xref: /openbmc/linux/fs/nilfs2/btree.c (revision e2ad626f)
1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3  * NILFS B-tree.
4  *
5  * Copyright (C) 2005-2008 Nippon Telegraph and Telephone Corporation.
6  *
7  * Written by Koji Sato.
8  */
9 
10 #include <linux/slab.h>
11 #include <linux/string.h>
12 #include <linux/errno.h>
13 #include <linux/pagevec.h>
14 #include "nilfs.h"
15 #include "page.h"
16 #include "btnode.h"
17 #include "btree.h"
18 #include "alloc.h"
19 #include "dat.h"
20 
21 static void __nilfs_btree_init(struct nilfs_bmap *bmap);
22 
23 static struct nilfs_btree_path *nilfs_btree_alloc_path(void)
24 {
25 	struct nilfs_btree_path *path;
26 	int level = NILFS_BTREE_LEVEL_DATA;
27 
28 	path = kmem_cache_alloc(nilfs_btree_path_cache, GFP_NOFS);
29 	if (path == NULL)
30 		goto out;
31 
32 	for (; level < NILFS_BTREE_LEVEL_MAX; level++) {
33 		path[level].bp_bh = NULL;
34 		path[level].bp_sib_bh = NULL;
35 		path[level].bp_index = 0;
36 		path[level].bp_oldreq.bpr_ptr = NILFS_BMAP_INVALID_PTR;
37 		path[level].bp_newreq.bpr_ptr = NILFS_BMAP_INVALID_PTR;
38 		path[level].bp_op = NULL;
39 	}
40 
41 out:
42 	return path;
43 }
44 
45 static void nilfs_btree_free_path(struct nilfs_btree_path *path)
46 {
47 	int level = NILFS_BTREE_LEVEL_DATA;
48 
49 	for (; level < NILFS_BTREE_LEVEL_MAX; level++)
50 		brelse(path[level].bp_bh);
51 
52 	kmem_cache_free(nilfs_btree_path_cache, path);
53 }
54 
55 /*
56  * B-tree node operations
57  */
58 static int nilfs_btree_get_new_block(const struct nilfs_bmap *btree,
59 				     __u64 ptr, struct buffer_head **bhp)
60 {
61 	struct inode *btnc_inode = NILFS_BMAP_I(btree)->i_assoc_inode;
62 	struct address_space *btnc = btnc_inode->i_mapping;
63 	struct buffer_head *bh;
64 
65 	bh = nilfs_btnode_create_block(btnc, ptr);
66 	if (!bh)
67 		return -ENOMEM;
68 
69 	set_buffer_nilfs_volatile(bh);
70 	*bhp = bh;
71 	return 0;
72 }
73 
74 static int nilfs_btree_node_get_flags(const struct nilfs_btree_node *node)
75 {
76 	return node->bn_flags;
77 }
78 
79 static void
80 nilfs_btree_node_set_flags(struct nilfs_btree_node *node, int flags)
81 {
82 	node->bn_flags = flags;
83 }
84 
85 static int nilfs_btree_node_root(const struct nilfs_btree_node *node)
86 {
87 	return nilfs_btree_node_get_flags(node) & NILFS_BTREE_NODE_ROOT;
88 }
89 
90 static int nilfs_btree_node_get_level(const struct nilfs_btree_node *node)
91 {
92 	return node->bn_level;
93 }
94 
95 static void
96 nilfs_btree_node_set_level(struct nilfs_btree_node *node, int level)
97 {
98 	node->bn_level = level;
99 }
100 
101 static int nilfs_btree_node_get_nchildren(const struct nilfs_btree_node *node)
102 {
103 	return le16_to_cpu(node->bn_nchildren);
104 }
105 
106 static void
107 nilfs_btree_node_set_nchildren(struct nilfs_btree_node *node, int nchildren)
108 {
109 	node->bn_nchildren = cpu_to_le16(nchildren);
110 }
111 
112 static int nilfs_btree_node_size(const struct nilfs_bmap *btree)
113 {
114 	return i_blocksize(btree->b_inode);
115 }
116 
117 static int nilfs_btree_nchildren_per_block(const struct nilfs_bmap *btree)
118 {
119 	return btree->b_nchildren_per_block;
120 }
121 
122 static __le64 *
123 nilfs_btree_node_dkeys(const struct nilfs_btree_node *node)
124 {
125 	return (__le64 *)((char *)(node + 1) +
126 			  (nilfs_btree_node_root(node) ?
127 			   0 : NILFS_BTREE_NODE_EXTRA_PAD_SIZE));
128 }
129 
130 static __le64 *
131 nilfs_btree_node_dptrs(const struct nilfs_btree_node *node, int ncmax)
132 {
133 	return (__le64 *)(nilfs_btree_node_dkeys(node) + ncmax);
134 }
135 
136 static __u64
137 nilfs_btree_node_get_key(const struct nilfs_btree_node *node, int index)
138 {
139 	return le64_to_cpu(*(nilfs_btree_node_dkeys(node) + index));
140 }
141 
142 static void
143 nilfs_btree_node_set_key(struct nilfs_btree_node *node, int index, __u64 key)
144 {
145 	*(nilfs_btree_node_dkeys(node) + index) = cpu_to_le64(key);
146 }
147 
148 static __u64
149 nilfs_btree_node_get_ptr(const struct nilfs_btree_node *node, int index,
150 			 int ncmax)
151 {
152 	return le64_to_cpu(*(nilfs_btree_node_dptrs(node, ncmax) + index));
153 }
154 
155 static void
156 nilfs_btree_node_set_ptr(struct nilfs_btree_node *node, int index, __u64 ptr,
157 			 int ncmax)
158 {
159 	*(nilfs_btree_node_dptrs(node, ncmax) + index) = cpu_to_le64(ptr);
160 }
161 
162 static void nilfs_btree_node_init(struct nilfs_btree_node *node, int flags,
163 				  int level, int nchildren, int ncmax,
164 				  const __u64 *keys, const __u64 *ptrs)
165 {
166 	__le64 *dkeys;
167 	__le64 *dptrs;
168 	int i;
169 
170 	nilfs_btree_node_set_flags(node, flags);
171 	nilfs_btree_node_set_level(node, level);
172 	nilfs_btree_node_set_nchildren(node, nchildren);
173 
174 	dkeys = nilfs_btree_node_dkeys(node);
175 	dptrs = nilfs_btree_node_dptrs(node, ncmax);
176 	for (i = 0; i < nchildren; i++) {
177 		dkeys[i] = cpu_to_le64(keys[i]);
178 		dptrs[i] = cpu_to_le64(ptrs[i]);
179 	}
180 }
181 
182 /* Assume the buffer heads corresponding to left and right are locked. */
183 static void nilfs_btree_node_move_left(struct nilfs_btree_node *left,
184 				       struct nilfs_btree_node *right,
185 				       int n, int lncmax, int rncmax)
186 {
187 	__le64 *ldkeys, *rdkeys;
188 	__le64 *ldptrs, *rdptrs;
189 	int lnchildren, rnchildren;
190 
191 	ldkeys = nilfs_btree_node_dkeys(left);
192 	ldptrs = nilfs_btree_node_dptrs(left, lncmax);
193 	lnchildren = nilfs_btree_node_get_nchildren(left);
194 
195 	rdkeys = nilfs_btree_node_dkeys(right);
196 	rdptrs = nilfs_btree_node_dptrs(right, rncmax);
197 	rnchildren = nilfs_btree_node_get_nchildren(right);
198 
199 	memcpy(ldkeys + lnchildren, rdkeys, n * sizeof(*rdkeys));
200 	memcpy(ldptrs + lnchildren, rdptrs, n * sizeof(*rdptrs));
201 	memmove(rdkeys, rdkeys + n, (rnchildren - n) * sizeof(*rdkeys));
202 	memmove(rdptrs, rdptrs + n, (rnchildren - n) * sizeof(*rdptrs));
203 
204 	lnchildren += n;
205 	rnchildren -= n;
206 	nilfs_btree_node_set_nchildren(left, lnchildren);
207 	nilfs_btree_node_set_nchildren(right, rnchildren);
208 }
209 
210 /* Assume that the buffer heads corresponding to left and right are locked. */
211 static void nilfs_btree_node_move_right(struct nilfs_btree_node *left,
212 					struct nilfs_btree_node *right,
213 					int n, int lncmax, int rncmax)
214 {
215 	__le64 *ldkeys, *rdkeys;
216 	__le64 *ldptrs, *rdptrs;
217 	int lnchildren, rnchildren;
218 
219 	ldkeys = nilfs_btree_node_dkeys(left);
220 	ldptrs = nilfs_btree_node_dptrs(left, lncmax);
221 	lnchildren = nilfs_btree_node_get_nchildren(left);
222 
223 	rdkeys = nilfs_btree_node_dkeys(right);
224 	rdptrs = nilfs_btree_node_dptrs(right, rncmax);
225 	rnchildren = nilfs_btree_node_get_nchildren(right);
226 
227 	memmove(rdkeys + n, rdkeys, rnchildren * sizeof(*rdkeys));
228 	memmove(rdptrs + n, rdptrs, rnchildren * sizeof(*rdptrs));
229 	memcpy(rdkeys, ldkeys + lnchildren - n, n * sizeof(*rdkeys));
230 	memcpy(rdptrs, ldptrs + lnchildren - n, n * sizeof(*rdptrs));
231 
232 	lnchildren -= n;
233 	rnchildren += n;
234 	nilfs_btree_node_set_nchildren(left, lnchildren);
235 	nilfs_btree_node_set_nchildren(right, rnchildren);
236 }
237 
238 /* Assume that the buffer head corresponding to node is locked. */
239 static void nilfs_btree_node_insert(struct nilfs_btree_node *node, int index,
240 				    __u64 key, __u64 ptr, int ncmax)
241 {
242 	__le64 *dkeys;
243 	__le64 *dptrs;
244 	int nchildren;
245 
246 	dkeys = nilfs_btree_node_dkeys(node);
247 	dptrs = nilfs_btree_node_dptrs(node, ncmax);
248 	nchildren = nilfs_btree_node_get_nchildren(node);
249 	if (index < nchildren) {
250 		memmove(dkeys + index + 1, dkeys + index,
251 			(nchildren - index) * sizeof(*dkeys));
252 		memmove(dptrs + index + 1, dptrs + index,
253 			(nchildren - index) * sizeof(*dptrs));
254 	}
255 	dkeys[index] = cpu_to_le64(key);
256 	dptrs[index] = cpu_to_le64(ptr);
257 	nchildren++;
258 	nilfs_btree_node_set_nchildren(node, nchildren);
259 }
260 
261 /* Assume that the buffer head corresponding to node is locked. */
262 static void nilfs_btree_node_delete(struct nilfs_btree_node *node, int index,
263 				    __u64 *keyp, __u64 *ptrp, int ncmax)
264 {
265 	__u64 key;
266 	__u64 ptr;
267 	__le64 *dkeys;
268 	__le64 *dptrs;
269 	int nchildren;
270 
271 	dkeys = nilfs_btree_node_dkeys(node);
272 	dptrs = nilfs_btree_node_dptrs(node, ncmax);
273 	key = le64_to_cpu(dkeys[index]);
274 	ptr = le64_to_cpu(dptrs[index]);
275 	nchildren = nilfs_btree_node_get_nchildren(node);
276 	if (keyp != NULL)
277 		*keyp = key;
278 	if (ptrp != NULL)
279 		*ptrp = ptr;
280 
281 	if (index < nchildren - 1) {
282 		memmove(dkeys + index, dkeys + index + 1,
283 			(nchildren - index - 1) * sizeof(*dkeys));
284 		memmove(dptrs + index, dptrs + index + 1,
285 			(nchildren - index - 1) * sizeof(*dptrs));
286 	}
287 	nchildren--;
288 	nilfs_btree_node_set_nchildren(node, nchildren);
289 }
290 
291 static int nilfs_btree_node_lookup(const struct nilfs_btree_node *node,
292 				   __u64 key, int *indexp)
293 {
294 	__u64 nkey;
295 	int index, low, high, s;
296 
297 	/* binary search */
298 	low = 0;
299 	high = nilfs_btree_node_get_nchildren(node) - 1;
300 	index = 0;
301 	s = 0;
302 	while (low <= high) {
303 		index = (low + high) / 2;
304 		nkey = nilfs_btree_node_get_key(node, index);
305 		if (nkey == key) {
306 			s = 0;
307 			goto out;
308 		} else if (nkey < key) {
309 			low = index + 1;
310 			s = -1;
311 		} else {
312 			high = index - 1;
313 			s = 1;
314 		}
315 	}
316 
317 	/* adjust index */
318 	if (nilfs_btree_node_get_level(node) > NILFS_BTREE_LEVEL_NODE_MIN) {
319 		if (s > 0 && index > 0)
320 			index--;
321 	} else if (s < 0)
322 		index++;
323 
324  out:
325 	*indexp = index;
326 
327 	return s == 0;
328 }
329 
330 /**
331  * nilfs_btree_node_broken - verify consistency of btree node
332  * @node: btree node block to be examined
333  * @size: node size (in bytes)
334  * @inode: host inode of btree
335  * @blocknr: block number
336  *
337  * Return Value: If node is broken, 1 is returned. Otherwise, 0 is returned.
338  */
339 static int nilfs_btree_node_broken(const struct nilfs_btree_node *node,
340 				   size_t size, struct inode *inode,
341 				   sector_t blocknr)
342 {
343 	int level, flags, nchildren;
344 	int ret = 0;
345 
346 	level = nilfs_btree_node_get_level(node);
347 	flags = nilfs_btree_node_get_flags(node);
348 	nchildren = nilfs_btree_node_get_nchildren(node);
349 
350 	if (unlikely(level < NILFS_BTREE_LEVEL_NODE_MIN ||
351 		     level >= NILFS_BTREE_LEVEL_MAX ||
352 		     (flags & NILFS_BTREE_NODE_ROOT) ||
353 		     nchildren < 0 ||
354 		     nchildren > NILFS_BTREE_NODE_NCHILDREN_MAX(size))) {
355 		nilfs_crit(inode->i_sb,
356 			   "bad btree node (ino=%lu, blocknr=%llu): level = %d, flags = 0x%x, nchildren = %d",
357 			   inode->i_ino, (unsigned long long)blocknr, level,
358 			   flags, nchildren);
359 		ret = 1;
360 	}
361 	return ret;
362 }
363 
364 /**
365  * nilfs_btree_root_broken - verify consistency of btree root node
366  * @node: btree root node to be examined
367  * @inode: host inode of btree
368  *
369  * Return Value: If node is broken, 1 is returned. Otherwise, 0 is returned.
370  */
371 static int nilfs_btree_root_broken(const struct nilfs_btree_node *node,
372 				   struct inode *inode)
373 {
374 	int level, flags, nchildren;
375 	int ret = 0;
376 
377 	level = nilfs_btree_node_get_level(node);
378 	flags = nilfs_btree_node_get_flags(node);
379 	nchildren = nilfs_btree_node_get_nchildren(node);
380 
381 	if (unlikely(level < NILFS_BTREE_LEVEL_NODE_MIN ||
382 		     level >= NILFS_BTREE_LEVEL_MAX ||
383 		     nchildren < 0 ||
384 		     nchildren > NILFS_BTREE_ROOT_NCHILDREN_MAX)) {
385 		nilfs_crit(inode->i_sb,
386 			   "bad btree root (ino=%lu): level = %d, flags = 0x%x, nchildren = %d",
387 			   inode->i_ino, level, flags, nchildren);
388 		ret = 1;
389 	}
390 	return ret;
391 }
392 
393 int nilfs_btree_broken_node_block(struct buffer_head *bh)
394 {
395 	struct inode *inode;
396 	int ret;
397 
398 	if (buffer_nilfs_checked(bh))
399 		return 0;
400 
401 	inode = bh->b_folio->mapping->host;
402 	ret = nilfs_btree_node_broken((struct nilfs_btree_node *)bh->b_data,
403 				      bh->b_size, inode, bh->b_blocknr);
404 	if (likely(!ret))
405 		set_buffer_nilfs_checked(bh);
406 	return ret;
407 }
408 
409 static struct nilfs_btree_node *
410 nilfs_btree_get_root(const struct nilfs_bmap *btree)
411 {
412 	return (struct nilfs_btree_node *)btree->b_u.u_data;
413 }
414 
415 static struct nilfs_btree_node *
416 nilfs_btree_get_nonroot_node(const struct nilfs_btree_path *path, int level)
417 {
418 	return (struct nilfs_btree_node *)path[level].bp_bh->b_data;
419 }
420 
421 static struct nilfs_btree_node *
422 nilfs_btree_get_sib_node(const struct nilfs_btree_path *path, int level)
423 {
424 	return (struct nilfs_btree_node *)path[level].bp_sib_bh->b_data;
425 }
426 
427 static int nilfs_btree_height(const struct nilfs_bmap *btree)
428 {
429 	return nilfs_btree_node_get_level(nilfs_btree_get_root(btree)) + 1;
430 }
431 
432 static struct nilfs_btree_node *
433 nilfs_btree_get_node(const struct nilfs_bmap *btree,
434 		     const struct nilfs_btree_path *path,
435 		     int level, int *ncmaxp)
436 {
437 	struct nilfs_btree_node *node;
438 
439 	if (level == nilfs_btree_height(btree) - 1) {
440 		node = nilfs_btree_get_root(btree);
441 		*ncmaxp = NILFS_BTREE_ROOT_NCHILDREN_MAX;
442 	} else {
443 		node = nilfs_btree_get_nonroot_node(path, level);
444 		*ncmaxp = nilfs_btree_nchildren_per_block(btree);
445 	}
446 	return node;
447 }
448 
449 static int nilfs_btree_bad_node(const struct nilfs_bmap *btree,
450 				struct nilfs_btree_node *node, int level)
451 {
452 	if (unlikely(nilfs_btree_node_get_level(node) != level)) {
453 		dump_stack();
454 		nilfs_crit(btree->b_inode->i_sb,
455 			   "btree level mismatch (ino=%lu): %d != %d",
456 			   btree->b_inode->i_ino,
457 			   nilfs_btree_node_get_level(node), level);
458 		return 1;
459 	}
460 	return 0;
461 }
462 
463 struct nilfs_btree_readahead_info {
464 	struct nilfs_btree_node *node;	/* parent node */
465 	int max_ra_blocks;		/* max nof blocks to read ahead */
466 	int index;			/* current index on the parent node */
467 	int ncmax;			/* nof children in the parent node */
468 };
469 
470 static int __nilfs_btree_get_block(const struct nilfs_bmap *btree, __u64 ptr,
471 				   struct buffer_head **bhp,
472 				   const struct nilfs_btree_readahead_info *ra)
473 {
474 	struct inode *btnc_inode = NILFS_BMAP_I(btree)->i_assoc_inode;
475 	struct address_space *btnc = btnc_inode->i_mapping;
476 	struct buffer_head *bh, *ra_bh;
477 	sector_t submit_ptr = 0;
478 	int ret;
479 
480 	ret = nilfs_btnode_submit_block(btnc, ptr, 0, REQ_OP_READ, &bh,
481 					&submit_ptr);
482 	if (ret) {
483 		if (likely(ret == -EEXIST))
484 			goto out_check;
485 		if (ret == -ENOENT) {
486 			/*
487 			 * Block address translation failed due to invalid
488 			 * value of 'ptr'.  In this case, return internal code
489 			 * -EINVAL (broken bmap) to notify bmap layer of fatal
490 			 * metadata corruption.
491 			 */
492 			ret = -EINVAL;
493 		}
494 		return ret;
495 	}
496 
497 	if (ra) {
498 		int i, n;
499 		__u64 ptr2;
500 
501 		/* read ahead sibling nodes */
502 		for (n = ra->max_ra_blocks, i = ra->index + 1;
503 		     n > 0 && i < ra->ncmax; n--, i++) {
504 			ptr2 = nilfs_btree_node_get_ptr(ra->node, i, ra->ncmax);
505 
506 			ret = nilfs_btnode_submit_block(btnc, ptr2, 0,
507 						REQ_OP_READ | REQ_RAHEAD,
508 						&ra_bh, &submit_ptr);
509 			if (likely(!ret || ret == -EEXIST))
510 				brelse(ra_bh);
511 			else if (ret != -EBUSY)
512 				break;
513 			if (!buffer_locked(bh))
514 				goto out_no_wait;
515 		}
516 	}
517 
518 	wait_on_buffer(bh);
519 
520  out_no_wait:
521 	if (!buffer_uptodate(bh)) {
522 		nilfs_err(btree->b_inode->i_sb,
523 			  "I/O error reading b-tree node block (ino=%lu, blocknr=%llu)",
524 			  btree->b_inode->i_ino, (unsigned long long)ptr);
525 		brelse(bh);
526 		return -EIO;
527 	}
528 
529  out_check:
530 	if (nilfs_btree_broken_node_block(bh)) {
531 		clear_buffer_uptodate(bh);
532 		brelse(bh);
533 		return -EINVAL;
534 	}
535 
536 	*bhp = bh;
537 	return 0;
538 }
539 
540 static int nilfs_btree_get_block(const struct nilfs_bmap *btree, __u64 ptr,
541 				   struct buffer_head **bhp)
542 {
543 	return __nilfs_btree_get_block(btree, ptr, bhp, NULL);
544 }
545 
546 static int nilfs_btree_do_lookup(const struct nilfs_bmap *btree,
547 				 struct nilfs_btree_path *path,
548 				 __u64 key, __u64 *ptrp, int minlevel,
549 				 int readahead)
550 {
551 	struct nilfs_btree_node *node;
552 	struct nilfs_btree_readahead_info p, *ra;
553 	__u64 ptr;
554 	int level, index, found, ncmax, ret;
555 
556 	node = nilfs_btree_get_root(btree);
557 	level = nilfs_btree_node_get_level(node);
558 	if (level < minlevel || nilfs_btree_node_get_nchildren(node) <= 0)
559 		return -ENOENT;
560 
561 	found = nilfs_btree_node_lookup(node, key, &index);
562 	ptr = nilfs_btree_node_get_ptr(node, index,
563 				       NILFS_BTREE_ROOT_NCHILDREN_MAX);
564 	path[level].bp_bh = NULL;
565 	path[level].bp_index = index;
566 
567 	ncmax = nilfs_btree_nchildren_per_block(btree);
568 
569 	while (--level >= minlevel) {
570 		ra = NULL;
571 		if (level == NILFS_BTREE_LEVEL_NODE_MIN && readahead) {
572 			p.node = nilfs_btree_get_node(btree, path, level + 1,
573 						      &p.ncmax);
574 			p.index = index;
575 			p.max_ra_blocks = 7;
576 			ra = &p;
577 		}
578 		ret = __nilfs_btree_get_block(btree, ptr, &path[level].bp_bh,
579 					      ra);
580 		if (ret < 0)
581 			return ret;
582 
583 		node = nilfs_btree_get_nonroot_node(path, level);
584 		if (nilfs_btree_bad_node(btree, node, level))
585 			return -EINVAL;
586 		if (!found)
587 			found = nilfs_btree_node_lookup(node, key, &index);
588 		else
589 			index = 0;
590 		if (index < ncmax) {
591 			ptr = nilfs_btree_node_get_ptr(node, index, ncmax);
592 		} else {
593 			WARN_ON(found || level != NILFS_BTREE_LEVEL_NODE_MIN);
594 			/* insert */
595 			ptr = NILFS_BMAP_INVALID_PTR;
596 		}
597 		path[level].bp_index = index;
598 	}
599 	if (!found)
600 		return -ENOENT;
601 
602 	if (ptrp != NULL)
603 		*ptrp = ptr;
604 
605 	return 0;
606 }
607 
608 static int nilfs_btree_do_lookup_last(const struct nilfs_bmap *btree,
609 				      struct nilfs_btree_path *path,
610 				      __u64 *keyp, __u64 *ptrp)
611 {
612 	struct nilfs_btree_node *node;
613 	__u64 ptr;
614 	int index, level, ncmax, ret;
615 
616 	node = nilfs_btree_get_root(btree);
617 	index = nilfs_btree_node_get_nchildren(node) - 1;
618 	if (index < 0)
619 		return -ENOENT;
620 	level = nilfs_btree_node_get_level(node);
621 	ptr = nilfs_btree_node_get_ptr(node, index,
622 				       NILFS_BTREE_ROOT_NCHILDREN_MAX);
623 	path[level].bp_bh = NULL;
624 	path[level].bp_index = index;
625 	ncmax = nilfs_btree_nchildren_per_block(btree);
626 
627 	for (level--; level > 0; level--) {
628 		ret = nilfs_btree_get_block(btree, ptr, &path[level].bp_bh);
629 		if (ret < 0)
630 			return ret;
631 		node = nilfs_btree_get_nonroot_node(path, level);
632 		if (nilfs_btree_bad_node(btree, node, level))
633 			return -EINVAL;
634 		index = nilfs_btree_node_get_nchildren(node) - 1;
635 		ptr = nilfs_btree_node_get_ptr(node, index, ncmax);
636 		path[level].bp_index = index;
637 	}
638 
639 	if (keyp != NULL)
640 		*keyp = nilfs_btree_node_get_key(node, index);
641 	if (ptrp != NULL)
642 		*ptrp = ptr;
643 
644 	return 0;
645 }
646 
647 /**
648  * nilfs_btree_get_next_key - get next valid key from btree path array
649  * @btree: bmap struct of btree
650  * @path: array of nilfs_btree_path struct
651  * @minlevel: start level
652  * @nextkey: place to store the next valid key
653  *
654  * Return Value: If a next key was found, 0 is returned. Otherwise,
655  * -ENOENT is returned.
656  */
657 static int nilfs_btree_get_next_key(const struct nilfs_bmap *btree,
658 				    const struct nilfs_btree_path *path,
659 				    int minlevel, __u64 *nextkey)
660 {
661 	struct nilfs_btree_node *node;
662 	int maxlevel = nilfs_btree_height(btree) - 1;
663 	int index, next_adj, level;
664 
665 	/* Next index is already set to bp_index for leaf nodes. */
666 	next_adj = 0;
667 	for (level = minlevel; level <= maxlevel; level++) {
668 		if (level == maxlevel)
669 			node = nilfs_btree_get_root(btree);
670 		else
671 			node = nilfs_btree_get_nonroot_node(path, level);
672 
673 		index = path[level].bp_index + next_adj;
674 		if (index < nilfs_btree_node_get_nchildren(node)) {
675 			/* Next key is in this node */
676 			*nextkey = nilfs_btree_node_get_key(node, index);
677 			return 0;
678 		}
679 		/* For non-leaf nodes, next index is stored at bp_index + 1. */
680 		next_adj = 1;
681 	}
682 	return -ENOENT;
683 }
684 
685 static int nilfs_btree_lookup(const struct nilfs_bmap *btree,
686 			      __u64 key, int level, __u64 *ptrp)
687 {
688 	struct nilfs_btree_path *path;
689 	int ret;
690 
691 	path = nilfs_btree_alloc_path();
692 	if (path == NULL)
693 		return -ENOMEM;
694 
695 	ret = nilfs_btree_do_lookup(btree, path, key, ptrp, level, 0);
696 
697 	nilfs_btree_free_path(path);
698 
699 	return ret;
700 }
701 
702 static int nilfs_btree_lookup_contig(const struct nilfs_bmap *btree,
703 				     __u64 key, __u64 *ptrp,
704 				     unsigned int maxblocks)
705 {
706 	struct nilfs_btree_path *path;
707 	struct nilfs_btree_node *node;
708 	struct inode *dat = NULL;
709 	__u64 ptr, ptr2;
710 	sector_t blocknr;
711 	int level = NILFS_BTREE_LEVEL_NODE_MIN;
712 	int ret, cnt, index, maxlevel, ncmax;
713 	struct nilfs_btree_readahead_info p;
714 
715 	path = nilfs_btree_alloc_path();
716 	if (path == NULL)
717 		return -ENOMEM;
718 
719 	ret = nilfs_btree_do_lookup(btree, path, key, &ptr, level, 1);
720 	if (ret < 0)
721 		goto out;
722 
723 	if (NILFS_BMAP_USE_VBN(btree)) {
724 		dat = nilfs_bmap_get_dat(btree);
725 		ret = nilfs_dat_translate(dat, ptr, &blocknr);
726 		if (ret < 0)
727 			goto out;
728 		ptr = blocknr;
729 	}
730 	cnt = 1;
731 	if (cnt == maxblocks)
732 		goto end;
733 
734 	maxlevel = nilfs_btree_height(btree) - 1;
735 	node = nilfs_btree_get_node(btree, path, level, &ncmax);
736 	index = path[level].bp_index + 1;
737 	for (;;) {
738 		while (index < nilfs_btree_node_get_nchildren(node)) {
739 			if (nilfs_btree_node_get_key(node, index) !=
740 			    key + cnt)
741 				goto end;
742 			ptr2 = nilfs_btree_node_get_ptr(node, index, ncmax);
743 			if (dat) {
744 				ret = nilfs_dat_translate(dat, ptr2, &blocknr);
745 				if (ret < 0)
746 					goto out;
747 				ptr2 = blocknr;
748 			}
749 			if (ptr2 != ptr + cnt || ++cnt == maxblocks)
750 				goto end;
751 			index++;
752 		}
753 		if (level == maxlevel)
754 			break;
755 
756 		/* look-up right sibling node */
757 		p.node = nilfs_btree_get_node(btree, path, level + 1, &p.ncmax);
758 		p.index = path[level + 1].bp_index + 1;
759 		p.max_ra_blocks = 7;
760 		if (p.index >= nilfs_btree_node_get_nchildren(p.node) ||
761 		    nilfs_btree_node_get_key(p.node, p.index) != key + cnt)
762 			break;
763 		ptr2 = nilfs_btree_node_get_ptr(p.node, p.index, p.ncmax);
764 		path[level + 1].bp_index = p.index;
765 
766 		brelse(path[level].bp_bh);
767 		path[level].bp_bh = NULL;
768 
769 		ret = __nilfs_btree_get_block(btree, ptr2, &path[level].bp_bh,
770 					      &p);
771 		if (ret < 0)
772 			goto out;
773 		node = nilfs_btree_get_nonroot_node(path, level);
774 		ncmax = nilfs_btree_nchildren_per_block(btree);
775 		index = 0;
776 		path[level].bp_index = index;
777 	}
778  end:
779 	*ptrp = ptr;
780 	ret = cnt;
781  out:
782 	nilfs_btree_free_path(path);
783 	return ret;
784 }
785 
786 static void nilfs_btree_promote_key(struct nilfs_bmap *btree,
787 				    struct nilfs_btree_path *path,
788 				    int level, __u64 key)
789 {
790 	if (level < nilfs_btree_height(btree) - 1) {
791 		do {
792 			nilfs_btree_node_set_key(
793 				nilfs_btree_get_nonroot_node(path, level),
794 				path[level].bp_index, key);
795 			if (!buffer_dirty(path[level].bp_bh))
796 				mark_buffer_dirty(path[level].bp_bh);
797 		} while ((path[level].bp_index == 0) &&
798 			 (++level < nilfs_btree_height(btree) - 1));
799 	}
800 
801 	/* root */
802 	if (level == nilfs_btree_height(btree) - 1) {
803 		nilfs_btree_node_set_key(nilfs_btree_get_root(btree),
804 					 path[level].bp_index, key);
805 	}
806 }
807 
808 static void nilfs_btree_do_insert(struct nilfs_bmap *btree,
809 				  struct nilfs_btree_path *path,
810 				  int level, __u64 *keyp, __u64 *ptrp)
811 {
812 	struct nilfs_btree_node *node;
813 	int ncblk;
814 
815 	if (level < nilfs_btree_height(btree) - 1) {
816 		node = nilfs_btree_get_nonroot_node(path, level);
817 		ncblk = nilfs_btree_nchildren_per_block(btree);
818 		nilfs_btree_node_insert(node, path[level].bp_index,
819 					*keyp, *ptrp, ncblk);
820 		if (!buffer_dirty(path[level].bp_bh))
821 			mark_buffer_dirty(path[level].bp_bh);
822 
823 		if (path[level].bp_index == 0)
824 			nilfs_btree_promote_key(btree, path, level + 1,
825 						nilfs_btree_node_get_key(node,
826 									 0));
827 	} else {
828 		node = nilfs_btree_get_root(btree);
829 		nilfs_btree_node_insert(node, path[level].bp_index,
830 					*keyp, *ptrp,
831 					NILFS_BTREE_ROOT_NCHILDREN_MAX);
832 	}
833 }
834 
835 static void nilfs_btree_carry_left(struct nilfs_bmap *btree,
836 				   struct nilfs_btree_path *path,
837 				   int level, __u64 *keyp, __u64 *ptrp)
838 {
839 	struct nilfs_btree_node *node, *left;
840 	int nchildren, lnchildren, n, move, ncblk;
841 
842 	node = nilfs_btree_get_nonroot_node(path, level);
843 	left = nilfs_btree_get_sib_node(path, level);
844 	nchildren = nilfs_btree_node_get_nchildren(node);
845 	lnchildren = nilfs_btree_node_get_nchildren(left);
846 	ncblk = nilfs_btree_nchildren_per_block(btree);
847 	move = 0;
848 
849 	n = (nchildren + lnchildren + 1) / 2 - lnchildren;
850 	if (n > path[level].bp_index) {
851 		/* move insert point */
852 		n--;
853 		move = 1;
854 	}
855 
856 	nilfs_btree_node_move_left(left, node, n, ncblk, ncblk);
857 
858 	if (!buffer_dirty(path[level].bp_bh))
859 		mark_buffer_dirty(path[level].bp_bh);
860 	if (!buffer_dirty(path[level].bp_sib_bh))
861 		mark_buffer_dirty(path[level].bp_sib_bh);
862 
863 	nilfs_btree_promote_key(btree, path, level + 1,
864 				nilfs_btree_node_get_key(node, 0));
865 
866 	if (move) {
867 		brelse(path[level].bp_bh);
868 		path[level].bp_bh = path[level].bp_sib_bh;
869 		path[level].bp_sib_bh = NULL;
870 		path[level].bp_index += lnchildren;
871 		path[level + 1].bp_index--;
872 	} else {
873 		brelse(path[level].bp_sib_bh);
874 		path[level].bp_sib_bh = NULL;
875 		path[level].bp_index -= n;
876 	}
877 
878 	nilfs_btree_do_insert(btree, path, level, keyp, ptrp);
879 }
880 
881 static void nilfs_btree_carry_right(struct nilfs_bmap *btree,
882 				    struct nilfs_btree_path *path,
883 				    int level, __u64 *keyp, __u64 *ptrp)
884 {
885 	struct nilfs_btree_node *node, *right;
886 	int nchildren, rnchildren, n, move, ncblk;
887 
888 	node = nilfs_btree_get_nonroot_node(path, level);
889 	right = nilfs_btree_get_sib_node(path, level);
890 	nchildren = nilfs_btree_node_get_nchildren(node);
891 	rnchildren = nilfs_btree_node_get_nchildren(right);
892 	ncblk = nilfs_btree_nchildren_per_block(btree);
893 	move = 0;
894 
895 	n = (nchildren + rnchildren + 1) / 2 - rnchildren;
896 	if (n > nchildren - path[level].bp_index) {
897 		/* move insert point */
898 		n--;
899 		move = 1;
900 	}
901 
902 	nilfs_btree_node_move_right(node, right, n, ncblk, ncblk);
903 
904 	if (!buffer_dirty(path[level].bp_bh))
905 		mark_buffer_dirty(path[level].bp_bh);
906 	if (!buffer_dirty(path[level].bp_sib_bh))
907 		mark_buffer_dirty(path[level].bp_sib_bh);
908 
909 	path[level + 1].bp_index++;
910 	nilfs_btree_promote_key(btree, path, level + 1,
911 				nilfs_btree_node_get_key(right, 0));
912 	path[level + 1].bp_index--;
913 
914 	if (move) {
915 		brelse(path[level].bp_bh);
916 		path[level].bp_bh = path[level].bp_sib_bh;
917 		path[level].bp_sib_bh = NULL;
918 		path[level].bp_index -= nilfs_btree_node_get_nchildren(node);
919 		path[level + 1].bp_index++;
920 	} else {
921 		brelse(path[level].bp_sib_bh);
922 		path[level].bp_sib_bh = NULL;
923 	}
924 
925 	nilfs_btree_do_insert(btree, path, level, keyp, ptrp);
926 }
927 
928 static void nilfs_btree_split(struct nilfs_bmap *btree,
929 			      struct nilfs_btree_path *path,
930 			      int level, __u64 *keyp, __u64 *ptrp)
931 {
932 	struct nilfs_btree_node *node, *right;
933 	int nchildren, n, move, ncblk;
934 
935 	node = nilfs_btree_get_nonroot_node(path, level);
936 	right = nilfs_btree_get_sib_node(path, level);
937 	nchildren = nilfs_btree_node_get_nchildren(node);
938 	ncblk = nilfs_btree_nchildren_per_block(btree);
939 	move = 0;
940 
941 	n = (nchildren + 1) / 2;
942 	if (n > nchildren - path[level].bp_index) {
943 		n--;
944 		move = 1;
945 	}
946 
947 	nilfs_btree_node_move_right(node, right, n, ncblk, ncblk);
948 
949 	if (!buffer_dirty(path[level].bp_bh))
950 		mark_buffer_dirty(path[level].bp_bh);
951 	if (!buffer_dirty(path[level].bp_sib_bh))
952 		mark_buffer_dirty(path[level].bp_sib_bh);
953 
954 	if (move) {
955 		path[level].bp_index -= nilfs_btree_node_get_nchildren(node);
956 		nilfs_btree_node_insert(right, path[level].bp_index,
957 					*keyp, *ptrp, ncblk);
958 
959 		*keyp = nilfs_btree_node_get_key(right, 0);
960 		*ptrp = path[level].bp_newreq.bpr_ptr;
961 
962 		brelse(path[level].bp_bh);
963 		path[level].bp_bh = path[level].bp_sib_bh;
964 		path[level].bp_sib_bh = NULL;
965 	} else {
966 		nilfs_btree_do_insert(btree, path, level, keyp, ptrp);
967 
968 		*keyp = nilfs_btree_node_get_key(right, 0);
969 		*ptrp = path[level].bp_newreq.bpr_ptr;
970 
971 		brelse(path[level].bp_sib_bh);
972 		path[level].bp_sib_bh = NULL;
973 	}
974 
975 	path[level + 1].bp_index++;
976 }
977 
978 static void nilfs_btree_grow(struct nilfs_bmap *btree,
979 			     struct nilfs_btree_path *path,
980 			     int level, __u64 *keyp, __u64 *ptrp)
981 {
982 	struct nilfs_btree_node *root, *child;
983 	int n, ncblk;
984 
985 	root = nilfs_btree_get_root(btree);
986 	child = nilfs_btree_get_sib_node(path, level);
987 	ncblk = nilfs_btree_nchildren_per_block(btree);
988 
989 	n = nilfs_btree_node_get_nchildren(root);
990 
991 	nilfs_btree_node_move_right(root, child, n,
992 				    NILFS_BTREE_ROOT_NCHILDREN_MAX, ncblk);
993 	nilfs_btree_node_set_level(root, level + 1);
994 
995 	if (!buffer_dirty(path[level].bp_sib_bh))
996 		mark_buffer_dirty(path[level].bp_sib_bh);
997 
998 	path[level].bp_bh = path[level].bp_sib_bh;
999 	path[level].bp_sib_bh = NULL;
1000 
1001 	nilfs_btree_do_insert(btree, path, level, keyp, ptrp);
1002 
1003 	*keyp = nilfs_btree_node_get_key(child, 0);
1004 	*ptrp = path[level].bp_newreq.bpr_ptr;
1005 }
1006 
1007 static __u64 nilfs_btree_find_near(const struct nilfs_bmap *btree,
1008 				   const struct nilfs_btree_path *path)
1009 {
1010 	struct nilfs_btree_node *node;
1011 	int level, ncmax;
1012 
1013 	if (path == NULL)
1014 		return NILFS_BMAP_INVALID_PTR;
1015 
1016 	/* left sibling */
1017 	level = NILFS_BTREE_LEVEL_NODE_MIN;
1018 	if (path[level].bp_index > 0) {
1019 		node = nilfs_btree_get_node(btree, path, level, &ncmax);
1020 		return nilfs_btree_node_get_ptr(node,
1021 						path[level].bp_index - 1,
1022 						ncmax);
1023 	}
1024 
1025 	/* parent */
1026 	level = NILFS_BTREE_LEVEL_NODE_MIN + 1;
1027 	if (level <= nilfs_btree_height(btree) - 1) {
1028 		node = nilfs_btree_get_node(btree, path, level, &ncmax);
1029 		return nilfs_btree_node_get_ptr(node, path[level].bp_index,
1030 						ncmax);
1031 	}
1032 
1033 	return NILFS_BMAP_INVALID_PTR;
1034 }
1035 
1036 static __u64 nilfs_btree_find_target_v(const struct nilfs_bmap *btree,
1037 				       const struct nilfs_btree_path *path,
1038 				       __u64 key)
1039 {
1040 	__u64 ptr;
1041 
1042 	ptr = nilfs_bmap_find_target_seq(btree, key);
1043 	if (ptr != NILFS_BMAP_INVALID_PTR)
1044 		/* sequential access */
1045 		return ptr;
1046 
1047 	ptr = nilfs_btree_find_near(btree, path);
1048 	if (ptr != NILFS_BMAP_INVALID_PTR)
1049 		/* near */
1050 		return ptr;
1051 
1052 	/* block group */
1053 	return nilfs_bmap_find_target_in_group(btree);
1054 }
1055 
1056 static int nilfs_btree_prepare_insert(struct nilfs_bmap *btree,
1057 				      struct nilfs_btree_path *path,
1058 				      int *levelp, __u64 key, __u64 ptr,
1059 				      struct nilfs_bmap_stats *stats)
1060 {
1061 	struct buffer_head *bh;
1062 	struct nilfs_btree_node *node, *parent, *sib;
1063 	__u64 sibptr;
1064 	int pindex, level, ncmax, ncblk, ret;
1065 	struct inode *dat = NULL;
1066 
1067 	stats->bs_nblocks = 0;
1068 	level = NILFS_BTREE_LEVEL_DATA;
1069 
1070 	/* allocate a new ptr for data block */
1071 	if (NILFS_BMAP_USE_VBN(btree)) {
1072 		path[level].bp_newreq.bpr_ptr =
1073 			nilfs_btree_find_target_v(btree, path, key);
1074 		dat = nilfs_bmap_get_dat(btree);
1075 	}
1076 
1077 	ret = nilfs_bmap_prepare_alloc_ptr(btree, &path[level].bp_newreq, dat);
1078 	if (ret < 0)
1079 		goto err_out_data;
1080 
1081 	ncblk = nilfs_btree_nchildren_per_block(btree);
1082 
1083 	for (level = NILFS_BTREE_LEVEL_NODE_MIN;
1084 	     level < nilfs_btree_height(btree) - 1;
1085 	     level++) {
1086 		node = nilfs_btree_get_nonroot_node(path, level);
1087 		if (nilfs_btree_node_get_nchildren(node) < ncblk) {
1088 			path[level].bp_op = nilfs_btree_do_insert;
1089 			stats->bs_nblocks++;
1090 			goto out;
1091 		}
1092 
1093 		parent = nilfs_btree_get_node(btree, path, level + 1, &ncmax);
1094 		pindex = path[level + 1].bp_index;
1095 
1096 		/* left sibling */
1097 		if (pindex > 0) {
1098 			sibptr = nilfs_btree_node_get_ptr(parent, pindex - 1,
1099 							  ncmax);
1100 			ret = nilfs_btree_get_block(btree, sibptr, &bh);
1101 			if (ret < 0)
1102 				goto err_out_child_node;
1103 			sib = (struct nilfs_btree_node *)bh->b_data;
1104 			if (nilfs_btree_node_get_nchildren(sib) < ncblk) {
1105 				path[level].bp_sib_bh = bh;
1106 				path[level].bp_op = nilfs_btree_carry_left;
1107 				stats->bs_nblocks++;
1108 				goto out;
1109 			} else {
1110 				brelse(bh);
1111 			}
1112 		}
1113 
1114 		/* right sibling */
1115 		if (pindex < nilfs_btree_node_get_nchildren(parent) - 1) {
1116 			sibptr = nilfs_btree_node_get_ptr(parent, pindex + 1,
1117 							  ncmax);
1118 			ret = nilfs_btree_get_block(btree, sibptr, &bh);
1119 			if (ret < 0)
1120 				goto err_out_child_node;
1121 			sib = (struct nilfs_btree_node *)bh->b_data;
1122 			if (nilfs_btree_node_get_nchildren(sib) < ncblk) {
1123 				path[level].bp_sib_bh = bh;
1124 				path[level].bp_op = nilfs_btree_carry_right;
1125 				stats->bs_nblocks++;
1126 				goto out;
1127 			} else {
1128 				brelse(bh);
1129 			}
1130 		}
1131 
1132 		/* split */
1133 		path[level].bp_newreq.bpr_ptr =
1134 			path[level - 1].bp_newreq.bpr_ptr + 1;
1135 		ret = nilfs_bmap_prepare_alloc_ptr(btree,
1136 						   &path[level].bp_newreq, dat);
1137 		if (ret < 0)
1138 			goto err_out_child_node;
1139 		ret = nilfs_btree_get_new_block(btree,
1140 						path[level].bp_newreq.bpr_ptr,
1141 						&bh);
1142 		if (ret < 0)
1143 			goto err_out_curr_node;
1144 
1145 		stats->bs_nblocks++;
1146 
1147 		sib = (struct nilfs_btree_node *)bh->b_data;
1148 		nilfs_btree_node_init(sib, 0, level, 0, ncblk, NULL, NULL);
1149 		path[level].bp_sib_bh = bh;
1150 		path[level].bp_op = nilfs_btree_split;
1151 	}
1152 
1153 	/* root */
1154 	node = nilfs_btree_get_root(btree);
1155 	if (nilfs_btree_node_get_nchildren(node) <
1156 	    NILFS_BTREE_ROOT_NCHILDREN_MAX) {
1157 		path[level].bp_op = nilfs_btree_do_insert;
1158 		stats->bs_nblocks++;
1159 		goto out;
1160 	}
1161 
1162 	/* grow */
1163 	path[level].bp_newreq.bpr_ptr = path[level - 1].bp_newreq.bpr_ptr + 1;
1164 	ret = nilfs_bmap_prepare_alloc_ptr(btree, &path[level].bp_newreq, dat);
1165 	if (ret < 0)
1166 		goto err_out_child_node;
1167 	ret = nilfs_btree_get_new_block(btree, path[level].bp_newreq.bpr_ptr,
1168 					&bh);
1169 	if (ret < 0)
1170 		goto err_out_curr_node;
1171 
1172 	nilfs_btree_node_init((struct nilfs_btree_node *)bh->b_data,
1173 			      0, level, 0, ncblk, NULL, NULL);
1174 	path[level].bp_sib_bh = bh;
1175 	path[level].bp_op = nilfs_btree_grow;
1176 
1177 	level++;
1178 	path[level].bp_op = nilfs_btree_do_insert;
1179 
1180 	/* a newly-created node block and a data block are added */
1181 	stats->bs_nblocks += 2;
1182 
1183 	/* success */
1184  out:
1185 	*levelp = level;
1186 	return ret;
1187 
1188 	/* error */
1189  err_out_curr_node:
1190 	nilfs_bmap_abort_alloc_ptr(btree, &path[level].bp_newreq, dat);
1191  err_out_child_node:
1192 	for (level--; level > NILFS_BTREE_LEVEL_DATA; level--) {
1193 		nilfs_btnode_delete(path[level].bp_sib_bh);
1194 		nilfs_bmap_abort_alloc_ptr(btree, &path[level].bp_newreq, dat);
1195 
1196 	}
1197 
1198 	nilfs_bmap_abort_alloc_ptr(btree, &path[level].bp_newreq, dat);
1199  err_out_data:
1200 	*levelp = level;
1201 	stats->bs_nblocks = 0;
1202 	return ret;
1203 }
1204 
1205 static void nilfs_btree_commit_insert(struct nilfs_bmap *btree,
1206 				      struct nilfs_btree_path *path,
1207 				      int maxlevel, __u64 key, __u64 ptr)
1208 {
1209 	struct inode *dat = NULL;
1210 	int level;
1211 
1212 	set_buffer_nilfs_volatile((struct buffer_head *)((unsigned long)ptr));
1213 	ptr = path[NILFS_BTREE_LEVEL_DATA].bp_newreq.bpr_ptr;
1214 	if (NILFS_BMAP_USE_VBN(btree)) {
1215 		nilfs_bmap_set_target_v(btree, key, ptr);
1216 		dat = nilfs_bmap_get_dat(btree);
1217 	}
1218 
1219 	for (level = NILFS_BTREE_LEVEL_NODE_MIN; level <= maxlevel; level++) {
1220 		nilfs_bmap_commit_alloc_ptr(btree,
1221 					    &path[level - 1].bp_newreq, dat);
1222 		path[level].bp_op(btree, path, level, &key, &ptr);
1223 	}
1224 
1225 	if (!nilfs_bmap_dirty(btree))
1226 		nilfs_bmap_set_dirty(btree);
1227 }
1228 
1229 static int nilfs_btree_insert(struct nilfs_bmap *btree, __u64 key, __u64 ptr)
1230 {
1231 	struct nilfs_btree_path *path;
1232 	struct nilfs_bmap_stats stats;
1233 	int level, ret;
1234 
1235 	path = nilfs_btree_alloc_path();
1236 	if (path == NULL)
1237 		return -ENOMEM;
1238 
1239 	ret = nilfs_btree_do_lookup(btree, path, key, NULL,
1240 				    NILFS_BTREE_LEVEL_NODE_MIN, 0);
1241 	if (ret != -ENOENT) {
1242 		if (ret == 0)
1243 			ret = -EEXIST;
1244 		goto out;
1245 	}
1246 
1247 	ret = nilfs_btree_prepare_insert(btree, path, &level, key, ptr, &stats);
1248 	if (ret < 0)
1249 		goto out;
1250 	nilfs_btree_commit_insert(btree, path, level, key, ptr);
1251 	nilfs_inode_add_blocks(btree->b_inode, stats.bs_nblocks);
1252 
1253  out:
1254 	nilfs_btree_free_path(path);
1255 	return ret;
1256 }
1257 
1258 static void nilfs_btree_do_delete(struct nilfs_bmap *btree,
1259 				  struct nilfs_btree_path *path,
1260 				  int level, __u64 *keyp, __u64 *ptrp)
1261 {
1262 	struct nilfs_btree_node *node;
1263 	int ncblk;
1264 
1265 	if (level < nilfs_btree_height(btree) - 1) {
1266 		node = nilfs_btree_get_nonroot_node(path, level);
1267 		ncblk = nilfs_btree_nchildren_per_block(btree);
1268 		nilfs_btree_node_delete(node, path[level].bp_index,
1269 					keyp, ptrp, ncblk);
1270 		if (!buffer_dirty(path[level].bp_bh))
1271 			mark_buffer_dirty(path[level].bp_bh);
1272 		if (path[level].bp_index == 0)
1273 			nilfs_btree_promote_key(btree, path, level + 1,
1274 				nilfs_btree_node_get_key(node, 0));
1275 	} else {
1276 		node = nilfs_btree_get_root(btree);
1277 		nilfs_btree_node_delete(node, path[level].bp_index,
1278 					keyp, ptrp,
1279 					NILFS_BTREE_ROOT_NCHILDREN_MAX);
1280 	}
1281 }
1282 
1283 static void nilfs_btree_borrow_left(struct nilfs_bmap *btree,
1284 				    struct nilfs_btree_path *path,
1285 				    int level, __u64 *keyp, __u64 *ptrp)
1286 {
1287 	struct nilfs_btree_node *node, *left;
1288 	int nchildren, lnchildren, n, ncblk;
1289 
1290 	nilfs_btree_do_delete(btree, path, level, keyp, ptrp);
1291 
1292 	node = nilfs_btree_get_nonroot_node(path, level);
1293 	left = nilfs_btree_get_sib_node(path, level);
1294 	nchildren = nilfs_btree_node_get_nchildren(node);
1295 	lnchildren = nilfs_btree_node_get_nchildren(left);
1296 	ncblk = nilfs_btree_nchildren_per_block(btree);
1297 
1298 	n = (nchildren + lnchildren) / 2 - nchildren;
1299 
1300 	nilfs_btree_node_move_right(left, node, n, ncblk, ncblk);
1301 
1302 	if (!buffer_dirty(path[level].bp_bh))
1303 		mark_buffer_dirty(path[level].bp_bh);
1304 	if (!buffer_dirty(path[level].bp_sib_bh))
1305 		mark_buffer_dirty(path[level].bp_sib_bh);
1306 
1307 	nilfs_btree_promote_key(btree, path, level + 1,
1308 				nilfs_btree_node_get_key(node, 0));
1309 
1310 	brelse(path[level].bp_sib_bh);
1311 	path[level].bp_sib_bh = NULL;
1312 	path[level].bp_index += n;
1313 }
1314 
1315 static void nilfs_btree_borrow_right(struct nilfs_bmap *btree,
1316 				     struct nilfs_btree_path *path,
1317 				     int level, __u64 *keyp, __u64 *ptrp)
1318 {
1319 	struct nilfs_btree_node *node, *right;
1320 	int nchildren, rnchildren, n, ncblk;
1321 
1322 	nilfs_btree_do_delete(btree, path, level, keyp, ptrp);
1323 
1324 	node = nilfs_btree_get_nonroot_node(path, level);
1325 	right = nilfs_btree_get_sib_node(path, level);
1326 	nchildren = nilfs_btree_node_get_nchildren(node);
1327 	rnchildren = nilfs_btree_node_get_nchildren(right);
1328 	ncblk = nilfs_btree_nchildren_per_block(btree);
1329 
1330 	n = (nchildren + rnchildren) / 2 - nchildren;
1331 
1332 	nilfs_btree_node_move_left(node, right, n, ncblk, ncblk);
1333 
1334 	if (!buffer_dirty(path[level].bp_bh))
1335 		mark_buffer_dirty(path[level].bp_bh);
1336 	if (!buffer_dirty(path[level].bp_sib_bh))
1337 		mark_buffer_dirty(path[level].bp_sib_bh);
1338 
1339 	path[level + 1].bp_index++;
1340 	nilfs_btree_promote_key(btree, path, level + 1,
1341 				nilfs_btree_node_get_key(right, 0));
1342 	path[level + 1].bp_index--;
1343 
1344 	brelse(path[level].bp_sib_bh);
1345 	path[level].bp_sib_bh = NULL;
1346 }
1347 
1348 static void nilfs_btree_concat_left(struct nilfs_bmap *btree,
1349 				    struct nilfs_btree_path *path,
1350 				    int level, __u64 *keyp, __u64 *ptrp)
1351 {
1352 	struct nilfs_btree_node *node, *left;
1353 	int n, ncblk;
1354 
1355 	nilfs_btree_do_delete(btree, path, level, keyp, ptrp);
1356 
1357 	node = nilfs_btree_get_nonroot_node(path, level);
1358 	left = nilfs_btree_get_sib_node(path, level);
1359 	ncblk = nilfs_btree_nchildren_per_block(btree);
1360 
1361 	n = nilfs_btree_node_get_nchildren(node);
1362 
1363 	nilfs_btree_node_move_left(left, node, n, ncblk, ncblk);
1364 
1365 	if (!buffer_dirty(path[level].bp_sib_bh))
1366 		mark_buffer_dirty(path[level].bp_sib_bh);
1367 
1368 	nilfs_btnode_delete(path[level].bp_bh);
1369 	path[level].bp_bh = path[level].bp_sib_bh;
1370 	path[level].bp_sib_bh = NULL;
1371 	path[level].bp_index += nilfs_btree_node_get_nchildren(left);
1372 }
1373 
1374 static void nilfs_btree_concat_right(struct nilfs_bmap *btree,
1375 				     struct nilfs_btree_path *path,
1376 				     int level, __u64 *keyp, __u64 *ptrp)
1377 {
1378 	struct nilfs_btree_node *node, *right;
1379 	int n, ncblk;
1380 
1381 	nilfs_btree_do_delete(btree, path, level, keyp, ptrp);
1382 
1383 	node = nilfs_btree_get_nonroot_node(path, level);
1384 	right = nilfs_btree_get_sib_node(path, level);
1385 	ncblk = nilfs_btree_nchildren_per_block(btree);
1386 
1387 	n = nilfs_btree_node_get_nchildren(right);
1388 
1389 	nilfs_btree_node_move_left(node, right, n, ncblk, ncblk);
1390 
1391 	if (!buffer_dirty(path[level].bp_bh))
1392 		mark_buffer_dirty(path[level].bp_bh);
1393 
1394 	nilfs_btnode_delete(path[level].bp_sib_bh);
1395 	path[level].bp_sib_bh = NULL;
1396 	path[level + 1].bp_index++;
1397 }
1398 
1399 static void nilfs_btree_shrink(struct nilfs_bmap *btree,
1400 			       struct nilfs_btree_path *path,
1401 			       int level, __u64 *keyp, __u64 *ptrp)
1402 {
1403 	struct nilfs_btree_node *root, *child;
1404 	int n, ncblk;
1405 
1406 	nilfs_btree_do_delete(btree, path, level, keyp, ptrp);
1407 
1408 	root = nilfs_btree_get_root(btree);
1409 	child = nilfs_btree_get_nonroot_node(path, level);
1410 	ncblk = nilfs_btree_nchildren_per_block(btree);
1411 
1412 	nilfs_btree_node_delete(root, 0, NULL, NULL,
1413 				NILFS_BTREE_ROOT_NCHILDREN_MAX);
1414 	nilfs_btree_node_set_level(root, level);
1415 	n = nilfs_btree_node_get_nchildren(child);
1416 	nilfs_btree_node_move_left(root, child, n,
1417 				   NILFS_BTREE_ROOT_NCHILDREN_MAX, ncblk);
1418 
1419 	nilfs_btnode_delete(path[level].bp_bh);
1420 	path[level].bp_bh = NULL;
1421 }
1422 
1423 static void nilfs_btree_nop(struct nilfs_bmap *btree,
1424 			    struct nilfs_btree_path *path,
1425 			    int level, __u64 *keyp, __u64 *ptrp)
1426 {
1427 }
1428 
1429 static int nilfs_btree_prepare_delete(struct nilfs_bmap *btree,
1430 				      struct nilfs_btree_path *path,
1431 				      int *levelp,
1432 				      struct nilfs_bmap_stats *stats,
1433 				      struct inode *dat)
1434 {
1435 	struct buffer_head *bh;
1436 	struct nilfs_btree_node *node, *parent, *sib;
1437 	__u64 sibptr;
1438 	int pindex, dindex, level, ncmin, ncmax, ncblk, ret;
1439 
1440 	ret = 0;
1441 	stats->bs_nblocks = 0;
1442 	ncmin = NILFS_BTREE_NODE_NCHILDREN_MIN(nilfs_btree_node_size(btree));
1443 	ncblk = nilfs_btree_nchildren_per_block(btree);
1444 
1445 	for (level = NILFS_BTREE_LEVEL_NODE_MIN, dindex = path[level].bp_index;
1446 	     level < nilfs_btree_height(btree) - 1;
1447 	     level++) {
1448 		node = nilfs_btree_get_nonroot_node(path, level);
1449 		path[level].bp_oldreq.bpr_ptr =
1450 			nilfs_btree_node_get_ptr(node, dindex, ncblk);
1451 		ret = nilfs_bmap_prepare_end_ptr(btree,
1452 						 &path[level].bp_oldreq, dat);
1453 		if (ret < 0)
1454 			goto err_out_child_node;
1455 
1456 		if (nilfs_btree_node_get_nchildren(node) > ncmin) {
1457 			path[level].bp_op = nilfs_btree_do_delete;
1458 			stats->bs_nblocks++;
1459 			goto out;
1460 		}
1461 
1462 		parent = nilfs_btree_get_node(btree, path, level + 1, &ncmax);
1463 		pindex = path[level + 1].bp_index;
1464 		dindex = pindex;
1465 
1466 		if (pindex > 0) {
1467 			/* left sibling */
1468 			sibptr = nilfs_btree_node_get_ptr(parent, pindex - 1,
1469 							  ncmax);
1470 			ret = nilfs_btree_get_block(btree, sibptr, &bh);
1471 			if (ret < 0)
1472 				goto err_out_curr_node;
1473 			sib = (struct nilfs_btree_node *)bh->b_data;
1474 			if (nilfs_btree_node_get_nchildren(sib) > ncmin) {
1475 				path[level].bp_sib_bh = bh;
1476 				path[level].bp_op = nilfs_btree_borrow_left;
1477 				stats->bs_nblocks++;
1478 				goto out;
1479 			} else {
1480 				path[level].bp_sib_bh = bh;
1481 				path[level].bp_op = nilfs_btree_concat_left;
1482 				stats->bs_nblocks++;
1483 				/* continue; */
1484 			}
1485 		} else if (pindex <
1486 			   nilfs_btree_node_get_nchildren(parent) - 1) {
1487 			/* right sibling */
1488 			sibptr = nilfs_btree_node_get_ptr(parent, pindex + 1,
1489 							  ncmax);
1490 			ret = nilfs_btree_get_block(btree, sibptr, &bh);
1491 			if (ret < 0)
1492 				goto err_out_curr_node;
1493 			sib = (struct nilfs_btree_node *)bh->b_data;
1494 			if (nilfs_btree_node_get_nchildren(sib) > ncmin) {
1495 				path[level].bp_sib_bh = bh;
1496 				path[level].bp_op = nilfs_btree_borrow_right;
1497 				stats->bs_nblocks++;
1498 				goto out;
1499 			} else {
1500 				path[level].bp_sib_bh = bh;
1501 				path[level].bp_op = nilfs_btree_concat_right;
1502 				stats->bs_nblocks++;
1503 				/*
1504 				 * When merging right sibling node
1505 				 * into the current node, pointer to
1506 				 * the right sibling node must be
1507 				 * terminated instead.  The adjustment
1508 				 * below is required for that.
1509 				 */
1510 				dindex = pindex + 1;
1511 				/* continue; */
1512 			}
1513 		} else {
1514 			/* no siblings */
1515 			/* the only child of the root node */
1516 			WARN_ON(level != nilfs_btree_height(btree) - 2);
1517 			if (nilfs_btree_node_get_nchildren(node) - 1 <=
1518 			    NILFS_BTREE_ROOT_NCHILDREN_MAX) {
1519 				path[level].bp_op = nilfs_btree_shrink;
1520 				stats->bs_nblocks += 2;
1521 				level++;
1522 				path[level].bp_op = nilfs_btree_nop;
1523 				goto shrink_root_child;
1524 			} else {
1525 				path[level].bp_op = nilfs_btree_do_delete;
1526 				stats->bs_nblocks++;
1527 				goto out;
1528 			}
1529 		}
1530 	}
1531 
1532 	/* child of the root node is deleted */
1533 	path[level].bp_op = nilfs_btree_do_delete;
1534 	stats->bs_nblocks++;
1535 
1536 shrink_root_child:
1537 	node = nilfs_btree_get_root(btree);
1538 	path[level].bp_oldreq.bpr_ptr =
1539 		nilfs_btree_node_get_ptr(node, dindex,
1540 					 NILFS_BTREE_ROOT_NCHILDREN_MAX);
1541 
1542 	ret = nilfs_bmap_prepare_end_ptr(btree, &path[level].bp_oldreq, dat);
1543 	if (ret < 0)
1544 		goto err_out_child_node;
1545 
1546 	/* success */
1547  out:
1548 	*levelp = level;
1549 	return ret;
1550 
1551 	/* error */
1552  err_out_curr_node:
1553 	nilfs_bmap_abort_end_ptr(btree, &path[level].bp_oldreq, dat);
1554  err_out_child_node:
1555 	for (level--; level >= NILFS_BTREE_LEVEL_NODE_MIN; level--) {
1556 		brelse(path[level].bp_sib_bh);
1557 		nilfs_bmap_abort_end_ptr(btree, &path[level].bp_oldreq, dat);
1558 	}
1559 	*levelp = level;
1560 	stats->bs_nblocks = 0;
1561 	return ret;
1562 }
1563 
1564 static void nilfs_btree_commit_delete(struct nilfs_bmap *btree,
1565 				      struct nilfs_btree_path *path,
1566 				      int maxlevel, struct inode *dat)
1567 {
1568 	int level;
1569 
1570 	for (level = NILFS_BTREE_LEVEL_NODE_MIN; level <= maxlevel; level++) {
1571 		nilfs_bmap_commit_end_ptr(btree, &path[level].bp_oldreq, dat);
1572 		path[level].bp_op(btree, path, level, NULL, NULL);
1573 	}
1574 
1575 	if (!nilfs_bmap_dirty(btree))
1576 		nilfs_bmap_set_dirty(btree);
1577 }
1578 
1579 static int nilfs_btree_delete(struct nilfs_bmap *btree, __u64 key)
1580 
1581 {
1582 	struct nilfs_btree_path *path;
1583 	struct nilfs_bmap_stats stats;
1584 	struct inode *dat;
1585 	int level, ret;
1586 
1587 	path = nilfs_btree_alloc_path();
1588 	if (path == NULL)
1589 		return -ENOMEM;
1590 
1591 	ret = nilfs_btree_do_lookup(btree, path, key, NULL,
1592 				    NILFS_BTREE_LEVEL_NODE_MIN, 0);
1593 	if (ret < 0)
1594 		goto out;
1595 
1596 
1597 	dat = NILFS_BMAP_USE_VBN(btree) ? nilfs_bmap_get_dat(btree) : NULL;
1598 
1599 	ret = nilfs_btree_prepare_delete(btree, path, &level, &stats, dat);
1600 	if (ret < 0)
1601 		goto out;
1602 	nilfs_btree_commit_delete(btree, path, level, dat);
1603 	nilfs_inode_sub_blocks(btree->b_inode, stats.bs_nblocks);
1604 
1605 out:
1606 	nilfs_btree_free_path(path);
1607 	return ret;
1608 }
1609 
1610 static int nilfs_btree_seek_key(const struct nilfs_bmap *btree, __u64 start,
1611 				__u64 *keyp)
1612 {
1613 	struct nilfs_btree_path *path;
1614 	const int minlevel = NILFS_BTREE_LEVEL_NODE_MIN;
1615 	int ret;
1616 
1617 	path = nilfs_btree_alloc_path();
1618 	if (!path)
1619 		return -ENOMEM;
1620 
1621 	ret = nilfs_btree_do_lookup(btree, path, start, NULL, minlevel, 0);
1622 	if (!ret)
1623 		*keyp = start;
1624 	else if (ret == -ENOENT)
1625 		ret = nilfs_btree_get_next_key(btree, path, minlevel, keyp);
1626 
1627 	nilfs_btree_free_path(path);
1628 	return ret;
1629 }
1630 
1631 static int nilfs_btree_last_key(const struct nilfs_bmap *btree, __u64 *keyp)
1632 {
1633 	struct nilfs_btree_path *path;
1634 	int ret;
1635 
1636 	path = nilfs_btree_alloc_path();
1637 	if (path == NULL)
1638 		return -ENOMEM;
1639 
1640 	ret = nilfs_btree_do_lookup_last(btree, path, keyp, NULL);
1641 
1642 	nilfs_btree_free_path(path);
1643 
1644 	return ret;
1645 }
1646 
1647 static int nilfs_btree_check_delete(struct nilfs_bmap *btree, __u64 key)
1648 {
1649 	struct buffer_head *bh;
1650 	struct nilfs_btree_node *root, *node;
1651 	__u64 maxkey, nextmaxkey;
1652 	__u64 ptr;
1653 	int nchildren, ret;
1654 
1655 	root = nilfs_btree_get_root(btree);
1656 	switch (nilfs_btree_height(btree)) {
1657 	case 2:
1658 		bh = NULL;
1659 		node = root;
1660 		break;
1661 	case 3:
1662 		nchildren = nilfs_btree_node_get_nchildren(root);
1663 		if (nchildren > 1)
1664 			return 0;
1665 		ptr = nilfs_btree_node_get_ptr(root, nchildren - 1,
1666 					       NILFS_BTREE_ROOT_NCHILDREN_MAX);
1667 		ret = nilfs_btree_get_block(btree, ptr, &bh);
1668 		if (ret < 0)
1669 			return ret;
1670 		node = (struct nilfs_btree_node *)bh->b_data;
1671 		break;
1672 	default:
1673 		return 0;
1674 	}
1675 
1676 	nchildren = nilfs_btree_node_get_nchildren(node);
1677 	maxkey = nilfs_btree_node_get_key(node, nchildren - 1);
1678 	nextmaxkey = (nchildren > 1) ?
1679 		nilfs_btree_node_get_key(node, nchildren - 2) : 0;
1680 	brelse(bh);
1681 
1682 	return (maxkey == key) && (nextmaxkey < NILFS_BMAP_LARGE_LOW);
1683 }
1684 
1685 static int nilfs_btree_gather_data(struct nilfs_bmap *btree,
1686 				   __u64 *keys, __u64 *ptrs, int nitems)
1687 {
1688 	struct buffer_head *bh;
1689 	struct nilfs_btree_node *node, *root;
1690 	__le64 *dkeys;
1691 	__le64 *dptrs;
1692 	__u64 ptr;
1693 	int nchildren, ncmax, i, ret;
1694 
1695 	root = nilfs_btree_get_root(btree);
1696 	switch (nilfs_btree_height(btree)) {
1697 	case 2:
1698 		bh = NULL;
1699 		node = root;
1700 		ncmax = NILFS_BTREE_ROOT_NCHILDREN_MAX;
1701 		break;
1702 	case 3:
1703 		nchildren = nilfs_btree_node_get_nchildren(root);
1704 		WARN_ON(nchildren > 1);
1705 		ptr = nilfs_btree_node_get_ptr(root, nchildren - 1,
1706 					       NILFS_BTREE_ROOT_NCHILDREN_MAX);
1707 		ret = nilfs_btree_get_block(btree, ptr, &bh);
1708 		if (ret < 0)
1709 			return ret;
1710 		node = (struct nilfs_btree_node *)bh->b_data;
1711 		ncmax = nilfs_btree_nchildren_per_block(btree);
1712 		break;
1713 	default:
1714 		node = NULL;
1715 		return -EINVAL;
1716 	}
1717 
1718 	nchildren = nilfs_btree_node_get_nchildren(node);
1719 	if (nchildren < nitems)
1720 		nitems = nchildren;
1721 	dkeys = nilfs_btree_node_dkeys(node);
1722 	dptrs = nilfs_btree_node_dptrs(node, ncmax);
1723 	for (i = 0; i < nitems; i++) {
1724 		keys[i] = le64_to_cpu(dkeys[i]);
1725 		ptrs[i] = le64_to_cpu(dptrs[i]);
1726 	}
1727 
1728 	brelse(bh);
1729 
1730 	return nitems;
1731 }
1732 
1733 static int
1734 nilfs_btree_prepare_convert_and_insert(struct nilfs_bmap *btree, __u64 key,
1735 				       union nilfs_bmap_ptr_req *dreq,
1736 				       union nilfs_bmap_ptr_req *nreq,
1737 				       struct buffer_head **bhp,
1738 				       struct nilfs_bmap_stats *stats)
1739 {
1740 	struct buffer_head *bh;
1741 	struct inode *dat = NULL;
1742 	int ret;
1743 
1744 	stats->bs_nblocks = 0;
1745 
1746 	/* for data */
1747 	/* cannot find near ptr */
1748 	if (NILFS_BMAP_USE_VBN(btree)) {
1749 		dreq->bpr_ptr = nilfs_btree_find_target_v(btree, NULL, key);
1750 		dat = nilfs_bmap_get_dat(btree);
1751 	}
1752 
1753 	ret = nilfs_attach_btree_node_cache(&NILFS_BMAP_I(btree)->vfs_inode);
1754 	if (ret < 0)
1755 		return ret;
1756 
1757 	ret = nilfs_bmap_prepare_alloc_ptr(btree, dreq, dat);
1758 	if (ret < 0)
1759 		return ret;
1760 
1761 	*bhp = NULL;
1762 	stats->bs_nblocks++;
1763 	if (nreq != NULL) {
1764 		nreq->bpr_ptr = dreq->bpr_ptr + 1;
1765 		ret = nilfs_bmap_prepare_alloc_ptr(btree, nreq, dat);
1766 		if (ret < 0)
1767 			goto err_out_dreq;
1768 
1769 		ret = nilfs_btree_get_new_block(btree, nreq->bpr_ptr, &bh);
1770 		if (ret < 0)
1771 			goto err_out_nreq;
1772 
1773 		*bhp = bh;
1774 		stats->bs_nblocks++;
1775 	}
1776 
1777 	/* success */
1778 	return 0;
1779 
1780 	/* error */
1781  err_out_nreq:
1782 	nilfs_bmap_abort_alloc_ptr(btree, nreq, dat);
1783  err_out_dreq:
1784 	nilfs_bmap_abort_alloc_ptr(btree, dreq, dat);
1785 	stats->bs_nblocks = 0;
1786 	return ret;
1787 
1788 }
1789 
1790 static void
1791 nilfs_btree_commit_convert_and_insert(struct nilfs_bmap *btree,
1792 				      __u64 key, __u64 ptr,
1793 				      const __u64 *keys, const __u64 *ptrs,
1794 				      int n,
1795 				      union nilfs_bmap_ptr_req *dreq,
1796 				      union nilfs_bmap_ptr_req *nreq,
1797 				      struct buffer_head *bh)
1798 {
1799 	struct nilfs_btree_node *node;
1800 	struct inode *dat;
1801 	__u64 tmpptr;
1802 	int ncblk;
1803 
1804 	/* free resources */
1805 	if (btree->b_ops->bop_clear != NULL)
1806 		btree->b_ops->bop_clear(btree);
1807 
1808 	/* ptr must be a pointer to a buffer head. */
1809 	set_buffer_nilfs_volatile((struct buffer_head *)((unsigned long)ptr));
1810 
1811 	/* convert and insert */
1812 	dat = NILFS_BMAP_USE_VBN(btree) ? nilfs_bmap_get_dat(btree) : NULL;
1813 	__nilfs_btree_init(btree);
1814 	if (nreq != NULL) {
1815 		nilfs_bmap_commit_alloc_ptr(btree, dreq, dat);
1816 		nilfs_bmap_commit_alloc_ptr(btree, nreq, dat);
1817 
1818 		/* create child node at level 1 */
1819 		node = (struct nilfs_btree_node *)bh->b_data;
1820 		ncblk = nilfs_btree_nchildren_per_block(btree);
1821 		nilfs_btree_node_init(node, 0, 1, n, ncblk, keys, ptrs);
1822 		nilfs_btree_node_insert(node, n, key, dreq->bpr_ptr, ncblk);
1823 		if (!buffer_dirty(bh))
1824 			mark_buffer_dirty(bh);
1825 		if (!nilfs_bmap_dirty(btree))
1826 			nilfs_bmap_set_dirty(btree);
1827 
1828 		brelse(bh);
1829 
1830 		/* create root node at level 2 */
1831 		node = nilfs_btree_get_root(btree);
1832 		tmpptr = nreq->bpr_ptr;
1833 		nilfs_btree_node_init(node, NILFS_BTREE_NODE_ROOT, 2, 1,
1834 				      NILFS_BTREE_ROOT_NCHILDREN_MAX,
1835 				      &keys[0], &tmpptr);
1836 	} else {
1837 		nilfs_bmap_commit_alloc_ptr(btree, dreq, dat);
1838 
1839 		/* create root node at level 1 */
1840 		node = nilfs_btree_get_root(btree);
1841 		nilfs_btree_node_init(node, NILFS_BTREE_NODE_ROOT, 1, n,
1842 				      NILFS_BTREE_ROOT_NCHILDREN_MAX,
1843 				      keys, ptrs);
1844 		nilfs_btree_node_insert(node, n, key, dreq->bpr_ptr,
1845 					NILFS_BTREE_ROOT_NCHILDREN_MAX);
1846 		if (!nilfs_bmap_dirty(btree))
1847 			nilfs_bmap_set_dirty(btree);
1848 	}
1849 
1850 	if (NILFS_BMAP_USE_VBN(btree))
1851 		nilfs_bmap_set_target_v(btree, key, dreq->bpr_ptr);
1852 }
1853 
1854 /**
1855  * nilfs_btree_convert_and_insert -
1856  * @bmap:
1857  * @key:
1858  * @ptr:
1859  * @keys:
1860  * @ptrs:
1861  * @n:
1862  */
1863 int nilfs_btree_convert_and_insert(struct nilfs_bmap *btree,
1864 				   __u64 key, __u64 ptr,
1865 				   const __u64 *keys, const __u64 *ptrs, int n)
1866 {
1867 	struct buffer_head *bh = NULL;
1868 	union nilfs_bmap_ptr_req dreq, nreq, *di, *ni;
1869 	struct nilfs_bmap_stats stats;
1870 	int ret;
1871 
1872 	if (n + 1 <= NILFS_BTREE_ROOT_NCHILDREN_MAX) {
1873 		di = &dreq;
1874 		ni = NULL;
1875 	} else if ((n + 1) <= NILFS_BTREE_NODE_NCHILDREN_MAX(
1876 			   nilfs_btree_node_size(btree))) {
1877 		di = &dreq;
1878 		ni = &nreq;
1879 	} else {
1880 		di = NULL;
1881 		ni = NULL;
1882 		BUG();
1883 	}
1884 
1885 	ret = nilfs_btree_prepare_convert_and_insert(btree, key, di, ni, &bh,
1886 						     &stats);
1887 	if (ret < 0)
1888 		return ret;
1889 	nilfs_btree_commit_convert_and_insert(btree, key, ptr, keys, ptrs, n,
1890 					      di, ni, bh);
1891 	nilfs_inode_add_blocks(btree->b_inode, stats.bs_nblocks);
1892 	return 0;
1893 }
1894 
1895 static int nilfs_btree_propagate_p(struct nilfs_bmap *btree,
1896 				   struct nilfs_btree_path *path,
1897 				   int level,
1898 				   struct buffer_head *bh)
1899 {
1900 	while ((++level < nilfs_btree_height(btree) - 1) &&
1901 	       !buffer_dirty(path[level].bp_bh))
1902 		mark_buffer_dirty(path[level].bp_bh);
1903 
1904 	return 0;
1905 }
1906 
1907 static int nilfs_btree_prepare_update_v(struct nilfs_bmap *btree,
1908 					struct nilfs_btree_path *path,
1909 					int level, struct inode *dat)
1910 {
1911 	struct nilfs_btree_node *parent;
1912 	int ncmax, ret;
1913 
1914 	parent = nilfs_btree_get_node(btree, path, level + 1, &ncmax);
1915 	path[level].bp_oldreq.bpr_ptr =
1916 		nilfs_btree_node_get_ptr(parent, path[level + 1].bp_index,
1917 					 ncmax);
1918 	path[level].bp_newreq.bpr_ptr = path[level].bp_oldreq.bpr_ptr + 1;
1919 	ret = nilfs_dat_prepare_update(dat, &path[level].bp_oldreq.bpr_req,
1920 				       &path[level].bp_newreq.bpr_req);
1921 	if (ret < 0)
1922 		return ret;
1923 
1924 	if (buffer_nilfs_node(path[level].bp_bh)) {
1925 		path[level].bp_ctxt.oldkey = path[level].bp_oldreq.bpr_ptr;
1926 		path[level].bp_ctxt.newkey = path[level].bp_newreq.bpr_ptr;
1927 		path[level].bp_ctxt.bh = path[level].bp_bh;
1928 		ret = nilfs_btnode_prepare_change_key(
1929 			NILFS_BMAP_I(btree)->i_assoc_inode->i_mapping,
1930 			&path[level].bp_ctxt);
1931 		if (ret < 0) {
1932 			nilfs_dat_abort_update(dat,
1933 					       &path[level].bp_oldreq.bpr_req,
1934 					       &path[level].bp_newreq.bpr_req);
1935 			return ret;
1936 		}
1937 	}
1938 
1939 	return 0;
1940 }
1941 
1942 static void nilfs_btree_commit_update_v(struct nilfs_bmap *btree,
1943 					struct nilfs_btree_path *path,
1944 					int level, struct inode *dat)
1945 {
1946 	struct nilfs_btree_node *parent;
1947 	int ncmax;
1948 
1949 	nilfs_dat_commit_update(dat, &path[level].bp_oldreq.bpr_req,
1950 				&path[level].bp_newreq.bpr_req,
1951 				btree->b_ptr_type == NILFS_BMAP_PTR_VS);
1952 
1953 	if (buffer_nilfs_node(path[level].bp_bh)) {
1954 		nilfs_btnode_commit_change_key(
1955 			NILFS_BMAP_I(btree)->i_assoc_inode->i_mapping,
1956 			&path[level].bp_ctxt);
1957 		path[level].bp_bh = path[level].bp_ctxt.bh;
1958 	}
1959 	set_buffer_nilfs_volatile(path[level].bp_bh);
1960 
1961 	parent = nilfs_btree_get_node(btree, path, level + 1, &ncmax);
1962 	nilfs_btree_node_set_ptr(parent, path[level + 1].bp_index,
1963 				 path[level].bp_newreq.bpr_ptr, ncmax);
1964 }
1965 
1966 static void nilfs_btree_abort_update_v(struct nilfs_bmap *btree,
1967 				       struct nilfs_btree_path *path,
1968 				       int level, struct inode *dat)
1969 {
1970 	nilfs_dat_abort_update(dat, &path[level].bp_oldreq.bpr_req,
1971 			       &path[level].bp_newreq.bpr_req);
1972 	if (buffer_nilfs_node(path[level].bp_bh))
1973 		nilfs_btnode_abort_change_key(
1974 			NILFS_BMAP_I(btree)->i_assoc_inode->i_mapping,
1975 			&path[level].bp_ctxt);
1976 }
1977 
1978 static int nilfs_btree_prepare_propagate_v(struct nilfs_bmap *btree,
1979 					   struct nilfs_btree_path *path,
1980 					   int minlevel, int *maxlevelp,
1981 					   struct inode *dat)
1982 {
1983 	int level, ret;
1984 
1985 	level = minlevel;
1986 	if (!buffer_nilfs_volatile(path[level].bp_bh)) {
1987 		ret = nilfs_btree_prepare_update_v(btree, path, level, dat);
1988 		if (ret < 0)
1989 			return ret;
1990 	}
1991 	while ((++level < nilfs_btree_height(btree) - 1) &&
1992 	       !buffer_dirty(path[level].bp_bh)) {
1993 
1994 		WARN_ON(buffer_nilfs_volatile(path[level].bp_bh));
1995 		ret = nilfs_btree_prepare_update_v(btree, path, level, dat);
1996 		if (ret < 0)
1997 			goto out;
1998 	}
1999 
2000 	/* success */
2001 	*maxlevelp = level - 1;
2002 	return 0;
2003 
2004 	/* error */
2005  out:
2006 	while (--level > minlevel)
2007 		nilfs_btree_abort_update_v(btree, path, level, dat);
2008 	if (!buffer_nilfs_volatile(path[level].bp_bh))
2009 		nilfs_btree_abort_update_v(btree, path, level, dat);
2010 	return ret;
2011 }
2012 
2013 static void nilfs_btree_commit_propagate_v(struct nilfs_bmap *btree,
2014 					   struct nilfs_btree_path *path,
2015 					   int minlevel, int maxlevel,
2016 					   struct buffer_head *bh,
2017 					   struct inode *dat)
2018 {
2019 	int level;
2020 
2021 	if (!buffer_nilfs_volatile(path[minlevel].bp_bh))
2022 		nilfs_btree_commit_update_v(btree, path, minlevel, dat);
2023 
2024 	for (level = minlevel + 1; level <= maxlevel; level++)
2025 		nilfs_btree_commit_update_v(btree, path, level, dat);
2026 }
2027 
2028 static int nilfs_btree_propagate_v(struct nilfs_bmap *btree,
2029 				   struct nilfs_btree_path *path,
2030 				   int level, struct buffer_head *bh)
2031 {
2032 	int maxlevel = 0, ret;
2033 	struct nilfs_btree_node *parent;
2034 	struct inode *dat = nilfs_bmap_get_dat(btree);
2035 	__u64 ptr;
2036 	int ncmax;
2037 
2038 	get_bh(bh);
2039 	path[level].bp_bh = bh;
2040 	ret = nilfs_btree_prepare_propagate_v(btree, path, level, &maxlevel,
2041 					      dat);
2042 	if (ret < 0)
2043 		goto out;
2044 
2045 	if (buffer_nilfs_volatile(path[level].bp_bh)) {
2046 		parent = nilfs_btree_get_node(btree, path, level + 1, &ncmax);
2047 		ptr = nilfs_btree_node_get_ptr(parent,
2048 					       path[level + 1].bp_index,
2049 					       ncmax);
2050 		ret = nilfs_dat_mark_dirty(dat, ptr);
2051 		if (ret < 0)
2052 			goto out;
2053 	}
2054 
2055 	nilfs_btree_commit_propagate_v(btree, path, level, maxlevel, bh, dat);
2056 
2057  out:
2058 	brelse(path[level].bp_bh);
2059 	path[level].bp_bh = NULL;
2060 	return ret;
2061 }
2062 
2063 static int nilfs_btree_propagate(struct nilfs_bmap *btree,
2064 				 struct buffer_head *bh)
2065 {
2066 	struct nilfs_btree_path *path;
2067 	struct nilfs_btree_node *node;
2068 	__u64 key;
2069 	int level, ret;
2070 
2071 	WARN_ON(!buffer_dirty(bh));
2072 
2073 	path = nilfs_btree_alloc_path();
2074 	if (path == NULL)
2075 		return -ENOMEM;
2076 
2077 	if (buffer_nilfs_node(bh)) {
2078 		node = (struct nilfs_btree_node *)bh->b_data;
2079 		key = nilfs_btree_node_get_key(node, 0);
2080 		level = nilfs_btree_node_get_level(node);
2081 	} else {
2082 		key = nilfs_bmap_data_get_key(btree, bh);
2083 		level = NILFS_BTREE_LEVEL_DATA;
2084 	}
2085 
2086 	ret = nilfs_btree_do_lookup(btree, path, key, NULL, level + 1, 0);
2087 	if (ret < 0) {
2088 		if (unlikely(ret == -ENOENT))
2089 			nilfs_crit(btree->b_inode->i_sb,
2090 				   "writing node/leaf block does not appear in b-tree (ino=%lu) at key=%llu, level=%d",
2091 				   btree->b_inode->i_ino,
2092 				   (unsigned long long)key, level);
2093 		goto out;
2094 	}
2095 
2096 	ret = NILFS_BMAP_USE_VBN(btree) ?
2097 		nilfs_btree_propagate_v(btree, path, level, bh) :
2098 		nilfs_btree_propagate_p(btree, path, level, bh);
2099 
2100  out:
2101 	nilfs_btree_free_path(path);
2102 
2103 	return ret;
2104 }
2105 
2106 static int nilfs_btree_propagate_gc(struct nilfs_bmap *btree,
2107 				    struct buffer_head *bh)
2108 {
2109 	return nilfs_dat_mark_dirty(nilfs_bmap_get_dat(btree), bh->b_blocknr);
2110 }
2111 
2112 static void nilfs_btree_add_dirty_buffer(struct nilfs_bmap *btree,
2113 					 struct list_head *lists,
2114 					 struct buffer_head *bh)
2115 {
2116 	struct list_head *head;
2117 	struct buffer_head *cbh;
2118 	struct nilfs_btree_node *node, *cnode;
2119 	__u64 key, ckey;
2120 	int level;
2121 
2122 	get_bh(bh);
2123 	node = (struct nilfs_btree_node *)bh->b_data;
2124 	key = nilfs_btree_node_get_key(node, 0);
2125 	level = nilfs_btree_node_get_level(node);
2126 	if (level < NILFS_BTREE_LEVEL_NODE_MIN ||
2127 	    level >= NILFS_BTREE_LEVEL_MAX) {
2128 		dump_stack();
2129 		nilfs_warn(btree->b_inode->i_sb,
2130 			   "invalid btree level: %d (key=%llu, ino=%lu, blocknr=%llu)",
2131 			   level, (unsigned long long)key,
2132 			   btree->b_inode->i_ino,
2133 			   (unsigned long long)bh->b_blocknr);
2134 		return;
2135 	}
2136 
2137 	list_for_each(head, &lists[level]) {
2138 		cbh = list_entry(head, struct buffer_head, b_assoc_buffers);
2139 		cnode = (struct nilfs_btree_node *)cbh->b_data;
2140 		ckey = nilfs_btree_node_get_key(cnode, 0);
2141 		if (key < ckey)
2142 			break;
2143 	}
2144 	list_add_tail(&bh->b_assoc_buffers, head);
2145 }
2146 
2147 static void nilfs_btree_lookup_dirty_buffers(struct nilfs_bmap *btree,
2148 					     struct list_head *listp)
2149 {
2150 	struct inode *btnc_inode = NILFS_BMAP_I(btree)->i_assoc_inode;
2151 	struct address_space *btcache = btnc_inode->i_mapping;
2152 	struct list_head lists[NILFS_BTREE_LEVEL_MAX];
2153 	struct folio_batch fbatch;
2154 	struct buffer_head *bh, *head;
2155 	pgoff_t index = 0;
2156 	int level, i;
2157 
2158 	for (level = NILFS_BTREE_LEVEL_NODE_MIN;
2159 	     level < NILFS_BTREE_LEVEL_MAX;
2160 	     level++)
2161 		INIT_LIST_HEAD(&lists[level]);
2162 
2163 	folio_batch_init(&fbatch);
2164 
2165 	while (filemap_get_folios_tag(btcache, &index, (pgoff_t)-1,
2166 				PAGECACHE_TAG_DIRTY, &fbatch)) {
2167 		for (i = 0; i < folio_batch_count(&fbatch); i++) {
2168 			bh = head = folio_buffers(fbatch.folios[i]);
2169 			do {
2170 				if (buffer_dirty(bh))
2171 					nilfs_btree_add_dirty_buffer(btree,
2172 								     lists, bh);
2173 			} while ((bh = bh->b_this_page) != head);
2174 		}
2175 		folio_batch_release(&fbatch);
2176 		cond_resched();
2177 	}
2178 
2179 	for (level = NILFS_BTREE_LEVEL_NODE_MIN;
2180 	     level < NILFS_BTREE_LEVEL_MAX;
2181 	     level++)
2182 		list_splice_tail(&lists[level], listp);
2183 }
2184 
2185 static int nilfs_btree_assign_p(struct nilfs_bmap *btree,
2186 				struct nilfs_btree_path *path,
2187 				int level,
2188 				struct buffer_head **bh,
2189 				sector_t blocknr,
2190 				union nilfs_binfo *binfo)
2191 {
2192 	struct nilfs_btree_node *parent;
2193 	__u64 key;
2194 	__u64 ptr;
2195 	int ncmax, ret;
2196 
2197 	parent = nilfs_btree_get_node(btree, path, level + 1, &ncmax);
2198 	ptr = nilfs_btree_node_get_ptr(parent, path[level + 1].bp_index,
2199 				       ncmax);
2200 	if (buffer_nilfs_node(*bh)) {
2201 		path[level].bp_ctxt.oldkey = ptr;
2202 		path[level].bp_ctxt.newkey = blocknr;
2203 		path[level].bp_ctxt.bh = *bh;
2204 		ret = nilfs_btnode_prepare_change_key(
2205 			NILFS_BMAP_I(btree)->i_assoc_inode->i_mapping,
2206 			&path[level].bp_ctxt);
2207 		if (ret < 0)
2208 			return ret;
2209 		nilfs_btnode_commit_change_key(
2210 			NILFS_BMAP_I(btree)->i_assoc_inode->i_mapping,
2211 			&path[level].bp_ctxt);
2212 		*bh = path[level].bp_ctxt.bh;
2213 	}
2214 
2215 	nilfs_btree_node_set_ptr(parent, path[level + 1].bp_index, blocknr,
2216 				 ncmax);
2217 
2218 	key = nilfs_btree_node_get_key(parent, path[level + 1].bp_index);
2219 	/* on-disk format */
2220 	binfo->bi_dat.bi_blkoff = cpu_to_le64(key);
2221 	binfo->bi_dat.bi_level = level;
2222 	memset(binfo->bi_dat.bi_pad, 0, sizeof(binfo->bi_dat.bi_pad));
2223 
2224 	return 0;
2225 }
2226 
2227 static int nilfs_btree_assign_v(struct nilfs_bmap *btree,
2228 				struct nilfs_btree_path *path,
2229 				int level,
2230 				struct buffer_head **bh,
2231 				sector_t blocknr,
2232 				union nilfs_binfo *binfo)
2233 {
2234 	struct nilfs_btree_node *parent;
2235 	struct inode *dat = nilfs_bmap_get_dat(btree);
2236 	__u64 key;
2237 	__u64 ptr;
2238 	union nilfs_bmap_ptr_req req;
2239 	int ncmax, ret;
2240 
2241 	parent = nilfs_btree_get_node(btree, path, level + 1, &ncmax);
2242 	ptr = nilfs_btree_node_get_ptr(parent, path[level + 1].bp_index,
2243 				       ncmax);
2244 	req.bpr_ptr = ptr;
2245 	ret = nilfs_dat_prepare_start(dat, &req.bpr_req);
2246 	if (ret < 0)
2247 		return ret;
2248 	nilfs_dat_commit_start(dat, &req.bpr_req, blocknr);
2249 
2250 	key = nilfs_btree_node_get_key(parent, path[level + 1].bp_index);
2251 	/* on-disk format */
2252 	binfo->bi_v.bi_vblocknr = cpu_to_le64(ptr);
2253 	binfo->bi_v.bi_blkoff = cpu_to_le64(key);
2254 
2255 	return 0;
2256 }
2257 
2258 static int nilfs_btree_assign(struct nilfs_bmap *btree,
2259 			      struct buffer_head **bh,
2260 			      sector_t blocknr,
2261 			      union nilfs_binfo *binfo)
2262 {
2263 	struct nilfs_btree_path *path;
2264 	struct nilfs_btree_node *node;
2265 	__u64 key;
2266 	int level, ret;
2267 
2268 	path = nilfs_btree_alloc_path();
2269 	if (path == NULL)
2270 		return -ENOMEM;
2271 
2272 	if (buffer_nilfs_node(*bh)) {
2273 		node = (struct nilfs_btree_node *)(*bh)->b_data;
2274 		key = nilfs_btree_node_get_key(node, 0);
2275 		level = nilfs_btree_node_get_level(node);
2276 	} else {
2277 		key = nilfs_bmap_data_get_key(btree, *bh);
2278 		level = NILFS_BTREE_LEVEL_DATA;
2279 	}
2280 
2281 	ret = nilfs_btree_do_lookup(btree, path, key, NULL, level + 1, 0);
2282 	if (ret < 0) {
2283 		WARN_ON(ret == -ENOENT);
2284 		goto out;
2285 	}
2286 
2287 	ret = NILFS_BMAP_USE_VBN(btree) ?
2288 		nilfs_btree_assign_v(btree, path, level, bh, blocknr, binfo) :
2289 		nilfs_btree_assign_p(btree, path, level, bh, blocknr, binfo);
2290 
2291  out:
2292 	nilfs_btree_free_path(path);
2293 
2294 	return ret;
2295 }
2296 
2297 static int nilfs_btree_assign_gc(struct nilfs_bmap *btree,
2298 				 struct buffer_head **bh,
2299 				 sector_t blocknr,
2300 				 union nilfs_binfo *binfo)
2301 {
2302 	struct nilfs_btree_node *node;
2303 	__u64 key;
2304 	int ret;
2305 
2306 	ret = nilfs_dat_move(nilfs_bmap_get_dat(btree), (*bh)->b_blocknr,
2307 			     blocknr);
2308 	if (ret < 0)
2309 		return ret;
2310 
2311 	if (buffer_nilfs_node(*bh)) {
2312 		node = (struct nilfs_btree_node *)(*bh)->b_data;
2313 		key = nilfs_btree_node_get_key(node, 0);
2314 	} else
2315 		key = nilfs_bmap_data_get_key(btree, *bh);
2316 
2317 	/* on-disk format */
2318 	binfo->bi_v.bi_vblocknr = cpu_to_le64((*bh)->b_blocknr);
2319 	binfo->bi_v.bi_blkoff = cpu_to_le64(key);
2320 
2321 	return 0;
2322 }
2323 
2324 static int nilfs_btree_mark(struct nilfs_bmap *btree, __u64 key, int level)
2325 {
2326 	struct buffer_head *bh;
2327 	struct nilfs_btree_path *path;
2328 	__u64 ptr;
2329 	int ret;
2330 
2331 	path = nilfs_btree_alloc_path();
2332 	if (path == NULL)
2333 		return -ENOMEM;
2334 
2335 	ret = nilfs_btree_do_lookup(btree, path, key, &ptr, level + 1, 0);
2336 	if (ret < 0) {
2337 		WARN_ON(ret == -ENOENT);
2338 		goto out;
2339 	}
2340 	ret = nilfs_btree_get_block(btree, ptr, &bh);
2341 	if (ret < 0) {
2342 		WARN_ON(ret == -ENOENT);
2343 		goto out;
2344 	}
2345 
2346 	if (!buffer_dirty(bh))
2347 		mark_buffer_dirty(bh);
2348 	brelse(bh);
2349 	if (!nilfs_bmap_dirty(btree))
2350 		nilfs_bmap_set_dirty(btree);
2351 
2352  out:
2353 	nilfs_btree_free_path(path);
2354 	return ret;
2355 }
2356 
2357 static const struct nilfs_bmap_operations nilfs_btree_ops = {
2358 	.bop_lookup		=	nilfs_btree_lookup,
2359 	.bop_lookup_contig	=	nilfs_btree_lookup_contig,
2360 	.bop_insert		=	nilfs_btree_insert,
2361 	.bop_delete		=	nilfs_btree_delete,
2362 	.bop_clear		=	NULL,
2363 
2364 	.bop_propagate		=	nilfs_btree_propagate,
2365 
2366 	.bop_lookup_dirty_buffers =	nilfs_btree_lookup_dirty_buffers,
2367 
2368 	.bop_assign		=	nilfs_btree_assign,
2369 	.bop_mark		=	nilfs_btree_mark,
2370 
2371 	.bop_seek_key		=	nilfs_btree_seek_key,
2372 	.bop_last_key		=	nilfs_btree_last_key,
2373 
2374 	.bop_check_insert	=	NULL,
2375 	.bop_check_delete	=	nilfs_btree_check_delete,
2376 	.bop_gather_data	=	nilfs_btree_gather_data,
2377 };
2378 
2379 static const struct nilfs_bmap_operations nilfs_btree_ops_gc = {
2380 	.bop_lookup		=	NULL,
2381 	.bop_lookup_contig	=	NULL,
2382 	.bop_insert		=	NULL,
2383 	.bop_delete		=	NULL,
2384 	.bop_clear		=	NULL,
2385 
2386 	.bop_propagate		=	nilfs_btree_propagate_gc,
2387 
2388 	.bop_lookup_dirty_buffers =	nilfs_btree_lookup_dirty_buffers,
2389 
2390 	.bop_assign		=	nilfs_btree_assign_gc,
2391 	.bop_mark		=	NULL,
2392 
2393 	.bop_seek_key		=	NULL,
2394 	.bop_last_key		=	NULL,
2395 
2396 	.bop_check_insert	=	NULL,
2397 	.bop_check_delete	=	NULL,
2398 	.bop_gather_data	=	NULL,
2399 };
2400 
2401 static void __nilfs_btree_init(struct nilfs_bmap *bmap)
2402 {
2403 	bmap->b_ops = &nilfs_btree_ops;
2404 	bmap->b_nchildren_per_block =
2405 		NILFS_BTREE_NODE_NCHILDREN_MAX(nilfs_btree_node_size(bmap));
2406 }
2407 
2408 int nilfs_btree_init(struct nilfs_bmap *bmap)
2409 {
2410 	int ret = 0;
2411 
2412 	__nilfs_btree_init(bmap);
2413 
2414 	if (nilfs_btree_root_broken(nilfs_btree_get_root(bmap), bmap->b_inode))
2415 		ret = -EIO;
2416 	else
2417 		ret = nilfs_attach_btree_node_cache(
2418 			&NILFS_BMAP_I(bmap)->vfs_inode);
2419 
2420 	return ret;
2421 }
2422 
2423 void nilfs_btree_init_gc(struct nilfs_bmap *bmap)
2424 {
2425 	bmap->b_ops = &nilfs_btree_ops_gc;
2426 	bmap->b_nchildren_per_block =
2427 		NILFS_BTREE_NODE_NCHILDREN_MAX(nilfs_btree_node_size(bmap));
2428 }
2429