_depth == 0) {
1104 		/* Root extent block becomes index block */
1105 		neh->eh_max = cpu_to_le16(ext4_ext_space_root_idx(inode, 0));
1106 		EXT_FIRST_INDEX(neh)->ei_block =
1107 			EXT_FIRST_EXTENT(neh)->ee_block;
1108 	}
1109 	ext_debug("new root: num %d(%d), lblock %d, ptr %llu\n",
1110 		  le16_to_cpu(neh->eh_entries), le16_to_cpu(neh->eh_max),
1111 		  le32_to_cpu(EXT_FIRST_INDEX(neh)->ei_block),
1112 		  ext4_idx_pblock(EXT_FIRST_INDEX(neh)));
1113 
1114 	neh->eh_depth = cpu_to_le16(le16_to_cpu(neh->eh_depth) + 1);
1115 	ext4_mark_inode_dirty(handle, inode);
1116 out:
1117 	brelse(bh);
1118 
1119 	return err;
1120 }
1121 
1122 /*
1123  * ext4_ext_create_new_leaf:
1124  * finds empty index and adds new leaf.
1125  * if no free index is found, then it requests in-depth growing.
1126  */
1127 static int ext4_ext_create_new_leaf(handle_t *handle, struct inode *inode,
1128 				    unsigned int flags,
1129 				    struct ext4_ext_path *path,
1130 				    struct ext4_extent *newext)
1131 {
1132 	struct ext4_ext_path *curp;
1133 	int depth, i, err = 0;
1134 
1135 repeat:
1136 	i = depth = ext_depth(inode);
1137 
1138 	/* walk up to the tree and look for free index entry */
1139 	curp = path + depth;
1140 	while (i > 0 && !EXT_HAS_FREE_INDEX(curp)) {
1141 		i--;
1142 		curp--;
1143 	}
1144 
1145 	/* we use already allocated block for index block,
1146 	 * so subsequent data blocks should be contiguous */
1147 	if (EXT_HAS_FREE_INDEX(curp)) {
1148 		/* if we found index with free entry, then use that
1149 		 * entry: create all needed subtree and add new leaf */
1150 		err = ext4_ext_split(handle, inode, flags, path, newext, i);
1151 		if (err)
1152 			goto out;
1153 
1154 		/* refill path */
1155 		ext4_ext_drop_refs(path);
1156 		path = ext4_ext_find_extent(inode,
1157 				    (ext4_lblk_t)le32_to_cpu(newext->ee_block),
1158 				    path);
1159 		if (IS_ERR(path))
1160 			err = PTR_ERR(path);
1161 	} else {
1162 		/* tree is full, time to grow in depth */
1163 		err = ext4_ext_grow_indepth(handle, inode, flags, newext);
1164 		if (err)
1165 			goto out;
1166 
1167 		/* refill path */
1168 		ext4_ext_drop_refs(path);
1169 		path = ext4_ext_find_extent(inode,
1170 				   (ext4_lblk_t)le32_to_cpu(newext->ee_block),
1171 				    path);
1172 		if (IS_ERR(path)) {
1173 			err = PTR_ERR(path);
1174 			goto out;
1175 		}
1176 
1177 		/*
1178 		 * only first (depth 0 -> 1) produces free space;
1179 		 * in all other cases we have to split the grown tree
1180 		 */
1181 		depth = ext_depth(inode);
1182 		if (path[depth].p_hdr->eh_entries == path[depth].p_hdr->eh_max) {
1183 			/* now we need to split */
1184 			goto repeat;
1185 		}
1186 	}
1187 
1188 out:
1189 	return err;
1190 }
1191 
1192 /*
1193  * search the closest allocated block to the left for *logical
1194  * and returns it at @logical + it's physical address at @phys
1195  * if *logical is the smallest allocated block, the function
1196  * returns 0 at @phys
1197  * return value contains 0 (success) or error code
1198  */
1199 static int ext4_ext_search_left(struct inode *inode,
1200 				struct ext4_ext_path *path,
1201 				ext4_lblk_t *logical, ext4_fsblk_t *phys)
1202 {
1203 	struct ext4_extent_idx *ix;
1204 	struct ext4_extent *ex;
1205 	int depth, ee_len;
1206 
1207 	if (unlikely(path == NULL)) {
1208 		EXT4_ERROR_INODE(inode, "path == NULL *logical %d!", *logical);
1209 		return -EIO;
1210 	}
1211 	depth = path->p_depth;
1212 	*phys = 0;
1213 
1214 	if (depth == 0 && path->p_ext == NULL)
1215 		return 0;
1216 
1217 	/* usually extent in the path covers blocks smaller
1218 	 * then *logical, but it can be that extent is the
1219 	 * first one in the file */
1220 
1221 	ex = path[depth].p_ext;
1222 	ee_len = ext4_ext_get_actual_len(ex);
1223 	if (*logical < le32_to_cpu(ex->ee_block)) {
1224 		if (unlikely(EXT_FIRST_EXTENT(path[depth].p_hdr) != ex)) {
1225 			EXT4_ERROR_INODE(inode,
1226 					 "EXT_FIRST_EXTENT != ex *logical %d ee_block %d!",
1227 					 *logical, le32_to_cpu(ex->ee_block));
1228 			return -EIO;
1229 		}
1230 		while (--depth >= 0) {
1231 			ix = path[depth].p_idx;
1232 			if (unlikely(ix != EXT_FIRST_INDEX(path[depth].p_hdr))) {
1233 				EXT4_ERROR_INODE(inode,
1234 				  "ix (%d) != EXT_FIRST_INDEX (%d) (depth %d)!",
1235 				  ix != NULL ? le32_to_cpu(ix->ei_block) : 0,
1236 				  EXT_FIRST_INDEX(path[depth].p_hdr) != NULL ?
1237 		le32_to_cpu(EXT_FIRST_INDEX(path[depth].p_hdr)->ei_block) : 0,
1238 				  depth);
1239 				return -EIO;
1240 			}
1241 		}
1242 		return 0;
1243 	}
1244 
1245 	if (unlikely(*logical < (le32_to_cpu(ex->ee_block) + ee_len))) {
1246 		EXT4_ERROR_INODE(inode,
1247 				 "logical %d < ee_block %d + ee_len %d!",
1248 				 *logical, le32_to_cpu(ex->ee_block), ee_len);
1249 		return -EIO;
1250 	}
1251 
1252 	*logical = le32_to_cpu(ex->ee_block) + ee_len - 1;
1253 	*phys = ext4_ext_pblock(ex) + ee_len - 1;
1254 	return 0;
1255 }
1256 
1257 /*
1258  * search the closest allocated block to the right for *logical
1259  * and returns it at @logical + it's physical address at @phys
1260  * if *logical is the largest allocated block, the function
1261  * returns 0 at @phys
1262  * return value contains 0 (success) or error code
1263  */
1264 static int ext4_ext_search_right(struct inode *inode,
1265 				 struct ext4_ext_path *path,
1266 				 ext4_lblk_t *logical, ext4_fsblk_t *phys,
1267 				 struct ext4_extent **ret_ex)
1268 {
1269 	struct buffer_head *bh = NULL;
1270 	struct ext4_extent_header *eh;
1271 	struct ext4_extent_idx *ix;
1272 	struct ext4_extent *ex;
1273 	ext4_fsblk_t block;
1274 	int depth;	/* Note, NOT eh_depth; depth from top of tree */
1275 	int ee_len;
1276 
1277 	if (unlikely(path == NULL)) {
1278 		EXT4_ERROR_INODE(inode, "path == NULL *logical %d!", *logical);
1279 		return -EIO;
1280 	}
1281 	depth = path->p_depth;
1282 	*phys = 0;
1283 
1284 	if (depth == 0 && path->p_ext == NULL)
1285 		return 0;
1286 
1287 	/* usually extent in the path covers blocks smaller
1288 	 * then *logical, but it can be that extent is the
1289 	 * first one in the file */
1290 
1291 	ex = path[depth].p_ext;
1292 	ee_len = ext4_ext_get_actual_len(ex);
1293 	if (*logical < le32_to_cpu(ex->ee_block)) {
1294 		if (unlikely(EXT_FIRST_EXTENT(path[depth].p_hdr) != ex)) {
1295 			EXT4_ERROR_INODE(inode,
1296 					 "first_extent(path[%d].p_hdr) != ex",
1297 					 depth);
1298 			return -EIO;
1299 		}
1300 		while (--depth >= 0) {
1301 			ix = path[depth].p_idx;
1302 			if (unlikely(ix != EXT_FIRST_INDEX(path[depth].p_hdr))) {
1303 				EXT4_ERROR_INODE(inode,
1304 						 "ix != EXT_FIRST_INDEX *logical %d!",
1305 						 *logical);
1306 				return -EIO;
1307 			}
1308 		}
1309 		goto found_extent;
1310 	}
1311 
1312 	if (unlikely(*logical < (le32_to_cpu(ex->ee_block) + ee_len))) {
1313 		EXT4_ERROR_INODE(inode,
1314 				 "logical %d < ee_block %d + ee_len %d!",
1315 				 *logical, le32_to_cpu(ex->ee_block), ee_len);
1316 		return -EIO;
1317 	}
1318 
1319 	if (ex != EXT_LAST_EXTENT(path[depth].p_hdr)) {
1320 		/* next allocated block in this leaf */
1321 		ex++;
1322 		goto found_extent;
1323 	}
1324 
1325 	/* go up and search for index to the right */
1326 	while (--depth >= 0) {
1327 		ix = path[depth].p_idx;
1328 		if (ix != EXT_LAST_INDEX(path[depth].p_hdr))
1329 			goto got_index;
1330 	}
1331 
1332 	/* we've gone up to the root and found no index to the right */
1333 	return 0;
1334 
1335 got_index:
1336 	/* we've found index to the right, let's
1337 	 * follow it and find the closest allocated
1338 	 * block to the right */
1339 	ix++;
1340 	block = ext4_idx_pblock(ix);
1341 	while (++depth < path->p_depth) {
1342 		bh = sb_bread(inode->i_sb, block);
1343 		if (bh == NULL)
1344 			return -EIO;
1345 		eh = ext_block_hdr(bh);
1346 		/* subtract from p_depth to get proper eh_depth */
1347 		if (ext4_ext_check(inode, eh, path->p_depth - depth)) {
1348 			put_bh(bh);
1349 			return -EIO;
1350 		}
1351 		ix = EXT_FIRST_INDEX(eh);
1352 		block = ext4_idx_pblock(ix);
1353 		put_bh(bh);
1354 	}
1355 
1356 	bh = sb_bread(inode->i_sb, block);
1357 	if (bh == NULL)
1358 		return -EIO;
1359 	eh = ext_block_hdr(bh);
1360 	if (ext4_ext_check(inode, eh, path->p_depth - depth)) {
1361 		put_bh(bh);
1362 		return -EIO;
1363 	}
1364 	ex = EXT_FIRST_EXTENT(eh);
1365 found_extent:
1366 	*logical = le32_to_cpu(ex->ee_block);
1367 	*phys = ext4_ext_pblock(ex);
1368 	*ret_ex = ex;
1369 	if (bh)
1370 		put_bh(bh);
1371 	return 0;
1372 }
1373 
1374 /*
1375  * ext4_ext_next_allocated_block:
1376  * returns allocated block in subsequent extent or EXT_MAX_BLOCKS.
1377  * NOTE: it considers block number from index entry as
1378  * allocated block. Thus, index entries have to be consistent
1379  * with leaves.
1380  */
1381 static ext4_lblk_t
1382 ext4_ext_next_allocated_block(struct ext4_ext_path *path)
1383 {
1384 	int depth;
1385 
1386 	BUG_ON(path == NULL);
1387 	depth = path->p_depth;
1388 
1389 	if (depth == 0 && path->p_ext == NULL)
1390 		return EXT_MAX_BLOCKS;
1391 
1392 	while (depth >= 0) {
1393 		if (depth == path->p_depth) {
1394 			/* leaf */
1395 			if (path[depth].p_ext &&
1396 				path[depth].p_ext !=
1397 					EXT_LAST_EXTENT(path[depth].p_hdr))
1398 			  return le32_to_cpu(path[depth].p_ext[1].ee_block);
1399 		} else {
1400 			/* index */
1401 			if (path[depth].p_idx !=
1402 					EXT_LAST_INDEX(path[depth].p_hdr))
1403 			  return le32_to_cpu(path[depth].p_idx[1].ei_block);
1404 		}
1405 		depth--;
1406 	}
1407 
1408 	return EXT_MAX_BLOCKS;
1409 }
1410 
1411 /*
1412  * ext4_ext_next_leaf_block:
1413  * returns first allocated block from next leaf or EXT_MAX_BLOCKS
1414  */
1415 static ext4_lblk_t ext4_ext_next_leaf_block(struct ext4_ext_path *path)
1416 {
1417 	int depth;
1418 
1419 	BUG_ON(path == NULL);
1420 	depth = path->p_depth;
1421 
1422 	/* zero-tree has no leaf blocks at all */
1423 	if (depth == 0)
1424 		return EXT_MAX_BLOCKS;
1425 
1426 	/* go to index block */
1427 	depth--;
1428 
1429 	while (depth >= 0) {
1430 		if (path[depth].p_idx !=
1431 				EXT_LAST_INDEX(path[depth].p_hdr))
1432 			return (ext4_lblk_t)
1433 				le32_to_cpu(path[depth].p_idx[1].ei_block);
1434 		depth--;
1435 	}
1436 
1437 	return EXT_MAX_BLOCKS;
1438 }
1439 
1440 /*
1441  * ext4_ext_correct_indexes:
1442  * if leaf gets modified and modified extent is first in the leaf,
1443  * then we have to correct all indexes above.
1444  * TODO: do we need to correct tree in all cases?
1445  */
1446 static int ext4_ext_correct_indexes(handle_t *handle, struct inode *inode,
1447 				struct ext4_ext_path *path)
1448 {
1449 	struct ext4_extent_header *eh;
1450 	int depth = ext_depth(inode);
1451 	struct ext4_extent *ex;
1452 	__le32 border;
1453 	int k, err = 0;
1454 
1455 	eh = path[depth].p_hdr;
1456 	ex = path[depth].p_ext;
1457 
1458 	if (unlikely(ex == NULL || eh == NULL)) {
1459 		EXT4_ERROR_INODE(inode,
1460 				 "ex %p == NULL or eh %p == NULL", ex, eh);
1461 		return -EIO;
1462 	}
1463 
1464 	if (depth == 0) {
1465 		/* there is no tree at all */
1466 		return 0;
1467 	}
1468 
1469 	if (ex != EXT_FIRST_EXTENT(eh)) {
1470 		/* we correct tree if first leaf got modified only */
1471 		return 0;
1472 	}
1473 
1474 	/*
1475 	 * TODO: we need correction if border is smaller than current one
1476 	 */
1477 	k = depth - 1;
1478 	border = path[depth].p_ext->ee_block;
1479 	err = ext4_ext_get_access(handle, inode, path + k);
1480 	if (err)
1481 		return err;
1482 	path[k].p_idx->ei_block = border;
1483 	err = ext4_ext_dirty(handle, inode, path + k);
1484 	if (err)
1485 		return err;
1486 
1487 	while (k--) {
1488 		/* change all left-side indexes */
1489 		if (path[k+1].p_idx != EXT_FIRST_INDEX(path[k+1].p_hdr))
1490 			break;
1491 		err = ext4_ext_get_access(handle, inode, path + k);
1492 		if (err)
1493 			break;
1494 		path[k].p_idx->ei_block = border;
1495 		err = ext4_ext_dirty(handle, inode, path + k);
1496 		if (err)
1497 			break;
1498 	}
1499 
1500 	return err;
1501 }
1502 
1503 int
1504 ext4_can_extents_be_merged(struct inode *inode, struct ext4_extent *ex1,
1505 				struct ext4_extent *ex2)
1506 {
1507 	unsigned short ext1_ee_len, ext2_ee_len, max_len;
1508 
1509 	/*
1510 	 * Make sure that either both extents are uninitialized, or
1511 	 * both are _not_.
1512 	 */
1513 	if (ext4_ext_is_uninitialized(ex1) ^ ext4_ext_is_uninitialized(ex2))
1514 		return 0;
1515 
1516 	if (ext4_ext_is_uninitialized(ex1))
1517 		max_len = EXT_UNINIT_MAX_LEN;
1518 	else
1519 		max_len = EXT_INIT_MAX_LEN;
1520 
1521 	ext1_ee_len = ext4_ext_get_actual_len(ex1);
1522 	ext2_ee_len = ext4_ext_get_actual_len(ex2);
1523 
1524 	if (le32_to_cpu(ex1->ee_block) + ext1_ee_len !=
1525 			le32_to_cpu(ex2->ee_block))
1526 		return 0;
1527 
1528 	/*
1529 	 * To allow future support for preallocated extents to be added
1530 	 * as an RO_COMPAT feature, refuse to merge to extents if
1531 	 * this can result in the top bit of ee_len being set.
1532 	 */
1533 	if (ext1_ee_len + ext2_ee_len > max_len)
1534 		return 0;
1535 #ifdef AGGRESSIVE_TEST
1536 	if (ext1_ee_len >= 4)
1537 		return 0;
1538 #endif
1539 
1540 	if (ext4_ext_pblock(ex1) + ext1_ee_len == ext4_ext_pblock(ex2))
1541 		return 1;
1542 	return 0;
1543 }
1544 
1545 /*
1546  * This function tries to merge the "ex" extent to the next extent in the tree.
1547  * It always tries to merge towards right. If you want to merge towards
1548  * left, pass "ex - 1" as argument instead of "ex".
1549  * Returns 0 if the extents (ex and ex+1) were _not_ merged and returns
1550  * 1 if they got merged.
1551  */
1552 static int ext4_ext_try_to_merge_right(struct inode *inode,
1553 				 struct ext4_ext_path *path,
1554 				 struct ext4_extent *ex)
1555 {
1556 	struct ext4_extent_header *eh;
1557 	unsigned int depth, len;
1558 	int merge_done = 0;
1559 	int uninitialized = 0;
1560 
1561 	depth = ext_depth(inode);
1562 	BUG_ON(path[depth].p_hdr == NULL);
1563 	eh = path[depth].p_hdr;
1564 
1565 	while (ex < EXT_LAST_EXTENT(eh)) {
1566 		if (!ext4_can_extents_be_merged(inode, ex, ex + 1))
1567 			break;
1568 		/* merge with next extent! */
1569 		if (ext4_ext_is_uninitialized(ex))
1570 			uninitialized = 1;
1571 		ex->ee_len = cpu_to_le16(ext4_ext_get_actual_len(ex)
1572 				+ ext4_ext_get_actual_len(ex + 1));
1573 		if (uninitialized)
1574 			ext4_ext_mark_uninitialized(ex);
1575 
1576 		if (ex + 1 < EXT_LAST_EXTENT(eh)) {
1577 			len = (EXT_LAST_EXTENT(eh) - ex - 1)
1578 				* sizeof(struct ext4_extent);
1579 			memmove(ex + 1, ex + 2, len);
1580 		}
1581 		le16_add_cpu(&eh->eh_entries, -1);
1582 		merge_done = 1;
1583 		WARN_ON(eh->eh_entries == 0);
1584 		if (!eh->eh_entries)
1585 			EXT4_ERROR_INODE(inode, "eh->eh_entries = 0!");
1586 	}
1587 
1588 	return merge_done;
1589 }
1590 
1591 /*
1592  * This function tries to merge the @ex extent to neighbours in the tree.
1593  * return 1 if merge left else 0.
1594  */
1595 static int ext4_ext_try_to_merge(struct inode *inode,
1596 				  struct ext4_ext_path *path,
1597 				  struct ext4_extent *ex) {
1598 	struct ext4_extent_header *eh;
1599 	unsigned int depth;
1600 	int merge_done = 0;
1601 	int ret = 0;
1602 
1603 	depth = ext_depth(inode);
1604 	BUG_ON(path[depth].p_hdr == NULL);
1605 	eh = path[depth].p_hdr;
1606 
1607 	if (ex > EXT_FIRST_EXTENT(eh))
1608 		merge_done = ext4_ext_try_to_merge_right(inode, path, ex - 1);
1609 
1610 	if (!merge_done)
1611 		ret = ext4_ext_try_to_merge_right(inode, path, ex);
1612 
1613 	return ret;
1614 }
1615 
1616 /*
1617  * check if a portion of the "newext" extent overlaps with an
1618  * existing extent.
1619  *
1620  * If there is an overlap discovered, it updates the length of the newext
1621  * such that there will be no overlap, and then returns 1.
1622  * If there is no overlap found, it returns 0.
1623  */
1624 static unsigned int ext4_ext_check_overlap(struct ext4_sb_info *sbi,
1625 					   struct inode *inode,
1626 					   struct ext4_extent *newext,
1627 					   struct ext4_ext_path *path)
1628 {
1629 	ext4_lblk_t b1, b2;
1630 	unsigned int depth, len1;
1631 	unsigned int ret = 0;
1632 
1633 	b1 = le32_to_cpu(newext->ee_block);
1634 	len1 = ext4_ext_get_actual_len(newext);
1635 	depth = ext_depth(inode);
1636 	if (!path[depth].p_ext)
1637 		goto out;
1638 	b2 = le32_to_cpu(path[depth].p_ext->ee_block);
1639 	b2 &= ~(sbi->s_cluster_ratio - 1);
1640 
1641 	/*
1642 	 * get the next allocated block if the extent in the path
1643 	 * is before the requested block(s)
1644 	 */
1645 	if (b2 < b1) {
1646 		b2 = ext4_ext_next_allocated_block(path);
1647 		if (b2 == EXT_MAX_BLOCKS)
1648 			goto out;
1649 		b2 &= ~(sbi->s_cluster_ratio - 1);
1650 	}
1651 
1652 	/* check for wrap through zero on extent logical start block*/
1653 	if (b1 + len1 < b1) {
1654 		len1 = EXT_MAX_BLOCKS - b1;
1655 		newext->ee_len = cpu_to_le16(len1);
1656 		ret = 1;
1657 	}
1658 
1659 	/* check for overlap */
1660 	if (b1 + len1 > b2) {
1661 		newext->ee_len = cpu_to_le16(b2 - b1);
1662 		ret = 1;
1663 	}
1664 out:
1665 	return ret;
1666 }
1667 
1668 /*
1669  * ext4_ext_insert_extent:
1670  * tries to merge requsted extent into the existing extent or
1671  * inserts requested extent as new one into the tree,
1672  * creating new leaf in the no-space case.
1673  */
1674 int ext4_ext_insert_extent(handle_t *handle, struct inode *inode,
1675 				struct ext4_ext_path *path,
1676 				struct ext4_extent *newext, int flag)
1677 {
1678 	struct ext4_extent_header *eh;
1679 	struct ext4_extent *ex, *fex;
1680 	struct ext4_extent *nearex; /* nearest extent */
1681 	struct ext4_ext_path *npath = NULL;
1682 	int depth, len, err;
1683 	ext4_lblk_t next;
1684 	unsigned uninitialized = 0;
1685 	int flags = 0;
1686 
1687 	if (unlikely(ext4_ext_get_actual_len(newext) == 0)) {
1688 		EXT4_ERROR_INODE(inode, "ext4_ext_get_actual_len(newext) == 0");
1689 		return -EIO;
1690 	}
1691 	depth = ext_depth(inode);
1692 	ex = path[depth].p_ext;
1693 	if (unlikely(path[depth].p_hdr == NULL)) {
1694 		EXT4_ERROR_INODE(inode, "path[%d].p_hdr == NULL", depth);
1695 		return -EIO;
1696 	}
1697 
1698 	/* try to insert block into found extent and return */
1699 	if (ex && !(flag & EXT4_GET_BLOCKS_PRE_IO)
1700 		&& ext4_can_extents_be_merged(inode, ex, newext)) {
1701 		ext_debug("append [%d]%d block to %u:[%d]%d (from %llu)\n",
1702 			  ext4_ext_is_uninitialized(newext),
1703 			  ext4_ext_get_actual_len(newext),
1704 			  le32_to_cpu(ex->ee_block),
1705 			  ext4_ext_is_uninitialized(ex),
1706 			  ext4_ext_get_actual_len(ex),
1707 			  ext4_ext_pblock(ex));
1708 		err = ext4_ext_get_access(handle, inode, path + depth);
1709 		if (err)
1710 			return err;
1711 
1712 		/*
1713 		 * ext4_can_extents_be_merged should have checked that either
1714 		 * both extents are uninitialized, or both aren't. Thus we
1715 		 * need to check only one of them here.
1716 		 */
1717 		if (ext4_ext_is_uninitialized(ex))
1718 			uninitialized = 1;
1719 		ex->ee_len = cpu_to_le16(ext4_ext_get_actual_len(ex)
1720 					+ ext4_ext_get_actual_len(newext));
1721 		if (uninitialized)
1722 			ext4_ext_mark_uninitialized(ex);
1723 		eh = path[depth].p_hdr;
1724 		nearex = ex;
1725 		goto merge;
1726 	}
1727 
1728 	depth = ext_depth(inode);
1729 	eh = path[depth].p_hdr;
1730 	if (le16_to_cpu(eh->eh_entries) < le16_to_cpu(eh->eh_max))
1731 		goto has_space;
1732 
1733 	/* probably next leaf has space for us? */
1734 	fex = EXT_LAST_EXTENT(eh);
1735 	next = EXT_MAX_BLOCKS;
1736 	if (le32_to_cpu(newext->ee_block) > le32_to_cpu(fex->ee_block))
1737 		next = ext4_ext_next_leaf_block(path);
1738 	if (next != EXT_MAX_BLOCKS) {
1739 		ext_debug("next leaf block - %u\n", next);
1740 		BUG_ON(npath != NULL);
1741 		npath = ext4_ext_find_extent(inode, next, NULL);
1742 		if (IS_ERR(npath))
1743 			return PTR_ERR(npath);
1744 		BUG_ON(npath->p_depth != path->p_depth);
1745 		eh = npath[depth].p_hdr;
1746 		if (le16_to_cpu(eh->eh_entries) < le16_to_cpu(eh->eh_max)) {
1747 			ext_debug("next leaf isn't full(%d)\n",
1748 				  le16_to_cpu(eh->eh_entries));
1749 			path = npath;
1750 			goto has_space;
1751 		}
1752 		ext_debug("next leaf has no free space(%d,%d)\n",
1753 			  le16_to_cpu(eh->eh_entries), le16_to_cpu(eh->eh_max));
1754 	}
1755 
1756 	/*
1757 	 * There is no free space in the found leaf.
1758 	 * We're gonna add a new leaf in the tree.
1759 	 */
1760 	if (flag & EXT4_GET_BLOCKS_PUNCH_OUT_EXT)
1761 		flags = EXT4_MB_USE_ROOT_BLOCKS;
1762 	err = ext4_ext_create_new_leaf(handle, inode, flags, path, newext);
1763 	if (err)
1764 		goto cleanup;
1765 	depth = ext_depth(inode);
1766 	eh = path[depth].p_hdr;
1767 
1768 has_space:
1769 	nearex = path[depth].p_ext;
1770 
1771 	err = ext4_ext_get_access(handle, inode, path + depth);
1772 	if (err)
1773 		goto cleanup;
1774 
1775 	if (!nearex) {
1776 		/* there is no extent in this leaf, create first one */
1777 		ext_debug("first extent in the leaf: %u:%llu:[%d]%d\n",
1778 				le32_to_cpu(newext->ee_block),
1779 				ext4_ext_pblock(newext),
1780 				ext4_ext_is_uninitialized(newext),
1781 				ext4_ext_get_actual_len(newext));
1782 		nearex = EXT_FIRST_EXTENT(eh);
1783 	} else {
1784 		if (le32_to_cpu(newext->ee_block)
1785 			   > le32_to_cpu(nearex->ee_block)) {
1786 			/* Insert after */
1787 			ext_debug("insert %u:%llu:[%d]%d before: "
1788 					"nearest %p\n",
1789 					le32_to_cpu(newext->ee_block),
1790 					ext4_ext_pblock(newext),
1791 					ext4_ext_is_uninitialized(newext),
1792 					ext4_ext_get_actual_len(newext),
1793 					nearex);
1794 			nearex++;
1795 		} else {
1796 			/* Insert before */
1797 			BUG_ON(newext->ee_block == nearex->ee_block);
1798 			ext_debug("insert %u:%llu:[%d]%d after: "
1799 					"nearest %p\n",
1800 					le32_to_cpu(newext->ee_block),
1801 					ext4_ext_pblock(newext),
1802 					ext4_ext_is_uninitialized(newext),
1803 					ext4_ext_get_actual_len(newext),
1804 					nearex);
1805 		}
1806 		len = EXT_LAST_EXTENT(eh) - nearex + 1;
1807 		if (len > 0) {
1808 			ext_debug("insert %u:%llu:[%d]%d: "
1809 					"move %d extents from 0x%p to 0x%p\n",
1810 					le32_to_cpu(newext->ee_block),
1811 					ext4_ext_pblock(newext),
1812 					ext4_ext_is_uninitialized(newext),
1813 					ext4_ext_get_actual_len(newext),
1814 					len, nearex, nearex + 1);
1815 			memmove(nearex + 1, nearex,
1816 				len * sizeof(struct ext4_extent));
1817 		}
1818 	}
1819 
1820 	le16_add_cpu(&eh->eh_entries, 1);
1821 	path[depth].p_ext = nearex;
1822 	nearex->ee_block = newext->ee_block;
1823 	ext4_ext_store_pblock(nearex, ext4_ext_pblock(newext));
1824 	nearex->ee_len = newext->ee_len;
1825 
1826 merge:
1827 	/* try to merge extents to the right */
1828 	if (!(flag & EXT4_GET_BLOCKS_PRE_IO))
1829 		ext4_ext_try_to_merge(inode, path, nearex);
1830 
1831 	/* try to merge extents to the left */
1832 
1833 	/* time to correct all indexes above */
1834 	err = ext4_ext_correct_indexes(handle, inode, path);
1835 	if (err)
1836 		goto cleanup;
1837 
1838 	err = ext4_ext_dirty(handle, inode, path + depth);
1839 
1840 cleanup:
1841 	if (npath) {
1842 		ext4_ext_drop_refs(npath);
1843 		kfree(npath);
1844 	}
1845 	ext4_ext_invalidate_cache(inode);
1846 	return err;
1847 }
1848 
1849 static int ext4_ext_walk_space(struct inode *inode, ext4_lblk_t block,
1850 			       ext4_lblk_t num, ext_prepare_callback func,
1851 			       void *cbdata)
1852 {
1853 	struct ext4_ext_path *path = NULL;
1854 	struct ext4_ext_cache cbex;
1855 	struct ext4_extent *ex;
1856 	ext4_lblk_t next, start = 0, end = 0;
1857 	ext4_lblk_t last = block + num;
1858 	int depth, exists, err = 0;
1859 
1860 	BUG_ON(func == NULL);
1861 	BUG_ON(inode == NULL);
1862 
1863 	while (block < last && block != EXT_MAX_BLOCKS) {
1864 		num = last - block;
1865 		/* find extent for this block */
1866 		down_read(&EXT4_I(inode)->i_data_sem);
1867 		path = ext4_ext_find_extent(inode, block, path);
1868 		up_read(&EXT4_I(inode)->i_data_sem);
1869 		if (IS_ERR(path)) {
1870 			err = PTR_ERR(path);
1871 			path = NULL;
1872 			break;
1873 		}
1874 
1875 		depth = ext_depth(inode);
1876 		if (unlikely(path[depth].p_hdr == NULL)) {
1877 			EXT4_ERROR_INODE(inode, "path[%d].p_hdr == NULL", depth);
1878 			err = -EIO;
1879 			break;
1880 		}
1881 		ex = path[depth].p_ext;
1882 		next = ext4_ext_next_allocated_block(path);
1883 
1884 		exists = 0;
1885 		if (!ex) {
1886 			/* there is no extent yet, so try to allocate
1887 			 * all requested space */
1888 			start = block;
1889 			end = block + num;
1890 		} else if (le32_to_cpu(ex->ee_block) > block) {
1891 			/* need to allocate space before found extent */
1892 			start = block;
1893 			end = le32_to_cpu(ex->ee_block);
1894 			if (block + num < end)
1895 				end = block + num;
1896 		} else if (block >= le32_to_cpu(ex->ee_block)
1897 					+ ext4_ext_get_actual_len(ex)) {
1898 			/* need to allocate space after found extent */
1899 			start = block;
1900 			end = block + num;
1901 			if (end >= next)
1902 				end = next;
1903 		} else if (block >= le32_to_cpu(ex->ee_block)) {
1904 			/*
1905 			 * some part of requested space is covered
1906 			 * by found extent
1907 			 */
1908 			start = block;
1909 			end = le32_to_cpu(ex->ee_block)
1910 				+ ext4_ext_get_actual_len(ex);
1911 			if (block + num < end)
1912 				end = block + num;
1913 			exists = 1;
1914 		} else {
1915 			BUG();
1916 		}
1917 		BUG_ON(end <= start);
1918 
1919 		if (!exists) {
1920 			cbex.ec_block = start;
1921 			cbex.ec_len = end - start;
1922 			cbex.ec_start = 0;
1923 		} else {
1924 			cbex.ec_block = le32_to_cpu(ex->ee_block);
1925 			cbex.ec_len = ext4_ext_get_actual_len(ex);
1926 			cbex.ec_start = ext4_ext_pblock(ex);
1927 		}
1928 
1929 		if (unlikely(cbex.ec_len == 0)) {
1930 			EXT4_ERROR_INODE(inode, "cbex.ec_len == 0");
1931 			err = -EIO;
1932 			break;
1933 		}
1934 		err = func(inode, next, &cbex, ex, cbdata);
1935 		ext4_ext_drop_refs(path);
1936 
1937 		if (err < 0)
1938 			break;
1939 
1940 		if (err == EXT_REPEAT)
1941 			continue;
1942 		else if (err == EXT_BREAK) {
1943 			err = 0;
1944 			break;
1945 		}
1946 
1947 		if (ext_depth(inode) != depth) {
1948 			/* depth was changed. we have to realloc path */
1949 			kfree(path);
1950 			path = NULL;
1951 		}
1952 
1953 		block = cbex.ec_block + cbex.ec_len;
1954 	}
1955 
1956 	if (path) {
1957 		ext4_ext_drop_refs(path);
1958 		kfree(path);
1959 	}
1960 
1961 	return err;
1962 }
1963 
1964 static void
1965 ext4_ext_put_in_cache(struct inode *inode, ext4_lblk_t block,
1966 			__u32 len, ext4_fsblk_t start)
1967 {
1968 	struct ext4_ext_cache *cex;
1969 	BUG_ON(len == 0);
1970 	spin_lock(&EXT4_I(inode)->i_block_reservation_lock);
1971 	trace_ext4_ext_put_in_cache(inode, block, len, start);
1972 	cex = &EXT4_I(inode)->i_cached_extent;
1973 	cex->ec_block = block;
1974 	cex->ec_len = len;
1975 	cex->ec_start = start;
1976 	spin_unlock(&EXT4_I(inode)->i_block_reservation_lock);
1977 }
1978 
1979 /*
1980  * ext4_ext_put_gap_in_cache:
1981  * calculate boundaries of the gap that the requested block fits into
1982  * and cache this gap
1983  */
1984 static void
1985 ext4_ext_put_gap_in_cache(struct inode *inode, struct ext4_ext_path *path,
1986 				ext4_lblk_t block)
1987 {
1988 	int depth = ext_depth(inode);
1989 	unsigned long len;
1990 	ext4_lblk_t lblock;
1991 	struct ext4_extent *ex;
1992 
1993 	ex = path[depth].p_ext;
1994 	if (ex == NULL) {
1995 		/* there is no extent yet, so gap is [0;-] */
1996 		lblock = 0;
1997 		len = EXT_MAX_BLOCKS;
1998 		ext_debug("cache gap(whole file):");
1999 	} else if (block < le32_to_cpu(ex->ee_block)) {
2000 		lblock = block;
2001 		len = le32_to_cpu(ex->ee_block) - block;
2002 		ext_debug("cache gap(before): %u [%u:%u]",
2003 				block,
2004 				le32_to_cpu(ex->ee_block),
2005 				 ext4_ext_get_actual_len(ex));
2006 	} else if (block >= le32_to_cpu(ex->ee_block)
2007 			+ ext4_ext_get_actual_len(ex)) {
2008 		ext4_lblk_t next;
2009 		lblock = le32_to_cpu(ex->ee_block)
2010 			+ ext4_ext_get_actual_len(ex);
2011 
2012 		next = ext4_ext_next_allocated_block(path);
2013 		ext_debug("cache gap(after): [%u:%u] %u",
2014 				le32_to_cpu(ex->ee_block),
2015 				ext4_ext_get_actual_len(ex),
2016 				block);
2017 		BUG_ON(next == lblock);
2018 		len = next - lblock;
2019 	} else {
2020 		lblock = len = 0;
2021 		BUG();
2022 	}
2023 
2024 	ext_debug(" -> %u:%lu\n", lblock, len);
2025 	ext4_ext_put_in_cache(inode, lblock, len, 0);
2026 }
2027 
2028 /*
2029  * ext4_ext_check_cache()
2030  * Checks to see if the given block is in the cache.
2031  * If it is, the cached extent is stored in the given
2032  * cache extent pointer.  If the cached extent is a hole,
2033  * this routine should be used instead of
2034  * ext4_ext_in_cache if the calling function needs to
2035  * know the size of the hole.
2036  *
2037  * @inode: The files inode
2038  * @block: The block to look for in the cache
2039  * @ex:    Pointer where the cached extent will be stored
2040  *         if it contains block
2041  *
2042  * Return 0 if cache is invalid; 1 if the cache is valid
2043  */
2044 static int ext4_ext_check_cache(struct inode *inode, ext4_lblk_t block,
2045 	struct ext4_ext_cache *ex){
2046 	struct ext4_ext_cache *cex;
2047 	struct ext4_sb_info *sbi;
2048 	int ret = 0;
2049 
2050 	/*
2051 	 * We borrow i_block_reservation_lock to protect i_cached_extent
2052 	 */
2053 	spin_lock(&EXT4_I(inode)->i_block_reservation_lock);
2054 	cex = &EXT4_I(inode)->i_cached_extent;
2055 	sbi = EXT4_SB(inode->i_sb);
2056 
2057 	/* has cache valid data? */
2058 	if (cex->ec_len == 0)
2059 		goto errout;
2060 
2061 	if (in_range(block, cex->ec_block, cex->ec_len)) {
2062 		memcpy(ex, cex, sizeof(struct ext4_ext_cache));
2063 		ext_debug("%u cached by %u:%u:%llu\n",
2064 				block,
2065 				cex->ec_block, cex->ec_len, cex->ec_start);
2066 		ret = 1;
2067 	}
2068 errout:
2069 	if (!ret)
2070 		sbi->extent_cache_misses++;
2071 	else
2072 		sbi->extent_cache_hits++;
2073 	trace_ext4_ext_in_cache(inode, block, ret);
2074 	spin_unlock(&EXT4_I(inode)->i_block_reservation_lock);
2075 	return ret;
2076 }
2077 
2078 /*
2079  * ext4_ext_in_cache()
2080  * Checks to see if the given block is in the cache.
2081  * If it is, the cached extent is stored in the given
2082  * extent pointer.
2083  *
2084  * @inode: The files inode
2085  * @block: The block to look for in the cache
2086  * @ex:    Pointer where the cached extent will be stored
2087  *         if it contains block
2088  *
2089  * Return 0 if cache is invalid; 1 if the cache is valid
2090  */
2091 static int
2092 ext4_ext_in_cache(struct inode *inode, ext4_lblk_t block,
2093 			struct ext4_extent *ex)
2094 {
2095 	struct ext4_ext_cache cex;
2096 	int ret = 0;
2097 
2098 	if (ext4_ext_check_cache(inode, block, &cex)) {
2099 		ex->ee_block = cpu_to_le32(cex.ec_block);
2100 		ext4_ext_store_pblock(ex, cex.ec_start);
2101 		ex->ee_len = cpu_to_le16(cex.ec_len);
2102 		ret = 1;
2103 	}
2104 
2105 	return ret;
2106 }
2107 
2108 
2109 /*
2110  * ext4_ext_rm_idx:
2111  * removes index from the index block.
2112  */
2113 static int ext4_ext_rm_idx(handle_t *handle, struct inode *inode,
2114 			struct ext4_ext_path *path)
2115 {
2116 	int err;
2117 	ext4_fsblk_t leaf;
2118 
2119 	/* free index block */
2120 	path--;
2121 	leaf = ext4_idx_pblock(path->p_idx);
2122 	if (unlikely(path->p_hdr->eh_entries == 0)) {
2123 		EXT4_ERROR_INODE(inode, "path->p_hdr->eh_entries == 0");
2124 		return -EIO;
2125 	}
2126 	err = ext4_ext_get_access(handle, inode, path);
2127 	if (err)
2128 		return err;
2129 
2130 	if (path->p_idx != EXT_LAST_INDEX(path->p_hdr)) {
2131 		int len = EXT_LAST_INDEX(path->p_hdr) - path->p_idx;
2132 		len *= sizeof(struct ext4_extent_idx);
2133 		memmove(path->p_idx, path->p_idx + 1, len);
2134 	}
2135 
2136 	le16_add_cpu(&path->p_hdr->eh_entries, -1);
2137 	err = ext4_ext_dirty(handle, inode, path);
2138 	if (err)
2139 		return err;
2140 	ext_debug("index is empty, remove it, free block %llu\n", leaf);
2141 	trace_ext4_ext_rm_idx(inode, leaf);
2142 
2143 	ext4_free_blocks(handle, inode, NULL, leaf, 1,
2144 			 EXT4_FREE_BLOCKS_METADATA | EXT4_FREE_BLOCKS_FORGET);
2145 	return err;
2146 }
2147 
2148 /*
2149  * ext4_ext_calc_credits_for_single_extent:
2150  * This routine returns max. credits that needed to insert an extent
2151  * to the extent tree.
2152  * When pass the actual path, the caller should calculate credits
2153  * under i_data_sem.
2154  */
2155 int ext4_ext_calc_credits_for_single_extent(struct inode *inode, int nrblocks,
2156 						struct ext4_ext_path *path)
2157 {
2158 	if (path) {
2159 		int depth = ext_depth(inode);
2160 		int ret = 0;
2161 
2162 		/* probably there is space in leaf? */
2163 		if (le16_to_cpu(path[depth].p_hdr->eh_entries)
2164 				< le16_to_cpu(path[depth].p_hdr->eh_max)) {
2165 
2166 			/*
2167 			 *  There are some space in the leaf tree, no
2168 			 *  need to account for leaf block credit
2169 			 *
2170 			 *  bitmaps and block group descriptor blocks
2171 			 *  and other metadata blocks still need to be
2172 			 *  accounted.
2173 			 */
2174 			/* 1 bitmap, 1 block group descriptor */
2175 			ret = 2 + EXT4_META_TRANS_BLOCKS(inode->i_sb);
2176 			return ret;
2177 		}
2178 	}
2179 
2180 	return ext4_chunk_trans_blocks(inode, nrblocks);
2181 }
2182 
2183 /*
2184  * How many index/leaf blocks need to change/allocate to modify nrblocks?
2185  *
2186  * if nrblocks are fit in a single extent (chunk flag is 1), then
2187  * in the worse case, each tree level index/leaf need to be changed
2188  * if the tree split due to insert a new extent, then the old tree
2189  * index/leaf need to be updated too
2190  *
2191  * If the nrblocks are discontiguous, they could cause
2192  * the whole tree split more than once, but this is really rare.
2193  */
2194 int ext4_ext_index_trans_blocks(struct inode *inode, int nrblocks, int chunk)
2195 {
2196 	int index;
2197 	int depth = ext_depth(inode);
2198 
2199 	if (chunk)
2200 		index = depth * 2;
2201 	else
2202 		index = depth * 3;
2203 
2204 	return index;
2205 }
2206 
2207 static int ext4_remove_blocks(handle_t *handle, struct inode *inode,
2208 			      struct ext4_extent *ex,
2209 			      ext4_fsblk_t *partial_cluster,
2210 			      ext4_lblk_t from, ext4_lblk_t to)
2211 {
2212 	struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
2213 	unsigned short ee_len =  ext4_ext_get_actual_len(ex);
2214 	ext4_fsblk_t pblk;
2215 	int flags = EXT4_FREE_BLOCKS_FORGET;
2216 
2217 	if (S_ISDIR(inode->i_mode) || S_ISLNK(inode->i_mode))
2218 		flags |= EXT4_FREE_BLOCKS_METADATA;
2219 	/*
2220 	 * For bigalloc file systems, we never free a partial cluster
2221 	 * at the beginning of the extent.  Instead, we make a note
2222 	 * that we tried freeing the cluster, and check to see if we
2223 	 * need to free it on a subsequent call to ext4_remove_blocks,
2224 	 * or at the end of the ext4_truncate() operation.
2225 	 */
2226 	flags |= EXT4_FREE_BLOCKS_NOFREE_FIRST_CLUSTER;
2227 
2228 	trace_ext4_remove_blocks(inode, ex, from, to, *partial_cluster);
2229 	/*
2230 	 * If we have a partial cluster, and it's different from the
2231 	 * cluster of the last block, we need to explicitly free the
2232 	 * partial cluster here.
2233 	 */
2234 	pblk = ext4_ext_pblock(ex) + ee_len - 1;
2235 	if (*partial_cluster && (EXT4_B2C(sbi, pblk) != *partial_cluster)) {
2236 		ext4_free_blocks(handle, inode, NULL,
2237 				 EXT4_C2B(sbi, *partial_cluster),
2238 				 sbi->s_cluster_ratio, flags);
2239 		*partial_cluster = 0;
2240 	}
2241 
2242 #ifdef EXTENTS_STATS
2243 	{
2244 		struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
2245 		spin_lock(&sbi->s_ext_stats_lock);
2246 		sbi->s_ext_blocks += ee_len;
2247 		sbi->s_ext_extents++;
2248 		if (ee_len < sbi->s_ext_min)
2249 			sbi->s_ext_min = ee_len;
2250 		if (ee_len > sbi->s_ext_max)
2251 			sbi->s_ext_max = ee_len;
2252 		if (ext_depth(inode) > sbi->s_depth_max)
2253 			sbi->s_depth_max = ext_depth(inode);
2254 		spin_unlock(&sbi->s_ext_stats_lock);
2255 	}
2256 #endif
2257 	if (from >= le32_to_cpu(ex->ee_block)
2258 	    && to == le32_to_cpu(ex->ee_block) + ee_len - 1) {
2259 		/* tail removal */
2260 		ext4_lblk_t num;
2261 
2262 		num = le32_to_cpu(ex->ee_block) + ee_len - from;
2263 		pblk = ext4_ext_pblock(ex) + ee_len - num;
2264 		ext_debug("free last %u blocks starting %llu\n", num, pblk);
2265 		ext4_free_blocks(handle, inode, NULL, pblk, num, flags);
2266 		/*
2267 		 * If the block range to be freed didn't start at the
2268 		 * beginning of a cluster, and we removed the entire
2269 		 * extent, save the partial cluster here, since we
2270 		 * might need to delete if we determine that the
2271 		 * truncate operation has removed all of the blocks in
2272 		 * the cluster.
2273 		 */
2274 		if (pblk & (sbi->s_cluster_ratio - 1) &&
2275 		    (ee_len == num))
2276 			*partial_cluster = EXT4_B2C(sbi, pblk);
2277 		else
2278 			*partial_cluster = 0;
2279 	} else if (from == le32_to_cpu(ex->ee_block)
2280 		   && to <= le32_to_cpu(ex->ee_block) + ee_len - 1) {
2281 		/* head removal */
2282 		ext4_lblk_t num;
2283 		ext4_fsblk_t start;
2284 
2285 		num = to - from;
2286 		start = ext4_ext_pblock(ex);
2287 
2288 		ext_debug("free first %u blocks starting %llu\n", num, start);
2289 		ext4_free_blocks(handle, inode, NULL, start, num, flags);
2290 
2291 	} else {
2292 		printk(KERN_INFO "strange request: removal(2) "
2293 				"%u-%u from %u:%u\n",
2294 				from, to, le32_to_cpu(ex->ee_block), ee_len);
2295 	}
2296 	return 0;
2297 }
2298 
2299 
2300 /*
2301  * ext4_ext_rm_leaf() Removes the extents associated with the
2302  * blocks appearing between "start" and "end", and splits the extents
2303  * if "start" and "end" appear in the same extent
2304  *
2305  * @handle: The journal handle
2306  * @inode:  The files inode
2307  * @path:   The path to the leaf
2308  * @start:  The first block to remove
2309  * @end:   The last block to remove
2310  */
2311 static int
2312 ext4_ext_rm_leaf(handle_t *handle, struct inode *inode,
2313 		 struct ext4_ext_path *path, ext4_fsblk_t *partial_cluster,
2314 		 ext4_lblk_t start, ext4_lblk_t end)
2315 {
2316 	struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
2317 	int err = 0, correct_index = 0;
2318 	int depth = ext_depth(inode), credits;
2319 	struct ext4_extent_header *eh;
2320 	ext4_lblk_t a, b;
2321 	unsigned num;
2322 	ext4_lblk_t ex_ee_block;
2323 	unsigned short ex_ee_len;
2324 	unsigned uninitialized = 0;
2325 	struct ext4_extent *ex;
2326 
2327 	/* the header must be checked already in ext4_ext_remove_space() */
2328 	ext_debug("truncate since %u in leaf to %u\n", start, end);
2329 	if (!path[depth].p_hdr)
2330 		path[depth].p_hdr = ext_block_hdr(path[depth].p_bh);
2331 	eh = path[depth].p_hdr;
2332 	if (unlikely(path[depth].p_hdr == NULL)) {
2333 		EXT4_ERROR_INODE(inode, "path[%d].p_hdr == NULL", depth);
2334 		return -EIO;
2335 	}
2336 	/* find where to start removing */
2337 	ex = EXT_LAST_EXTENT(eh);
2338 
2339 	ex_ee_block = le32_to_cpu(ex->ee_block);
2340 	ex_ee_len = ext4_ext_get_actual_len(ex);
2341 
2342 	trace_ext4_ext_rm_leaf(inode, start, ex, *partial_cluster);
2343 
2344 	while (ex >= EXT_FIRST_EXTENT(eh) &&
2345 			ex_ee_block + ex_ee_len > start) {
2346 
2347 		if (ext4_ext_is_uninitialized(ex))
2348 			uninitialized = 1;
2349 		else
2350 			uninitialized = 0;
2351 
2352 		ext_debug("remove ext %u:[%d]%d\n", ex_ee_block,
2353 			 uninitialized, ex_ee_len);
2354 		path[depth].p_ext = ex;
2355 
2356 		a = ex_ee_block > start ? ex_ee_block : start;
2357 		b = ex_ee_block+ex_ee_len - 1 < end ?
2358 			ex_ee_block+ex_ee_len - 1 : end;
2359 
2360 		ext_debug("  border %u:%u\n", a, b);
2361 
2362 		/* If this extent is beyond the end of the hole, skip it */
2363 		if (end < ex_ee_block) {
2364 			ex--;
2365 			ex_ee_block = le32_to_cpu(ex->ee_block);
2366 			ex_ee_len = ext4_ext_get_actual_len(ex);
2367 			continue;
2368 		} else if (b != ex_ee_block + ex_ee_len - 1) {
2369 			EXT4_ERROR_INODE(inode,"  bad truncate %u:%u\n",
2370 					 start, end);
2371 			err = -EIO;
2372 			goto out;
2373 		} else if (a != ex_ee_block) {
2374 			/* remove tail of the extent */
2375 			num = a - ex_ee_block;
2376 		} else {
2377 			/* remove whole extent: excellent! */
2378 			num = 0;
2379 		}
2380 		/*
2381 		 * 3 for leaf, sb, and inode plus 2 (bmap and group
2382 		 * descriptor) for each block group; assume two block
2383 		 * groups plus ex_ee_len/blocks_per_block_group for
2384 		 * the worst case
2385 		 */
2386 		credits = 7 + 2*(ex_ee_len/EXT4_BLOCKS_PER_GROUP(inode->i_sb));
2387 		if (ex == EXT_FIRST_EXTENT(eh)) {
2388 			correct_index = 1;
2389 			credits += (ext_depth(inode)) + 1;
2390 		}
2391 		credits += EXT4_MAXQUOTAS_TRANS_BLOCKS(inode->i_sb);
2392 
2393 		err = ext4_ext_truncate_extend_restart(handle, inode, credits);
2394 		if (err)
2395 			goto out;
2396 
2397 		err = ext4_ext_get_access(handle, inode, path + depth);
2398 		if (err)
2399 			goto out;
2400 
2401 		err = ext4_remove_blocks(handle, inode, ex, partial_cluster,
2402 					 a, b);
2403 		if (err)
2404 			goto out;
2405 
2406 		if (num == 0)
2407 			/* this extent is removed; mark slot entirely unused */
2408 			ext4_ext_store_pblock(ex, 0);
2409 
2410 		ex->ee_len = cpu_to_le16(num);
2411 		/*
2412 		 * Do not mark uninitialized if all the blocks in the
2413 		 * extent have been removed.
2414 		 */
2415 		if (uninitialized && num)
2416 			ext4_ext_mark_uninitialized(ex);
2417 		/*
2418 		 * If the extent was completely released,
2419 		 * we need to remove it from the leaf
2420 		 */
2421 		if (num == 0) {
2422 			if (end != EXT_MAX_BLOCKS - 1) {
2423 				/*
2424 				 * For hole punching, we need to scoot all the
2425 				 * extents up when an extent is removed so that
2426 				 * we dont have blank extents in the middle
2427 				 */
2428 				memmove(ex, ex+1, (EXT_LAST_EXTENT(eh) - ex) *
2429 					sizeof(struct ext4_extent));
2430 
2431 				/* Now get rid of the one at the end */
2432 				memset(EXT_LAST_EXTENT(eh), 0,
2433 					sizeof(struct ext4_extent));
2434 			}
2435 			le16_add_cpu(&eh->eh_entries, -1);
2436 		} else
2437 			*partial_cluster = 0;
2438 
2439 		err = ext4_ext_dirty(handle, inode, path + depth);
2440 		if (err)
2441 			goto out;
2442 
2443 		ext_debug("new extent: %u:%u:%llu\n", ex_ee_block, num,
2444 				ext4_ext_pblock(ex));
2445 		ex--;
2446 		ex_ee_block = le32_to_cpu(ex->ee_block);
2447 		ex_ee_len = ext4_ext_get_actual_len(ex);
2448 	}
2449 
2450 	if (correct_index && eh->eh_entries)
2451 		err = ext4_ext_correct_indexes(handle, inode, path);
2452 
2453 	/*
2454 	 * If there is still a entry in the leaf node, check to see if
2455 	 * it references the partial cluster.  This is the only place
2456 	 * where it could; if it doesn't, we can free the cluster.
2457 	 */
2458 	if (*partial_cluster && ex >= EXT_FIRST_EXTENT(eh) &&
2459 	    (EXT4_B2C(sbi, ext4_ext_pblock(ex) + ex_ee_len - 1) !=
2460 	     *partial_cluster)) {
2461 		int flags = EXT4_FREE_BLOCKS_FORGET;
2462 
2463 		if (S_ISDIR(inode->i_mode) || S_ISLNK(inode->i_mode))
2464 			flags |= EXT4_FREE_BLOCKS_METADATA;
2465 
2466 		ext4_free_blocks(handle, inode, NULL,
2467 				 EXT4_C2B(sbi, *partial_cluster),
2468 				 sbi->s_cluster_ratio, flags);
2469 		*partial_cluster = 0;
2470 	}
2471 
2472 	/* if this leaf is free, then we should
2473 	 * remove it from index block above */
2474 	if (err == 0 && eh->eh_entries == 0 && path[depth].p_bh != NULL)
2475 		err = ext4_ext_rm_idx(handle, inode, path + depth);
2476 
2477 out:
2478 	return err;
2479 }
2480 
2481 /*
2482  * ext4_ext_more_to_rm:
2483  * returns 1 if current index has to be freed (even partial)
2484  */
2485 static int
2486 ext4_ext_more_to_rm(struct ext4_ext_path *path)
2487 {
2488 	BUG_ON(path->p_idx == NULL);
2489 
2490 	if (path->p_idx < EXT_FIRST_INDEX(path->p_hdr))
2491 		return 0;
2492 
2493 	/*
2494 	 * if truncate on deeper level happened, it wasn't partial,
2495 	 * so we have to consider current index for truncation
2496 	 */
2497 	if (le16_to_cpu(path->p_hdr->eh_entries) == path->p_block)
2498 		return 0;
2499 	return 1;
2500 }
2501 
2502 static int ext4_ext_remove_space(struct inode *inode, ext4_lblk_t start,
2503 				 ext4_lblk_t end)
2504 {
2505 	struct super_block *sb = inode->i_sb;
2506 	int depth = ext_depth(inode);
2507 	struct ext4_ext_path *path;
2508 	ext4_fsblk_t partial_cluster = 0;
2509 	handle_t *handle;
2510 	int i, err;
2511 
2512 	ext_debug("truncate since %u to %u\n", start, end);
2513 
2514 	/* probably first extent we're gonna free will be last in block */
2515 	handle = ext4_journal_start(inode, depth + 1);
2516 	if (IS_ERR(handle))
2517 		return PTR_ERR(handle);
2518 
2519 again:
2520 	ext4_ext_invalidate_cache(inode);
2521 
2522 	trace_ext4_ext_remove_space(inode, start, depth);
2523 
2524 	/*
2525 	 * Check if we are removing extents inside the extent tree. If that
2526 	 * is the case, we are going to punch a hole inside the extent tree
2527 	 * so we have to check whether we need to split the extent covering
2528 	 * the last block to remove so we can easily remove the part of it
2529 	 * in ext4_ext_rm_leaf().
2530 	 */
2531 	if (end < EXT_MAX_BLOCKS - 1) {
2532 		struct ext4_extent *ex;
2533 		ext4_lblk_t ee_block;
2534 
2535 		/* find extent for this block */
2536 		path = ext4_ext_find_extent(inode, end, NULL);
2537 		if (IS_ERR(path)) {
2538 			ext4_journal_stop(handle);
2539 			return PTR_ERR(path);
2540 		}
2541 		depth = ext_depth(inode);
2542 		ex = path[depth].p_ext;
2543 		if (!ex)
2544 			goto cont;
2545 
2546 		ee_block = le32_to_cpu(ex->ee_block);
2547 
2548 		/*
2549 		 * See if the last block is inside the extent, if so split
2550 		 * the extent at 'end' block so we can easily remove the
2551 		 * tail of the first part of the split extent in
2552 		 * ext4_ext_rm_leaf().
2553 		 */
2554 		if (end >= ee_block &&
2555 		    end < ee_block + ext4_ext_get_actual_len(ex) - 1) {
2556 			int split_flag = 0;
2557 
2558 			if (ext4_ext_is_uninitialized(ex))
2559 				split_flag = EXT4_EXT_MARK_UNINIT1 |
2560 					     EXT4_EXT_MARK_UNINIT2;
2561 
2562 			/*
2563 			 * Split the extent in two so that 'end' is the last
2564 			 * block in the first new extent
2565 			 */
2566 			err = ext4_split_extent_at(handle, inode, path,
2567 						end + 1, split_flag,
2568 						EXT4_GET_BLOCKS_PRE_IO |
2569 						EXT4_GET_BLOCKS_PUNCH_OUT_EXT);
2570 
2571 			if (err < 0)
2572 				goto out;
2573 		}
2574 		ext4_ext_drop_refs(path);
2575 		kfree(path);
2576 	}
2577 cont:
2578 
2579 	/*
2580 	 * We start scanning from right side, freeing all the blocks
2581 	 * after i_size and walking into the tree depth-wise.
2582 	 */
2583 	depth = ext_depth(inode);
2584 	path = kzalloc(sizeof(struct ext4_ext_path) * (depth + 1), GFP_NOFS);
2585 	if (path == NULL) {
2586 		ext4_journal_stop(handle);
2587 		return -ENOMEM;
2588 	}
2589 	path[0].p_depth = depth;
2590 	path[0].p_hdr = ext_inode_hdr(inode);
2591 
2592 	if (ext4_ext_check(inode, path[0].p_hdr, depth)) {
2593 		err = -EIO;
2594 		goto out;
2595 	}
2596 	i = err = 0;
2597 
2598 	while (i >= 0 && err == 0) {
2599 		if (i == depth) {
2600 			/* this is leaf block */
2601 			err = ext4_ext_rm_leaf(handle, inode, path,
2602 					       &partial_cluster, start,
2603 					       end);
2604 			/* root level has p_bh == NULL, brelse() eats this */
2605 			brelse(path[i].p_bh);
2606 			path[i].p_bh = NULL;
2607 			i--;
2608 			continue;
2609 		}
2610 
2611 		/* this is index block */
2612 		if (!path[i].p_hdr) {
2613 			ext_debug("initialize header\n");
2614 			path[i].p_hdr = ext_block_hdr(path[i].p_bh);
2615 		}
2616 
2617 		if (!path[i].p_idx) {
2618 			/* this level hasn't been touched yet */
2619 			path[i].p_idx = EXT_LAST_INDEX(path[i].p_hdr);
2620 			path[i].p_block = le16_to_cpu(path[i].p_hdr->eh_entries)+1;
2621 			ext_debug("init index ptr: hdr 0x%p, num %d\n",
2622 				  path[i].p_hdr,
2623 				  le16_to_cpu(path[i].p_hdr->eh_entries));
2624 		} else {
2625 			/* we were already here, see at next index */
2626 			path[i].p_idx--;
2627 		}
2628 
2629 		ext_debug("level %d - index, first 0x%p, cur 0x%p\n",
2630 				i, EXT_FIRST_INDEX(path[i].p_hdr),
2631 				path[i].p_idx);
2632 		if (ext4_ext_more_to_rm(path + i)) {
2633 			struct buffer_head *bh;
2634 			/* go to the next level */
2635 			ext_debug("move to level %d (block %llu)\n",
2636 				  i + 1, ext4_idx_pblock(path[i].p_idx));
2637 			memset(path + i + 1, 0, sizeof(*path));
2638 			bh = sb_bread(sb, ext4_idx_pblock(path[i].p_idx));
2639 			if (!bh) {
2640 				/* should we reset i_size? */
2641 				err = -EIO;
2642 				break;
2643 			}
2644 			if (WARN_ON(i + 1 > depth)) {
2645 				err = -EIO;
2646 				break;
2647 			}
2648 			if (ext4_ext_check(inode, ext_block_hdr(bh),
2649 							depth - i - 1)) {
2650 				err = -EIO;
2651 				break;
2652 			}
2653 			path[i + 1].p_bh = bh;
2654 
2655 			/* save actual number of indexes since this
2656 			 * number is changed at the next iteration */
2657 			path[i].p_block = le16_to_cpu(path[i].p_hdr->eh_entries);
2658 			i++;
2659 		} else {
2660 			/* we finished processing this index, go up */
2661 			if (path[i].p_hdr->eh_entries == 0 && i > 0) {
2662 				/* index is empty, remove it;
2663 				 * handle must be already prepared by the
2664 				 * truncatei_leaf() */
2665 				err = ext4_ext_rm_idx(handle, inode, path + i);
2666 			}
2667 			/* root level has p_bh == NULL, brelse() eats this */
2668 			brelse(path[i].p_bh);
2669 			path[i].p_bh = NULL;
2670 			i--;
2671 			ext_debug("return to level %d\n", i);
2672 		}
2673 	}
2674 
2675 	trace_ext4_ext_remove_space_done(inode, start, depth, partial_cluster,
2676 			path->p_hdr->eh_entries);
2677 
2678 	/* If we still have something in the partial cluster and we have removed
2679 	 * even the first extent, then we should free the blocks in the partial
2680 	 * cluster as well. */
2681 	if (partial_cluster && path->p_hdr->eh_entries == 0) {
2682 		int flags = EXT4_FREE_BLOCKS_FORGET;
2683 
2684 		if (S_ISDIR(inode->i_mode) || S_ISLNK(inode->i_mode))
2685 			flags |= EXT4_FREE_BLOCKS_METADATA;
2686 
2687 		ext4_free_blocks(handle, inode, NULL,
2688 				 EXT4_C2B(EXT4_SB(sb), partial_cluster),
2689 				 EXT4_SB(sb)->s_cluster_ratio, flags);
2690 		partial_cluster = 0;
2691 	}
2692 
2693 	/* TODO: flexible tree reduction should be here */
2694 	if (path->p_hdr->eh_entries == 0) {
2695 		/*
2696 		 * truncate to zero freed all the tree,
2697 		 * so we need to correct eh_depth
2698 		 */
2699 		err = ext4_ext_get_access(handle, inode, path);
2700 		if (err == 0) {
2701 			ext_inode_hdr(inode)->eh_depth = 0;
2702 			ext_inode_hdr(inode)->eh_max =
2703 				cpu_to_le16(ext4_ext_space_root(inode, 0));
2704 			err = ext4_ext_dirty(handle, inode, path);
2705 		}
2706 	}
2707 out:
2708 	ext4_ext_drop_refs(path);
2709 	kfree(path);
2710 	if (err == -EAGAIN)
2711 		goto again;
2712 	ext4_journal_stop(handle);
2713 
2714 	return err;
2715 }
2716 
2717 /*
2718  * called at mount time
2719  */
2720 void ext4_ext_init(struct super_block *sb)
2721 {
2722 	/*
2723 	 * possible initialization would be here
2724 	 */
2725 
2726 	if (EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_EXTENTS)) {
2727 #if defined(AGGRESSIVE_TEST) || defined(CHECK_BINSEARCH) || defined(EXTENTS_STATS)
2728 		printk(KERN_INFO "EXT4-fs: file extents enabled");
2729 #ifdef AGGRESSIVE_TEST
2730 		printk(", aggressive tests");
2731 #endif
2732 #ifdef CHECK_BINSEARCH
2733 		printk(", check binsearch");
2734 #endif
2735 #ifdef EXTENTS_STATS
2736 		printk(", stats");
2737 #endif
2738 		printk("\n");
2739 #endif
2740 #ifdef EXTENTS_STATS
2741 		spin_lock_init(&EXT4_SB(sb)->s_ext_stats_lock);
2742 		EXT4_SB(sb)->s_ext_min = 1 << 30;
2743 		EXT4_SB(sb)->s_ext_max = 0;
2744 #endif
2745 	}
2746 }
2747 
2748 /*
2749  * called at umount time
2750  */
2751 void ext4_ext_release(struct super_block *sb)
2752 {
2753 	if (!EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_EXTENTS))
2754 		return;
2755 
2756 #ifdef EXTENTS_STATS
2757 	if (EXT4_SB(sb)->s_ext_blocks && EXT4_SB(sb)->s_ext_extents) {
2758 		struct ext4_sb_info *sbi = EXT4_SB(sb);
2759 		printk(KERN_ERR "EXT4-fs: %lu blocks in %lu extents (%lu ave)\n",
2760 			sbi->s_ext_blocks, sbi->s_ext_extents,
2761 			sbi->s_ext_blocks / sbi->s_ext_extents);
2762 		printk(KERN_ERR "EXT4-fs: extents: %lu min, %lu max, max depth %lu\n",
2763 			sbi->s_ext_min, sbi->s_ext_max, sbi->s_depth_max);
2764 	}
2765 #endif
2766 }
2767 
2768 /* FIXME!! we need to try to merge to left or right after zero-out  */
2769 static int ext4_ext_zeroout(struct inode *inode, struct ext4_extent *ex)
2770 {
2771 	ext4_fsblk_t ee_pblock;
2772 	unsigned int ee_len;
2773 	int ret;
2774 
2775 	ee_len    = ext4_ext_get_actual_len(ex);
2776 	ee_pblock = ext4_ext_pblock(ex);
2777 
2778 	ret = sb_issue_zeroout(inode->i_sb, ee_pblock, ee_len, GFP_NOFS);
2779 	if (ret > 0)
2780 		ret = 0;
2781 
2782 	return ret;
2783 }
2784 
2785 /*
2786  * ext4_split_extent_at() splits an extent at given block.
2787  *
2788  * @handle: the journal handle
2789  * @inode: the file inode
2790  * @path: the path to the extent
2791  * @split: the logical block where the extent is splitted.
2792  * @split_flags: indicates if the extent could be zeroout if split fails, and
2793  *		 the states(init or uninit) of new extents.
2794  * @flags: flags used to insert new extent to extent tree.
2795  *
2796  *
2797  * Splits extent [a, b] into two extents [a, @split) and [@split, b], states
2798  * of which are deterimined by split_flag.
2799  *
2800  * There are two cases:
2801  *  a> the extent are splitted into two extent.
2802  *  b> split is not needed, and just mark the extent.
2803  *
2804  * return 0 on success.
2805  */
2806 static int ext4_split_extent_at(handle_t *handle,
2807 			     struct inode *inode,
2808 			     struct ext4_ext_path *path,
2809 			     ext4_lblk_t split,
2810 			     int split_flag,
2811 			     int flags)
2812 {
2813 	ext4_fsblk_t newblock;
2814 	ext4_lblk_t ee_block;
2815 	struct ext4_extent *ex, newex, orig_ex;
2816 	struct ext4_extent *ex2 = NULL;
2817 	unsigned int ee_len, depth;
2818 	int err = 0;
2819 
2820 	ext_debug("ext4_split_extents_at: inode %lu, logical"
2821 		"block %llu\n", inode->i_ino, (unsigned long long)split);
2822 
2823 	ext4_ext_show_leaf(inode, path);
2824 
2825 	depth = ext_depth(inode);
2826 	ex = path[depth].p_ext;
2827 	ee_block = le32_to_cpu(ex->ee_block);
2828 	ee_len = ext4_ext_get_actual_len(ex);
2829 	newblock = split - ee_block + ext4_ext_pblock(ex);
2830 
2831 	BUG_ON(split < ee_block || split >= (ee_block + ee_len));
2832 
2833 	err = ext4_ext_get_access(handle, inode, path + depth);
2834 	if (err)
2835 		goto out;
2836 
2837 	if (split == ee_block) {
2838 		/*
2839 		 * case b: block @split is the block that the extent begins with
2840 		 * then we just change the state of the extent, and splitting
2841 		 * is not needed.
2842 		 */
2843 		if (split_flag & EXT4_EXT_MARK_UNINIT2)
2844 			ext4_ext_mark_uninitialized(ex);
2845 		else
2846 			ext4_ext_mark_initialized(ex);
2847 
2848 		if (!(flags & EXT4_GET_BLOCKS_PRE_IO))
2849 			ext4_ext_try_to_merge(inode, path, ex);
2850 
2851 		err = ext4_ext_dirty(handle, inode, path + depth);
2852 		goto out;
2853 	}
2854 
2855 	/* case a */
2856 	memcpy(&orig_ex, ex, sizeof(orig_ex));
2857 	ex->ee_len = cpu_to_le16(split - ee_block);
2858 	if (split_flag & EXT4_EXT_MARK_UNINIT1)
2859 		ext4_ext_mark_uninitialized(ex);
2860 
2861 	/*
2862 	 * path may lead to new leaf, not to original leaf any more
2863 	 * after ext4_ext_insert_extent() returns,
2864 	 */
2865 	err = ext4_ext_dirty(handle, inode, path + depth);
2866 	if (err)
2867 		goto fix_extent_len;
2868 
2869 	ex2 = &newex;
2870 	ex2->ee_block = cpu_to_le32(split);
2871 	ex2->ee_len   = cpu_to_le16(ee_len - (split - ee_block));
2872 	ext4_ext_store_pblock(ex2, newblock);
2873 	if (split_flag & EXT4_EXT_MARK_UNINIT2)
2874 		ext4_ext_mark_uninitialized(ex2);
2875 
2876 	err = ext4_ext_insert_extent(handle, inode, path, &newex, flags);
2877 	if (err == -ENOSPC && (EXT4_EXT_MAY_ZEROOUT & split_flag)) {
2878 		err = ext4_ext_zeroout(inode, &orig_ex);
2879 		if (err)
2880 			goto fix_extent_len;
2881 		/* update the extent length and mark as initialized */
2882 		ex->ee_len = cpu_to_le32(ee_len);
2883 		ext4_ext_try_to_merge(inode, path, ex);
2884 		err = ext4_ext_dirty(handle, inode, path + depth);
2885 		goto out;
2886 	} else if (err)
2887 		goto fix_extent_len;
2888 
2889 out:
2890 	ext4_ext_show_leaf(inode, path);
2891 	return err;
2892 
2893 fix_extent_len:
2894 	ex->ee_len = orig_ex.ee_len;
2895 	ext4_ext_dirty(handle, inode, path + depth);
2896 	return err;
2897 }
2898 
2899 /*
2900  * ext4_split_extents() splits an extent and mark extent which is covered
2901  * by @map as split_flags indicates
2902  *
2903  * It may result in splitting the extent into multiple extents (upto three)
2904  * There are three possibilities:
2905  *   a> There is no split required
2906  *   b> Splits in two extents: Split is happening at either end of the extent
2907  *   c> Splits in three extents: Somone is splitting in middle of the extent
2908  *
2909  */
2910 static int ext4_split_extent(handle_t *handle,
2911 			      struct inode *inode,
2912 			      struct ext4_ext_path *path,
2913 			      struct ext4_map_blocks *map,
2914 			      int split_flag,
2915 			      int flags)
2916 {
2917 	ext4_lblk_t ee_block;
2918 	struct ext4_extent *ex;
2919 	unsigned int ee_len, depth;
2920 	int err = 0;
2921 	int uninitialized;
2922 	int split_flag1, flags1;
2923 
2924 	depth = ext_depth(inode);
2925 	ex = path[depth].p_ext;
2926 	ee_block = le32_to_cpu(ex->ee_block);
2927 	ee_len = ext4_ext_get_actual_len(ex);
2928 	uninitialized = ext4_ext_is_uninitialized(ex);
2929 
2930 	if (map->m_lblk + map->m_len < ee_block + ee_len) {
2931 		split_flag1 = split_flag & EXT4_EXT_MAY_ZEROOUT ?
2932 			      EXT4_EXT_MAY_ZEROOUT : 0;
2933 		flags1 = flags | EXT4_GET_BLOCKS_PRE_IO;
2934 		if (uninitialized)
2935 			split_flag1 |= EXT4_EXT_MARK_UNINIT1 |
2936 				       EXT4_EXT_MARK_UNINIT2;
2937 		err = ext4_split_extent_at(handle, inode, path,
2938 				map->m_lblk + map->m_len, split_flag1, flags1);
2939 		if (err)
2940 			goto out;
2941 	}
2942 
2943 	ext4_ext_drop_refs(path);
2944 	path = ext4_ext_find_extent(inode, map->m_lblk, path);
2945 	if (IS_ERR(path))
2946 		return PTR_ERR(path);
2947 
2948 	if (map->m_lblk >= ee_block) {
2949 		split_flag1 = split_flag & EXT4_EXT_MAY_ZEROOUT ?
2950 			      EXT4_EXT_MAY_ZEROOUT : 0;
2951 		if (uninitialized)
2952 			split_flag1 |= EXT4_EXT_MARK_UNINIT1;
2953 		if (split_flag & EXT4_EXT_MARK_UNINIT2)
2954 			split_flag1 |= EXT4_EXT_MARK_UNINIT2;
2955 		err = ext4_split_extent_at(handle, inode, path,
2956 				map->m_lblk, split_flag1, flags);
2957 		if (err)
2958 			goto out;
2959 	}
2960 
2961 	ext4_ext_show_leaf(inode, path);
2962 out:
2963 	return err ? err : map->m_len;
2964 }
2965 
2966 #define EXT4_EXT_ZERO_LEN 7
2967 /*
2968  * This function is called by ext4_ext_map_blocks() if someone tries to write
2969  * to an uninitialized extent. It may result in splitting the uninitialized
2970  * extent into multiple extents (up to three - one initialized and two
2971  * uninitialized).
2972  * There are three possibilities:
2973  *   a> There is no split required: Entire extent should be initialized
2974  *   b> Splits in two extents: Write is happening at either end of the extent
2975  *   c> Splits in three extents: Somone is writing in middle of the extent
2976  *
2977  * Pre-conditions:
2978  *  - The extent pointed to by 'path' is uninitialized.
2979  *  - The extent pointed to by 'path' contains a superset
2980  *    of the logical span [map->m_lblk, map->m_lblk + map->m_len).
2981  *
2982  * Post-conditions on success:
2983  *  - the returned value is the number of blocks beyond map->l_lblk
2984  *    that are allocated and initialized.
2985  *    It is guaranteed to be >= map->m_len.
2986  */
2987 static int ext4_ext_convert_to_initialized(handle_t *handle,
2988 					   struct inode *inode,
2989 					   struct ext4_map_blocks *map,
2990 					   struct ext4_ext_path *path)
2991 {
2992 	struct ext4_extent_header *eh;
2993 	struct ext4_map_blocks split_map;
2994 	struct ext4_extent zero_ex;
2995 	struct ext4_extent *ex;
2996 	ext4_lblk_t ee_block, eof_block;
2997 	unsigned int ee_len, depth;
2998 	int allocated;
2999 	int err = 0;
3000 	int split_flag = 0;
3001 
3002 	ext_debug("ext4_ext_convert_to_initialized: inode %lu, logical"
3003 		"block %llu, max_blocks %u\n", inode->i_ino,
3004 		(unsigned long long)map->m_lblk, map->m_len);
3005 
3006 	eof_block = (inode->i_size + inode->i_sb->s_blocksize - 1) >>
3007 		inode->i_sb->s_blocksize_bits;
3008 	if (eof_block < map->m_lblk + map->m_len)
3009 		eof_block = map->m_lblk + map->m_len;
3010 
3011 	depth = ext_depth(inode);
3012 	eh = path[depth].p_hdr;
3013 	ex = path[depth].p_ext;
3014 	ee_block = le32_to_cpu(ex->ee_block);
3015 	ee_len = ext4_ext_get_actual_len(ex);
3016 	allocated = ee_len - (map->m_lblk - ee_block);
3017 
3018 	trace_ext4_ext_convert_to_initialized_enter(inode, map, ex);
3019 
3020 	/* Pre-conditions */
3021 	BUG_ON(!ext4_ext_is_uninitialized(ex));
3022 	BUG_ON(!in_range(map->m_lblk, ee_block, ee_len));
3023 
3024 	/*
3025 	 * Attempt to transfer newly initialized blocks from the currently
3026 	 * uninitialized extent to its left neighbor. This is much cheaper
3027 	 * than an insertion followed by a merge as those involve costly
3028 	 * memmove() calls. This is the common case in steady state for
3029 	 * workloads doing fallocate(FALLOC_FL_KEEP_SIZE) followed by append
3030 	 * writes.
3031 	 *
3032 	 * Limitations of the current logic:
3033 	 *  - L1: we only deal with writes at the start of the extent.
3034 	 *    The approach could be extended to writes at the end
3035 	 *    of the extent but this scenario was deemed less common.
3036 	 *  - L2: we do not deal with writes covering the whole extent.
3037 	 *    This would require removing the extent if the transfer
3038 	 *    is possible.
3039 	 *  - L3: we only attempt to merge with an extent stored in the
3040 	 *    same extent tree node.
3041 	 */
3042 	if ((map->m_lblk == ee_block) &&	/*L1*/
3043 		(map->m_len < ee_len) &&	/*L2*/
3044 		(ex > EXT_FIRST_EXTENT(eh))) {	/*L3*/
3045 		struct ext4_extent *prev_ex;
3046 		ext4_lblk_t prev_lblk;
3047 		ext4_fsblk_t prev_pblk, ee_pblk;
3048 		unsigned int prev_len, write_len;
3049 
3050 		prev_ex = ex - 1;
3051 		prev_lblk = le32_to_cpu(prev_ex->ee_block);
3052 		prev_len = ext4_ext_get_actual_len(prev_ex);
3053 		prev_pblk = ext4_ext_pblock(prev_ex);
3054 		ee_pblk = ext4_ext_pblock(ex);
3055 		write_len = map->m_len;
3056 
3057 		/*
3058 		 * A transfer of blocks from 'ex' to 'prev_ex' is allowed
3059 		 * upon those conditions:
3060 		 * - C1: prev_ex is initialized,
3061 		 * - C2: prev_ex is logically abutting ex,
3062 		 * - C3: prev_ex is physically abutting ex,
3063 		 * - C4: prev_ex can receive the additional blocks without
3064 		 *   overflowing the (initialized) length limit.
3065 		 */
3066 		if ((!ext4_ext_is_uninitialized(prev_ex)) &&		/*C1*/
3067 			((prev_lblk + prev_len) == ee_block) &&		/*C2*/
3068 			((prev_pblk + prev_len) == ee_pblk) &&		/*C3*/
3069 			(prev_len < (EXT_INIT_MAX_LEN - write_len))) {	/*C4*/
3070 			err = ext4_ext_get_access(handle, inode, path + depth);
3071 			if (err)
3072 				goto out;
3073 
3074 			trace_ext4_ext_convert_to_initialized_fastpath(inode,
3075 				map, ex, prev_ex);
3076 
3077 			/* Shift the start of ex by 'write_len' blocks */
3078 			ex->ee_block = cpu_to_le32(ee_block + write_len);
3079 			ext4_ext_store_pblock(ex, ee_pblk + write_len);
3080 			ex->ee_len = cpu_to_le16(ee_len - write_len);
3081 			ext4_ext_mark_uninitialized(ex); /* Restore the flag */
3082 
3083 			/* Extend prev_ex by 'write_len' blocks */
3084 			prev_ex->ee_len = cpu_to_le16(prev_len + write_len);
3085 
3086 			/* Mark the block containing both extents as dirty */
3087 			ext4_ext_dirty(handle, inode, path + depth);
3088 
3089 			/* Update path to point to the right extent */
3090 			path[depth].p_ext = prev_ex;
3091 
3092 			/* Result: number of initialized blocks past m_lblk */
3093 			allocated = write_len;
3094 			goto out;
3095 		}
3096 	}
3097 
3098 	WARN_ON(map->m_lblk < ee_block);
3099 	/*
3100 	 * It is safe to convert extent to initialized via explicit
3101 	 * zeroout only if extent is fully insde i_size or new_size.
3102 	 */
3103 	split_flag |= ee_block + ee_len <= eof_block ? EXT4_EXT_MAY_ZEROOUT : 0;
3104 
3105 	/* If extent has less than 2*EXT4_EXT_ZERO_LEN zerout directly */
3106 	if (ee_len <= 2*EXT4_EXT_ZERO_LEN &&
3107 	    (EXT4_EXT_MAY_ZEROOUT & split_flag)) {
3108 		err = ext4_ext_zeroout(inode, ex);
3109 		if (err)
3110 			goto out;
3111 
3112 		err = ext4_ext_get_access(handle, inode, path + depth);
3113 		if (err)
3114 			goto out;
3115 		ext4_ext_mark_initialized(ex);
3116 		ext4_ext_try_to_merge(inode, path, ex);
3117 		err = ext4_ext_dirty(handle, inode, path + depth);
3118 		goto out;
3119 	}
3120 
3121 	/*
3122 	 * four cases:
3123 	 * 1. split the extent into three extents.
3124 	 * 2. split the extent into two extents, zeroout the first half.
3125 	 * 3. split the extent into two extents, zeroout the second half.
3126 	 * 4. split the extent into two extents with out zeroout.
3127 	 */
3128 	split_map.m_lblk = map->m_lblk;
3129 	split_map.m_len = map->m_len;
3130 
3131 	if (allocated > map->m_len) {
3132 		if (allocated <= EXT4_EXT_ZERO_LEN &&
3133 		    (EXT4_EXT_MAY_ZEROOUT & split_flag)) {
3134 			/* case 3 */
3135 			zero_ex.ee_block =
3136 					 cpu_to_le32(map->m_lblk);
3137 			zero_ex.ee_len = cpu_to_le16(allocated);
3138 			ext4_ext_store_pblock(&zero_ex,
3139 				ext4_ext_pblock(ex) + map->m_lblk - ee_block);
3140 			err = ext4_ext_zeroout(inode, &zero_ex);
3141 			if (err)
3142 				goto out;
3143 			split_map.m_lblk = map->m_lblk;
3144 			split_map.m_len = allocated;
3145 		} else if ((map->m_lblk - ee_block + map->m_len <
3146 			   EXT4_EXT_ZERO_LEN) &&
3147 			   (EXT4_EXT_MAY_ZEROOUT & split_flag)) {
3148 			/* case 2 */
3149 			if (map->m_lblk != ee_block) {
3150 				zero_ex.ee_block = ex->ee_block;
3151 				zero_ex.ee_len = cpu_to_le16(map->m_lblk -
3152 							ee_block);
3153 				ext4_ext_store_pblock(&zero_ex,
3154 						      ext4_ext_pblock(ex));
3155 				err = ext4_ext_zeroout(inode, &zero_ex);
3156 				if (err)
3157 					goto out;
3158 			}
3159 
3160 			split_map.m_lblk = ee_block;
3161 			split_map.m_len = map->m_lblk - ee_block + map->m_len;
3162 			allocated = map->m_len;
3163 		}
3164 	}
3165 
3166 	allocated = ext4_split_extent(handle, inode, path,
3167 				       &split_map, split_flag, 0);
3168 	if (allocated < 0)
3169 		err = allocated;
3170 
3171 out:
3172 	return err ? err : allocated;
3173 }
3174 
3175 /*
3176  * This function is called by ext4_ext_map_blocks() from
3177  * ext4_get_blocks_dio_write() when DIO to write
3178  * to an uninitialized extent.
3179  *
3180  * Writing to an uninitialized extent may result in splitting the uninitialized
3181  * extent into multiple /initialized uninitialized extents (up to three)
3182  * There are three possibilities:
3183  *   a> There is no split required: Entire extent should be uninitialized
3184  *   b> Splits in two extents: Write is happening at either end of the extent
3185  *   c> Splits in three extents: Somone is writing in middle of the extent
3186  *
3187  * One of more index blocks maybe needed if the extent tree grow after
3188  * the uninitialized extent split. To prevent ENOSPC occur at the IO
3189  * complete, we need to split the uninitialized extent before DIO submit
3190  * the IO. The uninitialized extent called at this time will be split
3191  * into three uninitialized extent(at most). After IO complete, the part
3192  * being filled will be convert to initialized by the end_io callback function
3193  * via ext4_convert_unwritten_extents().
3194  *
3195  * Returns the size of uninitialized extent to be written on success.
3196  */
3197 static int ext4_split_unwritten_extents(handle_t *handle,
3198 					struct inode *inode,
3199 					struct ext4_map_blocks *map,
3200 					struct ext4_ext_path *path,
3201 					int flags)
3202 {
3203 	ext4_lblk_t eof_block;
3204 	ext4_lblk_t ee_block;
3205 	struct ext4_extent *ex;
3206 	unsigned int ee_len;
3207 	int split_flag = 0, depth;
3208 
3209 	ext_debug("ext4_split_unwritten_extents: inode %lu, logical"
3210 		"block %llu, max_blocks %u\n", inode->i_ino,
3211 		(unsigned long long)map->m_lblk, map->m_len);
3212 
3213 	eof_block = (inode->i_size + inode->i_sb->s_blocksize - 1) >>
3214 		inode->i_sb->s_blocksize_bits;
3215 	if (eof_block < map->m_lblk + map->m_len)
3216 		eof_block = map->m_lblk + map->m_len;
3217 	/*
3218 	 * It is safe to convert extent to initialized via explicit
3219 	 * zeroout only if extent is fully insde i_size or new_size.
3220 	 */
3221 	depth = ext_depth(inode);
3222 	ex = path[depth].p_ext;
3223 	ee_block = le32_to_cpu(ex->ee_block);
3224 	ee_len = ext4_ext_get_actual_len(ex);
3225 
3226 	split_flag |= ee_block + ee_len <= eof_block ? EXT4_EXT_MAY_ZEROOUT : 0;
3227 	split_flag |= EXT4_EXT_MARK_UNINIT2;
3228 
3229 	flags |= EXT4_GET_BLOCKS_PRE_IO;
3230 	return ext4_split_extent(handle, inode, path, map, split_flag, flags);
3231 }
3232 
3233 static int ext4_convert_unwritten_extents_endio(handle_t *handle,
3234 					      struct inode *inode,
3235 					      struct ext4_ext_path *path)
3236 {
3237 	struct ext4_extent *ex;
3238 	int depth;
3239 	int err = 0;
3240 
3241 	depth = ext_depth(inode);
3242 	ex = path[depth].p_ext;
3243 
3244 	ext_debug("ext4_convert_unwritten_extents_endio: inode %lu, logical"
3245 		"block %llu, max_blocks %u\n", inode->i_ino,
3246 		(unsigned long long)le32_to_cpu(ex->ee_block),
3247 		ext4_ext_get_actual_len(ex));
3248 
3249 	err = ext4_ext_get_access(handle, inode, path + depth);
3250 	if (err)
3251 		goto out;
3252 	/* first mark the extent as initialized */
3253 	ext4_ext_mark_initialized(ex);
3254 
3255 	/* note: ext4_ext_correct_indexes() isn't needed here because
3256 	 * borders are not changed
3257 	 */
3258 	ext4_ext_try_to_merge(inode, path, ex);
3259 
3260 	/* Mark modified extent as dirty */
3261 	err = ext4_ext_dirty(handle, inode, path + depth);
3262 out:
3263 	ext4_ext_show_leaf(inode, path);
3264 	return err;
3265 }
3266 
3267 static void unmap_underlying_metadata_blocks(struct block_device *bdev,
3268 			sector_t block, int count)
3269 {
3270 	int i;
3271 	for (i = 0; i < count; i++)
3272                 unmap_underlying_metadata(bdev, block + i);
3273 }
3274 
3275 /*
3276  * Handle EOFBLOCKS_FL flag, clearing it if necessary
3277  */
3278 static int check_eofblocks_fl(handle_t *handle, struct inode *inode,
3279 			      ext4_lblk_t lblk,
3280 			      struct ext4_ext_path *path,
3281 			      unsigned int len)
3282 {
3283 	int i, depth;
3284 	struct ext4_extent_header *eh;
3285 	struct ext4_extent *last_ex;
3286 
3287 	if (!ext4_test_inode_flag(inode, EXT4_INODE_EOFBLOCKS))
3288 		return 0;
3289 
3290 	depth = ext_depth(inode);
3291 	eh = path[depth].p_hdr;
3292 
3293 	if (unlikely(!eh->eh_entries)) {
3294 		EXT4_ERROR_INODE(inode, "eh->eh_entries == 0 and "
3295 				 "EOFBLOCKS_FL set");
3296 		return -EIO;
3297 	}
3298 	last_ex = EXT_LAST_EXTENT(eh);
3299 	/*
3300 	 * We should clear the EOFBLOCKS_FL flag if we are writing the
3301 	 * last block in the last extent in the file.  We test this by
3302 	 * first checking to see if the caller to
3303 	 * ext4_ext_get_blocks() was interested in the last block (or
3304 	 * a block beyond the last block) in the current extent.  If
3305 	 * this turns out to be false, we can bail out from this
3306 	 * function immediately.
3307 	 */
3308 	if (lblk + len < le32_to_cpu(last_ex->ee_block) +
3309 	    ext4_ext_get_actual_len(last_ex))
3310 		return 0;
3311 	/*
3312 	 * If the caller does appear to be planning to write at or
3313 	 * beyond the end of the current extent, we then test to see
3314 	 * if the current extent is the last extent in the file, by
3315 	 * checking to make sure it was reached via the rightmost node
3316 	 * at each level of the tree.
3317 	 */
3318 	for (i = depth-1; i >= 0; i--)
3319 		if (path[i].p_idx != EXT_LAST_INDEX(path[i].p_hdr))
3320 			return 0;
3321 	ext4_clear_inode_flag(inode, EXT4_INODE_EOFBLOCKS);
3322 	return ext4_mark_inode_dirty(handle, inode);
3323 }
3324 
3325 /**
3326  * ext4_find_delalloc_range: find delayed allocated block in the given range.
3327  *
3328  * Goes through the buffer heads in the range [lblk_start, lblk_end] and returns
3329  * whether there are any buffers marked for delayed allocation. It returns '1'
3330  * on the first delalloc'ed buffer head found. If no buffer head in the given
3331  * range is marked for delalloc, it returns 0.
3332  * lblk_start should always be <= lblk_end.
3333  * search_hint_reverse is to indicate that searching in reverse from lblk_end to
3334  * lblk_start might be more efficient (i.e., we will likely hit the delalloc'ed
3335  * block sooner). This is useful when blocks are truncated sequentially from
3336  * lblk_start towards lblk_end.
3337  */
3338 static int ext4_find_delalloc_range(struct inode *inode,
3339 				    ext4_lblk_t lblk_start,
3340 				    ext4_lblk_t lblk_end,
3341 				    int search_hint_reverse)
3342 {
3343 	struct address_space *mapping = inode->i_mapping;
3344 	struct buffer_head *head, *bh = NULL;
3345 	struct page *page;
3346 	ext4_lblk_t i, pg_lblk;
3347 	pgoff_t index;
3348 
3349 	if (!test_opt(inode->i_sb, DELALLOC))
3350 		return 0;
3351 
3352 	/* reverse search wont work if fs block size is less than page size */
3353 	if (inode->i_blkbits < PAGE_CACHE_SHIFT)
3354 		search_hint_reverse = 0;
3355 
3356 	if (search_hint_reverse)
3357 		i = lblk_end;
3358 	else
3359 		i = lblk_start;
3360 
3361 	index = i >> (PAGE_CACHE_SHIFT - inode->i_blkbits);
3362 
3363 	while ((i >= lblk_start) && (i <= lblk_end)) {
3364 		page = find_get_page(mapping, index);
3365 		if (!page)
3366 			goto nextpage;
3367 
3368 		if (!page_has_buffers(page))
3369 			goto nextpage;
3370 
3371 		head = page_buffers(page);
3372 		if (!head)
3373 			goto nextpage;
3374 
3375 		bh = head;
3376 		pg_lblk = index << (PAGE_CACHE_SHIFT -
3377 						inode->i_blkbits);
3378 		do {
3379 			if (unlikely(pg_lblk < lblk_start)) {
3380 				/*
3381 				 * This is possible when fs block size is less
3382 				 * than page size and our cluster starts/ends in
3383 				 * middle of the page. So we need to skip the
3384 				 * initial few blocks till we reach the 'lblk'
3385 				 */
3386 				pg_lblk++;
3387 				continue;
3388 			}
3389 
3390 			/* Check if the buffer is delayed allocated and that it
3391 			 * is not yet mapped. (when da-buffers are mapped during
3392 			 * their writeout, their da_mapped bit is set.)
3393 			 */
3394 			if (buffer_delay(bh) && !buffer_da_mapped(bh)) {
3395 				page_cache_release(page);
3396 				trace_ext4_find_delalloc_range(inode,
3397 						lblk_start, lblk_end,
3398 						search_hint_reverse,
3399 						1, i);
3400 				return 1;
3401 			}
3402 			if (search_hint_reverse)
3403 				i--;
3404 			else
3405 				i++;
3406 		} while ((i >= lblk_start) && (i <= lblk_end) &&
3407 				((bh = bh->b_this_page) != head));
3408 nextpage:
3409 		if (page)
3410 			page_cache_release(page);
3411 		/*
3412 		 * Move to next page. 'i' will be the first lblk in the next
3413 		 * page.
3414 		 */
3415 		if (search_hint_reverse)
3416 			index--;
3417 		else
3418 			index++;
3419 		i = index << (PAGE_CACHE_SHIFT - inode->i_blkbits);
3420 	}
3421 
3422 	trace_ext4_find_delalloc_range(inode, lblk_start, lblk_end,
3423 					search_hint_reverse, 0, 0);
3424 	return 0;
3425 }
3426 
3427 int ext4_find_delalloc_cluster(struct inode *inode, ext4_lblk_t lblk,
3428 			       int search_hint_reverse)
3429 {
3430 	struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
3431 	ext4_lblk_t lblk_start, lblk_end;
3432 	lblk_start = lblk & (~(sbi->s_cluster_ratio - 1));
3433 	lblk_end = lblk_start + sbi->s_cluster_ratio - 1;
3434 
3435 	return ext4_find_delalloc_range(inode, lblk_start, lblk_end,
3436 					search_hint_reverse);
3437 }
3438 
3439 /**
3440  * Determines how many complete clusters (out of those specified by the 'map')
3441  * are under delalloc and were reserved quota for.
3442  * This function is called when we are writing out the blocks that were
3443  * originally written with their allocation delayed, but then the space was
3444  * allocated using fallocate() before the delayed allocation could be resolved.
3445  * The cases to look for are:
3446  * ('=' indicated delayed allocated blocks
3447  *  '-' indicates non-delayed allocated blocks)
3448  * (a) partial clusters towards beginning and/or end outside of allocated range
3449  *     are not delalloc'ed.
3450  *	Ex:
3451  *	|----c---=|====c====|====c====|===-c----|
3452  *	         |++++++ allocated ++++++|
3453  *	==> 4 complete clusters in above example
3454  *
3455  * (b) partial cluster (outside of allocated range) towards either end is
3456  *     marked for delayed allocation. In this case, we will exclude that
3457  *     cluster.
3458  *	Ex:
3459  *	|----====c========|========c========|
3460  *	     |++++++ allocated ++++++|
3461  *	==> 1 complete clusters in above example
3462  *
3463  *	Ex:
3464  *	|================c================|
3465  *            |++++++ allocated ++++++|
3466  *	==> 0 complete clusters in above example
3467  *
3468  * The ext4_da_update_reserve_space will be called only if we
3469  * determine here that there were some "entire" clusters that span
3470  * this 'allocated' range.
3471  * In the non-bigalloc case, this function will just end up returning num_blks
3472  * without ever calling ext4_find_delalloc_range.
3473  */
3474 static unsigned int
3475 get_reserved_cluster_alloc(struct inode *inode, ext4_lblk_t lblk_start,
3476 			   unsigned int num_blks)
3477 {
3478 	struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
3479 	ext4_lblk_t alloc_cluster_start, alloc_cluster_end;
3480 	ext4_lblk_t lblk_from, lblk_to, c_offset;
3481 	unsigned int allocated_clusters = 0;
3482 
3483 	alloc_cluster_start = EXT4_B2C(sbi, lblk_start);
3484 	alloc_cluster_end = EXT4_B2C(sbi, lblk_start + num_blks - 1);
3485 
3486 	/* max possible clusters for this allocation */
3487 	allocated_clusters = alloc_cluster_end - alloc_cluster_start + 1;
3488 
3489 	trace_ext4_get_reserved_cluster_alloc(inode, lblk_start, num_blks);
3490 
3491 	/* Check towards left side */
3492 	c_offset = lblk_start & (sbi->s_cluster_ratio - 1);
3493 	if (c_offset) {
3494 		lblk_from = lblk_start & (~(sbi->s_cluster_ratio - 1));
3495 		lblk_to = lblk_from + c_offset - 1;
3496 
3497 		if (ext4_find_delalloc_range(inode, lblk_from, lblk_to, 0))
3498 			allocated_clusters--;
3499 	}
3500 
3501 	/* Now check towards right. */
3502 	c_offset = (lblk_start + num_blks) & (sbi->s_cluster_ratio - 1);
3503 	if (allocated_clusters && c_offset) {
3504 		lblk_from = lblk_start + num_blks;
3505 		lblk_to = lblk_from + (sbi->s_cluster_ratio - c_offset) - 1;
3506 
3507 		if (ext4_find_delalloc_range(inode, lblk_from, lblk_to, 0))
3508 			allocated_clusters--;
3509 	}
3510 
3511 	return allocated_clusters;
3512 }
3513 
3514 static int
3515 ext4_ext_handle_uninitialized_extents(handle_t *handle, struct inode *inode,
3516 			struct ext4_map_blocks *map,
3517 			struct ext4_ext_path *path, int flags,
3518 			unsigned int allocated, ext4_fsblk_t newblock)
3519 {
3520 	int ret = 0;
3521 	int err = 0;
3522 	ext4_io_end_t *io = EXT4_I(inode)->cur_aio_dio;
3523 
3524 	ext_debug("ext4_ext_handle_uninitialized_extents: inode %lu, logical "
3525 		  "block %llu, max_blocks %u, flags %x, allocated %u\n",
3526 		  inode->i_ino, (unsigned long long)map->m_lblk, map->m_len,
3527 		  flags, allocated);
3528 	ext4_ext_show_leaf(inode, path);
3529 
3530 	trace_ext4_ext_handle_uninitialized_extents(inode, map, allocated,
3531 						    newblock);
3532 
3533 	/* get_block() before submit the IO, split the extent */
3534 	if ((flags & EXT4_GET_BLOCKS_PRE_IO)) {
3535 		ret = ext4_split_unwritten_extents(handle, inode, map,
3536 						   path, flags);
3537 		/*
3538 		 * Flag the inode(non aio case) or end_io struct (aio case)
3539 		 * that this IO needs to conversion to written when IO is
3540 		 * completed
3541 		 */
3542 		if (io)
3543 			ext4_set_io_unwritten_flag(inode, io);
3544 		else
3545 			ext4_set_inode_state(inode, EXT4_STATE_DIO_UNWRITTEN);
3546 		if (ext4_should_dioread_nolock(inode))
3547 			map->m_flags |= EXT4_MAP_UNINIT;
3548 		goto out;
3549 	}
3550 	/* IO end_io complete, convert the filled extent to written */
3551 	if ((flags & EXT4_GET_BLOCKS_CONVERT)) {
3552 		ret = ext4_convert_unwritten_extents_endio(handle, inode,
3553 							path);
3554 		if (ret >= 0) {
3555 			ext4_update_inode_fsync_trans(handle, inode, 1);
3556 			err = check_eofblocks_fl(handle, inode, map->m_lblk,
3557 						 path, map->m_len);
3558 		} else
3559 			err = ret;
3560 		goto out2;
3561 	}
3562 	/* buffered IO case */
3563 	/*
3564 	 * repeat fallocate creation request
3565 	 * we already have an unwritten extent
3566 	 */
3567 	if (flags & EXT4_GET_BLOCKS_UNINIT_EXT)
3568 		goto map_out;
3569 
3570 	/* buffered READ or buffered write_begin() lookup */
3571 	if ((flags & EXT4_GET_BLOCKS_CREATE) == 0) {
3572 		/*
3573 		 * We have blocks reserved already.  We
3574 		 * return allocated blocks so that delalloc
3575 		 * won't do block reservation for us.  But
3576 		 * the buffer head will be unmapped so that
3577 		 * a read from the block returns 0s.
3578 		 */
3579 		map->m_flags |= EXT4_MAP_UNWRITTEN;
3580 		goto out1;
3581 	}
3582 
3583 	/* buffered write, writepage time, convert*/
3584 	ret = ext4_ext_convert_to_initialized(handle, inode, map, path);
3585 	if (ret >= 0)
3586 		ext4_update_inode_fsync_trans(handle, inode, 1);
3587 out:
3588 	if (ret <= 0) {
3589 		err = ret;
3590 		goto out2;
3591 	} else
3592 		allocated = ret;
3593 	map->m_flags |= EXT4_MAP_NEW;
3594 	/*
3595 	 * if we allocated more blocks than requested
3596 	 * we need to make sure we unmap the extra block
3597 	 * allocated. The actual needed block will get
3598 	 * unmapped later when we find the buffer_head marked
3599 	 * new.
3600 	 */
3601 	if (allocated > map->m_len) {
3602 		unmap_underlying_metadata_blocks(inode->i_sb->s_bdev,
3603 					newblock + map->m_len,
3604 					allocated - map->m_len);
3605 		allocated = map->m_len;
3606 	}
3607 
3608 	/*
3609 	 * If we have done fallocate with the offset that is already
3610 	 * delayed allocated, we would have block reservation
3611 	 * and quota reservation done in the delayed write path.
3612 	 * But fallocate would have already updated quota and block
3613 	 * count for this offset. So cancel these reservation
3614 	 */
3615 	if (flags & EXT4_GET_BLOCKS_DELALLOC_RESERVE) {
3616 		unsigned int reserved_clusters;
3617 		reserved_clusters = get_reserved_cluster_alloc(inode,
3618 				map->m_lblk, map->m_len);
3619 		if (reserved_clusters)
3620 			ext4_da_update_reserve_space(inode,
3621 						     reserved_clusters,
3622 						     0);
3623 	}
3624 
3625 map_out:
3626 	map->m_flags |= EXT4_MAP_MAPPED;
3627 	if ((flags & EXT4_GET_BLOCKS_KEEP_SIZE) == 0) {
3628 		err = check_eofblocks_fl(handle, inode, map->m_lblk, path,
3629 					 map->m_len);
3630 		if (err < 0)
3631 			goto out2;
3632 	}
3633 out1:
3634 	if (allocated > map->m_len)
3635 		allocated = map->m_len;
3636 	ext4_ext_show_leaf(inode, path);
3637 	map->m_pblk = newblock;
3638 	map->m_len = allocated;
3639 out2:
3640 	if (path) {
3641 		ext4_ext_drop_refs(path);
3642 		kfree(path);
3643 	}
3644 	return err ? err : allocated;
3645 }
3646 
3647 /*
3648  * get_implied_cluster_alloc - check to see if the requested
3649  * allocation (in the map structure) overlaps with a cluster already
3650  * allocated in an extent.
3651  *	@sb	The filesystem superblock structure
3652  *	@map	The requested lblk->pblk mapping
3653  *	@ex	The extent structure which might contain an implied
3654  *			cluster allocation
3655  *
3656  * This function is called by ext4_ext_map_blocks() after we failed to
3657  * find blocks that were already in the inode's extent tree.  Hence,
3658  * we know that the beginning of the requested region cannot overlap
3659  * the extent from the inode's extent tree.  There are three cases we
3660  * want to catch.  The first is this case:
3661  *
3662  *		 |--- cluster # N--|
3663  *    |--- extent ---|	|---- requested region ---|
3664  *			|==========|
3665  *
3666  * The second case that we need to test for is this one:
3667  *
3668  *   |--------- cluster # N ----------------|
3669  *	   |--- requested region --|   |------- extent ----|
3670  *	   |=======================|
3671  *
3672  * The third case is when the requested region lies between two extents
3673  * within the same cluster:
3674  *          |------------- cluster # N-------------|
3675  * |----- ex -----|                  |---- ex_right ----|
3676  *                  |------ requested region ------|
3677  *                  |================|
3678  *
3679  * In each of the above cases, we need to set the map->m_pblk and
3680  * map->m_len so it corresponds to the return the extent labelled as
3681  * "|====|" from cluster #N, since it is already in use for data in
3682  * cluster EXT4_B2C(sbi, map->m_lblk).	We will then return 1 to
3683  * signal to ext4_ext_map_blocks() that map->m_pblk should be treated
3684  * as a new "allocated" block region.  Otherwise, we will return 0 and
3685  * ext4_ext_map_blocks() will then allocate one or more new clusters
3686  * by calling ext4_mb_new_blocks().
3687  */
3688 static int get_implied_cluster_alloc(struct super_block *sb,
3689 				     struct ext4_map_blocks *map,
3690 				     struct ext4_extent *ex,
3691 				     struct ext4_ext_path *path)
3692 {
3693 	struct ext4_sb_info *sbi = EXT4_SB(sb);
3694 	ext4_lblk_t c_offset = map->m_lblk & (sbi->s_cluster_ratio-1);
3695 	ext4_lblk_t ex_cluster_start, ex_cluster_end;
3696 	ext4_lblk_t rr_cluster_start;
3697 	ext4_lblk_t ee_block = le32_to_cpu(ex->ee_block);
3698 	ext4_fsblk_t ee_start = ext4_ext_pblock(ex);
3699 	unsigned short ee_len = ext4_ext_get_actual_len(ex);
3700 
3701 	/* The extent passed in that we are trying to match */
3702 	ex_cluster_start = EXT4_B2C(sbi, ee_block);
3703 	ex_cluster_end = EXT4_B2C(sbi, ee_block + ee_len - 1);
3704 
3705 	/* The requested region passed into ext4_map_blocks() */
3706 	rr_cluster_start = EXT4_B2C(sbi, map->m_lblk);
3707 
3708 	if ((rr_cluster_start == ex_cluster_end) ||
3709 	    (rr_cluster_start == ex_cluster_start)) {
3710 		if (rr_cluster_start == ex_cluster_end)
3711 			ee_start += ee_len - 1;
3712 		map->m_pblk = (ee_start & ~(sbi->s_cluster_ratio - 1)) +
3713 			c_offset;
3714 		map->m_len = min(map->m_len,
3715 				 (unsigned) sbi->s_cluster_ratio - c_offset);
3716 		/*
3717 		 * Check for and handle this case:
3718 		 *
3719 		 *   |--------- cluster # N-------------|
3720 		 *		       |------- extent ----|
3721 		 *	   |--- requested region ---|
3722 		 *	   |===========|
3723 		 */
3724 
3725 		if (map->m_lblk < ee_block)
3726 			map->m_len = min(map->m_len, ee_block - map->m_lblk);
3727 
3728 		/*
3729 		 * Check for the case where there is already another allocated
3730 		 * block to the right of 'ex' but before the end of the cluster.
3731 		 *
3732 		 *          |------------- cluster # N-------------|
3733 		 * |----- ex -----|                  |---- ex_right ----|
3734 		 *                  |------ requested region ------|
3735 		 *                  |================|
3736 		 */
3737 		if (map->m_lblk > ee_block) {
3738 			ext4_lblk_t next = ext4_ext_next_allocated_block(path);
3739 			map->m_len = min(map->m_len, next - map->m_lblk);
3740 		}
3741 
3742 		trace_ext4_get_implied_cluster_alloc_exit(sb, map, 1);
3743 		return 1;
3744 	}
3745 
3746 	trace_ext4_get_implied_cluster_alloc_exit(sb, map, 0);
3747 	return 0;
3748 }
3749 
3750 
3751 /*
3752  * Block allocation/map/preallocation routine for extents based files
3753  *
3754  *
3755  * Need to be called with
3756  * down_read(&EXT4_I(inode)->i_data_sem) if not allocating file system block
3757  * (ie, create is zero). Otherwise down_write(&EXT4_I(inode)->i_data_sem)
3758  *
3759  * return > 0, number of of blocks already mapped/allocated
3760  *          if create == 0 and these are pre-allocated blocks
3761  *          	buffer head is unmapped
3762  *          otherwise blocks are mapped
3763  *
3764  * return = 0, if plain look up failed (blocks have not been allocated)
3765  *          buffer head is unmapped
3766  *
3767  * return < 0, error case.
3768  */
3769 int ext4_ext_map_blocks(handle_t *handle, struct inode *inode,
3770 			struct ext4_map_blocks *map, int flags)
3771 {
3772 	struct ext4_ext_path *path = NULL;
3773 	struct ext4_extent newex, *ex, *ex2;
3774 	struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
3775 	ext4_fsblk_t newblock = 0;
3776 	int free_on_err = 0, err = 0, depth, ret;
3777 	unsigned int allocated = 0, offset = 0;
3778 	unsigned int allocated_clusters = 0;
3779 	struct ext4_allocation_request ar;
3780 	ext4_io_end_t *io = EXT4_I(inode)->cur_aio_dio;
3781 	ext4_lblk_t cluster_offset;
3782 
3783 	ext_debug("blocks %u/%u requested for inode %lu\n",
3784 		  map->m_lblk, map->m_len, inode->i_ino);
3785 	trace_ext4_ext_map_blocks_enter(inode, map->m_lblk, map->m_len, flags);
3786 
3787 	/* check in cache */
3788 	if (ext4_ext_in_cache(inode, map->m_lblk, &newex)) {
3789 		if (!newex.ee_start_lo && !newex.ee_start_hi) {
3790 			if ((sbi->s_cluster_ratio > 1) &&
3791 			    ext4_find_delalloc_cluster(inode, map->m_lblk, 0))
3792 				map->m_flags |= EXT4_MAP_FROM_CLUSTER;
3793 
3794 			if ((flags & EXT4_GET_BLOCKS_CREATE) == 0) {
3795 				/*
3796 				 * block isn't allocated yet and
3797 				 * user doesn't want to allocate it
3798 				 */
3799 				goto out2;
3800 			}
3801 			/* we should allocate requested block */
3802 		} else {
3803 			/* block is already allocated */
3804 			if (sbi->s_cluster_ratio > 1)
3805 				map->m_flags |= EXT4_MAP_FROM_CLUSTER;
3806 			newblock = map->m_lblk
3807 				   - le32_to_cpu(newex.ee_block)
3808 				   + ext4_ext_pblock(&newex);
3809 			/* number of remaining blocks in the extent */
3810 			allocated = ext4_ext_get_actual_len(&newex) -
3811 				(map->m_lblk - le32_to_cpu(newex.ee_block));
3812 			goto out;
3813 		}
3814 	}
3815 
3816 	/* find extent for this block */
3817 	path = ext4_ext_find_extent(inode, map->m_lblk, NULL);
3818 	if (IS_ERR(path)) {
3819 		err = PTR_ERR(path);
3820 		path = NULL;
3821 		goto out2;
3822 	}
3823 
3824 	depth = ext_depth(inode);
3825 
3826 	/*
3827 	 * consistent leaf must not be empty;
3828 	 * this situation is possible, though, _during_ tree modification;
3829 	 * this is why assert can't be put in ext4_ext_find_extent()
3830 	 */
3831 	if (unlikely(path[depth].p_ext == NULL && depth != 0)) {
3832 		EXT4_ERROR_INODE(inode, "bad extent address "
3833 				 "lblock: %lu, depth: %d pblock %lld",
3834 				 (unsigned long) map->m_lblk, depth,
3835 				 path[depth].p_block);
3836 		err = -EIO;
3837 		goto out2;
3838 	}
3839 
3840 	ex = path[depth].p_ext;
3841 	if (ex) {
3842 		ext4_lblk_t ee_block = le32_to_cpu(ex->ee_block);
3843 		ext4_fsblk_t ee_start = ext4_ext_pblock(ex);
3844 		unsigned short ee_len;
3845 
3846 		/*
3847 		 * Uninitialized extents are treated as holes, except that
3848 		 * we split out initialized portions during a write.
3849 		 */
3850 		ee_len = ext4_ext_get_actual_len(ex);
3851 
3852 		trace_ext4_ext_show_extent(inode, ee_block, ee_start, ee_len);
3853 
3854 		/* if found extent covers block, simply return it */
3855 		if (in_range(map->m_lblk, ee_block, ee_len)) {
3856 			newblock = map->m_lblk - ee_block + ee_start;
3857 			/* number of remaining blocks in the extent */
3858 			allocated = ee_len - (map->m_lblk - ee_block);
3859 			ext_debug("%u fit into %u:%d -> %llu\n", map->m_lblk,
3860 				  ee_block, ee_len, newblock);
3861 
3862 			/*
3863 			 * Do not put uninitialized extent
3864 			 * in the cache
3865 			 */
3866 			if (!ext4_ext_is_uninitialized(ex)) {
3867 				ext4_ext_put_in_cache(inode, ee_block,
3868 					ee_len, ee_start);
3869 				goto out;
3870 			}
3871 			ret = ext4_ext_handle_uninitialized_extents(
3872 				handle, inode, map, path, flags,
3873 				allocated, newblock);
3874 			return ret;
3875 		}
3876 	}
3877 
3878 	if ((sbi->s_cluster_ratio > 1) &&
3879 	    ext4_find_delalloc_cluster(inode, map->m_lblk, 0))
3880 		map->m_flags |= EXT4_MAP_FROM_CLUSTER;
3881 
3882 	/*
3883 	 * requested block isn't allocated yet;
3884 	 * we couldn't try to create block if create flag is zero
3885 	 */
3886 	if ((flags & EXT4_GET_BLOCKS_CREATE) == 0) {
3887 		/*
3888 		 * put just found gap into cache to speed up
3889 		 * subsequent requests
3890 		 */
3891 		ext4_ext_put_gap_in_cache(inode, path, map->m_lblk);
3892 		goto out2;
3893 	}
3894 
3895 	/*
3896 	 * Okay, we need to do block allocation.
3897 	 */
3898 	map->m_flags &= ~EXT4_MAP_FROM_CLUSTER;
3899 	newex.ee_block = cpu_to_le32(map->m_lblk);
3900 	cluster_offset = map->m_lblk & (sbi->s_cluster_ratio-1);
3901 
3902 	/*
3903 	 * If we are doing bigalloc, check to see if the extent returned
3904 	 * by ext4_ext_find_extent() implies a cluster we can use.
3905 	 */
3906 	if (cluster_offset && ex &&
3907 	    get_implied_cluster_alloc(inode->i_sb, map, ex, path)) {
3908 		ar.len = allocated = map->m_len;
3909 		newblock = map->m_pblk;
3910 		map->m_flags |= EXT4_MAP_FROM_CLUSTER;
3911 		goto got_allocated_blocks;
3912 	}
3913 
3914 	/* find neighbour allocated blocks */
3915 	ar.lleft = map->m_lblk;
3916 	err = ext4_ext_search_left(inode, path, &ar.lleft, &ar.pleft);
3917 	if (err)
3918 		goto out2;
3919 	ar.lright = map->m_lblk;
3920 	ex2 = NULL;
3921 	err = ext4_ext_search_right(inode, path, &ar.lright, &ar.pright, &ex2);
3922 	if (err)
3923 		goto out2;
3924 
3925 	/* Check if the extent after searching to the right implies a
3926 	 * cluster we can use. */
3927 	if ((sbi->s_cluster_ratio > 1) && ex2 &&
3928 	    get_implied_cluster_alloc(inode->i_sb, map, ex2, path)) {
3929 		ar.len = allocated = map->m_len;
3930 		newblock = map->m_pblk;
3931 		map->m_flags |= EXT4_MAP_FROM_CLUSTER;
3932 		goto got_allocated_blocks;
3933 	}
3934 
3935 	/*
3936 	 * See if request is beyond maximum number of blocks we can have in
3937 	 * a single extent. For an initialized extent this limit is
3938 	 * EXT_INIT_MAX_LEN and for an uninitialized extent this limit is
3939 	 * EXT_UNINIT_MAX_LEN.
3940 	 */
3941 	if (map->m_len > EXT_INIT_MAX_LEN &&
3942 	    !(flags & EXT4_GET_BLOCKS_UNINIT_EXT))
3943 		map->m_len = EXT_INIT_MAX_LEN;
3944 	else if (map->m_len > EXT_UNINIT_MAX_LEN &&
3945 		 (flags & EXT4_GET_BLOCKS_UNINIT_EXT))
3946 		map->m_len = EXT_UNINIT_MAX_LEN;
3947 
3948 	/* Check if we can really insert (m_lblk)::(m_lblk + m_len) extent */
3949 	newex.ee_len = cpu_to_le16(map->m_len);
3950 	err = ext4_ext_check_overlap(sbi, inode, &newex, path);
3951 	if (err)
3952 		allocated = ext4_ext_get_actual_len(&newex);
3953 	else
3954 		allocated = map->m_len;
3955 
3956 	/* allocate new block */
3957 	ar.inode = inode;
3958 	ar.goal = ext4_ext_find_goal(inode, path, map->m_lblk);
3959 	ar.logical = map->m_lblk;
3960 	/*
3961 	 * We calculate the offset from the beginning of the cluster
3962 	 * for the logical block number, since when we allocate a
3963 	 * physical cluster, the physical block should start at the
3964 	 * same offset from the beginning of the cluster.  This is
3965 	 * needed so that future calls to get_implied_cluster_alloc()
3966 	 * work correctly.
3967 	 */
3968 	offset = map->m_lblk & (sbi->s_cluster_ratio - 1);
3969 	ar.len = EXT4_NUM_B2C(sbi, offset+allocated);
3970 	ar.goal -= offset;
3971 	ar.logical -= offset;
3972 	if (S_ISREG(inode->i_mode))
3973 		ar.flags = EXT4_MB_HINT_DATA;
3974 	else
3975 		/* disable in-core preallocation for non-regular files */
3976 		ar.flags = 0;
3977 	if (flags & EXT4_GET_BLOCKS_NO_NORMALIZE)
3978 		ar.flags |= EXT4_MB_HINT_NOPREALLOC;
3979 	newblock = ext4_mb_new_blocks(handle, &ar, &err);
3980 	if (!newblock)
3981 		goto out2;
3982 	ext_debug("allocate new block: goal %llu, found %llu/%u\n",
3983 		  ar.goal, newblock, allocated);
3984 	free_on_err = 1;
3985 	allocated_clusters = ar.len;
3986 	ar.len = EXT4_C2B(sbi, ar.len) - offset;
3987 	if (ar.len > allocated)
3988 		ar.len = allocated;
3989 
3990 got_allocated_blocks:
3991 	/* try to insert new extent into found leaf and return */
3992 	ext4_ext_store_pblock(&newex, newblock + offset);
3993 	newex.ee_len = cpu_to_le16(ar.len);
3994 	/* Mark uninitialized */
3995 	if (flags & EXT4_GET_BLOCKS_UNINIT_EXT){
3996 		ext4_ext_mark_uninitialized(&newex);
3997 		/*
3998 		 * io_end structure was created for every IO write to an
3999 		 * uninitialized extent. To avoid unnecessary conversion,
4000 		 * here we flag the IO that really needs the conversion.
4001 		 * For non asycn direct IO case, flag the inode state
4002 		 * that we need to perform conversion when IO is done.
4003 		 */
4004 		if ((flags & EXT4_GET_BLOCKS_PRE_IO)) {
4005 			if (io)
4006 				ext4_set_io_unwritten_flag(inode, io);
4007 			else
4008 				ext4_set_inode_state(inode,
4009 						     EXT4_STATE_DIO_UNWRITTEN);
4010 		}
4011 		if (ext4_should_dioread_nolock(inode))
4012 			map->m_flags |= EXT4_MAP_UNINIT;
4013 	}
4014 
4015 	err = 0;
4016 	if ((flags & EXT4_GET_BLOCKS_KEEP_SIZE) == 0)
4017 		err = check_eofblocks_fl(handle, inode, map->m_lblk,
4018 					 path, ar.len);
4019 	if (!err)
4020 		err = ext4_ext_insert_extent(handle, inode, path,
4021 					     &newex, flags);
4022 	if (err && free_on_err) {
4023 		int fb_flags = flags & EXT4_GET_BLOCKS_DELALLOC_RESERVE ?
4024 			EXT4_FREE_BLOCKS_NO_QUOT_UPDATE : 0;
4025 		/* free data blocks we just allocated */
4026 		/* not a good idea to call discard here directly,
4027 		 * but otherwise we'd need to call it every free() */
4028 		ext4_discard_preallocations(inode);
4029 		ext4_free_blocks(handle, inode, NULL, ext4_ext_pblock(&newex),
4030 				 ext4_ext_get_actual_len(&newex), fb_flags);
4031 		goto out2;
4032 	}
4033 
4034 	/* previous routine could use block we allocated */
4035 	newblock = ext4_ext_pblock(&newex);
4036 	allocated = ext4_ext_get_actual_len(&newex);
4037 	if (allocated > map->m_len)
4038 		allocated = map->m_len;
4039 	map->m_flags |= EXT4_MAP_NEW;
4040 
4041 	/*
4042 	 * Update reserved blocks/metadata blocks after successful
4043 	 * block allocation which had been deferred till now.
4044 	 */
4045 	if (flags & EXT4_GET_BLOCKS_DELALLOC_RESERVE) {
4046 		unsigned int reserved_clusters;
4047 		/*
4048 		 * Check how many clusters we had reserved this allocated range
4049 		 */
4050 		reserved_clusters = get_reserved_cluster_alloc(inode,
4051 						map->m_lblk, allocated);
4052 		if (map->m_flags & EXT4_MAP_FROM_CLUSTER) {
4053 			if (reserved_clusters) {
4054 				/*
4055 				 * We have clusters reserved for this range.
4056 				 * But since we are not doing actual allocation
4057 				 * and are simply using blocks from previously
4058 				 * allocated cluster, we should release the
4059 				 * reservation and not claim quota.
4060 				 */
4061 				ext4_da_update_reserve_space(inode,
4062 						reserved_clusters, 0);
4063 			}
4064 		} else {
4065 			BUG_ON(allocated_clusters < reserved_clusters);
4066 			/* We will claim quota for all newly allocated blocks.*/
4067 			ext4_da_update_reserve_space(inode, allocated_clusters,
4068 							1);
4069 			if (reserved_clusters < allocated_clusters) {
4070 				struct ext4_inode_info *ei = EXT4_I(inode);
4071 				int reservation = allocated_clusters -
4072 						  reserved_clusters;
4073 				/*
4074 				 * It seems we claimed few clusters outside of
4075 				 * the range of this allocation. We should give
4076 				 * it back to the reservation pool. This can
4077 				 * happen in the following case:
4078 				 *
4079 				 * * Suppose s_cluster_ratio is 4 (i.e., each
4080 				 *   cluster has 4 blocks. Thus, the clusters
4081 				 *   are [0-3],[4-7],[8-11]...
4082 				 * * First comes delayed allocation write for
4083 				 *   logical blocks 10 & 11. Since there were no
4084 				 *   previous delayed allocated blocks in the
4085 				 *   range [8-11], we would reserve 1 cluster
4086 				 *   for this write.
4087 				 * * Next comes write for logical blocks 3 to 8.
4088 				 *   In this case, we will reserve 2 clusters
4089 				 *   (for [0-3] and [4-7]; and not for [8-11] as
4090 				 *   that range has a delayed allocated blocks.
4091 				 *   Thus total reserved clusters now becomes 3.
4092 				 * * Now, during the delayed allocation writeout
4093 				 *   time, we will first write blocks [3-8] and
4094 				 *   allocate 3 clusters for writing these
4095 				 *   blocks. Also, we would claim all these
4096 				 *   three clusters above.
4097 				 * * Now when we come here to writeout the
4098 				 *   blocks [10-11], we would expect to claim
4099 				 *   the reservation of 1 cluster we had made
4100 				 *   (and we would claim it since there are no
4101 				 *   more delayed allocated blocks in the range
4102 				 *   [8-11]. But our reserved cluster count had
4103 				 *   already gone to 0.
4104 				 *
4105 				 *   Thus, at the step 4 above when we determine
4106 				 *   that there are still some unwritten delayed
4107 				 *   allocated blocks outside of our current
4108 				 *   block range, we should increment the
4109 				 *   reserved clusters count so that when the
4110 				 *   remaining blocks finally gets written, we
4111 				 *   could claim them.
4112 				 */
4113 				dquot_reserve_block(inode,
4114 						EXT4_C2B(sbi, reservation));
4115 				spin_lock(&ei->i_block_reservation_lock);
4116 				ei->i_reserved_data_blocks += reservation;
4117 				spin_unlock(&ei->i_block_reservation_lock);
4118 			}
4119 		}
4120 	}
4121 
4122 	/*
4123 	 * Cache the extent and update transaction to commit on fdatasync only
4124 	 * when it is _not_ an uninitialized extent.
4125 	 */
4126 	if ((flags & EXT4_GET_BLOCKS_UNINIT_EXT) == 0) {
4127 		ext4_ext_put_in_cache(inode, map->m_lblk, allocated, newblock);
4128 		ext4_update_inode_fsync_trans(handle, inode, 1);
4129 	} else
4130 		ext4_update_inode_fsync_trans(handle, inode, 0);
4131 out:
4132 	if (allocated > map->m_len)
4133 		allocated = map->m_len;
4134 	ext4_ext_show_leaf(inode, path);
4135 	map->m_flags |= EXT4_MAP_MAPPED;
4136 	map->m_pblk = newblock;
4137 	map->m_len = allocated;
4138 out2:
4139 	if (path) {
4140 		ext4_ext_drop_refs(path);
4141 		kfree(path);
4142 	}
4143 
4144 	trace_ext4_ext_map_blocks_exit(inode, map->m_lblk,
4145 		newblock, map->m_len, err ? err : allocated);
4146 
4147 	return err ? err : allocated;
4148 }
4149 
4150 void ext4_ext_truncate(struct inode *inode)
4151 {
4152 	struct address_space *mapping = inode->i_mapping;
4153 	struct super_block *sb = inode->i_sb;
4154 	ext4_lblk_t last_block;
4155 	handle_t *handle;
4156 	loff_t page_len;
4157 	int err = 0;
4158 
4159 	/*
4160 	 * finish any pending end_io work so we won't run the risk of
4161 	 * converting any truncated blocks to initialized later
4162 	 */
4163 	ext4_flush_completed_IO(inode);
4164 
4165 	/*
4166 	 * probably first extent we're gonna free will be last in block
4167 	 */
4168 	err = ext4_writepage_trans_blocks(inode);
4169 	handle = ext4_journal_start(inode, err);
4170 	if (IS_ERR(handle))
4171 		return;
4172 
4173 	if (inode->i_size % PAGE_CACHE_SIZE != 0) {
4174 		page_len = PAGE_CACHE_SIZE -
4175 			(inode->i_size & (PAGE_CACHE_SIZE - 1));
4176 
4177 		err = ext4_discard_partial_page_buffers(handle,
4178 			mapping, inode->i_size, page_len, 0);
4179 
4180 		if (err)
4181 			goto out_stop;
4182 	}
4183 
4184 	if (ext4_orphan_add(handle, inode))
4185 		goto out_stop;
4186 
4187 	down_write(&EXT4_I(inode)->i_data_sem);
4188 	ext4_ext_invalidate_cache(inode);
4189 
4190 	ext4_discard_preallocations(inode);
4191 
4192 	/*
4193 	 * TODO: optimization is possible here.
4194 	 * Probably we need not scan at all,
4195 	 * because page truncation is enough.
4196 	 */
4197 
4198 	/* we have to know where to truncate from in crash case */
4199 	EXT4_I(inode)->i_disksize = inode->i_size;
4200 	ext4_mark_inode_dirty(handle, inode);
4201 
4202 	last_block = (inode->i_size + sb->s_blocksize - 1)
4203 			>> EXT4_BLOCK_SIZE_BITS(sb);
4204 	err = ext4_ext_remove_space(inode, last_block, EXT_MAX_BLOCKS - 1);
4205 
4206 	/* In a multi-transaction truncate, we only make the final
4207 	 * transaction synchronous.
4208 	 */
4209 	if (IS_SYNC(inode))
4210 		ext4_handle_sync(handle);
4211 
4212 	up_write(&EXT4_I(inode)->i_data_sem);
4213 
4214 out_stop:
4215 	/*
4216 	 * If this was a simple ftruncate() and the file will remain alive,
4217 	 * then we need to clear up the orphan record which we created above.
4218 	 * However, if this was a real unlink then we were called by
4219 	 * ext4_delete_inode(), and we allow that function to clean up the
4220 	 * orphan info for us.
4221 	 */
4222 	if (inode->i_nlink)
4223 		ext4_orphan_del(handle, inode);
4224 
4225 	inode->i_mtime = inode->i_ctime = ext4_current_time(inode);
4226 	ext4_mark_inode_dirty(handle, inode);
4227 	ext4_journal_stop(handle);
4228 }
4229 
4230 static void ext4_falloc_update_inode(struct inode *inode,
4231 				int mode, loff_t new_size, int update_ctime)
4232 {
4233 	struct timespec now;
4234 
4235 	if (update_ctime) {
4236 		now = current_fs_time(inode->i_sb);
4237 		if (!timespec_equal(&inode->i_ctime, &now))
4238 			inode->i_ctime = now;
4239 	}
4240 	/*
4241 	 * Update only when preallocation was requested beyond
4242 	 * the file size.
4243 	 */
4244 	if (!(mode & FALLOC_FL_KEEP_SIZE)) {
4245 		if (new_size > i_size_read(inode))
4246 			i_size_write(inode, new_size);
4247 		if (new_size > EXT4_I(inode)->i_disksize)
4248 			ext4_update_i_disksize(inode, new_size);
4249 	} else {
4250 		/*
4251 		 * Mark that we allocate beyond EOF so the subsequent truncate
4252 		 * can proceed even if the new size is the same as i_size.
4253 		 */
4254 		if (new_size > i_size_read(inode))
4255 			ext4_set_inode_flag(inode, EXT4_INODE_EOFBLOCKS);
4256 	}
4257 
4258 }
4259 
4260 /*
4261  * preallocate space for a file. This implements ext4's fallocate file
4262  * operation, which gets called from sys_fallocate system call.
4263  * For block-mapped files, posix_fallocate should fall back to the method
4264  * of writing zeroes to the required new blocks (the same behavior which is
4265  * expected for file systems which do not support fallocate() system call).
4266  */
4267 long ext4_fallocate(struct file *file, int mode, loff_t offset, loff_t len)
4268 {
4269 	struct inode *inode = file->f_path.dentry->d_inode;
4270 	handle_t *handle;
4271 	loff_t new_size;
4272 	unsigned int max_blocks;
4273 	int ret = 0;
4274 	int ret2 = 0;
4275 	int retries = 0;
4276 	int flags;
4277 	struct ext4_map_blocks map;
4278 	unsigned int credits, blkbits = inode->i_blkbits;
4279 
4280 	/*
4281 	 * currently supporting (pre)allocate mode for extent-based
4282 	 * files _only_
4283 	 */
4284 	if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)))
4285 		return -EOPNOTSUPP;
4286 
4287 	/* Return error if mode is not supported */
4288 	if (mode & ~(FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE))
4289 		return -EOPNOTSUPP;
4290 
4291 	if (mode & FALLOC_FL_PUNCH_HOLE)
4292 		return ext4_punch_hole(file, offset, len);
4293 
4294 	trace_ext4_fallocate_enter(inode, offset, len, mode);
4295 	map.m_lblk = offset >> blkbits;
4296 	/*
4297 	 * We can't just convert len to max_blocks because
4298 	 * If blocksize = 4096 offset = 3072 and len = 2048
4299 	 */
4300 	max_blocks = (EXT4_BLOCK_ALIGN(len + offset, blkbits) >> blkbits)
4301 		- map.m_lblk;
4302 	/*
4303 	 * credits to insert 1 extent into extent tree
4304 	 */
4305 	credits = ext4_chunk_trans_blocks(inode, max_blocks);
4306 	mutex_lock(&inode->i_mutex);
4307 	ret = inode_newsize_ok(inode, (len + offset));
4308 	if (ret) {
4309 		mutex_unlock(&inode->i_mutex);
4310 		trace_ext4_fallocate_exit(inode, offset, max_blocks, ret);
4311 		return ret;
4312 	}
4313 	flags = EXT4_GET_BLOCKS_CREATE_UNINIT_EXT;
4314 	if (mode & FALLOC_FL_KEEP_SIZE)
4315 		flags |= EXT4_GET_BLOCKS_KEEP_SIZE;
4316 	/*
4317 	 * Don't normalize the request if it can fit in one extent so
4318 	 * that it doesn't get unnecessarily split into multiple
4319 	 * extents.
4320 	 */
4321 	if (len <= EXT_UNINIT_MAX_LEN << blkbits)
4322 		flags |= EXT4_GET_BLOCKS_NO_NORMALIZE;
4323 retry:
4324 	while (ret >= 0 && ret < max_blocks) {
4325 		map.m_lblk = map.m_lblk + ret;
4326 		map.m_len = max_blocks = max_blocks - ret;
4327 		handle = ext4_journal_start(inode, credits);
4328 		if (IS_ERR(handle)) {
4329 			ret = PTR_ERR(handle);
4330 			break;
4331 		}
4332 		ret = ext4_map_blocks(handle, inode, &map, flags);
4333 		if (ret <= 0) {
4334 #ifdef EXT4FS_DEBUG
4335 			WARN_ON(ret <= 0);
4336 			printk(KERN_ERR "%s: ext4_ext_map_blocks "
4337 				    "returned error inode#%lu, block=%u, "
4338 				    "max_blocks=%u", __func__,
4339 				    inode->i_ino, map.m_lblk, max_blocks);
4340 #endif
4341 			ext4_mark_inode_dirty(handle, inode);
4342 			ret2 = ext4_journal_stop(handle);
4343 			break;
4344 		}
4345 		if ((map.m_lblk + ret) >= (EXT4_BLOCK_ALIGN(offset + len,
4346 						blkbits) >> blkbits))
4347 			new_size = offset + len;
4348 		else
4349 			new_size = ((loff_t) map.m_lblk + ret) << blkbits;
4350 
4351 		ext4_falloc_update_inode(inode, mode, new_size,
4352 					 (map.m_flags & EXT4_MAP_NEW));
4353 		ext4_mark_inode_dirty(handle, inode);
4354 		ret2 = ext4_journal_stop(handle);
4355 		if (ret2)
4356 			break;
4357 	}
4358 	if (ret == -ENOSPC &&
4359 			ext4_should_retry_alloc(inode->i_sb, &retries)) {
4360 		ret = 0;
4361 		goto retry;
4362 	}
4363 	mutex_unlock(&inode->i_mutex);
4364 	trace_ext4_fallocate_exit(inode, offset, max_blocks,
4365 				ret > 0 ? ret2 : ret);
4366 	return ret > 0 ? ret2 : ret;
4367 }
4368 
4369 /*
4370  * This function convert a range of blocks to written extents
4371  * The caller of this function will pass the start offset and the size.
4372  * all unwritten extents within this range will be converted to
4373  * written extents.
4374  *
4375  * This function is called from the direct IO end io call back
4376  * function, to convert the fallocated extents after IO is completed.
4377  * Returns 0 on success.
4378  */
4379 int ext4_convert_unwritten_extents(struct inode *inode, loff_t offset,
4380 				    ssize_t len)
4381 {
4382 	handle_t *handle;
4383 	unsigned int max_blocks;
4384 	int ret = 0;
4385 	int ret2 = 0;
4386 	struct ext4_map_blocks map;
4387 	unsigned int credits, blkbits = inode->i_blkbits;
4388 
4389 	map.m_lblk = offset >> blkbits;
4390 	/*
4391 	 * We can't just convert len to max_blocks because
4392 	 * If blocksize = 4096 offset = 3072 and len = 2048
4393 	 */
4394 	max_blocks = ((EXT4_BLOCK_ALIGN(len + offset, blkbits) >> blkbits) -
4395 		      map.m_lblk);
4396 	/*
4397 	 * credits to insert 1 extent into extent tree
4398 	 */
4399 	credits = ext4_chunk_trans_blocks(inode, max_blocks);
4400 	while (ret >= 0 && ret < max_blocks) {
4401 		map.m_lblk += ret;
4402 		map.m_len = (max_blocks -= ret);
4403 		handle = ext4_journal_start(inode, credits);
4404 		if (IS_ERR(handle)) {
4405 			ret = PTR_ERR(handle);
4406 			break;
4407 		}
4408 		ret = ext4_map_blocks(handle, inode, &map,
4409 				      EXT4_GET_BLOCKS_IO_CONVERT_EXT);
4410 		if (ret <= 0) {
4411 			WARN_ON(ret <= 0);
4412 			printk(KERN_ERR "%s: ext4_ext_map_blocks "
4413 				    "returned error inode#%lu, block=%u, "
4414 				    "max_blocks=%u", __func__,
4415 				    inode->i_ino, map.m_lblk, map.m_len);
4416 		}
4417 		ext4_mark_inode_dirty(handle, inode);
4418 		ret2 = ext4_journal_stop(handle);
4419 		if (ret <= 0 || ret2 )
4420 			break;
4421 	}
4422 	return ret > 0 ? ret2 : ret;
4423 }
4424 
4425 /*
4426  * Callback function called for each extent to gather FIEMAP information.
4427  */
4428 static int ext4_ext_fiemap_cb(struct inode *inode, ext4_lblk_t next,
4429 		       struct ext4_ext_cache *newex, struct ext4_extent *ex,
4430 		       void *data)
4431 {
4432 	__u64	logical;
4433 	__u64	physical;
4434 	__u64	length;
4435 	__u32	flags = 0;
4436 	int		ret = 0;
4437 	struct fiemap_extent_info *fieinfo = data;
4438 	unsigned char blksize_bits;
4439 
4440 	blksize_bits = inode->i_sb->s_blocksize_bits;
4441 	logical = (__u64)newex->ec_block << blksize_bits;
4442 
4443 	if (newex->ec_start == 0) {
4444 		/*
4445 		 * No extent in extent-tree contains block @newex->ec_start,
4446 		 * then the block may stay in 1)a hole or 2)delayed-extent.
4447 		 *
4448 		 * Holes or delayed-extents are processed as follows.
4449 		 * 1. lookup dirty pages with specified range in pagecache.
4450 		 *    If no page is got, then there is no delayed-extent and
4451 		 *    return with EXT_CONTINUE.
4452 		 * 2. find the 1st mapped buffer,
4453 		 * 3. check if the mapped buffer is both in the request range
4454 		 *    and a delayed buffer. If not, there is no delayed-extent,
4455 		 *    then return.
4456 		 * 4. a delayed-extent is found, the extent will be collected.
4457 		 */
4458 		ext4_lblk_t	end = 0;
4459 		pgoff_t		last_offset;
4460 		pgoff_t		offset;
4461 		pgoff_t		index;
4462 		pgoff_t		start_index = 0;
4463 		struct page	**pages = NULL;
4464 		struct buffer_head *bh = NULL;
4465 		struct buffer_head *head = NULL;
4466 		unsigned int nr_pages = PAGE_SIZE / sizeof(struct page *);
4467 
4468 		pages = kmalloc(PAGE_SIZE, GFP_KERNEL);
4469 		if (pages == NULL)
4470 			return -ENOMEM;
4471 
4472 		offset = logical >> PAGE_SHIFT;
4473 repeat:
4474 		last_offset = offset;
4475 		head = NULL;
4476 		ret = find_get_pages_tag(inode->i_mapping, &offset,
4477 					PAGECACHE_TAG_DIRTY, nr_pages, pages);
4478 
4479 		if (!(flags & FIEMAP_EXTENT_DELALLOC)) {
4480 			/* First time, try to find a mapped buffer. */
4481 			if (ret == 0) {
4482 out:
4483 				for (index = 0; index < ret; index++)
4484 					page_cache_release(pages[index]);
4485 				/* just a hole. */
4486 				kfree(pages);
4487 				return EXT_CONTINUE;
4488 			}
4489 			index = 0;
4490 
4491 next_page:
4492 			/* Try to find the 1st mapped buffer. */
4493 			end = ((__u64)pages[index]->index << PAGE_SHIFT) >>
4494 				  blksize_bits;
4495 			if (!page_has_buffers(pages[index]))
4496 				goto out;
4497 			head = page_buffers(pages[index]);
4498 			if (!head)
4499 				goto out;
4500 
4501 			index++;
4502 			bh = head;
4503 			do {
4504 				if (end >= newex->ec_block +
4505 					newex->ec_len)
4506 					/* The buffer is out of
4507 					 * the request range.
4508 					 */
4509 					goto out;
4510 
4511 				if (buffer_mapped(bh) &&
4512 				    end >= newex->ec_block) {
4513 					start_index = index - 1;
4514 					/* get the 1st mapped buffer. */
4515 					goto found_mapped_buffer;
4516 				}
4517 
4518 				bh = bh->b_this_page;
4519 				end++;
4520 			} while (bh != head);
4521 
4522 			/* No mapped buffer in the range found in this page,
4523 			 * We need to look up next page.
4524 			 */
4525 			if (index >= ret) {
4526 				/* There is no page left, but we need to limit
4527 				 * newex->ec_len.
4528 				 */
4529 				newex->ec_len = end - newex->ec_block;
4530 				goto out;
4531 			}
4532 			goto next_page;
4533 		} else {
4534 			/*Find contiguous delayed buffers. */
4535 			if (ret > 0 && pages[0]->index == last_offset)
4536 				head = page_buffers(pages[0]);
4537 			bh = head;
4538 			index = 1;
4539 			start_index = 0;
4540 		}
4541 
4542 found_mapped_buffer:
4543 		if (bh != NULL && buffer_delay(bh)) {
4544 			/* 1st or contiguous delayed buffer found. */
4545 			if (!(flags & FIEMAP_EXTENT_DELALLOC)) {
4546 				/*
4547 				 * 1st delayed buffer found, record
4548 				 * the start of extent.
4549 				 */
4550 				flags |= FIEMAP_EXTENT_DELALLOC;
4551 				newex->ec_block = end;
4552 				logical = (__u64)end << blksize_bits;
4553 			}
4554 			/* Find contiguous delayed buffers. */
4555 			do {
4556 				if (!buffer_delay(bh))
4557 					goto found_delayed_extent;
4558 				bh = bh->b_this_page;
4559 				end++;
4560 			} while (bh != head);
4561 
4562 			for (; index < ret; index++) {
4563 				if (!page_has_buffers(pages[index])) {
4564 					bh = NULL;
4565 					break;
4566 				}
4567 				head = page_buffers(pages[index]);
4568 				if (!head) {
4569 					bh = NULL;
4570 					break;
4571 				}
4572 
4573 				if (pages[index]->index !=
4574 				    pages[start_index]->index + index
4575 				    - start_index) {
4576 					/* Blocks are not contiguous. */
4577 					bh = NULL;
4578 					break;
4579 				}
4580 				bh = head;
4581 				do {
4582 					if (!buffer_delay(bh))
4583 						/* Delayed-extent ends. */
4584 						goto found_delayed_extent;
4585 					bh = bh->b_this_page;
4586 					end++;
4587 				} while (bh != head);
4588 			}
4589 		} else if (!(flags & FIEMAP_EXTENT_DELALLOC))
4590 			/* a hole found. */
4591 			goto out;
4592 
4593 found_delayed_extent:
4594 		newex->ec_len = min(end - newex->ec_block,
4595 						(ext4_lblk_t)EXT_INIT_MAX_LEN);
4596 		if (ret == nr_pages && bh != NULL &&
4597 			newex->ec_len < EXT_INIT_MAX_LEN &&
4598 			buffer_delay(bh)) {
4599 			/* Have not collected an extent and continue. */
4600 			for (index = 0; index < ret; index++)
4601 				page_cache_release(pages[index]);
4602 			goto repeat;
4603 		}
4604 
4605 		for (index = 0; index < ret; index++)
4606 			page_cache_release(pages[index]);
4607 		kfree(pages);
4608 	}
4609 
4610 	physical = (__u64)newex->ec_start << blksize_bits;
4611 	length =   (__u64)newex->ec_len << blksize_bits;
4612 
4613 	if (ex && ext4_ext_is_uninitialized(ex))
4614 		flags |= FIEMAP_EXTENT_UNWRITTEN;
4615 
4616 	if (next == EXT_MAX_BLOCKS)
4617 		flags |= FIEMAP_EXTENT_LAST;
4618 
4619 	ret = fiemap_fill_next_extent(fieinfo, logical, physical,
4620 					length, flags);
4621 	if (ret < 0)
4622 		return ret;
4623 	if (ret == 1)
4624 		return EXT_BREAK;
4625 	return EXT_CONTINUE;
4626 }
4627 /* fiemap flags we can handle specified here */
4628 #define EXT4_FIEMAP_FLAGS	(FIEMAP_FLAG_SYNC|FIEMAP_FLAG_XATTR)
4629 
4630 static int ext4_xattr_fiemap(struct inode *inode,
4631 				struct fiemap_extent_info *fieinfo)
4632 {
4633 	__u64 physical = 0;
4634 	__u64 length;
4635 	__u32 flags = FIEMAP_EXTENT_LAST;
4636 	int blockbits = inode->i_sb->s_blocksize_bits;
4637 	int error = 0;
4638 
4639 	/* in-inode? */
4640 	if (ext4_test_inode_state(inode, EXT4_STATE_XATTR)) {
4641 		struct ext4_iloc iloc;
4642 		int offset;	/* offset of xattr in inode */
4643 
4644 		error = ext4_get_inode_loc(inode, &iloc);
4645 		if (error)
4646 			return error;
4647 		physical = iloc.bh->b_blocknr << blockbits;
4648 		offset = EXT4_GOOD_OLD_INODE_SIZE +
4649 				EXT4_I(inode)->i_extra_isize;
4650 		physical += offset;
4651 		length = EXT4_SB(inode->i_sb)->s_inode_size - offset;
4652 		flags |= FIEMAP_EXTENT_DATA_INLINE;
4653 		brelse(iloc.bh);
4654 	} else { /* external block */
4655 		physical = EXT4_I(inode)->i_file_acl << blockbits;
4656 		length = inode->i_sb->s_blocksize;
4657 	}
4658 
4659 	if (physical)
4660 		error = fiemap_fill_next_extent(fieinfo, 0, physical,
4661 						length, flags);
4662 	return (error < 0 ? error : 0);
4663 }
4664 
4665 /*
4666  * ext4_ext_punch_hole
4667  *
4668  * Punches a hole of "length" bytes in a file starting
4669  * at byte "offset"
4670  *
4671  * @inode:  The inode of the file to punch a hole in
4672  * @offset: The starting byte offset of the hole
4673  * @length: The length of the hole
4674  *
4675  * Returns the number of blocks removed or negative on err
4676  */
4677 int ext4_ext_punch_hole(struct file *file, loff_t offset, loff_t length)
4678 {
4679 	struct inode *inode = file->f_path.dentry->d_inode;
4680 	struct super_block *sb = inode->i_sb;
4681 	ext4_lblk_t first_block, stop_block;
4682 	struct address_space *mapping = inode->i_mapping;
4683 	handle_t *handle;
4684 	loff_t first_page, last_page, page_len;
4685 	loff_t first_page_offset, last_page_offset;
4686 	int credits, err = 0;
4687 
4688 	/* No need to punch hole beyond i_size */
4689 	if (offset >= inode->i_size)
4690 		return 0;
4691 
4692 	/*
4693 	 * If the hole extends beyond i_size, set the hole
4694 	 * to end after the page that contains i_size
4695 	 */
4696 	if (offset + length > inode->i_size) {
4697 		length = inode->i_size +
4698 		   PAGE_CACHE_SIZE - (inode->i_size & (PAGE_CACHE_SIZE - 1)) -
4699 		   offset;
4700 	}
4701 
4702 	first_page = (offset + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
4703 	last_page = (offset + length) >> PAGE_CACHE_SHIFT;
4704 
4705 	first_page_offset = first_page << PAGE_CACHE_SHIFT;
4706 	last_page_offset = last_page << PAGE_CACHE_SHIFT;
4707 
4708 	/*
4709 	 * Write out all dirty pages to avoid race conditions
4710 	 * Then release them.
4711 	 */
4712 	if (mapping->nrpages && mapping_tagged(mapping, PAGECACHE_TAG_DIRTY)) {
4713 		err = filemap_write_and_wait_range(mapping,
4714 			offset, offset + length - 1);
4715 
4716 		if (err)
4717 			return err;
4718 	}
4719 
4720 	/* Now release the pages */
4721 	if (last_page_offset > first_page_offset) {
4722 		truncate_inode_pages_range(mapping, first_page_offset,
4723 					   last_page_offset-1);
4724 	}
4725 
4726 	/* finish any pending end_io work */
4727 	ext4_flush_completed_IO(inode);
4728 
4729 	credits = ext4_writepage_trans_blocks(inode);
4730 	handle = ext4_journal_start(inode, credits);
4731 	if (IS_ERR(handle))
4732 		return PTR_ERR(handle);
4733 
4734 	err = ext4_orphan_add(handle, inode);
4735 	if (err)
4736 		goto out;
4737 
4738 	/*
4739 	 * Now we need to zero out the non-page-aligned data in the
4740 	 * pages at the start and tail of the hole, and unmap the buffer
4741 	 * heads for the block aligned regions of the page that were
4742 	 * completely zeroed.
4743 	 */
4744 	if (first_page > last_page) {
4745 		/*
4746 		 * If the file space being truncated is contained within a page
4747 		 * just zero out and unmap the middle of that page
4748 		 */
4749 		err = ext4_discard_partial_page_buffers(handle,
4750 			mapping, offset, length, 0);
4751 
4752 		if (err)
4753 			goto out;
4754 	} else {
4755 		/*
4756 		 * zero out and unmap the partial page that contains
4757 		 * the start of the hole
4758 		 */
4759 		page_len  = first_page_offset - offset;
4760 		if (page_len > 0) {
4761 			err = ext4_discard_partial_page_buffers(handle, mapping,
4762 						   offset, page_len, 0);
4763 			if (err)
4764 				goto out;
4765 		}
4766 
4767 		/*
4768 		 * zero out and unmap the partial page that contains
4769 		 * the end of the hole
4770 		 */
4771 		page_len = offset + length - last_page_offset;
4772 		if (page_len > 0) {
4773 			err = ext4_discard_partial_page_buffers(handle, mapping,
4774 					last_page_offset, page_len, 0);
4775 			if (err)
4776 				goto out;
4777 		}
4778 	}
4779 
4780 	/*
4781 	 * If i_size is contained in the last page, we need to
4782 	 * unmap and zero the partial page after i_size
4783 	 */
4784 	if (inode->i_size >> PAGE_CACHE_SHIFT == last_page &&
4785 	   inode->i_size % PAGE_CACHE_SIZE != 0) {
4786 
4787 		page_len = PAGE_CACHE_SIZE -
4788 			(inode->i_size & (PAGE_CACHE_SIZE - 1));
4789 
4790 		if (page_len > 0) {
4791 			err = ext4_discard_partial_page_buffers(handle,
4792 			  mapping, inode->i_size, page_len, 0);
4793 
4794 			if (err)
4795 				goto out;
4796 		}
4797 	}
4798 
4799 	first_block = (offset + sb->s_blocksize - 1) >>
4800 		EXT4_BLOCK_SIZE_BITS(sb);
4801 	stop_block = (offset + length) >> EXT4_BLOCK_SIZE_BITS(sb);
4802 
4803 	/* If there are no blocks to remove, return now */
4804 	if (first_block >= stop_block)
4805 		goto out;
4806 
4807 	down_write(&EXT4_I(inode)->i_data_sem);
4808 	ext4_ext_invalidate_cache(inode);
4809 	ext4_discard_preallocations(inode);
4810 
4811 	err = ext4_ext_remove_space(inode, first_block, stop_block - 1);
4812 
4813 	ext4_ext_invalidate_cache(inode);
4814 	ext4_discard_preallocations(inode);
4815 
4816 	if (IS_SYNC(inode))
4817 		ext4_handle_sync(handle);
4818 
4819 	up_write(&EXT4_I(inode)->i_data_sem);
4820 
4821 out:
4822 	ext4_orphan_del(handle, inode);
4823 	inode->i_mtime = inode->i_ctime = ext4_current_time(inode);
4824 	ext4_mark_inode_dirty(handle, inode);
4825 	ext4_journal_stop(handle);
4826 	return err;
4827 }
4828 int ext4_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
4829 		__u64 start, __u64 len)
4830 {
4831 	ext4_lblk_t start_blk;
4832 	int error = 0;
4833 
4834 	/* fallback to generic here if not in extents fmt */
4835 	if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)))
4836 		return generic_block_fiemap(inode, fieinfo, start, len,
4837 			ext4_get_block);
4838 
4839 	if (fiemap_check_flags(fieinfo, EXT4_FIEMAP_FLAGS))
4840 		return -EBADR;
4841 
4842 	if (fieinfo->fi_flags & FIEMAP_FLAG_XATTR) {
4843 		error = ext4_xattr_fiemap(inode, fieinfo);
4844 	} else {
4845 		ext4_lblk_t len_blks;
4846 		__u64 last_blk;
4847 
4848 		start_blk = start >> inode->i_sb->s_blocksize_bits;
4849 		last_blk = (start + len - 1) >> inode->i_sb->s_blocksize_bits;
4850 		if (last_blk >= EXT_MAX_BLOCKS)
4851 			last_blk = EXT_MAX_BLOCKS-1;
4852 		len_blks = ((ext4_lblk_t) last_blk) - start_blk + 1;
4853 
4854 		/*
4855 		 * Walk the extent tree gathering extent information.
4856 		 * ext4_ext_fiemap_cb will push extents back to user.
4857 		 */
4858 		error = ext4_ext_walk_space(inode, start_blk, len_blks,
4859 					  ext4_ext_fiemap_cb, fieinfo);
4860 	}
4861 
4862 	return error;
4863 }
4864