xref: /linux/fs/btrfs/file-item.c (revision e5c86679d5e864947a52fb31e45a425dea3e7fa9)
1 /*
2  * Copyright (C) 2007 Oracle.  All rights reserved.
3  *
4  * This program is free software; you can redistribute it and/or
5  * modify it under the terms of the GNU General Public
6  * License v2 as published by the Free Software Foundation.
7  *
8  * This program is distributed in the hope that it will be useful,
9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
11  * General Public License for more details.
12  *
13  * You should have received a copy of the GNU General Public
14  * License along with this program; if not, write to the
15  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
16  * Boston, MA 021110-1307, USA.
17  */
18 
19 #include <linux/bio.h>
20 #include <linux/slab.h>
21 #include <linux/pagemap.h>
22 #include <linux/highmem.h>
23 #include "ctree.h"
24 #include "disk-io.h"
25 #include "transaction.h"
26 #include "volumes.h"
27 #include "print-tree.h"
28 #include "compression.h"
29 
30 #define __MAX_CSUM_ITEMS(r, size) ((unsigned long)(((BTRFS_LEAF_DATA_SIZE(r) - \
31 				   sizeof(struct btrfs_item) * 2) / \
32 				  size) - 1))
33 
34 #define MAX_CSUM_ITEMS(r, size) (min_t(u32, __MAX_CSUM_ITEMS(r, size), \
35 				       PAGE_SIZE))
36 
37 #define MAX_ORDERED_SUM_BYTES(fs_info) ((PAGE_SIZE - \
38 				   sizeof(struct btrfs_ordered_sum)) / \
39 				   sizeof(u32) * (fs_info)->sectorsize)
40 
41 int btrfs_insert_file_extent(struct btrfs_trans_handle *trans,
42 			     struct btrfs_root *root,
43 			     u64 objectid, u64 pos,
44 			     u64 disk_offset, u64 disk_num_bytes,
45 			     u64 num_bytes, u64 offset, u64 ram_bytes,
46 			     u8 compression, u8 encryption, u16 other_encoding)
47 {
48 	int ret = 0;
49 	struct btrfs_file_extent_item *item;
50 	struct btrfs_key file_key;
51 	struct btrfs_path *path;
52 	struct extent_buffer *leaf;
53 
54 	path = btrfs_alloc_path();
55 	if (!path)
56 		return -ENOMEM;
57 	file_key.objectid = objectid;
58 	file_key.offset = pos;
59 	file_key.type = BTRFS_EXTENT_DATA_KEY;
60 
61 	path->leave_spinning = 1;
62 	ret = btrfs_insert_empty_item(trans, root, path, &file_key,
63 				      sizeof(*item));
64 	if (ret < 0)
65 		goto out;
66 	BUG_ON(ret); /* Can't happen */
67 	leaf = path->nodes[0];
68 	item = btrfs_item_ptr(leaf, path->slots[0],
69 			      struct btrfs_file_extent_item);
70 	btrfs_set_file_extent_disk_bytenr(leaf, item, disk_offset);
71 	btrfs_set_file_extent_disk_num_bytes(leaf, item, disk_num_bytes);
72 	btrfs_set_file_extent_offset(leaf, item, offset);
73 	btrfs_set_file_extent_num_bytes(leaf, item, num_bytes);
74 	btrfs_set_file_extent_ram_bytes(leaf, item, ram_bytes);
75 	btrfs_set_file_extent_generation(leaf, item, trans->transid);
76 	btrfs_set_file_extent_type(leaf, item, BTRFS_FILE_EXTENT_REG);
77 	btrfs_set_file_extent_compression(leaf, item, compression);
78 	btrfs_set_file_extent_encryption(leaf, item, encryption);
79 	btrfs_set_file_extent_other_encoding(leaf, item, other_encoding);
80 
81 	btrfs_mark_buffer_dirty(leaf);
82 out:
83 	btrfs_free_path(path);
84 	return ret;
85 }
86 
87 static struct btrfs_csum_item *
88 btrfs_lookup_csum(struct btrfs_trans_handle *trans,
89 		  struct btrfs_root *root,
90 		  struct btrfs_path *path,
91 		  u64 bytenr, int cow)
92 {
93 	struct btrfs_fs_info *fs_info = root->fs_info;
94 	int ret;
95 	struct btrfs_key file_key;
96 	struct btrfs_key found_key;
97 	struct btrfs_csum_item *item;
98 	struct extent_buffer *leaf;
99 	u64 csum_offset = 0;
100 	u16 csum_size = btrfs_super_csum_size(fs_info->super_copy);
101 	int csums_in_item;
102 
103 	file_key.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
104 	file_key.offset = bytenr;
105 	file_key.type = BTRFS_EXTENT_CSUM_KEY;
106 	ret = btrfs_search_slot(trans, root, &file_key, path, 0, cow);
107 	if (ret < 0)
108 		goto fail;
109 	leaf = path->nodes[0];
110 	if (ret > 0) {
111 		ret = 1;
112 		if (path->slots[0] == 0)
113 			goto fail;
114 		path->slots[0]--;
115 		btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
116 		if (found_key.type != BTRFS_EXTENT_CSUM_KEY)
117 			goto fail;
118 
119 		csum_offset = (bytenr - found_key.offset) >>
120 				fs_info->sb->s_blocksize_bits;
121 		csums_in_item = btrfs_item_size_nr(leaf, path->slots[0]);
122 		csums_in_item /= csum_size;
123 
124 		if (csum_offset == csums_in_item) {
125 			ret = -EFBIG;
126 			goto fail;
127 		} else if (csum_offset > csums_in_item) {
128 			goto fail;
129 		}
130 	}
131 	item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_csum_item);
132 	item = (struct btrfs_csum_item *)((unsigned char *)item +
133 					  csum_offset * csum_size);
134 	return item;
135 fail:
136 	if (ret > 0)
137 		ret = -ENOENT;
138 	return ERR_PTR(ret);
139 }
140 
141 int btrfs_lookup_file_extent(struct btrfs_trans_handle *trans,
142 			     struct btrfs_root *root,
143 			     struct btrfs_path *path, u64 objectid,
144 			     u64 offset, int mod)
145 {
146 	int ret;
147 	struct btrfs_key file_key;
148 	int ins_len = mod < 0 ? -1 : 0;
149 	int cow = mod != 0;
150 
151 	file_key.objectid = objectid;
152 	file_key.offset = offset;
153 	file_key.type = BTRFS_EXTENT_DATA_KEY;
154 	ret = btrfs_search_slot(trans, root, &file_key, path, ins_len, cow);
155 	return ret;
156 }
157 
158 static void btrfs_io_bio_endio_readpage(struct btrfs_io_bio *bio, int err)
159 {
160 	kfree(bio->csum_allocated);
161 }
162 
163 static int __btrfs_lookup_bio_sums(struct inode *inode, struct bio *bio,
164 				   u64 logical_offset, u32 *dst, int dio)
165 {
166 	struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
167 	struct bio_vec *bvec;
168 	struct btrfs_io_bio *btrfs_bio = btrfs_io_bio(bio);
169 	struct btrfs_csum_item *item = NULL;
170 	struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree;
171 	struct btrfs_path *path;
172 	u8 *csum;
173 	u64 offset = 0;
174 	u64 item_start_offset = 0;
175 	u64 item_last_offset = 0;
176 	u64 disk_bytenr;
177 	u64 page_bytes_left;
178 	u32 diff;
179 	int nblocks;
180 	int count = 0, i;
181 	u16 csum_size = btrfs_super_csum_size(fs_info->super_copy);
182 
183 	path = btrfs_alloc_path();
184 	if (!path)
185 		return -ENOMEM;
186 
187 	nblocks = bio->bi_iter.bi_size >> inode->i_sb->s_blocksize_bits;
188 	if (!dst) {
189 		if (nblocks * csum_size > BTRFS_BIO_INLINE_CSUM_SIZE) {
190 			btrfs_bio->csum_allocated = kmalloc_array(nblocks,
191 					csum_size, GFP_NOFS);
192 			if (!btrfs_bio->csum_allocated) {
193 				btrfs_free_path(path);
194 				return -ENOMEM;
195 			}
196 			btrfs_bio->csum = btrfs_bio->csum_allocated;
197 			btrfs_bio->end_io = btrfs_io_bio_endio_readpage;
198 		} else {
199 			btrfs_bio->csum = btrfs_bio->csum_inline;
200 		}
201 		csum = btrfs_bio->csum;
202 	} else {
203 		csum = (u8 *)dst;
204 	}
205 
206 	if (bio->bi_iter.bi_size > PAGE_SIZE * 8)
207 		path->reada = READA_FORWARD;
208 
209 	WARN_ON(bio->bi_vcnt <= 0);
210 
211 	/*
212 	 * the free space stuff is only read when it hasn't been
213 	 * updated in the current transaction.  So, we can safely
214 	 * read from the commit root and sidestep a nasty deadlock
215 	 * between reading the free space cache and updating the csum tree.
216 	 */
217 	if (btrfs_is_free_space_inode(BTRFS_I(inode))) {
218 		path->search_commit_root = 1;
219 		path->skip_locking = 1;
220 	}
221 
222 	disk_bytenr = (u64)bio->bi_iter.bi_sector << 9;
223 	if (dio)
224 		offset = logical_offset;
225 
226 	bio_for_each_segment_all(bvec, bio, i) {
227 		page_bytes_left = bvec->bv_len;
228 		if (count)
229 			goto next;
230 
231 		if (!dio)
232 			offset = page_offset(bvec->bv_page) + bvec->bv_offset;
233 		count = btrfs_find_ordered_sum(inode, offset, disk_bytenr,
234 					       (u32 *)csum, nblocks);
235 		if (count)
236 			goto found;
237 
238 		if (!item || disk_bytenr < item_start_offset ||
239 		    disk_bytenr >= item_last_offset) {
240 			struct btrfs_key found_key;
241 			u32 item_size;
242 
243 			if (item)
244 				btrfs_release_path(path);
245 			item = btrfs_lookup_csum(NULL, fs_info->csum_root,
246 						 path, disk_bytenr, 0);
247 			if (IS_ERR(item)) {
248 				count = 1;
249 				memset(csum, 0, csum_size);
250 				if (BTRFS_I(inode)->root->root_key.objectid ==
251 				    BTRFS_DATA_RELOC_TREE_OBJECTID) {
252 					set_extent_bits(io_tree, offset,
253 						offset + fs_info->sectorsize - 1,
254 						EXTENT_NODATASUM);
255 				} else {
256 					btrfs_info_rl(fs_info,
257 						   "no csum found for inode %llu start %llu",
258 					       btrfs_ino(BTRFS_I(inode)), offset);
259 				}
260 				item = NULL;
261 				btrfs_release_path(path);
262 				goto found;
263 			}
264 			btrfs_item_key_to_cpu(path->nodes[0], &found_key,
265 					      path->slots[0]);
266 
267 			item_start_offset = found_key.offset;
268 			item_size = btrfs_item_size_nr(path->nodes[0],
269 						       path->slots[0]);
270 			item_last_offset = item_start_offset +
271 				(item_size / csum_size) *
272 				fs_info->sectorsize;
273 			item = btrfs_item_ptr(path->nodes[0], path->slots[0],
274 					      struct btrfs_csum_item);
275 		}
276 		/*
277 		 * this byte range must be able to fit inside
278 		 * a single leaf so it will also fit inside a u32
279 		 */
280 		diff = disk_bytenr - item_start_offset;
281 		diff = diff / fs_info->sectorsize;
282 		diff = diff * csum_size;
283 		count = min_t(int, nblocks, (item_last_offset - disk_bytenr) >>
284 					    inode->i_sb->s_blocksize_bits);
285 		read_extent_buffer(path->nodes[0], csum,
286 				   ((unsigned long)item) + diff,
287 				   csum_size * count);
288 found:
289 		csum += count * csum_size;
290 		nblocks -= count;
291 next:
292 		while (count--) {
293 			disk_bytenr += fs_info->sectorsize;
294 			offset += fs_info->sectorsize;
295 			page_bytes_left -= fs_info->sectorsize;
296 			if (!page_bytes_left)
297 				break; /* move to next bio */
298 		}
299 	}
300 
301 	WARN_ON_ONCE(count);
302 	btrfs_free_path(path);
303 	return 0;
304 }
305 
306 int btrfs_lookup_bio_sums(struct inode *inode, struct bio *bio, u32 *dst)
307 {
308 	return __btrfs_lookup_bio_sums(inode, bio, 0, dst, 0);
309 }
310 
311 int btrfs_lookup_bio_sums_dio(struct inode *inode, struct bio *bio, u64 offset)
312 {
313 	return __btrfs_lookup_bio_sums(inode, bio, offset, NULL, 1);
314 }
315 
316 int btrfs_lookup_csums_range(struct btrfs_root *root, u64 start, u64 end,
317 			     struct list_head *list, int search_commit)
318 {
319 	struct btrfs_fs_info *fs_info = root->fs_info;
320 	struct btrfs_key key;
321 	struct btrfs_path *path;
322 	struct extent_buffer *leaf;
323 	struct btrfs_ordered_sum *sums;
324 	struct btrfs_csum_item *item;
325 	LIST_HEAD(tmplist);
326 	unsigned long offset;
327 	int ret;
328 	size_t size;
329 	u64 csum_end;
330 	u16 csum_size = btrfs_super_csum_size(fs_info->super_copy);
331 
332 	ASSERT(IS_ALIGNED(start, fs_info->sectorsize) &&
333 	       IS_ALIGNED(end + 1, fs_info->sectorsize));
334 
335 	path = btrfs_alloc_path();
336 	if (!path)
337 		return -ENOMEM;
338 
339 	if (search_commit) {
340 		path->skip_locking = 1;
341 		path->reada = READA_FORWARD;
342 		path->search_commit_root = 1;
343 	}
344 
345 	key.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
346 	key.offset = start;
347 	key.type = BTRFS_EXTENT_CSUM_KEY;
348 
349 	ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
350 	if (ret < 0)
351 		goto fail;
352 	if (ret > 0 && path->slots[0] > 0) {
353 		leaf = path->nodes[0];
354 		btrfs_item_key_to_cpu(leaf, &key, path->slots[0] - 1);
355 		if (key.objectid == BTRFS_EXTENT_CSUM_OBJECTID &&
356 		    key.type == BTRFS_EXTENT_CSUM_KEY) {
357 			offset = (start - key.offset) >>
358 				 fs_info->sb->s_blocksize_bits;
359 			if (offset * csum_size <
360 			    btrfs_item_size_nr(leaf, path->slots[0] - 1))
361 				path->slots[0]--;
362 		}
363 	}
364 
365 	while (start <= end) {
366 		leaf = path->nodes[0];
367 		if (path->slots[0] >= btrfs_header_nritems(leaf)) {
368 			ret = btrfs_next_leaf(root, path);
369 			if (ret < 0)
370 				goto fail;
371 			if (ret > 0)
372 				break;
373 			leaf = path->nodes[0];
374 		}
375 
376 		btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
377 		if (key.objectid != BTRFS_EXTENT_CSUM_OBJECTID ||
378 		    key.type != BTRFS_EXTENT_CSUM_KEY ||
379 		    key.offset > end)
380 			break;
381 
382 		if (key.offset > start)
383 			start = key.offset;
384 
385 		size = btrfs_item_size_nr(leaf, path->slots[0]);
386 		csum_end = key.offset + (size / csum_size) * fs_info->sectorsize;
387 		if (csum_end <= start) {
388 			path->slots[0]++;
389 			continue;
390 		}
391 
392 		csum_end = min(csum_end, end + 1);
393 		item = btrfs_item_ptr(path->nodes[0], path->slots[0],
394 				      struct btrfs_csum_item);
395 		while (start < csum_end) {
396 			size = min_t(size_t, csum_end - start,
397 				     MAX_ORDERED_SUM_BYTES(fs_info));
398 			sums = kzalloc(btrfs_ordered_sum_size(fs_info, size),
399 				       GFP_NOFS);
400 			if (!sums) {
401 				ret = -ENOMEM;
402 				goto fail;
403 			}
404 
405 			sums->bytenr = start;
406 			sums->len = (int)size;
407 
408 			offset = (start - key.offset) >>
409 				fs_info->sb->s_blocksize_bits;
410 			offset *= csum_size;
411 			size >>= fs_info->sb->s_blocksize_bits;
412 
413 			read_extent_buffer(path->nodes[0],
414 					   sums->sums,
415 					   ((unsigned long)item) + offset,
416 					   csum_size * size);
417 
418 			start += fs_info->sectorsize * size;
419 			list_add_tail(&sums->list, &tmplist);
420 		}
421 		path->slots[0]++;
422 	}
423 	ret = 0;
424 fail:
425 	while (ret < 0 && !list_empty(&tmplist)) {
426 		sums = list_entry(tmplist.next, struct btrfs_ordered_sum, list);
427 		list_del(&sums->list);
428 		kfree(sums);
429 	}
430 	list_splice_tail(&tmplist, list);
431 
432 	btrfs_free_path(path);
433 	return ret;
434 }
435 
436 int btrfs_csum_one_bio(struct inode *inode, struct bio *bio,
437 		       u64 file_start, int contig)
438 {
439 	struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
440 	struct btrfs_ordered_sum *sums;
441 	struct btrfs_ordered_extent *ordered = NULL;
442 	char *data;
443 	struct bio_vec *bvec;
444 	int index;
445 	int nr_sectors;
446 	int i, j;
447 	unsigned long total_bytes = 0;
448 	unsigned long this_sum_bytes = 0;
449 	u64 offset;
450 
451 	WARN_ON(bio->bi_vcnt <= 0);
452 	sums = kzalloc(btrfs_ordered_sum_size(fs_info, bio->bi_iter.bi_size),
453 		       GFP_NOFS);
454 	if (!sums)
455 		return -ENOMEM;
456 
457 	sums->len = bio->bi_iter.bi_size;
458 	INIT_LIST_HEAD(&sums->list);
459 
460 	if (contig)
461 		offset = file_start;
462 	else
463 		offset = 0; /* shut up gcc */
464 
465 	sums->bytenr = (u64)bio->bi_iter.bi_sector << 9;
466 	index = 0;
467 
468 	bio_for_each_segment_all(bvec, bio, j) {
469 		if (!contig)
470 			offset = page_offset(bvec->bv_page) + bvec->bv_offset;
471 
472 		if (!ordered) {
473 			ordered = btrfs_lookup_ordered_extent(inode, offset);
474 			BUG_ON(!ordered); /* Logic error */
475 		}
476 
477 		data = kmap_atomic(bvec->bv_page);
478 
479 		nr_sectors = BTRFS_BYTES_TO_BLKS(fs_info,
480 						 bvec->bv_len + fs_info->sectorsize
481 						 - 1);
482 
483 		for (i = 0; i < nr_sectors; i++) {
484 			if (offset >= ordered->file_offset + ordered->len ||
485 				offset < ordered->file_offset) {
486 				unsigned long bytes_left;
487 
488 				kunmap_atomic(data);
489 				sums->len = this_sum_bytes;
490 				this_sum_bytes = 0;
491 				btrfs_add_ordered_sum(inode, ordered, sums);
492 				btrfs_put_ordered_extent(ordered);
493 
494 				bytes_left = bio->bi_iter.bi_size - total_bytes;
495 
496 				sums = kzalloc(btrfs_ordered_sum_size(fs_info, bytes_left),
497 					       GFP_NOFS);
498 				BUG_ON(!sums); /* -ENOMEM */
499 				sums->len = bytes_left;
500 				ordered = btrfs_lookup_ordered_extent(inode,
501 								offset);
502 				ASSERT(ordered); /* Logic error */
503 				sums->bytenr = ((u64)bio->bi_iter.bi_sector << 9)
504 					+ total_bytes;
505 				index = 0;
506 
507 				data = kmap_atomic(bvec->bv_page);
508 			}
509 
510 			sums->sums[index] = ~(u32)0;
511 			sums->sums[index]
512 				= btrfs_csum_data(data + bvec->bv_offset
513 						+ (i * fs_info->sectorsize),
514 						sums->sums[index],
515 						fs_info->sectorsize);
516 			btrfs_csum_final(sums->sums[index],
517 					(char *)(sums->sums + index));
518 			index++;
519 			offset += fs_info->sectorsize;
520 			this_sum_bytes += fs_info->sectorsize;
521 			total_bytes += fs_info->sectorsize;
522 		}
523 
524 		kunmap_atomic(data);
525 	}
526 	this_sum_bytes = 0;
527 	btrfs_add_ordered_sum(inode, ordered, sums);
528 	btrfs_put_ordered_extent(ordered);
529 	return 0;
530 }
531 
532 /*
533  * helper function for csum removal, this expects the
534  * key to describe the csum pointed to by the path, and it expects
535  * the csum to overlap the range [bytenr, len]
536  *
537  * The csum should not be entirely contained in the range and the
538  * range should not be entirely contained in the csum.
539  *
540  * This calls btrfs_truncate_item with the correct args based on the
541  * overlap, and fixes up the key as required.
542  */
543 static noinline void truncate_one_csum(struct btrfs_fs_info *fs_info,
544 				       struct btrfs_path *path,
545 				       struct btrfs_key *key,
546 				       u64 bytenr, u64 len)
547 {
548 	struct extent_buffer *leaf;
549 	u16 csum_size = btrfs_super_csum_size(fs_info->super_copy);
550 	u64 csum_end;
551 	u64 end_byte = bytenr + len;
552 	u32 blocksize_bits = fs_info->sb->s_blocksize_bits;
553 
554 	leaf = path->nodes[0];
555 	csum_end = btrfs_item_size_nr(leaf, path->slots[0]) / csum_size;
556 	csum_end <<= fs_info->sb->s_blocksize_bits;
557 	csum_end += key->offset;
558 
559 	if (key->offset < bytenr && csum_end <= end_byte) {
560 		/*
561 		 *         [ bytenr - len ]
562 		 *         [   ]
563 		 *   [csum     ]
564 		 *   A simple truncate off the end of the item
565 		 */
566 		u32 new_size = (bytenr - key->offset) >> blocksize_bits;
567 		new_size *= csum_size;
568 		btrfs_truncate_item(fs_info, path, new_size, 1);
569 	} else if (key->offset >= bytenr && csum_end > end_byte &&
570 		   end_byte > key->offset) {
571 		/*
572 		 *         [ bytenr - len ]
573 		 *                 [ ]
574 		 *                 [csum     ]
575 		 * we need to truncate from the beginning of the csum
576 		 */
577 		u32 new_size = (csum_end - end_byte) >> blocksize_bits;
578 		new_size *= csum_size;
579 
580 		btrfs_truncate_item(fs_info, path, new_size, 0);
581 
582 		key->offset = end_byte;
583 		btrfs_set_item_key_safe(fs_info, path, key);
584 	} else {
585 		BUG();
586 	}
587 }
588 
589 /*
590  * deletes the csum items from the csum tree for a given
591  * range of bytes.
592  */
593 int btrfs_del_csums(struct btrfs_trans_handle *trans,
594 		    struct btrfs_fs_info *fs_info, u64 bytenr, u64 len)
595 {
596 	struct btrfs_root *root = fs_info->csum_root;
597 	struct btrfs_path *path;
598 	struct btrfs_key key;
599 	u64 end_byte = bytenr + len;
600 	u64 csum_end;
601 	struct extent_buffer *leaf;
602 	int ret;
603 	u16 csum_size = btrfs_super_csum_size(fs_info->super_copy);
604 	int blocksize_bits = fs_info->sb->s_blocksize_bits;
605 
606 	path = btrfs_alloc_path();
607 	if (!path)
608 		return -ENOMEM;
609 
610 	while (1) {
611 		key.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
612 		key.offset = end_byte - 1;
613 		key.type = BTRFS_EXTENT_CSUM_KEY;
614 
615 		path->leave_spinning = 1;
616 		ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
617 		if (ret > 0) {
618 			if (path->slots[0] == 0)
619 				break;
620 			path->slots[0]--;
621 		} else if (ret < 0) {
622 			break;
623 		}
624 
625 		leaf = path->nodes[0];
626 		btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
627 
628 		if (key.objectid != BTRFS_EXTENT_CSUM_OBJECTID ||
629 		    key.type != BTRFS_EXTENT_CSUM_KEY) {
630 			break;
631 		}
632 
633 		if (key.offset >= end_byte)
634 			break;
635 
636 		csum_end = btrfs_item_size_nr(leaf, path->slots[0]) / csum_size;
637 		csum_end <<= blocksize_bits;
638 		csum_end += key.offset;
639 
640 		/* this csum ends before we start, we're done */
641 		if (csum_end <= bytenr)
642 			break;
643 
644 		/* delete the entire item, it is inside our range */
645 		if (key.offset >= bytenr && csum_end <= end_byte) {
646 			int del_nr = 1;
647 
648 			/*
649 			 * Check how many csum items preceding this one in this
650 			 * leaf correspond to our range and then delete them all
651 			 * at once.
652 			 */
653 			if (key.offset > bytenr && path->slots[0] > 0) {
654 				int slot = path->slots[0] - 1;
655 
656 				while (slot >= 0) {
657 					struct btrfs_key pk;
658 
659 					btrfs_item_key_to_cpu(leaf, &pk, slot);
660 					if (pk.offset < bytenr ||
661 					    pk.type != BTRFS_EXTENT_CSUM_KEY ||
662 					    pk.objectid !=
663 					    BTRFS_EXTENT_CSUM_OBJECTID)
664 						break;
665 					path->slots[0] = slot;
666 					del_nr++;
667 					key.offset = pk.offset;
668 					slot--;
669 				}
670 			}
671 			ret = btrfs_del_items(trans, root, path,
672 					      path->slots[0], del_nr);
673 			if (ret)
674 				goto out;
675 			if (key.offset == bytenr)
676 				break;
677 		} else if (key.offset < bytenr && csum_end > end_byte) {
678 			unsigned long offset;
679 			unsigned long shift_len;
680 			unsigned long item_offset;
681 			/*
682 			 *        [ bytenr - len ]
683 			 *     [csum                ]
684 			 *
685 			 * Our bytes are in the middle of the csum,
686 			 * we need to split this item and insert a new one.
687 			 *
688 			 * But we can't drop the path because the
689 			 * csum could change, get removed, extended etc.
690 			 *
691 			 * The trick here is the max size of a csum item leaves
692 			 * enough room in the tree block for a single
693 			 * item header.  So, we split the item in place,
694 			 * adding a new header pointing to the existing
695 			 * bytes.  Then we loop around again and we have
696 			 * a nicely formed csum item that we can neatly
697 			 * truncate.
698 			 */
699 			offset = (bytenr - key.offset) >> blocksize_bits;
700 			offset *= csum_size;
701 
702 			shift_len = (len >> blocksize_bits) * csum_size;
703 
704 			item_offset = btrfs_item_ptr_offset(leaf,
705 							    path->slots[0]);
706 
707 			memzero_extent_buffer(leaf, item_offset + offset,
708 					     shift_len);
709 			key.offset = bytenr;
710 
711 			/*
712 			 * btrfs_split_item returns -EAGAIN when the
713 			 * item changed size or key
714 			 */
715 			ret = btrfs_split_item(trans, root, path, &key, offset);
716 			if (ret && ret != -EAGAIN) {
717 				btrfs_abort_transaction(trans, ret);
718 				goto out;
719 			}
720 
721 			key.offset = end_byte - 1;
722 		} else {
723 			truncate_one_csum(fs_info, path, &key, bytenr, len);
724 			if (key.offset < bytenr)
725 				break;
726 		}
727 		btrfs_release_path(path);
728 	}
729 	ret = 0;
730 out:
731 	btrfs_free_path(path);
732 	return ret;
733 }
734 
735 int btrfs_csum_file_blocks(struct btrfs_trans_handle *trans,
736 			   struct btrfs_root *root,
737 			   struct btrfs_ordered_sum *sums)
738 {
739 	struct btrfs_fs_info *fs_info = root->fs_info;
740 	struct btrfs_key file_key;
741 	struct btrfs_key found_key;
742 	struct btrfs_path *path;
743 	struct btrfs_csum_item *item;
744 	struct btrfs_csum_item *item_end;
745 	struct extent_buffer *leaf = NULL;
746 	u64 next_offset;
747 	u64 total_bytes = 0;
748 	u64 csum_offset;
749 	u64 bytenr;
750 	u32 nritems;
751 	u32 ins_size;
752 	int index = 0;
753 	int found_next;
754 	int ret;
755 	u16 csum_size = btrfs_super_csum_size(fs_info->super_copy);
756 
757 	path = btrfs_alloc_path();
758 	if (!path)
759 		return -ENOMEM;
760 again:
761 	next_offset = (u64)-1;
762 	found_next = 0;
763 	bytenr = sums->bytenr + total_bytes;
764 	file_key.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
765 	file_key.offset = bytenr;
766 	file_key.type = BTRFS_EXTENT_CSUM_KEY;
767 
768 	item = btrfs_lookup_csum(trans, root, path, bytenr, 1);
769 	if (!IS_ERR(item)) {
770 		ret = 0;
771 		leaf = path->nodes[0];
772 		item_end = btrfs_item_ptr(leaf, path->slots[0],
773 					  struct btrfs_csum_item);
774 		item_end = (struct btrfs_csum_item *)((char *)item_end +
775 			   btrfs_item_size_nr(leaf, path->slots[0]));
776 		goto found;
777 	}
778 	ret = PTR_ERR(item);
779 	if (ret != -EFBIG && ret != -ENOENT)
780 		goto fail_unlock;
781 
782 	if (ret == -EFBIG) {
783 		u32 item_size;
784 		/* we found one, but it isn't big enough yet */
785 		leaf = path->nodes[0];
786 		item_size = btrfs_item_size_nr(leaf, path->slots[0]);
787 		if ((item_size / csum_size) >=
788 		    MAX_CSUM_ITEMS(fs_info, csum_size)) {
789 			/* already at max size, make a new one */
790 			goto insert;
791 		}
792 	} else {
793 		int slot = path->slots[0] + 1;
794 		/* we didn't find a csum item, insert one */
795 		nritems = btrfs_header_nritems(path->nodes[0]);
796 		if (!nritems || (path->slots[0] >= nritems - 1)) {
797 			ret = btrfs_next_leaf(root, path);
798 			if (ret == 1)
799 				found_next = 1;
800 			if (ret != 0)
801 				goto insert;
802 			slot = path->slots[0];
803 		}
804 		btrfs_item_key_to_cpu(path->nodes[0], &found_key, slot);
805 		if (found_key.objectid != BTRFS_EXTENT_CSUM_OBJECTID ||
806 		    found_key.type != BTRFS_EXTENT_CSUM_KEY) {
807 			found_next = 1;
808 			goto insert;
809 		}
810 		next_offset = found_key.offset;
811 		found_next = 1;
812 		goto insert;
813 	}
814 
815 	/*
816 	 * at this point, we know the tree has an item, but it isn't big
817 	 * enough yet to put our csum in.  Grow it
818 	 */
819 	btrfs_release_path(path);
820 	ret = btrfs_search_slot(trans, root, &file_key, path,
821 				csum_size, 1);
822 	if (ret < 0)
823 		goto fail_unlock;
824 
825 	if (ret > 0) {
826 		if (path->slots[0] == 0)
827 			goto insert;
828 		path->slots[0]--;
829 	}
830 
831 	leaf = path->nodes[0];
832 	btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
833 	csum_offset = (bytenr - found_key.offset) >>
834 			fs_info->sb->s_blocksize_bits;
835 
836 	if (found_key.type != BTRFS_EXTENT_CSUM_KEY ||
837 	    found_key.objectid != BTRFS_EXTENT_CSUM_OBJECTID ||
838 	    csum_offset >= MAX_CSUM_ITEMS(fs_info, csum_size)) {
839 		goto insert;
840 	}
841 
842 	if (csum_offset == btrfs_item_size_nr(leaf, path->slots[0]) /
843 	    csum_size) {
844 		int extend_nr;
845 		u64 tmp;
846 		u32 diff;
847 		u32 free_space;
848 
849 		if (btrfs_leaf_free_space(fs_info, leaf) <
850 				 sizeof(struct btrfs_item) + csum_size * 2)
851 			goto insert;
852 
853 		free_space = btrfs_leaf_free_space(fs_info, leaf) -
854 					 sizeof(struct btrfs_item) - csum_size;
855 		tmp = sums->len - total_bytes;
856 		tmp >>= fs_info->sb->s_blocksize_bits;
857 		WARN_ON(tmp < 1);
858 
859 		extend_nr = max_t(int, 1, (int)tmp);
860 		diff = (csum_offset + extend_nr) * csum_size;
861 		diff = min(diff,
862 			   MAX_CSUM_ITEMS(fs_info, csum_size) * csum_size);
863 
864 		diff = diff - btrfs_item_size_nr(leaf, path->slots[0]);
865 		diff = min(free_space, diff);
866 		diff /= csum_size;
867 		diff *= csum_size;
868 
869 		btrfs_extend_item(fs_info, path, diff);
870 		ret = 0;
871 		goto csum;
872 	}
873 
874 insert:
875 	btrfs_release_path(path);
876 	csum_offset = 0;
877 	if (found_next) {
878 		u64 tmp;
879 
880 		tmp = sums->len - total_bytes;
881 		tmp >>= fs_info->sb->s_blocksize_bits;
882 		tmp = min(tmp, (next_offset - file_key.offset) >>
883 					 fs_info->sb->s_blocksize_bits);
884 
885 		tmp = max_t(u64, 1, tmp);
886 		tmp = min_t(u64, tmp, MAX_CSUM_ITEMS(fs_info, csum_size));
887 		ins_size = csum_size * tmp;
888 	} else {
889 		ins_size = csum_size;
890 	}
891 	path->leave_spinning = 1;
892 	ret = btrfs_insert_empty_item(trans, root, path, &file_key,
893 				      ins_size);
894 	path->leave_spinning = 0;
895 	if (ret < 0)
896 		goto fail_unlock;
897 	if (WARN_ON(ret != 0))
898 		goto fail_unlock;
899 	leaf = path->nodes[0];
900 csum:
901 	item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_csum_item);
902 	item_end = (struct btrfs_csum_item *)((unsigned char *)item +
903 				      btrfs_item_size_nr(leaf, path->slots[0]));
904 	item = (struct btrfs_csum_item *)((unsigned char *)item +
905 					  csum_offset * csum_size);
906 found:
907 	ins_size = (u32)(sums->len - total_bytes) >>
908 		   fs_info->sb->s_blocksize_bits;
909 	ins_size *= csum_size;
910 	ins_size = min_t(u32, (unsigned long)item_end - (unsigned long)item,
911 			      ins_size);
912 	write_extent_buffer(leaf, sums->sums + index, (unsigned long)item,
913 			    ins_size);
914 
915 	ins_size /= csum_size;
916 	total_bytes += ins_size * fs_info->sectorsize;
917 	index += ins_size;
918 
919 	btrfs_mark_buffer_dirty(path->nodes[0]);
920 	if (total_bytes < sums->len) {
921 		btrfs_release_path(path);
922 		cond_resched();
923 		goto again;
924 	}
925 out:
926 	btrfs_free_path(path);
927 	return ret;
928 
929 fail_unlock:
930 	goto out;
931 }
932 
933 void btrfs_extent_item_to_extent_map(struct btrfs_inode *inode,
934 				     const struct btrfs_path *path,
935 				     struct btrfs_file_extent_item *fi,
936 				     const bool new_inline,
937 				     struct extent_map *em)
938 {
939 	struct btrfs_fs_info *fs_info = btrfs_sb(inode->vfs_inode.i_sb);
940 	struct btrfs_root *root = inode->root;
941 	struct extent_buffer *leaf = path->nodes[0];
942 	const int slot = path->slots[0];
943 	struct btrfs_key key;
944 	u64 extent_start, extent_end;
945 	u64 bytenr;
946 	u8 type = btrfs_file_extent_type(leaf, fi);
947 	int compress_type = btrfs_file_extent_compression(leaf, fi);
948 
949 	em->bdev = fs_info->fs_devices->latest_bdev;
950 	btrfs_item_key_to_cpu(leaf, &key, slot);
951 	extent_start = key.offset;
952 
953 	if (type == BTRFS_FILE_EXTENT_REG ||
954 	    type == BTRFS_FILE_EXTENT_PREALLOC) {
955 		extent_end = extent_start +
956 			btrfs_file_extent_num_bytes(leaf, fi);
957 	} else if (type == BTRFS_FILE_EXTENT_INLINE) {
958 		size_t size;
959 		size = btrfs_file_extent_inline_len(leaf, slot, fi);
960 		extent_end = ALIGN(extent_start + size,
961 				   fs_info->sectorsize);
962 	}
963 
964 	em->ram_bytes = btrfs_file_extent_ram_bytes(leaf, fi);
965 	if (type == BTRFS_FILE_EXTENT_REG ||
966 	    type == BTRFS_FILE_EXTENT_PREALLOC) {
967 		em->start = extent_start;
968 		em->len = extent_end - extent_start;
969 		em->orig_start = extent_start -
970 			btrfs_file_extent_offset(leaf, fi);
971 		em->orig_block_len = btrfs_file_extent_disk_num_bytes(leaf, fi);
972 		bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
973 		if (bytenr == 0) {
974 			em->block_start = EXTENT_MAP_HOLE;
975 			return;
976 		}
977 		if (compress_type != BTRFS_COMPRESS_NONE) {
978 			set_bit(EXTENT_FLAG_COMPRESSED, &em->flags);
979 			em->compress_type = compress_type;
980 			em->block_start = bytenr;
981 			em->block_len = em->orig_block_len;
982 		} else {
983 			bytenr += btrfs_file_extent_offset(leaf, fi);
984 			em->block_start = bytenr;
985 			em->block_len = em->len;
986 			if (type == BTRFS_FILE_EXTENT_PREALLOC)
987 				set_bit(EXTENT_FLAG_PREALLOC, &em->flags);
988 		}
989 	} else if (type == BTRFS_FILE_EXTENT_INLINE) {
990 		em->block_start = EXTENT_MAP_INLINE;
991 		em->start = extent_start;
992 		em->len = extent_end - extent_start;
993 		/*
994 		 * Initialize orig_start and block_len with the same values
995 		 * as in inode.c:btrfs_get_extent().
996 		 */
997 		em->orig_start = EXTENT_MAP_HOLE;
998 		em->block_len = (u64)-1;
999 		if (!new_inline && compress_type != BTRFS_COMPRESS_NONE) {
1000 			set_bit(EXTENT_FLAG_COMPRESSED, &em->flags);
1001 			em->compress_type = compress_type;
1002 		}
1003 	} else {
1004 		btrfs_err(fs_info,
1005 			  "unknown file extent item type %d, inode %llu, offset %llu, "
1006 			  "root %llu", type, btrfs_ino(inode), extent_start,
1007 			  root->root_key.objectid);
1008 	}
1009 }
1010