xref: /openbmc/linux/fs/btrfs/file-item.c (revision e7db9e5c)
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * Copyright (C) 2007 Oracle.  All rights reserved.
4  */
5 
6 #include <linux/bio.h>
7 #include <linux/slab.h>
8 #include <linux/pagemap.h>
9 #include <linux/highmem.h>
10 #include <linux/sched/mm.h>
11 #include <crypto/hash.h>
12 #include "messages.h"
13 #include "misc.h"
14 #include "ctree.h"
15 #include "disk-io.h"
16 #include "transaction.h"
17 #include "bio.h"
18 #include "print-tree.h"
19 #include "compression.h"
20 #include "fs.h"
21 #include "accessors.h"
22 #include "file-item.h"
23 #include "super.h"
24 
25 #define __MAX_CSUM_ITEMS(r, size) ((unsigned long)(((BTRFS_LEAF_DATA_SIZE(r) - \
26 				   sizeof(struct btrfs_item) * 2) / \
27 				  size) - 1))
28 
29 #define MAX_CSUM_ITEMS(r, size) (min_t(u32, __MAX_CSUM_ITEMS(r, size), \
30 				       PAGE_SIZE))
31 
32 /*
33  * Set inode's size according to filesystem options.
34  *
35  * @inode:      inode we want to update the disk_i_size for
36  * @new_i_size: i_size we want to set to, 0 if we use i_size
37  *
38  * With NO_HOLES set this simply sets the disk_is_size to whatever i_size_read()
39  * returns as it is perfectly fine with a file that has holes without hole file
40  * extent items.
41  *
42  * However without NO_HOLES we need to only return the area that is contiguous
43  * from the 0 offset of the file.  Otherwise we could end up adjust i_size up
44  * to an extent that has a gap in between.
45  *
46  * Finally new_i_size should only be set in the case of truncate where we're not
47  * ready to use i_size_read() as the limiter yet.
48  */
49 void btrfs_inode_safe_disk_i_size_write(struct btrfs_inode *inode, u64 new_i_size)
50 {
51 	struct btrfs_fs_info *fs_info = inode->root->fs_info;
52 	u64 start, end, i_size;
53 	int ret;
54 
55 	spin_lock(&inode->lock);
56 	i_size = new_i_size ?: i_size_read(&inode->vfs_inode);
57 	if (btrfs_fs_incompat(fs_info, NO_HOLES)) {
58 		inode->disk_i_size = i_size;
59 		goto out_unlock;
60 	}
61 
62 	ret = find_contiguous_extent_bit(&inode->file_extent_tree, 0, &start,
63 					 &end, EXTENT_DIRTY);
64 	if (!ret && start == 0)
65 		i_size = min(i_size, end + 1);
66 	else
67 		i_size = 0;
68 	inode->disk_i_size = i_size;
69 out_unlock:
70 	spin_unlock(&inode->lock);
71 }
72 
73 /*
74  * Mark range within a file as having a new extent inserted.
75  *
76  * @inode: inode being modified
77  * @start: start file offset of the file extent we've inserted
78  * @len:   logical length of the file extent item
79  *
80  * Call when we are inserting a new file extent where there was none before.
81  * Does not need to call this in the case where we're replacing an existing file
82  * extent, however if not sure it's fine to call this multiple times.
83  *
84  * The start and len must match the file extent item, so thus must be sectorsize
85  * aligned.
86  */
87 int btrfs_inode_set_file_extent_range(struct btrfs_inode *inode, u64 start,
88 				      u64 len)
89 {
90 	if (len == 0)
91 		return 0;
92 
93 	ASSERT(IS_ALIGNED(start + len, inode->root->fs_info->sectorsize));
94 
95 	if (btrfs_fs_incompat(inode->root->fs_info, NO_HOLES))
96 		return 0;
97 	return set_extent_bits(&inode->file_extent_tree, start, start + len - 1,
98 			       EXTENT_DIRTY);
99 }
100 
101 /*
102  * Mark an inode range as not having a backing extent.
103  *
104  * @inode: inode being modified
105  * @start: start file offset of the file extent we've inserted
106  * @len:   logical length of the file extent item
107  *
108  * Called when we drop a file extent, for example when we truncate.  Doesn't
109  * need to be called for cases where we're replacing a file extent, like when
110  * we've COWed a file extent.
111  *
112  * The start and len must match the file extent item, so thus must be sectorsize
113  * aligned.
114  */
115 int btrfs_inode_clear_file_extent_range(struct btrfs_inode *inode, u64 start,
116 					u64 len)
117 {
118 	if (len == 0)
119 		return 0;
120 
121 	ASSERT(IS_ALIGNED(start + len, inode->root->fs_info->sectorsize) ||
122 	       len == (u64)-1);
123 
124 	if (btrfs_fs_incompat(inode->root->fs_info, NO_HOLES))
125 		return 0;
126 	return clear_extent_bit(&inode->file_extent_tree, start,
127 				start + len - 1, EXTENT_DIRTY, NULL);
128 }
129 
130 static size_t bytes_to_csum_size(const struct btrfs_fs_info *fs_info, u32 bytes)
131 {
132 	ASSERT(IS_ALIGNED(bytes, fs_info->sectorsize));
133 
134 	return (bytes >> fs_info->sectorsize_bits) * fs_info->csum_size;
135 }
136 
137 static size_t csum_size_to_bytes(const struct btrfs_fs_info *fs_info, u32 csum_size)
138 {
139 	ASSERT(IS_ALIGNED(csum_size, fs_info->csum_size));
140 
141 	return (csum_size / fs_info->csum_size) << fs_info->sectorsize_bits;
142 }
143 
144 static inline u32 max_ordered_sum_bytes(const struct btrfs_fs_info *fs_info)
145 {
146 	u32 max_csum_size = round_down(PAGE_SIZE - sizeof(struct btrfs_ordered_sum),
147 				       fs_info->csum_size);
148 
149 	return csum_size_to_bytes(fs_info, max_csum_size);
150 }
151 
152 /*
153  * Calculate the total size needed to allocate for an ordered sum structure
154  * spanning @bytes in the file.
155  */
156 static int btrfs_ordered_sum_size(struct btrfs_fs_info *fs_info, unsigned long bytes)
157 {
158 	return sizeof(struct btrfs_ordered_sum) + bytes_to_csum_size(fs_info, bytes);
159 }
160 
161 int btrfs_insert_hole_extent(struct btrfs_trans_handle *trans,
162 			     struct btrfs_root *root,
163 			     u64 objectid, u64 pos, u64 num_bytes)
164 {
165 	int ret = 0;
166 	struct btrfs_file_extent_item *item;
167 	struct btrfs_key file_key;
168 	struct btrfs_path *path;
169 	struct extent_buffer *leaf;
170 
171 	path = btrfs_alloc_path();
172 	if (!path)
173 		return -ENOMEM;
174 	file_key.objectid = objectid;
175 	file_key.offset = pos;
176 	file_key.type = BTRFS_EXTENT_DATA_KEY;
177 
178 	ret = btrfs_insert_empty_item(trans, root, path, &file_key,
179 				      sizeof(*item));
180 	if (ret < 0)
181 		goto out;
182 	BUG_ON(ret); /* Can't happen */
183 	leaf = path->nodes[0];
184 	item = btrfs_item_ptr(leaf, path->slots[0],
185 			      struct btrfs_file_extent_item);
186 	btrfs_set_file_extent_disk_bytenr(leaf, item, 0);
187 	btrfs_set_file_extent_disk_num_bytes(leaf, item, 0);
188 	btrfs_set_file_extent_offset(leaf, item, 0);
189 	btrfs_set_file_extent_num_bytes(leaf, item, num_bytes);
190 	btrfs_set_file_extent_ram_bytes(leaf, item, num_bytes);
191 	btrfs_set_file_extent_generation(leaf, item, trans->transid);
192 	btrfs_set_file_extent_type(leaf, item, BTRFS_FILE_EXTENT_REG);
193 	btrfs_set_file_extent_compression(leaf, item, 0);
194 	btrfs_set_file_extent_encryption(leaf, item, 0);
195 	btrfs_set_file_extent_other_encoding(leaf, item, 0);
196 
197 	btrfs_mark_buffer_dirty(leaf);
198 out:
199 	btrfs_free_path(path);
200 	return ret;
201 }
202 
203 static struct btrfs_csum_item *
204 btrfs_lookup_csum(struct btrfs_trans_handle *trans,
205 		  struct btrfs_root *root,
206 		  struct btrfs_path *path,
207 		  u64 bytenr, int cow)
208 {
209 	struct btrfs_fs_info *fs_info = root->fs_info;
210 	int ret;
211 	struct btrfs_key file_key;
212 	struct btrfs_key found_key;
213 	struct btrfs_csum_item *item;
214 	struct extent_buffer *leaf;
215 	u64 csum_offset = 0;
216 	const u32 csum_size = fs_info->csum_size;
217 	int csums_in_item;
218 
219 	file_key.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
220 	file_key.offset = bytenr;
221 	file_key.type = BTRFS_EXTENT_CSUM_KEY;
222 	ret = btrfs_search_slot(trans, root, &file_key, path, 0, cow);
223 	if (ret < 0)
224 		goto fail;
225 	leaf = path->nodes[0];
226 	if (ret > 0) {
227 		ret = 1;
228 		if (path->slots[0] == 0)
229 			goto fail;
230 		path->slots[0]--;
231 		btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
232 		if (found_key.type != BTRFS_EXTENT_CSUM_KEY)
233 			goto fail;
234 
235 		csum_offset = (bytenr - found_key.offset) >>
236 				fs_info->sectorsize_bits;
237 		csums_in_item = btrfs_item_size(leaf, path->slots[0]);
238 		csums_in_item /= csum_size;
239 
240 		if (csum_offset == csums_in_item) {
241 			ret = -EFBIG;
242 			goto fail;
243 		} else if (csum_offset > csums_in_item) {
244 			goto fail;
245 		}
246 	}
247 	item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_csum_item);
248 	item = (struct btrfs_csum_item *)((unsigned char *)item +
249 					  csum_offset * csum_size);
250 	return item;
251 fail:
252 	if (ret > 0)
253 		ret = -ENOENT;
254 	return ERR_PTR(ret);
255 }
256 
257 int btrfs_lookup_file_extent(struct btrfs_trans_handle *trans,
258 			     struct btrfs_root *root,
259 			     struct btrfs_path *path, u64 objectid,
260 			     u64 offset, int mod)
261 {
262 	struct btrfs_key file_key;
263 	int ins_len = mod < 0 ? -1 : 0;
264 	int cow = mod != 0;
265 
266 	file_key.objectid = objectid;
267 	file_key.offset = offset;
268 	file_key.type = BTRFS_EXTENT_DATA_KEY;
269 
270 	return btrfs_search_slot(trans, root, &file_key, path, ins_len, cow);
271 }
272 
273 /*
274  * Find checksums for logical bytenr range [disk_bytenr, disk_bytenr + len) and
275  * store the result to @dst.
276  *
277  * Return >0 for the number of sectors we found.
278  * Return 0 for the range [disk_bytenr, disk_bytenr + sectorsize) has no csum
279  * for it. Caller may want to try next sector until one range is hit.
280  * Return <0 for fatal error.
281  */
282 static int search_csum_tree(struct btrfs_fs_info *fs_info,
283 			    struct btrfs_path *path, u64 disk_bytenr,
284 			    u64 len, u8 *dst)
285 {
286 	struct btrfs_root *csum_root;
287 	struct btrfs_csum_item *item = NULL;
288 	struct btrfs_key key;
289 	const u32 sectorsize = fs_info->sectorsize;
290 	const u32 csum_size = fs_info->csum_size;
291 	u32 itemsize;
292 	int ret;
293 	u64 csum_start;
294 	u64 csum_len;
295 
296 	ASSERT(IS_ALIGNED(disk_bytenr, sectorsize) &&
297 	       IS_ALIGNED(len, sectorsize));
298 
299 	/* Check if the current csum item covers disk_bytenr */
300 	if (path->nodes[0]) {
301 		item = btrfs_item_ptr(path->nodes[0], path->slots[0],
302 				      struct btrfs_csum_item);
303 		btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
304 		itemsize = btrfs_item_size(path->nodes[0], path->slots[0]);
305 
306 		csum_start = key.offset;
307 		csum_len = (itemsize / csum_size) * sectorsize;
308 
309 		if (in_range(disk_bytenr, csum_start, csum_len))
310 			goto found;
311 	}
312 
313 	/* Current item doesn't contain the desired range, search again */
314 	btrfs_release_path(path);
315 	csum_root = btrfs_csum_root(fs_info, disk_bytenr);
316 	item = btrfs_lookup_csum(NULL, csum_root, path, disk_bytenr, 0);
317 	if (IS_ERR(item)) {
318 		ret = PTR_ERR(item);
319 		goto out;
320 	}
321 	btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
322 	itemsize = btrfs_item_size(path->nodes[0], path->slots[0]);
323 
324 	csum_start = key.offset;
325 	csum_len = (itemsize / csum_size) * sectorsize;
326 	ASSERT(in_range(disk_bytenr, csum_start, csum_len));
327 
328 found:
329 	ret = (min(csum_start + csum_len, disk_bytenr + len) -
330 		   disk_bytenr) >> fs_info->sectorsize_bits;
331 	read_extent_buffer(path->nodes[0], dst, (unsigned long)item,
332 			ret * csum_size);
333 out:
334 	if (ret == -ENOENT || ret == -EFBIG)
335 		ret = 0;
336 	return ret;
337 }
338 
339 /*
340  * Lookup the checksum for the read bio in csum tree.
341  *
342  * Return: BLK_STS_RESOURCE if allocating memory fails, BLK_STS_OK otherwise.
343  */
344 blk_status_t btrfs_lookup_bio_sums(struct btrfs_bio *bbio)
345 {
346 	struct btrfs_inode *inode = bbio->inode;
347 	struct btrfs_fs_info *fs_info = inode->root->fs_info;
348 	struct bio *bio = &bbio->bio;
349 	struct btrfs_path *path;
350 	const u32 sectorsize = fs_info->sectorsize;
351 	const u32 csum_size = fs_info->csum_size;
352 	u32 orig_len = bio->bi_iter.bi_size;
353 	u64 orig_disk_bytenr = bio->bi_iter.bi_sector << SECTOR_SHIFT;
354 	const unsigned int nblocks = orig_len >> fs_info->sectorsize_bits;
355 	blk_status_t ret = BLK_STS_OK;
356 	u32 bio_offset = 0;
357 
358 	if ((inode->flags & BTRFS_INODE_NODATASUM) ||
359 	    test_bit(BTRFS_FS_STATE_NO_CSUMS, &fs_info->fs_state))
360 		return BLK_STS_OK;
361 
362 	/*
363 	 * This function is only called for read bio.
364 	 *
365 	 * This means two things:
366 	 * - All our csums should only be in csum tree
367 	 *   No ordered extents csums, as ordered extents are only for write
368 	 *   path.
369 	 * - No need to bother any other info from bvec
370 	 *   Since we're looking up csums, the only important info is the
371 	 *   disk_bytenr and the length, which can be extracted from bi_iter
372 	 *   directly.
373 	 */
374 	ASSERT(bio_op(bio) == REQ_OP_READ);
375 	path = btrfs_alloc_path();
376 	if (!path)
377 		return BLK_STS_RESOURCE;
378 
379 	if (nblocks * csum_size > BTRFS_BIO_INLINE_CSUM_SIZE) {
380 		bbio->csum = kmalloc_array(nblocks, csum_size, GFP_NOFS);
381 		if (!bbio->csum) {
382 			btrfs_free_path(path);
383 			return BLK_STS_RESOURCE;
384 		}
385 	} else {
386 		bbio->csum = bbio->csum_inline;
387 	}
388 
389 	/*
390 	 * If requested number of sectors is larger than one leaf can contain,
391 	 * kick the readahead for csum tree.
392 	 */
393 	if (nblocks > fs_info->csums_per_leaf)
394 		path->reada = READA_FORWARD;
395 
396 	/*
397 	 * the free space stuff is only read when it hasn't been
398 	 * updated in the current transaction.  So, we can safely
399 	 * read from the commit root and sidestep a nasty deadlock
400 	 * between reading the free space cache and updating the csum tree.
401 	 */
402 	if (btrfs_is_free_space_inode(inode)) {
403 		path->search_commit_root = 1;
404 		path->skip_locking = 1;
405 	}
406 
407 	while (bio_offset < orig_len) {
408 		int count;
409 		u64 cur_disk_bytenr = orig_disk_bytenr + bio_offset;
410 		u8 *csum_dst = bbio->csum +
411 			(bio_offset >> fs_info->sectorsize_bits) * csum_size;
412 
413 		count = search_csum_tree(fs_info, path, cur_disk_bytenr,
414 					 orig_len - bio_offset, csum_dst);
415 		if (count < 0) {
416 			ret = errno_to_blk_status(count);
417 			if (bbio->csum != bbio->csum_inline)
418 				kfree(bbio->csum);
419 			bbio->csum = NULL;
420 			break;
421 		}
422 
423 		/*
424 		 * We didn't find a csum for this range.  We need to make sure
425 		 * we complain loudly about this, because we are not NODATASUM.
426 		 *
427 		 * However for the DATA_RELOC inode we could potentially be
428 		 * relocating data extents for a NODATASUM inode, so the inode
429 		 * itself won't be marked with NODATASUM, but the extent we're
430 		 * copying is in fact NODATASUM.  If we don't find a csum we
431 		 * assume this is the case.
432 		 */
433 		if (count == 0) {
434 			memset(csum_dst, 0, csum_size);
435 			count = 1;
436 
437 			if (inode->root->root_key.objectid ==
438 			    BTRFS_DATA_RELOC_TREE_OBJECTID) {
439 				u64 file_offset = bbio->file_offset + bio_offset;
440 
441 				set_extent_bits(&inode->io_tree, file_offset,
442 						file_offset + sectorsize - 1,
443 						EXTENT_NODATASUM);
444 			} else {
445 				btrfs_warn_rl(fs_info,
446 			"csum hole found for disk bytenr range [%llu, %llu)",
447 				cur_disk_bytenr, cur_disk_bytenr + sectorsize);
448 			}
449 		}
450 		bio_offset += count * sectorsize;
451 	}
452 
453 	btrfs_free_path(path);
454 	return ret;
455 }
456 
457 int btrfs_lookup_csums_list(struct btrfs_root *root, u64 start, u64 end,
458 			    struct list_head *list, int search_commit,
459 			    bool nowait)
460 {
461 	struct btrfs_fs_info *fs_info = root->fs_info;
462 	struct btrfs_key key;
463 	struct btrfs_path *path;
464 	struct extent_buffer *leaf;
465 	struct btrfs_ordered_sum *sums;
466 	struct btrfs_csum_item *item;
467 	LIST_HEAD(tmplist);
468 	int ret;
469 
470 	ASSERT(IS_ALIGNED(start, fs_info->sectorsize) &&
471 	       IS_ALIGNED(end + 1, fs_info->sectorsize));
472 
473 	path = btrfs_alloc_path();
474 	if (!path)
475 		return -ENOMEM;
476 
477 	path->nowait = nowait;
478 	if (search_commit) {
479 		path->skip_locking = 1;
480 		path->reada = READA_FORWARD;
481 		path->search_commit_root = 1;
482 	}
483 
484 	key.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
485 	key.offset = start;
486 	key.type = BTRFS_EXTENT_CSUM_KEY;
487 
488 	ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
489 	if (ret < 0)
490 		goto fail;
491 	if (ret > 0 && path->slots[0] > 0) {
492 		leaf = path->nodes[0];
493 		btrfs_item_key_to_cpu(leaf, &key, path->slots[0] - 1);
494 
495 		/*
496 		 * There are two cases we can hit here for the previous csum
497 		 * item:
498 		 *
499 		 *		|<- search range ->|
500 		 *	|<- csum item ->|
501 		 *
502 		 * Or
503 		 *				|<- search range ->|
504 		 *	|<- csum item ->|
505 		 *
506 		 * Check if the previous csum item covers the leading part of
507 		 * the search range.  If so we have to start from previous csum
508 		 * item.
509 		 */
510 		if (key.objectid == BTRFS_EXTENT_CSUM_OBJECTID &&
511 		    key.type == BTRFS_EXTENT_CSUM_KEY) {
512 			if (bytes_to_csum_size(fs_info, start - key.offset) <
513 			    btrfs_item_size(leaf, path->slots[0] - 1))
514 				path->slots[0]--;
515 		}
516 	}
517 
518 	while (start <= end) {
519 		u64 csum_end;
520 
521 		leaf = path->nodes[0];
522 		if (path->slots[0] >= btrfs_header_nritems(leaf)) {
523 			ret = btrfs_next_leaf(root, path);
524 			if (ret < 0)
525 				goto fail;
526 			if (ret > 0)
527 				break;
528 			leaf = path->nodes[0];
529 		}
530 
531 		btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
532 		if (key.objectid != BTRFS_EXTENT_CSUM_OBJECTID ||
533 		    key.type != BTRFS_EXTENT_CSUM_KEY ||
534 		    key.offset > end)
535 			break;
536 
537 		if (key.offset > start)
538 			start = key.offset;
539 
540 		csum_end = key.offset + csum_size_to_bytes(fs_info,
541 					btrfs_item_size(leaf, path->slots[0]));
542 		if (csum_end <= start) {
543 			path->slots[0]++;
544 			continue;
545 		}
546 
547 		csum_end = min(csum_end, end + 1);
548 		item = btrfs_item_ptr(path->nodes[0], path->slots[0],
549 				      struct btrfs_csum_item);
550 		while (start < csum_end) {
551 			unsigned long offset;
552 			size_t size;
553 
554 			size = min_t(size_t, csum_end - start,
555 				     max_ordered_sum_bytes(fs_info));
556 			sums = kzalloc(btrfs_ordered_sum_size(fs_info, size),
557 				       GFP_NOFS);
558 			if (!sums) {
559 				ret = -ENOMEM;
560 				goto fail;
561 			}
562 
563 			sums->bytenr = start;
564 			sums->len = (int)size;
565 
566 			offset = bytes_to_csum_size(fs_info, start - key.offset);
567 
568 			read_extent_buffer(path->nodes[0],
569 					   sums->sums,
570 					   ((unsigned long)item) + offset,
571 					   bytes_to_csum_size(fs_info, size));
572 
573 			start += size;
574 			list_add_tail(&sums->list, &tmplist);
575 		}
576 		path->slots[0]++;
577 	}
578 	ret = 0;
579 fail:
580 	while (ret < 0 && !list_empty(&tmplist)) {
581 		sums = list_entry(tmplist.next, struct btrfs_ordered_sum, list);
582 		list_del(&sums->list);
583 		kfree(sums);
584 	}
585 	list_splice_tail(&tmplist, list);
586 
587 	btrfs_free_path(path);
588 	return ret;
589 }
590 
591 /*
592  * Do the same work as btrfs_lookup_csums_list(), the difference is in how
593  * we return the result.
594  *
595  * This version will set the corresponding bits in @csum_bitmap to represent
596  * that there is a csum found.
597  * Each bit represents a sector. Thus caller should ensure @csum_buf passed
598  * in is large enough to contain all csums.
599  */
600 int btrfs_lookup_csums_bitmap(struct btrfs_root *root, u64 start, u64 end,
601 			      u8 *csum_buf, unsigned long *csum_bitmap,
602 			      bool search_commit)
603 {
604 	struct btrfs_fs_info *fs_info = root->fs_info;
605 	struct btrfs_key key;
606 	struct btrfs_path *path;
607 	struct extent_buffer *leaf;
608 	struct btrfs_csum_item *item;
609 	const u64 orig_start = start;
610 	int ret;
611 
612 	ASSERT(IS_ALIGNED(start, fs_info->sectorsize) &&
613 	       IS_ALIGNED(end + 1, fs_info->sectorsize));
614 
615 	path = btrfs_alloc_path();
616 	if (!path)
617 		return -ENOMEM;
618 
619 	if (search_commit) {
620 		path->skip_locking = 1;
621 		path->reada = READA_FORWARD;
622 		path->search_commit_root = 1;
623 	}
624 
625 	key.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
626 	key.type = BTRFS_EXTENT_CSUM_KEY;
627 	key.offset = start;
628 
629 	ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
630 	if (ret < 0)
631 		goto fail;
632 	if (ret > 0 && path->slots[0] > 0) {
633 		leaf = path->nodes[0];
634 		btrfs_item_key_to_cpu(leaf, &key, path->slots[0] - 1);
635 
636 		/*
637 		 * There are two cases we can hit here for the previous csum
638 		 * item:
639 		 *
640 		 *		|<- search range ->|
641 		 *	|<- csum item ->|
642 		 *
643 		 * Or
644 		 *				|<- search range ->|
645 		 *	|<- csum item ->|
646 		 *
647 		 * Check if the previous csum item covers the leading part of
648 		 * the search range.  If so we have to start from previous csum
649 		 * item.
650 		 */
651 		if (key.objectid == BTRFS_EXTENT_CSUM_OBJECTID &&
652 		    key.type == BTRFS_EXTENT_CSUM_KEY) {
653 			if (bytes_to_csum_size(fs_info, start - key.offset) <
654 			    btrfs_item_size(leaf, path->slots[0] - 1))
655 				path->slots[0]--;
656 		}
657 	}
658 
659 	while (start <= end) {
660 		u64 csum_end;
661 
662 		leaf = path->nodes[0];
663 		if (path->slots[0] >= btrfs_header_nritems(leaf)) {
664 			ret = btrfs_next_leaf(root, path);
665 			if (ret < 0)
666 				goto fail;
667 			if (ret > 0)
668 				break;
669 			leaf = path->nodes[0];
670 		}
671 
672 		btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
673 		if (key.objectid != BTRFS_EXTENT_CSUM_OBJECTID ||
674 		    key.type != BTRFS_EXTENT_CSUM_KEY ||
675 		    key.offset > end)
676 			break;
677 
678 		if (key.offset > start)
679 			start = key.offset;
680 
681 		csum_end = key.offset + csum_size_to_bytes(fs_info,
682 					btrfs_item_size(leaf, path->slots[0]));
683 		if (csum_end <= start) {
684 			path->slots[0]++;
685 			continue;
686 		}
687 
688 		csum_end = min(csum_end, end + 1);
689 		item = btrfs_item_ptr(path->nodes[0], path->slots[0],
690 				      struct btrfs_csum_item);
691 		while (start < csum_end) {
692 			unsigned long offset;
693 			size_t size;
694 			u8 *csum_dest = csum_buf + bytes_to_csum_size(fs_info,
695 						start - orig_start);
696 
697 			size = min_t(size_t, csum_end - start, end + 1 - start);
698 
699 			offset = bytes_to_csum_size(fs_info, start - key.offset);
700 
701 			read_extent_buffer(path->nodes[0], csum_dest,
702 					   ((unsigned long)item) + offset,
703 					   bytes_to_csum_size(fs_info, size));
704 
705 			bitmap_set(csum_bitmap,
706 				(start - orig_start) >> fs_info->sectorsize_bits,
707 				size >> fs_info->sectorsize_bits);
708 
709 			start += size;
710 		}
711 		path->slots[0]++;
712 	}
713 	ret = 0;
714 fail:
715 	btrfs_free_path(path);
716 	return ret;
717 }
718 
719 /*
720  * Calculate checksums of the data contained inside a bio.
721  */
722 blk_status_t btrfs_csum_one_bio(struct btrfs_bio *bbio)
723 {
724 	struct btrfs_inode *inode = bbio->inode;
725 	struct btrfs_fs_info *fs_info = inode->root->fs_info;
726 	SHASH_DESC_ON_STACK(shash, fs_info->csum_shash);
727 	struct bio *bio = &bbio->bio;
728 	u64 offset = bbio->file_offset;
729 	struct btrfs_ordered_sum *sums;
730 	struct btrfs_ordered_extent *ordered = NULL;
731 	char *data;
732 	struct bvec_iter iter;
733 	struct bio_vec bvec;
734 	int index;
735 	unsigned int blockcount;
736 	unsigned long total_bytes = 0;
737 	unsigned long this_sum_bytes = 0;
738 	int i;
739 	unsigned nofs_flag;
740 
741 	nofs_flag = memalloc_nofs_save();
742 	sums = kvzalloc(btrfs_ordered_sum_size(fs_info, bio->bi_iter.bi_size),
743 		       GFP_KERNEL);
744 	memalloc_nofs_restore(nofs_flag);
745 
746 	if (!sums)
747 		return BLK_STS_RESOURCE;
748 
749 	sums->len = bio->bi_iter.bi_size;
750 	INIT_LIST_HEAD(&sums->list);
751 
752 	sums->bytenr = bio->bi_iter.bi_sector << 9;
753 	index = 0;
754 
755 	shash->tfm = fs_info->csum_shash;
756 
757 	bio_for_each_segment(bvec, bio, iter) {
758 		if (!ordered) {
759 			ordered = btrfs_lookup_ordered_extent(inode, offset);
760 			/*
761 			 * The bio range is not covered by any ordered extent,
762 			 * must be a code logic error.
763 			 */
764 			if (unlikely(!ordered)) {
765 				WARN(1, KERN_WARNING
766 			"no ordered extent for root %llu ino %llu offset %llu\n",
767 				     inode->root->root_key.objectid,
768 				     btrfs_ino(inode), offset);
769 				kvfree(sums);
770 				return BLK_STS_IOERR;
771 			}
772 		}
773 
774 		blockcount = BTRFS_BYTES_TO_BLKS(fs_info,
775 						 bvec.bv_len + fs_info->sectorsize
776 						 - 1);
777 
778 		for (i = 0; i < blockcount; i++) {
779 			if (!(bio->bi_opf & REQ_BTRFS_ONE_ORDERED) &&
780 			    !in_range(offset, ordered->file_offset,
781 				      ordered->num_bytes)) {
782 				unsigned long bytes_left;
783 
784 				sums->len = this_sum_bytes;
785 				this_sum_bytes = 0;
786 				btrfs_add_ordered_sum(ordered, sums);
787 				btrfs_put_ordered_extent(ordered);
788 
789 				bytes_left = bio->bi_iter.bi_size - total_bytes;
790 
791 				nofs_flag = memalloc_nofs_save();
792 				sums = kvzalloc(btrfs_ordered_sum_size(fs_info,
793 						      bytes_left), GFP_KERNEL);
794 				memalloc_nofs_restore(nofs_flag);
795 				BUG_ON(!sums); /* -ENOMEM */
796 				sums->len = bytes_left;
797 				ordered = btrfs_lookup_ordered_extent(inode,
798 								offset);
799 				ASSERT(ordered); /* Logic error */
800 				sums->bytenr = (bio->bi_iter.bi_sector << 9)
801 					+ total_bytes;
802 				index = 0;
803 			}
804 
805 			data = bvec_kmap_local(&bvec);
806 			crypto_shash_digest(shash,
807 					    data + (i * fs_info->sectorsize),
808 					    fs_info->sectorsize,
809 					    sums->sums + index);
810 			kunmap_local(data);
811 			index += fs_info->csum_size;
812 			offset += fs_info->sectorsize;
813 			this_sum_bytes += fs_info->sectorsize;
814 			total_bytes += fs_info->sectorsize;
815 		}
816 
817 	}
818 	this_sum_bytes = 0;
819 	btrfs_add_ordered_sum(ordered, sums);
820 	btrfs_put_ordered_extent(ordered);
821 	return 0;
822 }
823 
824 /*
825  * Remove one checksum overlapping a range.
826  *
827  * This expects the key to describe the csum pointed to by the path, and it
828  * expects the csum to overlap the range [bytenr, len]
829  *
830  * The csum should not be entirely contained in the range and the range should
831  * not be entirely contained in the csum.
832  *
833  * This calls btrfs_truncate_item with the correct args based on the overlap,
834  * and fixes up the key as required.
835  */
836 static noinline void truncate_one_csum(struct btrfs_fs_info *fs_info,
837 				       struct btrfs_path *path,
838 				       struct btrfs_key *key,
839 				       u64 bytenr, u64 len)
840 {
841 	struct extent_buffer *leaf;
842 	const u32 csum_size = fs_info->csum_size;
843 	u64 csum_end;
844 	u64 end_byte = bytenr + len;
845 	u32 blocksize_bits = fs_info->sectorsize_bits;
846 
847 	leaf = path->nodes[0];
848 	csum_end = btrfs_item_size(leaf, path->slots[0]) / csum_size;
849 	csum_end <<= blocksize_bits;
850 	csum_end += key->offset;
851 
852 	if (key->offset < bytenr && csum_end <= end_byte) {
853 		/*
854 		 *         [ bytenr - len ]
855 		 *         [   ]
856 		 *   [csum     ]
857 		 *   A simple truncate off the end of the item
858 		 */
859 		u32 new_size = (bytenr - key->offset) >> blocksize_bits;
860 		new_size *= csum_size;
861 		btrfs_truncate_item(path, new_size, 1);
862 	} else if (key->offset >= bytenr && csum_end > end_byte &&
863 		   end_byte > key->offset) {
864 		/*
865 		 *         [ bytenr - len ]
866 		 *                 [ ]
867 		 *                 [csum     ]
868 		 * we need to truncate from the beginning of the csum
869 		 */
870 		u32 new_size = (csum_end - end_byte) >> blocksize_bits;
871 		new_size *= csum_size;
872 
873 		btrfs_truncate_item(path, new_size, 0);
874 
875 		key->offset = end_byte;
876 		btrfs_set_item_key_safe(fs_info, path, key);
877 	} else {
878 		BUG();
879 	}
880 }
881 
882 /*
883  * Delete the csum items from the csum tree for a given range of bytes.
884  */
885 int btrfs_del_csums(struct btrfs_trans_handle *trans,
886 		    struct btrfs_root *root, u64 bytenr, u64 len)
887 {
888 	struct btrfs_fs_info *fs_info = trans->fs_info;
889 	struct btrfs_path *path;
890 	struct btrfs_key key;
891 	u64 end_byte = bytenr + len;
892 	u64 csum_end;
893 	struct extent_buffer *leaf;
894 	int ret = 0;
895 	const u32 csum_size = fs_info->csum_size;
896 	u32 blocksize_bits = fs_info->sectorsize_bits;
897 
898 	ASSERT(root->root_key.objectid == BTRFS_CSUM_TREE_OBJECTID ||
899 	       root->root_key.objectid == BTRFS_TREE_LOG_OBJECTID);
900 
901 	path = btrfs_alloc_path();
902 	if (!path)
903 		return -ENOMEM;
904 
905 	while (1) {
906 		key.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
907 		key.offset = end_byte - 1;
908 		key.type = BTRFS_EXTENT_CSUM_KEY;
909 
910 		ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
911 		if (ret > 0) {
912 			ret = 0;
913 			if (path->slots[0] == 0)
914 				break;
915 			path->slots[0]--;
916 		} else if (ret < 0) {
917 			break;
918 		}
919 
920 		leaf = path->nodes[0];
921 		btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
922 
923 		if (key.objectid != BTRFS_EXTENT_CSUM_OBJECTID ||
924 		    key.type != BTRFS_EXTENT_CSUM_KEY) {
925 			break;
926 		}
927 
928 		if (key.offset >= end_byte)
929 			break;
930 
931 		csum_end = btrfs_item_size(leaf, path->slots[0]) / csum_size;
932 		csum_end <<= blocksize_bits;
933 		csum_end += key.offset;
934 
935 		/* this csum ends before we start, we're done */
936 		if (csum_end <= bytenr)
937 			break;
938 
939 		/* delete the entire item, it is inside our range */
940 		if (key.offset >= bytenr && csum_end <= end_byte) {
941 			int del_nr = 1;
942 
943 			/*
944 			 * Check how many csum items preceding this one in this
945 			 * leaf correspond to our range and then delete them all
946 			 * at once.
947 			 */
948 			if (key.offset > bytenr && path->slots[0] > 0) {
949 				int slot = path->slots[0] - 1;
950 
951 				while (slot >= 0) {
952 					struct btrfs_key pk;
953 
954 					btrfs_item_key_to_cpu(leaf, &pk, slot);
955 					if (pk.offset < bytenr ||
956 					    pk.type != BTRFS_EXTENT_CSUM_KEY ||
957 					    pk.objectid !=
958 					    BTRFS_EXTENT_CSUM_OBJECTID)
959 						break;
960 					path->slots[0] = slot;
961 					del_nr++;
962 					key.offset = pk.offset;
963 					slot--;
964 				}
965 			}
966 			ret = btrfs_del_items(trans, root, path,
967 					      path->slots[0], del_nr);
968 			if (ret)
969 				break;
970 			if (key.offset == bytenr)
971 				break;
972 		} else if (key.offset < bytenr && csum_end > end_byte) {
973 			unsigned long offset;
974 			unsigned long shift_len;
975 			unsigned long item_offset;
976 			/*
977 			 *        [ bytenr - len ]
978 			 *     [csum                ]
979 			 *
980 			 * Our bytes are in the middle of the csum,
981 			 * we need to split this item and insert a new one.
982 			 *
983 			 * But we can't drop the path because the
984 			 * csum could change, get removed, extended etc.
985 			 *
986 			 * The trick here is the max size of a csum item leaves
987 			 * enough room in the tree block for a single
988 			 * item header.  So, we split the item in place,
989 			 * adding a new header pointing to the existing
990 			 * bytes.  Then we loop around again and we have
991 			 * a nicely formed csum item that we can neatly
992 			 * truncate.
993 			 */
994 			offset = (bytenr - key.offset) >> blocksize_bits;
995 			offset *= csum_size;
996 
997 			shift_len = (len >> blocksize_bits) * csum_size;
998 
999 			item_offset = btrfs_item_ptr_offset(leaf,
1000 							    path->slots[0]);
1001 
1002 			memzero_extent_buffer(leaf, item_offset + offset,
1003 					     shift_len);
1004 			key.offset = bytenr;
1005 
1006 			/*
1007 			 * btrfs_split_item returns -EAGAIN when the
1008 			 * item changed size or key
1009 			 */
1010 			ret = btrfs_split_item(trans, root, path, &key, offset);
1011 			if (ret && ret != -EAGAIN) {
1012 				btrfs_abort_transaction(trans, ret);
1013 				break;
1014 			}
1015 			ret = 0;
1016 
1017 			key.offset = end_byte - 1;
1018 		} else {
1019 			truncate_one_csum(fs_info, path, &key, bytenr, len);
1020 			if (key.offset < bytenr)
1021 				break;
1022 		}
1023 		btrfs_release_path(path);
1024 	}
1025 	btrfs_free_path(path);
1026 	return ret;
1027 }
1028 
1029 static int find_next_csum_offset(struct btrfs_root *root,
1030 				 struct btrfs_path *path,
1031 				 u64 *next_offset)
1032 {
1033 	const u32 nritems = btrfs_header_nritems(path->nodes[0]);
1034 	struct btrfs_key found_key;
1035 	int slot = path->slots[0] + 1;
1036 	int ret;
1037 
1038 	if (nritems == 0 || slot >= nritems) {
1039 		ret = btrfs_next_leaf(root, path);
1040 		if (ret < 0) {
1041 			return ret;
1042 		} else if (ret > 0) {
1043 			*next_offset = (u64)-1;
1044 			return 0;
1045 		}
1046 		slot = path->slots[0];
1047 	}
1048 
1049 	btrfs_item_key_to_cpu(path->nodes[0], &found_key, slot);
1050 
1051 	if (found_key.objectid != BTRFS_EXTENT_CSUM_OBJECTID ||
1052 	    found_key.type != BTRFS_EXTENT_CSUM_KEY)
1053 		*next_offset = (u64)-1;
1054 	else
1055 		*next_offset = found_key.offset;
1056 
1057 	return 0;
1058 }
1059 
1060 int btrfs_csum_file_blocks(struct btrfs_trans_handle *trans,
1061 			   struct btrfs_root *root,
1062 			   struct btrfs_ordered_sum *sums)
1063 {
1064 	struct btrfs_fs_info *fs_info = root->fs_info;
1065 	struct btrfs_key file_key;
1066 	struct btrfs_key found_key;
1067 	struct btrfs_path *path;
1068 	struct btrfs_csum_item *item;
1069 	struct btrfs_csum_item *item_end;
1070 	struct extent_buffer *leaf = NULL;
1071 	u64 next_offset;
1072 	u64 total_bytes = 0;
1073 	u64 csum_offset;
1074 	u64 bytenr;
1075 	u32 ins_size;
1076 	int index = 0;
1077 	int found_next;
1078 	int ret;
1079 	const u32 csum_size = fs_info->csum_size;
1080 
1081 	path = btrfs_alloc_path();
1082 	if (!path)
1083 		return -ENOMEM;
1084 again:
1085 	next_offset = (u64)-1;
1086 	found_next = 0;
1087 	bytenr = sums->bytenr + total_bytes;
1088 	file_key.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
1089 	file_key.offset = bytenr;
1090 	file_key.type = BTRFS_EXTENT_CSUM_KEY;
1091 
1092 	item = btrfs_lookup_csum(trans, root, path, bytenr, 1);
1093 	if (!IS_ERR(item)) {
1094 		ret = 0;
1095 		leaf = path->nodes[0];
1096 		item_end = btrfs_item_ptr(leaf, path->slots[0],
1097 					  struct btrfs_csum_item);
1098 		item_end = (struct btrfs_csum_item *)((char *)item_end +
1099 			   btrfs_item_size(leaf, path->slots[0]));
1100 		goto found;
1101 	}
1102 	ret = PTR_ERR(item);
1103 	if (ret != -EFBIG && ret != -ENOENT)
1104 		goto out;
1105 
1106 	if (ret == -EFBIG) {
1107 		u32 item_size;
1108 		/* we found one, but it isn't big enough yet */
1109 		leaf = path->nodes[0];
1110 		item_size = btrfs_item_size(leaf, path->slots[0]);
1111 		if ((item_size / csum_size) >=
1112 		    MAX_CSUM_ITEMS(fs_info, csum_size)) {
1113 			/* already at max size, make a new one */
1114 			goto insert;
1115 		}
1116 	} else {
1117 		/* We didn't find a csum item, insert one. */
1118 		ret = find_next_csum_offset(root, path, &next_offset);
1119 		if (ret < 0)
1120 			goto out;
1121 		found_next = 1;
1122 		goto insert;
1123 	}
1124 
1125 	/*
1126 	 * At this point, we know the tree has a checksum item that ends at an
1127 	 * offset matching the start of the checksum range we want to insert.
1128 	 * We try to extend that item as much as possible and then add as many
1129 	 * checksums to it as they fit.
1130 	 *
1131 	 * First check if the leaf has enough free space for at least one
1132 	 * checksum. If it has go directly to the item extension code, otherwise
1133 	 * release the path and do a search for insertion before the extension.
1134 	 */
1135 	if (btrfs_leaf_free_space(leaf) >= csum_size) {
1136 		btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
1137 		csum_offset = (bytenr - found_key.offset) >>
1138 			fs_info->sectorsize_bits;
1139 		goto extend_csum;
1140 	}
1141 
1142 	btrfs_release_path(path);
1143 	path->search_for_extension = 1;
1144 	ret = btrfs_search_slot(trans, root, &file_key, path,
1145 				csum_size, 1);
1146 	path->search_for_extension = 0;
1147 	if (ret < 0)
1148 		goto out;
1149 
1150 	if (ret > 0) {
1151 		if (path->slots[0] == 0)
1152 			goto insert;
1153 		path->slots[0]--;
1154 	}
1155 
1156 	leaf = path->nodes[0];
1157 	btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
1158 	csum_offset = (bytenr - found_key.offset) >> fs_info->sectorsize_bits;
1159 
1160 	if (found_key.type != BTRFS_EXTENT_CSUM_KEY ||
1161 	    found_key.objectid != BTRFS_EXTENT_CSUM_OBJECTID ||
1162 	    csum_offset >= MAX_CSUM_ITEMS(fs_info, csum_size)) {
1163 		goto insert;
1164 	}
1165 
1166 extend_csum:
1167 	if (csum_offset == btrfs_item_size(leaf, path->slots[0]) /
1168 	    csum_size) {
1169 		int extend_nr;
1170 		u64 tmp;
1171 		u32 diff;
1172 
1173 		tmp = sums->len - total_bytes;
1174 		tmp >>= fs_info->sectorsize_bits;
1175 		WARN_ON(tmp < 1);
1176 		extend_nr = max_t(int, 1, tmp);
1177 
1178 		/*
1179 		 * A log tree can already have checksum items with a subset of
1180 		 * the checksums we are trying to log. This can happen after
1181 		 * doing a sequence of partial writes into prealloc extents and
1182 		 * fsyncs in between, with a full fsync logging a larger subrange
1183 		 * of an extent for which a previous fast fsync logged a smaller
1184 		 * subrange. And this happens in particular due to merging file
1185 		 * extent items when we complete an ordered extent for a range
1186 		 * covered by a prealloc extent - this is done at
1187 		 * btrfs_mark_extent_written().
1188 		 *
1189 		 * So if we try to extend the previous checksum item, which has
1190 		 * a range that ends at the start of the range we want to insert,
1191 		 * make sure we don't extend beyond the start offset of the next
1192 		 * checksum item. If we are at the last item in the leaf, then
1193 		 * forget the optimization of extending and add a new checksum
1194 		 * item - it is not worth the complexity of releasing the path,
1195 		 * getting the first key for the next leaf, repeat the btree
1196 		 * search, etc, because log trees are temporary anyway and it
1197 		 * would only save a few bytes of leaf space.
1198 		 */
1199 		if (root->root_key.objectid == BTRFS_TREE_LOG_OBJECTID) {
1200 			if (path->slots[0] + 1 >=
1201 			    btrfs_header_nritems(path->nodes[0])) {
1202 				ret = find_next_csum_offset(root, path, &next_offset);
1203 				if (ret < 0)
1204 					goto out;
1205 				found_next = 1;
1206 				goto insert;
1207 			}
1208 
1209 			ret = find_next_csum_offset(root, path, &next_offset);
1210 			if (ret < 0)
1211 				goto out;
1212 
1213 			tmp = (next_offset - bytenr) >> fs_info->sectorsize_bits;
1214 			if (tmp <= INT_MAX)
1215 				extend_nr = min_t(int, extend_nr, tmp);
1216 		}
1217 
1218 		diff = (csum_offset + extend_nr) * csum_size;
1219 		diff = min(diff,
1220 			   MAX_CSUM_ITEMS(fs_info, csum_size) * csum_size);
1221 
1222 		diff = diff - btrfs_item_size(leaf, path->slots[0]);
1223 		diff = min_t(u32, btrfs_leaf_free_space(leaf), diff);
1224 		diff /= csum_size;
1225 		diff *= csum_size;
1226 
1227 		btrfs_extend_item(path, diff);
1228 		ret = 0;
1229 		goto csum;
1230 	}
1231 
1232 insert:
1233 	btrfs_release_path(path);
1234 	csum_offset = 0;
1235 	if (found_next) {
1236 		u64 tmp;
1237 
1238 		tmp = sums->len - total_bytes;
1239 		tmp >>= fs_info->sectorsize_bits;
1240 		tmp = min(tmp, (next_offset - file_key.offset) >>
1241 					 fs_info->sectorsize_bits);
1242 
1243 		tmp = max_t(u64, 1, tmp);
1244 		tmp = min_t(u64, tmp, MAX_CSUM_ITEMS(fs_info, csum_size));
1245 		ins_size = csum_size * tmp;
1246 	} else {
1247 		ins_size = csum_size;
1248 	}
1249 	ret = btrfs_insert_empty_item(trans, root, path, &file_key,
1250 				      ins_size);
1251 	if (ret < 0)
1252 		goto out;
1253 	if (WARN_ON(ret != 0))
1254 		goto out;
1255 	leaf = path->nodes[0];
1256 csum:
1257 	item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_csum_item);
1258 	item_end = (struct btrfs_csum_item *)((unsigned char *)item +
1259 				      btrfs_item_size(leaf, path->slots[0]));
1260 	item = (struct btrfs_csum_item *)((unsigned char *)item +
1261 					  csum_offset * csum_size);
1262 found:
1263 	ins_size = (u32)(sums->len - total_bytes) >> fs_info->sectorsize_bits;
1264 	ins_size *= csum_size;
1265 	ins_size = min_t(u32, (unsigned long)item_end - (unsigned long)item,
1266 			      ins_size);
1267 	write_extent_buffer(leaf, sums->sums + index, (unsigned long)item,
1268 			    ins_size);
1269 
1270 	index += ins_size;
1271 	ins_size /= csum_size;
1272 	total_bytes += ins_size * fs_info->sectorsize;
1273 
1274 	btrfs_mark_buffer_dirty(path->nodes[0]);
1275 	if (total_bytes < sums->len) {
1276 		btrfs_release_path(path);
1277 		cond_resched();
1278 		goto again;
1279 	}
1280 out:
1281 	btrfs_free_path(path);
1282 	return ret;
1283 }
1284 
1285 void btrfs_extent_item_to_extent_map(struct btrfs_inode *inode,
1286 				     const struct btrfs_path *path,
1287 				     struct btrfs_file_extent_item *fi,
1288 				     struct extent_map *em)
1289 {
1290 	struct btrfs_fs_info *fs_info = inode->root->fs_info;
1291 	struct btrfs_root *root = inode->root;
1292 	struct extent_buffer *leaf = path->nodes[0];
1293 	const int slot = path->slots[0];
1294 	struct btrfs_key key;
1295 	u64 extent_start, extent_end;
1296 	u64 bytenr;
1297 	u8 type = btrfs_file_extent_type(leaf, fi);
1298 	int compress_type = btrfs_file_extent_compression(leaf, fi);
1299 
1300 	btrfs_item_key_to_cpu(leaf, &key, slot);
1301 	extent_start = key.offset;
1302 	extent_end = btrfs_file_extent_end(path);
1303 	em->ram_bytes = btrfs_file_extent_ram_bytes(leaf, fi);
1304 	em->generation = btrfs_file_extent_generation(leaf, fi);
1305 	if (type == BTRFS_FILE_EXTENT_REG ||
1306 	    type == BTRFS_FILE_EXTENT_PREALLOC) {
1307 		em->start = extent_start;
1308 		em->len = extent_end - extent_start;
1309 		em->orig_start = extent_start -
1310 			btrfs_file_extent_offset(leaf, fi);
1311 		em->orig_block_len = btrfs_file_extent_disk_num_bytes(leaf, fi);
1312 		bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
1313 		if (bytenr == 0) {
1314 			em->block_start = EXTENT_MAP_HOLE;
1315 			return;
1316 		}
1317 		if (compress_type != BTRFS_COMPRESS_NONE) {
1318 			set_bit(EXTENT_FLAG_COMPRESSED, &em->flags);
1319 			em->compress_type = compress_type;
1320 			em->block_start = bytenr;
1321 			em->block_len = em->orig_block_len;
1322 		} else {
1323 			bytenr += btrfs_file_extent_offset(leaf, fi);
1324 			em->block_start = bytenr;
1325 			em->block_len = em->len;
1326 			if (type == BTRFS_FILE_EXTENT_PREALLOC)
1327 				set_bit(EXTENT_FLAG_PREALLOC, &em->flags);
1328 		}
1329 	} else if (type == BTRFS_FILE_EXTENT_INLINE) {
1330 		em->block_start = EXTENT_MAP_INLINE;
1331 		em->start = extent_start;
1332 		em->len = extent_end - extent_start;
1333 		/*
1334 		 * Initialize orig_start and block_len with the same values
1335 		 * as in inode.c:btrfs_get_extent().
1336 		 */
1337 		em->orig_start = EXTENT_MAP_HOLE;
1338 		em->block_len = (u64)-1;
1339 		em->compress_type = compress_type;
1340 		if (compress_type != BTRFS_COMPRESS_NONE)
1341 			set_bit(EXTENT_FLAG_COMPRESSED, &em->flags);
1342 	} else {
1343 		btrfs_err(fs_info,
1344 			  "unknown file extent item type %d, inode %llu, offset %llu, "
1345 			  "root %llu", type, btrfs_ino(inode), extent_start,
1346 			  root->root_key.objectid);
1347 	}
1348 }
1349 
1350 /*
1351  * Returns the end offset (non inclusive) of the file extent item the given path
1352  * points to. If it points to an inline extent, the returned offset is rounded
1353  * up to the sector size.
1354  */
1355 u64 btrfs_file_extent_end(const struct btrfs_path *path)
1356 {
1357 	const struct extent_buffer *leaf = path->nodes[0];
1358 	const int slot = path->slots[0];
1359 	struct btrfs_file_extent_item *fi;
1360 	struct btrfs_key key;
1361 	u64 end;
1362 
1363 	btrfs_item_key_to_cpu(leaf, &key, slot);
1364 	ASSERT(key.type == BTRFS_EXTENT_DATA_KEY);
1365 	fi = btrfs_item_ptr(leaf, slot, struct btrfs_file_extent_item);
1366 
1367 	if (btrfs_file_extent_type(leaf, fi) == BTRFS_FILE_EXTENT_INLINE) {
1368 		end = btrfs_file_extent_ram_bytes(leaf, fi);
1369 		end = ALIGN(key.offset + end, leaf->fs_info->sectorsize);
1370 	} else {
1371 		end = key.offset + btrfs_file_extent_num_bytes(leaf, fi);
1372 	}
1373 
1374 	return end;
1375 }
1376