xref: /openbmc/linux/fs/btrfs/send.c (revision 2d96b44f)
1 /*
2  * Copyright (C) 2012 Alexander Block.  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/bsearch.h>
20 #include <linux/fs.h>
21 #include <linux/file.h>
22 #include <linux/sort.h>
23 #include <linux/mount.h>
24 #include <linux/xattr.h>
25 #include <linux/posix_acl_xattr.h>
26 #include <linux/radix-tree.h>
27 #include <linux/vmalloc.h>
28 #include <linux/string.h>
29 
30 #include "send.h"
31 #include "backref.h"
32 #include "hash.h"
33 #include "locking.h"
34 #include "disk-io.h"
35 #include "btrfs_inode.h"
36 #include "transaction.h"
37 #include "compression.h"
38 
39 /*
40  * A fs_path is a helper to dynamically build path names with unknown size.
41  * It reallocates the internal buffer on demand.
42  * It allows fast adding of path elements on the right side (normal path) and
43  * fast adding to the left side (reversed path). A reversed path can also be
44  * unreversed if needed.
45  */
46 struct fs_path {
47 	union {
48 		struct {
49 			char *start;
50 			char *end;
51 
52 			char *buf;
53 			unsigned short buf_len:15;
54 			unsigned short reversed:1;
55 			char inline_buf[];
56 		};
57 		/*
58 		 * Average path length does not exceed 200 bytes, we'll have
59 		 * better packing in the slab and higher chance to satisfy
60 		 * a allocation later during send.
61 		 */
62 		char pad[256];
63 	};
64 };
65 #define FS_PATH_INLINE_SIZE \
66 	(sizeof(struct fs_path) - offsetof(struct fs_path, inline_buf))
67 
68 
69 /* reused for each extent */
70 struct clone_root {
71 	struct btrfs_root *root;
72 	u64 ino;
73 	u64 offset;
74 
75 	u64 found_refs;
76 };
77 
78 #define SEND_CTX_MAX_NAME_CACHE_SIZE 128
79 #define SEND_CTX_NAME_CACHE_CLEAN_SIZE (SEND_CTX_MAX_NAME_CACHE_SIZE * 2)
80 
81 struct send_ctx {
82 	struct file *send_filp;
83 	loff_t send_off;
84 	char *send_buf;
85 	u32 send_size;
86 	u32 send_max_size;
87 	u64 total_send_size;
88 	u64 cmd_send_size[BTRFS_SEND_C_MAX + 1];
89 	u64 flags;	/* 'flags' member of btrfs_ioctl_send_args is u64 */
90 
91 	struct btrfs_root *send_root;
92 	struct btrfs_root *parent_root;
93 	struct clone_root *clone_roots;
94 	int clone_roots_cnt;
95 
96 	/* current state of the compare_tree call */
97 	struct btrfs_path *left_path;
98 	struct btrfs_path *right_path;
99 	struct btrfs_key *cmp_key;
100 
101 	/*
102 	 * infos of the currently processed inode. In case of deleted inodes,
103 	 * these are the values from the deleted inode.
104 	 */
105 	u64 cur_ino;
106 	u64 cur_inode_gen;
107 	int cur_inode_new;
108 	int cur_inode_new_gen;
109 	int cur_inode_deleted;
110 	u64 cur_inode_size;
111 	u64 cur_inode_mode;
112 	u64 cur_inode_rdev;
113 	u64 cur_inode_last_extent;
114 
115 	u64 send_progress;
116 
117 	struct list_head new_refs;
118 	struct list_head deleted_refs;
119 
120 	struct radix_tree_root name_cache;
121 	struct list_head name_cache_list;
122 	int name_cache_size;
123 
124 	struct file_ra_state ra;
125 
126 	char *read_buf;
127 
128 	/*
129 	 * We process inodes by their increasing order, so if before an
130 	 * incremental send we reverse the parent/child relationship of
131 	 * directories such that a directory with a lower inode number was
132 	 * the parent of a directory with a higher inode number, and the one
133 	 * becoming the new parent got renamed too, we can't rename/move the
134 	 * directory with lower inode number when we finish processing it - we
135 	 * must process the directory with higher inode number first, then
136 	 * rename/move it and then rename/move the directory with lower inode
137 	 * number. Example follows.
138 	 *
139 	 * Tree state when the first send was performed:
140 	 *
141 	 * .
142 	 * |-- a                   (ino 257)
143 	 *     |-- b               (ino 258)
144 	 *         |
145 	 *         |
146 	 *         |-- c           (ino 259)
147 	 *         |   |-- d       (ino 260)
148 	 *         |
149 	 *         |-- c2          (ino 261)
150 	 *
151 	 * Tree state when the second (incremental) send is performed:
152 	 *
153 	 * .
154 	 * |-- a                   (ino 257)
155 	 *     |-- b               (ino 258)
156 	 *         |-- c2          (ino 261)
157 	 *             |-- d2      (ino 260)
158 	 *                 |-- cc  (ino 259)
159 	 *
160 	 * The sequence of steps that lead to the second state was:
161 	 *
162 	 * mv /a/b/c/d /a/b/c2/d2
163 	 * mv /a/b/c /a/b/c2/d2/cc
164 	 *
165 	 * "c" has lower inode number, but we can't move it (2nd mv operation)
166 	 * before we move "d", which has higher inode number.
167 	 *
168 	 * So we just memorize which move/rename operations must be performed
169 	 * later when their respective parent is processed and moved/renamed.
170 	 */
171 
172 	/* Indexed by parent directory inode number. */
173 	struct rb_root pending_dir_moves;
174 
175 	/*
176 	 * Reverse index, indexed by the inode number of a directory that
177 	 * is waiting for the move/rename of its immediate parent before its
178 	 * own move/rename can be performed.
179 	 */
180 	struct rb_root waiting_dir_moves;
181 
182 	/*
183 	 * A directory that is going to be rm'ed might have a child directory
184 	 * which is in the pending directory moves index above. In this case,
185 	 * the directory can only be removed after the move/rename of its child
186 	 * is performed. Example:
187 	 *
188 	 * Parent snapshot:
189 	 *
190 	 * .                        (ino 256)
191 	 * |-- a/                   (ino 257)
192 	 *     |-- b/               (ino 258)
193 	 *         |-- c/           (ino 259)
194 	 *         |   |-- x/       (ino 260)
195 	 *         |
196 	 *         |-- y/           (ino 261)
197 	 *
198 	 * Send snapshot:
199 	 *
200 	 * .                        (ino 256)
201 	 * |-- a/                   (ino 257)
202 	 *     |-- b/               (ino 258)
203 	 *         |-- YY/          (ino 261)
204 	 *              |-- x/      (ino 260)
205 	 *
206 	 * Sequence of steps that lead to the send snapshot:
207 	 * rm -f /a/b/c/foo.txt
208 	 * mv /a/b/y /a/b/YY
209 	 * mv /a/b/c/x /a/b/YY
210 	 * rmdir /a/b/c
211 	 *
212 	 * When the child is processed, its move/rename is delayed until its
213 	 * parent is processed (as explained above), but all other operations
214 	 * like update utimes, chown, chgrp, etc, are performed and the paths
215 	 * that it uses for those operations must use the orphanized name of
216 	 * its parent (the directory we're going to rm later), so we need to
217 	 * memorize that name.
218 	 *
219 	 * Indexed by the inode number of the directory to be deleted.
220 	 */
221 	struct rb_root orphan_dirs;
222 };
223 
224 struct pending_dir_move {
225 	struct rb_node node;
226 	struct list_head list;
227 	u64 parent_ino;
228 	u64 ino;
229 	u64 gen;
230 	struct list_head update_refs;
231 };
232 
233 struct waiting_dir_move {
234 	struct rb_node node;
235 	u64 ino;
236 	/*
237 	 * There might be some directory that could not be removed because it
238 	 * was waiting for this directory inode to be moved first. Therefore
239 	 * after this directory is moved, we can try to rmdir the ino rmdir_ino.
240 	 */
241 	u64 rmdir_ino;
242 	bool orphanized;
243 };
244 
245 struct orphan_dir_info {
246 	struct rb_node node;
247 	u64 ino;
248 	u64 gen;
249 };
250 
251 struct name_cache_entry {
252 	struct list_head list;
253 	/*
254 	 * radix_tree has only 32bit entries but we need to handle 64bit inums.
255 	 * We use the lower 32bit of the 64bit inum to store it in the tree. If
256 	 * more then one inum would fall into the same entry, we use radix_list
257 	 * to store the additional entries. radix_list is also used to store
258 	 * entries where two entries have the same inum but different
259 	 * generations.
260 	 */
261 	struct list_head radix_list;
262 	u64 ino;
263 	u64 gen;
264 	u64 parent_ino;
265 	u64 parent_gen;
266 	int ret;
267 	int need_later_update;
268 	int name_len;
269 	char name[];
270 };
271 
272 static void inconsistent_snapshot_error(struct send_ctx *sctx,
273 					enum btrfs_compare_tree_result result,
274 					const char *what)
275 {
276 	const char *result_string;
277 
278 	switch (result) {
279 	case BTRFS_COMPARE_TREE_NEW:
280 		result_string = "new";
281 		break;
282 	case BTRFS_COMPARE_TREE_DELETED:
283 		result_string = "deleted";
284 		break;
285 	case BTRFS_COMPARE_TREE_CHANGED:
286 		result_string = "updated";
287 		break;
288 	case BTRFS_COMPARE_TREE_SAME:
289 		ASSERT(0);
290 		result_string = "unchanged";
291 		break;
292 	default:
293 		ASSERT(0);
294 		result_string = "unexpected";
295 	}
296 
297 	btrfs_err(sctx->send_root->fs_info,
298 		  "Send: inconsistent snapshot, found %s %s for inode %llu without updated inode item, send root is %llu, parent root is %llu",
299 		  result_string, what, sctx->cmp_key->objectid,
300 		  sctx->send_root->root_key.objectid,
301 		  (sctx->parent_root ?
302 		   sctx->parent_root->root_key.objectid : 0));
303 }
304 
305 static int is_waiting_for_move(struct send_ctx *sctx, u64 ino);
306 
307 static struct waiting_dir_move *
308 get_waiting_dir_move(struct send_ctx *sctx, u64 ino);
309 
310 static int is_waiting_for_rm(struct send_ctx *sctx, u64 dir_ino);
311 
312 static int need_send_hole(struct send_ctx *sctx)
313 {
314 	return (sctx->parent_root && !sctx->cur_inode_new &&
315 		!sctx->cur_inode_new_gen && !sctx->cur_inode_deleted &&
316 		S_ISREG(sctx->cur_inode_mode));
317 }
318 
319 static void fs_path_reset(struct fs_path *p)
320 {
321 	if (p->reversed) {
322 		p->start = p->buf + p->buf_len - 1;
323 		p->end = p->start;
324 		*p->start = 0;
325 	} else {
326 		p->start = p->buf;
327 		p->end = p->start;
328 		*p->start = 0;
329 	}
330 }
331 
332 static struct fs_path *fs_path_alloc(void)
333 {
334 	struct fs_path *p;
335 
336 	p = kmalloc(sizeof(*p), GFP_KERNEL);
337 	if (!p)
338 		return NULL;
339 	p->reversed = 0;
340 	p->buf = p->inline_buf;
341 	p->buf_len = FS_PATH_INLINE_SIZE;
342 	fs_path_reset(p);
343 	return p;
344 }
345 
346 static struct fs_path *fs_path_alloc_reversed(void)
347 {
348 	struct fs_path *p;
349 
350 	p = fs_path_alloc();
351 	if (!p)
352 		return NULL;
353 	p->reversed = 1;
354 	fs_path_reset(p);
355 	return p;
356 }
357 
358 static void fs_path_free(struct fs_path *p)
359 {
360 	if (!p)
361 		return;
362 	if (p->buf != p->inline_buf)
363 		kfree(p->buf);
364 	kfree(p);
365 }
366 
367 static int fs_path_len(struct fs_path *p)
368 {
369 	return p->end - p->start;
370 }
371 
372 static int fs_path_ensure_buf(struct fs_path *p, int len)
373 {
374 	char *tmp_buf;
375 	int path_len;
376 	int old_buf_len;
377 
378 	len++;
379 
380 	if (p->buf_len >= len)
381 		return 0;
382 
383 	if (len > PATH_MAX) {
384 		WARN_ON(1);
385 		return -ENOMEM;
386 	}
387 
388 	path_len = p->end - p->start;
389 	old_buf_len = p->buf_len;
390 
391 	/*
392 	 * First time the inline_buf does not suffice
393 	 */
394 	if (p->buf == p->inline_buf) {
395 		tmp_buf = kmalloc(len, GFP_KERNEL);
396 		if (tmp_buf)
397 			memcpy(tmp_buf, p->buf, old_buf_len);
398 	} else {
399 		tmp_buf = krealloc(p->buf, len, GFP_KERNEL);
400 	}
401 	if (!tmp_buf)
402 		return -ENOMEM;
403 	p->buf = tmp_buf;
404 	/*
405 	 * The real size of the buffer is bigger, this will let the fast path
406 	 * happen most of the time
407 	 */
408 	p->buf_len = ksize(p->buf);
409 
410 	if (p->reversed) {
411 		tmp_buf = p->buf + old_buf_len - path_len - 1;
412 		p->end = p->buf + p->buf_len - 1;
413 		p->start = p->end - path_len;
414 		memmove(p->start, tmp_buf, path_len + 1);
415 	} else {
416 		p->start = p->buf;
417 		p->end = p->start + path_len;
418 	}
419 	return 0;
420 }
421 
422 static int fs_path_prepare_for_add(struct fs_path *p, int name_len,
423 				   char **prepared)
424 {
425 	int ret;
426 	int new_len;
427 
428 	new_len = p->end - p->start + name_len;
429 	if (p->start != p->end)
430 		new_len++;
431 	ret = fs_path_ensure_buf(p, new_len);
432 	if (ret < 0)
433 		goto out;
434 
435 	if (p->reversed) {
436 		if (p->start != p->end)
437 			*--p->start = '/';
438 		p->start -= name_len;
439 		*prepared = p->start;
440 	} else {
441 		if (p->start != p->end)
442 			*p->end++ = '/';
443 		*prepared = p->end;
444 		p->end += name_len;
445 		*p->end = 0;
446 	}
447 
448 out:
449 	return ret;
450 }
451 
452 static int fs_path_add(struct fs_path *p, const char *name, int name_len)
453 {
454 	int ret;
455 	char *prepared;
456 
457 	ret = fs_path_prepare_for_add(p, name_len, &prepared);
458 	if (ret < 0)
459 		goto out;
460 	memcpy(prepared, name, name_len);
461 
462 out:
463 	return ret;
464 }
465 
466 static int fs_path_add_path(struct fs_path *p, struct fs_path *p2)
467 {
468 	int ret;
469 	char *prepared;
470 
471 	ret = fs_path_prepare_for_add(p, p2->end - p2->start, &prepared);
472 	if (ret < 0)
473 		goto out;
474 	memcpy(prepared, p2->start, p2->end - p2->start);
475 
476 out:
477 	return ret;
478 }
479 
480 static int fs_path_add_from_extent_buffer(struct fs_path *p,
481 					  struct extent_buffer *eb,
482 					  unsigned long off, int len)
483 {
484 	int ret;
485 	char *prepared;
486 
487 	ret = fs_path_prepare_for_add(p, len, &prepared);
488 	if (ret < 0)
489 		goto out;
490 
491 	read_extent_buffer(eb, prepared, off, len);
492 
493 out:
494 	return ret;
495 }
496 
497 static int fs_path_copy(struct fs_path *p, struct fs_path *from)
498 {
499 	int ret;
500 
501 	p->reversed = from->reversed;
502 	fs_path_reset(p);
503 
504 	ret = fs_path_add_path(p, from);
505 
506 	return ret;
507 }
508 
509 
510 static void fs_path_unreverse(struct fs_path *p)
511 {
512 	char *tmp;
513 	int len;
514 
515 	if (!p->reversed)
516 		return;
517 
518 	tmp = p->start;
519 	len = p->end - p->start;
520 	p->start = p->buf;
521 	p->end = p->start + len;
522 	memmove(p->start, tmp, len + 1);
523 	p->reversed = 0;
524 }
525 
526 static struct btrfs_path *alloc_path_for_send(void)
527 {
528 	struct btrfs_path *path;
529 
530 	path = btrfs_alloc_path();
531 	if (!path)
532 		return NULL;
533 	path->search_commit_root = 1;
534 	path->skip_locking = 1;
535 	path->need_commit_sem = 1;
536 	return path;
537 }
538 
539 static int write_buf(struct file *filp, const void *buf, u32 len, loff_t *off)
540 {
541 	int ret;
542 	mm_segment_t old_fs;
543 	u32 pos = 0;
544 
545 	old_fs = get_fs();
546 	set_fs(KERNEL_DS);
547 
548 	while (pos < len) {
549 		ret = vfs_write(filp, (__force const char __user *)buf + pos,
550 				len - pos, off);
551 		/* TODO handle that correctly */
552 		/*if (ret == -ERESTARTSYS) {
553 			continue;
554 		}*/
555 		if (ret < 0)
556 			goto out;
557 		if (ret == 0) {
558 			ret = -EIO;
559 			goto out;
560 		}
561 		pos += ret;
562 	}
563 
564 	ret = 0;
565 
566 out:
567 	set_fs(old_fs);
568 	return ret;
569 }
570 
571 static int tlv_put(struct send_ctx *sctx, u16 attr, const void *data, int len)
572 {
573 	struct btrfs_tlv_header *hdr;
574 	int total_len = sizeof(*hdr) + len;
575 	int left = sctx->send_max_size - sctx->send_size;
576 
577 	if (unlikely(left < total_len))
578 		return -EOVERFLOW;
579 
580 	hdr = (struct btrfs_tlv_header *) (sctx->send_buf + sctx->send_size);
581 	hdr->tlv_type = cpu_to_le16(attr);
582 	hdr->tlv_len = cpu_to_le16(len);
583 	memcpy(hdr + 1, data, len);
584 	sctx->send_size += total_len;
585 
586 	return 0;
587 }
588 
589 #define TLV_PUT_DEFINE_INT(bits) \
590 	static int tlv_put_u##bits(struct send_ctx *sctx,	 	\
591 			u##bits attr, u##bits value)			\
592 	{								\
593 		__le##bits __tmp = cpu_to_le##bits(value);		\
594 		return tlv_put(sctx, attr, &__tmp, sizeof(__tmp));	\
595 	}
596 
597 TLV_PUT_DEFINE_INT(64)
598 
599 static int tlv_put_string(struct send_ctx *sctx, u16 attr,
600 			  const char *str, int len)
601 {
602 	if (len == -1)
603 		len = strlen(str);
604 	return tlv_put(sctx, attr, str, len);
605 }
606 
607 static int tlv_put_uuid(struct send_ctx *sctx, u16 attr,
608 			const u8 *uuid)
609 {
610 	return tlv_put(sctx, attr, uuid, BTRFS_UUID_SIZE);
611 }
612 
613 static int tlv_put_btrfs_timespec(struct send_ctx *sctx, u16 attr,
614 				  struct extent_buffer *eb,
615 				  struct btrfs_timespec *ts)
616 {
617 	struct btrfs_timespec bts;
618 	read_extent_buffer(eb, &bts, (unsigned long)ts, sizeof(bts));
619 	return tlv_put(sctx, attr, &bts, sizeof(bts));
620 }
621 
622 
623 #define TLV_PUT(sctx, attrtype, attrlen, data) \
624 	do { \
625 		ret = tlv_put(sctx, attrtype, attrlen, data); \
626 		if (ret < 0) \
627 			goto tlv_put_failure; \
628 	} while (0)
629 
630 #define TLV_PUT_INT(sctx, attrtype, bits, value) \
631 	do { \
632 		ret = tlv_put_u##bits(sctx, attrtype, value); \
633 		if (ret < 0) \
634 			goto tlv_put_failure; \
635 	} while (0)
636 
637 #define TLV_PUT_U8(sctx, attrtype, data) TLV_PUT_INT(sctx, attrtype, 8, data)
638 #define TLV_PUT_U16(sctx, attrtype, data) TLV_PUT_INT(sctx, attrtype, 16, data)
639 #define TLV_PUT_U32(sctx, attrtype, data) TLV_PUT_INT(sctx, attrtype, 32, data)
640 #define TLV_PUT_U64(sctx, attrtype, data) TLV_PUT_INT(sctx, attrtype, 64, data)
641 #define TLV_PUT_STRING(sctx, attrtype, str, len) \
642 	do { \
643 		ret = tlv_put_string(sctx, attrtype, str, len); \
644 		if (ret < 0) \
645 			goto tlv_put_failure; \
646 	} while (0)
647 #define TLV_PUT_PATH(sctx, attrtype, p) \
648 	do { \
649 		ret = tlv_put_string(sctx, attrtype, p->start, \
650 			p->end - p->start); \
651 		if (ret < 0) \
652 			goto tlv_put_failure; \
653 	} while(0)
654 #define TLV_PUT_UUID(sctx, attrtype, uuid) \
655 	do { \
656 		ret = tlv_put_uuid(sctx, attrtype, uuid); \
657 		if (ret < 0) \
658 			goto tlv_put_failure; \
659 	} while (0)
660 #define TLV_PUT_BTRFS_TIMESPEC(sctx, attrtype, eb, ts) \
661 	do { \
662 		ret = tlv_put_btrfs_timespec(sctx, attrtype, eb, ts); \
663 		if (ret < 0) \
664 			goto tlv_put_failure; \
665 	} while (0)
666 
667 static int send_header(struct send_ctx *sctx)
668 {
669 	struct btrfs_stream_header hdr;
670 
671 	strcpy(hdr.magic, BTRFS_SEND_STREAM_MAGIC);
672 	hdr.version = cpu_to_le32(BTRFS_SEND_STREAM_VERSION);
673 
674 	return write_buf(sctx->send_filp, &hdr, sizeof(hdr),
675 					&sctx->send_off);
676 }
677 
678 /*
679  * For each command/item we want to send to userspace, we call this function.
680  */
681 static int begin_cmd(struct send_ctx *sctx, int cmd)
682 {
683 	struct btrfs_cmd_header *hdr;
684 
685 	if (WARN_ON(!sctx->send_buf))
686 		return -EINVAL;
687 
688 	BUG_ON(sctx->send_size);
689 
690 	sctx->send_size += sizeof(*hdr);
691 	hdr = (struct btrfs_cmd_header *)sctx->send_buf;
692 	hdr->cmd = cpu_to_le16(cmd);
693 
694 	return 0;
695 }
696 
697 static int send_cmd(struct send_ctx *sctx)
698 {
699 	int ret;
700 	struct btrfs_cmd_header *hdr;
701 	u32 crc;
702 
703 	hdr = (struct btrfs_cmd_header *)sctx->send_buf;
704 	hdr->len = cpu_to_le32(sctx->send_size - sizeof(*hdr));
705 	hdr->crc = 0;
706 
707 	crc = btrfs_crc32c(0, (unsigned char *)sctx->send_buf, sctx->send_size);
708 	hdr->crc = cpu_to_le32(crc);
709 
710 	ret = write_buf(sctx->send_filp, sctx->send_buf, sctx->send_size,
711 					&sctx->send_off);
712 
713 	sctx->total_send_size += sctx->send_size;
714 	sctx->cmd_send_size[le16_to_cpu(hdr->cmd)] += sctx->send_size;
715 	sctx->send_size = 0;
716 
717 	return ret;
718 }
719 
720 /*
721  * Sends a move instruction to user space
722  */
723 static int send_rename(struct send_ctx *sctx,
724 		     struct fs_path *from, struct fs_path *to)
725 {
726 	struct btrfs_fs_info *fs_info = sctx->send_root->fs_info;
727 	int ret;
728 
729 	btrfs_debug(fs_info, "send_rename %s -> %s", from->start, to->start);
730 
731 	ret = begin_cmd(sctx, BTRFS_SEND_C_RENAME);
732 	if (ret < 0)
733 		goto out;
734 
735 	TLV_PUT_PATH(sctx, BTRFS_SEND_A_PATH, from);
736 	TLV_PUT_PATH(sctx, BTRFS_SEND_A_PATH_TO, to);
737 
738 	ret = send_cmd(sctx);
739 
740 tlv_put_failure:
741 out:
742 	return ret;
743 }
744 
745 /*
746  * Sends a link instruction to user space
747  */
748 static int send_link(struct send_ctx *sctx,
749 		     struct fs_path *path, struct fs_path *lnk)
750 {
751 	struct btrfs_fs_info *fs_info = sctx->send_root->fs_info;
752 	int ret;
753 
754 	btrfs_debug(fs_info, "send_link %s -> %s", path->start, lnk->start);
755 
756 	ret = begin_cmd(sctx, BTRFS_SEND_C_LINK);
757 	if (ret < 0)
758 		goto out;
759 
760 	TLV_PUT_PATH(sctx, BTRFS_SEND_A_PATH, path);
761 	TLV_PUT_PATH(sctx, BTRFS_SEND_A_PATH_LINK, lnk);
762 
763 	ret = send_cmd(sctx);
764 
765 tlv_put_failure:
766 out:
767 	return ret;
768 }
769 
770 /*
771  * Sends an unlink instruction to user space
772  */
773 static int send_unlink(struct send_ctx *sctx, struct fs_path *path)
774 {
775 	struct btrfs_fs_info *fs_info = sctx->send_root->fs_info;
776 	int ret;
777 
778 	btrfs_debug(fs_info, "send_unlink %s", path->start);
779 
780 	ret = begin_cmd(sctx, BTRFS_SEND_C_UNLINK);
781 	if (ret < 0)
782 		goto out;
783 
784 	TLV_PUT_PATH(sctx, BTRFS_SEND_A_PATH, path);
785 
786 	ret = send_cmd(sctx);
787 
788 tlv_put_failure:
789 out:
790 	return ret;
791 }
792 
793 /*
794  * Sends a rmdir instruction to user space
795  */
796 static int send_rmdir(struct send_ctx *sctx, struct fs_path *path)
797 {
798 	struct btrfs_fs_info *fs_info = sctx->send_root->fs_info;
799 	int ret;
800 
801 	btrfs_debug(fs_info, "send_rmdir %s", path->start);
802 
803 	ret = begin_cmd(sctx, BTRFS_SEND_C_RMDIR);
804 	if (ret < 0)
805 		goto out;
806 
807 	TLV_PUT_PATH(sctx, BTRFS_SEND_A_PATH, path);
808 
809 	ret = send_cmd(sctx);
810 
811 tlv_put_failure:
812 out:
813 	return ret;
814 }
815 
816 /*
817  * Helper function to retrieve some fields from an inode item.
818  */
819 static int __get_inode_info(struct btrfs_root *root, struct btrfs_path *path,
820 			  u64 ino, u64 *size, u64 *gen, u64 *mode, u64 *uid,
821 			  u64 *gid, u64 *rdev)
822 {
823 	int ret;
824 	struct btrfs_inode_item *ii;
825 	struct btrfs_key key;
826 
827 	key.objectid = ino;
828 	key.type = BTRFS_INODE_ITEM_KEY;
829 	key.offset = 0;
830 	ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
831 	if (ret) {
832 		if (ret > 0)
833 			ret = -ENOENT;
834 		return ret;
835 	}
836 
837 	ii = btrfs_item_ptr(path->nodes[0], path->slots[0],
838 			struct btrfs_inode_item);
839 	if (size)
840 		*size = btrfs_inode_size(path->nodes[0], ii);
841 	if (gen)
842 		*gen = btrfs_inode_generation(path->nodes[0], ii);
843 	if (mode)
844 		*mode = btrfs_inode_mode(path->nodes[0], ii);
845 	if (uid)
846 		*uid = btrfs_inode_uid(path->nodes[0], ii);
847 	if (gid)
848 		*gid = btrfs_inode_gid(path->nodes[0], ii);
849 	if (rdev)
850 		*rdev = btrfs_inode_rdev(path->nodes[0], ii);
851 
852 	return ret;
853 }
854 
855 static int get_inode_info(struct btrfs_root *root,
856 			  u64 ino, u64 *size, u64 *gen,
857 			  u64 *mode, u64 *uid, u64 *gid,
858 			  u64 *rdev)
859 {
860 	struct btrfs_path *path;
861 	int ret;
862 
863 	path = alloc_path_for_send();
864 	if (!path)
865 		return -ENOMEM;
866 	ret = __get_inode_info(root, path, ino, size, gen, mode, uid, gid,
867 			       rdev);
868 	btrfs_free_path(path);
869 	return ret;
870 }
871 
872 typedef int (*iterate_inode_ref_t)(int num, u64 dir, int index,
873 				   struct fs_path *p,
874 				   void *ctx);
875 
876 /*
877  * Helper function to iterate the entries in ONE btrfs_inode_ref or
878  * btrfs_inode_extref.
879  * The iterate callback may return a non zero value to stop iteration. This can
880  * be a negative value for error codes or 1 to simply stop it.
881  *
882  * path must point to the INODE_REF or INODE_EXTREF when called.
883  */
884 static int iterate_inode_ref(struct btrfs_root *root, struct btrfs_path *path,
885 			     struct btrfs_key *found_key, int resolve,
886 			     iterate_inode_ref_t iterate, void *ctx)
887 {
888 	struct extent_buffer *eb = path->nodes[0];
889 	struct btrfs_item *item;
890 	struct btrfs_inode_ref *iref;
891 	struct btrfs_inode_extref *extref;
892 	struct btrfs_path *tmp_path;
893 	struct fs_path *p;
894 	u32 cur = 0;
895 	u32 total;
896 	int slot = path->slots[0];
897 	u32 name_len;
898 	char *start;
899 	int ret = 0;
900 	int num = 0;
901 	int index;
902 	u64 dir;
903 	unsigned long name_off;
904 	unsigned long elem_size;
905 	unsigned long ptr;
906 
907 	p = fs_path_alloc_reversed();
908 	if (!p)
909 		return -ENOMEM;
910 
911 	tmp_path = alloc_path_for_send();
912 	if (!tmp_path) {
913 		fs_path_free(p);
914 		return -ENOMEM;
915 	}
916 
917 
918 	if (found_key->type == BTRFS_INODE_REF_KEY) {
919 		ptr = (unsigned long)btrfs_item_ptr(eb, slot,
920 						    struct btrfs_inode_ref);
921 		item = btrfs_item_nr(slot);
922 		total = btrfs_item_size(eb, item);
923 		elem_size = sizeof(*iref);
924 	} else {
925 		ptr = btrfs_item_ptr_offset(eb, slot);
926 		total = btrfs_item_size_nr(eb, slot);
927 		elem_size = sizeof(*extref);
928 	}
929 
930 	while (cur < total) {
931 		fs_path_reset(p);
932 
933 		if (found_key->type == BTRFS_INODE_REF_KEY) {
934 			iref = (struct btrfs_inode_ref *)(ptr + cur);
935 			name_len = btrfs_inode_ref_name_len(eb, iref);
936 			name_off = (unsigned long)(iref + 1);
937 			index = btrfs_inode_ref_index(eb, iref);
938 			dir = found_key->offset;
939 		} else {
940 			extref = (struct btrfs_inode_extref *)(ptr + cur);
941 			name_len = btrfs_inode_extref_name_len(eb, extref);
942 			name_off = (unsigned long)&extref->name;
943 			index = btrfs_inode_extref_index(eb, extref);
944 			dir = btrfs_inode_extref_parent(eb, extref);
945 		}
946 
947 		if (resolve) {
948 			start = btrfs_ref_to_path(root, tmp_path, name_len,
949 						  name_off, eb, dir,
950 						  p->buf, p->buf_len);
951 			if (IS_ERR(start)) {
952 				ret = PTR_ERR(start);
953 				goto out;
954 			}
955 			if (start < p->buf) {
956 				/* overflow , try again with larger buffer */
957 				ret = fs_path_ensure_buf(p,
958 						p->buf_len + p->buf - start);
959 				if (ret < 0)
960 					goto out;
961 				start = btrfs_ref_to_path(root, tmp_path,
962 							  name_len, name_off,
963 							  eb, dir,
964 							  p->buf, p->buf_len);
965 				if (IS_ERR(start)) {
966 					ret = PTR_ERR(start);
967 					goto out;
968 				}
969 				BUG_ON(start < p->buf);
970 			}
971 			p->start = start;
972 		} else {
973 			ret = fs_path_add_from_extent_buffer(p, eb, name_off,
974 							     name_len);
975 			if (ret < 0)
976 				goto out;
977 		}
978 
979 		cur += elem_size + name_len;
980 		ret = iterate(num, dir, index, p, ctx);
981 		if (ret)
982 			goto out;
983 		num++;
984 	}
985 
986 out:
987 	btrfs_free_path(tmp_path);
988 	fs_path_free(p);
989 	return ret;
990 }
991 
992 typedef int (*iterate_dir_item_t)(int num, struct btrfs_key *di_key,
993 				  const char *name, int name_len,
994 				  const char *data, int data_len,
995 				  u8 type, void *ctx);
996 
997 /*
998  * Helper function to iterate the entries in ONE btrfs_dir_item.
999  * The iterate callback may return a non zero value to stop iteration. This can
1000  * be a negative value for error codes or 1 to simply stop it.
1001  *
1002  * path must point to the dir item when called.
1003  */
1004 static int iterate_dir_item(struct btrfs_root *root, struct btrfs_path *path,
1005 			    struct btrfs_key *found_key,
1006 			    iterate_dir_item_t iterate, void *ctx)
1007 {
1008 	int ret = 0;
1009 	struct extent_buffer *eb;
1010 	struct btrfs_item *item;
1011 	struct btrfs_dir_item *di;
1012 	struct btrfs_key di_key;
1013 	char *buf = NULL;
1014 	int buf_len;
1015 	u32 name_len;
1016 	u32 data_len;
1017 	u32 cur;
1018 	u32 len;
1019 	u32 total;
1020 	int slot;
1021 	int num;
1022 	u8 type;
1023 
1024 	/*
1025 	 * Start with a small buffer (1 page). If later we end up needing more
1026 	 * space, which can happen for xattrs on a fs with a leaf size greater
1027 	 * then the page size, attempt to increase the buffer. Typically xattr
1028 	 * values are small.
1029 	 */
1030 	buf_len = PATH_MAX;
1031 	buf = kmalloc(buf_len, GFP_KERNEL);
1032 	if (!buf) {
1033 		ret = -ENOMEM;
1034 		goto out;
1035 	}
1036 
1037 	eb = path->nodes[0];
1038 	slot = path->slots[0];
1039 	item = btrfs_item_nr(slot);
1040 	di = btrfs_item_ptr(eb, slot, struct btrfs_dir_item);
1041 	cur = 0;
1042 	len = 0;
1043 	total = btrfs_item_size(eb, item);
1044 
1045 	num = 0;
1046 	while (cur < total) {
1047 		name_len = btrfs_dir_name_len(eb, di);
1048 		data_len = btrfs_dir_data_len(eb, di);
1049 		type = btrfs_dir_type(eb, di);
1050 		btrfs_dir_item_key_to_cpu(eb, di, &di_key);
1051 
1052 		if (type == BTRFS_FT_XATTR) {
1053 			if (name_len > XATTR_NAME_MAX) {
1054 				ret = -ENAMETOOLONG;
1055 				goto out;
1056 			}
1057 			if (name_len + data_len > BTRFS_MAX_XATTR_SIZE(root)) {
1058 				ret = -E2BIG;
1059 				goto out;
1060 			}
1061 		} else {
1062 			/*
1063 			 * Path too long
1064 			 */
1065 			if (name_len + data_len > PATH_MAX) {
1066 				ret = -ENAMETOOLONG;
1067 				goto out;
1068 			}
1069 		}
1070 
1071 		if (name_len + data_len > buf_len) {
1072 			buf_len = name_len + data_len;
1073 			if (is_vmalloc_addr(buf)) {
1074 				vfree(buf);
1075 				buf = NULL;
1076 			} else {
1077 				char *tmp = krealloc(buf, buf_len,
1078 						GFP_KERNEL | __GFP_NOWARN);
1079 
1080 				if (!tmp)
1081 					kfree(buf);
1082 				buf = tmp;
1083 			}
1084 			if (!buf) {
1085 				buf = vmalloc(buf_len);
1086 				if (!buf) {
1087 					ret = -ENOMEM;
1088 					goto out;
1089 				}
1090 			}
1091 		}
1092 
1093 		read_extent_buffer(eb, buf, (unsigned long)(di + 1),
1094 				name_len + data_len);
1095 
1096 		len = sizeof(*di) + name_len + data_len;
1097 		di = (struct btrfs_dir_item *)((char *)di + len);
1098 		cur += len;
1099 
1100 		ret = iterate(num, &di_key, buf, name_len, buf + name_len,
1101 				data_len, type, ctx);
1102 		if (ret < 0)
1103 			goto out;
1104 		if (ret) {
1105 			ret = 0;
1106 			goto out;
1107 		}
1108 
1109 		num++;
1110 	}
1111 
1112 out:
1113 	kvfree(buf);
1114 	return ret;
1115 }
1116 
1117 static int __copy_first_ref(int num, u64 dir, int index,
1118 			    struct fs_path *p, void *ctx)
1119 {
1120 	int ret;
1121 	struct fs_path *pt = ctx;
1122 
1123 	ret = fs_path_copy(pt, p);
1124 	if (ret < 0)
1125 		return ret;
1126 
1127 	/* we want the first only */
1128 	return 1;
1129 }
1130 
1131 /*
1132  * Retrieve the first path of an inode. If an inode has more then one
1133  * ref/hardlink, this is ignored.
1134  */
1135 static int get_inode_path(struct btrfs_root *root,
1136 			  u64 ino, struct fs_path *path)
1137 {
1138 	int ret;
1139 	struct btrfs_key key, found_key;
1140 	struct btrfs_path *p;
1141 
1142 	p = alloc_path_for_send();
1143 	if (!p)
1144 		return -ENOMEM;
1145 
1146 	fs_path_reset(path);
1147 
1148 	key.objectid = ino;
1149 	key.type = BTRFS_INODE_REF_KEY;
1150 	key.offset = 0;
1151 
1152 	ret = btrfs_search_slot_for_read(root, &key, p, 1, 0);
1153 	if (ret < 0)
1154 		goto out;
1155 	if (ret) {
1156 		ret = 1;
1157 		goto out;
1158 	}
1159 	btrfs_item_key_to_cpu(p->nodes[0], &found_key, p->slots[0]);
1160 	if (found_key.objectid != ino ||
1161 	    (found_key.type != BTRFS_INODE_REF_KEY &&
1162 	     found_key.type != BTRFS_INODE_EXTREF_KEY)) {
1163 		ret = -ENOENT;
1164 		goto out;
1165 	}
1166 
1167 	ret = iterate_inode_ref(root, p, &found_key, 1,
1168 				__copy_first_ref, path);
1169 	if (ret < 0)
1170 		goto out;
1171 	ret = 0;
1172 
1173 out:
1174 	btrfs_free_path(p);
1175 	return ret;
1176 }
1177 
1178 struct backref_ctx {
1179 	struct send_ctx *sctx;
1180 
1181 	struct btrfs_path *path;
1182 	/* number of total found references */
1183 	u64 found;
1184 
1185 	/*
1186 	 * used for clones found in send_root. clones found behind cur_objectid
1187 	 * and cur_offset are not considered as allowed clones.
1188 	 */
1189 	u64 cur_objectid;
1190 	u64 cur_offset;
1191 
1192 	/* may be truncated in case it's the last extent in a file */
1193 	u64 extent_len;
1194 
1195 	/* data offset in the file extent item */
1196 	u64 data_offset;
1197 
1198 	/* Just to check for bugs in backref resolving */
1199 	int found_itself;
1200 };
1201 
1202 static int __clone_root_cmp_bsearch(const void *key, const void *elt)
1203 {
1204 	u64 root = (u64)(uintptr_t)key;
1205 	struct clone_root *cr = (struct clone_root *)elt;
1206 
1207 	if (root < cr->root->objectid)
1208 		return -1;
1209 	if (root > cr->root->objectid)
1210 		return 1;
1211 	return 0;
1212 }
1213 
1214 static int __clone_root_cmp_sort(const void *e1, const void *e2)
1215 {
1216 	struct clone_root *cr1 = (struct clone_root *)e1;
1217 	struct clone_root *cr2 = (struct clone_root *)e2;
1218 
1219 	if (cr1->root->objectid < cr2->root->objectid)
1220 		return -1;
1221 	if (cr1->root->objectid > cr2->root->objectid)
1222 		return 1;
1223 	return 0;
1224 }
1225 
1226 /*
1227  * Called for every backref that is found for the current extent.
1228  * Results are collected in sctx->clone_roots->ino/offset/found_refs
1229  */
1230 static int __iterate_backrefs(u64 ino, u64 offset, u64 root, void *ctx_)
1231 {
1232 	struct backref_ctx *bctx = ctx_;
1233 	struct clone_root *found;
1234 	int ret;
1235 	u64 i_size;
1236 
1237 	/* First check if the root is in the list of accepted clone sources */
1238 	found = bsearch((void *)(uintptr_t)root, bctx->sctx->clone_roots,
1239 			bctx->sctx->clone_roots_cnt,
1240 			sizeof(struct clone_root),
1241 			__clone_root_cmp_bsearch);
1242 	if (!found)
1243 		return 0;
1244 
1245 	if (found->root == bctx->sctx->send_root &&
1246 	    ino == bctx->cur_objectid &&
1247 	    offset == bctx->cur_offset) {
1248 		bctx->found_itself = 1;
1249 	}
1250 
1251 	/*
1252 	 * There are inodes that have extents that lie behind its i_size. Don't
1253 	 * accept clones from these extents.
1254 	 */
1255 	ret = __get_inode_info(found->root, bctx->path, ino, &i_size, NULL, NULL,
1256 			       NULL, NULL, NULL);
1257 	btrfs_release_path(bctx->path);
1258 	if (ret < 0)
1259 		return ret;
1260 
1261 	if (offset + bctx->data_offset + bctx->extent_len > i_size)
1262 		return 0;
1263 
1264 	/*
1265 	 * Make sure we don't consider clones from send_root that are
1266 	 * behind the current inode/offset.
1267 	 */
1268 	if (found->root == bctx->sctx->send_root) {
1269 		/*
1270 		 * TODO for the moment we don't accept clones from the inode
1271 		 * that is currently send. We may change this when
1272 		 * BTRFS_IOC_CLONE_RANGE supports cloning from and to the same
1273 		 * file.
1274 		 */
1275 		if (ino >= bctx->cur_objectid)
1276 			return 0;
1277 #if 0
1278 		if (ino > bctx->cur_objectid)
1279 			return 0;
1280 		if (offset + bctx->extent_len > bctx->cur_offset)
1281 			return 0;
1282 #endif
1283 	}
1284 
1285 	bctx->found++;
1286 	found->found_refs++;
1287 	if (ino < found->ino) {
1288 		found->ino = ino;
1289 		found->offset = offset;
1290 	} else if (found->ino == ino) {
1291 		/*
1292 		 * same extent found more then once in the same file.
1293 		 */
1294 		if (found->offset > offset + bctx->extent_len)
1295 			found->offset = offset;
1296 	}
1297 
1298 	return 0;
1299 }
1300 
1301 /*
1302  * Given an inode, offset and extent item, it finds a good clone for a clone
1303  * instruction. Returns -ENOENT when none could be found. The function makes
1304  * sure that the returned clone is usable at the point where sending is at the
1305  * moment. This means, that no clones are accepted which lie behind the current
1306  * inode+offset.
1307  *
1308  * path must point to the extent item when called.
1309  */
1310 static int find_extent_clone(struct send_ctx *sctx,
1311 			     struct btrfs_path *path,
1312 			     u64 ino, u64 data_offset,
1313 			     u64 ino_size,
1314 			     struct clone_root **found)
1315 {
1316 	struct btrfs_fs_info *fs_info = sctx->send_root->fs_info;
1317 	int ret;
1318 	int extent_type;
1319 	u64 logical;
1320 	u64 disk_byte;
1321 	u64 num_bytes;
1322 	u64 extent_item_pos;
1323 	u64 flags = 0;
1324 	struct btrfs_file_extent_item *fi;
1325 	struct extent_buffer *eb = path->nodes[0];
1326 	struct backref_ctx *backref_ctx = NULL;
1327 	struct clone_root *cur_clone_root;
1328 	struct btrfs_key found_key;
1329 	struct btrfs_path *tmp_path;
1330 	int compressed;
1331 	u32 i;
1332 
1333 	tmp_path = alloc_path_for_send();
1334 	if (!tmp_path)
1335 		return -ENOMEM;
1336 
1337 	/* We only use this path under the commit sem */
1338 	tmp_path->need_commit_sem = 0;
1339 
1340 	backref_ctx = kmalloc(sizeof(*backref_ctx), GFP_KERNEL);
1341 	if (!backref_ctx) {
1342 		ret = -ENOMEM;
1343 		goto out;
1344 	}
1345 
1346 	backref_ctx->path = tmp_path;
1347 
1348 	if (data_offset >= ino_size) {
1349 		/*
1350 		 * There may be extents that lie behind the file's size.
1351 		 * I at least had this in combination with snapshotting while
1352 		 * writing large files.
1353 		 */
1354 		ret = 0;
1355 		goto out;
1356 	}
1357 
1358 	fi = btrfs_item_ptr(eb, path->slots[0],
1359 			struct btrfs_file_extent_item);
1360 	extent_type = btrfs_file_extent_type(eb, fi);
1361 	if (extent_type == BTRFS_FILE_EXTENT_INLINE) {
1362 		ret = -ENOENT;
1363 		goto out;
1364 	}
1365 	compressed = btrfs_file_extent_compression(eb, fi);
1366 
1367 	num_bytes = btrfs_file_extent_num_bytes(eb, fi);
1368 	disk_byte = btrfs_file_extent_disk_bytenr(eb, fi);
1369 	if (disk_byte == 0) {
1370 		ret = -ENOENT;
1371 		goto out;
1372 	}
1373 	logical = disk_byte + btrfs_file_extent_offset(eb, fi);
1374 
1375 	down_read(&fs_info->commit_root_sem);
1376 	ret = extent_from_logical(fs_info, disk_byte, tmp_path,
1377 				  &found_key, &flags);
1378 	up_read(&fs_info->commit_root_sem);
1379 	btrfs_release_path(tmp_path);
1380 
1381 	if (ret < 0)
1382 		goto out;
1383 	if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
1384 		ret = -EIO;
1385 		goto out;
1386 	}
1387 
1388 	/*
1389 	 * Setup the clone roots.
1390 	 */
1391 	for (i = 0; i < sctx->clone_roots_cnt; i++) {
1392 		cur_clone_root = sctx->clone_roots + i;
1393 		cur_clone_root->ino = (u64)-1;
1394 		cur_clone_root->offset = 0;
1395 		cur_clone_root->found_refs = 0;
1396 	}
1397 
1398 	backref_ctx->sctx = sctx;
1399 	backref_ctx->found = 0;
1400 	backref_ctx->cur_objectid = ino;
1401 	backref_ctx->cur_offset = data_offset;
1402 	backref_ctx->found_itself = 0;
1403 	backref_ctx->extent_len = num_bytes;
1404 	/*
1405 	 * For non-compressed extents iterate_extent_inodes() gives us extent
1406 	 * offsets that already take into account the data offset, but not for
1407 	 * compressed extents, since the offset is logical and not relative to
1408 	 * the physical extent locations. We must take this into account to
1409 	 * avoid sending clone offsets that go beyond the source file's size,
1410 	 * which would result in the clone ioctl failing with -EINVAL on the
1411 	 * receiving end.
1412 	 */
1413 	if (compressed == BTRFS_COMPRESS_NONE)
1414 		backref_ctx->data_offset = 0;
1415 	else
1416 		backref_ctx->data_offset = btrfs_file_extent_offset(eb, fi);
1417 
1418 	/*
1419 	 * The last extent of a file may be too large due to page alignment.
1420 	 * We need to adjust extent_len in this case so that the checks in
1421 	 * __iterate_backrefs work.
1422 	 */
1423 	if (data_offset + num_bytes >= ino_size)
1424 		backref_ctx->extent_len = ino_size - data_offset;
1425 
1426 	/*
1427 	 * Now collect all backrefs.
1428 	 */
1429 	if (compressed == BTRFS_COMPRESS_NONE)
1430 		extent_item_pos = logical - found_key.objectid;
1431 	else
1432 		extent_item_pos = 0;
1433 	ret = iterate_extent_inodes(fs_info,
1434 					found_key.objectid, extent_item_pos, 1,
1435 					__iterate_backrefs, backref_ctx);
1436 
1437 	if (ret < 0)
1438 		goto out;
1439 
1440 	if (!backref_ctx->found_itself) {
1441 		/* found a bug in backref code? */
1442 		ret = -EIO;
1443 		btrfs_err(fs_info,
1444 			  "did not find backref in send_root. inode=%llu, offset=%llu, disk_byte=%llu found extent=%llu",
1445 			  ino, data_offset, disk_byte, found_key.objectid);
1446 		goto out;
1447 	}
1448 
1449 	btrfs_debug(fs_info,
1450 		    "find_extent_clone: data_offset=%llu, ino=%llu, num_bytes=%llu, logical=%llu",
1451 		    data_offset, ino, num_bytes, logical);
1452 
1453 	if (!backref_ctx->found)
1454 		btrfs_debug(fs_info, "no clones found");
1455 
1456 	cur_clone_root = NULL;
1457 	for (i = 0; i < sctx->clone_roots_cnt; i++) {
1458 		if (sctx->clone_roots[i].found_refs) {
1459 			if (!cur_clone_root)
1460 				cur_clone_root = sctx->clone_roots + i;
1461 			else if (sctx->clone_roots[i].root == sctx->send_root)
1462 				/* prefer clones from send_root over others */
1463 				cur_clone_root = sctx->clone_roots + i;
1464 		}
1465 
1466 	}
1467 
1468 	if (cur_clone_root) {
1469 		*found = cur_clone_root;
1470 		ret = 0;
1471 	} else {
1472 		ret = -ENOENT;
1473 	}
1474 
1475 out:
1476 	btrfs_free_path(tmp_path);
1477 	kfree(backref_ctx);
1478 	return ret;
1479 }
1480 
1481 static int read_symlink(struct btrfs_root *root,
1482 			u64 ino,
1483 			struct fs_path *dest)
1484 {
1485 	int ret;
1486 	struct btrfs_path *path;
1487 	struct btrfs_key key;
1488 	struct btrfs_file_extent_item *ei;
1489 	u8 type;
1490 	u8 compression;
1491 	unsigned long off;
1492 	int len;
1493 
1494 	path = alloc_path_for_send();
1495 	if (!path)
1496 		return -ENOMEM;
1497 
1498 	key.objectid = ino;
1499 	key.type = BTRFS_EXTENT_DATA_KEY;
1500 	key.offset = 0;
1501 	ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
1502 	if (ret < 0)
1503 		goto out;
1504 	if (ret) {
1505 		/*
1506 		 * An empty symlink inode. Can happen in rare error paths when
1507 		 * creating a symlink (transaction committed before the inode
1508 		 * eviction handler removed the symlink inode items and a crash
1509 		 * happened in between or the subvol was snapshoted in between).
1510 		 * Print an informative message to dmesg/syslog so that the user
1511 		 * can delete the symlink.
1512 		 */
1513 		btrfs_err(root->fs_info,
1514 			  "Found empty symlink inode %llu at root %llu",
1515 			  ino, root->root_key.objectid);
1516 		ret = -EIO;
1517 		goto out;
1518 	}
1519 
1520 	ei = btrfs_item_ptr(path->nodes[0], path->slots[0],
1521 			struct btrfs_file_extent_item);
1522 	type = btrfs_file_extent_type(path->nodes[0], ei);
1523 	compression = btrfs_file_extent_compression(path->nodes[0], ei);
1524 	BUG_ON(type != BTRFS_FILE_EXTENT_INLINE);
1525 	BUG_ON(compression);
1526 
1527 	off = btrfs_file_extent_inline_start(ei);
1528 	len = btrfs_file_extent_inline_len(path->nodes[0], path->slots[0], ei);
1529 
1530 	ret = fs_path_add_from_extent_buffer(dest, path->nodes[0], off, len);
1531 
1532 out:
1533 	btrfs_free_path(path);
1534 	return ret;
1535 }
1536 
1537 /*
1538  * Helper function to generate a file name that is unique in the root of
1539  * send_root and parent_root. This is used to generate names for orphan inodes.
1540  */
1541 static int gen_unique_name(struct send_ctx *sctx,
1542 			   u64 ino, u64 gen,
1543 			   struct fs_path *dest)
1544 {
1545 	int ret = 0;
1546 	struct btrfs_path *path;
1547 	struct btrfs_dir_item *di;
1548 	char tmp[64];
1549 	int len;
1550 	u64 idx = 0;
1551 
1552 	path = alloc_path_for_send();
1553 	if (!path)
1554 		return -ENOMEM;
1555 
1556 	while (1) {
1557 		len = snprintf(tmp, sizeof(tmp), "o%llu-%llu-%llu",
1558 				ino, gen, idx);
1559 		ASSERT(len < sizeof(tmp));
1560 
1561 		di = btrfs_lookup_dir_item(NULL, sctx->send_root,
1562 				path, BTRFS_FIRST_FREE_OBJECTID,
1563 				tmp, strlen(tmp), 0);
1564 		btrfs_release_path(path);
1565 		if (IS_ERR(di)) {
1566 			ret = PTR_ERR(di);
1567 			goto out;
1568 		}
1569 		if (di) {
1570 			/* not unique, try again */
1571 			idx++;
1572 			continue;
1573 		}
1574 
1575 		if (!sctx->parent_root) {
1576 			/* unique */
1577 			ret = 0;
1578 			break;
1579 		}
1580 
1581 		di = btrfs_lookup_dir_item(NULL, sctx->parent_root,
1582 				path, BTRFS_FIRST_FREE_OBJECTID,
1583 				tmp, strlen(tmp), 0);
1584 		btrfs_release_path(path);
1585 		if (IS_ERR(di)) {
1586 			ret = PTR_ERR(di);
1587 			goto out;
1588 		}
1589 		if (di) {
1590 			/* not unique, try again */
1591 			idx++;
1592 			continue;
1593 		}
1594 		/* unique */
1595 		break;
1596 	}
1597 
1598 	ret = fs_path_add(dest, tmp, strlen(tmp));
1599 
1600 out:
1601 	btrfs_free_path(path);
1602 	return ret;
1603 }
1604 
1605 enum inode_state {
1606 	inode_state_no_change,
1607 	inode_state_will_create,
1608 	inode_state_did_create,
1609 	inode_state_will_delete,
1610 	inode_state_did_delete,
1611 };
1612 
1613 static int get_cur_inode_state(struct send_ctx *sctx, u64 ino, u64 gen)
1614 {
1615 	int ret;
1616 	int left_ret;
1617 	int right_ret;
1618 	u64 left_gen;
1619 	u64 right_gen;
1620 
1621 	ret = get_inode_info(sctx->send_root, ino, NULL, &left_gen, NULL, NULL,
1622 			NULL, NULL);
1623 	if (ret < 0 && ret != -ENOENT)
1624 		goto out;
1625 	left_ret = ret;
1626 
1627 	if (!sctx->parent_root) {
1628 		right_ret = -ENOENT;
1629 	} else {
1630 		ret = get_inode_info(sctx->parent_root, ino, NULL, &right_gen,
1631 				NULL, NULL, NULL, NULL);
1632 		if (ret < 0 && ret != -ENOENT)
1633 			goto out;
1634 		right_ret = ret;
1635 	}
1636 
1637 	if (!left_ret && !right_ret) {
1638 		if (left_gen == gen && right_gen == gen) {
1639 			ret = inode_state_no_change;
1640 		} else if (left_gen == gen) {
1641 			if (ino < sctx->send_progress)
1642 				ret = inode_state_did_create;
1643 			else
1644 				ret = inode_state_will_create;
1645 		} else if (right_gen == gen) {
1646 			if (ino < sctx->send_progress)
1647 				ret = inode_state_did_delete;
1648 			else
1649 				ret = inode_state_will_delete;
1650 		} else  {
1651 			ret = -ENOENT;
1652 		}
1653 	} else if (!left_ret) {
1654 		if (left_gen == gen) {
1655 			if (ino < sctx->send_progress)
1656 				ret = inode_state_did_create;
1657 			else
1658 				ret = inode_state_will_create;
1659 		} else {
1660 			ret = -ENOENT;
1661 		}
1662 	} else if (!right_ret) {
1663 		if (right_gen == gen) {
1664 			if (ino < sctx->send_progress)
1665 				ret = inode_state_did_delete;
1666 			else
1667 				ret = inode_state_will_delete;
1668 		} else {
1669 			ret = -ENOENT;
1670 		}
1671 	} else {
1672 		ret = -ENOENT;
1673 	}
1674 
1675 out:
1676 	return ret;
1677 }
1678 
1679 static int is_inode_existent(struct send_ctx *sctx, u64 ino, u64 gen)
1680 {
1681 	int ret;
1682 
1683 	ret = get_cur_inode_state(sctx, ino, gen);
1684 	if (ret < 0)
1685 		goto out;
1686 
1687 	if (ret == inode_state_no_change ||
1688 	    ret == inode_state_did_create ||
1689 	    ret == inode_state_will_delete)
1690 		ret = 1;
1691 	else
1692 		ret = 0;
1693 
1694 out:
1695 	return ret;
1696 }
1697 
1698 /*
1699  * Helper function to lookup a dir item in a dir.
1700  */
1701 static int lookup_dir_item_inode(struct btrfs_root *root,
1702 				 u64 dir, const char *name, int name_len,
1703 				 u64 *found_inode,
1704 				 u8 *found_type)
1705 {
1706 	int ret = 0;
1707 	struct btrfs_dir_item *di;
1708 	struct btrfs_key key;
1709 	struct btrfs_path *path;
1710 
1711 	path = alloc_path_for_send();
1712 	if (!path)
1713 		return -ENOMEM;
1714 
1715 	di = btrfs_lookup_dir_item(NULL, root, path,
1716 			dir, name, name_len, 0);
1717 	if (!di) {
1718 		ret = -ENOENT;
1719 		goto out;
1720 	}
1721 	if (IS_ERR(di)) {
1722 		ret = PTR_ERR(di);
1723 		goto out;
1724 	}
1725 	btrfs_dir_item_key_to_cpu(path->nodes[0], di, &key);
1726 	if (key.type == BTRFS_ROOT_ITEM_KEY) {
1727 		ret = -ENOENT;
1728 		goto out;
1729 	}
1730 	*found_inode = key.objectid;
1731 	*found_type = btrfs_dir_type(path->nodes[0], di);
1732 
1733 out:
1734 	btrfs_free_path(path);
1735 	return ret;
1736 }
1737 
1738 /*
1739  * Looks up the first btrfs_inode_ref of a given ino. It returns the parent dir,
1740  * generation of the parent dir and the name of the dir entry.
1741  */
1742 static int get_first_ref(struct btrfs_root *root, u64 ino,
1743 			 u64 *dir, u64 *dir_gen, struct fs_path *name)
1744 {
1745 	int ret;
1746 	struct btrfs_key key;
1747 	struct btrfs_key found_key;
1748 	struct btrfs_path *path;
1749 	int len;
1750 	u64 parent_dir;
1751 
1752 	path = alloc_path_for_send();
1753 	if (!path)
1754 		return -ENOMEM;
1755 
1756 	key.objectid = ino;
1757 	key.type = BTRFS_INODE_REF_KEY;
1758 	key.offset = 0;
1759 
1760 	ret = btrfs_search_slot_for_read(root, &key, path, 1, 0);
1761 	if (ret < 0)
1762 		goto out;
1763 	if (!ret)
1764 		btrfs_item_key_to_cpu(path->nodes[0], &found_key,
1765 				path->slots[0]);
1766 	if (ret || found_key.objectid != ino ||
1767 	    (found_key.type != BTRFS_INODE_REF_KEY &&
1768 	     found_key.type != BTRFS_INODE_EXTREF_KEY)) {
1769 		ret = -ENOENT;
1770 		goto out;
1771 	}
1772 
1773 	if (found_key.type == BTRFS_INODE_REF_KEY) {
1774 		struct btrfs_inode_ref *iref;
1775 		iref = btrfs_item_ptr(path->nodes[0], path->slots[0],
1776 				      struct btrfs_inode_ref);
1777 		len = btrfs_inode_ref_name_len(path->nodes[0], iref);
1778 		ret = fs_path_add_from_extent_buffer(name, path->nodes[0],
1779 						     (unsigned long)(iref + 1),
1780 						     len);
1781 		parent_dir = found_key.offset;
1782 	} else {
1783 		struct btrfs_inode_extref *extref;
1784 		extref = btrfs_item_ptr(path->nodes[0], path->slots[0],
1785 					struct btrfs_inode_extref);
1786 		len = btrfs_inode_extref_name_len(path->nodes[0], extref);
1787 		ret = fs_path_add_from_extent_buffer(name, path->nodes[0],
1788 					(unsigned long)&extref->name, len);
1789 		parent_dir = btrfs_inode_extref_parent(path->nodes[0], extref);
1790 	}
1791 	if (ret < 0)
1792 		goto out;
1793 	btrfs_release_path(path);
1794 
1795 	if (dir_gen) {
1796 		ret = get_inode_info(root, parent_dir, NULL, dir_gen, NULL,
1797 				     NULL, NULL, NULL);
1798 		if (ret < 0)
1799 			goto out;
1800 	}
1801 
1802 	*dir = parent_dir;
1803 
1804 out:
1805 	btrfs_free_path(path);
1806 	return ret;
1807 }
1808 
1809 static int is_first_ref(struct btrfs_root *root,
1810 			u64 ino, u64 dir,
1811 			const char *name, int name_len)
1812 {
1813 	int ret;
1814 	struct fs_path *tmp_name;
1815 	u64 tmp_dir;
1816 
1817 	tmp_name = fs_path_alloc();
1818 	if (!tmp_name)
1819 		return -ENOMEM;
1820 
1821 	ret = get_first_ref(root, ino, &tmp_dir, NULL, tmp_name);
1822 	if (ret < 0)
1823 		goto out;
1824 
1825 	if (dir != tmp_dir || name_len != fs_path_len(tmp_name)) {
1826 		ret = 0;
1827 		goto out;
1828 	}
1829 
1830 	ret = !memcmp(tmp_name->start, name, name_len);
1831 
1832 out:
1833 	fs_path_free(tmp_name);
1834 	return ret;
1835 }
1836 
1837 /*
1838  * Used by process_recorded_refs to determine if a new ref would overwrite an
1839  * already existing ref. In case it detects an overwrite, it returns the
1840  * inode/gen in who_ino/who_gen.
1841  * When an overwrite is detected, process_recorded_refs does proper orphanizing
1842  * to make sure later references to the overwritten inode are possible.
1843  * Orphanizing is however only required for the first ref of an inode.
1844  * process_recorded_refs does an additional is_first_ref check to see if
1845  * orphanizing is really required.
1846  */
1847 static int will_overwrite_ref(struct send_ctx *sctx, u64 dir, u64 dir_gen,
1848 			      const char *name, int name_len,
1849 			      u64 *who_ino, u64 *who_gen)
1850 {
1851 	int ret = 0;
1852 	u64 gen;
1853 	u64 other_inode = 0;
1854 	u8 other_type = 0;
1855 
1856 	if (!sctx->parent_root)
1857 		goto out;
1858 
1859 	ret = is_inode_existent(sctx, dir, dir_gen);
1860 	if (ret <= 0)
1861 		goto out;
1862 
1863 	/*
1864 	 * If we have a parent root we need to verify that the parent dir was
1865 	 * not deleted and then re-created, if it was then we have no overwrite
1866 	 * and we can just unlink this entry.
1867 	 */
1868 	if (sctx->parent_root) {
1869 		ret = get_inode_info(sctx->parent_root, dir, NULL, &gen, NULL,
1870 				     NULL, NULL, NULL);
1871 		if (ret < 0 && ret != -ENOENT)
1872 			goto out;
1873 		if (ret) {
1874 			ret = 0;
1875 			goto out;
1876 		}
1877 		if (gen != dir_gen)
1878 			goto out;
1879 	}
1880 
1881 	ret = lookup_dir_item_inode(sctx->parent_root, dir, name, name_len,
1882 			&other_inode, &other_type);
1883 	if (ret < 0 && ret != -ENOENT)
1884 		goto out;
1885 	if (ret) {
1886 		ret = 0;
1887 		goto out;
1888 	}
1889 
1890 	/*
1891 	 * Check if the overwritten ref was already processed. If yes, the ref
1892 	 * was already unlinked/moved, so we can safely assume that we will not
1893 	 * overwrite anything at this point in time.
1894 	 */
1895 	if (other_inode > sctx->send_progress ||
1896 	    is_waiting_for_move(sctx, other_inode)) {
1897 		ret = get_inode_info(sctx->parent_root, other_inode, NULL,
1898 				who_gen, NULL, NULL, NULL, NULL);
1899 		if (ret < 0)
1900 			goto out;
1901 
1902 		ret = 1;
1903 		*who_ino = other_inode;
1904 	} else {
1905 		ret = 0;
1906 	}
1907 
1908 out:
1909 	return ret;
1910 }
1911 
1912 /*
1913  * Checks if the ref was overwritten by an already processed inode. This is
1914  * used by __get_cur_name_and_parent to find out if the ref was orphanized and
1915  * thus the orphan name needs be used.
1916  * process_recorded_refs also uses it to avoid unlinking of refs that were
1917  * overwritten.
1918  */
1919 static int did_overwrite_ref(struct send_ctx *sctx,
1920 			    u64 dir, u64 dir_gen,
1921 			    u64 ino, u64 ino_gen,
1922 			    const char *name, int name_len)
1923 {
1924 	int ret = 0;
1925 	u64 gen;
1926 	u64 ow_inode;
1927 	u8 other_type;
1928 
1929 	if (!sctx->parent_root)
1930 		goto out;
1931 
1932 	ret = is_inode_existent(sctx, dir, dir_gen);
1933 	if (ret <= 0)
1934 		goto out;
1935 
1936 	/* check if the ref was overwritten by another ref */
1937 	ret = lookup_dir_item_inode(sctx->send_root, dir, name, name_len,
1938 			&ow_inode, &other_type);
1939 	if (ret < 0 && ret != -ENOENT)
1940 		goto out;
1941 	if (ret) {
1942 		/* was never and will never be overwritten */
1943 		ret = 0;
1944 		goto out;
1945 	}
1946 
1947 	ret = get_inode_info(sctx->send_root, ow_inode, NULL, &gen, NULL, NULL,
1948 			NULL, NULL);
1949 	if (ret < 0)
1950 		goto out;
1951 
1952 	if (ow_inode == ino && gen == ino_gen) {
1953 		ret = 0;
1954 		goto out;
1955 	}
1956 
1957 	/*
1958 	 * We know that it is or will be overwritten. Check this now.
1959 	 * The current inode being processed might have been the one that caused
1960 	 * inode 'ino' to be orphanized, therefore check if ow_inode matches
1961 	 * the current inode being processed.
1962 	 */
1963 	if ((ow_inode < sctx->send_progress) ||
1964 	    (ino != sctx->cur_ino && ow_inode == sctx->cur_ino &&
1965 	     gen == sctx->cur_inode_gen))
1966 		ret = 1;
1967 	else
1968 		ret = 0;
1969 
1970 out:
1971 	return ret;
1972 }
1973 
1974 /*
1975  * Same as did_overwrite_ref, but also checks if it is the first ref of an inode
1976  * that got overwritten. This is used by process_recorded_refs to determine
1977  * if it has to use the path as returned by get_cur_path or the orphan name.
1978  */
1979 static int did_overwrite_first_ref(struct send_ctx *sctx, u64 ino, u64 gen)
1980 {
1981 	int ret = 0;
1982 	struct fs_path *name = NULL;
1983 	u64 dir;
1984 	u64 dir_gen;
1985 
1986 	if (!sctx->parent_root)
1987 		goto out;
1988 
1989 	name = fs_path_alloc();
1990 	if (!name)
1991 		return -ENOMEM;
1992 
1993 	ret = get_first_ref(sctx->parent_root, ino, &dir, &dir_gen, name);
1994 	if (ret < 0)
1995 		goto out;
1996 
1997 	ret = did_overwrite_ref(sctx, dir, dir_gen, ino, gen,
1998 			name->start, fs_path_len(name));
1999 
2000 out:
2001 	fs_path_free(name);
2002 	return ret;
2003 }
2004 
2005 /*
2006  * Insert a name cache entry. On 32bit kernels the radix tree index is 32bit,
2007  * so we need to do some special handling in case we have clashes. This function
2008  * takes care of this with the help of name_cache_entry::radix_list.
2009  * In case of error, nce is kfreed.
2010  */
2011 static int name_cache_insert(struct send_ctx *sctx,
2012 			     struct name_cache_entry *nce)
2013 {
2014 	int ret = 0;
2015 	struct list_head *nce_head;
2016 
2017 	nce_head = radix_tree_lookup(&sctx->name_cache,
2018 			(unsigned long)nce->ino);
2019 	if (!nce_head) {
2020 		nce_head = kmalloc(sizeof(*nce_head), GFP_KERNEL);
2021 		if (!nce_head) {
2022 			kfree(nce);
2023 			return -ENOMEM;
2024 		}
2025 		INIT_LIST_HEAD(nce_head);
2026 
2027 		ret = radix_tree_insert(&sctx->name_cache, nce->ino, nce_head);
2028 		if (ret < 0) {
2029 			kfree(nce_head);
2030 			kfree(nce);
2031 			return ret;
2032 		}
2033 	}
2034 	list_add_tail(&nce->radix_list, nce_head);
2035 	list_add_tail(&nce->list, &sctx->name_cache_list);
2036 	sctx->name_cache_size++;
2037 
2038 	return ret;
2039 }
2040 
2041 static void name_cache_delete(struct send_ctx *sctx,
2042 			      struct name_cache_entry *nce)
2043 {
2044 	struct list_head *nce_head;
2045 
2046 	nce_head = radix_tree_lookup(&sctx->name_cache,
2047 			(unsigned long)nce->ino);
2048 	if (!nce_head) {
2049 		btrfs_err(sctx->send_root->fs_info,
2050 	      "name_cache_delete lookup failed ino %llu cache size %d, leaking memory",
2051 			nce->ino, sctx->name_cache_size);
2052 	}
2053 
2054 	list_del(&nce->radix_list);
2055 	list_del(&nce->list);
2056 	sctx->name_cache_size--;
2057 
2058 	/*
2059 	 * We may not get to the final release of nce_head if the lookup fails
2060 	 */
2061 	if (nce_head && list_empty(nce_head)) {
2062 		radix_tree_delete(&sctx->name_cache, (unsigned long)nce->ino);
2063 		kfree(nce_head);
2064 	}
2065 }
2066 
2067 static struct name_cache_entry *name_cache_search(struct send_ctx *sctx,
2068 						    u64 ino, u64 gen)
2069 {
2070 	struct list_head *nce_head;
2071 	struct name_cache_entry *cur;
2072 
2073 	nce_head = radix_tree_lookup(&sctx->name_cache, (unsigned long)ino);
2074 	if (!nce_head)
2075 		return NULL;
2076 
2077 	list_for_each_entry(cur, nce_head, radix_list) {
2078 		if (cur->ino == ino && cur->gen == gen)
2079 			return cur;
2080 	}
2081 	return NULL;
2082 }
2083 
2084 /*
2085  * Removes the entry from the list and adds it back to the end. This marks the
2086  * entry as recently used so that name_cache_clean_unused does not remove it.
2087  */
2088 static void name_cache_used(struct send_ctx *sctx, struct name_cache_entry *nce)
2089 {
2090 	list_del(&nce->list);
2091 	list_add_tail(&nce->list, &sctx->name_cache_list);
2092 }
2093 
2094 /*
2095  * Remove some entries from the beginning of name_cache_list.
2096  */
2097 static void name_cache_clean_unused(struct send_ctx *sctx)
2098 {
2099 	struct name_cache_entry *nce;
2100 
2101 	if (sctx->name_cache_size < SEND_CTX_NAME_CACHE_CLEAN_SIZE)
2102 		return;
2103 
2104 	while (sctx->name_cache_size > SEND_CTX_MAX_NAME_CACHE_SIZE) {
2105 		nce = list_entry(sctx->name_cache_list.next,
2106 				struct name_cache_entry, list);
2107 		name_cache_delete(sctx, nce);
2108 		kfree(nce);
2109 	}
2110 }
2111 
2112 static void name_cache_free(struct send_ctx *sctx)
2113 {
2114 	struct name_cache_entry *nce;
2115 
2116 	while (!list_empty(&sctx->name_cache_list)) {
2117 		nce = list_entry(sctx->name_cache_list.next,
2118 				struct name_cache_entry, list);
2119 		name_cache_delete(sctx, nce);
2120 		kfree(nce);
2121 	}
2122 }
2123 
2124 /*
2125  * Used by get_cur_path for each ref up to the root.
2126  * Returns 0 if it succeeded.
2127  * Returns 1 if the inode is not existent or got overwritten. In that case, the
2128  * name is an orphan name. This instructs get_cur_path to stop iterating. If 1
2129  * is returned, parent_ino/parent_gen are not guaranteed to be valid.
2130  * Returns <0 in case of error.
2131  */
2132 static int __get_cur_name_and_parent(struct send_ctx *sctx,
2133 				     u64 ino, u64 gen,
2134 				     u64 *parent_ino,
2135 				     u64 *parent_gen,
2136 				     struct fs_path *dest)
2137 {
2138 	int ret;
2139 	int nce_ret;
2140 	struct name_cache_entry *nce = NULL;
2141 
2142 	/*
2143 	 * First check if we already did a call to this function with the same
2144 	 * ino/gen. If yes, check if the cache entry is still up-to-date. If yes
2145 	 * return the cached result.
2146 	 */
2147 	nce = name_cache_search(sctx, ino, gen);
2148 	if (nce) {
2149 		if (ino < sctx->send_progress && nce->need_later_update) {
2150 			name_cache_delete(sctx, nce);
2151 			kfree(nce);
2152 			nce = NULL;
2153 		} else {
2154 			name_cache_used(sctx, nce);
2155 			*parent_ino = nce->parent_ino;
2156 			*parent_gen = nce->parent_gen;
2157 			ret = fs_path_add(dest, nce->name, nce->name_len);
2158 			if (ret < 0)
2159 				goto out;
2160 			ret = nce->ret;
2161 			goto out;
2162 		}
2163 	}
2164 
2165 	/*
2166 	 * If the inode is not existent yet, add the orphan name and return 1.
2167 	 * This should only happen for the parent dir that we determine in
2168 	 * __record_new_ref
2169 	 */
2170 	ret = is_inode_existent(sctx, ino, gen);
2171 	if (ret < 0)
2172 		goto out;
2173 
2174 	if (!ret) {
2175 		ret = gen_unique_name(sctx, ino, gen, dest);
2176 		if (ret < 0)
2177 			goto out;
2178 		ret = 1;
2179 		goto out_cache;
2180 	}
2181 
2182 	/*
2183 	 * Depending on whether the inode was already processed or not, use
2184 	 * send_root or parent_root for ref lookup.
2185 	 */
2186 	if (ino < sctx->send_progress)
2187 		ret = get_first_ref(sctx->send_root, ino,
2188 				    parent_ino, parent_gen, dest);
2189 	else
2190 		ret = get_first_ref(sctx->parent_root, ino,
2191 				    parent_ino, parent_gen, dest);
2192 	if (ret < 0)
2193 		goto out;
2194 
2195 	/*
2196 	 * Check if the ref was overwritten by an inode's ref that was processed
2197 	 * earlier. If yes, treat as orphan and return 1.
2198 	 */
2199 	ret = did_overwrite_ref(sctx, *parent_ino, *parent_gen, ino, gen,
2200 			dest->start, dest->end - dest->start);
2201 	if (ret < 0)
2202 		goto out;
2203 	if (ret) {
2204 		fs_path_reset(dest);
2205 		ret = gen_unique_name(sctx, ino, gen, dest);
2206 		if (ret < 0)
2207 			goto out;
2208 		ret = 1;
2209 	}
2210 
2211 out_cache:
2212 	/*
2213 	 * Store the result of the lookup in the name cache.
2214 	 */
2215 	nce = kmalloc(sizeof(*nce) + fs_path_len(dest) + 1, GFP_KERNEL);
2216 	if (!nce) {
2217 		ret = -ENOMEM;
2218 		goto out;
2219 	}
2220 
2221 	nce->ino = ino;
2222 	nce->gen = gen;
2223 	nce->parent_ino = *parent_ino;
2224 	nce->parent_gen = *parent_gen;
2225 	nce->name_len = fs_path_len(dest);
2226 	nce->ret = ret;
2227 	strcpy(nce->name, dest->start);
2228 
2229 	if (ino < sctx->send_progress)
2230 		nce->need_later_update = 0;
2231 	else
2232 		nce->need_later_update = 1;
2233 
2234 	nce_ret = name_cache_insert(sctx, nce);
2235 	if (nce_ret < 0)
2236 		ret = nce_ret;
2237 	name_cache_clean_unused(sctx);
2238 
2239 out:
2240 	return ret;
2241 }
2242 
2243 /*
2244  * Magic happens here. This function returns the first ref to an inode as it
2245  * would look like while receiving the stream at this point in time.
2246  * We walk the path up to the root. For every inode in between, we check if it
2247  * was already processed/sent. If yes, we continue with the parent as found
2248  * in send_root. If not, we continue with the parent as found in parent_root.
2249  * If we encounter an inode that was deleted at this point in time, we use the
2250  * inodes "orphan" name instead of the real name and stop. Same with new inodes
2251  * that were not created yet and overwritten inodes/refs.
2252  *
2253  * When do we have have orphan inodes:
2254  * 1. When an inode is freshly created and thus no valid refs are available yet
2255  * 2. When a directory lost all it's refs (deleted) but still has dir items
2256  *    inside which were not processed yet (pending for move/delete). If anyone
2257  *    tried to get the path to the dir items, it would get a path inside that
2258  *    orphan directory.
2259  * 3. When an inode is moved around or gets new links, it may overwrite the ref
2260  *    of an unprocessed inode. If in that case the first ref would be
2261  *    overwritten, the overwritten inode gets "orphanized". Later when we
2262  *    process this overwritten inode, it is restored at a new place by moving
2263  *    the orphan inode.
2264  *
2265  * sctx->send_progress tells this function at which point in time receiving
2266  * would be.
2267  */
2268 static int get_cur_path(struct send_ctx *sctx, u64 ino, u64 gen,
2269 			struct fs_path *dest)
2270 {
2271 	int ret = 0;
2272 	struct fs_path *name = NULL;
2273 	u64 parent_inode = 0;
2274 	u64 parent_gen = 0;
2275 	int stop = 0;
2276 
2277 	name = fs_path_alloc();
2278 	if (!name) {
2279 		ret = -ENOMEM;
2280 		goto out;
2281 	}
2282 
2283 	dest->reversed = 1;
2284 	fs_path_reset(dest);
2285 
2286 	while (!stop && ino != BTRFS_FIRST_FREE_OBJECTID) {
2287 		struct waiting_dir_move *wdm;
2288 
2289 		fs_path_reset(name);
2290 
2291 		if (is_waiting_for_rm(sctx, ino)) {
2292 			ret = gen_unique_name(sctx, ino, gen, name);
2293 			if (ret < 0)
2294 				goto out;
2295 			ret = fs_path_add_path(dest, name);
2296 			break;
2297 		}
2298 
2299 		wdm = get_waiting_dir_move(sctx, ino);
2300 		if (wdm && wdm->orphanized) {
2301 			ret = gen_unique_name(sctx, ino, gen, name);
2302 			stop = 1;
2303 		} else if (wdm) {
2304 			ret = get_first_ref(sctx->parent_root, ino,
2305 					    &parent_inode, &parent_gen, name);
2306 		} else {
2307 			ret = __get_cur_name_and_parent(sctx, ino, gen,
2308 							&parent_inode,
2309 							&parent_gen, name);
2310 			if (ret)
2311 				stop = 1;
2312 		}
2313 
2314 		if (ret < 0)
2315 			goto out;
2316 
2317 		ret = fs_path_add_path(dest, name);
2318 		if (ret < 0)
2319 			goto out;
2320 
2321 		ino = parent_inode;
2322 		gen = parent_gen;
2323 	}
2324 
2325 out:
2326 	fs_path_free(name);
2327 	if (!ret)
2328 		fs_path_unreverse(dest);
2329 	return ret;
2330 }
2331 
2332 /*
2333  * Sends a BTRFS_SEND_C_SUBVOL command/item to userspace
2334  */
2335 static int send_subvol_begin(struct send_ctx *sctx)
2336 {
2337 	int ret;
2338 	struct btrfs_root *send_root = sctx->send_root;
2339 	struct btrfs_root *parent_root = sctx->parent_root;
2340 	struct btrfs_path *path;
2341 	struct btrfs_key key;
2342 	struct btrfs_root_ref *ref;
2343 	struct extent_buffer *leaf;
2344 	char *name = NULL;
2345 	int namelen;
2346 
2347 	path = btrfs_alloc_path();
2348 	if (!path)
2349 		return -ENOMEM;
2350 
2351 	name = kmalloc(BTRFS_PATH_NAME_MAX, GFP_KERNEL);
2352 	if (!name) {
2353 		btrfs_free_path(path);
2354 		return -ENOMEM;
2355 	}
2356 
2357 	key.objectid = send_root->objectid;
2358 	key.type = BTRFS_ROOT_BACKREF_KEY;
2359 	key.offset = 0;
2360 
2361 	ret = btrfs_search_slot_for_read(send_root->fs_info->tree_root,
2362 				&key, path, 1, 0);
2363 	if (ret < 0)
2364 		goto out;
2365 	if (ret) {
2366 		ret = -ENOENT;
2367 		goto out;
2368 	}
2369 
2370 	leaf = path->nodes[0];
2371 	btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
2372 	if (key.type != BTRFS_ROOT_BACKREF_KEY ||
2373 	    key.objectid != send_root->objectid) {
2374 		ret = -ENOENT;
2375 		goto out;
2376 	}
2377 	ref = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_root_ref);
2378 	namelen = btrfs_root_ref_name_len(leaf, ref);
2379 	read_extent_buffer(leaf, name, (unsigned long)(ref + 1), namelen);
2380 	btrfs_release_path(path);
2381 
2382 	if (parent_root) {
2383 		ret = begin_cmd(sctx, BTRFS_SEND_C_SNAPSHOT);
2384 		if (ret < 0)
2385 			goto out;
2386 	} else {
2387 		ret = begin_cmd(sctx, BTRFS_SEND_C_SUBVOL);
2388 		if (ret < 0)
2389 			goto out;
2390 	}
2391 
2392 	TLV_PUT_STRING(sctx, BTRFS_SEND_A_PATH, name, namelen);
2393 
2394 	if (!btrfs_is_empty_uuid(sctx->send_root->root_item.received_uuid))
2395 		TLV_PUT_UUID(sctx, BTRFS_SEND_A_UUID,
2396 			    sctx->send_root->root_item.received_uuid);
2397 	else
2398 		TLV_PUT_UUID(sctx, BTRFS_SEND_A_UUID,
2399 			    sctx->send_root->root_item.uuid);
2400 
2401 	TLV_PUT_U64(sctx, BTRFS_SEND_A_CTRANSID,
2402 		    le64_to_cpu(sctx->send_root->root_item.ctransid));
2403 	if (parent_root) {
2404 		if (!btrfs_is_empty_uuid(parent_root->root_item.received_uuid))
2405 			TLV_PUT_UUID(sctx, BTRFS_SEND_A_CLONE_UUID,
2406 				     parent_root->root_item.received_uuid);
2407 		else
2408 			TLV_PUT_UUID(sctx, BTRFS_SEND_A_CLONE_UUID,
2409 				     parent_root->root_item.uuid);
2410 		TLV_PUT_U64(sctx, BTRFS_SEND_A_CLONE_CTRANSID,
2411 			    le64_to_cpu(sctx->parent_root->root_item.ctransid));
2412 	}
2413 
2414 	ret = send_cmd(sctx);
2415 
2416 tlv_put_failure:
2417 out:
2418 	btrfs_free_path(path);
2419 	kfree(name);
2420 	return ret;
2421 }
2422 
2423 static int send_truncate(struct send_ctx *sctx, u64 ino, u64 gen, u64 size)
2424 {
2425 	struct btrfs_fs_info *fs_info = sctx->send_root->fs_info;
2426 	int ret = 0;
2427 	struct fs_path *p;
2428 
2429 	btrfs_debug(fs_info, "send_truncate %llu size=%llu", ino, size);
2430 
2431 	p = fs_path_alloc();
2432 	if (!p)
2433 		return -ENOMEM;
2434 
2435 	ret = begin_cmd(sctx, BTRFS_SEND_C_TRUNCATE);
2436 	if (ret < 0)
2437 		goto out;
2438 
2439 	ret = get_cur_path(sctx, ino, gen, p);
2440 	if (ret < 0)
2441 		goto out;
2442 	TLV_PUT_PATH(sctx, BTRFS_SEND_A_PATH, p);
2443 	TLV_PUT_U64(sctx, BTRFS_SEND_A_SIZE, size);
2444 
2445 	ret = send_cmd(sctx);
2446 
2447 tlv_put_failure:
2448 out:
2449 	fs_path_free(p);
2450 	return ret;
2451 }
2452 
2453 static int send_chmod(struct send_ctx *sctx, u64 ino, u64 gen, u64 mode)
2454 {
2455 	struct btrfs_fs_info *fs_info = sctx->send_root->fs_info;
2456 	int ret = 0;
2457 	struct fs_path *p;
2458 
2459 	btrfs_debug(fs_info, "send_chmod %llu mode=%llu", ino, mode);
2460 
2461 	p = fs_path_alloc();
2462 	if (!p)
2463 		return -ENOMEM;
2464 
2465 	ret = begin_cmd(sctx, BTRFS_SEND_C_CHMOD);
2466 	if (ret < 0)
2467 		goto out;
2468 
2469 	ret = get_cur_path(sctx, ino, gen, p);
2470 	if (ret < 0)
2471 		goto out;
2472 	TLV_PUT_PATH(sctx, BTRFS_SEND_A_PATH, p);
2473 	TLV_PUT_U64(sctx, BTRFS_SEND_A_MODE, mode & 07777);
2474 
2475 	ret = send_cmd(sctx);
2476 
2477 tlv_put_failure:
2478 out:
2479 	fs_path_free(p);
2480 	return ret;
2481 }
2482 
2483 static int send_chown(struct send_ctx *sctx, u64 ino, u64 gen, u64 uid, u64 gid)
2484 {
2485 	struct btrfs_fs_info *fs_info = sctx->send_root->fs_info;
2486 	int ret = 0;
2487 	struct fs_path *p;
2488 
2489 	btrfs_debug(fs_info, "send_chown %llu uid=%llu, gid=%llu",
2490 		    ino, uid, gid);
2491 
2492 	p = fs_path_alloc();
2493 	if (!p)
2494 		return -ENOMEM;
2495 
2496 	ret = begin_cmd(sctx, BTRFS_SEND_C_CHOWN);
2497 	if (ret < 0)
2498 		goto out;
2499 
2500 	ret = get_cur_path(sctx, ino, gen, p);
2501 	if (ret < 0)
2502 		goto out;
2503 	TLV_PUT_PATH(sctx, BTRFS_SEND_A_PATH, p);
2504 	TLV_PUT_U64(sctx, BTRFS_SEND_A_UID, uid);
2505 	TLV_PUT_U64(sctx, BTRFS_SEND_A_GID, gid);
2506 
2507 	ret = send_cmd(sctx);
2508 
2509 tlv_put_failure:
2510 out:
2511 	fs_path_free(p);
2512 	return ret;
2513 }
2514 
2515 static int send_utimes(struct send_ctx *sctx, u64 ino, u64 gen)
2516 {
2517 	struct btrfs_fs_info *fs_info = sctx->send_root->fs_info;
2518 	int ret = 0;
2519 	struct fs_path *p = NULL;
2520 	struct btrfs_inode_item *ii;
2521 	struct btrfs_path *path = NULL;
2522 	struct extent_buffer *eb;
2523 	struct btrfs_key key;
2524 	int slot;
2525 
2526 	btrfs_debug(fs_info, "send_utimes %llu", ino);
2527 
2528 	p = fs_path_alloc();
2529 	if (!p)
2530 		return -ENOMEM;
2531 
2532 	path = alloc_path_for_send();
2533 	if (!path) {
2534 		ret = -ENOMEM;
2535 		goto out;
2536 	}
2537 
2538 	key.objectid = ino;
2539 	key.type = BTRFS_INODE_ITEM_KEY;
2540 	key.offset = 0;
2541 	ret = btrfs_search_slot(NULL, sctx->send_root, &key, path, 0, 0);
2542 	if (ret > 0)
2543 		ret = -ENOENT;
2544 	if (ret < 0)
2545 		goto out;
2546 
2547 	eb = path->nodes[0];
2548 	slot = path->slots[0];
2549 	ii = btrfs_item_ptr(eb, slot, struct btrfs_inode_item);
2550 
2551 	ret = begin_cmd(sctx, BTRFS_SEND_C_UTIMES);
2552 	if (ret < 0)
2553 		goto out;
2554 
2555 	ret = get_cur_path(sctx, ino, gen, p);
2556 	if (ret < 0)
2557 		goto out;
2558 	TLV_PUT_PATH(sctx, BTRFS_SEND_A_PATH, p);
2559 	TLV_PUT_BTRFS_TIMESPEC(sctx, BTRFS_SEND_A_ATIME, eb, &ii->atime);
2560 	TLV_PUT_BTRFS_TIMESPEC(sctx, BTRFS_SEND_A_MTIME, eb, &ii->mtime);
2561 	TLV_PUT_BTRFS_TIMESPEC(sctx, BTRFS_SEND_A_CTIME, eb, &ii->ctime);
2562 	/* TODO Add otime support when the otime patches get into upstream */
2563 
2564 	ret = send_cmd(sctx);
2565 
2566 tlv_put_failure:
2567 out:
2568 	fs_path_free(p);
2569 	btrfs_free_path(path);
2570 	return ret;
2571 }
2572 
2573 /*
2574  * Sends a BTRFS_SEND_C_MKXXX or SYMLINK command to user space. We don't have
2575  * a valid path yet because we did not process the refs yet. So, the inode
2576  * is created as orphan.
2577  */
2578 static int send_create_inode(struct send_ctx *sctx, u64 ino)
2579 {
2580 	struct btrfs_fs_info *fs_info = sctx->send_root->fs_info;
2581 	int ret = 0;
2582 	struct fs_path *p;
2583 	int cmd;
2584 	u64 gen;
2585 	u64 mode;
2586 	u64 rdev;
2587 
2588 	btrfs_debug(fs_info, "send_create_inode %llu", ino);
2589 
2590 	p = fs_path_alloc();
2591 	if (!p)
2592 		return -ENOMEM;
2593 
2594 	if (ino != sctx->cur_ino) {
2595 		ret = get_inode_info(sctx->send_root, ino, NULL, &gen, &mode,
2596 				     NULL, NULL, &rdev);
2597 		if (ret < 0)
2598 			goto out;
2599 	} else {
2600 		gen = sctx->cur_inode_gen;
2601 		mode = sctx->cur_inode_mode;
2602 		rdev = sctx->cur_inode_rdev;
2603 	}
2604 
2605 	if (S_ISREG(mode)) {
2606 		cmd = BTRFS_SEND_C_MKFILE;
2607 	} else if (S_ISDIR(mode)) {
2608 		cmd = BTRFS_SEND_C_MKDIR;
2609 	} else if (S_ISLNK(mode)) {
2610 		cmd = BTRFS_SEND_C_SYMLINK;
2611 	} else if (S_ISCHR(mode) || S_ISBLK(mode)) {
2612 		cmd = BTRFS_SEND_C_MKNOD;
2613 	} else if (S_ISFIFO(mode)) {
2614 		cmd = BTRFS_SEND_C_MKFIFO;
2615 	} else if (S_ISSOCK(mode)) {
2616 		cmd = BTRFS_SEND_C_MKSOCK;
2617 	} else {
2618 		btrfs_warn(sctx->send_root->fs_info, "unexpected inode type %o",
2619 				(int)(mode & S_IFMT));
2620 		ret = -ENOTSUPP;
2621 		goto out;
2622 	}
2623 
2624 	ret = begin_cmd(sctx, cmd);
2625 	if (ret < 0)
2626 		goto out;
2627 
2628 	ret = gen_unique_name(sctx, ino, gen, p);
2629 	if (ret < 0)
2630 		goto out;
2631 
2632 	TLV_PUT_PATH(sctx, BTRFS_SEND_A_PATH, p);
2633 	TLV_PUT_U64(sctx, BTRFS_SEND_A_INO, ino);
2634 
2635 	if (S_ISLNK(mode)) {
2636 		fs_path_reset(p);
2637 		ret = read_symlink(sctx->send_root, ino, p);
2638 		if (ret < 0)
2639 			goto out;
2640 		TLV_PUT_PATH(sctx, BTRFS_SEND_A_PATH_LINK, p);
2641 	} else if (S_ISCHR(mode) || S_ISBLK(mode) ||
2642 		   S_ISFIFO(mode) || S_ISSOCK(mode)) {
2643 		TLV_PUT_U64(sctx, BTRFS_SEND_A_RDEV, new_encode_dev(rdev));
2644 		TLV_PUT_U64(sctx, BTRFS_SEND_A_MODE, mode);
2645 	}
2646 
2647 	ret = send_cmd(sctx);
2648 	if (ret < 0)
2649 		goto out;
2650 
2651 
2652 tlv_put_failure:
2653 out:
2654 	fs_path_free(p);
2655 	return ret;
2656 }
2657 
2658 /*
2659  * We need some special handling for inodes that get processed before the parent
2660  * directory got created. See process_recorded_refs for details.
2661  * This function does the check if we already created the dir out of order.
2662  */
2663 static int did_create_dir(struct send_ctx *sctx, u64 dir)
2664 {
2665 	int ret = 0;
2666 	struct btrfs_path *path = NULL;
2667 	struct btrfs_key key;
2668 	struct btrfs_key found_key;
2669 	struct btrfs_key di_key;
2670 	struct extent_buffer *eb;
2671 	struct btrfs_dir_item *di;
2672 	int slot;
2673 
2674 	path = alloc_path_for_send();
2675 	if (!path) {
2676 		ret = -ENOMEM;
2677 		goto out;
2678 	}
2679 
2680 	key.objectid = dir;
2681 	key.type = BTRFS_DIR_INDEX_KEY;
2682 	key.offset = 0;
2683 	ret = btrfs_search_slot(NULL, sctx->send_root, &key, path, 0, 0);
2684 	if (ret < 0)
2685 		goto out;
2686 
2687 	while (1) {
2688 		eb = path->nodes[0];
2689 		slot = path->slots[0];
2690 		if (slot >= btrfs_header_nritems(eb)) {
2691 			ret = btrfs_next_leaf(sctx->send_root, path);
2692 			if (ret < 0) {
2693 				goto out;
2694 			} else if (ret > 0) {
2695 				ret = 0;
2696 				break;
2697 			}
2698 			continue;
2699 		}
2700 
2701 		btrfs_item_key_to_cpu(eb, &found_key, slot);
2702 		if (found_key.objectid != key.objectid ||
2703 		    found_key.type != key.type) {
2704 			ret = 0;
2705 			goto out;
2706 		}
2707 
2708 		di = btrfs_item_ptr(eb, slot, struct btrfs_dir_item);
2709 		btrfs_dir_item_key_to_cpu(eb, di, &di_key);
2710 
2711 		if (di_key.type != BTRFS_ROOT_ITEM_KEY &&
2712 		    di_key.objectid < sctx->send_progress) {
2713 			ret = 1;
2714 			goto out;
2715 		}
2716 
2717 		path->slots[0]++;
2718 	}
2719 
2720 out:
2721 	btrfs_free_path(path);
2722 	return ret;
2723 }
2724 
2725 /*
2726  * Only creates the inode if it is:
2727  * 1. Not a directory
2728  * 2. Or a directory which was not created already due to out of order
2729  *    directories. See did_create_dir and process_recorded_refs for details.
2730  */
2731 static int send_create_inode_if_needed(struct send_ctx *sctx)
2732 {
2733 	int ret;
2734 
2735 	if (S_ISDIR(sctx->cur_inode_mode)) {
2736 		ret = did_create_dir(sctx, sctx->cur_ino);
2737 		if (ret < 0)
2738 			goto out;
2739 		if (ret) {
2740 			ret = 0;
2741 			goto out;
2742 		}
2743 	}
2744 
2745 	ret = send_create_inode(sctx, sctx->cur_ino);
2746 	if (ret < 0)
2747 		goto out;
2748 
2749 out:
2750 	return ret;
2751 }
2752 
2753 struct recorded_ref {
2754 	struct list_head list;
2755 	char *dir_path;
2756 	char *name;
2757 	struct fs_path *full_path;
2758 	u64 dir;
2759 	u64 dir_gen;
2760 	int dir_path_len;
2761 	int name_len;
2762 };
2763 
2764 /*
2765  * We need to process new refs before deleted refs, but compare_tree gives us
2766  * everything mixed. So we first record all refs and later process them.
2767  * This function is a helper to record one ref.
2768  */
2769 static int __record_ref(struct list_head *head, u64 dir,
2770 		      u64 dir_gen, struct fs_path *path)
2771 {
2772 	struct recorded_ref *ref;
2773 
2774 	ref = kmalloc(sizeof(*ref), GFP_KERNEL);
2775 	if (!ref)
2776 		return -ENOMEM;
2777 
2778 	ref->dir = dir;
2779 	ref->dir_gen = dir_gen;
2780 	ref->full_path = path;
2781 
2782 	ref->name = (char *)kbasename(ref->full_path->start);
2783 	ref->name_len = ref->full_path->end - ref->name;
2784 	ref->dir_path = ref->full_path->start;
2785 	if (ref->name == ref->full_path->start)
2786 		ref->dir_path_len = 0;
2787 	else
2788 		ref->dir_path_len = ref->full_path->end -
2789 				ref->full_path->start - 1 - ref->name_len;
2790 
2791 	list_add_tail(&ref->list, head);
2792 	return 0;
2793 }
2794 
2795 static int dup_ref(struct recorded_ref *ref, struct list_head *list)
2796 {
2797 	struct recorded_ref *new;
2798 
2799 	new = kmalloc(sizeof(*ref), GFP_KERNEL);
2800 	if (!new)
2801 		return -ENOMEM;
2802 
2803 	new->dir = ref->dir;
2804 	new->dir_gen = ref->dir_gen;
2805 	new->full_path = NULL;
2806 	INIT_LIST_HEAD(&new->list);
2807 	list_add_tail(&new->list, list);
2808 	return 0;
2809 }
2810 
2811 static void __free_recorded_refs(struct list_head *head)
2812 {
2813 	struct recorded_ref *cur;
2814 
2815 	while (!list_empty(head)) {
2816 		cur = list_entry(head->next, struct recorded_ref, list);
2817 		fs_path_free(cur->full_path);
2818 		list_del(&cur->list);
2819 		kfree(cur);
2820 	}
2821 }
2822 
2823 static void free_recorded_refs(struct send_ctx *sctx)
2824 {
2825 	__free_recorded_refs(&sctx->new_refs);
2826 	__free_recorded_refs(&sctx->deleted_refs);
2827 }
2828 
2829 /*
2830  * Renames/moves a file/dir to its orphan name. Used when the first
2831  * ref of an unprocessed inode gets overwritten and for all non empty
2832  * directories.
2833  */
2834 static int orphanize_inode(struct send_ctx *sctx, u64 ino, u64 gen,
2835 			  struct fs_path *path)
2836 {
2837 	int ret;
2838 	struct fs_path *orphan;
2839 
2840 	orphan = fs_path_alloc();
2841 	if (!orphan)
2842 		return -ENOMEM;
2843 
2844 	ret = gen_unique_name(sctx, ino, gen, orphan);
2845 	if (ret < 0)
2846 		goto out;
2847 
2848 	ret = send_rename(sctx, path, orphan);
2849 
2850 out:
2851 	fs_path_free(orphan);
2852 	return ret;
2853 }
2854 
2855 static struct orphan_dir_info *
2856 add_orphan_dir_info(struct send_ctx *sctx, u64 dir_ino)
2857 {
2858 	struct rb_node **p = &sctx->orphan_dirs.rb_node;
2859 	struct rb_node *parent = NULL;
2860 	struct orphan_dir_info *entry, *odi;
2861 
2862 	odi = kmalloc(sizeof(*odi), GFP_KERNEL);
2863 	if (!odi)
2864 		return ERR_PTR(-ENOMEM);
2865 	odi->ino = dir_ino;
2866 	odi->gen = 0;
2867 
2868 	while (*p) {
2869 		parent = *p;
2870 		entry = rb_entry(parent, struct orphan_dir_info, node);
2871 		if (dir_ino < entry->ino) {
2872 			p = &(*p)->rb_left;
2873 		} else if (dir_ino > entry->ino) {
2874 			p = &(*p)->rb_right;
2875 		} else {
2876 			kfree(odi);
2877 			return entry;
2878 		}
2879 	}
2880 
2881 	rb_link_node(&odi->node, parent, p);
2882 	rb_insert_color(&odi->node, &sctx->orphan_dirs);
2883 	return odi;
2884 }
2885 
2886 static struct orphan_dir_info *
2887 get_orphan_dir_info(struct send_ctx *sctx, u64 dir_ino)
2888 {
2889 	struct rb_node *n = sctx->orphan_dirs.rb_node;
2890 	struct orphan_dir_info *entry;
2891 
2892 	while (n) {
2893 		entry = rb_entry(n, struct orphan_dir_info, node);
2894 		if (dir_ino < entry->ino)
2895 			n = n->rb_left;
2896 		else if (dir_ino > entry->ino)
2897 			n = n->rb_right;
2898 		else
2899 			return entry;
2900 	}
2901 	return NULL;
2902 }
2903 
2904 static int is_waiting_for_rm(struct send_ctx *sctx, u64 dir_ino)
2905 {
2906 	struct orphan_dir_info *odi = get_orphan_dir_info(sctx, dir_ino);
2907 
2908 	return odi != NULL;
2909 }
2910 
2911 static void free_orphan_dir_info(struct send_ctx *sctx,
2912 				 struct orphan_dir_info *odi)
2913 {
2914 	if (!odi)
2915 		return;
2916 	rb_erase(&odi->node, &sctx->orphan_dirs);
2917 	kfree(odi);
2918 }
2919 
2920 /*
2921  * Returns 1 if a directory can be removed at this point in time.
2922  * We check this by iterating all dir items and checking if the inode behind
2923  * the dir item was already processed.
2924  */
2925 static int can_rmdir(struct send_ctx *sctx, u64 dir, u64 dir_gen,
2926 		     u64 send_progress)
2927 {
2928 	int ret = 0;
2929 	struct btrfs_root *root = sctx->parent_root;
2930 	struct btrfs_path *path;
2931 	struct btrfs_key key;
2932 	struct btrfs_key found_key;
2933 	struct btrfs_key loc;
2934 	struct btrfs_dir_item *di;
2935 
2936 	/*
2937 	 * Don't try to rmdir the top/root subvolume dir.
2938 	 */
2939 	if (dir == BTRFS_FIRST_FREE_OBJECTID)
2940 		return 0;
2941 
2942 	path = alloc_path_for_send();
2943 	if (!path)
2944 		return -ENOMEM;
2945 
2946 	key.objectid = dir;
2947 	key.type = BTRFS_DIR_INDEX_KEY;
2948 	key.offset = 0;
2949 	ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
2950 	if (ret < 0)
2951 		goto out;
2952 
2953 	while (1) {
2954 		struct waiting_dir_move *dm;
2955 
2956 		if (path->slots[0] >= btrfs_header_nritems(path->nodes[0])) {
2957 			ret = btrfs_next_leaf(root, path);
2958 			if (ret < 0)
2959 				goto out;
2960 			else if (ret > 0)
2961 				break;
2962 			continue;
2963 		}
2964 		btrfs_item_key_to_cpu(path->nodes[0], &found_key,
2965 				      path->slots[0]);
2966 		if (found_key.objectid != key.objectid ||
2967 		    found_key.type != key.type)
2968 			break;
2969 
2970 		di = btrfs_item_ptr(path->nodes[0], path->slots[0],
2971 				struct btrfs_dir_item);
2972 		btrfs_dir_item_key_to_cpu(path->nodes[0], di, &loc);
2973 
2974 		dm = get_waiting_dir_move(sctx, loc.objectid);
2975 		if (dm) {
2976 			struct orphan_dir_info *odi;
2977 
2978 			odi = add_orphan_dir_info(sctx, dir);
2979 			if (IS_ERR(odi)) {
2980 				ret = PTR_ERR(odi);
2981 				goto out;
2982 			}
2983 			odi->gen = dir_gen;
2984 			dm->rmdir_ino = dir;
2985 			ret = 0;
2986 			goto out;
2987 		}
2988 
2989 		if (loc.objectid > send_progress) {
2990 			struct orphan_dir_info *odi;
2991 
2992 			odi = get_orphan_dir_info(sctx, dir);
2993 			free_orphan_dir_info(sctx, odi);
2994 			ret = 0;
2995 			goto out;
2996 		}
2997 
2998 		path->slots[0]++;
2999 	}
3000 
3001 	ret = 1;
3002 
3003 out:
3004 	btrfs_free_path(path);
3005 	return ret;
3006 }
3007 
3008 static int is_waiting_for_move(struct send_ctx *sctx, u64 ino)
3009 {
3010 	struct waiting_dir_move *entry = get_waiting_dir_move(sctx, ino);
3011 
3012 	return entry != NULL;
3013 }
3014 
3015 static int add_waiting_dir_move(struct send_ctx *sctx, u64 ino, bool orphanized)
3016 {
3017 	struct rb_node **p = &sctx->waiting_dir_moves.rb_node;
3018 	struct rb_node *parent = NULL;
3019 	struct waiting_dir_move *entry, *dm;
3020 
3021 	dm = kmalloc(sizeof(*dm), GFP_KERNEL);
3022 	if (!dm)
3023 		return -ENOMEM;
3024 	dm->ino = ino;
3025 	dm->rmdir_ino = 0;
3026 	dm->orphanized = orphanized;
3027 
3028 	while (*p) {
3029 		parent = *p;
3030 		entry = rb_entry(parent, struct waiting_dir_move, node);
3031 		if (ino < entry->ino) {
3032 			p = &(*p)->rb_left;
3033 		} else if (ino > entry->ino) {
3034 			p = &(*p)->rb_right;
3035 		} else {
3036 			kfree(dm);
3037 			return -EEXIST;
3038 		}
3039 	}
3040 
3041 	rb_link_node(&dm->node, parent, p);
3042 	rb_insert_color(&dm->node, &sctx->waiting_dir_moves);
3043 	return 0;
3044 }
3045 
3046 static struct waiting_dir_move *
3047 get_waiting_dir_move(struct send_ctx *sctx, u64 ino)
3048 {
3049 	struct rb_node *n = sctx->waiting_dir_moves.rb_node;
3050 	struct waiting_dir_move *entry;
3051 
3052 	while (n) {
3053 		entry = rb_entry(n, struct waiting_dir_move, node);
3054 		if (ino < entry->ino)
3055 			n = n->rb_left;
3056 		else if (ino > entry->ino)
3057 			n = n->rb_right;
3058 		else
3059 			return entry;
3060 	}
3061 	return NULL;
3062 }
3063 
3064 static void free_waiting_dir_move(struct send_ctx *sctx,
3065 				  struct waiting_dir_move *dm)
3066 {
3067 	if (!dm)
3068 		return;
3069 	rb_erase(&dm->node, &sctx->waiting_dir_moves);
3070 	kfree(dm);
3071 }
3072 
3073 static int add_pending_dir_move(struct send_ctx *sctx,
3074 				u64 ino,
3075 				u64 ino_gen,
3076 				u64 parent_ino,
3077 				struct list_head *new_refs,
3078 				struct list_head *deleted_refs,
3079 				const bool is_orphan)
3080 {
3081 	struct rb_node **p = &sctx->pending_dir_moves.rb_node;
3082 	struct rb_node *parent = NULL;
3083 	struct pending_dir_move *entry = NULL, *pm;
3084 	struct recorded_ref *cur;
3085 	int exists = 0;
3086 	int ret;
3087 
3088 	pm = kmalloc(sizeof(*pm), GFP_KERNEL);
3089 	if (!pm)
3090 		return -ENOMEM;
3091 	pm->parent_ino = parent_ino;
3092 	pm->ino = ino;
3093 	pm->gen = ino_gen;
3094 	INIT_LIST_HEAD(&pm->list);
3095 	INIT_LIST_HEAD(&pm->update_refs);
3096 	RB_CLEAR_NODE(&pm->node);
3097 
3098 	while (*p) {
3099 		parent = *p;
3100 		entry = rb_entry(parent, struct pending_dir_move, node);
3101 		if (parent_ino < entry->parent_ino) {
3102 			p = &(*p)->rb_left;
3103 		} else if (parent_ino > entry->parent_ino) {
3104 			p = &(*p)->rb_right;
3105 		} else {
3106 			exists = 1;
3107 			break;
3108 		}
3109 	}
3110 
3111 	list_for_each_entry(cur, deleted_refs, list) {
3112 		ret = dup_ref(cur, &pm->update_refs);
3113 		if (ret < 0)
3114 			goto out;
3115 	}
3116 	list_for_each_entry(cur, new_refs, list) {
3117 		ret = dup_ref(cur, &pm->update_refs);
3118 		if (ret < 0)
3119 			goto out;
3120 	}
3121 
3122 	ret = add_waiting_dir_move(sctx, pm->ino, is_orphan);
3123 	if (ret)
3124 		goto out;
3125 
3126 	if (exists) {
3127 		list_add_tail(&pm->list, &entry->list);
3128 	} else {
3129 		rb_link_node(&pm->node, parent, p);
3130 		rb_insert_color(&pm->node, &sctx->pending_dir_moves);
3131 	}
3132 	ret = 0;
3133 out:
3134 	if (ret) {
3135 		__free_recorded_refs(&pm->update_refs);
3136 		kfree(pm);
3137 	}
3138 	return ret;
3139 }
3140 
3141 static struct pending_dir_move *get_pending_dir_moves(struct send_ctx *sctx,
3142 						      u64 parent_ino)
3143 {
3144 	struct rb_node *n = sctx->pending_dir_moves.rb_node;
3145 	struct pending_dir_move *entry;
3146 
3147 	while (n) {
3148 		entry = rb_entry(n, struct pending_dir_move, node);
3149 		if (parent_ino < entry->parent_ino)
3150 			n = n->rb_left;
3151 		else if (parent_ino > entry->parent_ino)
3152 			n = n->rb_right;
3153 		else
3154 			return entry;
3155 	}
3156 	return NULL;
3157 }
3158 
3159 static int path_loop(struct send_ctx *sctx, struct fs_path *name,
3160 		     u64 ino, u64 gen, u64 *ancestor_ino)
3161 {
3162 	int ret = 0;
3163 	u64 parent_inode = 0;
3164 	u64 parent_gen = 0;
3165 	u64 start_ino = ino;
3166 
3167 	*ancestor_ino = 0;
3168 	while (ino != BTRFS_FIRST_FREE_OBJECTID) {
3169 		fs_path_reset(name);
3170 
3171 		if (is_waiting_for_rm(sctx, ino))
3172 			break;
3173 		if (is_waiting_for_move(sctx, ino)) {
3174 			if (*ancestor_ino == 0)
3175 				*ancestor_ino = ino;
3176 			ret = get_first_ref(sctx->parent_root, ino,
3177 					    &parent_inode, &parent_gen, name);
3178 		} else {
3179 			ret = __get_cur_name_and_parent(sctx, ino, gen,
3180 							&parent_inode,
3181 							&parent_gen, name);
3182 			if (ret > 0) {
3183 				ret = 0;
3184 				break;
3185 			}
3186 		}
3187 		if (ret < 0)
3188 			break;
3189 		if (parent_inode == start_ino) {
3190 			ret = 1;
3191 			if (*ancestor_ino == 0)
3192 				*ancestor_ino = ino;
3193 			break;
3194 		}
3195 		ino = parent_inode;
3196 		gen = parent_gen;
3197 	}
3198 	return ret;
3199 }
3200 
3201 static int apply_dir_move(struct send_ctx *sctx, struct pending_dir_move *pm)
3202 {
3203 	struct fs_path *from_path = NULL;
3204 	struct fs_path *to_path = NULL;
3205 	struct fs_path *name = NULL;
3206 	u64 orig_progress = sctx->send_progress;
3207 	struct recorded_ref *cur;
3208 	u64 parent_ino, parent_gen;
3209 	struct waiting_dir_move *dm = NULL;
3210 	u64 rmdir_ino = 0;
3211 	u64 ancestor;
3212 	bool is_orphan;
3213 	int ret;
3214 
3215 	name = fs_path_alloc();
3216 	from_path = fs_path_alloc();
3217 	if (!name || !from_path) {
3218 		ret = -ENOMEM;
3219 		goto out;
3220 	}
3221 
3222 	dm = get_waiting_dir_move(sctx, pm->ino);
3223 	ASSERT(dm);
3224 	rmdir_ino = dm->rmdir_ino;
3225 	is_orphan = dm->orphanized;
3226 	free_waiting_dir_move(sctx, dm);
3227 
3228 	if (is_orphan) {
3229 		ret = gen_unique_name(sctx, pm->ino,
3230 				      pm->gen, from_path);
3231 	} else {
3232 		ret = get_first_ref(sctx->parent_root, pm->ino,
3233 				    &parent_ino, &parent_gen, name);
3234 		if (ret < 0)
3235 			goto out;
3236 		ret = get_cur_path(sctx, parent_ino, parent_gen,
3237 				   from_path);
3238 		if (ret < 0)
3239 			goto out;
3240 		ret = fs_path_add_path(from_path, name);
3241 	}
3242 	if (ret < 0)
3243 		goto out;
3244 
3245 	sctx->send_progress = sctx->cur_ino + 1;
3246 	ret = path_loop(sctx, name, pm->ino, pm->gen, &ancestor);
3247 	if (ret < 0)
3248 		goto out;
3249 	if (ret) {
3250 		LIST_HEAD(deleted_refs);
3251 		ASSERT(ancestor > BTRFS_FIRST_FREE_OBJECTID);
3252 		ret = add_pending_dir_move(sctx, pm->ino, pm->gen, ancestor,
3253 					   &pm->update_refs, &deleted_refs,
3254 					   is_orphan);
3255 		if (ret < 0)
3256 			goto out;
3257 		if (rmdir_ino) {
3258 			dm = get_waiting_dir_move(sctx, pm->ino);
3259 			ASSERT(dm);
3260 			dm->rmdir_ino = rmdir_ino;
3261 		}
3262 		goto out;
3263 	}
3264 	fs_path_reset(name);
3265 	to_path = name;
3266 	name = NULL;
3267 	ret = get_cur_path(sctx, pm->ino, pm->gen, to_path);
3268 	if (ret < 0)
3269 		goto out;
3270 
3271 	ret = send_rename(sctx, from_path, to_path);
3272 	if (ret < 0)
3273 		goto out;
3274 
3275 	if (rmdir_ino) {
3276 		struct orphan_dir_info *odi;
3277 
3278 		odi = get_orphan_dir_info(sctx, rmdir_ino);
3279 		if (!odi) {
3280 			/* already deleted */
3281 			goto finish;
3282 		}
3283 		ret = can_rmdir(sctx, rmdir_ino, odi->gen, sctx->cur_ino);
3284 		if (ret < 0)
3285 			goto out;
3286 		if (!ret)
3287 			goto finish;
3288 
3289 		name = fs_path_alloc();
3290 		if (!name) {
3291 			ret = -ENOMEM;
3292 			goto out;
3293 		}
3294 		ret = get_cur_path(sctx, rmdir_ino, odi->gen, name);
3295 		if (ret < 0)
3296 			goto out;
3297 		ret = send_rmdir(sctx, name);
3298 		if (ret < 0)
3299 			goto out;
3300 		free_orphan_dir_info(sctx, odi);
3301 	}
3302 
3303 finish:
3304 	ret = send_utimes(sctx, pm->ino, pm->gen);
3305 	if (ret < 0)
3306 		goto out;
3307 
3308 	/*
3309 	 * After rename/move, need to update the utimes of both new parent(s)
3310 	 * and old parent(s).
3311 	 */
3312 	list_for_each_entry(cur, &pm->update_refs, list) {
3313 		/*
3314 		 * The parent inode might have been deleted in the send snapshot
3315 		 */
3316 		ret = get_inode_info(sctx->send_root, cur->dir, NULL,
3317 				     NULL, NULL, NULL, NULL, NULL);
3318 		if (ret == -ENOENT) {
3319 			ret = 0;
3320 			continue;
3321 		}
3322 		if (ret < 0)
3323 			goto out;
3324 
3325 		ret = send_utimes(sctx, cur->dir, cur->dir_gen);
3326 		if (ret < 0)
3327 			goto out;
3328 	}
3329 
3330 out:
3331 	fs_path_free(name);
3332 	fs_path_free(from_path);
3333 	fs_path_free(to_path);
3334 	sctx->send_progress = orig_progress;
3335 
3336 	return ret;
3337 }
3338 
3339 static void free_pending_move(struct send_ctx *sctx, struct pending_dir_move *m)
3340 {
3341 	if (!list_empty(&m->list))
3342 		list_del(&m->list);
3343 	if (!RB_EMPTY_NODE(&m->node))
3344 		rb_erase(&m->node, &sctx->pending_dir_moves);
3345 	__free_recorded_refs(&m->update_refs);
3346 	kfree(m);
3347 }
3348 
3349 static void tail_append_pending_moves(struct pending_dir_move *moves,
3350 				      struct list_head *stack)
3351 {
3352 	if (list_empty(&moves->list)) {
3353 		list_add_tail(&moves->list, stack);
3354 	} else {
3355 		LIST_HEAD(list);
3356 		list_splice_init(&moves->list, &list);
3357 		list_add_tail(&moves->list, stack);
3358 		list_splice_tail(&list, stack);
3359 	}
3360 }
3361 
3362 static int apply_children_dir_moves(struct send_ctx *sctx)
3363 {
3364 	struct pending_dir_move *pm;
3365 	struct list_head stack;
3366 	u64 parent_ino = sctx->cur_ino;
3367 	int ret = 0;
3368 
3369 	pm = get_pending_dir_moves(sctx, parent_ino);
3370 	if (!pm)
3371 		return 0;
3372 
3373 	INIT_LIST_HEAD(&stack);
3374 	tail_append_pending_moves(pm, &stack);
3375 
3376 	while (!list_empty(&stack)) {
3377 		pm = list_first_entry(&stack, struct pending_dir_move, list);
3378 		parent_ino = pm->ino;
3379 		ret = apply_dir_move(sctx, pm);
3380 		free_pending_move(sctx, pm);
3381 		if (ret)
3382 			goto out;
3383 		pm = get_pending_dir_moves(sctx, parent_ino);
3384 		if (pm)
3385 			tail_append_pending_moves(pm, &stack);
3386 	}
3387 	return 0;
3388 
3389 out:
3390 	while (!list_empty(&stack)) {
3391 		pm = list_first_entry(&stack, struct pending_dir_move, list);
3392 		free_pending_move(sctx, pm);
3393 	}
3394 	return ret;
3395 }
3396 
3397 /*
3398  * We might need to delay a directory rename even when no ancestor directory
3399  * (in the send root) with a higher inode number than ours (sctx->cur_ino) was
3400  * renamed. This happens when we rename a directory to the old name (the name
3401  * in the parent root) of some other unrelated directory that got its rename
3402  * delayed due to some ancestor with higher number that got renamed.
3403  *
3404  * Example:
3405  *
3406  * Parent snapshot:
3407  * .                                       (ino 256)
3408  * |---- a/                                (ino 257)
3409  * |     |---- file                        (ino 260)
3410  * |
3411  * |---- b/                                (ino 258)
3412  * |---- c/                                (ino 259)
3413  *
3414  * Send snapshot:
3415  * .                                       (ino 256)
3416  * |---- a/                                (ino 258)
3417  * |---- x/                                (ino 259)
3418  *       |---- y/                          (ino 257)
3419  *             |----- file                 (ino 260)
3420  *
3421  * Here we can not rename 258 from 'b' to 'a' without the rename of inode 257
3422  * from 'a' to 'x/y' happening first, which in turn depends on the rename of
3423  * inode 259 from 'c' to 'x'. So the order of rename commands the send stream
3424  * must issue is:
3425  *
3426  * 1 - rename 259 from 'c' to 'x'
3427  * 2 - rename 257 from 'a' to 'x/y'
3428  * 3 - rename 258 from 'b' to 'a'
3429  *
3430  * Returns 1 if the rename of sctx->cur_ino needs to be delayed, 0 if it can
3431  * be done right away and < 0 on error.
3432  */
3433 static int wait_for_dest_dir_move(struct send_ctx *sctx,
3434 				  struct recorded_ref *parent_ref,
3435 				  const bool is_orphan)
3436 {
3437 	struct btrfs_path *path;
3438 	struct btrfs_key key;
3439 	struct btrfs_key di_key;
3440 	struct btrfs_dir_item *di;
3441 	u64 left_gen;
3442 	u64 right_gen;
3443 	int ret = 0;
3444 	struct waiting_dir_move *wdm;
3445 
3446 	if (RB_EMPTY_ROOT(&sctx->waiting_dir_moves))
3447 		return 0;
3448 
3449 	path = alloc_path_for_send();
3450 	if (!path)
3451 		return -ENOMEM;
3452 
3453 	key.objectid = parent_ref->dir;
3454 	key.type = BTRFS_DIR_ITEM_KEY;
3455 	key.offset = btrfs_name_hash(parent_ref->name, parent_ref->name_len);
3456 
3457 	ret = btrfs_search_slot(NULL, sctx->parent_root, &key, path, 0, 0);
3458 	if (ret < 0) {
3459 		goto out;
3460 	} else if (ret > 0) {
3461 		ret = 0;
3462 		goto out;
3463 	}
3464 
3465 	di = btrfs_match_dir_item_name(sctx->parent_root, path,
3466 				       parent_ref->name, parent_ref->name_len);
3467 	if (!di) {
3468 		ret = 0;
3469 		goto out;
3470 	}
3471 	/*
3472 	 * di_key.objectid has the number of the inode that has a dentry in the
3473 	 * parent directory with the same name that sctx->cur_ino is being
3474 	 * renamed to. We need to check if that inode is in the send root as
3475 	 * well and if it is currently marked as an inode with a pending rename,
3476 	 * if it is, we need to delay the rename of sctx->cur_ino as well, so
3477 	 * that it happens after that other inode is renamed.
3478 	 */
3479 	btrfs_dir_item_key_to_cpu(path->nodes[0], di, &di_key);
3480 	if (di_key.type != BTRFS_INODE_ITEM_KEY) {
3481 		ret = 0;
3482 		goto out;
3483 	}
3484 
3485 	ret = get_inode_info(sctx->parent_root, di_key.objectid, NULL,
3486 			     &left_gen, NULL, NULL, NULL, NULL);
3487 	if (ret < 0)
3488 		goto out;
3489 	ret = get_inode_info(sctx->send_root, di_key.objectid, NULL,
3490 			     &right_gen, NULL, NULL, NULL, NULL);
3491 	if (ret < 0) {
3492 		if (ret == -ENOENT)
3493 			ret = 0;
3494 		goto out;
3495 	}
3496 
3497 	/* Different inode, no need to delay the rename of sctx->cur_ino */
3498 	if (right_gen != left_gen) {
3499 		ret = 0;
3500 		goto out;
3501 	}
3502 
3503 	wdm = get_waiting_dir_move(sctx, di_key.objectid);
3504 	if (wdm && !wdm->orphanized) {
3505 		ret = add_pending_dir_move(sctx,
3506 					   sctx->cur_ino,
3507 					   sctx->cur_inode_gen,
3508 					   di_key.objectid,
3509 					   &sctx->new_refs,
3510 					   &sctx->deleted_refs,
3511 					   is_orphan);
3512 		if (!ret)
3513 			ret = 1;
3514 	}
3515 out:
3516 	btrfs_free_path(path);
3517 	return ret;
3518 }
3519 
3520 /*
3521  * Check if ino ino1 is an ancestor of inode ino2 in the given root.
3522  * Return 1 if true, 0 if false and < 0 on error.
3523  */
3524 static int is_ancestor(struct btrfs_root *root,
3525 		       const u64 ino1,
3526 		       const u64 ino1_gen,
3527 		       const u64 ino2,
3528 		       struct fs_path *fs_path)
3529 {
3530 	u64 ino = ino2;
3531 
3532 	while (ino > BTRFS_FIRST_FREE_OBJECTID) {
3533 		int ret;
3534 		u64 parent;
3535 		u64 parent_gen;
3536 
3537 		fs_path_reset(fs_path);
3538 		ret = get_first_ref(root, ino, &parent, &parent_gen, fs_path);
3539 		if (ret < 0) {
3540 			if (ret == -ENOENT && ino == ino2)
3541 				ret = 0;
3542 			return ret;
3543 		}
3544 		if (parent == ino1)
3545 			return parent_gen == ino1_gen ? 1 : 0;
3546 		ino = parent;
3547 	}
3548 	return 0;
3549 }
3550 
3551 static int wait_for_parent_move(struct send_ctx *sctx,
3552 				struct recorded_ref *parent_ref,
3553 				const bool is_orphan)
3554 {
3555 	int ret = 0;
3556 	u64 ino = parent_ref->dir;
3557 	u64 parent_ino_before, parent_ino_after;
3558 	struct fs_path *path_before = NULL;
3559 	struct fs_path *path_after = NULL;
3560 	int len1, len2;
3561 
3562 	path_after = fs_path_alloc();
3563 	path_before = fs_path_alloc();
3564 	if (!path_after || !path_before) {
3565 		ret = -ENOMEM;
3566 		goto out;
3567 	}
3568 
3569 	/*
3570 	 * Our current directory inode may not yet be renamed/moved because some
3571 	 * ancestor (immediate or not) has to be renamed/moved first. So find if
3572 	 * such ancestor exists and make sure our own rename/move happens after
3573 	 * that ancestor is processed to avoid path build infinite loops (done
3574 	 * at get_cur_path()).
3575 	 */
3576 	while (ino > BTRFS_FIRST_FREE_OBJECTID) {
3577 		if (is_waiting_for_move(sctx, ino)) {
3578 			/*
3579 			 * If the current inode is an ancestor of ino in the
3580 			 * parent root, we need to delay the rename of the
3581 			 * current inode, otherwise don't delayed the rename
3582 			 * because we can end up with a circular dependency
3583 			 * of renames, resulting in some directories never
3584 			 * getting the respective rename operations issued in
3585 			 * the send stream or getting into infinite path build
3586 			 * loops.
3587 			 */
3588 			ret = is_ancestor(sctx->parent_root,
3589 					  sctx->cur_ino, sctx->cur_inode_gen,
3590 					  ino, path_before);
3591 			if (ret)
3592 				break;
3593 		}
3594 
3595 		fs_path_reset(path_before);
3596 		fs_path_reset(path_after);
3597 
3598 		ret = get_first_ref(sctx->send_root, ino, &parent_ino_after,
3599 				    NULL, path_after);
3600 		if (ret < 0)
3601 			goto out;
3602 		ret = get_first_ref(sctx->parent_root, ino, &parent_ino_before,
3603 				    NULL, path_before);
3604 		if (ret < 0 && ret != -ENOENT) {
3605 			goto out;
3606 		} else if (ret == -ENOENT) {
3607 			ret = 0;
3608 			break;
3609 		}
3610 
3611 		len1 = fs_path_len(path_before);
3612 		len2 = fs_path_len(path_after);
3613 		if (ino > sctx->cur_ino &&
3614 		    (parent_ino_before != parent_ino_after || len1 != len2 ||
3615 		     memcmp(path_before->start, path_after->start, len1))) {
3616 			ret = 1;
3617 			break;
3618 		}
3619 		ino = parent_ino_after;
3620 	}
3621 
3622 out:
3623 	fs_path_free(path_before);
3624 	fs_path_free(path_after);
3625 
3626 	if (ret == 1) {
3627 		ret = add_pending_dir_move(sctx,
3628 					   sctx->cur_ino,
3629 					   sctx->cur_inode_gen,
3630 					   ino,
3631 					   &sctx->new_refs,
3632 					   &sctx->deleted_refs,
3633 					   is_orphan);
3634 		if (!ret)
3635 			ret = 1;
3636 	}
3637 
3638 	return ret;
3639 }
3640 
3641 /*
3642  * This does all the move/link/unlink/rmdir magic.
3643  */
3644 static int process_recorded_refs(struct send_ctx *sctx, int *pending_move)
3645 {
3646 	struct btrfs_fs_info *fs_info = sctx->send_root->fs_info;
3647 	int ret = 0;
3648 	struct recorded_ref *cur;
3649 	struct recorded_ref *cur2;
3650 	struct list_head check_dirs;
3651 	struct fs_path *valid_path = NULL;
3652 	u64 ow_inode = 0;
3653 	u64 ow_gen;
3654 	int did_overwrite = 0;
3655 	int is_orphan = 0;
3656 	u64 last_dir_ino_rm = 0;
3657 	bool can_rename = true;
3658 
3659 	btrfs_debug(fs_info, "process_recorded_refs %llu", sctx->cur_ino);
3660 
3661 	/*
3662 	 * This should never happen as the root dir always has the same ref
3663 	 * which is always '..'
3664 	 */
3665 	BUG_ON(sctx->cur_ino <= BTRFS_FIRST_FREE_OBJECTID);
3666 	INIT_LIST_HEAD(&check_dirs);
3667 
3668 	valid_path = fs_path_alloc();
3669 	if (!valid_path) {
3670 		ret = -ENOMEM;
3671 		goto out;
3672 	}
3673 
3674 	/*
3675 	 * First, check if the first ref of the current inode was overwritten
3676 	 * before. If yes, we know that the current inode was already orphanized
3677 	 * and thus use the orphan name. If not, we can use get_cur_path to
3678 	 * get the path of the first ref as it would like while receiving at
3679 	 * this point in time.
3680 	 * New inodes are always orphan at the beginning, so force to use the
3681 	 * orphan name in this case.
3682 	 * The first ref is stored in valid_path and will be updated if it
3683 	 * gets moved around.
3684 	 */
3685 	if (!sctx->cur_inode_new) {
3686 		ret = did_overwrite_first_ref(sctx, sctx->cur_ino,
3687 				sctx->cur_inode_gen);
3688 		if (ret < 0)
3689 			goto out;
3690 		if (ret)
3691 			did_overwrite = 1;
3692 	}
3693 	if (sctx->cur_inode_new || did_overwrite) {
3694 		ret = gen_unique_name(sctx, sctx->cur_ino,
3695 				sctx->cur_inode_gen, valid_path);
3696 		if (ret < 0)
3697 			goto out;
3698 		is_orphan = 1;
3699 	} else {
3700 		ret = get_cur_path(sctx, sctx->cur_ino, sctx->cur_inode_gen,
3701 				valid_path);
3702 		if (ret < 0)
3703 			goto out;
3704 	}
3705 
3706 	list_for_each_entry(cur, &sctx->new_refs, list) {
3707 		/*
3708 		 * We may have refs where the parent directory does not exist
3709 		 * yet. This happens if the parent directories inum is higher
3710 		 * the the current inum. To handle this case, we create the
3711 		 * parent directory out of order. But we need to check if this
3712 		 * did already happen before due to other refs in the same dir.
3713 		 */
3714 		ret = get_cur_inode_state(sctx, cur->dir, cur->dir_gen);
3715 		if (ret < 0)
3716 			goto out;
3717 		if (ret == inode_state_will_create) {
3718 			ret = 0;
3719 			/*
3720 			 * First check if any of the current inodes refs did
3721 			 * already create the dir.
3722 			 */
3723 			list_for_each_entry(cur2, &sctx->new_refs, list) {
3724 				if (cur == cur2)
3725 					break;
3726 				if (cur2->dir == cur->dir) {
3727 					ret = 1;
3728 					break;
3729 				}
3730 			}
3731 
3732 			/*
3733 			 * If that did not happen, check if a previous inode
3734 			 * did already create the dir.
3735 			 */
3736 			if (!ret)
3737 				ret = did_create_dir(sctx, cur->dir);
3738 			if (ret < 0)
3739 				goto out;
3740 			if (!ret) {
3741 				ret = send_create_inode(sctx, cur->dir);
3742 				if (ret < 0)
3743 					goto out;
3744 			}
3745 		}
3746 
3747 		/*
3748 		 * Check if this new ref would overwrite the first ref of
3749 		 * another unprocessed inode. If yes, orphanize the
3750 		 * overwritten inode. If we find an overwritten ref that is
3751 		 * not the first ref, simply unlink it.
3752 		 */
3753 		ret = will_overwrite_ref(sctx, cur->dir, cur->dir_gen,
3754 				cur->name, cur->name_len,
3755 				&ow_inode, &ow_gen);
3756 		if (ret < 0)
3757 			goto out;
3758 		if (ret) {
3759 			ret = is_first_ref(sctx->parent_root,
3760 					   ow_inode, cur->dir, cur->name,
3761 					   cur->name_len);
3762 			if (ret < 0)
3763 				goto out;
3764 			if (ret) {
3765 				struct name_cache_entry *nce;
3766 				struct waiting_dir_move *wdm;
3767 
3768 				ret = orphanize_inode(sctx, ow_inode, ow_gen,
3769 						cur->full_path);
3770 				if (ret < 0)
3771 					goto out;
3772 
3773 				/*
3774 				 * If ow_inode has its rename operation delayed
3775 				 * make sure that its orphanized name is used in
3776 				 * the source path when performing its rename
3777 				 * operation.
3778 				 */
3779 				if (is_waiting_for_move(sctx, ow_inode)) {
3780 					wdm = get_waiting_dir_move(sctx,
3781 								   ow_inode);
3782 					ASSERT(wdm);
3783 					wdm->orphanized = true;
3784 				}
3785 
3786 				/*
3787 				 * Make sure we clear our orphanized inode's
3788 				 * name from the name cache. This is because the
3789 				 * inode ow_inode might be an ancestor of some
3790 				 * other inode that will be orphanized as well
3791 				 * later and has an inode number greater than
3792 				 * sctx->send_progress. We need to prevent
3793 				 * future name lookups from using the old name
3794 				 * and get instead the orphan name.
3795 				 */
3796 				nce = name_cache_search(sctx, ow_inode, ow_gen);
3797 				if (nce) {
3798 					name_cache_delete(sctx, nce);
3799 					kfree(nce);
3800 				}
3801 
3802 				/*
3803 				 * ow_inode might currently be an ancestor of
3804 				 * cur_ino, therefore compute valid_path (the
3805 				 * current path of cur_ino) again because it
3806 				 * might contain the pre-orphanization name of
3807 				 * ow_inode, which is no longer valid.
3808 				 */
3809 				fs_path_reset(valid_path);
3810 				ret = get_cur_path(sctx, sctx->cur_ino,
3811 					   sctx->cur_inode_gen, valid_path);
3812 				if (ret < 0)
3813 					goto out;
3814 			} else {
3815 				ret = send_unlink(sctx, cur->full_path);
3816 				if (ret < 0)
3817 					goto out;
3818 			}
3819 		}
3820 
3821 		if (S_ISDIR(sctx->cur_inode_mode) && sctx->parent_root) {
3822 			ret = wait_for_dest_dir_move(sctx, cur, is_orphan);
3823 			if (ret < 0)
3824 				goto out;
3825 			if (ret == 1) {
3826 				can_rename = false;
3827 				*pending_move = 1;
3828 			}
3829 		}
3830 
3831 		if (S_ISDIR(sctx->cur_inode_mode) && sctx->parent_root &&
3832 		    can_rename) {
3833 			ret = wait_for_parent_move(sctx, cur, is_orphan);
3834 			if (ret < 0)
3835 				goto out;
3836 			if (ret == 1) {
3837 				can_rename = false;
3838 				*pending_move = 1;
3839 			}
3840 		}
3841 
3842 		/*
3843 		 * link/move the ref to the new place. If we have an orphan
3844 		 * inode, move it and update valid_path. If not, link or move
3845 		 * it depending on the inode mode.
3846 		 */
3847 		if (is_orphan && can_rename) {
3848 			ret = send_rename(sctx, valid_path, cur->full_path);
3849 			if (ret < 0)
3850 				goto out;
3851 			is_orphan = 0;
3852 			ret = fs_path_copy(valid_path, cur->full_path);
3853 			if (ret < 0)
3854 				goto out;
3855 		} else if (can_rename) {
3856 			if (S_ISDIR(sctx->cur_inode_mode)) {
3857 				/*
3858 				 * Dirs can't be linked, so move it. For moved
3859 				 * dirs, we always have one new and one deleted
3860 				 * ref. The deleted ref is ignored later.
3861 				 */
3862 				ret = send_rename(sctx, valid_path,
3863 						  cur->full_path);
3864 				if (!ret)
3865 					ret = fs_path_copy(valid_path,
3866 							   cur->full_path);
3867 				if (ret < 0)
3868 					goto out;
3869 			} else {
3870 				ret = send_link(sctx, cur->full_path,
3871 						valid_path);
3872 				if (ret < 0)
3873 					goto out;
3874 			}
3875 		}
3876 		ret = dup_ref(cur, &check_dirs);
3877 		if (ret < 0)
3878 			goto out;
3879 	}
3880 
3881 	if (S_ISDIR(sctx->cur_inode_mode) && sctx->cur_inode_deleted) {
3882 		/*
3883 		 * Check if we can already rmdir the directory. If not,
3884 		 * orphanize it. For every dir item inside that gets deleted
3885 		 * later, we do this check again and rmdir it then if possible.
3886 		 * See the use of check_dirs for more details.
3887 		 */
3888 		ret = can_rmdir(sctx, sctx->cur_ino, sctx->cur_inode_gen,
3889 				sctx->cur_ino);
3890 		if (ret < 0)
3891 			goto out;
3892 		if (ret) {
3893 			ret = send_rmdir(sctx, valid_path);
3894 			if (ret < 0)
3895 				goto out;
3896 		} else if (!is_orphan) {
3897 			ret = orphanize_inode(sctx, sctx->cur_ino,
3898 					sctx->cur_inode_gen, valid_path);
3899 			if (ret < 0)
3900 				goto out;
3901 			is_orphan = 1;
3902 		}
3903 
3904 		list_for_each_entry(cur, &sctx->deleted_refs, list) {
3905 			ret = dup_ref(cur, &check_dirs);
3906 			if (ret < 0)
3907 				goto out;
3908 		}
3909 	} else if (S_ISDIR(sctx->cur_inode_mode) &&
3910 		   !list_empty(&sctx->deleted_refs)) {
3911 		/*
3912 		 * We have a moved dir. Add the old parent to check_dirs
3913 		 */
3914 		cur = list_entry(sctx->deleted_refs.next, struct recorded_ref,
3915 				list);
3916 		ret = dup_ref(cur, &check_dirs);
3917 		if (ret < 0)
3918 			goto out;
3919 	} else if (!S_ISDIR(sctx->cur_inode_mode)) {
3920 		/*
3921 		 * We have a non dir inode. Go through all deleted refs and
3922 		 * unlink them if they were not already overwritten by other
3923 		 * inodes.
3924 		 */
3925 		list_for_each_entry(cur, &sctx->deleted_refs, list) {
3926 			ret = did_overwrite_ref(sctx, cur->dir, cur->dir_gen,
3927 					sctx->cur_ino, sctx->cur_inode_gen,
3928 					cur->name, cur->name_len);
3929 			if (ret < 0)
3930 				goto out;
3931 			if (!ret) {
3932 				ret = send_unlink(sctx, cur->full_path);
3933 				if (ret < 0)
3934 					goto out;
3935 			}
3936 			ret = dup_ref(cur, &check_dirs);
3937 			if (ret < 0)
3938 				goto out;
3939 		}
3940 		/*
3941 		 * If the inode is still orphan, unlink the orphan. This may
3942 		 * happen when a previous inode did overwrite the first ref
3943 		 * of this inode and no new refs were added for the current
3944 		 * inode. Unlinking does not mean that the inode is deleted in
3945 		 * all cases. There may still be links to this inode in other
3946 		 * places.
3947 		 */
3948 		if (is_orphan) {
3949 			ret = send_unlink(sctx, valid_path);
3950 			if (ret < 0)
3951 				goto out;
3952 		}
3953 	}
3954 
3955 	/*
3956 	 * We did collect all parent dirs where cur_inode was once located. We
3957 	 * now go through all these dirs and check if they are pending for
3958 	 * deletion and if it's finally possible to perform the rmdir now.
3959 	 * We also update the inode stats of the parent dirs here.
3960 	 */
3961 	list_for_each_entry(cur, &check_dirs, list) {
3962 		/*
3963 		 * In case we had refs into dirs that were not processed yet,
3964 		 * we don't need to do the utime and rmdir logic for these dirs.
3965 		 * The dir will be processed later.
3966 		 */
3967 		if (cur->dir > sctx->cur_ino)
3968 			continue;
3969 
3970 		ret = get_cur_inode_state(sctx, cur->dir, cur->dir_gen);
3971 		if (ret < 0)
3972 			goto out;
3973 
3974 		if (ret == inode_state_did_create ||
3975 		    ret == inode_state_no_change) {
3976 			/* TODO delayed utimes */
3977 			ret = send_utimes(sctx, cur->dir, cur->dir_gen);
3978 			if (ret < 0)
3979 				goto out;
3980 		} else if (ret == inode_state_did_delete &&
3981 			   cur->dir != last_dir_ino_rm) {
3982 			ret = can_rmdir(sctx, cur->dir, cur->dir_gen,
3983 					sctx->cur_ino);
3984 			if (ret < 0)
3985 				goto out;
3986 			if (ret) {
3987 				ret = get_cur_path(sctx, cur->dir,
3988 						   cur->dir_gen, valid_path);
3989 				if (ret < 0)
3990 					goto out;
3991 				ret = send_rmdir(sctx, valid_path);
3992 				if (ret < 0)
3993 					goto out;
3994 				last_dir_ino_rm = cur->dir;
3995 			}
3996 		}
3997 	}
3998 
3999 	ret = 0;
4000 
4001 out:
4002 	__free_recorded_refs(&check_dirs);
4003 	free_recorded_refs(sctx);
4004 	fs_path_free(valid_path);
4005 	return ret;
4006 }
4007 
4008 static int record_ref(struct btrfs_root *root, int num, u64 dir, int index,
4009 		      struct fs_path *name, void *ctx, struct list_head *refs)
4010 {
4011 	int ret = 0;
4012 	struct send_ctx *sctx = ctx;
4013 	struct fs_path *p;
4014 	u64 gen;
4015 
4016 	p = fs_path_alloc();
4017 	if (!p)
4018 		return -ENOMEM;
4019 
4020 	ret = get_inode_info(root, dir, NULL, &gen, NULL, NULL,
4021 			NULL, NULL);
4022 	if (ret < 0)
4023 		goto out;
4024 
4025 	ret = get_cur_path(sctx, dir, gen, p);
4026 	if (ret < 0)
4027 		goto out;
4028 	ret = fs_path_add_path(p, name);
4029 	if (ret < 0)
4030 		goto out;
4031 
4032 	ret = __record_ref(refs, dir, gen, p);
4033 
4034 out:
4035 	if (ret)
4036 		fs_path_free(p);
4037 	return ret;
4038 }
4039 
4040 static int __record_new_ref(int num, u64 dir, int index,
4041 			    struct fs_path *name,
4042 			    void *ctx)
4043 {
4044 	struct send_ctx *sctx = ctx;
4045 	return record_ref(sctx->send_root, num, dir, index, name,
4046 			  ctx, &sctx->new_refs);
4047 }
4048 
4049 
4050 static int __record_deleted_ref(int num, u64 dir, int index,
4051 				struct fs_path *name,
4052 				void *ctx)
4053 {
4054 	struct send_ctx *sctx = ctx;
4055 	return record_ref(sctx->parent_root, num, dir, index, name,
4056 			  ctx, &sctx->deleted_refs);
4057 }
4058 
4059 static int record_new_ref(struct send_ctx *sctx)
4060 {
4061 	int ret;
4062 
4063 	ret = iterate_inode_ref(sctx->send_root, sctx->left_path,
4064 				sctx->cmp_key, 0, __record_new_ref, sctx);
4065 	if (ret < 0)
4066 		goto out;
4067 	ret = 0;
4068 
4069 out:
4070 	return ret;
4071 }
4072 
4073 static int record_deleted_ref(struct send_ctx *sctx)
4074 {
4075 	int ret;
4076 
4077 	ret = iterate_inode_ref(sctx->parent_root, sctx->right_path,
4078 				sctx->cmp_key, 0, __record_deleted_ref, sctx);
4079 	if (ret < 0)
4080 		goto out;
4081 	ret = 0;
4082 
4083 out:
4084 	return ret;
4085 }
4086 
4087 struct find_ref_ctx {
4088 	u64 dir;
4089 	u64 dir_gen;
4090 	struct btrfs_root *root;
4091 	struct fs_path *name;
4092 	int found_idx;
4093 };
4094 
4095 static int __find_iref(int num, u64 dir, int index,
4096 		       struct fs_path *name,
4097 		       void *ctx_)
4098 {
4099 	struct find_ref_ctx *ctx = ctx_;
4100 	u64 dir_gen;
4101 	int ret;
4102 
4103 	if (dir == ctx->dir && fs_path_len(name) == fs_path_len(ctx->name) &&
4104 	    strncmp(name->start, ctx->name->start, fs_path_len(name)) == 0) {
4105 		/*
4106 		 * To avoid doing extra lookups we'll only do this if everything
4107 		 * else matches.
4108 		 */
4109 		ret = get_inode_info(ctx->root, dir, NULL, &dir_gen, NULL,
4110 				     NULL, NULL, NULL);
4111 		if (ret)
4112 			return ret;
4113 		if (dir_gen != ctx->dir_gen)
4114 			return 0;
4115 		ctx->found_idx = num;
4116 		return 1;
4117 	}
4118 	return 0;
4119 }
4120 
4121 static int find_iref(struct btrfs_root *root,
4122 		     struct btrfs_path *path,
4123 		     struct btrfs_key *key,
4124 		     u64 dir, u64 dir_gen, struct fs_path *name)
4125 {
4126 	int ret;
4127 	struct find_ref_ctx ctx;
4128 
4129 	ctx.dir = dir;
4130 	ctx.name = name;
4131 	ctx.dir_gen = dir_gen;
4132 	ctx.found_idx = -1;
4133 	ctx.root = root;
4134 
4135 	ret = iterate_inode_ref(root, path, key, 0, __find_iref, &ctx);
4136 	if (ret < 0)
4137 		return ret;
4138 
4139 	if (ctx.found_idx == -1)
4140 		return -ENOENT;
4141 
4142 	return ctx.found_idx;
4143 }
4144 
4145 static int __record_changed_new_ref(int num, u64 dir, int index,
4146 				    struct fs_path *name,
4147 				    void *ctx)
4148 {
4149 	u64 dir_gen;
4150 	int ret;
4151 	struct send_ctx *sctx = ctx;
4152 
4153 	ret = get_inode_info(sctx->send_root, dir, NULL, &dir_gen, NULL,
4154 			     NULL, NULL, NULL);
4155 	if (ret)
4156 		return ret;
4157 
4158 	ret = find_iref(sctx->parent_root, sctx->right_path,
4159 			sctx->cmp_key, dir, dir_gen, name);
4160 	if (ret == -ENOENT)
4161 		ret = __record_new_ref(num, dir, index, name, sctx);
4162 	else if (ret > 0)
4163 		ret = 0;
4164 
4165 	return ret;
4166 }
4167 
4168 static int __record_changed_deleted_ref(int num, u64 dir, int index,
4169 					struct fs_path *name,
4170 					void *ctx)
4171 {
4172 	u64 dir_gen;
4173 	int ret;
4174 	struct send_ctx *sctx = ctx;
4175 
4176 	ret = get_inode_info(sctx->parent_root, dir, NULL, &dir_gen, NULL,
4177 			     NULL, NULL, NULL);
4178 	if (ret)
4179 		return ret;
4180 
4181 	ret = find_iref(sctx->send_root, sctx->left_path, sctx->cmp_key,
4182 			dir, dir_gen, name);
4183 	if (ret == -ENOENT)
4184 		ret = __record_deleted_ref(num, dir, index, name, sctx);
4185 	else if (ret > 0)
4186 		ret = 0;
4187 
4188 	return ret;
4189 }
4190 
4191 static int record_changed_ref(struct send_ctx *sctx)
4192 {
4193 	int ret = 0;
4194 
4195 	ret = iterate_inode_ref(sctx->send_root, sctx->left_path,
4196 			sctx->cmp_key, 0, __record_changed_new_ref, sctx);
4197 	if (ret < 0)
4198 		goto out;
4199 	ret = iterate_inode_ref(sctx->parent_root, sctx->right_path,
4200 			sctx->cmp_key, 0, __record_changed_deleted_ref, sctx);
4201 	if (ret < 0)
4202 		goto out;
4203 	ret = 0;
4204 
4205 out:
4206 	return ret;
4207 }
4208 
4209 /*
4210  * Record and process all refs at once. Needed when an inode changes the
4211  * generation number, which means that it was deleted and recreated.
4212  */
4213 static int process_all_refs(struct send_ctx *sctx,
4214 			    enum btrfs_compare_tree_result cmd)
4215 {
4216 	int ret;
4217 	struct btrfs_root *root;
4218 	struct btrfs_path *path;
4219 	struct btrfs_key key;
4220 	struct btrfs_key found_key;
4221 	struct extent_buffer *eb;
4222 	int slot;
4223 	iterate_inode_ref_t cb;
4224 	int pending_move = 0;
4225 
4226 	path = alloc_path_for_send();
4227 	if (!path)
4228 		return -ENOMEM;
4229 
4230 	if (cmd == BTRFS_COMPARE_TREE_NEW) {
4231 		root = sctx->send_root;
4232 		cb = __record_new_ref;
4233 	} else if (cmd == BTRFS_COMPARE_TREE_DELETED) {
4234 		root = sctx->parent_root;
4235 		cb = __record_deleted_ref;
4236 	} else {
4237 		btrfs_err(sctx->send_root->fs_info,
4238 				"Wrong command %d in process_all_refs", cmd);
4239 		ret = -EINVAL;
4240 		goto out;
4241 	}
4242 
4243 	key.objectid = sctx->cmp_key->objectid;
4244 	key.type = BTRFS_INODE_REF_KEY;
4245 	key.offset = 0;
4246 	ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
4247 	if (ret < 0)
4248 		goto out;
4249 
4250 	while (1) {
4251 		eb = path->nodes[0];
4252 		slot = path->slots[0];
4253 		if (slot >= btrfs_header_nritems(eb)) {
4254 			ret = btrfs_next_leaf(root, path);
4255 			if (ret < 0)
4256 				goto out;
4257 			else if (ret > 0)
4258 				break;
4259 			continue;
4260 		}
4261 
4262 		btrfs_item_key_to_cpu(eb, &found_key, slot);
4263 
4264 		if (found_key.objectid != key.objectid ||
4265 		    (found_key.type != BTRFS_INODE_REF_KEY &&
4266 		     found_key.type != BTRFS_INODE_EXTREF_KEY))
4267 			break;
4268 
4269 		ret = iterate_inode_ref(root, path, &found_key, 0, cb, sctx);
4270 		if (ret < 0)
4271 			goto out;
4272 
4273 		path->slots[0]++;
4274 	}
4275 	btrfs_release_path(path);
4276 
4277 	/*
4278 	 * We don't actually care about pending_move as we are simply
4279 	 * re-creating this inode and will be rename'ing it into place once we
4280 	 * rename the parent directory.
4281 	 */
4282 	ret = process_recorded_refs(sctx, &pending_move);
4283 out:
4284 	btrfs_free_path(path);
4285 	return ret;
4286 }
4287 
4288 static int send_set_xattr(struct send_ctx *sctx,
4289 			  struct fs_path *path,
4290 			  const char *name, int name_len,
4291 			  const char *data, int data_len)
4292 {
4293 	int ret = 0;
4294 
4295 	ret = begin_cmd(sctx, BTRFS_SEND_C_SET_XATTR);
4296 	if (ret < 0)
4297 		goto out;
4298 
4299 	TLV_PUT_PATH(sctx, BTRFS_SEND_A_PATH, path);
4300 	TLV_PUT_STRING(sctx, BTRFS_SEND_A_XATTR_NAME, name, name_len);
4301 	TLV_PUT(sctx, BTRFS_SEND_A_XATTR_DATA, data, data_len);
4302 
4303 	ret = send_cmd(sctx);
4304 
4305 tlv_put_failure:
4306 out:
4307 	return ret;
4308 }
4309 
4310 static int send_remove_xattr(struct send_ctx *sctx,
4311 			  struct fs_path *path,
4312 			  const char *name, int name_len)
4313 {
4314 	int ret = 0;
4315 
4316 	ret = begin_cmd(sctx, BTRFS_SEND_C_REMOVE_XATTR);
4317 	if (ret < 0)
4318 		goto out;
4319 
4320 	TLV_PUT_PATH(sctx, BTRFS_SEND_A_PATH, path);
4321 	TLV_PUT_STRING(sctx, BTRFS_SEND_A_XATTR_NAME, name, name_len);
4322 
4323 	ret = send_cmd(sctx);
4324 
4325 tlv_put_failure:
4326 out:
4327 	return ret;
4328 }
4329 
4330 static int __process_new_xattr(int num, struct btrfs_key *di_key,
4331 			       const char *name, int name_len,
4332 			       const char *data, int data_len,
4333 			       u8 type, void *ctx)
4334 {
4335 	int ret;
4336 	struct send_ctx *sctx = ctx;
4337 	struct fs_path *p;
4338 	struct posix_acl_xattr_header dummy_acl;
4339 
4340 	p = fs_path_alloc();
4341 	if (!p)
4342 		return -ENOMEM;
4343 
4344 	/*
4345 	 * This hack is needed because empty acls are stored as zero byte
4346 	 * data in xattrs. Problem with that is, that receiving these zero byte
4347 	 * acls will fail later. To fix this, we send a dummy acl list that
4348 	 * only contains the version number and no entries.
4349 	 */
4350 	if (!strncmp(name, XATTR_NAME_POSIX_ACL_ACCESS, name_len) ||
4351 	    !strncmp(name, XATTR_NAME_POSIX_ACL_DEFAULT, name_len)) {
4352 		if (data_len == 0) {
4353 			dummy_acl.a_version =
4354 					cpu_to_le32(POSIX_ACL_XATTR_VERSION);
4355 			data = (char *)&dummy_acl;
4356 			data_len = sizeof(dummy_acl);
4357 		}
4358 	}
4359 
4360 	ret = get_cur_path(sctx, sctx->cur_ino, sctx->cur_inode_gen, p);
4361 	if (ret < 0)
4362 		goto out;
4363 
4364 	ret = send_set_xattr(sctx, p, name, name_len, data, data_len);
4365 
4366 out:
4367 	fs_path_free(p);
4368 	return ret;
4369 }
4370 
4371 static int __process_deleted_xattr(int num, struct btrfs_key *di_key,
4372 				   const char *name, int name_len,
4373 				   const char *data, int data_len,
4374 				   u8 type, void *ctx)
4375 {
4376 	int ret;
4377 	struct send_ctx *sctx = ctx;
4378 	struct fs_path *p;
4379 
4380 	p = fs_path_alloc();
4381 	if (!p)
4382 		return -ENOMEM;
4383 
4384 	ret = get_cur_path(sctx, sctx->cur_ino, sctx->cur_inode_gen, p);
4385 	if (ret < 0)
4386 		goto out;
4387 
4388 	ret = send_remove_xattr(sctx, p, name, name_len);
4389 
4390 out:
4391 	fs_path_free(p);
4392 	return ret;
4393 }
4394 
4395 static int process_new_xattr(struct send_ctx *sctx)
4396 {
4397 	int ret = 0;
4398 
4399 	ret = iterate_dir_item(sctx->send_root, sctx->left_path,
4400 			       sctx->cmp_key, __process_new_xattr, sctx);
4401 
4402 	return ret;
4403 }
4404 
4405 static int process_deleted_xattr(struct send_ctx *sctx)
4406 {
4407 	return iterate_dir_item(sctx->parent_root, sctx->right_path,
4408 				sctx->cmp_key, __process_deleted_xattr, sctx);
4409 }
4410 
4411 struct find_xattr_ctx {
4412 	const char *name;
4413 	int name_len;
4414 	int found_idx;
4415 	char *found_data;
4416 	int found_data_len;
4417 };
4418 
4419 static int __find_xattr(int num, struct btrfs_key *di_key,
4420 			const char *name, int name_len,
4421 			const char *data, int data_len,
4422 			u8 type, void *vctx)
4423 {
4424 	struct find_xattr_ctx *ctx = vctx;
4425 
4426 	if (name_len == ctx->name_len &&
4427 	    strncmp(name, ctx->name, name_len) == 0) {
4428 		ctx->found_idx = num;
4429 		ctx->found_data_len = data_len;
4430 		ctx->found_data = kmemdup(data, data_len, GFP_KERNEL);
4431 		if (!ctx->found_data)
4432 			return -ENOMEM;
4433 		return 1;
4434 	}
4435 	return 0;
4436 }
4437 
4438 static int find_xattr(struct btrfs_root *root,
4439 		      struct btrfs_path *path,
4440 		      struct btrfs_key *key,
4441 		      const char *name, int name_len,
4442 		      char **data, int *data_len)
4443 {
4444 	int ret;
4445 	struct find_xattr_ctx ctx;
4446 
4447 	ctx.name = name;
4448 	ctx.name_len = name_len;
4449 	ctx.found_idx = -1;
4450 	ctx.found_data = NULL;
4451 	ctx.found_data_len = 0;
4452 
4453 	ret = iterate_dir_item(root, path, key, __find_xattr, &ctx);
4454 	if (ret < 0)
4455 		return ret;
4456 
4457 	if (ctx.found_idx == -1)
4458 		return -ENOENT;
4459 	if (data) {
4460 		*data = ctx.found_data;
4461 		*data_len = ctx.found_data_len;
4462 	} else {
4463 		kfree(ctx.found_data);
4464 	}
4465 	return ctx.found_idx;
4466 }
4467 
4468 
4469 static int __process_changed_new_xattr(int num, struct btrfs_key *di_key,
4470 				       const char *name, int name_len,
4471 				       const char *data, int data_len,
4472 				       u8 type, void *ctx)
4473 {
4474 	int ret;
4475 	struct send_ctx *sctx = ctx;
4476 	char *found_data = NULL;
4477 	int found_data_len  = 0;
4478 
4479 	ret = find_xattr(sctx->parent_root, sctx->right_path,
4480 			 sctx->cmp_key, name, name_len, &found_data,
4481 			 &found_data_len);
4482 	if (ret == -ENOENT) {
4483 		ret = __process_new_xattr(num, di_key, name, name_len, data,
4484 				data_len, type, ctx);
4485 	} else if (ret >= 0) {
4486 		if (data_len != found_data_len ||
4487 		    memcmp(data, found_data, data_len)) {
4488 			ret = __process_new_xattr(num, di_key, name, name_len,
4489 					data, data_len, type, ctx);
4490 		} else {
4491 			ret = 0;
4492 		}
4493 	}
4494 
4495 	kfree(found_data);
4496 	return ret;
4497 }
4498 
4499 static int __process_changed_deleted_xattr(int num, struct btrfs_key *di_key,
4500 					   const char *name, int name_len,
4501 					   const char *data, int data_len,
4502 					   u8 type, void *ctx)
4503 {
4504 	int ret;
4505 	struct send_ctx *sctx = ctx;
4506 
4507 	ret = find_xattr(sctx->send_root, sctx->left_path, sctx->cmp_key,
4508 			 name, name_len, NULL, NULL);
4509 	if (ret == -ENOENT)
4510 		ret = __process_deleted_xattr(num, di_key, name, name_len, data,
4511 				data_len, type, ctx);
4512 	else if (ret >= 0)
4513 		ret = 0;
4514 
4515 	return ret;
4516 }
4517 
4518 static int process_changed_xattr(struct send_ctx *sctx)
4519 {
4520 	int ret = 0;
4521 
4522 	ret = iterate_dir_item(sctx->send_root, sctx->left_path,
4523 			sctx->cmp_key, __process_changed_new_xattr, sctx);
4524 	if (ret < 0)
4525 		goto out;
4526 	ret = iterate_dir_item(sctx->parent_root, sctx->right_path,
4527 			sctx->cmp_key, __process_changed_deleted_xattr, sctx);
4528 
4529 out:
4530 	return ret;
4531 }
4532 
4533 static int process_all_new_xattrs(struct send_ctx *sctx)
4534 {
4535 	int ret;
4536 	struct btrfs_root *root;
4537 	struct btrfs_path *path;
4538 	struct btrfs_key key;
4539 	struct btrfs_key found_key;
4540 	struct extent_buffer *eb;
4541 	int slot;
4542 
4543 	path = alloc_path_for_send();
4544 	if (!path)
4545 		return -ENOMEM;
4546 
4547 	root = sctx->send_root;
4548 
4549 	key.objectid = sctx->cmp_key->objectid;
4550 	key.type = BTRFS_XATTR_ITEM_KEY;
4551 	key.offset = 0;
4552 	ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
4553 	if (ret < 0)
4554 		goto out;
4555 
4556 	while (1) {
4557 		eb = path->nodes[0];
4558 		slot = path->slots[0];
4559 		if (slot >= btrfs_header_nritems(eb)) {
4560 			ret = btrfs_next_leaf(root, path);
4561 			if (ret < 0) {
4562 				goto out;
4563 			} else if (ret > 0) {
4564 				ret = 0;
4565 				break;
4566 			}
4567 			continue;
4568 		}
4569 
4570 		btrfs_item_key_to_cpu(eb, &found_key, slot);
4571 		if (found_key.objectid != key.objectid ||
4572 		    found_key.type != key.type) {
4573 			ret = 0;
4574 			goto out;
4575 		}
4576 
4577 		ret = iterate_dir_item(root, path, &found_key,
4578 				       __process_new_xattr, sctx);
4579 		if (ret < 0)
4580 			goto out;
4581 
4582 		path->slots[0]++;
4583 	}
4584 
4585 out:
4586 	btrfs_free_path(path);
4587 	return ret;
4588 }
4589 
4590 static ssize_t fill_read_buf(struct send_ctx *sctx, u64 offset, u32 len)
4591 {
4592 	struct btrfs_root *root = sctx->send_root;
4593 	struct btrfs_fs_info *fs_info = root->fs_info;
4594 	struct inode *inode;
4595 	struct page *page;
4596 	char *addr;
4597 	struct btrfs_key key;
4598 	pgoff_t index = offset >> PAGE_SHIFT;
4599 	pgoff_t last_index;
4600 	unsigned pg_offset = offset & ~PAGE_MASK;
4601 	ssize_t ret = 0;
4602 
4603 	key.objectid = sctx->cur_ino;
4604 	key.type = BTRFS_INODE_ITEM_KEY;
4605 	key.offset = 0;
4606 
4607 	inode = btrfs_iget(fs_info->sb, &key, root, NULL);
4608 	if (IS_ERR(inode))
4609 		return PTR_ERR(inode);
4610 
4611 	if (offset + len > i_size_read(inode)) {
4612 		if (offset > i_size_read(inode))
4613 			len = 0;
4614 		else
4615 			len = offset - i_size_read(inode);
4616 	}
4617 	if (len == 0)
4618 		goto out;
4619 
4620 	last_index = (offset + len - 1) >> PAGE_SHIFT;
4621 
4622 	/* initial readahead */
4623 	memset(&sctx->ra, 0, sizeof(struct file_ra_state));
4624 	file_ra_state_init(&sctx->ra, inode->i_mapping);
4625 	btrfs_force_ra(inode->i_mapping, &sctx->ra, NULL, index,
4626 		       last_index - index + 1);
4627 
4628 	while (index <= last_index) {
4629 		unsigned cur_len = min_t(unsigned, len,
4630 					 PAGE_SIZE - pg_offset);
4631 		page = find_or_create_page(inode->i_mapping, index, GFP_KERNEL);
4632 		if (!page) {
4633 			ret = -ENOMEM;
4634 			break;
4635 		}
4636 
4637 		if (!PageUptodate(page)) {
4638 			btrfs_readpage(NULL, page);
4639 			lock_page(page);
4640 			if (!PageUptodate(page)) {
4641 				unlock_page(page);
4642 				put_page(page);
4643 				ret = -EIO;
4644 				break;
4645 			}
4646 		}
4647 
4648 		addr = kmap(page);
4649 		memcpy(sctx->read_buf + ret, addr + pg_offset, cur_len);
4650 		kunmap(page);
4651 		unlock_page(page);
4652 		put_page(page);
4653 		index++;
4654 		pg_offset = 0;
4655 		len -= cur_len;
4656 		ret += cur_len;
4657 	}
4658 out:
4659 	iput(inode);
4660 	return ret;
4661 }
4662 
4663 /*
4664  * Read some bytes from the current inode/file and send a write command to
4665  * user space.
4666  */
4667 static int send_write(struct send_ctx *sctx, u64 offset, u32 len)
4668 {
4669 	struct btrfs_fs_info *fs_info = sctx->send_root->fs_info;
4670 	int ret = 0;
4671 	struct fs_path *p;
4672 	ssize_t num_read = 0;
4673 
4674 	p = fs_path_alloc();
4675 	if (!p)
4676 		return -ENOMEM;
4677 
4678 	btrfs_debug(fs_info, "send_write offset=%llu, len=%d", offset, len);
4679 
4680 	num_read = fill_read_buf(sctx, offset, len);
4681 	if (num_read <= 0) {
4682 		if (num_read < 0)
4683 			ret = num_read;
4684 		goto out;
4685 	}
4686 
4687 	ret = begin_cmd(sctx, BTRFS_SEND_C_WRITE);
4688 	if (ret < 0)
4689 		goto out;
4690 
4691 	ret = get_cur_path(sctx, sctx->cur_ino, sctx->cur_inode_gen, p);
4692 	if (ret < 0)
4693 		goto out;
4694 
4695 	TLV_PUT_PATH(sctx, BTRFS_SEND_A_PATH, p);
4696 	TLV_PUT_U64(sctx, BTRFS_SEND_A_FILE_OFFSET, offset);
4697 	TLV_PUT(sctx, BTRFS_SEND_A_DATA, sctx->read_buf, num_read);
4698 
4699 	ret = send_cmd(sctx);
4700 
4701 tlv_put_failure:
4702 out:
4703 	fs_path_free(p);
4704 	if (ret < 0)
4705 		return ret;
4706 	return num_read;
4707 }
4708 
4709 /*
4710  * Send a clone command to user space.
4711  */
4712 static int send_clone(struct send_ctx *sctx,
4713 		      u64 offset, u32 len,
4714 		      struct clone_root *clone_root)
4715 {
4716 	int ret = 0;
4717 	struct fs_path *p;
4718 	u64 gen;
4719 
4720 	btrfs_debug(sctx->send_root->fs_info,
4721 		    "send_clone offset=%llu, len=%d, clone_root=%llu, clone_inode=%llu, clone_offset=%llu",
4722 		    offset, len, clone_root->root->objectid, clone_root->ino,
4723 		    clone_root->offset);
4724 
4725 	p = fs_path_alloc();
4726 	if (!p)
4727 		return -ENOMEM;
4728 
4729 	ret = begin_cmd(sctx, BTRFS_SEND_C_CLONE);
4730 	if (ret < 0)
4731 		goto out;
4732 
4733 	ret = get_cur_path(sctx, sctx->cur_ino, sctx->cur_inode_gen, p);
4734 	if (ret < 0)
4735 		goto out;
4736 
4737 	TLV_PUT_U64(sctx, BTRFS_SEND_A_FILE_OFFSET, offset);
4738 	TLV_PUT_U64(sctx, BTRFS_SEND_A_CLONE_LEN, len);
4739 	TLV_PUT_PATH(sctx, BTRFS_SEND_A_PATH, p);
4740 
4741 	if (clone_root->root == sctx->send_root) {
4742 		ret = get_inode_info(sctx->send_root, clone_root->ino, NULL,
4743 				&gen, NULL, NULL, NULL, NULL);
4744 		if (ret < 0)
4745 			goto out;
4746 		ret = get_cur_path(sctx, clone_root->ino, gen, p);
4747 	} else {
4748 		ret = get_inode_path(clone_root->root, clone_root->ino, p);
4749 	}
4750 	if (ret < 0)
4751 		goto out;
4752 
4753 	/*
4754 	 * If the parent we're using has a received_uuid set then use that as
4755 	 * our clone source as that is what we will look for when doing a
4756 	 * receive.
4757 	 *
4758 	 * This covers the case that we create a snapshot off of a received
4759 	 * subvolume and then use that as the parent and try to receive on a
4760 	 * different host.
4761 	 */
4762 	if (!btrfs_is_empty_uuid(clone_root->root->root_item.received_uuid))
4763 		TLV_PUT_UUID(sctx, BTRFS_SEND_A_CLONE_UUID,
4764 			     clone_root->root->root_item.received_uuid);
4765 	else
4766 		TLV_PUT_UUID(sctx, BTRFS_SEND_A_CLONE_UUID,
4767 			     clone_root->root->root_item.uuid);
4768 	TLV_PUT_U64(sctx, BTRFS_SEND_A_CLONE_CTRANSID,
4769 		    le64_to_cpu(clone_root->root->root_item.ctransid));
4770 	TLV_PUT_PATH(sctx, BTRFS_SEND_A_CLONE_PATH, p);
4771 	TLV_PUT_U64(sctx, BTRFS_SEND_A_CLONE_OFFSET,
4772 			clone_root->offset);
4773 
4774 	ret = send_cmd(sctx);
4775 
4776 tlv_put_failure:
4777 out:
4778 	fs_path_free(p);
4779 	return ret;
4780 }
4781 
4782 /*
4783  * Send an update extent command to user space.
4784  */
4785 static int send_update_extent(struct send_ctx *sctx,
4786 			      u64 offset, u32 len)
4787 {
4788 	int ret = 0;
4789 	struct fs_path *p;
4790 
4791 	p = fs_path_alloc();
4792 	if (!p)
4793 		return -ENOMEM;
4794 
4795 	ret = begin_cmd(sctx, BTRFS_SEND_C_UPDATE_EXTENT);
4796 	if (ret < 0)
4797 		goto out;
4798 
4799 	ret = get_cur_path(sctx, sctx->cur_ino, sctx->cur_inode_gen, p);
4800 	if (ret < 0)
4801 		goto out;
4802 
4803 	TLV_PUT_PATH(sctx, BTRFS_SEND_A_PATH, p);
4804 	TLV_PUT_U64(sctx, BTRFS_SEND_A_FILE_OFFSET, offset);
4805 	TLV_PUT_U64(sctx, BTRFS_SEND_A_SIZE, len);
4806 
4807 	ret = send_cmd(sctx);
4808 
4809 tlv_put_failure:
4810 out:
4811 	fs_path_free(p);
4812 	return ret;
4813 }
4814 
4815 static int send_hole(struct send_ctx *sctx, u64 end)
4816 {
4817 	struct fs_path *p = NULL;
4818 	u64 offset = sctx->cur_inode_last_extent;
4819 	u64 len;
4820 	int ret = 0;
4821 
4822 	p = fs_path_alloc();
4823 	if (!p)
4824 		return -ENOMEM;
4825 	ret = get_cur_path(sctx, sctx->cur_ino, sctx->cur_inode_gen, p);
4826 	if (ret < 0)
4827 		goto tlv_put_failure;
4828 	memset(sctx->read_buf, 0, BTRFS_SEND_READ_SIZE);
4829 	while (offset < end) {
4830 		len = min_t(u64, end - offset, BTRFS_SEND_READ_SIZE);
4831 
4832 		ret = begin_cmd(sctx, BTRFS_SEND_C_WRITE);
4833 		if (ret < 0)
4834 			break;
4835 		TLV_PUT_PATH(sctx, BTRFS_SEND_A_PATH, p);
4836 		TLV_PUT_U64(sctx, BTRFS_SEND_A_FILE_OFFSET, offset);
4837 		TLV_PUT(sctx, BTRFS_SEND_A_DATA, sctx->read_buf, len);
4838 		ret = send_cmd(sctx);
4839 		if (ret < 0)
4840 			break;
4841 		offset += len;
4842 	}
4843 tlv_put_failure:
4844 	fs_path_free(p);
4845 	return ret;
4846 }
4847 
4848 static int send_extent_data(struct send_ctx *sctx,
4849 			    const u64 offset,
4850 			    const u64 len)
4851 {
4852 	u64 sent = 0;
4853 
4854 	if (sctx->flags & BTRFS_SEND_FLAG_NO_FILE_DATA)
4855 		return send_update_extent(sctx, offset, len);
4856 
4857 	while (sent < len) {
4858 		u64 size = len - sent;
4859 		int ret;
4860 
4861 		if (size > BTRFS_SEND_READ_SIZE)
4862 			size = BTRFS_SEND_READ_SIZE;
4863 		ret = send_write(sctx, offset + sent, size);
4864 		if (ret < 0)
4865 			return ret;
4866 		if (!ret)
4867 			break;
4868 		sent += ret;
4869 	}
4870 	return 0;
4871 }
4872 
4873 static int clone_range(struct send_ctx *sctx,
4874 		       struct clone_root *clone_root,
4875 		       const u64 disk_byte,
4876 		       u64 data_offset,
4877 		       u64 offset,
4878 		       u64 len)
4879 {
4880 	struct btrfs_path *path;
4881 	struct btrfs_key key;
4882 	int ret;
4883 
4884 	path = alloc_path_for_send();
4885 	if (!path)
4886 		return -ENOMEM;
4887 
4888 	/*
4889 	 * We can't send a clone operation for the entire range if we find
4890 	 * extent items in the respective range in the source file that
4891 	 * refer to different extents or if we find holes.
4892 	 * So check for that and do a mix of clone and regular write/copy
4893 	 * operations if needed.
4894 	 *
4895 	 * Example:
4896 	 *
4897 	 * mkfs.btrfs -f /dev/sda
4898 	 * mount /dev/sda /mnt
4899 	 * xfs_io -f -c "pwrite -S 0xaa 0K 100K" /mnt/foo
4900 	 * cp --reflink=always /mnt/foo /mnt/bar
4901 	 * xfs_io -c "pwrite -S 0xbb 50K 50K" /mnt/foo
4902 	 * btrfs subvolume snapshot -r /mnt /mnt/snap
4903 	 *
4904 	 * If when we send the snapshot and we are processing file bar (which
4905 	 * has a higher inode number than foo) we blindly send a clone operation
4906 	 * for the [0, 100K[ range from foo to bar, the receiver ends up getting
4907 	 * a file bar that matches the content of file foo - iow, doesn't match
4908 	 * the content from bar in the original filesystem.
4909 	 */
4910 	key.objectid = clone_root->ino;
4911 	key.type = BTRFS_EXTENT_DATA_KEY;
4912 	key.offset = clone_root->offset;
4913 	ret = btrfs_search_slot(NULL, clone_root->root, &key, path, 0, 0);
4914 	if (ret < 0)
4915 		goto out;
4916 	if (ret > 0 && path->slots[0] > 0) {
4917 		btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0] - 1);
4918 		if (key.objectid == clone_root->ino &&
4919 		    key.type == BTRFS_EXTENT_DATA_KEY)
4920 			path->slots[0]--;
4921 	}
4922 
4923 	while (true) {
4924 		struct extent_buffer *leaf = path->nodes[0];
4925 		int slot = path->slots[0];
4926 		struct btrfs_file_extent_item *ei;
4927 		u8 type;
4928 		u64 ext_len;
4929 		u64 clone_len;
4930 
4931 		if (slot >= btrfs_header_nritems(leaf)) {
4932 			ret = btrfs_next_leaf(clone_root->root, path);
4933 			if (ret < 0)
4934 				goto out;
4935 			else if (ret > 0)
4936 				break;
4937 			continue;
4938 		}
4939 
4940 		btrfs_item_key_to_cpu(leaf, &key, slot);
4941 
4942 		/*
4943 		 * We might have an implicit trailing hole (NO_HOLES feature
4944 		 * enabled). We deal with it after leaving this loop.
4945 		 */
4946 		if (key.objectid != clone_root->ino ||
4947 		    key.type != BTRFS_EXTENT_DATA_KEY)
4948 			break;
4949 
4950 		ei = btrfs_item_ptr(leaf, slot, struct btrfs_file_extent_item);
4951 		type = btrfs_file_extent_type(leaf, ei);
4952 		if (type == BTRFS_FILE_EXTENT_INLINE) {
4953 			ext_len = btrfs_file_extent_inline_len(leaf, slot, ei);
4954 			ext_len = PAGE_ALIGN(ext_len);
4955 		} else {
4956 			ext_len = btrfs_file_extent_num_bytes(leaf, ei);
4957 		}
4958 
4959 		if (key.offset + ext_len <= clone_root->offset)
4960 			goto next;
4961 
4962 		if (key.offset > clone_root->offset) {
4963 			/* Implicit hole, NO_HOLES feature enabled. */
4964 			u64 hole_len = key.offset - clone_root->offset;
4965 
4966 			if (hole_len > len)
4967 				hole_len = len;
4968 			ret = send_extent_data(sctx, offset, hole_len);
4969 			if (ret < 0)
4970 				goto out;
4971 
4972 			len -= hole_len;
4973 			if (len == 0)
4974 				break;
4975 			offset += hole_len;
4976 			clone_root->offset += hole_len;
4977 			data_offset += hole_len;
4978 		}
4979 
4980 		if (key.offset >= clone_root->offset + len)
4981 			break;
4982 
4983 		clone_len = min_t(u64, ext_len, len);
4984 
4985 		if (btrfs_file_extent_disk_bytenr(leaf, ei) == disk_byte &&
4986 		    btrfs_file_extent_offset(leaf, ei) == data_offset)
4987 			ret = send_clone(sctx, offset, clone_len, clone_root);
4988 		else
4989 			ret = send_extent_data(sctx, offset, clone_len);
4990 
4991 		if (ret < 0)
4992 			goto out;
4993 
4994 		len -= clone_len;
4995 		if (len == 0)
4996 			break;
4997 		offset += clone_len;
4998 		clone_root->offset += clone_len;
4999 		data_offset += clone_len;
5000 next:
5001 		path->slots[0]++;
5002 	}
5003 
5004 	if (len > 0)
5005 		ret = send_extent_data(sctx, offset, len);
5006 	else
5007 		ret = 0;
5008 out:
5009 	btrfs_free_path(path);
5010 	return ret;
5011 }
5012 
5013 static int send_write_or_clone(struct send_ctx *sctx,
5014 			       struct btrfs_path *path,
5015 			       struct btrfs_key *key,
5016 			       struct clone_root *clone_root)
5017 {
5018 	int ret = 0;
5019 	struct btrfs_file_extent_item *ei;
5020 	u64 offset = key->offset;
5021 	u64 len;
5022 	u8 type;
5023 	u64 bs = sctx->send_root->fs_info->sb->s_blocksize;
5024 
5025 	ei = btrfs_item_ptr(path->nodes[0], path->slots[0],
5026 			struct btrfs_file_extent_item);
5027 	type = btrfs_file_extent_type(path->nodes[0], ei);
5028 	if (type == BTRFS_FILE_EXTENT_INLINE) {
5029 		len = btrfs_file_extent_inline_len(path->nodes[0],
5030 						   path->slots[0], ei);
5031 		/*
5032 		 * it is possible the inline item won't cover the whole page,
5033 		 * but there may be items after this page.  Make
5034 		 * sure to send the whole thing
5035 		 */
5036 		len = PAGE_ALIGN(len);
5037 	} else {
5038 		len = btrfs_file_extent_num_bytes(path->nodes[0], ei);
5039 	}
5040 
5041 	if (offset + len > sctx->cur_inode_size)
5042 		len = sctx->cur_inode_size - offset;
5043 	if (len == 0) {
5044 		ret = 0;
5045 		goto out;
5046 	}
5047 
5048 	if (clone_root && IS_ALIGNED(offset + len, bs)) {
5049 		u64 disk_byte;
5050 		u64 data_offset;
5051 
5052 		disk_byte = btrfs_file_extent_disk_bytenr(path->nodes[0], ei);
5053 		data_offset = btrfs_file_extent_offset(path->nodes[0], ei);
5054 		ret = clone_range(sctx, clone_root, disk_byte, data_offset,
5055 				  offset, len);
5056 	} else {
5057 		ret = send_extent_data(sctx, offset, len);
5058 	}
5059 out:
5060 	return ret;
5061 }
5062 
5063 static int is_extent_unchanged(struct send_ctx *sctx,
5064 			       struct btrfs_path *left_path,
5065 			       struct btrfs_key *ekey)
5066 {
5067 	int ret = 0;
5068 	struct btrfs_key key;
5069 	struct btrfs_path *path = NULL;
5070 	struct extent_buffer *eb;
5071 	int slot;
5072 	struct btrfs_key found_key;
5073 	struct btrfs_file_extent_item *ei;
5074 	u64 left_disknr;
5075 	u64 right_disknr;
5076 	u64 left_offset;
5077 	u64 right_offset;
5078 	u64 left_offset_fixed;
5079 	u64 left_len;
5080 	u64 right_len;
5081 	u64 left_gen;
5082 	u64 right_gen;
5083 	u8 left_type;
5084 	u8 right_type;
5085 
5086 	path = alloc_path_for_send();
5087 	if (!path)
5088 		return -ENOMEM;
5089 
5090 	eb = left_path->nodes[0];
5091 	slot = left_path->slots[0];
5092 	ei = btrfs_item_ptr(eb, slot, struct btrfs_file_extent_item);
5093 	left_type = btrfs_file_extent_type(eb, ei);
5094 
5095 	if (left_type != BTRFS_FILE_EXTENT_REG) {
5096 		ret = 0;
5097 		goto out;
5098 	}
5099 	left_disknr = btrfs_file_extent_disk_bytenr(eb, ei);
5100 	left_len = btrfs_file_extent_num_bytes(eb, ei);
5101 	left_offset = btrfs_file_extent_offset(eb, ei);
5102 	left_gen = btrfs_file_extent_generation(eb, ei);
5103 
5104 	/*
5105 	 * Following comments will refer to these graphics. L is the left
5106 	 * extents which we are checking at the moment. 1-8 are the right
5107 	 * extents that we iterate.
5108 	 *
5109 	 *       |-----L-----|
5110 	 * |-1-|-2a-|-3-|-4-|-5-|-6-|
5111 	 *
5112 	 *       |-----L-----|
5113 	 * |--1--|-2b-|...(same as above)
5114 	 *
5115 	 * Alternative situation. Happens on files where extents got split.
5116 	 *       |-----L-----|
5117 	 * |-----------7-----------|-6-|
5118 	 *
5119 	 * Alternative situation. Happens on files which got larger.
5120 	 *       |-----L-----|
5121 	 * |-8-|
5122 	 * Nothing follows after 8.
5123 	 */
5124 
5125 	key.objectid = ekey->objectid;
5126 	key.type = BTRFS_EXTENT_DATA_KEY;
5127 	key.offset = ekey->offset;
5128 	ret = btrfs_search_slot_for_read(sctx->parent_root, &key, path, 0, 0);
5129 	if (ret < 0)
5130 		goto out;
5131 	if (ret) {
5132 		ret = 0;
5133 		goto out;
5134 	}
5135 
5136 	/*
5137 	 * Handle special case where the right side has no extents at all.
5138 	 */
5139 	eb = path->nodes[0];
5140 	slot = path->slots[0];
5141 	btrfs_item_key_to_cpu(eb, &found_key, slot);
5142 	if (found_key.objectid != key.objectid ||
5143 	    found_key.type != key.type) {
5144 		/* If we're a hole then just pretend nothing changed */
5145 		ret = (left_disknr) ? 0 : 1;
5146 		goto out;
5147 	}
5148 
5149 	/*
5150 	 * We're now on 2a, 2b or 7.
5151 	 */
5152 	key = found_key;
5153 	while (key.offset < ekey->offset + left_len) {
5154 		ei = btrfs_item_ptr(eb, slot, struct btrfs_file_extent_item);
5155 		right_type = btrfs_file_extent_type(eb, ei);
5156 		if (right_type != BTRFS_FILE_EXTENT_REG) {
5157 			ret = 0;
5158 			goto out;
5159 		}
5160 
5161 		right_disknr = btrfs_file_extent_disk_bytenr(eb, ei);
5162 		right_len = btrfs_file_extent_num_bytes(eb, ei);
5163 		right_offset = btrfs_file_extent_offset(eb, ei);
5164 		right_gen = btrfs_file_extent_generation(eb, ei);
5165 
5166 		/*
5167 		 * Are we at extent 8? If yes, we know the extent is changed.
5168 		 * This may only happen on the first iteration.
5169 		 */
5170 		if (found_key.offset + right_len <= ekey->offset) {
5171 			/* If we're a hole just pretend nothing changed */
5172 			ret = (left_disknr) ? 0 : 1;
5173 			goto out;
5174 		}
5175 
5176 		left_offset_fixed = left_offset;
5177 		if (key.offset < ekey->offset) {
5178 			/* Fix the right offset for 2a and 7. */
5179 			right_offset += ekey->offset - key.offset;
5180 		} else {
5181 			/* Fix the left offset for all behind 2a and 2b */
5182 			left_offset_fixed += key.offset - ekey->offset;
5183 		}
5184 
5185 		/*
5186 		 * Check if we have the same extent.
5187 		 */
5188 		if (left_disknr != right_disknr ||
5189 		    left_offset_fixed != right_offset ||
5190 		    left_gen != right_gen) {
5191 			ret = 0;
5192 			goto out;
5193 		}
5194 
5195 		/*
5196 		 * Go to the next extent.
5197 		 */
5198 		ret = btrfs_next_item(sctx->parent_root, path);
5199 		if (ret < 0)
5200 			goto out;
5201 		if (!ret) {
5202 			eb = path->nodes[0];
5203 			slot = path->slots[0];
5204 			btrfs_item_key_to_cpu(eb, &found_key, slot);
5205 		}
5206 		if (ret || found_key.objectid != key.objectid ||
5207 		    found_key.type != key.type) {
5208 			key.offset += right_len;
5209 			break;
5210 		}
5211 		if (found_key.offset != key.offset + right_len) {
5212 			ret = 0;
5213 			goto out;
5214 		}
5215 		key = found_key;
5216 	}
5217 
5218 	/*
5219 	 * We're now behind the left extent (treat as unchanged) or at the end
5220 	 * of the right side (treat as changed).
5221 	 */
5222 	if (key.offset >= ekey->offset + left_len)
5223 		ret = 1;
5224 	else
5225 		ret = 0;
5226 
5227 
5228 out:
5229 	btrfs_free_path(path);
5230 	return ret;
5231 }
5232 
5233 static int get_last_extent(struct send_ctx *sctx, u64 offset)
5234 {
5235 	struct btrfs_path *path;
5236 	struct btrfs_root *root = sctx->send_root;
5237 	struct btrfs_file_extent_item *fi;
5238 	struct btrfs_key key;
5239 	u64 extent_end;
5240 	u8 type;
5241 	int ret;
5242 
5243 	path = alloc_path_for_send();
5244 	if (!path)
5245 		return -ENOMEM;
5246 
5247 	sctx->cur_inode_last_extent = 0;
5248 
5249 	key.objectid = sctx->cur_ino;
5250 	key.type = BTRFS_EXTENT_DATA_KEY;
5251 	key.offset = offset;
5252 	ret = btrfs_search_slot_for_read(root, &key, path, 0, 1);
5253 	if (ret < 0)
5254 		goto out;
5255 	ret = 0;
5256 	btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
5257 	if (key.objectid != sctx->cur_ino || key.type != BTRFS_EXTENT_DATA_KEY)
5258 		goto out;
5259 
5260 	fi = btrfs_item_ptr(path->nodes[0], path->slots[0],
5261 			    struct btrfs_file_extent_item);
5262 	type = btrfs_file_extent_type(path->nodes[0], fi);
5263 	if (type == BTRFS_FILE_EXTENT_INLINE) {
5264 		u64 size = btrfs_file_extent_inline_len(path->nodes[0],
5265 							path->slots[0], fi);
5266 		extent_end = ALIGN(key.offset + size,
5267 				   sctx->send_root->sectorsize);
5268 	} else {
5269 		extent_end = key.offset +
5270 			btrfs_file_extent_num_bytes(path->nodes[0], fi);
5271 	}
5272 	sctx->cur_inode_last_extent = extent_end;
5273 out:
5274 	btrfs_free_path(path);
5275 	return ret;
5276 }
5277 
5278 static int maybe_send_hole(struct send_ctx *sctx, struct btrfs_path *path,
5279 			   struct btrfs_key *key)
5280 {
5281 	struct btrfs_file_extent_item *fi;
5282 	u64 extent_end;
5283 	u8 type;
5284 	int ret = 0;
5285 
5286 	if (sctx->cur_ino != key->objectid || !need_send_hole(sctx))
5287 		return 0;
5288 
5289 	if (sctx->cur_inode_last_extent == (u64)-1) {
5290 		ret = get_last_extent(sctx, key->offset - 1);
5291 		if (ret)
5292 			return ret;
5293 	}
5294 
5295 	fi = btrfs_item_ptr(path->nodes[0], path->slots[0],
5296 			    struct btrfs_file_extent_item);
5297 	type = btrfs_file_extent_type(path->nodes[0], fi);
5298 	if (type == BTRFS_FILE_EXTENT_INLINE) {
5299 		u64 size = btrfs_file_extent_inline_len(path->nodes[0],
5300 							path->slots[0], fi);
5301 		extent_end = ALIGN(key->offset + size,
5302 				   sctx->send_root->sectorsize);
5303 	} else {
5304 		extent_end = key->offset +
5305 			btrfs_file_extent_num_bytes(path->nodes[0], fi);
5306 	}
5307 
5308 	if (path->slots[0] == 0 &&
5309 	    sctx->cur_inode_last_extent < key->offset) {
5310 		/*
5311 		 * We might have skipped entire leafs that contained only
5312 		 * file extent items for our current inode. These leafs have
5313 		 * a generation number smaller (older) than the one in the
5314 		 * current leaf and the leaf our last extent came from, and
5315 		 * are located between these 2 leafs.
5316 		 */
5317 		ret = get_last_extent(sctx, key->offset - 1);
5318 		if (ret)
5319 			return ret;
5320 	}
5321 
5322 	if (sctx->cur_inode_last_extent < key->offset)
5323 		ret = send_hole(sctx, key->offset);
5324 	sctx->cur_inode_last_extent = extent_end;
5325 	return ret;
5326 }
5327 
5328 static int process_extent(struct send_ctx *sctx,
5329 			  struct btrfs_path *path,
5330 			  struct btrfs_key *key)
5331 {
5332 	struct clone_root *found_clone = NULL;
5333 	int ret = 0;
5334 
5335 	if (S_ISLNK(sctx->cur_inode_mode))
5336 		return 0;
5337 
5338 	if (sctx->parent_root && !sctx->cur_inode_new) {
5339 		ret = is_extent_unchanged(sctx, path, key);
5340 		if (ret < 0)
5341 			goto out;
5342 		if (ret) {
5343 			ret = 0;
5344 			goto out_hole;
5345 		}
5346 	} else {
5347 		struct btrfs_file_extent_item *ei;
5348 		u8 type;
5349 
5350 		ei = btrfs_item_ptr(path->nodes[0], path->slots[0],
5351 				    struct btrfs_file_extent_item);
5352 		type = btrfs_file_extent_type(path->nodes[0], ei);
5353 		if (type == BTRFS_FILE_EXTENT_PREALLOC ||
5354 		    type == BTRFS_FILE_EXTENT_REG) {
5355 			/*
5356 			 * The send spec does not have a prealloc command yet,
5357 			 * so just leave a hole for prealloc'ed extents until
5358 			 * we have enough commands queued up to justify rev'ing
5359 			 * the send spec.
5360 			 */
5361 			if (type == BTRFS_FILE_EXTENT_PREALLOC) {
5362 				ret = 0;
5363 				goto out;
5364 			}
5365 
5366 			/* Have a hole, just skip it. */
5367 			if (btrfs_file_extent_disk_bytenr(path->nodes[0], ei) == 0) {
5368 				ret = 0;
5369 				goto out;
5370 			}
5371 		}
5372 	}
5373 
5374 	ret = find_extent_clone(sctx, path, key->objectid, key->offset,
5375 			sctx->cur_inode_size, &found_clone);
5376 	if (ret != -ENOENT && ret < 0)
5377 		goto out;
5378 
5379 	ret = send_write_or_clone(sctx, path, key, found_clone);
5380 	if (ret)
5381 		goto out;
5382 out_hole:
5383 	ret = maybe_send_hole(sctx, path, key);
5384 out:
5385 	return ret;
5386 }
5387 
5388 static int process_all_extents(struct send_ctx *sctx)
5389 {
5390 	int ret;
5391 	struct btrfs_root *root;
5392 	struct btrfs_path *path;
5393 	struct btrfs_key key;
5394 	struct btrfs_key found_key;
5395 	struct extent_buffer *eb;
5396 	int slot;
5397 
5398 	root = sctx->send_root;
5399 	path = alloc_path_for_send();
5400 	if (!path)
5401 		return -ENOMEM;
5402 
5403 	key.objectid = sctx->cmp_key->objectid;
5404 	key.type = BTRFS_EXTENT_DATA_KEY;
5405 	key.offset = 0;
5406 	ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
5407 	if (ret < 0)
5408 		goto out;
5409 
5410 	while (1) {
5411 		eb = path->nodes[0];
5412 		slot = path->slots[0];
5413 
5414 		if (slot >= btrfs_header_nritems(eb)) {
5415 			ret = btrfs_next_leaf(root, path);
5416 			if (ret < 0) {
5417 				goto out;
5418 			} else if (ret > 0) {
5419 				ret = 0;
5420 				break;
5421 			}
5422 			continue;
5423 		}
5424 
5425 		btrfs_item_key_to_cpu(eb, &found_key, slot);
5426 
5427 		if (found_key.objectid != key.objectid ||
5428 		    found_key.type != key.type) {
5429 			ret = 0;
5430 			goto out;
5431 		}
5432 
5433 		ret = process_extent(sctx, path, &found_key);
5434 		if (ret < 0)
5435 			goto out;
5436 
5437 		path->slots[0]++;
5438 	}
5439 
5440 out:
5441 	btrfs_free_path(path);
5442 	return ret;
5443 }
5444 
5445 static int process_recorded_refs_if_needed(struct send_ctx *sctx, int at_end,
5446 					   int *pending_move,
5447 					   int *refs_processed)
5448 {
5449 	int ret = 0;
5450 
5451 	if (sctx->cur_ino == 0)
5452 		goto out;
5453 	if (!at_end && sctx->cur_ino == sctx->cmp_key->objectid &&
5454 	    sctx->cmp_key->type <= BTRFS_INODE_EXTREF_KEY)
5455 		goto out;
5456 	if (list_empty(&sctx->new_refs) && list_empty(&sctx->deleted_refs))
5457 		goto out;
5458 
5459 	ret = process_recorded_refs(sctx, pending_move);
5460 	if (ret < 0)
5461 		goto out;
5462 
5463 	*refs_processed = 1;
5464 out:
5465 	return ret;
5466 }
5467 
5468 static int finish_inode_if_needed(struct send_ctx *sctx, int at_end)
5469 {
5470 	int ret = 0;
5471 	u64 left_mode;
5472 	u64 left_uid;
5473 	u64 left_gid;
5474 	u64 right_mode;
5475 	u64 right_uid;
5476 	u64 right_gid;
5477 	int need_chmod = 0;
5478 	int need_chown = 0;
5479 	int pending_move = 0;
5480 	int refs_processed = 0;
5481 
5482 	ret = process_recorded_refs_if_needed(sctx, at_end, &pending_move,
5483 					      &refs_processed);
5484 	if (ret < 0)
5485 		goto out;
5486 
5487 	/*
5488 	 * We have processed the refs and thus need to advance send_progress.
5489 	 * Now, calls to get_cur_xxx will take the updated refs of the current
5490 	 * inode into account.
5491 	 *
5492 	 * On the other hand, if our current inode is a directory and couldn't
5493 	 * be moved/renamed because its parent was renamed/moved too and it has
5494 	 * a higher inode number, we can only move/rename our current inode
5495 	 * after we moved/renamed its parent. Therefore in this case operate on
5496 	 * the old path (pre move/rename) of our current inode, and the
5497 	 * move/rename will be performed later.
5498 	 */
5499 	if (refs_processed && !pending_move)
5500 		sctx->send_progress = sctx->cur_ino + 1;
5501 
5502 	if (sctx->cur_ino == 0 || sctx->cur_inode_deleted)
5503 		goto out;
5504 	if (!at_end && sctx->cmp_key->objectid == sctx->cur_ino)
5505 		goto out;
5506 
5507 	ret = get_inode_info(sctx->send_root, sctx->cur_ino, NULL, NULL,
5508 			&left_mode, &left_uid, &left_gid, NULL);
5509 	if (ret < 0)
5510 		goto out;
5511 
5512 	if (!sctx->parent_root || sctx->cur_inode_new) {
5513 		need_chown = 1;
5514 		if (!S_ISLNK(sctx->cur_inode_mode))
5515 			need_chmod = 1;
5516 	} else {
5517 		ret = get_inode_info(sctx->parent_root, sctx->cur_ino,
5518 				NULL, NULL, &right_mode, &right_uid,
5519 				&right_gid, NULL);
5520 		if (ret < 0)
5521 			goto out;
5522 
5523 		if (left_uid != right_uid || left_gid != right_gid)
5524 			need_chown = 1;
5525 		if (!S_ISLNK(sctx->cur_inode_mode) && left_mode != right_mode)
5526 			need_chmod = 1;
5527 	}
5528 
5529 	if (S_ISREG(sctx->cur_inode_mode)) {
5530 		if (need_send_hole(sctx)) {
5531 			if (sctx->cur_inode_last_extent == (u64)-1 ||
5532 			    sctx->cur_inode_last_extent <
5533 			    sctx->cur_inode_size) {
5534 				ret = get_last_extent(sctx, (u64)-1);
5535 				if (ret)
5536 					goto out;
5537 			}
5538 			if (sctx->cur_inode_last_extent <
5539 			    sctx->cur_inode_size) {
5540 				ret = send_hole(sctx, sctx->cur_inode_size);
5541 				if (ret)
5542 					goto out;
5543 			}
5544 		}
5545 		ret = send_truncate(sctx, sctx->cur_ino, sctx->cur_inode_gen,
5546 				sctx->cur_inode_size);
5547 		if (ret < 0)
5548 			goto out;
5549 	}
5550 
5551 	if (need_chown) {
5552 		ret = send_chown(sctx, sctx->cur_ino, sctx->cur_inode_gen,
5553 				left_uid, left_gid);
5554 		if (ret < 0)
5555 			goto out;
5556 	}
5557 	if (need_chmod) {
5558 		ret = send_chmod(sctx, sctx->cur_ino, sctx->cur_inode_gen,
5559 				left_mode);
5560 		if (ret < 0)
5561 			goto out;
5562 	}
5563 
5564 	/*
5565 	 * If other directory inodes depended on our current directory
5566 	 * inode's move/rename, now do their move/rename operations.
5567 	 */
5568 	if (!is_waiting_for_move(sctx, sctx->cur_ino)) {
5569 		ret = apply_children_dir_moves(sctx);
5570 		if (ret)
5571 			goto out;
5572 		/*
5573 		 * Need to send that every time, no matter if it actually
5574 		 * changed between the two trees as we have done changes to
5575 		 * the inode before. If our inode is a directory and it's
5576 		 * waiting to be moved/renamed, we will send its utimes when
5577 		 * it's moved/renamed, therefore we don't need to do it here.
5578 		 */
5579 		sctx->send_progress = sctx->cur_ino + 1;
5580 		ret = send_utimes(sctx, sctx->cur_ino, sctx->cur_inode_gen);
5581 		if (ret < 0)
5582 			goto out;
5583 	}
5584 
5585 out:
5586 	return ret;
5587 }
5588 
5589 static int changed_inode(struct send_ctx *sctx,
5590 			 enum btrfs_compare_tree_result result)
5591 {
5592 	int ret = 0;
5593 	struct btrfs_key *key = sctx->cmp_key;
5594 	struct btrfs_inode_item *left_ii = NULL;
5595 	struct btrfs_inode_item *right_ii = NULL;
5596 	u64 left_gen = 0;
5597 	u64 right_gen = 0;
5598 
5599 	sctx->cur_ino = key->objectid;
5600 	sctx->cur_inode_new_gen = 0;
5601 	sctx->cur_inode_last_extent = (u64)-1;
5602 
5603 	/*
5604 	 * Set send_progress to current inode. This will tell all get_cur_xxx
5605 	 * functions that the current inode's refs are not updated yet. Later,
5606 	 * when process_recorded_refs is finished, it is set to cur_ino + 1.
5607 	 */
5608 	sctx->send_progress = sctx->cur_ino;
5609 
5610 	if (result == BTRFS_COMPARE_TREE_NEW ||
5611 	    result == BTRFS_COMPARE_TREE_CHANGED) {
5612 		left_ii = btrfs_item_ptr(sctx->left_path->nodes[0],
5613 				sctx->left_path->slots[0],
5614 				struct btrfs_inode_item);
5615 		left_gen = btrfs_inode_generation(sctx->left_path->nodes[0],
5616 				left_ii);
5617 	} else {
5618 		right_ii = btrfs_item_ptr(sctx->right_path->nodes[0],
5619 				sctx->right_path->slots[0],
5620 				struct btrfs_inode_item);
5621 		right_gen = btrfs_inode_generation(sctx->right_path->nodes[0],
5622 				right_ii);
5623 	}
5624 	if (result == BTRFS_COMPARE_TREE_CHANGED) {
5625 		right_ii = btrfs_item_ptr(sctx->right_path->nodes[0],
5626 				sctx->right_path->slots[0],
5627 				struct btrfs_inode_item);
5628 
5629 		right_gen = btrfs_inode_generation(sctx->right_path->nodes[0],
5630 				right_ii);
5631 
5632 		/*
5633 		 * The cur_ino = root dir case is special here. We can't treat
5634 		 * the inode as deleted+reused because it would generate a
5635 		 * stream that tries to delete/mkdir the root dir.
5636 		 */
5637 		if (left_gen != right_gen &&
5638 		    sctx->cur_ino != BTRFS_FIRST_FREE_OBJECTID)
5639 			sctx->cur_inode_new_gen = 1;
5640 	}
5641 
5642 	if (result == BTRFS_COMPARE_TREE_NEW) {
5643 		sctx->cur_inode_gen = left_gen;
5644 		sctx->cur_inode_new = 1;
5645 		sctx->cur_inode_deleted = 0;
5646 		sctx->cur_inode_size = btrfs_inode_size(
5647 				sctx->left_path->nodes[0], left_ii);
5648 		sctx->cur_inode_mode = btrfs_inode_mode(
5649 				sctx->left_path->nodes[0], left_ii);
5650 		sctx->cur_inode_rdev = btrfs_inode_rdev(
5651 				sctx->left_path->nodes[0], left_ii);
5652 		if (sctx->cur_ino != BTRFS_FIRST_FREE_OBJECTID)
5653 			ret = send_create_inode_if_needed(sctx);
5654 	} else if (result == BTRFS_COMPARE_TREE_DELETED) {
5655 		sctx->cur_inode_gen = right_gen;
5656 		sctx->cur_inode_new = 0;
5657 		sctx->cur_inode_deleted = 1;
5658 		sctx->cur_inode_size = btrfs_inode_size(
5659 				sctx->right_path->nodes[0], right_ii);
5660 		sctx->cur_inode_mode = btrfs_inode_mode(
5661 				sctx->right_path->nodes[0], right_ii);
5662 	} else if (result == BTRFS_COMPARE_TREE_CHANGED) {
5663 		/*
5664 		 * We need to do some special handling in case the inode was
5665 		 * reported as changed with a changed generation number. This
5666 		 * means that the original inode was deleted and new inode
5667 		 * reused the same inum. So we have to treat the old inode as
5668 		 * deleted and the new one as new.
5669 		 */
5670 		if (sctx->cur_inode_new_gen) {
5671 			/*
5672 			 * First, process the inode as if it was deleted.
5673 			 */
5674 			sctx->cur_inode_gen = right_gen;
5675 			sctx->cur_inode_new = 0;
5676 			sctx->cur_inode_deleted = 1;
5677 			sctx->cur_inode_size = btrfs_inode_size(
5678 					sctx->right_path->nodes[0], right_ii);
5679 			sctx->cur_inode_mode = btrfs_inode_mode(
5680 					sctx->right_path->nodes[0], right_ii);
5681 			ret = process_all_refs(sctx,
5682 					BTRFS_COMPARE_TREE_DELETED);
5683 			if (ret < 0)
5684 				goto out;
5685 
5686 			/*
5687 			 * Now process the inode as if it was new.
5688 			 */
5689 			sctx->cur_inode_gen = left_gen;
5690 			sctx->cur_inode_new = 1;
5691 			sctx->cur_inode_deleted = 0;
5692 			sctx->cur_inode_size = btrfs_inode_size(
5693 					sctx->left_path->nodes[0], left_ii);
5694 			sctx->cur_inode_mode = btrfs_inode_mode(
5695 					sctx->left_path->nodes[0], left_ii);
5696 			sctx->cur_inode_rdev = btrfs_inode_rdev(
5697 					sctx->left_path->nodes[0], left_ii);
5698 			ret = send_create_inode_if_needed(sctx);
5699 			if (ret < 0)
5700 				goto out;
5701 
5702 			ret = process_all_refs(sctx, BTRFS_COMPARE_TREE_NEW);
5703 			if (ret < 0)
5704 				goto out;
5705 			/*
5706 			 * Advance send_progress now as we did not get into
5707 			 * process_recorded_refs_if_needed in the new_gen case.
5708 			 */
5709 			sctx->send_progress = sctx->cur_ino + 1;
5710 
5711 			/*
5712 			 * Now process all extents and xattrs of the inode as if
5713 			 * they were all new.
5714 			 */
5715 			ret = process_all_extents(sctx);
5716 			if (ret < 0)
5717 				goto out;
5718 			ret = process_all_new_xattrs(sctx);
5719 			if (ret < 0)
5720 				goto out;
5721 		} else {
5722 			sctx->cur_inode_gen = left_gen;
5723 			sctx->cur_inode_new = 0;
5724 			sctx->cur_inode_new_gen = 0;
5725 			sctx->cur_inode_deleted = 0;
5726 			sctx->cur_inode_size = btrfs_inode_size(
5727 					sctx->left_path->nodes[0], left_ii);
5728 			sctx->cur_inode_mode = btrfs_inode_mode(
5729 					sctx->left_path->nodes[0], left_ii);
5730 		}
5731 	}
5732 
5733 out:
5734 	return ret;
5735 }
5736 
5737 /*
5738  * We have to process new refs before deleted refs, but compare_trees gives us
5739  * the new and deleted refs mixed. To fix this, we record the new/deleted refs
5740  * first and later process them in process_recorded_refs.
5741  * For the cur_inode_new_gen case, we skip recording completely because
5742  * changed_inode did already initiate processing of refs. The reason for this is
5743  * that in this case, compare_tree actually compares the refs of 2 different
5744  * inodes. To fix this, process_all_refs is used in changed_inode to handle all
5745  * refs of the right tree as deleted and all refs of the left tree as new.
5746  */
5747 static int changed_ref(struct send_ctx *sctx,
5748 		       enum btrfs_compare_tree_result result)
5749 {
5750 	int ret = 0;
5751 
5752 	if (sctx->cur_ino != sctx->cmp_key->objectid) {
5753 		inconsistent_snapshot_error(sctx, result, "reference");
5754 		return -EIO;
5755 	}
5756 
5757 	if (!sctx->cur_inode_new_gen &&
5758 	    sctx->cur_ino != BTRFS_FIRST_FREE_OBJECTID) {
5759 		if (result == BTRFS_COMPARE_TREE_NEW)
5760 			ret = record_new_ref(sctx);
5761 		else if (result == BTRFS_COMPARE_TREE_DELETED)
5762 			ret = record_deleted_ref(sctx);
5763 		else if (result == BTRFS_COMPARE_TREE_CHANGED)
5764 			ret = record_changed_ref(sctx);
5765 	}
5766 
5767 	return ret;
5768 }
5769 
5770 /*
5771  * Process new/deleted/changed xattrs. We skip processing in the
5772  * cur_inode_new_gen case because changed_inode did already initiate processing
5773  * of xattrs. The reason is the same as in changed_ref
5774  */
5775 static int changed_xattr(struct send_ctx *sctx,
5776 			 enum btrfs_compare_tree_result result)
5777 {
5778 	int ret = 0;
5779 
5780 	if (sctx->cur_ino != sctx->cmp_key->objectid) {
5781 		inconsistent_snapshot_error(sctx, result, "xattr");
5782 		return -EIO;
5783 	}
5784 
5785 	if (!sctx->cur_inode_new_gen && !sctx->cur_inode_deleted) {
5786 		if (result == BTRFS_COMPARE_TREE_NEW)
5787 			ret = process_new_xattr(sctx);
5788 		else if (result == BTRFS_COMPARE_TREE_DELETED)
5789 			ret = process_deleted_xattr(sctx);
5790 		else if (result == BTRFS_COMPARE_TREE_CHANGED)
5791 			ret = process_changed_xattr(sctx);
5792 	}
5793 
5794 	return ret;
5795 }
5796 
5797 /*
5798  * Process new/deleted/changed extents. We skip processing in the
5799  * cur_inode_new_gen case because changed_inode did already initiate processing
5800  * of extents. The reason is the same as in changed_ref
5801  */
5802 static int changed_extent(struct send_ctx *sctx,
5803 			  enum btrfs_compare_tree_result result)
5804 {
5805 	int ret = 0;
5806 
5807 	if (sctx->cur_ino != sctx->cmp_key->objectid) {
5808 		inconsistent_snapshot_error(sctx, result, "extent");
5809 		return -EIO;
5810 	}
5811 
5812 	if (!sctx->cur_inode_new_gen && !sctx->cur_inode_deleted) {
5813 		if (result != BTRFS_COMPARE_TREE_DELETED)
5814 			ret = process_extent(sctx, sctx->left_path,
5815 					sctx->cmp_key);
5816 	}
5817 
5818 	return ret;
5819 }
5820 
5821 static int dir_changed(struct send_ctx *sctx, u64 dir)
5822 {
5823 	u64 orig_gen, new_gen;
5824 	int ret;
5825 
5826 	ret = get_inode_info(sctx->send_root, dir, NULL, &new_gen, NULL, NULL,
5827 			     NULL, NULL);
5828 	if (ret)
5829 		return ret;
5830 
5831 	ret = get_inode_info(sctx->parent_root, dir, NULL, &orig_gen, NULL,
5832 			     NULL, NULL, NULL);
5833 	if (ret)
5834 		return ret;
5835 
5836 	return (orig_gen != new_gen) ? 1 : 0;
5837 }
5838 
5839 static int compare_refs(struct send_ctx *sctx, struct btrfs_path *path,
5840 			struct btrfs_key *key)
5841 {
5842 	struct btrfs_inode_extref *extref;
5843 	struct extent_buffer *leaf;
5844 	u64 dirid = 0, last_dirid = 0;
5845 	unsigned long ptr;
5846 	u32 item_size;
5847 	u32 cur_offset = 0;
5848 	int ref_name_len;
5849 	int ret = 0;
5850 
5851 	/* Easy case, just check this one dirid */
5852 	if (key->type == BTRFS_INODE_REF_KEY) {
5853 		dirid = key->offset;
5854 
5855 		ret = dir_changed(sctx, dirid);
5856 		goto out;
5857 	}
5858 
5859 	leaf = path->nodes[0];
5860 	item_size = btrfs_item_size_nr(leaf, path->slots[0]);
5861 	ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);
5862 	while (cur_offset < item_size) {
5863 		extref = (struct btrfs_inode_extref *)(ptr +
5864 						       cur_offset);
5865 		dirid = btrfs_inode_extref_parent(leaf, extref);
5866 		ref_name_len = btrfs_inode_extref_name_len(leaf, extref);
5867 		cur_offset += ref_name_len + sizeof(*extref);
5868 		if (dirid == last_dirid)
5869 			continue;
5870 		ret = dir_changed(sctx, dirid);
5871 		if (ret)
5872 			break;
5873 		last_dirid = dirid;
5874 	}
5875 out:
5876 	return ret;
5877 }
5878 
5879 /*
5880  * Updates compare related fields in sctx and simply forwards to the actual
5881  * changed_xxx functions.
5882  */
5883 static int changed_cb(struct btrfs_root *left_root,
5884 		      struct btrfs_root *right_root,
5885 		      struct btrfs_path *left_path,
5886 		      struct btrfs_path *right_path,
5887 		      struct btrfs_key *key,
5888 		      enum btrfs_compare_tree_result result,
5889 		      void *ctx)
5890 {
5891 	int ret = 0;
5892 	struct send_ctx *sctx = ctx;
5893 
5894 	if (result == BTRFS_COMPARE_TREE_SAME) {
5895 		if (key->type == BTRFS_INODE_REF_KEY ||
5896 		    key->type == BTRFS_INODE_EXTREF_KEY) {
5897 			ret = compare_refs(sctx, left_path, key);
5898 			if (!ret)
5899 				return 0;
5900 			if (ret < 0)
5901 				return ret;
5902 		} else if (key->type == BTRFS_EXTENT_DATA_KEY) {
5903 			return maybe_send_hole(sctx, left_path, key);
5904 		} else {
5905 			return 0;
5906 		}
5907 		result = BTRFS_COMPARE_TREE_CHANGED;
5908 		ret = 0;
5909 	}
5910 
5911 	sctx->left_path = left_path;
5912 	sctx->right_path = right_path;
5913 	sctx->cmp_key = key;
5914 
5915 	ret = finish_inode_if_needed(sctx, 0);
5916 	if (ret < 0)
5917 		goto out;
5918 
5919 	/* Ignore non-FS objects */
5920 	if (key->objectid == BTRFS_FREE_INO_OBJECTID ||
5921 	    key->objectid == BTRFS_FREE_SPACE_OBJECTID)
5922 		goto out;
5923 
5924 	if (key->type == BTRFS_INODE_ITEM_KEY)
5925 		ret = changed_inode(sctx, result);
5926 	else if (key->type == BTRFS_INODE_REF_KEY ||
5927 		 key->type == BTRFS_INODE_EXTREF_KEY)
5928 		ret = changed_ref(sctx, result);
5929 	else if (key->type == BTRFS_XATTR_ITEM_KEY)
5930 		ret = changed_xattr(sctx, result);
5931 	else if (key->type == BTRFS_EXTENT_DATA_KEY)
5932 		ret = changed_extent(sctx, result);
5933 
5934 out:
5935 	return ret;
5936 }
5937 
5938 static int full_send_tree(struct send_ctx *sctx)
5939 {
5940 	int ret;
5941 	struct btrfs_root *send_root = sctx->send_root;
5942 	struct btrfs_key key;
5943 	struct btrfs_key found_key;
5944 	struct btrfs_path *path;
5945 	struct extent_buffer *eb;
5946 	int slot;
5947 
5948 	path = alloc_path_for_send();
5949 	if (!path)
5950 		return -ENOMEM;
5951 
5952 	key.objectid = BTRFS_FIRST_FREE_OBJECTID;
5953 	key.type = BTRFS_INODE_ITEM_KEY;
5954 	key.offset = 0;
5955 
5956 	ret = btrfs_search_slot_for_read(send_root, &key, path, 1, 0);
5957 	if (ret < 0)
5958 		goto out;
5959 	if (ret)
5960 		goto out_finish;
5961 
5962 	while (1) {
5963 		eb = path->nodes[0];
5964 		slot = path->slots[0];
5965 		btrfs_item_key_to_cpu(eb, &found_key, slot);
5966 
5967 		ret = changed_cb(send_root, NULL, path, NULL,
5968 				&found_key, BTRFS_COMPARE_TREE_NEW, sctx);
5969 		if (ret < 0)
5970 			goto out;
5971 
5972 		key.objectid = found_key.objectid;
5973 		key.type = found_key.type;
5974 		key.offset = found_key.offset + 1;
5975 
5976 		ret = btrfs_next_item(send_root, path);
5977 		if (ret < 0)
5978 			goto out;
5979 		if (ret) {
5980 			ret  = 0;
5981 			break;
5982 		}
5983 	}
5984 
5985 out_finish:
5986 	ret = finish_inode_if_needed(sctx, 1);
5987 
5988 out:
5989 	btrfs_free_path(path);
5990 	return ret;
5991 }
5992 
5993 static int send_subvol(struct send_ctx *sctx)
5994 {
5995 	int ret;
5996 
5997 	if (!(sctx->flags & BTRFS_SEND_FLAG_OMIT_STREAM_HEADER)) {
5998 		ret = send_header(sctx);
5999 		if (ret < 0)
6000 			goto out;
6001 	}
6002 
6003 	ret = send_subvol_begin(sctx);
6004 	if (ret < 0)
6005 		goto out;
6006 
6007 	if (sctx->parent_root) {
6008 		ret = btrfs_compare_trees(sctx->send_root, sctx->parent_root,
6009 				changed_cb, sctx);
6010 		if (ret < 0)
6011 			goto out;
6012 		ret = finish_inode_if_needed(sctx, 1);
6013 		if (ret < 0)
6014 			goto out;
6015 	} else {
6016 		ret = full_send_tree(sctx);
6017 		if (ret < 0)
6018 			goto out;
6019 	}
6020 
6021 out:
6022 	free_recorded_refs(sctx);
6023 	return ret;
6024 }
6025 
6026 /*
6027  * If orphan cleanup did remove any orphans from a root, it means the tree
6028  * was modified and therefore the commit root is not the same as the current
6029  * root anymore. This is a problem, because send uses the commit root and
6030  * therefore can see inode items that don't exist in the current root anymore,
6031  * and for example make calls to btrfs_iget, which will do tree lookups based
6032  * on the current root and not on the commit root. Those lookups will fail,
6033  * returning a -ESTALE error, and making send fail with that error. So make
6034  * sure a send does not see any orphans we have just removed, and that it will
6035  * see the same inodes regardless of whether a transaction commit happened
6036  * before it started (meaning that the commit root will be the same as the
6037  * current root) or not.
6038  */
6039 static int ensure_commit_roots_uptodate(struct send_ctx *sctx)
6040 {
6041 	int i;
6042 	struct btrfs_trans_handle *trans = NULL;
6043 
6044 again:
6045 	if (sctx->parent_root &&
6046 	    sctx->parent_root->node != sctx->parent_root->commit_root)
6047 		goto commit_trans;
6048 
6049 	for (i = 0; i < sctx->clone_roots_cnt; i++)
6050 		if (sctx->clone_roots[i].root->node !=
6051 		    sctx->clone_roots[i].root->commit_root)
6052 			goto commit_trans;
6053 
6054 	if (trans)
6055 		return btrfs_end_transaction(trans, sctx->send_root);
6056 
6057 	return 0;
6058 
6059 commit_trans:
6060 	/* Use any root, all fs roots will get their commit roots updated. */
6061 	if (!trans) {
6062 		trans = btrfs_join_transaction(sctx->send_root);
6063 		if (IS_ERR(trans))
6064 			return PTR_ERR(trans);
6065 		goto again;
6066 	}
6067 
6068 	return btrfs_commit_transaction(trans, sctx->send_root);
6069 }
6070 
6071 static void btrfs_root_dec_send_in_progress(struct btrfs_root* root)
6072 {
6073 	spin_lock(&root->root_item_lock);
6074 	root->send_in_progress--;
6075 	/*
6076 	 * Not much left to do, we don't know why it's unbalanced and
6077 	 * can't blindly reset it to 0.
6078 	 */
6079 	if (root->send_in_progress < 0)
6080 		btrfs_err(root->fs_info,
6081 			"send_in_progres unbalanced %d root %llu",
6082 			root->send_in_progress, root->root_key.objectid);
6083 	spin_unlock(&root->root_item_lock);
6084 }
6085 
6086 long btrfs_ioctl_send(struct file *mnt_file, void __user *arg_)
6087 {
6088 	int ret = 0;
6089 	struct btrfs_root *send_root;
6090 	struct btrfs_root *clone_root;
6091 	struct btrfs_fs_info *fs_info;
6092 	struct btrfs_ioctl_send_args *arg = NULL;
6093 	struct btrfs_key key;
6094 	struct send_ctx *sctx = NULL;
6095 	u32 i;
6096 	u64 *clone_sources_tmp = NULL;
6097 	int clone_sources_to_rollback = 0;
6098 	unsigned alloc_size;
6099 	int sort_clone_roots = 0;
6100 	int index;
6101 
6102 	if (!capable(CAP_SYS_ADMIN))
6103 		return -EPERM;
6104 
6105 	send_root = BTRFS_I(file_inode(mnt_file))->root;
6106 	fs_info = send_root->fs_info;
6107 
6108 	/*
6109 	 * The subvolume must remain read-only during send, protect against
6110 	 * making it RW. This also protects against deletion.
6111 	 */
6112 	spin_lock(&send_root->root_item_lock);
6113 	send_root->send_in_progress++;
6114 	spin_unlock(&send_root->root_item_lock);
6115 
6116 	/*
6117 	 * This is done when we lookup the root, it should already be complete
6118 	 * by the time we get here.
6119 	 */
6120 	WARN_ON(send_root->orphan_cleanup_state != ORPHAN_CLEANUP_DONE);
6121 
6122 	/*
6123 	 * Userspace tools do the checks and warn the user if it's
6124 	 * not RO.
6125 	 */
6126 	if (!btrfs_root_readonly(send_root)) {
6127 		ret = -EPERM;
6128 		goto out;
6129 	}
6130 
6131 	arg = memdup_user(arg_, sizeof(*arg));
6132 	if (IS_ERR(arg)) {
6133 		ret = PTR_ERR(arg);
6134 		arg = NULL;
6135 		goto out;
6136 	}
6137 
6138 	if (arg->clone_sources_count >
6139 	    ULLONG_MAX / sizeof(*arg->clone_sources)) {
6140 		ret = -EINVAL;
6141 		goto out;
6142 	}
6143 
6144 	if (!access_ok(VERIFY_READ, arg->clone_sources,
6145 			sizeof(*arg->clone_sources) *
6146 			arg->clone_sources_count)) {
6147 		ret = -EFAULT;
6148 		goto out;
6149 	}
6150 
6151 	if (arg->flags & ~BTRFS_SEND_FLAG_MASK) {
6152 		ret = -EINVAL;
6153 		goto out;
6154 	}
6155 
6156 	sctx = kzalloc(sizeof(struct send_ctx), GFP_KERNEL);
6157 	if (!sctx) {
6158 		ret = -ENOMEM;
6159 		goto out;
6160 	}
6161 
6162 	INIT_LIST_HEAD(&sctx->new_refs);
6163 	INIT_LIST_HEAD(&sctx->deleted_refs);
6164 	INIT_RADIX_TREE(&sctx->name_cache, GFP_KERNEL);
6165 	INIT_LIST_HEAD(&sctx->name_cache_list);
6166 
6167 	sctx->flags = arg->flags;
6168 
6169 	sctx->send_filp = fget(arg->send_fd);
6170 	if (!sctx->send_filp) {
6171 		ret = -EBADF;
6172 		goto out;
6173 	}
6174 
6175 	sctx->send_root = send_root;
6176 	/*
6177 	 * Unlikely but possible, if the subvolume is marked for deletion but
6178 	 * is slow to remove the directory entry, send can still be started
6179 	 */
6180 	if (btrfs_root_dead(sctx->send_root)) {
6181 		ret = -EPERM;
6182 		goto out;
6183 	}
6184 
6185 	sctx->clone_roots_cnt = arg->clone_sources_count;
6186 
6187 	sctx->send_max_size = BTRFS_SEND_BUF_SIZE;
6188 	sctx->send_buf = kmalloc(sctx->send_max_size, GFP_KERNEL | __GFP_NOWARN);
6189 	if (!sctx->send_buf) {
6190 		sctx->send_buf = vmalloc(sctx->send_max_size);
6191 		if (!sctx->send_buf) {
6192 			ret = -ENOMEM;
6193 			goto out;
6194 		}
6195 	}
6196 
6197 	sctx->read_buf = kmalloc(BTRFS_SEND_READ_SIZE, GFP_KERNEL | __GFP_NOWARN);
6198 	if (!sctx->read_buf) {
6199 		sctx->read_buf = vmalloc(BTRFS_SEND_READ_SIZE);
6200 		if (!sctx->read_buf) {
6201 			ret = -ENOMEM;
6202 			goto out;
6203 		}
6204 	}
6205 
6206 	sctx->pending_dir_moves = RB_ROOT;
6207 	sctx->waiting_dir_moves = RB_ROOT;
6208 	sctx->orphan_dirs = RB_ROOT;
6209 
6210 	alloc_size = sizeof(struct clone_root) * (arg->clone_sources_count + 1);
6211 
6212 	sctx->clone_roots = kzalloc(alloc_size, GFP_KERNEL | __GFP_NOWARN);
6213 	if (!sctx->clone_roots) {
6214 		sctx->clone_roots = vzalloc(alloc_size);
6215 		if (!sctx->clone_roots) {
6216 			ret = -ENOMEM;
6217 			goto out;
6218 		}
6219 	}
6220 
6221 	alloc_size = arg->clone_sources_count * sizeof(*arg->clone_sources);
6222 
6223 	if (arg->clone_sources_count) {
6224 		clone_sources_tmp = kmalloc(alloc_size, GFP_KERNEL | __GFP_NOWARN);
6225 		if (!clone_sources_tmp) {
6226 			clone_sources_tmp = vmalloc(alloc_size);
6227 			if (!clone_sources_tmp) {
6228 				ret = -ENOMEM;
6229 				goto out;
6230 			}
6231 		}
6232 
6233 		ret = copy_from_user(clone_sources_tmp, arg->clone_sources,
6234 				alloc_size);
6235 		if (ret) {
6236 			ret = -EFAULT;
6237 			goto out;
6238 		}
6239 
6240 		for (i = 0; i < arg->clone_sources_count; i++) {
6241 			key.objectid = clone_sources_tmp[i];
6242 			key.type = BTRFS_ROOT_ITEM_KEY;
6243 			key.offset = (u64)-1;
6244 
6245 			index = srcu_read_lock(&fs_info->subvol_srcu);
6246 
6247 			clone_root = btrfs_read_fs_root_no_name(fs_info, &key);
6248 			if (IS_ERR(clone_root)) {
6249 				srcu_read_unlock(&fs_info->subvol_srcu, index);
6250 				ret = PTR_ERR(clone_root);
6251 				goto out;
6252 			}
6253 			spin_lock(&clone_root->root_item_lock);
6254 			if (!btrfs_root_readonly(clone_root) ||
6255 			    btrfs_root_dead(clone_root)) {
6256 				spin_unlock(&clone_root->root_item_lock);
6257 				srcu_read_unlock(&fs_info->subvol_srcu, index);
6258 				ret = -EPERM;
6259 				goto out;
6260 			}
6261 			clone_root->send_in_progress++;
6262 			spin_unlock(&clone_root->root_item_lock);
6263 			srcu_read_unlock(&fs_info->subvol_srcu, index);
6264 
6265 			sctx->clone_roots[i].root = clone_root;
6266 			clone_sources_to_rollback = i + 1;
6267 		}
6268 		kvfree(clone_sources_tmp);
6269 		clone_sources_tmp = NULL;
6270 	}
6271 
6272 	if (arg->parent_root) {
6273 		key.objectid = arg->parent_root;
6274 		key.type = BTRFS_ROOT_ITEM_KEY;
6275 		key.offset = (u64)-1;
6276 
6277 		index = srcu_read_lock(&fs_info->subvol_srcu);
6278 
6279 		sctx->parent_root = btrfs_read_fs_root_no_name(fs_info, &key);
6280 		if (IS_ERR(sctx->parent_root)) {
6281 			srcu_read_unlock(&fs_info->subvol_srcu, index);
6282 			ret = PTR_ERR(sctx->parent_root);
6283 			goto out;
6284 		}
6285 
6286 		spin_lock(&sctx->parent_root->root_item_lock);
6287 		sctx->parent_root->send_in_progress++;
6288 		if (!btrfs_root_readonly(sctx->parent_root) ||
6289 				btrfs_root_dead(sctx->parent_root)) {
6290 			spin_unlock(&sctx->parent_root->root_item_lock);
6291 			srcu_read_unlock(&fs_info->subvol_srcu, index);
6292 			ret = -EPERM;
6293 			goto out;
6294 		}
6295 		spin_unlock(&sctx->parent_root->root_item_lock);
6296 
6297 		srcu_read_unlock(&fs_info->subvol_srcu, index);
6298 	}
6299 
6300 	/*
6301 	 * Clones from send_root are allowed, but only if the clone source
6302 	 * is behind the current send position. This is checked while searching
6303 	 * for possible clone sources.
6304 	 */
6305 	sctx->clone_roots[sctx->clone_roots_cnt++].root = sctx->send_root;
6306 
6307 	/* We do a bsearch later */
6308 	sort(sctx->clone_roots, sctx->clone_roots_cnt,
6309 			sizeof(*sctx->clone_roots), __clone_root_cmp_sort,
6310 			NULL);
6311 	sort_clone_roots = 1;
6312 
6313 	ret = ensure_commit_roots_uptodate(sctx);
6314 	if (ret)
6315 		goto out;
6316 
6317 	current->journal_info = BTRFS_SEND_TRANS_STUB;
6318 	ret = send_subvol(sctx);
6319 	current->journal_info = NULL;
6320 	if (ret < 0)
6321 		goto out;
6322 
6323 	if (!(sctx->flags & BTRFS_SEND_FLAG_OMIT_END_CMD)) {
6324 		ret = begin_cmd(sctx, BTRFS_SEND_C_END);
6325 		if (ret < 0)
6326 			goto out;
6327 		ret = send_cmd(sctx);
6328 		if (ret < 0)
6329 			goto out;
6330 	}
6331 
6332 out:
6333 	WARN_ON(sctx && !ret && !RB_EMPTY_ROOT(&sctx->pending_dir_moves));
6334 	while (sctx && !RB_EMPTY_ROOT(&sctx->pending_dir_moves)) {
6335 		struct rb_node *n;
6336 		struct pending_dir_move *pm;
6337 
6338 		n = rb_first(&sctx->pending_dir_moves);
6339 		pm = rb_entry(n, struct pending_dir_move, node);
6340 		while (!list_empty(&pm->list)) {
6341 			struct pending_dir_move *pm2;
6342 
6343 			pm2 = list_first_entry(&pm->list,
6344 					       struct pending_dir_move, list);
6345 			free_pending_move(sctx, pm2);
6346 		}
6347 		free_pending_move(sctx, pm);
6348 	}
6349 
6350 	WARN_ON(sctx && !ret && !RB_EMPTY_ROOT(&sctx->waiting_dir_moves));
6351 	while (sctx && !RB_EMPTY_ROOT(&sctx->waiting_dir_moves)) {
6352 		struct rb_node *n;
6353 		struct waiting_dir_move *dm;
6354 
6355 		n = rb_first(&sctx->waiting_dir_moves);
6356 		dm = rb_entry(n, struct waiting_dir_move, node);
6357 		rb_erase(&dm->node, &sctx->waiting_dir_moves);
6358 		kfree(dm);
6359 	}
6360 
6361 	WARN_ON(sctx && !ret && !RB_EMPTY_ROOT(&sctx->orphan_dirs));
6362 	while (sctx && !RB_EMPTY_ROOT(&sctx->orphan_dirs)) {
6363 		struct rb_node *n;
6364 		struct orphan_dir_info *odi;
6365 
6366 		n = rb_first(&sctx->orphan_dirs);
6367 		odi = rb_entry(n, struct orphan_dir_info, node);
6368 		free_orphan_dir_info(sctx, odi);
6369 	}
6370 
6371 	if (sort_clone_roots) {
6372 		for (i = 0; i < sctx->clone_roots_cnt; i++)
6373 			btrfs_root_dec_send_in_progress(
6374 					sctx->clone_roots[i].root);
6375 	} else {
6376 		for (i = 0; sctx && i < clone_sources_to_rollback; i++)
6377 			btrfs_root_dec_send_in_progress(
6378 					sctx->clone_roots[i].root);
6379 
6380 		btrfs_root_dec_send_in_progress(send_root);
6381 	}
6382 	if (sctx && !IS_ERR_OR_NULL(sctx->parent_root))
6383 		btrfs_root_dec_send_in_progress(sctx->parent_root);
6384 
6385 	kfree(arg);
6386 	kvfree(clone_sources_tmp);
6387 
6388 	if (sctx) {
6389 		if (sctx->send_filp)
6390 			fput(sctx->send_filp);
6391 
6392 		kvfree(sctx->clone_roots);
6393 		kvfree(sctx->send_buf);
6394 		kvfree(sctx->read_buf);
6395 
6396 		name_cache_free(sctx);
6397 
6398 		kfree(sctx);
6399 	}
6400 
6401 	return ret;
6402 }
6403