text: /*
   * Copyright (C) 2012 Alexander Block.  All rights reserved.
   *
   * This program is free software; you can redistribute it and/or
   * modify it under the terms of the GNU General Public
   * License v2 as published by the Free Software Foundation.
   *
   * This program is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   * General Public License for more details.
   *
   * You should have received a copy of the GNU General Public
   * License along with this program; if not, write to the
   * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
   * Boston, MA 021110-1307, USA.
   */
  
  #include <linux/bsearch.h>
  #include <linux/fs.h>
  #include <linux/file.h>
  #include <linux/sort.h>
  #include <linux/mount.h>
  #include <linux/xattr.h>
  #include <linux/posix_acl_xattr.h>
  #include <linux/radix-tree.h>
  #include <linux/vmalloc.h>
  #include <linux/string.h>
  
  #include "send.h"
  #include "backref.h"
  #include "hash.h"
  #include "locking.h"
  #include "disk-io.h"
  #include "btrfs_inode.h"
  #include "transaction.h"
  
  static int g_verbose = 0;
  
  #define verbose_printk(...) if (g_verbose) printk(__VA_ARGS__)
  
  /*
   * A fs_path is a helper to dynamically build path names with unknown size.
   * It reallocates the internal buffer on demand.
   * It allows fast adding of path elements on the right side (normal path) and
   * fast adding to the left side (reversed path). A reversed path can also be
   * unreversed if needed.
   */
  struct fs_path {
  	union {
  		struct {
  			char *start;
  			char *end;
  
  			char *buf;
  			unsigned short buf_len:15;
  			unsigned short reversed:1;
  			char inline_buf[];
  		};
  		/*
  		 * Average path length does not exceed 200 bytes, we'll have
  		 * better packing in the slab and higher chance to satisfy
  		 * a allocation later during send.
  		 */
  		char pad[256];
  	};
  };
  #define FS_PATH_INLINE_SIZE \
  	(sizeof(struct fs_path) - offsetof(struct fs_path, inline_buf))
  
  
  /* reused for each extent */
  struct clone_root {
  	struct btrfs_root *root;
  	u64 ino;
  	u64 offset;
  
  	u64 found_refs;
  };
  
  #define SEND_CTX_MAX_NAME_CACHE_SIZE 128
  #define SEND_CTX_NAME_CACHE_CLEAN_SIZE (SEND_CTX_MAX_NAME_CACHE_SIZE * 2)
  
  struct send_ctx {
  	struct file *send_filp;
  	loff_t send_off;
  	char *send_buf;
  	u32 send_size;
  	u32 send_max_size;
  	u64 total_send_size;
  	u64 cmd_send_size[BTRFS_SEND_C_MAX + 1];
  	u64 flags;	/* 'flags' member of btrfs_ioctl_send_args is u64 */
  
  	struct btrfs_root *send_root;
  	struct btrfs_root *parent_root;
  	struct clone_root *clone_roots;
  	int clone_roots_cnt;
  
  	/* current state of the compare_tree call */
  	struct btrfs_path *left_path;
  	struct btrfs_path *right_path;
  	struct btrfs_key *cmp_key;
  
  	/*
  	 * infos of the currently processed inode. In case of deleted inodes,
  	 * these are the values from the deleted inode.
  	 */
  	u64 cur_ino;
  	u64 cur_inode_gen;
  	int cur_inode_new;
  	int cur_inode_new_gen;
  	int cur_inode_deleted;
  	u64 cur_inode_size;
  	u64 cur_inode_mode;
  	u64 cur_inode_rdev;
  	u64 cur_inode_last_extent;
  
  	u64 send_progress;
  
  	struct list_head new_refs;
  	struct list_head deleted_refs;
  
  	struct radix_tree_root name_cache;
  	struct list_head name_cache_list;
  	int name_cache_size;
  
  	struct file_ra_state ra;
  
  	char *read_buf;
  
  	/*
  	 * We process inodes by their increasing order, so if before an
  	 * incremental send we reverse the parent/child relationship of
  	 * directories such that a directory with a lower inode number was
  	 * the parent of a directory with a higher inode number, and the one
  	 * becoming the new parent got renamed too, we can't rename/move the
  	 * directory with lower inode number when we finish processing it - we
  	 * must process the directory with higher inode number first, then
  	 * rename/move it and then rename/move the directory with lower inode
  	 * number. Example follows.
  	 *
  	 * Tree state when the first send was performed:
  	 *
  	 * .
  	 * |-- a                   (ino 257)
  	 *     |-- b               (ino 258)
  	 *         |
  	 *         |
  	 *         |-- c           (ino 259)
  	 *         |   |-- d       (ino 260)
  	 *         |
  	 *         |-- c2          (ino 261)
  	 *
  	 * Tree state when the second (incremental) send is performed:
  	 *
  	 * .
  	 * |-- a                   (ino 257)
  	 *     |-- b               (ino 258)
  	 *         |-- c2          (ino 261)
  	 *             |-- d2      (ino 260)
  	 *                 |-- cc  (ino 259)
  	 *
  	 * The sequence of steps that lead to the second state was:
  	 *
  	 * mv /a/b/c/d /a/b/c2/d2
  	 * mv /a/b/c /a/b/c2/d2/cc
  	 *
  	 * "c" has lower inode number, but we can't move it (2nd mv operation)
  	 * before we move "d", which has higher inode number.
  	 *
  	 * So we just memorize which move/rename operations must be performed
  	 * later when their respective parent is processed and moved/renamed.
  	 */
  
  	/* Indexed by parent directory inode number. */
  	struct rb_root pending_dir_moves;
  
  	/*
  	 * Reverse index, indexed by the inode number of a directory that
  	 * is waiting for the move/rename of its immediate parent before its
  	 * own move/rename can be performed.
  	 */
  	struct rb_root waiting_dir_moves;
  
  	/*
  	 * A directory that is going to be rm'ed might have a child directory
  	 * which is in the pending directory moves index above. In this case,
  	 * the directory can only be removed after the move/rename of its child
  	 * is performed. Example:
  	 *
  	 * Parent snapshot:
  	 *
  	 * .                        (ino 256)
  	 * |-- a/                   (ino 257)
  	 *     |-- b/               (ino 258)
  	 *         |-- c/           (ino 259)
  	 *         |   |-- x/       (ino 260)
  	 *         |
  	 *         |-- y/           (ino 261)
  	 *
  	 * Send snapshot:
  	 *
  	 * .                        (ino 256)
  	 * |-- a/                   (ino 257)
  	 *     |-- b/               (ino 258)
  	 *         |-- YY/          (ino 261)
  	 *              |-- x/      (ino 260)
  	 *
  	 * Sequence of steps that lead to the send snapshot:
  	 * rm -f /a/b/c/foo.txt
  	 * mv /a/b/y /a/b/YY
  	 * mv /a/b/c/x /a/b/YY
  	 * rmdir /a/b/c
  	 *
  	 * When the child is processed, its move/rename is delayed until its
  	 * parent is processed (as explained above), but all other operations
  	 * like update utimes, chown, chgrp, etc, are performed and the paths
  	 * that it uses for those operations must use the orphanized name of
  	 * its parent (the directory we're going to rm later), so we need to
  	 * memorize that name.
  	 *
  	 * Indexed by the inode number of the directory to be deleted.
  	 */
  	struct rb_root orphan_dirs;
  };
  
  struct pending_dir_move {
  	struct rb_node node;
  	struct list_head list;
  	u64 parent_ino;
  	u64 ino;
  	u64 gen;
  	bool is_orphan;
  	struct list_head update_refs;
  };
  
  struct waiting_dir_move {
  	struct rb_node node;
  	u64 ino;
  	/*
  	 * There might be some directory that could not be removed because it
  	 * was waiting for this directory inode to be moved first. Therefore
  	 * after this directory is moved, we can try to rmdir the ino rmdir_ino.
  	 */
  	u64 rmdir_ino;
  	bool orphanized;
  };
  
  struct orphan_dir_info {
  	struct rb_node node;
  	u64 ino;
  	u64 gen;
  };
  
  struct name_cache_entry {
  	struct list_head list;
  	/*
  	 * radix_tree has only 32bit entries but we need to handle 64bit inums.
  	 * We use the lower 32bit of the 64bit inum to store it in the tree. If
  	 * more then one inum would fall into the same entry, we use radix_list
  	 * to store the additional entries. radix_list is also used to store
  	 * entries where two entries have the same inum but different
  	 * generations.
  	 */
  	struct list_head radix_list;
  	u64 ino;
  	u64 gen;
  	u64 parent_ino;
  	u64 parent_gen;
  	int ret;
  	int need_later_update;
  	int name_len;
  	char name[];
  };
  
  static int is_waiting_for_move(struct send_ctx *sctx, u64 ino);
  
  static struct waiting_dir_move *
  get_waiting_dir_move(struct send_ctx *sctx, u64 ino);
  
  static int is_waiting_for_rm(struct send_ctx *sctx, u64 dir_ino);
  
  static int need_send_hole(struct send_ctx *sctx)
  {
  	return (sctx->parent_root && !sctx->cur_inode_new &&
  		!sctx->cur_inode_new_gen && !sctx->cur_inode_deleted &&
  		S_ISREG(sctx->cur_inode_mode));
  }
  
  static void fs_path_reset(struct fs_path *p)
  {
  	if (p->reversed) {
  		p->start = p->buf + p->buf_len - 1;
  		p->end = p->start;
  		*p->start = 0;
  	} else {
  		p->start = p->buf;
  		p->end = p->start;
  		*p->start = 0;
  	}
  }
  
  static struct fs_path *fs_path_alloc(void)
  {
  	struct fs_path *p;
  
  	p = kmalloc(sizeof(*p), GFP_NOFS);
  	if (!p)
  		return NULL;
  	p->reversed = 0;
  	p->buf = p->inline_buf;
  	p->buf_len = FS_PATH_INLINE_SIZE;
  	fs_path_reset(p);
  	return p;
  }
  
  static struct fs_path *fs_path_alloc_reversed(void)
  {
  	struct fs_path *p;
  
  	p = fs_path_alloc();
  	if (!p)
  		return NULL;
  	p->reversed = 1;
  	fs_path_reset(p);
  	return p;
  }
  
  static void fs_path_free(struct fs_path *p)
  {
  	if (!p)
  		return;
  	if (p->buf != p->inline_buf)
  		kfree(p->buf);
  	kfree(p);
  }
  
  static int fs_path_len(struct fs_path *p)
  {
  	return p->end - p->start;
  }
  
  static int fs_path_ensure_buf(struct fs_path *p, int len)
  {
  	char *tmp_buf;
  	int path_len;
  	int old_buf_len;
  
  	len++;
  
  	if (p->buf_len >= len)
  		return 0;
  
  	if (len > PATH_MAX) {
  		WARN_ON(1);
  		return -ENOMEM;
  	}
  
  	path_len = p->end - p->start;
  	old_buf_len = p->buf_len;
  
  	/*
  	 * First time the inline_buf does not suffice
  	 */
  	if (p->buf == p->inline_buf) {
  		tmp_buf = kmalloc(len, GFP_NOFS);
  		if (tmp_buf)
  			memcpy(tmp_buf, p->buf, old_buf_len);
  	} else {
  		tmp_buf = krealloc(p->buf, len, GFP_NOFS);
  	}
  	if (!tmp_buf)
  		return -ENOMEM;
  	p->buf = tmp_buf;
  	/*
  	 * The real size of the buffer is bigger, this will let the fast path
  	 * happen most of the time
  	 */
  	p->buf_len = ksize(p->buf);
  
  	if (p->reversed) {
  		tmp_buf = p->buf + old_buf_len - path_len - 1;
  		p->end = p->buf + p->buf_len - 1;
  		p->start = p->end - path_len;
  		memmove(p->start, tmp_buf, path_len + 1);
  	} else {
  		p->start = p->buf;
  		p->end = p->start + path_len;
  	}
  	return 0;
  }
  
  static int fs_path_prepare_for_add(struct fs_path *p, int name_len,
  				   char **prepared)
  {
  	int ret;
  	int new_len;
  
  	new_len = p->end - p->start + name_len;
  	if (p->start != p->end)
  		new_len++;
  	ret = fs_path_ensure_buf(p, new_len);
  	if (ret < 0)
  		goto out;
  
  	if (p->reversed) {
  		if (p->start != p->end)
  			*--p->start = '/';
  		p->start -= name_len;
  		*prepared = p->start;
  	} else {
  		if (p->start != p->end)
  			*p->end++ = '/';
  		*prepared = p->end;
  		p->end += name_len;
  		*p->end = 0;
  	}
  
  out:
  	return ret;
  }
  
  static int fs_path_add(struct fs_path *p, const char *name, int name_len)
  {
  	int ret;
  	char *prepared;
  
  	ret = fs_path_prepare_for_add(p, name_len, &prepared);
  	if (ret < 0)
  		goto out;
  	memcpy(prepared, name, name_len);
  
  out:
  	return ret;
  }
  
  static int fs_path_add_path(struct fs_path *p, struct fs_path *p2)
  {
  	int ret;
  	char *prepared;
  
  	ret = fs_path_prepare_for_add(p, p2->end - p2->start, &prepared);
  	if (ret < 0)
  		goto out;
  	memcpy(prepared, p2->start, p2->end - p2->start);
  
  out:
  	return ret;
  }
  
  static int fs_path_add_from_extent_buffer(struct fs_path *p,
  					  struct extent_buffer *eb,
  					  unsigned long off, int len)
  {
  	int ret;
  	char *prepared;
  
  	ret = fs_path_prepare_for_add(p, len, &prepared);
  	if (ret < 0)
  		goto out;
  
  	read_extent_buffer(eb, prepared, off, len);
  
  out:
  	return ret;
  }
  
  static int fs_path_copy(struct fs_path *p, struct fs_path *from)
  {
  	int ret;
  
  	p->reversed = from->reversed;
  	fs_path_reset(p);
  
  	ret = fs_path_add_path(p, from);
  
  	return ret;
  }
  
  
  static void fs_path_unreverse(struct fs_path *p)
  {
  	char *tmp;
  	int len;
  
  	if (!p->reversed)
  		return;
  
  	tmp = p->start;
  	len = p->end - p->start;
  	p->start = p->buf;
  	p->end = p->start + len;
  	memmove(p->start, tmp, len + 1);
  	p->reversed = 0;
  }
  
  static struct btrfs_path *alloc_path_for_send(void)
  {
  	struct btrfs_path *path;
  
  	path = btrfs_alloc_path();
  	if (!path)
  		return NULL;
  	path->search_commit_root = 1;
  	path->skip_locking = 1;
  	path->need_commit_sem = 1;
  	return path;
  }
  
  static int write_buf(struct file *filp, const void *buf, u32 len, loff_t *off)
  {
  	int ret;
  	mm_segment_t old_fs;
  	u32 pos = 0;
  
  	old_fs = get_fs();
  	set_fs(KERNEL_DS);
  
  	while (pos < len) {
  		ret = vfs_write(filp, (__force const char __user *)buf + pos,
  				len - pos, off);
  		/* TODO handle that correctly */
  		/*if (ret == -ERESTARTSYS) {
  			continue;
  		}*/
  		if (ret < 0)
  			goto out;
  		if (ret == 0) {
  			ret = -EIO;
  			goto out;
  		}
  		pos += ret;
  	}
  
  	ret = 0;
  
  out:
  	set_fs(old_fs);
  	return ret;
  }
  
  static int tlv_put(struct send_ctx *sctx, u16 attr, const void *data, int len)
  {
  	struct btrfs_tlv_header *hdr;
  	int total_len = sizeof(*hdr) + len;
  	int left = sctx->send_max_size - sctx->send_size;
  
  	if (unlikely(left < total_len))
  		return -EOVERFLOW;
  
  	hdr = (struct btrfs_tlv_header *) (sctx->send_buf + sctx->send_size);
  	hdr->tlv_type = cpu_to_le16(attr);
  	hdr->tlv_len = cpu_to_le16(len);
  	memcpy(hdr + 1, data, len);
  	sctx->send_size += total_len;
  
  	return 0;
  }
  
  #define TLV_PUT_DEFINE_INT(bits) \
  	static int tlv_put_u##bits(struct send_ctx *sctx,	 	\
  			u##bits attr, u##bits value)			\
  	{								\
  		__le##bits __tmp = cpu_to_le##bits(value);		\
  		return tlv_put(sctx, attr, &__tmp, sizeof(__tmp));	\
  	}
  
  TLV_PUT_DEFINE_INT(64)
  
  static int tlv_put_string(struct send_ctx *sctx, u16 attr,
  			  const char *str, int len)
  {
  	if (len == -1)
  		len = strlen(str);
  	return tlv_put(sctx, attr, str, len);
  }
  
  static int tlv_put_uuid(struct send_ctx *sctx, u16 attr,
  			const u8 *uuid)
  {
  	return tlv_put(sctx, attr, uuid, BTRFS_UUID_SIZE);
  }
  
  static int tlv_put_btrfs_timespec(struct send_ctx *sctx, u16 attr,
  				  struct extent_buffer *eb,
  				  struct btrfs_timespec *ts)
  {
  	struct btrfs_timespec bts;
  	read_extent_buffer(eb, &bts, (unsigned long)ts, sizeof(bts));
  	return tlv_put(sctx, attr, &bts, sizeof(bts));
  }
  
  
  #define TLV_PUT(sctx, attrtype, attrlen, data) \
  	do { \
  		ret = tlv_put(sctx, attrtype, attrlen, data); \
  		if (ret < 0) \
  			goto tlv_put_failure; \
  	} while (0)
  
  #define TLV_PUT_INT(sctx, attrtype, bits, value) \
  	do { \
  		ret = tlv_put_u##bits(sctx, attrtype, value); \
  		if (ret < 0) \
  			goto tlv_put_failure; \
  	} while (0)
  
  #define TLV_PUT_U8(sctx, attrtype, data) TLV_PUT_INT(sctx, attrtype, 8, data)
  #define TLV_PUT_U16(sctx, attrtype, data) TLV_PUT_INT(sctx, attrtype, 16, data)
  #define TLV_PUT_U32(sctx, attrtype, data) TLV_PUT_INT(sctx, attrtype, 32, data)
  #define TLV_PUT_U64(sctx, attrtype, data) TLV_PUT_INT(sctx, attrtype, 64, data)
  #define TLV_PUT_STRING(sctx, attrtype, str, len) \
  	do { \
  		ret = tlv_put_string(sctx, attrtype, str, len); \
  		if (ret < 0) \
  			goto tlv_put_failure; \
  	} while (0)
  #define TLV_PUT_PATH(sctx, attrtype, p) \
  	do { \
  		ret = tlv_put_string(sctx, attrtype, p->start, \
  			p->end - p->start); \
  		if (ret < 0) \
  			goto tlv_put_failure; \
  	} while(0)
  #define TLV_PUT_UUID(sctx, attrtype, uuid) \
  	do { \
  		ret = tlv_put_uuid(sctx, attrtype, uuid); \
  		if (ret < 0) \
  			goto tlv_put_failure; \
  	} while (0)
  #define TLV_PUT_BTRFS_TIMESPEC(sctx, attrtype, eb, ts) \
  	do { \
  		ret = tlv_put_btrfs_timespec(sctx, attrtype, eb, ts); \
  		if (ret < 0) \
  			goto tlv_put_failure; \
  	} while (0)
  
  static int send_header(struct send_ctx *sctx)
  {
  	struct btrfs_stream_header hdr;
  
  	strcpy(hdr.magic, BTRFS_SEND_STREAM_MAGIC);
  	hdr.version = cpu_to_le32(BTRFS_SEND_STREAM_VERSION);
  
  	return write_buf(sctx->send_filp, &hdr, sizeof(hdr),
  					&sctx->send_off);
  }
  
  /*
   * For each command/item we want to send to userspace, we call this function.
   */
  static int begin_cmd(struct send_ctx *sctx, int cmd)
  {
  	struct btrfs_cmd_header *hdr;
  
  	if (WARN_ON(!sctx->send_buf))
  		return -EINVAL;
  
  	BUG_ON(sctx->send_size);
  
  	sctx->send_size += sizeof(*hdr);
  	hdr = (struct btrfs_cmd_header *)sctx->send_buf;
  	hdr->cmd = cpu_to_le16(cmd);
  
  	return 0;
  }
  
  static int send_cmd(struct send_ctx *sctx)
  {
  	int ret;
  	struct btrfs_cmd_header *hdr;
  	u32 crc;
  
  	hdr = (struct btrfs_cmd_header *)sctx->send_buf;
  	hdr->len = cpu_to_le32(sctx->send_size - sizeof(*hdr));
  	hdr->crc = 0;
  
  	crc = btrfs_crc32c(0, (unsigned char *)sctx->send_buf, sctx->send_size);
  	hdr->crc = cpu_to_le32(crc);
  
  	ret = write_buf(sctx->send_filp, sctx->send_buf, sctx->send_size,
  					&sctx->send_off);
  
  	sctx->total_send_size += sctx->send_size;
  	sctx->cmd_send_size[le16_to_cpu(hdr->cmd)] += sctx->send_size;
  	sctx->send_size = 0;
  
  	return ret;
  }
  
  /*
   * Sends a move instruction to user space
   */
  static int send_rename(struct send_ctx *sctx,
  		     struct fs_path *from, struct fs_path *to)
  {
  	int ret;
  
  verbose_printk("btrfs: send_rename %s -> %s\n", from->start, to->start);
  
  	ret = begin_cmd(sctx, BTRFS_SEND_C_RENAME);
  	if (ret < 0)
  		goto out;
  
  	TLV_PUT_PATH(sctx, BTRFS_SEND_A_PATH, from);
  	TLV_PUT_PATH(sctx, BTRFS_SEND_A_PATH_TO, to);
  
  	ret = send_cmd(sctx);
  
  tlv_put_failure:
  out:
  	return ret;
  }
  
  /*
   * Sends a link instruction to user space
   */
  static int send_link(struct send_ctx *sctx,
  		     struct fs_path *path, struct fs_path *lnk)
  {
  	int ret;
  
  verbose_printk("btrfs: send_link %s -> %s\n", path->start, lnk->start);
  
  	ret = begin_cmd(sctx, BTRFS_SEND_C_LINK);
  	if (ret < 0)
  		goto out;
  
  	TLV_PUT_PATH(sctx, BTRFS_SEND_A_PATH, path);
  	TLV_PUT_PATH(sctx, BTRFS_SEND_A_PATH_LINK, lnk);
  
  	ret = send_cmd(sctx);
  
  tlv_put_failure:
  out:
  	return ret;
  }
  
  /*
   * Sends an unlink instruction to user space
   */
  static int send_unlink(struct send_ctx *sctx, struct fs_path *path)
  {
  	int ret;
  
  verbose_printk("btrfs: send_unlink %s\n", path->start);
  
  	ret = begin_cmd(sctx, BTRFS_SEND_C_UNLINK);
  	if (ret < 0)
  		goto out;
  
  	TLV_PUT_PATH(sctx, BTRFS_SEND_A_PATH, path);
  
  	ret = send_cmd(sctx);
  
  tlv_put_failure:
  out:
  	return ret;
  }
  
  /*
   * Sends a rmdir instruction to user space
   */
  static int send_rmdir(struct send_ctx *sctx, struct fs_path *path)
  {
  	int ret;
  
  verbose_printk("btrfs: send_rmdir %s\n", path->start);
  
  	ret = begin_cmd(sctx, BTRFS_SEND_C_RMDIR);
  	if (ret < 0)
  		goto out;
  
  	TLV_PUT_PATH(sctx, BTRFS_SEND_A_PATH, path);
  
  	ret = send_cmd(sctx);
  
  tlv_put_failure:
  out:
  	return ret;
  }
  
  /*
   * Helper function to retrieve some fields from an inode item.
   */
  static int __get_inode_info(struct btrfs_root *root, struct btrfs_path *path,
  			  u64 ino, u64 *size, u64 *gen, u64 *mode, u64 *uid,
  			  u64 *gid, u64 *rdev)
  {
  	int ret;
  	struct btrfs_inode_item *ii;
  	struct btrfs_key key;
  
  	key.objectid = ino;
  	key.type = BTRFS_INODE_ITEM_KEY;
  	key.offset = 0;
  	ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
  	if (ret) {
  		if (ret > 0)
  			ret = -ENOENT;
  		return ret;
  	}
  
  	ii = btrfs_item_ptr(path->nodes[0], path->slots[0],
  			struct btrfs_inode_item);
  	if (size)
  		*size = btrfs_inode_size(path->nodes[0], ii);
  	if (gen)
  		*gen = btrfs_inode_generation(path->nodes[0], ii);
  	if (mode)
  		*mode = btrfs_inode_mode(path->nodes[0], ii);
  	if (uid)
  		*uid = btrfs_inode_uid(path->nodes[0], ii);
  	if (gid)
  		*gid = btrfs_inode_gid(path->nodes[0], ii);
  	if (rdev)
  		*rdev = btrfs_inode_rdev(path->nodes[0], ii);
  
  	return ret;
  }
  
  static int get_inode_info(struct btrfs_root *root,
  			  u64 ino, u64 *size, u64 *gen,
  			  u64 *mode, u64 *uid, u64 *gid,
  			  u64 *rdev)
  {
  	struct btrfs_path *path;
  	int ret;
  
  	path = alloc_path_for_send();
  	if (!path)
  		return -ENOMEM;
  	ret = __get_inode_info(root, path, ino, size, gen, mode, uid, gid,
  			       rdev);
  	btrfs_free_path(path);
  	return ret;
  }
  
  typedef int (*iterate_inode_ref_t)(int num, u64 dir, int index,
  				   struct fs_path *p,
  				   void *ctx);
  
  /*
   * Helper function to iterate the entries in ONE btrfs_inode_ref or
   * btrfs_inode_extref.
   * The iterate callback may return a non zero value to stop iteration. This can
   * be a negative value for error codes or 1 to simply stop it.
   *
   * path must point to the INODE_REF or INODE_EXTREF when called.
   */
  static int iterate_inode_ref(struct btrfs_root *root, struct btrfs_path *path,
  			     struct btrfs_key *found_key, int resolve,
  			     iterate_inode_ref_t iterate, void *ctx)
  {
  	struct extent_buffer *eb = path->nodes[0];
  	struct btrfs_item *item;
  	struct btrfs_inode_ref *iref;
  	struct btrfs_inode_extref *extref;
  	struct btrfs_path *tmp_path;
  	struct fs_path *p;
  	u32 cur = 0;
  	u32 total;
  	int slot = path->slots[0];
  	u32 name_len;
  	char *start;
  	int ret = 0;
  	int num = 0;
  	int index;
  	u64 dir;
  	unsigned long name_off;
  	unsigned long elem_size;
  	unsigned long ptr;
  
  	p = fs_path_alloc_reversed();
  	if (!p)
  		return -ENOMEM;
  
  	tmp_path = alloc_path_for_send();
  	if (!tmp_path) {
  		fs_path_free(p);
  		return -ENOMEM;
  	}
  
  
  	if (found_key->type == BTRFS_INODE_REF_KEY) {
  		ptr = (unsigned long)btrfs_item_ptr(eb, slot,
  						    struct btrfs_inode_ref);
  		item = btrfs_item_nr(slot);
  		total = btrfs_item_size(eb, item);
  		elem_size = sizeof(*iref);
  	} else {
  		ptr = btrfs_item_ptr_offset(eb, slot);
  		total = btrfs_item_size_nr(eb, slot);
  		elem_size = sizeof(*extref);
  	}
  
  	while (cur < total) {
  		fs_path_reset(p);
  
  		if (found_key->type == BTRFS_INODE_REF_KEY) {
  			iref = (struct btrfs_inode_ref *)(ptr + cur);
  			name_len = btrfs_inode_ref_name_len(eb, iref);
  			name_off = (unsigned long)(iref + 1);
  			index = btrfs_inode_ref_index(eb, iref);
  			dir = found_key->offset;
  		} else {
  			extref = (struct btrfs_inode_extref *)(ptr + cur);
  			name_len = btrfs_inode_extref_name_len(eb, extref);
  			name_off = (unsigned long)&extref->name;
  			index = btrfs_inode_extref_index(eb, extref);
  			dir = btrfs_inode_extref_parent(eb, extref);
  		}
  
  		if (resolve) {
  			start = btrfs_ref_to_path(root, tmp_path, name_len,
  						  name_off, eb, dir,
  						  p->buf, p->buf_len);
  			if (IS_ERR(start)) {
  				ret = PTR_ERR(start);
  				goto out;
  			}
  			if (start < p->buf) {
  				/* overflow , try again with larger buffer */
  				ret = fs_path_ensure_buf(p,
  						p->buf_len + p->buf - start);
  				if (ret < 0)
  					goto out;
  				start = btrfs_ref_to_path(root, tmp_path,
  							  name_len, name_off,
  							  eb, dir,
  							  p->buf, p->buf_len);
  				if (IS_ERR(start)) {
  					ret = PTR_ERR(start);
  					goto out;
  				}
  				BUG_ON(start < p->buf);
  			}
  			p->start = start;
  		} else {
  			ret = fs_path_add_from_extent_buffer(p, eb, name_off,
  							     name_len);
  			if (ret < 0)
  				goto out;
  		}
  
  		cur += elem_size + name_len;
  		ret = iterate(num, dir, index, p, ctx);
  		if (ret)
  			goto out;
  		num++;
  	}
  
  out:
  	btrfs_free_path(tmp_path);
  	fs_path_free(p);
  	return ret;
  }
  
  typedef int (*iterate_dir_item_t)(int num, struct btrfs_key *di_key,
  				  const char *name, int name_len,
  				  const char *data, int data_len,
  				  u8 type, void *ctx);
  
  /*
   * Helper function to iterate the entries in ONE btrfs_dir_item.
   * The iterate callback may return a non zero value to stop iteration. This can
   * be a negative value for error codes or 1 to simply stop it.
   *
   * path must point to the dir item when called.
   */
  static int iterate_dir_item(struct btrfs_root *root, struct btrfs_path *path,
  			    struct btrfs_key *found_key,
  			    iterate_dir_item_t iterate, void *ctx)
  {
  	int ret = 0;
  	struct extent_buffer *eb;
  	struct btrfs_item *item;
  	struct btrfs_dir_item *di;
  	struct btrfs_key di_key;
  	char *buf = NULL;
  	int buf_len;
  	u32 name_len;
  	u32 data_len;
  	u32 cur;
  	u32 len;
  	u32 total;
  	int slot;
  	int num;
  	u8 type;
  
  	/*
  	 * Start with a small buffer (1 page). If later we end up needing more
  	 * space, which can happen for xattrs on a fs with a leaf size greater
  	 * then the page size, attempt to increase the buffer. Typically xattr
  	 * values are small.
  	 */
  	buf_len = PATH_MAX;
  	buf = kmalloc(buf_len, GFP_NOFS);
  	if (!buf) {
  		ret = -ENOMEM;
  		goto out;
  	}
  
  	eb = path->nodes[0];
  	slot = path->slots[0];
  	item = btrfs_item_nr(slot);
  	di = btrfs_item_ptr(eb, slot, struct btrfs_dir_item);
  	cur = 0;
  	len = 0;
  	total = btrfs_item_size(eb, item);
  
  	num = 0;
  	while (cur < total) {
  		name_len = btrfs_dir_name_len(eb, di);
  		data_len = btrfs_dir_data_len(eb, di);
  		type = btrfs_dir_type(eb, di);
  		btrfs_dir_item_key_to_cpu(eb, di, &di_key);
  
  		if (type == BTRFS_FT_XATTR) {
  			if (name_len > XATTR_NAME_MAX) {
  				ret = -ENAMETOOLONG;
  				goto out;
  			}
  			if (name_len + data_len > BTRFS_MAX_XATTR_SIZE(root)) {
  				ret = -E2BIG;
  				goto out;
  			}
  		} else {
  			/*
  			 * Path too long
  			 */
  			if (name_len + data_len > PATH_MAX) {
  				ret = -ENAMETOOLONG;
  				goto out;
  			}
  		}
  
  		if (name_len + data_len > buf_len) {
  			buf_len = name_len + data_len;
  			if (is_vmalloc_addr(buf)) {
  				vfree(buf);
  				buf = NULL;
  			} else {
  				char *tmp = krealloc(buf, buf_len,
  						     GFP_NOFS | __GFP_NOWARN);
  
  				if (!tmp)
  					kfree(buf);
  				buf = tmp;
  			}
  			if (!buf) {
  				buf = vmalloc(buf_len);
  				if (!buf) {
  					ret = -ENOMEM;
  					goto out;
  				}
  			}
  		}
  
  		read_extent_buffer(eb, buf, (unsigned long)(di + 1),
  				name_len + data_len);
  
  		len = sizeof(*di) + name_len + data_len;
  		di = (struct btrfs_dir_item *)((char *)di + len);
  		cur += len;
  
  		ret = iterate(num, &di_key, buf, name_len, buf + name_len,
  				data_len, type, ctx);
  		if (ret < 0)
  			goto out;
  		if (ret) {
  			ret = 0;
  			goto out;
  		}
  
  		num++;
  	}
  
  out:
  	kvfree(buf);
  	return ret;
  }
  
  static int __copy_first_ref(int num, u64 dir, int index,
  			    struct fs_path *p, void *ctx)
  {
  	int ret;
  	struct fs_path *pt = ctx;
  
  	ret = fs_path_copy(pt, p);
  	if (ret < 0)
  		return ret;
  
  	/* we want the first only */
  	return 1;
  }
  
  /*
   * Retrieve the first path of an inode. If an inode has more then one
   * ref/hardlink, this is ignored.
   */
  static int get_inode_path(struct btrfs_root *root,
  			  u64 ino, struct fs_path *path)
  {
  	int ret;
  	struct btrfs_key key, found_key;
  	struct btrfs_path *p;
  
  	p = alloc_path_for_send();
  	if (!p)
  		return -ENOMEM;
  
  	fs_path_reset(path);
  
  	key.objectid = ino;
  	key.type = BTRFS_INODE_REF_KEY;
  	key.offset = 0;
  
  	ret = btrfs_search_slot_for_read(root, &key, p, 1, 0);
  	if (ret < 0)
  		goto out;
  	if (ret) {
  		ret = 1;
  		goto out;
  	}
  	btrfs_item_key_to_cpu(p->nodes[0], &found_key, p->slots[0]);
  	if (found_key.objectid != ino ||
  	    (found_key.type != BTRFS_INODE_REF_KEY &&
  	     found_key.type != BTRFS_INODE_EXTREF_KEY)) {
  		ret = -ENOENT;
  		goto out;
  	}
  
  	ret = iterate_inode_ref(root, p, &found_key, 1,
  				__copy_first_ref, path);
  	if (ret < 0)
  		goto out;
  	ret = 0;
  
  out:
  	btrfs_free_path(p);
  	return ret;
  }
  
  struct backref_ctx {
  	struct send_ctx *sctx;
  
  	struct btrfs_path *path;
  	/* number of total found references */
  	u64 found;
  
  	/*
  	 * used for clones found in send_root. clones found behind cur_objectid
  	 * and cur_offset are not considered as allowed clones.
  	 */
  	u64 cur_objectid;
  	u64 cur_offset;
  
  	/* may be truncated in case it's the last extent in a file */
  	u64 extent_len;
  
  	/* data offset in the file extent item */
  	u64 data_offset;
  
  	/* Just to check for bugs in backref resolving */
  	int found_itself;
  };
  
  static int __clone_root_cmp_bsearch(const void *key, const void *elt)
  {
  	u64 root = (u64)(uintptr_t)key;
  	struct clone_root *cr = (struct clone_root *)elt;
  
  	if (root < cr->root->objectid)
  		return -1;
  	if (root > cr->root->objectid)
  		return 1;
  	return 0;
  }
  
  static int __clone_root_cmp_sort(const void *e1, const void *e2)
  {
  	struct clone_root *cr1 = (struct clone_root *)e1;
  	struct clone_root *cr2 = (struct clone_root *)e2;
  
  	if (cr1->root->objectid < cr2->root->objectid)
  		return -1;
  	if (cr1->root->objectid > cr2->root->objectid)
  		return 1;
  	return 0;
  }
  
  /*
   * Called for every backref that is found for the current extent.
   * Results are collected in sctx->clone_roots->ino/offset/found_refs
   */
  static int __iterate_backrefs(u64 ino, u64 offset, u64 root, void *ctx_)
  {
  	struct backref_ctx *bctx = ctx_;
  	struct clone_root *found;
  	int ret;
  	u64 i_size;
  
  	/* First check if the root is in the list of accepted clone sources */
  	found = bsearch((void *)(uintptr_t)root, bctx->sctx->clone_roots,
  			bctx->sctx->clone_roots_cnt,
  			sizeof(struct clone_root),
  			__clone_root_cmp_bsearch);
  	if (!found)
  		return 0;
  
  	if (found->root == bctx->sctx->send_root &&
  	    ino == bctx->cur_objectid &&
  	    offset == bctx->cur_offset) {
  		bctx->found_itself = 1;
  	}
  
  	/*
  	 * There are inodes that have extents that lie behind its i_size. Don't
  	 * accept clones from these extents.
  	 */
  	ret = __get_inode_info(found->root, bctx->path, ino, &i_size, NULL, NULL,
  			       NULL, NULL, NULL);
  	btrfs_release_path(bctx->path);
  	if (ret < 0)
  		return ret;
  
  	if (offset + bctx->data_offset + bctx->extent_len > i_size)
  		return 0;
  
  	/*
  	 * Make sure we don't consider clones from send_root that are
  	 * behind the current inode/offset.
  	 */
  	if (found->root == bctx->sctx->send_root) {
  		/*
  		 * TODO for the moment we don't accept clones from the inode
  		 * that is currently send. We may change this when
  		 * BTRFS_IOC_CLONE_RANGE supports cloning from and to the same
  		 * file.
  		 */
  		if (ino >= bctx->cur_objectid)
  			return 0;
  #if 0
  		if (ino > bctx->cur_objectid)
  			return 0;
  		if (offset + bctx->extent_len > bctx->cur_offset)
  			return 0;
  #endif
  	}
  
  	bctx->found++;
  	found->found_refs++;
  	if (ino < found->ino) {
  		found->ino = ino;
  		found->offset = offset;
  	} else if (found->ino == ino) {
  		/*
  		 * same extent found more then once in the same file.
  		 */
  		if (found->offset > offset + bctx->extent_len)
  			found->offset = offset;
  	}
  
  	return 0;
  }
  
  /*
   * Given an inode, offset and extent item, it finds a good clone for a clone
   * instruction. Returns -ENOENT when none could be found. The function makes
   * sure that the returned clone is usable at the point where sending is at the
   * moment. This means, that no clones are accepted which lie behind the current
   * inode+offset.
   *
   * path must point to the extent item when called.
   */
  static int find_extent_clone(struct send_ctx *sctx,
  			     struct btrfs_path *path,
  			     u64 ino, u64 data_offset,
  			     u64 ino_size,
  			     struct clone_root **found)
  {
  	int ret;
  	int extent_type;
  	u64 logical;
  	u64 disk_byte;
  	u64 num_bytes;
  	u64 extent_item_pos;
  	u64 flags = 0;
  	struct btrfs_file_extent_item *fi;
  	struct extent_buffer *eb = path->nodes[0];
  	struct backref_ctx *backref_ctx = NULL;
  	struct clone_root *cur_clone_root;
  	struct btrfs_key found_key;
  	struct btrfs_path *tmp_path;
  	int compressed;
  	u32 i;
  
  	tmp_path = alloc_path_for_send();
  	if (!tmp_path)
  		return -ENOMEM;
  
  	/* We only use this path under the commit sem */
  	tmp_path->need_commit_sem = 0;
  
  	backref_ctx = kmalloc(sizeof(*backref_ctx), GFP_NOFS);
  	if (!backref_ctx) {
  		ret = -ENOMEM;
  		goto out;
  	}
  
  	backref_ctx->path = tmp_path;
  
  	if (data_offset >= ino_size) {
  		/*
  		 * There may be extents that lie behind the file's size.
  		 * I at least had this in combination with snapshotting while
  		 * writing large files.
  		 */
  		ret = 0;
  		goto out;
  	}
  
  	fi = btrfs_item_ptr(eb, path->slots[0],
  			struct btrfs_file_extent_item);
  	extent_type = btrfs_file_extent_type(eb, fi);
  	if (extent_type == BTRFS_FILE_EXTENT_INLINE) {
  		ret = -ENOENT;
  		goto out;
  	}
  	compressed = btrfs_file_extent_compression(eb, fi);
  
  	num_bytes = btrfs_file_extent_num_bytes(eb, fi);
  	disk_byte = btrfs_file_extent_disk_bytenr(eb, fi);
  	if (disk_byte == 0) {
  		ret = -ENOENT;
  		goto out;
  	}
  	logical = disk_byte + btrfs_file_extent_offset(eb, fi);
  
  	down_read(&sctx->send_root->fs_info->commit_root_sem);
  	ret = extent_from_logical(sctx->send_root->fs_info, disk_byte, tmp_path,
  				  &found_key, &flags);
  	up_read(&sctx->send_root->fs_info->commit_root_sem);
  	btrfs_release_path(tmp_path);
  
  	if (ret < 0)
  		goto out;
  	if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
  		ret = -EIO;
  		goto out;
  	}
  
  	/*
  	 * Setup the clone roots.
  	 */
  	for (i = 0; i < sctx->clone_roots_cnt; i++) {
  		cur_clone_root = sctx->clone_roots + i;
  		cur_clone_root->ino = (u64)-1;
  		cur_clone_root->offset = 0;
  		cur_clone_root->found_refs = 0;
  	}
  
  	backref_ctx->sctx = sctx;
  	backref_ctx->found = 0;
  	backref_ctx->cur_objectid = ino;
  	backref_ctx->cur_offset = data_offset;
  	backref_ctx->found_itself = 0;
  	backref_ctx->extent_len = num_bytes;
  	/*
  	 * For non-compressed extents iterate_extent_inodes() gives us extent
  	 * offsets that already take into account the data offset, but not for
  	 * compressed extents, since the offset is logical and not relative to
  	 * the physical extent locations. We must take this into account to
  	 * avoid sending clone offsets that go beyond the source file's size,
  	 * which would result in the clone ioctl failing with -EINVAL on the
  	 * receiving end.
  	 */
  	if (compressed == BTRFS_COMPRESS_NONE)
  		backref_ctx->data_offset = 0;
  	else
  		backref_ctx->data_offset = btrfs_file_extent_offset(eb, fi);
  
  	/*
  	 * The last extent of a file may be too large due to page alignment.
  	 * We need to adjust extent_len in this case so that the checks in
  	 * __iterate_backrefs work.
  	 */
  	if (data_offset + num_bytes >= ino_size)
  		backref_ctx->extent_len = ino_size - data_offset;
  
  	/*
  	 * Now collect all backrefs.
  	 */
  	if (compressed == BTRFS_COMPRESS_NONE)
  		extent_item_pos = logical - found_key.objectid;
  	else
  		extent_item_pos = 0;
  	ret = iterate_extent_inodes(sctx->send_root->fs_info,
  					found_key.objectid, extent_item_pos, 1,
  					__iterate_backrefs, backref_ctx);
  
  	if (ret < 0)
  		goto out;
  
  	if (!backref_ctx->found_itself) {
  		/* found a bug in backref code? */
  		ret = -EIO;
  		btrfs_err(sctx->send_root->fs_info, "did not find backref in "
  				"send_root. inode=%llu, offset=%llu, "
  				"disk_byte=%llu found extent=%llu",
  				ino, data_offset, disk_byte, found_key.objectid);
  		goto out;
  	}
  
  verbose_printk(KERN_DEBUG "btrfs: find_extent_clone: data_offset=%llu, "
  		"ino=%llu, "
  		"num_bytes=%llu, logical=%llu\n",
  		data_offset, ino, num_bytes, logical);
  
  	if (!backref_ctx->found)
  		verbose_printk("btrfs:    no clones found\n");
  
  	cur_clone_root = NULL;
  	for (i = 0; i < sctx->clone_roots_cnt; i++) {
  		if (sctx->clone_roots[i].found_refs) {
  			if (!cur_clone_root)
  				cur_clone_root = sctx->clone_roots + i;
  			else if (sctx->clone_roots[i].root == sctx->send_root)
  				/* prefer clones from send_root over others */
  				cur_clone_root = sctx->clone_roots + i;
  		}
  
  	}
  
  	if (cur_clone_root) {
  		*found = cur_clone_root;
  		ret = 0;
  	} else {
  		ret = -ENOENT;
  	}
  
  out:
  	btrfs_free_path(tmp_path);
  	kfree(backref_ctx);
  	return ret;
  }
  
  static int read_symlink(struct btrfs_root *root,
  			u64 ino,
  			struct fs_path *dest)
  {
  	int ret;
  	struct btrfs_path *path;
  	struct btrfs_key key;
  	struct btrfs_file_extent_item *ei;
  	u8 type;
  	u8 compression;
  	unsigned long off;
  	int len;
  
  	path = alloc_path_for_send();
  	if (!path)
  		return -ENOMEM;
  
  	key.objectid = ino;
  	key.type = BTRFS_EXTENT_DATA_KEY;
  	key.offset = 0;
  	ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
  	if (ret < 0)
  		goto out;
  	BUG_ON(ret);
  
  	ei = btrfs_item_ptr(path->nodes[0], path->slots[0],
  			struct btrfs_file_extent_item);
  	type = btrfs_file_extent_type(path->nodes[0], ei);
  	compression = btrfs_file_extent_compression(path->nodes[0], ei);
  	BUG_ON(type != BTRFS_FILE_EXTENT_INLINE);
  	BUG_ON(compression);
  
  	off = btrfs_file_extent_inline_start(ei);
  	len = btrfs_file_extent_inline_len(path->nodes[0], path->slots[0], ei);
  
  	ret = fs_path_add_from_extent_buffer(dest, path->nodes[0], off, len);
  
  out:
  	btrfs_free_path(path);
  	return ret;
  }
  
  /*
   * Helper function to generate a file name that is unique in the root of
   * send_root and parent_root. This is used to generate names for orphan inodes.
   */
  static int gen_unique_name(struct send_ctx *sctx,
  			   u64 ino, u64 gen,
  			   struct fs_path *dest)
  {
  	int ret = 0;
  	struct btrfs_path *path;
  	struct btrfs_dir_item *di;
  	char tmp[64];
  	int len;
  	u64 idx = 0;
  
  	path = alloc_path_for_send();
  	if (!path)
  		return -ENOMEM;
  
  	while (1) {
  		len = snprintf(tmp, sizeof(tmp), "o%llu-%llu-%llu",
  				ino, gen, idx);
  		ASSERT(len < sizeof(tmp));
  
  		di = btrfs_lookup_dir_item(NULL, sctx->send_root,
  				path, BTRFS_FIRST_FREE_OBJECTID,
  				tmp, strlen(tmp), 0);
  		btrfs_release_path(path);
  		if (IS_ERR(di)) {
  			ret = PTR_ERR(di);
  			goto out;
  		}
  		if (di) {
  			/* not unique, try again */
  			idx++;
  			continue;
  		}
  
  		if (!sctx->parent_root) {
  			/* unique */
  			ret = 0;
  			break;
  		}
  
  		di = btrfs_lookup_dir_item(NULL, sctx->parent_root,
  				path, BTRFS_FIRST_FREE_OBJECTID,
  				tmp, strlen(tmp), 0);
  		btrfs_release_path(path);
  		if (IS_ERR(di)) {
  			ret = PTR_ERR(di);
  			goto out;
  		}
  		if (di) {
  			/* not unique, try again */
  			idx++;
  			continue;
  		}
  		/* unique */
  		break;
  	}
  
  	ret = fs_path_add(dest, tmp, strlen(tmp));
  
  out:
  	btrfs_free_path(path);
  	return ret;
  }
  
  enum inode_state {
  	inode_state_no_change,
  	inode_state_will_create,
  	inode_state_did_create,
  	inode_state_will_delete,
  	inode_state_did_delete,
  };
  
  static int get_cur_inode_state(struct send_ctx *sctx, u64 ino, u64 gen)
  {
  	int ret;
  	int left_ret;
  	int right_ret;
  	u64 left_gen;
  	u64 right_gen;
  
  	ret = get_inode_info(sctx->send_root, ino, NULL, &left_gen, NULL, NULL,
  			NULL, NULL);
  	if (ret < 0 && ret != -ENOENT)
  		goto out;
  	left_ret = ret;
  
  	if (!sctx->parent_root) {
  		right_ret = -ENOENT;
  	} else {
  		ret = get_inode_info(sctx->parent_root, ino, NULL, &right_gen,
  				NULL, NULL, NULL, NULL);
  		if (ret < 0 && ret != -ENOENT)
  			goto out;
  		right_ret = ret;
  	}
  
  	if (!left_ret && !right_ret) {
  		if (left_gen == gen && right_gen == gen) {
  			ret = inode_state_no_change;
  		} else if (left_gen == gen) {
  			if (ino < sctx->send_progress)
  				ret = inode_state_did_create;
  			else
  				ret = inode_state_will_create;
  		} else if (right_gen == gen) {
  			if (ino < sctx->send_progress)
  				ret = inode_state_did_delete;
  			else
  				ret = inode_state_will_delete;
  		} else  {
  			ret = -ENOENT;
  		}
  	} else if (!left_ret) {
  		if (left_gen == gen) {
  			if (ino < sctx->send_progress)
  				ret = inode_state_did_create;
  			else
  				ret = inode_state_will_create;
  		} else {
  			ret = -ENOENT;
  		}
  	} else if (!right_ret) {
  		if (right_gen == gen) {
  			if (ino < sctx->send_progress)
  				ret = inode_state_did_delete;
  			else
  				ret = inode_state_will_delete;
  		} else {
  			ret = -ENOENT;
  		}
  	} else {
  		ret = -ENOENT;
  	}
  
  out:
  	return ret;
  }
  
  static int is_inode_existent(struct send_ctx *sctx, u64 ino, u64 gen)
  {
  	int ret;
  
  	ret = get_cur_inode_state(sctx, ino, gen);
  	if (ret < 0)
  		goto out;
  
  	if (ret == inode_state_no_change ||
  	    ret == inode_state_did_create ||
  	    ret == inode_state_will_delete)
  		ret = 1;
  	else
  		ret = 0;
  
  out:
  	return ret;
  }
  
  /*
   * Helper function to lookup a dir item in a dir.
   */
  static int lookup_dir_item_inode(struct btrfs_root *root,
  				 u64 dir, const char *name, int name_len,
  				 u64 *found_inode,
  				 u8 *found_type)
  {
  	int ret = 0;
  	struct btrfs_dir_item *di;
  	struct btrfs_key key;
  	struct btrfs_path *path;
  
  	path = alloc_path_for_send();
  	if (!path)
  		return -ENOMEM;
  
  	di = btrfs_lookup_dir_item(NULL, root, path,
  			dir, name, name_len, 0);
  	if (!di) {
  		ret = -ENOENT;
  		goto out;
  	}
  	if (IS_ERR(di)) {
  		ret = PTR_ERR(di);
  		goto out;
  	}
  	btrfs_dir_item_key_to_cpu(path->nodes[0], di, &key);
  	if (key.type == BTRFS_ROOT_ITEM_KEY) {
  		ret = -ENOENT;
  		goto out;
  	}
  	*found_inode = key.objectid;
  	*found_type = btrfs_dir_type(path->nodes[0], di);
  
  out:
  	btrfs_free_path(path);
  	return ret;
  }
  
  /*
   * Looks up the first btrfs_inode_ref of a given ino. It returns the parent dir,
   * generation of the parent dir and the name of the dir entry.
   */
  static int get_first_ref(struct btrfs_root *root, u64 ino,
  			 u64 *dir, u64 *dir_gen, struct fs_path *name)
  {
  	int ret;
  	struct btrfs_key key;
  	struct btrfs_key found_key;
  	struct btrfs_path *path;
  	int len;
  	u64 parent_dir;
  
  	path = alloc_path_for_send();
  	if (!path)
  		return -ENOMEM;
  
  	key.objectid = ino;
  	key.type = BTRFS_INODE_REF_KEY;
  	key.offset = 0;
  
  	ret = btrfs_search_slot_for_read(root, &key, path, 1, 0);
  	if (ret < 0)
  		goto out;
  	if (!ret)
  		btrfs_item_key_to_cpu(path->nodes[0], &found_key,
  				path->slots[0]);
  	if (ret || found_key.objectid != ino ||
  	    (found_key.type != BTRFS_INODE_REF_KEY &&
  	     found_key.type != BTRFS_INODE_EXTREF_KEY)) {
  		ret = -ENOENT;
  		goto out;
  	}
  
  	if (found_key.type == BTRFS_INODE_REF_KEY) {
  		struct btrfs_inode_ref *iref;
  		iref = btrfs_item_ptr(path->nodes[0], path->slots[0],
  				      struct btrfs_inode_ref);
  		len = btrfs_inode_ref_name_len(path->nodes[0], iref);
  		ret = fs_path_add_from_extent_buffer(name, path->nodes[0],
  						     (unsigned long)(iref + 1),
  						     len);
  		parent_dir = found_key.offset;
  	} else {
  		struct btrfs_inode_extref *extref;
  		extref = btrfs_item_ptr(path->nodes[0], path->slots[0],
  					struct btrfs_inode_extref);
  		len = btrfs_inode_extref_name_len(path->nodes[0], extref);
  		ret = fs_path_add_from_extent_buffer(name, path->nodes[0],
  					(unsigned long)&extref->name, len);
  		parent_dir = btrfs_inode_extref_parent(path->nodes[0], extref);
  	}
  	if (ret < 0)
  		goto out;
  	btrfs_release_path(path);
  
  	if (dir_gen) {
  		ret = get_inode_info(root, parent_dir, NULL, dir_gen, NULL,
  				     NULL, NULL, NULL);
  		if (ret < 0)
  			goto out;
  	}
  
  	*dir = parent_dir;
  
  out:
  	btrfs_free_path(path);
  	return ret;
  }
  
  static int is_first_ref(struct btrfs_root *root,
  			u64 ino, u64 dir,
  			const char *name, int name_len)
  {
  	int ret;
  	struct fs_path *tmp_name;
  	u64 tmp_dir;
  
  	tmp_name = fs_path_alloc();
  	if (!tmp_name)
  		return -ENOMEM;
  
  	ret = get_first_ref(root, ino, &tmp_dir, NULL, tmp_name);
  	if (ret < 0)
  		goto out;
  
  	if (dir != tmp_dir || name_len != fs_path_len(tmp_name)) {
  		ret = 0;
  		goto out;
  	}
  
  	ret = !memcmp(tmp_name->start, name, name_len);
  
  out:
  	fs_path_free(tmp_name);
  	return ret;
  }
  
  /*
   * Used by process_recorded_refs to determine if a new ref would overwrite an
   * already existing ref. In case it detects an overwrite, it returns the
   * inode/gen in who_ino/who_gen.
   * When an overwrite is detected, process_recorded_refs does proper orphanizing
   * to make sure later references to the overwritten inode are possible.
   * Orphanizing is however only required for the first ref of an inode.
   * process_recorded_refs does an additional is_first_ref check to see if
   * orphanizing is really required.
   */
  static int will_overwrite_ref(struct send_ctx *sctx, u64 dir, u64 dir_gen,
  			      const char *name, int name_len,
  			      u64 *who_ino, u64 *who_gen)
  {
  	int ret = 0;
  	u64 gen;
  	u64 other_inode = 0;
  	u8 other_type = 0;
  
  	if (!sctx->parent_root)
  		goto out;
  
  	ret = is_inode_existent(sctx, dir, dir_gen);
  	if (ret <= 0)
  		goto out;
  
  	/*
  	 * If we have a parent root we need to verify that the parent dir was
  	 * not delted and then re-created, if it was then we have no overwrite
  	 * and we can just unlink this entry.
  	 */
  	if (sctx->parent_root) {
  		ret = get_inode_info(sctx->parent_root, dir, NULL, &gen, NULL,
  				     NULL, NULL, NULL);
  		if (ret < 0 && ret != -ENOENT)
  			goto out;
  		if (ret) {
  			ret = 0;
  			goto out;
  		}
  		if (gen != dir_gen)
  			goto out;
  	}
  
  	ret = lookup_dir_item_inode(sctx->parent_root, dir, name, name_len,
  			&other_inode, &other_type);
  	if (ret < 0 && ret != -ENOENT)
  		goto out;
  	if (ret) {
  		ret = 0;
  		goto out;
  	}
  
  	/*
  	 * Check if the overwritten ref was already processed. If yes, the ref
  	 * was already unlinked/moved, so we can safely assume that we will not
  	 * overwrite anything at this point in time.
  	 */
  	if (other_inode > sctx->send_progress) {
  		ret = get_inode_info(sctx->parent_root, other_inode, NULL,
  				who_gen, NULL, NULL, NULL, NULL);
  		if (ret < 0)
  			goto out;
  
  		ret = 1;
  		*who_ino = other_inode;
  	} else {
  		ret = 0;
  	}
  
  out:
  	return ret;
  }
  
  /*
   * Checks if the ref was overwritten by an already processed inode. This is
   * used by __get_cur_name_and_parent to find out if the ref was orphanized and
   * thus the orphan name needs be used.
   * process_recorded_refs also uses it to avoid unlinking of refs that were
   * overwritten.
   */
  static int did_overwrite_ref(struct send_ctx *sctx,
  			    u64 dir, u64 dir_gen,
  			    u64 ino, u64 ino_gen,
  			    const char *name, int name_len)
  {
  	int ret = 0;
  	u64 gen;
  	u64 ow_inode;
  	u8 other_type;
  
  	if (!sctx->parent_root)
  		goto out;
  
  	ret = is_inode_existent(sctx, dir, dir_gen);
  	if (ret <= 0)
  		goto out;
  
  	/* check if the ref was overwritten by another ref */
  	ret = lookup_dir_item_inode(sctx->send_root, dir, name, name_len,
  			&ow_inode, &other_type);
  	if (ret < 0 && ret != -ENOENT)
  		goto out;
  	if (ret) {
  		/* was never and will never be overwritten */
  		ret = 0;
  		goto out;
  	}
  
  	ret = get_inode_info(sctx->send_root, ow_inode, NULL, &gen, NULL, NULL,
  			NULL, NULL);
  	if (ret < 0)
  		goto out;
  
  	if (ow_inode == ino && gen == ino_gen) {
  		ret = 0;
  		goto out;
  	}
  
  	/*
  	 * We know that it is or will be overwritten. Check this now.
  	 * The current inode being processed might have been the one that caused
  	 * inode 'ino' to be orphanized, therefore check if ow_inode matches
  	 * the current inode being processed.
  	 */
  	if ((ow_inode < sctx->send_progress) ||
  	    (ino != sctx->cur_ino && ow_inode == sctx->cur_ino &&
  	     gen == sctx->cur_inode_gen))
  		ret = 1;
  	else
  		ret = 0;
  
  out:
  	return ret;
  }
  
  /*
   * Same as did_overwrite_ref, but also checks if it is the first ref of an inode
   * that got overwritten. This is used by process_recorded_refs to determine
   * if it has to use the path as returned by get_cur_path or the orphan name.
   */
  static int did_overwrite_first_ref(struct send_ctx *sctx, u64 ino, u64 gen)
  {
  	int ret = 0;
  	struct fs_path *name = NULL;
  	u64 dir;
  	u64 dir_gen;
  
  	if (!sctx->parent_root)
  		goto out;
  
  	name = fs_path_alloc();
  	if (!name)
  		return -ENOMEM;
  
  	ret = get_first_ref(sctx->parent_root, ino, &dir, &dir_gen, name);
  	if (ret < 0)
  		goto out;
  
  	ret = did_overwrite_ref(sctx, dir, dir_gen, ino, gen,
  			name->start, fs_path_len(name));
  
  out:
  	fs_path_free(name);
  	return ret;
  }
  
  /*
   * Insert a name cache entry. On 32bit kernels the radix tree index is 32bit,
   * so we need to do some special handling in case we have clashes. This function
   * takes care of this with the help of name_cache_entry::radix_list.
   * In case of error, nce is kfreed.
   */
  static int name_cache_insert(struct send_ctx *sctx,
  			     struct name_cache_entry *nce)
  {
  	int ret = 0;
  	struct list_head *nce_head;
  
  	nce_head = radix_tree_lookup(&sctx->name_cache,
  			(unsigned long)nce->ino);
  	if (!nce_head) {
  		nce_head = kmalloc(sizeof(*nce_head), GFP_NOFS);
  		if (!nce_head) {
  			kfree(nce);
  			return -ENOMEM;
  		}
  		INIT_LIST_HEAD(nce_head);
  
  		ret = radix_tree_insert(&sctx->name_cache, nce->ino, nce_head);
  		if (ret < 0) {
  			kfree(nce_head);
  			kfree(nce);
  			return ret;
  		}
  	}
  	list_add_tail(&nce->radix_list, nce_head);
  	list_add_tail(&nce->list, &sctx->name_cache_list);
  	sctx->name_cache_size++;
  
  	return ret;
  }
  
  static void name_cache_delete(struct send_ctx *sctx,
  			      struct name_cache_entry *nce)
  {
  	struct list_head *nce_head;
  
  	nce_head = radix_tree_lookup(&sctx->name_cache,
  			(unsigned long)nce->ino);
  	if (!nce_head) {
  		btrfs_err(sctx->send_root->fs_info,
  	      "name_cache_delete lookup failed ino %llu cache size %d, leaking memory",
  			nce->ino, sctx->name_cache_size);
  	}
  
  	list_del(&nce->radix_list);
  	list_del(&nce->list);
  	sctx->name_cache_size--;
  
  	/*
  	 * We may not get to the final release of nce_head if the lookup fails
  	 */
  	if (nce_head && list_empty(nce_head)) {
  		radix_tree_delete(&sctx->name_cache, (unsigned long)nce->ino);
  		kfree(nce_head);
  	}
  }
  
  static struct name_cache_entry *name_cache_search(struct send_ctx *sctx,
  						    u64 ino, u64 gen)
  {
  	struct list_head *nce_head;
  	struct name_cache_entry *cur;
  
  	nce_head = radix_tree_lookup(&sctx->name_cache, (unsigned long)ino);
  	if (!nce_head)
  		return NULL;
  
  	list_for_each_entry(cur, nce_head, radix_list) {
  		if (cur->ino == ino && cur->gen == gen)
  			return cur;
  	}
  	return NULL;
  }
  
  /*
   * Removes the entry from the list and adds it back to the end. This marks the
   * entry as recently used so that name_cache_clean_unused does not remove it.
   */
  static void name_cache_used(struct send_ctx *sctx, struct name_cache_entry *nce)
  {
  	list_del(&nce->list);
  	list_add_tail(&nce->list, &sctx->name_cache_list);
  }
  
  /*
   * Remove some entries from the beginning of name_cache_list.
   */
  static void name_cache_clean_unused(struct send_ctx *sctx)
  {
  	struct name_cache_entry *nce;
  
  	if (sctx->name_cache_size < SEND_CTX_NAME_CACHE_CLEAN_SIZE)
  		return;
  
  	while (sctx->name_cache_size > SEND_CTX_MAX_NAME_CACHE_SIZE) {
  		nce = list_entry(sctx->name_cache_list.next,
  				struct name_cache_entry, list);
  		name_cache_delete(sctx, nce);
  		kfree(nce);
  	}
  }
  
  static void name_cache_free(struct send_ctx *sctx)
  {
  	struct name_cache_entry *nce;
  
  	while (!list_empty(&sctx->name_cache_list)) {
  		nce = list_entry(sctx->name_cache_list.next,
  				struct name_cache_entry, list);
  		name_cache_delete(sctx, nce);
  		kfree(nce);
  	}
  }
  
  /*
   * Used by get_cur_path for each ref up to the root.
   * Returns 0 if it succeeded.
   * Returns 1 if the inode is not existent or got overwritten. In that case, the
   * name is an orphan name. This instructs get_cur_path to stop iterating. If 1
   * is returned, parent_ino/parent_gen are not guaranteed to be valid.
   * Returns <0 in case of error.
   */
  static int __get_cur_name_and_parent(struct send_ctx *sctx,
  				     u64 ino, u64 gen,
  				     u64 *parent_ino,
  				     u64 *parent_gen,
  				     struct fs_path *dest)
  {
  	int ret;
  	int nce_ret;
  	struct name_cache_entry *nce = NULL;
  
  	/*
  	 * First check if we already did a call to this function with the same
  	 * ino/gen. If yes, check if the cache entry is still up-to-date. If yes
  	 * return the cached result.
  	 */
  	nce = name_cache_search(sctx, ino, gen);
  	if (nce) {
  		if (ino < sctx->send_progress && nce->need_later_update) {
  			name_cache_delete(sctx, nce);
  			kfree(nce);
  			nce = NULL;
  		} else {
  			name_cache_used(sctx, nce);
  			*parent_ino = nce->parent_ino;
  			*parent_gen = nce->parent_gen;
  			ret = fs_path_add(dest, nce->name, nce->name_len);
  			if (ret < 0)
  				goto out;
  			ret = nce->ret;
  			goto out;
  		}
  	}
  
  	/*
  	 * If the inode is not existent yet, add the orphan name and return 1.
  	 * This should only happen for the parent dir that we determine in
  	 * __record_new_ref
  	 */
  	ret = is_inode_existent(sctx, ino, gen);
  	if (ret < 0)
  		goto out;
  
  	if (!ret) {
  		ret = gen_unique_name(sctx, ino, gen, dest);
  		if (ret < 0)
  			goto out;
  		ret = 1;
  		goto out_cache;
  	}
  
  	/*
  	 * Depending on whether the inode was already processed or not, use
  	 * send_root or parent_root for ref lookup.
  	 */
  	if (ino < sctx->send_progress)
  		ret = get_first_ref(sctx->send_root, ino,
  				    parent_ino, parent_gen, dest);
  	else
  		ret = get_first_ref(sctx->parent_root, ino,
  				    parent_ino, parent_gen, dest);
  	if (ret < 0)
  		goto out;
  
  	/*
  	 * Check if the ref was overwritten by an inode's ref that was processed
  	 * earlier. If yes, treat as orphan and return 1.
  	 */
  	ret = did_overwrite_ref(sctx, *parent_ino, *parent_gen, ino, gen,
  			dest->start, dest->end - dest->start);
  	if (ret < 0)
  		goto out;
  	if (ret) {
  		fs_path_reset(dest);
  		ret = gen_unique_name(sctx, ino, gen, dest);
  		if (ret < 0)
  			goto out;
  		ret = 1;
  	}
  
  out_cache:
  	/*
  	 * Store the result of the lookup in the name cache.
  	 */
  	nce = kmalloc(sizeof(*nce) + fs_path_len(dest) + 1, GFP_NOFS);
  	if (!nce) {
  		ret = -ENOMEM;
  		goto out;
  	}
  
  	nce->ino = ino;
  	nce->gen = gen;
  	nce->parent_ino = *parent_ino;
  	nce->parent_gen = *parent_gen;
  	nce->name_len = fs_path_len(dest);
  	nce->ret = ret;
  	strcpy(nce->name, dest->start);
  
  	if (ino < sctx->send_progress)
  		nce->need_later_update = 0;
  	else
  		nce->need_later_update = 1;
  
  	nce_ret = name_cache_insert(sctx, nce);
  	if (nce_ret < 0)
  		ret = nce_ret;
  	name_cache_clean_unused(sctx);
  
  out:
  	return ret;
  }
  
  /*
   * Magic happens here. This function returns the first ref to an inode as it
   * would look like while receiving the stream at this point in time.
   * We walk the path up to the root. For every inode in between, we check if it
   * was already processed/sent. If yes, we continue with the parent as found
   * in send_root. If not, we continue with the parent as found in parent_root.
   * If we encounter an inode that was deleted at this point in time, we use the
   * inodes "orphan" name instead of the real name and stop. Same with new inodes
   * that were not created yet and overwritten inodes/refs.
   *
   * When do we have have orphan inodes:
   * 1. When an inode is freshly created and thus no valid refs are available yet
   * 2. When a directory lost all it's refs (deleted) but still has dir items
   *    inside which were not processed yet (pending for move/delete). If anyone
   *    tried to get the path to the dir items, it would get a path inside that
   *    orphan directory.
   * 3. When an inode is moved around or gets new links, it may overwrite the ref
   *    of an unprocessed inode. If in that case the first ref would be
   *    overwritten, the overwritten inode gets "orphanized". Later when we
   *    process this overwritten inode, it is restored at a new place by moving
   *    the orphan inode.
   *
   * sctx->send_progress tells this function at which point in time receiving
   * would be.
   */
  static int get_cur_path(struct send_ctx *sctx, u64 ino, u64 gen,
  			struct fs_path *dest)
  {
  	int ret = 0;
  	struct fs_path *name = NULL;
  	u64 parent_inode = 0;
  	u64 parent_gen = 0;
  	int stop = 0;
  
  	name = fs_path_alloc();
  	if (!name) {
  		ret = -ENOMEM;
  		goto out;
  	}
  
  	dest->reversed = 1;
  	fs_path_reset(dest);
  
  	while (!stop && ino != BTRFS_FIRST_FREE_OBJECTID) {
  		struct waiting_dir_move *wdm;
  
  		fs_path_reset(name);
  
  		if (is_waiting_for_rm(sctx, ino)) {
  			ret = gen_unique_name(sctx, ino, gen, name);
  			if (ret < 0)
  				goto out;
  			ret = fs_path_add_path(dest, name);
  			break;
  		}
  
  		wdm = get_waiting_dir_move(sctx, ino);
  		if (wdm && wdm->orphanized) {
  			ret = gen_unique_name(sctx, ino, gen, name);
  			stop = 1;
  		} else if (wdm) {
  			ret = get_first_ref(sctx->parent_root, ino,
  					    &parent_inode, &parent_gen, name);
  		} else {
  			ret = __get_cur_name_and_parent(sctx, ino, gen,
  							&parent_inode,
  							&parent_gen, name);
  			if (ret)
  				stop = 1;
  		}
  
  		if (ret < 0)
  			goto out;
  
  		ret = fs_path_add_path(dest, name);
  		if (ret < 0)
  			goto out;
  
  		ino = parent_inode;
  		gen = parent_gen;
  	}
  
  out:
  	fs_path_free(name);
  	if (!ret)
  		fs_path_unreverse(dest);
  	return ret;
  }
  
  /*
   * Sends a BTRFS_SEND_C_SUBVOL command/item to userspace
   */
  static int send_subvol_begin(struct send_ctx *sctx)
  {
  	int ret;
  	struct btrfs_root *send_root = sctx->send_root;
  	struct btrfs_root *parent_root = sctx->parent_root;
  	struct btrfs_path *path;
  	struct btrfs_key key;
  	struct btrfs_root_ref *ref;
  	struct extent_buffer *leaf;
  	char *name = NULL;
  	int namelen;
  
  	path = btrfs_alloc_path();
  	if (!path)
  		return -ENOMEM;
  
  	name = kmalloc(BTRFS_PATH_NAME_MAX, GFP_NOFS);
  	if (!name) {
  		btrfs_free_path(path);
  		return -ENOMEM;
  	}
  
  	key.objectid = send_root->objectid;
  	key.type = BTRFS_ROOT_BACKREF_KEY;
  	key.offset = 0;
  
  	ret = btrfs_search_slot_for_read(send_root->fs_info->tree_root,
  				&key, path, 1, 0);
  	if (ret < 0)
  		goto out;
  	if (ret) {
  		ret = -ENOENT;
  		goto out;
  	}
  
  	leaf = path->nodes[0];
  	btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
  	if (key.type != BTRFS_ROOT_BACKREF_KEY ||
  	    key.objectid != send_root->objectid) {
  		ret = -ENOENT;
  		goto out;
  	}
  	ref = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_root_ref);
  	namelen = btrfs_root_ref_name_len(leaf, ref);
  	read_extent_buffer(leaf, name, (unsigned long)(ref + 1), namelen);
  	btrfs_release_path(path);
  
  	if (parent_root) {
  		ret = begin_cmd(sctx, BTRFS_SEND_C_SNAPSHOT);
  		if (ret < 0)
  			goto out;
  	} else {
  		ret = begin_cmd(sctx, BTRFS_SEND_C_SUBVOL);
  		if (ret < 0)
  			goto out;
  	}
  
  	TLV_PUT_STRING(sctx, BTRFS_SEND_A_PATH, name, namelen);
  
  	if (!btrfs_is_empty_uuid(sctx->send_root->root_item.received_uuid))
  		TLV_PUT_UUID(sctx, BTRFS_SEND_A_UUID,
  			    sctx->send_root->root_item.received_uuid);
  	else
  		TLV_PUT_UUID(sctx, BTRFS_SEND_A_UUID,
  			    sctx->send_root->root_item.uuid);
  
  	TLV_PUT_U64(sctx, BTRFS_SEND_A_CTRANSID,
  		    le64_to_cpu(sctx->send_root->root_item.ctransid));
  	if (parent_root) {
  		if (!btrfs_is_empty_uuid(parent_root->root_item.received_uuid))
  			TLV_PUT_UUID(sctx, BTRFS_SEND_A_CLONE_UUID,
  				     parent_root->root_item.received_uuid);
  		else
  			TLV_PUT_UUID(sctx, BTRFS_SEND_A_CLONE_UUID,
  				     parent_root->root_item.uuid);
  		TLV_PUT_U64(sctx, BTRFS_SEND_A_CLONE_CTRANSID,
  			    le64_to_cpu(sctx->parent_root->root_item.ctransid));
  	}
  
  	ret = send_cmd(sctx);
  
  tlv_put_failure:
  out:
  	btrfs_free_path(path);
  	kfree(name);
  	return ret;
  }
  
  static int send_truncate(struct send_ctx *sctx, u64 ino, u64 gen, u64 size)
  {
  	int ret = 0;
  	struct fs_path *p;
  
  verbose_printk("btrfs: send_truncate %llu size=%llu\n", ino, size);
  
  	p = fs_path_alloc();
  	if (!p)
  		return -ENOMEM;
  
  	ret = begin_cmd(sctx, BTRFS_SEND_C_TRUNCATE);
  	if (ret < 0)
  		goto out;
  
  	ret = get_cur_path(sctx, ino, gen, p);
  	if (ret < 0)
  		goto out;
  	TLV_PUT_PATH(sctx, BTRFS_SEND_A_PATH, p);
  	TLV_PUT_U64(sctx, BTRFS_SEND_A_SIZE, size);
  
  	ret = send_cmd(sctx);
  
  tlv_put_failure:
  out:
  	fs_path_free(p);
  	return ret;
  }
  
  static int send_chmod(struct send_ctx *sctx, u64 ino, u64 gen, u64 mode)
  {
  	int ret = 0;
  	struct fs_path *p;
  
  verbose_printk("btrfs: send_chmod %llu mode=%llu\n", ino, mode);
  
  	p = fs_path_alloc();
  	if (!p)
  		return -ENOMEM;
  
  	ret = begin_cmd(sctx, BTRFS_SEND_C_CHMOD);
  	if (ret < 0)
  		goto out;
  
  	ret = get_cur_path(sctx, ino, gen, p);
  	if (ret < 0)
  		goto out;
  	TLV_PUT_PATH(sctx, BTRFS_SEND_A_PATH, p);
  	TLV_PUT_U64(sctx, BTRFS_SEND_A_MODE, mode & 07777);
  
  	ret = send_cmd(sctx);
  
  tlv_put_failure:
  out:
  	fs_path_free(p);
  	return ret;
  }
  
  static int send_chown(struct send_ctx *sctx, u64 ino, u64 gen, u64 uid, u64 gid)
  {
  	int ret = 0;
  	struct fs_path *p;
  
  verbose_printk("btrfs: send_chown %llu uid=%llu, gid=%llu\n", ino, uid, gid);
  
  	p = fs_path_alloc();
  	if (!p)
  		return -ENOMEM;
  
  	ret = begin_cmd(sctx, BTRFS_SEND_C_CHOWN);
  	if (ret < 0)
  		goto out;
  
  	ret = get_cur_path(sctx, ino, gen, p);
  	if (ret < 0)
  		goto out;
  	TLV_PUT_PATH(sctx, BTRFS_SEND_A_PATH, p);
  	TLV_PUT_U64(sctx, BTRFS_SEND_A_UID, uid);
  	TLV_PUT_U64(sctx, BTRFS_SEND_A_GID, gid);
  
  	ret = send_cmd(sctx);
  
  tlv_put_failure:
  out:
  	fs_path_free(p);
  	return ret;
  }
  
  static int send_utimes(struct send_ctx *sctx, u64 ino, u64 gen)
  {
  	int ret = 0;
  	struct fs_path *p = NULL;
  	struct btrfs_inode_item *ii;
  	struct btrfs_path *path = NULL;
  	struct extent_buffer *eb;
  	struct btrfs_key key;
  	int slot;
  
  verbose_printk("btrfs: send_utimes %llu\n", ino);
  
  	p = fs_path_alloc();
  	if (!p)
  		return -ENOMEM;
  
  	path = alloc_path_for_send();
  	if (!path) {
  		ret = -ENOMEM;
  		goto out;
  	}
  
  	key.objectid = ino;
  	key.type = BTRFS_INODE_ITEM_KEY;
  	key.offset = 0;
  	ret = btrfs_search_slot(NULL, sctx->send_root, &key, path, 0, 0);
  	if (ret < 0)
  		goto out;
  
  	eb = path->nodes[0];
  	slot = path->slots[0];
  	ii = btrfs_item_ptr(eb, slot, struct btrfs_inode_item);
  
  	ret = begin_cmd(sctx, BTRFS_SEND_C_UTIMES);
  	if (ret < 0)
  		goto out;
  
  	ret = get_cur_path(sctx, ino, gen, p);
  	if (ret < 0)
  		goto out;
  	TLV_PUT_PATH(sctx, BTRFS_SEND_A_PATH, p);
  	TLV_PUT_BTRFS_TIMESPEC(sctx, BTRFS_SEND_A_ATIME, eb, &ii->atime);
  	TLV_PUT_BTRFS_TIMESPEC(sctx, BTRFS_SEND_A_MTIME, eb, &ii->mtime);
  	TLV_PUT_BTRFS_TIMESPEC(sctx, BTRFS_SEND_A_CTIME, eb, &ii->ctime);
  	/* TODO Add otime support when the otime patches get into upstream */
  
  	ret = send_cmd(sctx);
  
  tlv_put_failure:
  out:
  	fs_path_free(p);
  	btrfs_free_path(path);
  	return ret;
  }
  
  /*
   * Sends a BTRFS_SEND_C_MKXXX or SYMLINK command to user space. We don't have
   * a valid path yet because we did not process the refs yet. So, the inode
   * is created as orphan.
   */
  static int send_create_inode(struct send_ctx *sctx, u64 ino)
  {
  	int ret = 0;
  	struct fs_path *p;
  	int cmd;
  	u64 gen;
  	u64 mode;
  	u64 rdev;
  
  verbose_printk("btrfs: send_create_inode %llu\n", ino);
  
  	p = fs_path_alloc();
  	if (!p)
  		return -ENOMEM;
  
  	if (ino != sctx->cur_ino) {
  		ret = get_inode_info(sctx->send_root, ino, NULL, &gen, &mode,
  				     NULL, NULL, &rdev);
  		if (ret < 0)
  			goto out;
  	} else {
  		gen = sctx->cur_inode_gen;
  		mode = sctx->cur_inode_mode;
  		rdev = sctx->cur_inode_rdev;
  	}
  
  	if (S_ISREG(mode)) {
  		cmd = BTRFS_SEND_C_MKFILE;
  	} else if (S_ISDIR(mode)) {
  		cmd = BTRFS_SEND_C_MKDIR;
  	} else if (S_ISLNK(mode)) {
  		cmd = BTRFS_SEND_C_SYMLINK;
  	} else if (S_ISCHR(mode) || S_ISBLK(mode)) {
  		cmd = BTRFS_SEND_C_MKNOD;
  	} else if (S_ISFIFO(mode)) {
  		cmd = BTRFS_SEND_C_MKFIFO;
  	} else if (S_ISSOCK(mode)) {
  		cmd = BTRFS_SEND_C_MKSOCK;
  	} else {
  		btrfs_warn(sctx->send_root->fs_info, "unexpected inode type %o",
  				(int)(mode & S_IFMT));
  		ret = -ENOTSUPP;
  		goto out;
  	}
  
  	ret = begin_cmd(sctx, cmd);
  	if (ret < 0)
  		goto out;
  
  	ret = gen_unique_name(sctx, ino, gen, p);
  	if (ret < 0)
  		goto out;
  
  	TLV_PUT_PATH(sctx, BTRFS_SEND_A_PATH, p);
  	TLV_PUT_U64(sctx, BTRFS_SEND_A_INO, ino);
  
  	if (S_ISLNK(mode)) {
  		fs_path_reset(p);
  		ret = read_symlink(sctx->send_root, ino, p);
  		if (ret < 0)
  			goto out;
  		TLV_PUT_PATH(sctx, BTRFS_SEND_A_PATH_LINK, p);
  	} else if (S_ISCHR(mode) || S_ISBLK(mode) ||
  		   S_ISFIFO(mode) || S_ISSOCK(mode)) {
  		TLV_PUT_U64(sctx, BTRFS_SEND_A_RDEV, new_encode_dev(rdev));
  		TLV_PUT_U64(sctx, BTRFS_SEND_A_MODE, mode);
  	}
  
  	ret = send_cmd(sctx);
  	if (ret < 0)
  		goto out;
  
  
  tlv_put_failure:
  out:
  	fs_path_free(p);
  	return ret;
  }
  
  /*
   * We need some special handling for inodes that get processed before the parent
   * directory got created. See process_recorded_refs for details.
   * This function does the check if we already created the dir out of order.
   */
  static int did_create_dir(struct send_ctx *sctx, u64 dir)
  {
  	int ret = 0;
  	struct btrfs_path *path = NULL;
  	struct btrfs_key key;
  	struct btrfs_key found_key;
  	struct btrfs_key di_key;
  	struct extent_buffer *eb;
  	struct btrfs_dir_item *di;
  	int slot;
  
  	path = alloc_path_for_send();
  	if (!path) {
  		ret = -ENOMEM;
  		goto out;
  	}
  
  	key.objectid = dir;
  	key.type = BTRFS_DIR_INDEX_KEY;
  	key.offset = 0;
  	ret = btrfs_search_slot(NULL, sctx->send_root, &key, path, 0, 0);
  	if (ret < 0)
  		goto out;
  
  	while (1) {
  		eb = path->nodes[0];
  		slot = path->slots[0];
  		if (slot >= btrfs_header_nritems(eb)) {
  			ret = btrfs_next_leaf(sctx->send_root, path);
  			if (ret < 0) {
  				goto out;
  			} else if (ret > 0) {
  				ret = 0;
  				break;
  			}
  			continue;
  		}
  
  		btrfs_item_key_to_cpu(eb, &found_key, slot);
  		if (found_key.objectid != key.objectid ||
  		    found_key.type != key.type) {
  			ret = 0;
  			goto out;
  		}
  
  		di = btrfs_item_ptr(eb, slot, struct btrfs_dir_item);
  		btrfs_dir_item_key_to_cpu(eb, di, &di_key);
  
  		if (di_key.type != BTRFS_ROOT_ITEM_KEY &&
  		    di_key.objectid < sctx->send_progress) {
  			ret = 1;
  			goto out;
  		}
  
  		path->slots[0]++;
  	}
  
  out:
  	btrfs_free_path(path);
  	return ret;
  }
  
  /*
   * Only creates the inode if it is:
   * 1. Not a directory
   * 2. Or a directory which was not created already due to out of order
   *    directories. See did_create_dir and process_recorded_refs for details.
   */
  static int send_create_inode_if_needed(struct send_ctx *sctx)
  {
  	int ret;
  
  	if (S_ISDIR(sctx->cur_inode_mode)) {
  		ret = did_create_dir(sctx, sctx->cur_ino);
  		if (ret < 0)
  			goto out;
  		if (ret) {
  			ret = 0;
  			goto out;
  		}
  	}
  
  	ret = send_create_inode(sctx, sctx->cur_ino);
  	if (ret < 0)
  		goto out;
  
  out:
  	return ret;
  }
  
  struct recorded_ref {
  	struct list_head list;
  	char *dir_path;
  	char *name;
  	struct fs_path *full_path;
  	u64 dir;
  	u64 dir_gen;
  	int dir_path_len;
  	int name_len;
  };
  
  /*
   * We need to process new refs before deleted refs, but compare_tree gives us
   * everything mixed. So we first record all refs and later process them.
   * This function is a helper to record one ref.
   */
  static int __record_ref(struct list_head *head, u64 dir,
  		      u64 dir_gen, struct fs_path *path)
  {
  	struct recorded_ref *ref;
  
  	ref = kmalloc(sizeof(*ref), GFP_NOFS);
  	if (!ref)
  		return -ENOMEM;
  
  	ref->dir = dir;
  	ref->dir_gen = dir_gen;
  	ref->full_path = path;
  
  	ref->name = (char *)kbasename(ref->full_path->start);
  	ref->name_len = ref->full_path->end - ref->name;
  	ref->dir_path = ref->full_path->start;
  	if (ref->name == ref->full_path->start)
  		ref->dir_path_len = 0;
  	else
  		ref->dir_path_len = ref->full_path->end -
  				ref->full_path->start - 1 - ref->name_len;
  
  	list_add_tail(&ref->list, head);
  	return 0;
  }
  
  static int dup_ref(struct recorded_ref *ref, struct list_head *list)
  {
  	struct recorded_ref *new;
  
  	new = kmalloc(sizeof(*ref), GFP_NOFS);
  	if (!new)
  		return -ENOMEM;
  
  	new->dir = ref->dir;
  	new->dir_gen = ref->dir_gen;
  	new->full_path = NULL;
  	INIT_LIST_HEAD(&new->list);
  	list_add_tail(&new->list, list);
  	return 0;
  }
  
  static void __free_recorded_refs(struct list_head *head)
  {
  	struct recorded_ref *cur;
  
  	while (!list_empty(head)) {
  		cur = list_entry(head->next, struct recorded_ref, list);
  		fs_path_free(cur->full_path);
  		list_del(&cur->list);
  		kfree(cur);
  	}
  }
  
  static void free_recorded_refs(struct send_ctx *sctx)
  {
  	__free_recorded_refs(&sctx->new_refs);
  	__free_recorded_refs(&sctx->deleted_refs);
  }
  
  /*
   * Renames/moves a file/dir to its orphan name. Used when the first
   * ref of an unprocessed inode gets overwritten and for all non empty
   * directories.
   */
  static int orphanize_inode(struct send_ctx *sctx, u64 ino, u64 gen,
  			  struct fs_path *path)
  {
  	int ret;
  	struct fs_path *orphan;
  
  	orphan = fs_path_alloc();
  	if (!orphan)
  		return -ENOMEM;
  
  	ret = gen_unique_name(sctx, ino, gen, orphan);
  	if (ret < 0)
  		goto out;
  
  	ret = send_rename(sctx, path, orphan);
  
  out:
  	fs_path_free(orphan);
  	return ret;
  }
  
  static struct orphan_dir_info *
  add_orphan_dir_info(struct send_ctx *sctx, u64 dir_ino)
  {
  	struct rb_node **p = &sctx->orphan_dirs.rb_node;
  	struct rb_node *parent = NULL;
  	struct orphan_dir_info *entry, *odi;
  
  	odi = kmalloc(sizeof(*odi), GFP_NOFS);
  	if (!odi)
  		return ERR_PTR(-ENOMEM);
  	odi->ino = dir_ino;
  	odi->gen = 0;
  
  	while (*p) {
  		parent = *p;
  		entry = rb_entry(parent, struct orphan_dir_info, node);
  		if (dir_ino < entry->ino) {
  			p = &(*p)->rb_left;
  		} else if (dir_ino > entry->ino) {
  			p = &(*p)->rb_right;
  		} else {
  			kfree(odi);
  			return entry;
  		}
  	}
  
  	rb_link_node(&odi->node, parent, p);
  	rb_insert_color(&odi->node, &sctx->orphan_dirs);
  	return odi;
  }
  
  static struct orphan_dir_info *
  get_orphan_dir_info(struct send_ctx *sctx, u64 dir_ino)
  {
  	struct rb_node *n = sctx->orphan_dirs.rb_node;
  	struct orphan_dir_info *entry;
  
  	while (n) {
  		entry = rb_entry(n, struct orphan_dir_info, node);
  		if (dir_ino < entry->ino)
  			n = n->rb_left;
  		else if (dir_ino > entry->ino)
  			n = n->rb_right;
  		else
  			return entry;
  	}
  	return NULL;
  }
  
  static int is_waiting_for_rm(struct send_ctx *sctx, u64 dir_ino)
  {
  	struct orphan_dir_info *odi = get_orphan_dir_info(sctx, dir_ino);
  
  	return odi != NULL;
  }
  
  static void free_orphan_dir_info(struct send_ctx *sctx,
  				 struct orphan_dir_info *odi)
  {
  	if (!odi)
  		return;
  	rb_erase(&odi->node, &sctx->orphan_dirs);
  	kfree(odi);
  }
  
  /*
   * Returns 1 if a directory can be removed at this point in time.
   * We check this by iterating all dir items and checking if the inode behind
   * the dir item was already processed.
   */
  static int can_rmdir(struct send_ctx *sctx, u64 dir, u64 dir_gen,
  		     u64 send_progress)
  {
  	int ret = 0;
  	struct btrfs_root *root = sctx->parent_root;
  	struct btrfs_path *path;
  	struct btrfs_key key;
  	struct btrfs_key found_key;
  	struct btrfs_key loc;
  	struct btrfs_dir_item *di;
  
  	/*
  	 * Don't try to rmdir the top/root subvolume dir.
  	 */
  	if (dir == BTRFS_FIRST_FREE_OBJECTID)
  		return 0;
  
  	path = alloc_path_for_send();
  	if (!path)
  		return -ENOMEM;
  
  	key.objectid = dir;
  	key.type = BTRFS_DIR_INDEX_KEY;
  	key.offset = 0;
  	ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
  	if (ret < 0)
  		goto out;
  
  	while (1) {
  		struct waiting_dir_move *dm;
  
  		if (path->slots[0] >= btrfs_header_nritems(path->nodes[0])) {
  			ret = btrfs_next_leaf(root, path);
  			if (ret < 0)
  				goto out;
  			else if (ret > 0)
  				break;
  			continue;
  		}
  		btrfs_item_key_to_cpu(path->nodes[0], &found_key,
  				      path->slots[0]);
  		if (found_key.objectid != key.objectid ||
  		    found_key.type != key.type)
  			break;
  
  		di = btrfs_item_ptr(path->nodes[0], path->slots[0],
  				struct btrfs_dir_item);
  		btrfs_dir_item_key_to_cpu(path->nodes[0], di, &loc);
  
  		dm = get_waiting_dir_move(sctx, loc.objectid);
  		if (dm) {
  			struct orphan_dir_info *odi;
  
  			odi = add_orphan_dir_info(sctx, dir);
  			if (IS_ERR(odi)) {
  				ret = PTR_ERR(odi);
  				goto out;
  			}
  			odi->gen = dir_gen;
  			dm->rmdir_ino = dir;
  			ret = 0;
  			goto out;
  		}
  
  		if (loc.objectid > send_progress) {
  			ret = 0;
  			goto out;
  		}
  
  		path->slots[0]++;
  	}
  
  	ret = 1;
  
  out:
  	btrfs_free_path(path);
  	return ret;
  }
  
  static int is_waiting_for_move(struct send_ctx *sctx, u64 ino)
  {
  	struct waiting_dir_move *entry = get_waiting_dir_move(sctx, ino);
  
  	return entry != NULL;
  }
  
  static int add_waiting_dir_move(struct send_ctx *sctx, u64 ino, bool orphanized)
  {
  	struct rb_node **p = &sctx->waiting_dir_moves.rb_node;
  	struct rb_node *parent = NULL;
  	struct waiting_dir_move *entry, *dm;
  
  	dm = kmalloc(sizeof(*dm), GFP_NOFS);
  	if (!dm)
  		return -ENOMEM;
  	dm->ino = ino;
  	dm->rmdir_ino = 0;
  	dm->orphanized = orphanized;
  
  	while (*p) {
  		parent = *p;
  		entry = rb_entry(parent, struct waiting_dir_move, node);
  		if (ino < entry->ino) {
  			p = &(*p)->rb_left;
  		} else if (ino > entry->ino) {
  			p = &(*p)->rb_right;
  		} else {
  			kfree(dm);
  			return -EEXIST;
  		}
  	}
  
  	rb_link_node(&dm->node, parent, p);
  	rb_insert_color(&dm->node, &sctx->waiting_dir_moves);
  	return 0;
  }
  
  static struct waiting_dir_move *
  get_waiting_dir_move(struct send_ctx *sctx, u64 ino)
  {
  	struct rb_node *n = sctx->waiting_dir_moves.rb_node;
  	struct waiting_dir_move *entry;
  
  	while (n) {
  		entry = rb_entry(n, struct waiting_dir_move, node);
  		if (ino < entry->ino)
  			n = n->rb_left;
  		else if (ino > entry->ino)
  			n = n->rb_right;
  		else
  			return entry;
  	}
  	return NULL;
  }
  
  static void free_waiting_dir_move(struct send_ctx *sctx,
  				  struct waiting_dir_move *dm)
  {
  	if (!dm)
  		return;
  	rb_erase(&dm->node, &sctx->waiting_dir_moves);
  	kfree(dm);
  }
  
  static int add_pending_dir_move(struct send_ctx *sctx,
  				u64 ino,
  				u64 ino_gen,
  				u64 parent_ino,
  				struct list_head *new_refs,
  				struct list_head *deleted_refs,
  				const bool is_orphan)
  {
  	struct rb_node **p = &sctx->pending_dir_moves.rb_node;
  	struct rb_node *parent = NULL;
  	struct pending_dir_move *entry = NULL, *pm;
  	struct recorded_ref *cur;
  	int exists = 0;
  	int ret;
  
  	pm = kmalloc(sizeof(*pm), GFP_NOFS);
  	if (!pm)
  		return -ENOMEM;
  	pm->parent_ino = parent_ino;
  	pm->ino = ino;
  	pm->gen = ino_gen;
  	pm->is_orphan = is_orphan;
  	INIT_LIST_HEAD(&pm->list);
  	INIT_LIST_HEAD(&pm->update_refs);
  	RB_CLEAR_NODE(&pm->node);
  
  	while (*p) {
  		parent = *p;
  		entry = rb_entry(parent, struct pending_dir_move, node);
  		if (parent_ino < entry->parent_ino) {
  			p = &(*p)->rb_left;
  		} else if (parent_ino > entry->parent_ino) {
  			p = &(*p)->rb_right;
  		} else {
  			exists = 1;
  			break;
  		}
  	}
  
  	list_for_each_entry(cur, deleted_refs, list) {
  		ret = dup_ref(cur, &pm->update_refs);
  		if (ret < 0)
  			goto out;
  	}
  	list_for_each_entry(cur, new_refs, list) {
  		ret = dup_ref(cur, &pm->update_refs);
  		if (ret < 0)
  			goto out;
  	}
  
  	ret = add_waiting_dir_move(sctx, pm->ino, is_orphan);
  	if (ret)
  		goto out;
  
  	if (exists) {
  		list_add_tail(&pm->list, &entry->list);
  	} else {
  		rb_link_node(&pm->node, parent, p);
  		rb_insert_color(&pm->node, &sctx->pending_dir_moves);
  	}
  	ret = 0;
  out:
  	if (ret) {
  		__free_recorded_refs(&pm->update_refs);
  		kfree(pm);
  	}
  	return ret;
  }
  
  static struct pending_dir_move *get_pending_dir_moves(struct send_ctx *sctx,
  						      u64 parent_ino)
  {
  	struct rb_node *n = sctx->pending_dir_moves.rb_node;
  	struct pending_dir_move *entry;
  
  	while (n) {
  		entry = rb_entry(n, struct pending_dir_move, node);
  		if (parent_ino < entry->parent_ino)
  			n = n->rb_left;
  		else if (parent_ino > entry->parent_ino)
  			n = n->rb_right;
  		else
  			return entry;
  	}
  	return NULL;
  }
  
  static int apply_dir_move(struct send_ctx *sctx, struct pending_dir_move *pm)
  {
  	struct fs_path *from_path = NULL;
  	struct fs_path *to_path = NULL;
  	struct fs_path *name = NULL;
  	u64 orig_progress = sctx->send_progress;
  	struct recorded_ref *cur;
  	u64 parent_ino, parent_gen;
  	struct waiting_dir_move *dm = NULL;
  	u64 rmdir_ino = 0;
  	int ret;
  
  	name = fs_path_alloc();
  	from_path = fs_path_alloc();
  	if (!name || !from_path) {
  		ret = -ENOMEM;
  		goto out;
  	}
  
  	dm = get_waiting_dir_move(sctx, pm->ino);
  	ASSERT(dm);
  	rmdir_ino = dm->rmdir_ino;
  	free_waiting_dir_move(sctx, dm);
  
  	if (pm->is_orphan) {
  		ret = gen_unique_name(sctx, pm->ino,
  				      pm->gen, from_path);
  	} else {
  		ret = get_first_ref(sctx->parent_root, pm->ino,
  				    &parent_ino, &parent_gen, name);
  		if (ret < 0)
  			goto out;
  		ret = get_cur_path(sctx, parent_ino, parent_gen,
  				   from_path);
  		if (ret < 0)
  			goto out;
  		ret = fs_path_add_path(from_path, name);
  	}
  	if (ret < 0)
  		goto out;
  
  	sctx->send_progress = sctx->cur_ino + 1;
  	fs_path_reset(name);
  	to_path = name;
  	name = NULL;
  	ret = get_cur_path(sctx, pm->ino, pm->gen, to_path);
  	if (ret < 0)
  		goto out;
  
  	ret = send_rename(sctx, from_path, to_path);
  	if (ret < 0)
  		goto out;
  
  	if (rmdir_ino) {
  		struct orphan_dir_info *odi;
  
  		odi = get_orphan_dir_info(sctx, rmdir_ino);
  		if (!odi) {
  			/* already deleted */
  			goto finish;
  		}
  		ret = can_rmdir(sctx, rmdir_ino, odi->gen, sctx->cur_ino + 1);
  		if (ret < 0)
  			goto out;
  		if (!ret)
  			goto finish;
  
  		name = fs_path_alloc();
  		if (!name) {
  			ret = -ENOMEM;
  			goto out;
  		}
  		ret = get_cur_path(sctx, rmdir_ino, odi->gen, name);
  		if (ret < 0)
  			goto out;
  		ret = send_rmdir(sctx, name);
  		if (ret < 0)
  			goto out;
  		free_orphan_dir_info(sctx, odi);
  	}
  
  finish:
  	ret = send_utimes(sctx, pm->ino, pm->gen);
  	if (ret < 0)
  		goto out;
  
  	/*
  	 * After rename/move, need to update the utimes of both new parent(s)
  	 * and old parent(s).
  	 */
  	list_for_each_entry(cur, &pm->update_refs, list) {
  		if (cur->dir == rmdir_ino)
  			continue;
  		ret = send_utimes(sctx, cur->dir, cur->dir_gen);
  		if (ret < 0)
  			goto out;
  	}
  
  out:
  	fs_path_free(name);
  	fs_path_free(from_path);
  	fs_path_free(to_path);
  	sctx->send_progress = orig_progress;
  
  	return ret;
  }
  
  static void free_pending_move(struct send_ctx *sctx, struct pending_dir_move *m)
  {
  	if (!list_empty(&m->list))
  		list_del(&m->list);
  	if (!RB_EMPTY_NODE(&m->node))
  		rb_erase(&m->node, &sctx->pending_dir_moves);
  	__free_recorded_refs(&m->update_refs);
  	kfree(m);
  }
  
  static void tail_append_pending_moves(struct pending_dir_move *moves,
  				      struct list_head *stack)
  {
  	if (list_empty(&moves->list)) {
  		list_add_tail(&moves->list, stack);
  	} else {
  		LIST_HEAD(list);
  		list_splice_init(&moves->list, &list);
  		list_add_tail(&moves->list, stack);
  		list_splice_tail(&list, stack);
  	}
  }
  
  static int apply_children_dir_moves(struct send_ctx *sctx)
  {
  	struct pending_dir_move *pm;
  	struct list_head stack;
  	u64 parent_ino = sctx->cur_ino;
  	int ret = 0;
  
  	pm = get_pending_dir_moves(sctx, parent_ino);
  	if (!pm)
  		return 0;
  
  	INIT_LIST_HEAD(&stack);
  	tail_append_pending_moves(pm, &stack);
  
  	while (!list_empty(&stack)) {
  		pm = list_first_entry(&stack, struct pending_dir_move, list);
  		parent_ino = pm->ino;
  		ret = apply_dir_move(sctx, pm);
  		free_pending_move(sctx, pm);
  		if (ret)
  			goto out;
  		pm = get_pending_dir_moves(sctx, parent_ino);
  		if (pm)
  			tail_append_pending_moves(pm, &stack);
  	}
  	return 0;
  
  out:
  	while (!list_empty(&stack)) {
  		pm = list_first_entry(&stack, struct pending_dir_move, list);
  		free_pending_move(sctx, pm);
  	}
  	return ret;
  }
  
  /*
   * We might need to delay a directory rename even when no ancestor directory
   * (in the send root) with a higher inode number than ours (sctx->cur_ino) was
   * renamed. This happens when we rename a directory to the old name (the name
   * in the parent root) of some other unrelated directory that got its rename
   * delayed due to some ancestor with higher number that got renamed.
   *
   * Example:
   *
   * Parent snapshot:
   * .                                       (ino 256)
   * |---- a/                                (ino 257)
   * |     |---- file                        (ino 260)
   * |
   * |---- b/                                (ino 258)
   * |---- c/                                (ino 259)
   *
   * Send snapshot:
   * .                                       (ino 256)
   * |---- a/                                (ino 258)
   * |---- x/                                (ino 259)
   *       |---- y/                          (ino 257)
   *             |----- file                 (ino 260)
   *
   * Here we can not rename 258 from 'b' to 'a' without the rename of inode 257
   * from 'a' to 'x/y' happening first, which in turn depends on the rename of
   * inode 259 from 'c' to 'x'. So the order of rename commands the send stream
   * must issue is:
   *
   * 1 - rename 259 from 'c' to 'x'
   * 2 - rename 257 from 'a' to 'x/y'
   * 3 - rename 258 from 'b' to 'a'
   *
   * Returns 1 if the rename of sctx->cur_ino needs to be delayed, 0 if it can
   * be done right away and < 0 on error.
   */
  static int wait_for_dest_dir_move(struct send_ctx *sctx,
  				  struct recorded_ref *parent_ref,
  				  const bool is_orphan)
  {
  	struct btrfs_path *path;
  	struct btrfs_key key;
  	struct btrfs_key di_key;
  	struct btrfs_dir_item *di;
  	u64 left_gen;
  	u64 right_gen;
  	int ret = 0;
  
  	if (RB_EMPTY_ROOT(&sctx->waiting_dir_moves))
  		return 0;
  
  	path = alloc_path_for_send();
  	if (!path)
  		return -ENOMEM;
  
  	key.objectid = parent_ref->dir;
  	key.type = BTRFS_DIR_ITEM_KEY;
  	key.offset = btrfs_name_hash(parent_ref->name, parent_ref->name_len);
  
  	ret = btrfs_search_slot(NULL, sctx->parent_root, &key, path, 0, 0);
  	if (ret < 0) {
  		goto out;
  	} else if (ret > 0) {
  		ret = 0;
  		goto out;
  	}
  
  	di = btrfs_match_dir_item_name(sctx->parent_root, path,
  				       parent_ref->name, parent_ref->name_len);
  	if (!di) {
  		ret = 0;
  		goto out;
  	}
  	/*
  	 * di_key.objectid has the number of the inode that has a dentry in the
  	 * parent directory with the same name that sctx->cur_ino is being
  	 * renamed to. We need to check if that inode is in the send root as
  	 * well and if it is currently marked as an inode with a pending rename,
  	 * if it is, we need to delay the rename of sctx->cur_ino as well, so
  	 * that it happens after that other inode is renamed.
  	 */
  	btrfs_dir_item_key_to_cpu(path->nodes[0], di, &di_key);
  	if (di_key.type != BTRFS_INODE_ITEM_KEY) {
  		ret = 0;
  		goto out;
  	}
  
  	ret = get_inode_info(sctx->parent_root, di_key.objectid, NULL,
  			     &left_gen, NULL, NULL, NULL, NULL);
  	if (ret < 0)
  		goto out;
  	ret = get_inode_info(sctx->send_root, di_key.objectid, NULL,
  			     &right_gen, NULL, NULL, NULL, NULL);
  	if (ret < 0) {
  		if (ret == -ENOENT)
  			ret = 0;
  		goto out;
  	}
  
  	/* Different inode, no need to delay the rename of sctx->cur_ino */
  	if (right_gen != left_gen) {
  		ret = 0;
  		goto out;
  	}
  
  	if (is_waiting_for_move(sctx, di_key.objectid)) {
  		ret = add_pending_dir_move(sctx,
  					   sctx->cur_ino,
  					   sctx->cur_inode_gen,
  					   di_key.objectid,
  					   &sctx->new_refs,
  					   &sctx->deleted_refs,
  					   is_orphan);
  		if (!ret)
  			ret = 1;
  	}
  out:
  	btrfs_free_path(path);
  	return ret;
  }
  
  /*
   * Check if ino ino1 is an ancestor of inode ino2 in the given root.
   * Return 1 if true, 0 if false and < 0 on error.
   */
  static int is_ancestor(struct btrfs_root *root,
  		       const u64 ino1,
  		       const u64 ino1_gen,
  		       const u64 ino2,
  		       struct fs_path *fs_path)
  {
  	u64 ino = ino2;
  
  	while (ino > BTRFS_FIRST_FREE_OBJECTID) {
  		int ret;
  		u64 parent;
  		u64 parent_gen;
  
  		fs_path_reset(fs_path);
  		ret = get_first_ref(root, ino, &parent, &parent_gen, fs_path);
  		if (ret < 0) {
  			if (ret == -ENOENT && ino == ino2)
  				ret = 0;
  			return ret;
  		}
  		if (parent == ino1)
  			return parent_gen == ino1_gen ? 1 : 0;
  		ino = parent;
  	}
  	return 0;
  }
  
  static int wait_for_parent_move(struct send_ctx *sctx,
  				struct recorded_ref *parent_ref,
  				const bool is_orphan)
  {
  	int ret = 0;
  	u64 ino = parent_ref->dir;
  	u64 parent_ino_before, parent_ino_after;
  	struct fs_path *path_before = NULL;
  	struct fs_path *path_after = NULL;
  	int len1, len2;
  
  	path_after = fs_path_alloc();
  	path_before = fs_path_alloc();
  	if (!path_after || !path_before) {
  		ret = -ENOMEM;
  		goto out;
  	}
  
  	/*
  	 * Our current directory inode may not yet be renamed/moved because some
  	 * ancestor (immediate or not) has to be renamed/moved first. So find if
  	 * such ancestor exists and make sure our own rename/move happens after
  	 * that ancestor is processed to avoid path build infinite loops (done
  	 * at get_cur_path()).
  	 */
  	while (ino > BTRFS_FIRST_FREE_OBJECTID) {
  		if (is_waiting_for_move(sctx, ino)) {
  			/*
  			 * If the current inode is an ancestor of ino in the
  			 * parent root, we need to delay the rename of the
  			 * current inode, otherwise don't delayed the rename
  			 * because we can end up with a circular dependency
  			 * of renames, resulting in some directories never
  			 * getting the respective rename operations issued in
  			 * the send stream or getting into infinite path build
  			 * loops.
  			 */
  			ret = is_ancestor(sctx->parent_root,
  					  sctx->cur_ino, sctx->cur_inode_gen,
  					  ino, path_before);
  			break;
  		}
  
  		fs_path_reset(path_before);
  		fs_path_reset(path_after);
  
  		ret = get_first_ref(sctx->send_root, ino, &parent_ino_after,
  				    NULL, path_after);
  		if (ret < 0)
  			goto out;
  		ret = get_first_ref(sctx->parent_root, ino, &parent_ino_before,
  				    NULL, path_before);
  		if (ret < 0 && ret != -ENOENT) {
  			goto out;
  		} else if (ret == -ENOENT) {
  			ret = 0;
  			break;
  		}
  
  		len1 = fs_path_len(path_before);
  		len2 = fs_path_len(path_after);
  		if (ino > sctx->cur_ino &&
  		    (parent_ino_before != parent_ino_after || len1 != len2 ||
  		     memcmp(path_before->start, path_after->start, len1))) {
  			ret = 1;
  			break;
  		}
  		ino = parent_ino_after;
  	}
  
  out:
  	fs_path_free(path_before);
  	fs_path_free(path_after);
  
  	if (ret == 1) {
  		ret = add_pending_dir_move(sctx,
  					   sctx->cur_ino,
  					   sctx->cur_inode_gen,
  					   ino,
  					   &sctx->new_refs,
  					   &sctx->deleted_refs,
  					   is_orphan);
  		if (!ret)
  			ret = 1;
  	}
  
  	return ret;
  }
  
  /*
   * This does all the move/link/unlink/rmdir magic.
   */
  static int process_recorded_refs(struct send_ctx *sctx, int *pending_move)
  {
  	int ret = 0;
  	struct recorded_ref *cur;
  	struct recorded_ref *cur2;
  	struct list_head check_dirs;
  	struct fs_path *valid_path = NULL;
  	u64 ow_inode = 0;
  	u64 ow_gen;
  	int did_overwrite = 0;
  	int is_orphan = 0;
  	u64 last_dir_ino_rm = 0;
  	bool can_rename = true;
  
  verbose_printk("btrfs: process_recorded_refs %llu\n", sctx->cur_ino);
  
  	/*
  	 * This should never happen as the root dir always has the same ref
  	 * which is always '..'
  	 */
  	BUG_ON(sctx->cur_ino <= BTRFS_FIRST_FREE_OBJECTID);
  	INIT_LIST_HEAD(&check_dirs);
  
  	valid_path = fs_path_alloc();
  	if (!valid_path) {
  		ret = -ENOMEM;
  		goto out;
  	}
  
  	/*
  	 * First, check if the first ref of the current inode was overwritten
  	 * before. If yes, we know that the current inode was already orphanized
  	 * and thus use the orphan name. If not, we can use get_cur_path to
  	 * get the path of the first ref as it would like while receiving at
  	 * this point in time.
  	 * New inodes are always orphan at the beginning, so force to use the
  	 * orphan name in this case.
  	 * The first ref is stored in valid_path and will be updated if it
  	 * gets moved around.
  	 */
  	if (!sctx->cur_inode_new) {
  		ret = did_overwrite_first_ref(sctx, sctx->cur_ino,
  				sctx->cur_inode_gen);
  		if (ret < 0)
  			goto out;
  		if (ret)
  			did_overwrite = 1;
  	}
  	if (sctx->cur_inode_new || did_overwrite) {
  		ret = gen_unique_name(sctx, sctx->cur_ino,
  				sctx->cur_inode_gen, valid_path);
  		if (ret < 0)
  			goto out;
  		is_orphan = 1;
  	} else {
  		ret = get_cur_path(sctx, sctx->cur_ino, sctx->cur_inode_gen,
  				valid_path);
  		if (ret < 0)
  			goto out;
  	}
  
  	list_for_each_entry(cur, &sctx->new_refs, list) {
  		/*
  		 * We may have refs where the parent directory does not exist
  		 * yet. This happens if the parent directories inum is higher
  		 * the the current inum. To handle this case, we create the
  		 * parent directory out of order. But we need to check if this
  		 * did already happen before due to other refs in the same dir.
  		 */
  		ret = get_cur_inode_state(sctx, cur->dir, cur->dir_gen);
  		if (ret < 0)
  			goto out;
  		if (ret == inode_state_will_create) {
  			ret = 0;
  			/*
  			 * First check if any of the current inodes refs did
  			 * already create the dir.
  			 */
  			list_for_each_entry(cur2, &sctx->new_refs, list) {
  				if (cur == cur2)
  					break;
  				if (cur2->dir == cur->dir) {
  					ret = 1;
  					break;
  				}
  			}
  
  			/*
  			 * If that did not happen, check if a previous inode
  			 * did already create the dir.
  			 */
  			if (!ret)
  				ret = did_create_dir(sctx, cur->dir);
  			if (ret < 0)
  				goto out;
  			if (!ret) {
  				ret = send_create_inode(sctx, cur->dir);
  				if (ret < 0)
  					goto out;
  			}
  		}
  
  		/*
  		 * Check if this new ref would overwrite the first ref of
  		 * another unprocessed inode. If yes, orphanize the
  		 * overwritten inode. If we find an overwritten ref that is
  		 * not the first ref, simply unlink it.
  		 */
  		ret = will_overwrite_ref(sctx, cur->dir, cur->dir_gen,
  				cur->name, cur->name_len,
  				&ow_inode, &ow_gen);
  		if (ret < 0)
  			goto out;
  		if (ret) {
  			ret = is_first_ref(sctx->parent_root,
  					   ow_inode, cur->dir, cur->name,
  					   cur->name_len);
  			if (ret < 0)
  				goto out;
  			if (ret) {
  				struct name_cache_entry *nce;
  
  				ret = orphanize_inode(sctx, ow_inode, ow_gen,
  						cur->full_path);
  				if (ret < 0)
  					goto out;
  				/*
  				 * Make sure we clear our orphanized inode's
  				 * name from the name cache. This is because the
  				 * inode ow_inode might be an ancestor of some
  				 * other inode that will be orphanized as well
  				 * later and has an inode number greater than
  				 * sctx->send_progress. We need to prevent
  				 * future name lookups from using the old name
  				 * and get instead the orphan name.
  				 */
  				nce = name_cache_search(sctx, ow_inode, ow_gen);
  				if (nce) {
  					name_cache_delete(sctx, nce);
  					kfree(nce);
  				}
  			} else {
  				ret = send_unlink(sctx, cur->full_path);
  				if (ret < 0)
  					goto out;
  			}
  		}
  
  		if (S_ISDIR(sctx->cur_inode_mode) && sctx->parent_root) {
  			ret = wait_for_dest_dir_move(sctx, cur, is_orphan);
  			if (ret < 0)
  				goto out;
  			if (ret == 1) {
  				can_rename = false;
  				*pending_move = 1;
  			}
  		}
  
  		if (S_ISDIR(sctx->cur_inode_mode) && sctx->parent_root &&
  		    can_rename) {
  			ret = wait_for_parent_move(sctx, cur, is_orphan);
  			if (ret < 0)
  				goto out;
  			if (ret == 1) {
  				can_rename = false;
  				*pending_move = 1;
  			}
  		}
  
  		/*
  		 * link/move the ref to the new place. If we have an orphan
  		 * inode, move it and update valid_path. If not, link or move
  		 * it depending on the inode mode.
  		 */
  		if (is_orphan && can_rename) {
  			ret = send_rename(sctx, valid_path, cur->full_path);
  			if (ret < 0)
  				goto out;
  			is_orphan = 0;
  			ret = fs_path_copy(valid_path, cur->full_path);
  			if (ret < 0)
  				goto out;
  		} else if (can_rename) {
  			if (S_ISDIR(sctx->cur_inode_mode)) {
  				/*
  				 * Dirs can't be linked, so move it. For moved
  				 * dirs, we always have one new and one deleted
  				 * ref. The deleted ref is ignored later.
  				 */
  				ret = send_rename(sctx, valid_path,
  						  cur->full_path);
  				if (!ret)
  					ret = fs_path_copy(valid_path,
  							   cur->full_path);
  				if (ret < 0)
  					goto out;
  			} else {
  				ret = send_link(sctx, cur->full_path,
  						valid_path);
  				if (ret < 0)
  					goto out;
  			}
  		}
  		ret = dup_ref(cur, &check_dirs);
  		if (ret < 0)
  			goto out;
  	}
  
  	if (S_ISDIR(sctx->cur_inode_mode) && sctx->cur_inode_deleted) {
  		/*
  		 * Check if we can already rmdir the directory. If not,
  		 * orphanize it. For every dir item inside that gets deleted
  		 * later, we do this check again and rmdir it then if possible.
  		 * See the use of check_dirs for more details.
  		 */
  		ret = can_rmdir(sctx, sctx->cur_ino, sctx->cur_inode_gen,
  				sctx->cur_ino);
  		if (ret < 0)
  			goto out;
  		if (ret) {
  			ret = send_rmdir(sctx, valid_path);
  			if (ret < 0)
  				goto out;
  		} else if (!is_orphan) {
  			ret = orphanize_inode(sctx, sctx->cur_ino,
  					sctx->cur_inode_gen, valid_path);
  			if (ret < 0)
  				goto out;
  			is_orphan = 1;
  		}
  
  		list_for_each_entry(cur, &sctx->deleted_refs, list) {
  			ret = dup_ref(cur, &check_dirs);
  			if (ret < 0)
  				goto out;
  		}
  	} else if (S_ISDIR(sctx->cur_inode_mode) &&
  		   !list_empty(&sctx->deleted_refs)) {
  		/*
  		 * We have a moved dir. Add the old parent to check_dirs
  		 */
  		cur = list_entry(sctx->deleted_refs.next, struct recorded_ref,
  				list);
  		ret = dup_ref(cur, &check_dirs);
  		if (ret < 0)
  			goto out;
  	} else if (!S_ISDIR(sctx->cur_inode_mode)) {
  		/*
  		 * We have a non dir inode. Go through all deleted refs and
  		 * unlink them if they were not already overwritten by other
  		 * inodes.
  		 */
  		list_for_each_entry(cur, &sctx->deleted_refs, list) {
  			ret = did_overwrite_ref(sctx, cur->dir, cur->dir_gen,
  					sctx->cur_ino, sctx->cur_inode_gen,
  					cur->name, cur->name_len);
  			if (ret < 0)
  				goto out;
  			if (!ret) {
  				ret = send_unlink(sctx, cur->full_path);
  				if (ret < 0)
  					goto out;
  			}
  			ret = dup_ref(cur, &check_dirs);
  			if (ret < 0)
  				goto out;
  		}
  		/*
  		 * If the inode is still orphan, unlink the orphan. This may
  		 * happen when a previous inode did overwrite the first ref
  		 * of this inode and no new refs were added for the current
  		 * inode. Unlinking does not mean that the inode is deleted in
  		 * all cases. There may still be links to this inode in other
  		 * places.
  		 */
  		if (is_orphan) {
  			ret = send_unlink(sctx, valid_path);
  			if (ret < 0)
  				goto out;
  		}
  	}
  
  	/*
  	 * We did collect all parent dirs where cur_inode was once located. We
  	 * now go through all these dirs and check if they are pending for
  	 * deletion and if it's finally possible to perform the rmdir now.
  	 * We also update the inode stats of the parent dirs here.
  	 */
  	list_for_each_entry(cur, &check_dirs, list) {
  		/*
  		 * In case we had refs into dirs that were not processed yet,
  		 * we don't need to do the utime and rmdir logic for these dirs.
  		 * The dir will be processed later.
  		 */
  		if (cur->dir > sctx->cur_ino)
  			continue;
  
  		ret = get_cur_inode_state(sctx, cur->dir, cur->dir_gen);
  		if (ret < 0)
  			goto out;
  
  		if (ret == inode_state_did_create ||
  		    ret == inode_state_no_change) {
  			/* TODO delayed utimes */
  			ret = send_utimes(sctx, cur->dir, cur->dir_gen);
  			if (ret < 0)
  				goto out;
  		} else if (ret == inode_state_did_delete &&
  			   cur->dir != last_dir_ino_rm) {
  			ret = can_rmdir(sctx, cur->dir, cur->dir_gen,
  					sctx->cur_ino);
  			if (ret < 0)
  				goto out;
  			if (ret) {
  				ret = get_cur_path(sctx, cur->dir,
  						   cur->dir_gen, valid_path);
  				if (ret < 0)
  					goto out;
  				ret = send_rmdir(sctx, valid_path);
  				if (ret < 0)
  					goto out;
  				last_dir_ino_rm = cur->dir;
  			}
  		}
  	}
  
  	ret = 0;
  
  out:
  	__free_recorded_refs(&check_dirs);
  	free_recorded_refs(sctx);
  	fs_path_free(valid_path);
  	return ret;
  }
  
  static int record_ref(struct btrfs_root *root, int num, u64 dir, int index,
  		      struct fs_path *name, void *ctx, struct list_head *refs)
  {
  	int ret = 0;
  	struct send_ctx *sctx = ctx;
  	struct fs_path *p;
  	u64 gen;
  
  	p = fs_path_alloc();
  	if (!p)
  		return -ENOMEM;
  
  	ret = get_inode_info(root, dir, NULL, &gen, NULL, NULL,
  			NULL, NULL);
  	if (ret < 0)
  		goto out;
  
  	ret = get_cur_path(sctx, dir, gen, p);
  	if (ret < 0)
  		goto out;
  	ret = fs_path_add_path(p, name);
  	if (ret < 0)
  		goto out;
  
  	ret = __record_ref(refs, dir, gen, p);
  
  out:
  	if (ret)
  		fs_path_free(p);
  	return ret;
  }
  
  static int __record_new_ref(int num, u64 dir, int index,
  			    struct fs_path *name,
  			    void *ctx)
  {
  	struct send_ctx *sctx = ctx;
  	return record_ref(sctx->send_root, num, dir, index, name,
  			  ctx, &sctx->new_refs);
  }
  
  
  static int __record_deleted_ref(int num, u64 dir, int index,
  				struct fs_path *name,
  				void *ctx)
  {
  	struct send_ctx *sctx = ctx;
  	return record_ref(sctx->parent_root, num, dir, index, name,
  			  ctx, &sctx->deleted_refs);
  }
  
  static int record_new_ref(struct send_ctx *sctx)
  {
  	int ret;
  
  	ret = iterate_inode_ref(sctx->send_root, sctx->left_path,
  				sctx->cmp_key, 0, __record_new_ref, sctx);
  	if (ret < 0)
  		goto out;
  	ret = 0;
  
  out:
  	return ret;
  }
  
  static int record_deleted_ref(struct send_ctx *sctx)
  {
  	int ret;
  
  	ret = iterate_inode_ref(sctx->parent_root, sctx->right_path,
  				sctx->cmp_key, 0, __record_deleted_ref, sctx);
  	if (ret < 0)
  		goto out;
  	ret = 0;
  
  out:
  	return ret;
  }
  
  struct find_ref_ctx {
  	u64 dir;
  	u64 dir_gen;
  	struct btrfs_root *root;
  	struct fs_path *name;
  	int found_idx;
  };
  
  static int __find_iref(int num, u64 dir, int index,
  		       struct fs_path *name,
  		       void *ctx_)
  {
  	struct find_ref_ctx *ctx = ctx_;
  	u64 dir_gen;
  	int ret;
  
  	if (dir == ctx->dir && fs_path_len(name) == fs_path_len(ctx->name) &&
  	    strncmp(name->start, ctx->name->start, fs_path_len(name)) == 0) {
  		/*
  		 * To avoid doing extra lookups we'll only do this if everything
  		 * else matches.
  		 */
  		ret = get_inode_info(ctx->root, dir, NULL, &dir_gen, NULL,
  				     NULL, NULL, NULL);
  		if (ret)
  			return ret;
  		if (dir_gen != ctx->dir_gen)
  			return 0;
  		ctx->found_idx = num;
  		return 1;
  	}
  	return 0;
  }
  
  static int find_iref(struct btrfs_root *root,
  		     struct btrfs_path *path,
  		     struct btrfs_key *key,
  		     u64 dir, u64 dir_gen, struct fs_path *name)
  {
  	int ret;
  	struct find_ref_ctx ctx;
  
  	ctx.dir = dir;
  	ctx.name = name;
  	ctx.dir_gen = dir_gen;
  	ctx.found_idx = -1;
  	ctx.root = root;
  
  	ret = iterate_inode_ref(root, path, key, 0, __find_iref, &ctx);
  	if (ret < 0)
  		return ret;
  
  	if (ctx.found_idx == -1)
  		return -ENOENT;
  
  	return ctx.found_idx;
  }
  
  static int __record_changed_new_ref(int num, u64 dir, int index,
  				    struct fs_path *name,
  				    void *ctx)
  {
  	u64 dir_gen;
  	int ret;
  	struct send_ctx *sctx = ctx;
  
  	ret = get_inode_info(sctx->send_root, dir, NULL, &dir_gen, NULL,
  			     NULL, NULL, NULL);
  	if (ret)
  		return ret;
  
  	ret = find_iref(sctx->parent_root, sctx->right_path,
  			sctx->cmp_key, dir, dir_gen, name);
  	if (ret == -ENOENT)
  		ret = __record_new_ref(num, dir, index, name, sctx);
  	else if (ret > 0)
  		ret = 0;
  
  	return ret;
  }
  
  static int __record_changed_deleted_ref(int num, u64 dir, int index,
  					struct fs_path *name,
  					void *ctx)
  {
  	u64 dir_gen;
  	int ret;
  	struct send_ctx *sctx = ctx;
  
  	ret = get_inode_info(sctx->parent_root, dir, NULL, &dir_gen, NULL,
  			     NULL, NULL, NULL);
  	if (ret)
  		return ret;
  
  	ret = find_iref(sctx->send_root, sctx->left_path, sctx->cmp_key,
  			dir, dir_gen, name);
  	if (ret == -ENOENT)
  		ret = __record_deleted_ref(num, dir, index, name, sctx);
  	else if (ret > 0)
  		ret = 0;
  
  	return ret;
  }
  
  static int record_changed_ref(struct send_ctx *sctx)
  {
  	int ret = 0;
  
  	ret = iterate_inode_ref(sctx->send_root, sctx->left_path,
  			sctx->cmp_key, 0, __record_changed_new_ref, sctx);
  	if (ret < 0)
  		goto out;
  	ret = iterate_inode_ref(sctx->parent_root, sctx->right_path,
  			sctx->cmp_key, 0, __record_changed_deleted_ref, sctx);
  	if (ret < 0)
  		goto out;
  	ret = 0;
  
  out:
  	return ret;
  }
  
  /*
   * Record and process all refs at once. Needed when an inode changes the
   * generation number, which means that it was deleted and recreated.
   */
  static int process_all_refs(struct send_ctx *sctx,
  			    enum btrfs_compare_tree_result cmd)
  {
  	int ret;
  	struct btrfs_root *root;
  	struct btrfs_path *path;
  	struct btrfs_key key;
  	struct btrfs_key found_key;
  	struct extent_buffer *eb;
  	int slot;
  	iterate_inode_ref_t cb;
  	int pending_move = 0;
  
  	path = alloc_path_for_send();
  	if (!path)
  		return -ENOMEM;
  
  	if (cmd == BTRFS_COMPARE_TREE_NEW) {
  		root = sctx->send_root;
  		cb = __record_new_ref;
  	} else if (cmd == BTRFS_COMPARE_TREE_DELETED) {
  		root = sctx->parent_root;
  		cb = __record_deleted_ref;
  	} else {
  		btrfs_err(sctx->send_root->fs_info,
  				"Wrong command %d in process_all_refs", cmd);
  		ret = -EINVAL;
  		goto out;
  	}
  
  	key.objectid = sctx->cmp_key->objectid;
  	key.type = BTRFS_INODE_REF_KEY;
  	key.offset = 0;
  	ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
  	if (ret < 0)
  		goto out;
  
  	while (1) {
  		eb = path->nodes[0];
  		slot = path->slots[0];
  		if (slot >= btrfs_header_nritems(eb)) {
  			ret = btrfs_next_leaf(root, path);
  			if (ret < 0)
  				goto out;
  			else if (ret > 0)
  				break;
  			continue;
  		}
  
  		btrfs_item_key_to_cpu(eb, &found_key, slot);
  
  		if (found_key.objectid != key.objectid ||
  		    (found_key.type != BTRFS_INODE_REF_KEY &&
  		     found_key.type != BTRFS_INODE_EXTREF_KEY))
  			break;
  
  		ret = iterate_inode_ref(root, path, &found_key, 0, cb, sctx);
  		if (ret < 0)
  			goto out;
  
  		path->slots[0]++;
  	}
  	btrfs_release_path(path);
  
  	ret = process_recorded_refs(sctx, &pending_move);
  	/* Only applicable to an incremental send. */
  	ASSERT(pending_move == 0);
  
  out:
  	btrfs_free_path(path);
  	return ret;
  }
  
  static int send_set_xattr(struct send_ctx *sctx,
  			  struct fs_path *path,
  			  const char *name, int name_len,
  			  const char *data, int data_len)
  {
  	int ret = 0;
  
  	ret = begin_cmd(sctx, BTRFS_SEND_C_SET_XATTR);
  	if (ret < 0)
  		goto out;
  
  	TLV_PUT_PATH(sctx, BTRFS_SEND_A_PATH, path);
  	TLV_PUT_STRING(sctx, BTRFS_SEND_A_XATTR_NAME, name, name_len);
  	TLV_PUT(sctx, BTRFS_SEND_A_XATTR_DATA, data, data_len);
  
  	ret = send_cmd(sctx);
  
  tlv_put_failure:
  out:
  	return ret;
  }
  
  static int send_remove_xattr(struct send_ctx *sctx,
  			  struct fs_path *path,
  			  const char *name, int name_len)
  {
  	int ret = 0;
  
  	ret = begin_cmd(sctx, BTRFS_SEND_C_REMOVE_XATTR);
  	if (ret < 0)
  		goto out;
  
  	TLV_PUT_PATH(sctx, BTRFS_SEND_A_PATH, path);
  	TLV_PUT_STRING(sctx, BTRFS_SEND_A_XATTR_NAME, name, name_len);
  
  	ret = send_cmd(sctx);
  
  tlv_put_failure:
  out:
  	return ret;
  }
  
  static int __process_new_xattr(int num, struct btrfs_key *di_key,
  			       const char *name, int name_len,
  			       const char *data, int data_len,
  			       u8 type, void *ctx)
  {
  	int ret;
  	struct send_ctx *sctx = ctx;
  	struct fs_path *p;
  	posix_acl_xattr_header dummy_acl;
  
  	p = fs_path_alloc();
  	if (!p)
  		return -ENOMEM;
  
  	/*
  	 * This hack is needed because empty acl's are stored as zero byte
  	 * data in xattrs. Problem with that is, that receiving these zero byte
  	 * acl's will fail later. To fix this, we send a dummy acl list that
  	 * only contains the version number and no entries.
  	 */
  	if (!strncmp(name, XATTR_NAME_POSIX_ACL_ACCESS, name_len) ||
  	    !strncmp(name, XATTR_NAME_POSIX_ACL_DEFAULT, name_len)) {
  		if (data_len == 0) {
  			dummy_acl.a_version =
  					cpu_to_le32(POSIX_ACL_XATTR_VERSION);
  			data = (char *)&dummy_acl;
  			data_len = sizeof(dummy_acl);
  		}
  	}
  
  	ret = get_cur_path(sctx, sctx->cur_ino, sctx->cur_inode_gen, p);
  	if (ret < 0)
  		goto out;
  
  	ret = send_set_xattr(sctx, p, name, name_len, data, data_len);
  
  out:
  	fs_path_free(p);
  	return ret;
  }
  
  static int __process_deleted_xattr(int num, struct btrfs_key *di_key,
  				   const char *name, int name_len,
  				   const char *data, int data_len,
  				   u8 type, void *ctx)
  {
  	int ret;
  	struct send_ctx *sctx = ctx;
  	struct fs_path *p;
  
  	p = fs_path_alloc();
  	if (!p)
  		return -ENOMEM;
  
  	ret = get_cur_path(sctx, sctx->cur_ino, sctx->cur_inode_gen, p);
  	if (ret < 0)
  		goto out;
  
  	ret = send_remove_xattr(sctx, p, name, name_len);
  
  out:
  	fs_path_free(p);
  	return ret;
  }
  
  static int process_new_xattr(struct send_ctx *sctx)
  {
  	int ret = 0;
  
  	ret = iterate_dir_item(sctx->send_root, sctx->left_path,
  			       sctx->cmp_key, __process_new_xattr, sctx);
  
  	return ret;
  }
  
  static int process_deleted_xattr(struct send_ctx *sctx)
  {
  	int ret;
  
  	ret = iterate_dir_item(sctx->parent_root, sctx->right_path,
  			       sctx->cmp_key, __process_deleted_xattr, sctx);
  
  	return ret;
  }
  
  struct find_xattr_ctx {
  	const char *name;
  	int name_len;
  	int found_idx;
  	char *found_data;
  	int found_data_len;
  };
  
  static int __find_xattr(int num, struct btrfs_key *di_key,
  			const char *name, int name_len,
  			const char *data, int data_len,
  			u8 type, void *vctx)
  {
  	struct find_xattr_ctx *ctx = vctx;
  
  	if (name_len == ctx->name_len &&
  	    strncmp(name, ctx->name, name_len) == 0) {
  		ctx->found_idx = num;
  		ctx->found_data_len = data_len;
  		ctx->found_data = kmemdup(data, data_len, GFP_NOFS);
  		if (!ctx->found_data)
  			return -ENOMEM;
  		return 1;
  	}
  	return 0;
  }
  
  static int find_xattr(struct btrfs_root *root,
  		      struct btrfs_path *path,
  		      struct btrfs_key *key,
  		      const char *name, int name_len,
  		      char **data, int *data_len)
  {
  	int ret;
  	struct find_xattr_ctx ctx;
  
  	ctx.name = name;
  	ctx.name_len = name_len;
  	ctx.found_idx = -1;
  	ctx.found_data = NULL;
  	ctx.found_data_len = 0;
  
  	ret = iterate_dir_item(root, path, key, __find_xattr, &ctx);
  	if (ret < 0)
  		return ret;
  
  	if (ctx.found_idx == -1)
  		return -ENOENT;
  	if (data) {
  		*data = ctx.found_data;
  		*data_len = ctx.found_data_len;
  	} else {
  		kfree(ctx.found_data);
  	}
  	return ctx.found_idx;
  }
  
  
  static int __process_changed_new_xattr(int num, struct btrfs_key *di_key,
  				       const char *name, int name_len,
  				       const char *data, int data_len,
  				       u8 type, void *ctx)
  {
  	int ret;
  	struct send_ctx *sctx = ctx;
  	char *found_data = NULL;
  	int found_data_len  = 0;
  
  	ret = find_xattr(sctx->parent_root, sctx->right_path,
  			 sctx->cmp_key, name, name_len, &found_data,
  			 &found_data_len);
  	if (ret == -ENOENT) {
  		ret = __process_new_xattr(num, di_key, name, name_len, data,
  				data_len, type, ctx);
  	} else if (ret >= 0) {
  		if (data_len != found_data_len ||
  		    memcmp(data, found_data, data_len)) {
  			ret = __process_new_xattr(num, di_key, name, name_len,
  					data, data_len, type, ctx);
  		} else {
  			ret = 0;
  		}
  	}
  
  	kfree(found_data);
  	return ret;
  }
  
  static int __process_changed_deleted_xattr(int num, struct btrfs_key *di_key,
  					   const char *name, int name_len,
  					   const char *data, int data_len,
  					   u8 type, void *ctx)
  {
  	int ret;
  	struct send_ctx *sctx = ctx;
  
  	ret = find_xattr(sctx->send_root, sctx->left_path, sctx->cmp_key,
  			 name, name_len, NULL, NULL);
  	if (ret == -ENOENT)
  		ret = __process_deleted_xattr(num, di_key, name, name_len, data,
  				data_len, type, ctx);
  	else if (ret >= 0)
  		ret = 0;
  
  	return ret;
  }
  
  static int process_changed_xattr(struct send_ctx *sctx)
  {
  	int ret = 0;
  
  	ret = iterate_dir_item(sctx->send_root, sctx->left_path,
  			sctx->cmp_key, __process_changed_new_xattr, sctx);
  	if (ret < 0)
  		goto out;
  	ret = iterate_dir_item(sctx->parent_root, sctx->right_path,
  			sctx->cmp_key, __process_changed_deleted_xattr, sctx);
  
  out:
  	return ret;
  }
  
  static int process_all_new_xattrs(struct send_ctx *sctx)
  {
  	int ret;
  	struct btrfs_root *root;
  	struct btrfs_path *path;
  	struct btrfs_key key;
  	struct btrfs_key found_key;
  	struct extent_buffer *eb;
  	int slot;
  
  	path = alloc_path_for_send();
  	if (!path)
  		return -ENOMEM;
  
  	root = sctx->send_root;
  
  	key.objectid = sctx->cmp_key->objectid;
  	key.type = BTRFS_XATTR_ITEM_KEY;
  	key.offset = 0;
  	ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
  	if (ret < 0)
  		goto out;
  
  	while (1) {
  		eb = path->nodes[0];
  		slot = path->slots[0];
  		if (slot >= btrfs_header_nritems(eb)) {
  			ret = btrfs_next_leaf(root, path);
  			if (ret < 0) {
  				goto out;
  			} else if (ret > 0) {
  				ret = 0;
  				break;
  			}
  			continue;
  		}
  
  		btrfs_item_key_to_cpu(eb, &found_key, slot);
  		if (found_key.objectid != key.objectid ||
  		    found_key.type != key.type) {
  			ret = 0;
  			goto out;
  		}
  
  		ret = iterate_dir_item(root, path, &found_key,
  				       __process_new_xattr, sctx);
  		if (ret < 0)
  			goto out;
  
  		path->slots[0]++;
  	}
  
  out:
  	btrfs_free_path(path);
  	return ret;
  }
  
  static ssize_t fill_read_buf(struct send_ctx *sctx, u64 offset, u32 len)
  {
  	struct btrfs_root *root = sctx->send_root;
  	struct btrfs_fs_info *fs_info = root->fs_info;
  	struct inode *inode;
  	struct page *page;
  	char *addr;
  	struct btrfs_key key;
  	pgoff_t index = offset >> PAGE_CACHE_SHIFT;
  	pgoff_t last_index;
  	unsigned pg_offset = offset & ~PAGE_CACHE_MASK;
  	ssize_t ret = 0;
  
  	key.objectid = sctx->cur_ino;
  	key.type = BTRFS_INODE_ITEM_KEY;
  	key.offset = 0;
  
  	inode = btrfs_iget(fs_info->sb, &key, root, NULL);
  	if (IS_ERR(inode))
  		return PTR_ERR(inode);
  
  	if (offset + len > i_size_read(inode)) {
  		if (offset > i_size_read(inode))
  			len = 0;
  		else
  			len = offset - i_size_read(inode);
  	}
  	if (len == 0)
  		goto out;
  
  	last_index = (offset + len - 1) >> PAGE_CACHE_SHIFT;
  
  	/* initial readahead */
  	memset(&sctx->ra, 0, sizeof(struct file_ra_state));
  	file_ra_state_init(&sctx->ra, inode->i_mapping);
  	btrfs_force_ra(inode->i_mapping, &sctx->ra, NULL, index,
  		       last_index - index + 1);
  
  	while (index <= last_index) {
  		unsigned cur_len = min_t(unsigned, len,
  					 PAGE_CACHE_SIZE - pg_offset);
  		page = find_or_create_page(inode->i_mapping, index, GFP_NOFS);
  		if (!page) {
  			ret = -ENOMEM;
  			break;
  		}
  
  		if (!PageUptodate(page)) {
  			btrfs_readpage(NULL, page);
  			lock_page(page);
  			if (!PageUptodate(page)) {
  				unlock_page(page);
  				page_cache_release(page);
  				ret = -EIO;
  				break;
  			}
  		}
  
  		addr = kmap(page);
  		memcpy(sctx->read_buf + ret, addr + pg_offset, cur_len);
  		kunmap(page);
  		unlock_page(page);
  		page_cache_release(page);
  		index++;
  		pg_offset = 0;
  		len -= cur_len;
  		ret += cur_len;
  	}
  out:
  	iput(inode);
  	return ret;
  }
  
  /*
   * Read some bytes from the current inode/file and send a write command to
   * user space.
   */
  static int send_write(struct send_ctx *sctx, u64 offset, u32 len)
  {
  	int ret = 0;
  	struct fs_path *p;
  	ssize_t num_read = 0;
  
  	p = fs_path_alloc();
  	if (!p)
  		return -ENOMEM;
  
  verbose_printk("btrfs: send_write offset=%llu, len=%d\n", offset, len);
  
  	num_read = fill_read_buf(sctx, offset, len);
  	if (num_read <= 0) {
  		if (num_read < 0)
  			ret = num_read;
  		goto out;
  	}
  
  	ret = begin_cmd(sctx, BTRFS_SEND_C_WRITE);
  	if (ret < 0)
  		goto out;
  
  	ret = get_cur_path(sctx, sctx->cur_ino, sctx->cur_inode_gen, p);
  	if (ret < 0)
  		goto out;
  
  	TLV_PUT_PATH(sctx, BTRFS_SEND_A_PATH, p);
  	TLV_PUT_U64(sctx, BTRFS_SEND_A_FILE_OFFSET, offset);
  	TLV_PUT(sctx, BTRFS_SEND_A_DATA, sctx->read_buf, num_read);
  
  	ret = send_cmd(sctx);
  
  tlv_put_failure:
  out:
  	fs_path_free(p);
  	if (ret < 0)
  		return ret;
  	return num_read;
  }
  
  /*
   * Send a clone command to user space.
   */
  static int send_clone(struct send_ctx *sctx,
  		      u64 offset, u32 len,
  		      struct clone_root *clone_root)
  {
  	int ret = 0;
  	struct fs_path *p;
  	u64 gen;
  
  verbose_printk("btrfs: send_clone offset=%llu, len=%d, clone_root=%llu, "
  	       "clone_inode=%llu, clone_offset=%llu\n", offset, len,
  		clone_root->root->objectid, clone_root->ino,
  		clone_root->offset);
  
  	p = fs_path_alloc();
  	if (!p)
  		return -ENOMEM;
  
  	ret = begin_cmd(sctx, BTRFS_SEND_C_CLONE);
  	if (ret < 0)
  		goto out;
  
  	ret = get_cur_path(sctx, sctx->cur_ino, sctx->cur_inode_gen, p);
  	if (ret < 0)
  		goto out;
  
  	TLV_PUT_U64(sctx, BTRFS_SEND_A_FILE_OFFSET, offset);
  	TLV_PUT_U64(sctx, BTRFS_SEND_A_CLONE_LEN, len);
  	TLV_PUT_PATH(sctx, BTRFS_SEND_A_PATH, p);
  
  	if (clone_root->root == sctx->send_root) {
  		ret = get_inode_info(sctx->send_root, clone_root->ino, NULL,
  				&gen, NULL, NULL, NULL, NULL);
  		if (ret < 0)
  			goto out;
  		ret = get_cur_path(sctx, clone_root->ino, gen, p);
  	} else {
  		ret = get_inode_path(clone_root->root, clone_root->ino, p);
  	}
  	if (ret < 0)
  		goto out;
  
  	/*
  	 * If the parent we're using has a received_uuid set then use that as
  	 * our clone source as that is what we will look for when doing a
  	 * receive.
  	 *
  	 * This covers the case that we create a snapshot off of a received
  	 * subvolume and then use that as the parent and try to receive on a
  	 * different host.
  	 */
  	if (!btrfs_is_empty_uuid(clone_root->root->root_item.received_uuid))
  		TLV_PUT_UUID(sctx, BTRFS_SEND_A_CLONE_UUID,
  			     clone_root->root->root_item.received_uuid);
  	else
  		TLV_PUT_UUID(sctx, BTRFS_SEND_A_CLONE_UUID,
  			     clone_root->root->root_item.uuid);
  	TLV_PUT_U64(sctx, BTRFS_SEND_A_CLONE_CTRANSID,
  		    le64_to_cpu(clone_root->root->root_item.ctransid));
  	TLV_PUT_PATH(sctx, BTRFS_SEND_A_CLONE_PATH, p);
  	TLV_PUT_U64(sctx, BTRFS_SEND_A_CLONE_OFFSET,
  			clone_root->offset);
  
  	ret = send_cmd(sctx);
  
  tlv_put_failure:
  out:
  	fs_path_free(p);
  	return ret;
  }
  
  /*
   * Send an update extent command to user space.
   */
  static int send_update_extent(struct send_ctx *sctx,
  			      u64 offset, u32 len)
  {
  	int ret = 0;
  	struct fs_path *p;
  
  	p = fs_path_alloc();
  	if (!p)
  		return -ENOMEM;
  
  	ret = begin_cmd(sctx, BTRFS_SEND_C_UPDATE_EXTENT);
  	if (ret < 0)
  		goto out;
  
  	ret = get_cur_path(sctx, sctx->cur_ino, sctx->cur_inode_gen, p);
  	if (ret < 0)
  		goto out;
  
  	TLV_PUT_PATH(sctx, BTRFS_SEND_A_PATH, p);
  	TLV_PUT_U64(sctx, BTRFS_SEND_A_FILE_OFFSET, offset);
  	TLV_PUT_U64(sctx, BTRFS_SEND_A_SIZE, len);
  
  	ret = send_cmd(sctx);
  
  tlv_put_failure:
  out:
  	fs_path_free(p);
  	return ret;
  }
  
  static int send_hole(struct send_ctx *sctx, u64 end)
  {
  	struct fs_path *p = NULL;
  	u64 offset = sctx->cur_inode_last_extent;
  	u64 len;
  	int ret = 0;
  
  	p = fs_path_alloc();
  	if (!p)
  		return -ENOMEM;
  	ret = get_cur_path(sctx, sctx->cur_ino, sctx->cur_inode_gen, p);
  	if (ret < 0)
  		goto tlv_put_failure;
  	memset(sctx->read_buf, 0, BTRFS_SEND_READ_SIZE);
  	while (offset < end) {
  		len = min_t(u64, end - offset, BTRFS_SEND_READ_SIZE);
  
  		ret = begin_cmd(sctx, BTRFS_SEND_C_WRITE);
  		if (ret < 0)
  			break;
  		TLV_PUT_PATH(sctx, BTRFS_SEND_A_PATH, p);
  		TLV_PUT_U64(sctx, BTRFS_SEND_A_FILE_OFFSET, offset);
  		TLV_PUT(sctx, BTRFS_SEND_A_DATA, sctx->read_buf, len);
  		ret = send_cmd(sctx);
  		if (ret < 0)
  			break;
  		offset += len;
  	}
  tlv_put_failure:
  	fs_path_free(p);
  	return ret;
  }
  
  static int send_extent_data(struct send_ctx *sctx,
  			    const u64 offset,
  			    const u64 len)
  {
  	u64 sent = 0;
  
  	if (sctx->flags & BTRFS_SEND_FLAG_NO_FILE_DATA)
  		return send_update_extent(sctx, offset, len);
  
  	while (sent < len) {
  		u64 size = len - sent;
  		int ret;
  
  		if (size > BTRFS_SEND_READ_SIZE)
  			size = BTRFS_SEND_READ_SIZE;
  		ret = send_write(sctx, offset + sent, size);
  		if (ret < 0)
  			return ret;
  		if (!ret)
  			break;
  		sent += ret;
  	}
  	return 0;
  }
  
  static int clone_range(struct send_ctx *sctx,
  		       struct clone_root *clone_root,
  		       const u64 disk_byte,
  		       u64 data_offset,
  		       u64 offset,
  		       u64 len)
  {
  	struct btrfs_path *path;
  	struct btrfs_key key;
  	int ret;
  
  	path = alloc_path_for_send();
  	if (!path)
  		return -ENOMEM;
  
  	/*
  	 * We can't send a clone operation for the entire range if we find
  	 * extent items in the respective range in the source file that
  	 * refer to different extents or if we find holes.
  	 * So check for that and do a mix of clone and regular write/copy
  	 * operations if needed.
  	 *
  	 * Example:
  	 *
  	 * mkfs.btrfs -f /dev/sda
  	 * mount /dev/sda /mnt
  	 * xfs_io -f -c "pwrite -S 0xaa 0K 100K" /mnt/foo
  	 * cp --reflink=always /mnt/foo /mnt/bar
  	 * xfs_io -c "pwrite -S 0xbb 50K 50K" /mnt/foo
  	 * btrfs subvolume snapshot -r /mnt /mnt/snap
  	 *
  	 * If when we send the snapshot and we are processing file bar (which
  	 * has a higher inode number than foo) we blindly send a clone operation
  	 * for the [0, 100K[ range from foo to bar, the receiver ends up getting
  	 * a file bar that matches the content of file foo - iow, doesn't match
  	 * the content from bar in the original filesystem.
  	 */
  	key.objectid = clone_root->ino;
  	key.type = BTRFS_EXTENT_DATA_KEY;
  	key.offset = clone_root->offset;
  	ret = btrfs_search_slot(NULL, clone_root->root, &key, path, 0, 0);
  	if (ret < 0)
  		goto out;
  	if (ret > 0 && path->slots[0] > 0) {
  		btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0] - 1);
  		if (key.objectid == clone_root->ino &&
  		    key.type == BTRFS_EXTENT_DATA_KEY)
  			path->slots[0]--;
  	}
  
  	while (true) {
  		struct extent_buffer *leaf = path->nodes[0];
  		int slot = path->slots[0];
  		struct btrfs_file_extent_item *ei;
  		u8 type;
  		u64 ext_len;
  		u64 clone_len;
  
  		if (slot >= btrfs_header_nritems(leaf)) {
  			ret = btrfs_next_leaf(clone_root->root, path);
  			if (ret < 0)
  				goto out;
  			else if (ret > 0)
  				break;
  			continue;
  		}
  
  		btrfs_item_key_to_cpu(leaf, &key, slot);
  
  		/*
  		 * We might have an implicit trailing hole (NO_HOLES feature
  		 * enabled). We deal with it after leaving this loop.
  		 */
  		if (key.objectid != clone_root->ino ||
  		    key.type != BTRFS_EXTENT_DATA_KEY)
  			break;
  
  		ei = btrfs_item_ptr(leaf, slot, struct btrfs_file_extent_item);
  		type = btrfs_file_extent_type(leaf, ei);
  		if (type == BTRFS_FILE_EXTENT_INLINE) {
  			ext_len = btrfs_file_extent_inline_len(leaf, slot, ei);
  			ext_len = PAGE_CACHE_ALIGN(ext_len);
  		} else {
  			ext_len = btrfs_file_extent_num_bytes(leaf, ei);
  		}
  
  		if (key.offset + ext_len <= clone_root->offset)
  			goto next;
  
  		if (key.offset > clone_root->offset) {
  			/* Implicit hole, NO_HOLES feature enabled. */
  			u64 hole_len = key.offset - clone_root->offset;
  
  			if (hole_len > len)
  				hole_len = len;
  			ret = send_extent_data(sctx, offset, hole_len);
  			if (ret < 0)
  				goto out;
  
  			len -= hole_len;
  			if (len == 0)
  				break;
  			offset += hole_len;
  			clone_root->offset += hole_len;
  			data_offset += hole_len;
  		}
  
  		if (key.offset >= clone_root->offset + len)
  			break;
  
  		clone_len = min_t(u64, ext_len, len);
  
  		if (btrfs_file_extent_disk_bytenr(leaf, ei) == disk_byte &&
  		    btrfs_file_extent_offset(leaf, ei) == data_offset)
  			ret = send_clone(sctx, offset, clone_len, clone_root);
  		else
  			ret = send_extent_data(sctx, offset, clone_len);
  
  		if (ret < 0)
  			goto out;
  
  		len -= clone_len;
  		if (len == 0)
  			break;
  		offset += clone_len;
  		clone_root->offset += clone_len;
  		data_offset += clone_len;
  next:
  		path->slots[0]++;
  	}
  
  	if (len > 0)
  		ret = send_extent_data(sctx, offset, len);
  	else
  		ret = 0;
  out:
  	btrfs_free_path(path);
  	return ret;
  }
  
  static int send_write_or_clone(struct send_ctx *sctx,
  			       struct btrfs_path *path,
  			       struct btrfs_key *key,
  			       struct clone_root *clone_root)
  {
  	int ret = 0;
  	struct btrfs_file_extent_item *ei;
  	u64 offset = key->offset;
  	u64 len;
  	u8 type;
  	u64 bs = sctx->send_root->fs_info->sb->s_blocksize;
  
  	ei = btrfs_item_ptr(path->nodes[0], path->slots[0],
  			struct btrfs_file_extent_item);
  	type = btrfs_file_extent_type(path->nodes[0], ei);
  	if (type == BTRFS_FILE_EXTENT_INLINE) {
  		len = btrfs_file_extent_inline_len(path->nodes[0],
  						   path->slots[0], ei);
  		/*
  		 * it is possible the inline item won't cover the whole page,
  		 * but there may be items after this page.  Make
  		 * sure to send the whole thing
  		 */
  		len = PAGE_CACHE_ALIGN(len);
  	} else {
  		len = btrfs_file_extent_num_bytes(path->nodes[0], ei);
  	}
  
  	if (offset + len > sctx->cur_inode_size)
  		len = sctx->cur_inode_size - offset;
  	if (len == 0) {
  		ret = 0;
  		goto out;
  	}
  
  	if (clone_root && IS_ALIGNED(offset + len, bs)) {
  		u64 disk_byte;
  		u64 data_offset;
  
  		disk_byte = btrfs_file_extent_disk_bytenr(path->nodes[0], ei);
  		data_offset = btrfs_file_extent_offset(path->nodes[0], ei);
  		ret = clone_range(sctx, clone_root, disk_byte, data_offset,
  				  offset, len);
  	} else {
  		ret = send_extent_data(sctx, offset, len);
  	}
  out:
  	return ret;
  }
  
  static int is_extent_unchanged(struct send_ctx *sctx,
  			       struct btrfs_path *left_path,
  			       struct btrfs_key *ekey)
  {
  	int ret = 0;
  	struct btrfs_key key;
  	struct btrfs_path *path = NULL;
  	struct extent_buffer *eb;
  	int slot;
  	struct btrfs_key found_key;
  	struct btrfs_file_extent_item *ei;
  	u64 left_disknr;
  	u64 right_disknr;
  	u64 left_offset;
  	u64 right_offset;
  	u64 left_offset_fixed;
  	u64 left_len;
  	u64 right_len;
  	u64 left_gen;
  	u64 right_gen;
  	u8 left_type;
  	u8 right_type;
  
  	path = alloc_path_for_send();
  	if (!path)
  		return -ENOMEM;
  
  	eb = left_path->nodes[0];
  	slot = left_path->slots[0];
  	ei = btrfs_item_ptr(eb, slot, struct btrfs_file_extent_item);
  	left_type = btrfs_file_extent_type(eb, ei);
  
  	if (left_type != BTRFS_FILE_EXTENT_REG) {
  		ret = 0;
  		goto out;
  	}
  	left_disknr = btrfs_file_extent_disk_bytenr(eb, ei);
  	left_len = btrfs_file_extent_num_bytes(eb, ei);
  	left_offset = btrfs_file_extent_offset(eb, ei);
  	left_gen = btrfs_file_extent_generation(eb, ei);
  
  	/*
  	 * Following comments will refer to these graphics. L is the left
  	 * extents which we are checking at the moment. 1-8 are the right
  	 * extents that we iterate.
  	 *
  	 *       |-----L-----|
  	 * |-1-|-2a-|-3-|-4-|-5-|-6-|
  	 *
  	 *       |-----L-----|
  	 * |--1--|-2b-|...(same as above)
  	 *
  	 * Alternative situation. Happens on files where extents got split.
  	 *       |-----L-----|
  	 * |-----------7-----------|-6-|
  	 *
  	 * Alternative situation. Happens on files which got larger.
  	 *       |-----L-----|
  	 * |-8-|
  	 * Nothing follows after 8.
  	 */
  
  	key.objectid = ekey->objectid;
  	key.type = BTRFS_EXTENT_DATA_KEY;
  	key.offset = ekey->offset;
  	ret = btrfs_search_slot_for_read(sctx->parent_root, &key, path, 0, 0);
  	if (ret < 0)
  		goto out;
  	if (ret) {
  		ret = 0;
  		goto out;
  	}
  
  	/*
  	 * Handle special case where the right side has no extents at all.
  	 */
  	eb = path->nodes[0];
  	slot = path->slots[0];
  	btrfs_item_key_to_cpu(eb, &found_key, slot);
  	if (found_key.objectid != key.objectid ||
  	    found_key.type != key.type) {
  		/* If we're a hole then just pretend nothing changed */
  		ret = (left_disknr) ? 0 : 1;
  		goto out;
  	}
  
  	/*
  	 * We're now on 2a, 2b or 7.
  	 */
  	key = found_key;
  	while (key.offset < ekey->offset + left_len) {
  		ei = btrfs_item_ptr(eb, slot, struct btrfs_file_extent_item);
  		right_type = btrfs_file_extent_type(eb, ei);
  		if (right_type != BTRFS_FILE_EXTENT_REG) {
  			ret = 0;
  			goto out;
  		}
  
  		right_disknr = btrfs_file_extent_disk_bytenr(eb, ei);
  		right_len = btrfs_file_extent_num_bytes(eb, ei);
  		right_offset = btrfs_file_extent_offset(eb, ei);
  		right_gen = btrfs_file_extent_generation(eb, ei);
  
  		/*
  		 * Are we at extent 8? If yes, we know the extent is changed.
  		 * This may only happen on the first iteration.
  		 */
  		if (found_key.offset + right_len <= ekey->offset) {
  			/* If we're a hole just pretend nothing changed */
  			ret = (left_disknr) ? 0 : 1;
  			goto out;
  		}
  
  		left_offset_fixed = left_offset;
  		if (key.offset < ekey->offset) {
  			/* Fix the right offset for 2a and 7. */
  			right_offset += ekey->offset - key.offset;
  		} else {
  			/* Fix the left offset for all behind 2a and 2b */
  			left_offset_fixed += key.offset - ekey->offset;
  		}
  
  		/*
  		 * Check if we have the same extent.
  		 */
  		if (left_disknr != right_disknr ||
  		    left_offset_fixed != right_offset ||
  		    left_gen != right_gen) {
  			ret = 0;
  			goto out;
  		}
  
  		/*
  		 * Go to the next extent.
  		 */
  		ret = btrfs_next_item(sctx->parent_root, path);
  		if (ret < 0)
  			goto out;
  		if (!ret) {
  			eb = path->nodes[0];
  			slot = path->slots[0];
  			btrfs_item_key_to_cpu(eb, &found_key, slot);
  		}
  		if (ret || found_key.objectid != key.objectid ||
  		    found_key.type != key.type) {
  			key.offset += right_len;
  			break;
  		}
  		if (found_key.offset != key.offset + right_len) {
  			ret = 0;
  			goto out;
  		}
  		key = found_key;
  	}
  
  	/*
  	 * We're now behind the left extent (treat as unchanged) or at the end
  	 * of the right side (treat as changed).
  	 */
  	if (key.offset >= ekey->offset + left_len)
  		ret = 1;
  	else
  		ret = 0;
  
  
  out:
  	btrfs_free_path(path);
  	return ret;
  }
  
  static int get_last_extent(struct send_ctx *sctx, u64 offset)
  {
  	struct btrfs_path *path;
  	struct btrfs_root *root = sctx->send_root;
  	struct btrfs_file_extent_item *fi;
  	struct btrfs_key key;
  	u64 extent_end;
  	u8 type;
  	int ret;
  
  	path = alloc_path_for_send();
  	if (!path)
  		return -ENOMEM;
  
  	sctx->cur_inode_last_extent = 0;
  
  	key.objectid = sctx->cur_ino;
  	key.type = BTRFS_EXTENT_DATA_KEY;
  	key.offset = offset;
  	ret = btrfs_search_slot_for_read(root, &key, path, 0, 1);
  	if (ret < 0)
  		goto out;
  	ret = 0;
  	btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
  	if (key.objectid != sctx->cur_ino || key.type != BTRFS_EXTENT_DATA_KEY)
  		goto out;
  
  	fi = btrfs_item_ptr(path->nodes[0], path->slots[0],
  			    struct btrfs_file_extent_item);
  	type = btrfs_file_extent_type(path->nodes[0], fi);
  	if (type == BTRFS_FILE_EXTENT_INLINE) {
  		u64 size = btrfs_file_extent_inline_len(path->nodes[0],
  							path->slots[0], fi);
  		extent_end = ALIGN(key.offset + size,
  				   sctx->send_root->sectorsize);
  	} else {
  		extent_end = key.offset +
  			btrfs_file_extent_num_bytes(path->nodes[0], fi);
  	}
  	sctx->cur_inode_last_extent = extent_end;
  out:
  	btrfs_free_path(path);
  	return ret;
  }
  
  static int maybe_send_hole(struct send_ctx *sctx, struct btrfs_path *path,
  			   struct btrfs_key *key)
  {
  	struct btrfs_file_extent_item *fi;
  	u64 extent_end;
  	u8 type;
  	int ret = 0;
  
  	if (sctx->cur_ino != key->objectid || !need_send_hole(sctx))
  		return 0;
  
  	if (sctx->cur_inode_last_extent == (u64)-1) {
  		ret = get_last_extent(sctx, key->offset - 1);
  		if (ret)
  			return ret;
  	}
  
  	fi = btrfs_item_ptr(path->nodes[0], path->slots[0],
  			    struct btrfs_file_extent_item);
  	type = btrfs_file_extent_type(path->nodes[0], fi);
  	if (type == BTRFS_FILE_EXTENT_INLINE) {
  		u64 size = btrfs_file_extent_inline_len(path->nodes[0],
  							path->slots[0], fi);
  		extent_end = ALIGN(key->offset + size,
  				   sctx->send_root->sectorsize);
  	} else {
  		extent_end = key->offset +
  			btrfs_file_extent_num_bytes(path->nodes[0], fi);
  	}
  
  	if (path->slots[0] == 0 &&
  	    sctx->cur_inode_last_extent < key->offset) {
  		/*
  		 * We might have skipped entire leafs that contained only
  		 * file extent items for our current inode. These leafs have
  		 * a generation number smaller (older) than the one in the
  		 * current leaf and the leaf our last extent came from, and
  		 * are located between these 2 leafs.
  		 */
  		ret = get_last_extent(sctx, key->offset - 1);
  		if (ret)
  			return ret;
  	}
  
  	if (sctx->cur_inode_last_extent < key->offset)
  		ret = send_hole(sctx, key->offset);
  	sctx->cur_inode_last_extent = extent_end;
  	return ret;
  }
  
  static int process_extent(struct send_ctx *sctx,
  			  struct btrfs_path *path,
  			  struct btrfs_key *key)
  {
  	struct clone_root *found_clone = NULL;
  	int ret = 0;
  
  	if (S_ISLNK(sctx->cur_inode_mode))
  		return 0;
  
  	if (sctx->parent_root && !sctx->cur_inode_new) {
  		ret = is_extent_unchanged(sctx, path, key);
  		if (ret < 0)
  			goto out;
  		if (ret) {
  			ret = 0;
  			goto out_hole;
  		}
  	} else {
  		struct btrfs_file_extent_item *ei;
  		u8 type;
  
  		ei = btrfs_item_ptr(path->nodes[0], path->slots[0],
  				    struct btrfs_file_extent_item);
  		type = btrfs_file_extent_type(path->nodes[0], ei);
  		if (type == BTRFS_FILE_EXTENT_PREALLOC ||
  		    type == BTRFS_FILE_EXTENT_REG) {
  			/*
  			 * The send spec does not have a prealloc command yet,
  			 * so just leave a hole for prealloc'ed extents until
  			 * we have enough commands queued up to justify rev'ing
  			 * the send spec.
  			 */
  			if (type == BTRFS_FILE_EXTENT_PREALLOC) {
  				ret = 0;
  				goto out;
  			}
  
  			/* Have a hole, just skip it. */
  			if (btrfs_file_extent_disk_bytenr(path->nodes[0], ei) == 0) {
  				ret = 0;
  				goto out;
  			}
  		}
  	}
  
  	ret = find_extent_clone(sctx, path, key->objectid, key->offset,
  			sctx->cur_inode_size, &found_clone);
  	if (ret != -ENOENT && ret < 0)
  		goto out;
  
  	ret = send_write_or_clone(sctx, path, key, found_clone);
  	if (ret)
  		goto out;
  out_hole:
  	ret = maybe_send_hole(sctx, path, key);
  out:
  	return ret;
  }
  
  static int process_all_extents(struct send_ctx *sctx)
  {
  	int ret;
  	struct btrfs_root *root;
  	struct btrfs_path *path;
  	struct btrfs_key key;
  	struct btrfs_key found_key;
  	struct extent_buffer *eb;
  	int slot;
  
  	root = sctx->send_root;
  	path = alloc_path_for_send();
  	if (!path)
  		return -ENOMEM;
  
  	key.objectid = sctx->cmp_key->objectid;
  	key.type = BTRFS_EXTENT_DATA_KEY;
  	key.offset = 0;
  	ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
  	if (ret < 0)
  		goto out;
  
  	while (1) {
  		eb = path->nodes[0];
  		slot = path->slots[0];
  
  		if (slot >= btrfs_header_nritems(eb)) {
  			ret = btrfs_next_leaf(root, path);
  			if (ret < 0) {
  				goto out;
  			} else if (ret > 0) {
  				ret = 0;
  				break;
  			}
  			continue;
  		}
  
  		btrfs_item_key_to_cpu(eb, &found_key, slot);
  
  		if (found_key.objectid != key.objectid ||
  		    found_key.type != key.type) {
  			ret = 0;
  			goto out;
  		}
  
  		ret = process_extent(sctx, path, &found_key);
  		if (ret < 0)
  			goto out;
  
  		path->slots[0]++;
  	}
  
  out:
  	btrfs_free_path(path);
  	return ret;
  }
  
  static int process_recorded_refs_if_needed(struct send_ctx *sctx, int at_end,
  					   int *pending_move,
  					   int *refs_processed)
  {
  	int ret = 0;
  
  	if (sctx->cur_ino == 0)
  		goto out;
  	if (!at_end && sctx->cur_ino == sctx->cmp_key->objectid &&
  	    sctx->cmp_key->type <= BTRFS_INODE_EXTREF_KEY)
  		goto out;
  	if (list_empty(&sctx->new_refs) && list_empty(&sctx->deleted_refs))
  		goto out;
  
  	ret = process_recorded_refs(sctx, pending_move);
  	if (ret < 0)
  		goto out;
  
  	*refs_processed = 1;
  out:
  	return ret;
  }
  
  static int finish_inode_if_needed(struct send_ctx *sctx, int at_end)
  {
  	int ret = 0;
  	u64 left_mode;
  	u64 left_uid;
  	u64 left_gid;
  	u64 right_mode;
  	u64 right_uid;
  	u64 right_gid;
  	int need_chmod = 0;
  	int need_chown = 0;
  	int pending_move = 0;
  	int refs_processed = 0;
  
  	ret = process_recorded_refs_if_needed(sctx, at_end, &pending_move,
  					      &refs_processed);
  	if (ret < 0)
  		goto out;
  
  	/*
  	 * We have processed the refs and thus need to advance send_progress.
  	 * Now, calls to get_cur_xxx will take the updated refs of the current
  	 * inode into account.
  	 *
  	 * On the other hand, if our current inode is a directory and couldn't
  	 * be moved/renamed because its parent was renamed/moved too and it has
  	 * a higher inode number, we can only move/rename our current inode
  	 * after we moved/renamed its parent. Therefore in this case operate on
  	 * the old path (pre move/rename) of our current inode, and the
  	 * move/rename will be performed later.
  	 */
  	if (refs_processed && !pending_move)
  		sctx->send_progress = sctx->cur_ino + 1;
  
  	if (sctx->cur_ino == 0 || sctx->cur_inode_deleted)
  		goto out;
  	if (!at_end && sctx->cmp_key->objectid == sctx->cur_ino)
  		goto out;
  
  	ret = get_inode_info(sctx->send_root, sctx->cur_ino, NULL, NULL,
  			&left_mode, &left_uid, &left_gid, NULL);
  	if (ret < 0)
  		goto out;
  
  	if (!sctx->parent_root || sctx->cur_inode_new) {
  		need_chown = 1;
  		if (!S_ISLNK(sctx->cur_inode_mode))
  			need_chmod = 1;
  	} else {
  		ret = get_inode_info(sctx->parent_root, sctx->cur_ino,
  				NULL, NULL, &right_mode, &right_uid,
  				&right_gid, NULL);
  		if (ret < 0)
  			goto out;
  
  		if (left_uid != right_uid || left_gid != right_gid)
  			need_chown = 1;
  		if (!S_ISLNK(sctx->cur_inode_mode) && left_mode != right_mode)
  			need_chmod = 1;
  	}
  
  	if (S_ISREG(sctx->cur_inode_mode)) {
  		if (need_send_hole(sctx)) {
  			if (sctx->cur_inode_last_extent == (u64)-1 ||
  			    sctx->cur_inode_last_extent <
  			    sctx->cur_inode_size) {
  				ret = get_last_extent(sctx, (u64)-1);
  				if (ret)
  					goto out;
  			}
  			if (sctx->cur_inode_last_extent <
  			    sctx->cur_inode_size) {
  				ret = send_hole(sctx, sctx->cur_inode_size);
  				if (ret)
  					goto out;
  			}
  		}
  		ret = send_truncate(sctx, sctx->cur_ino, sctx->cur_inode_gen,
  				sctx->cur_inode_size);
  		if (ret < 0)
  			goto out;
  	}
  
  	if (need_chown) {
  		ret = send_chown(sctx, sctx->cur_ino, sctx->cur_inode_gen,
  				left_uid, left_gid);
  		if (ret < 0)
  			goto out;
  	}
  	if (need_chmod) {
  		ret = send_chmod(sctx, sctx->cur_ino, sctx->cur_inode_gen,
  				left_mode);
  		if (ret < 0)
  			goto out;
  	}
  
  	/*
  	 * If other directory inodes depended on our current directory
  	 * inode's move/rename, now do their move/rename operations.
  	 */
  	if (!is_waiting_for_move(sctx, sctx->cur_ino)) {
  		ret = apply_children_dir_moves(sctx);
  		if (ret)
  			goto out;
  		/*
  		 * Need to send that every time, no matter if it actually
  		 * changed between the two trees as we have done changes to
  		 * the inode before. If our inode is a directory and it's
  		 * waiting to be moved/renamed, we will send its utimes when
  		 * it's moved/renamed, therefore we don't need to do it here.
  		 */
  		sctx->send_progress = sctx->cur_ino + 1;
  		ret = send_utimes(sctx, sctx->cur_ino, sctx->cur_inode_gen);
  		if (ret < 0)
  			goto out;
  	}
  
  out:
  	return ret;
  }
  
  static int changed_inode(struct send_ctx *sctx,
  			 enum btrfs_compare_tree_result result)
  {
  	int ret = 0;
  	struct btrfs_key *key = sctx->cmp_key;
  	struct btrfs_inode_item *left_ii = NULL;
  	struct btrfs_inode_item *right_ii = NULL;
  	u64 left_gen = 0;
  	u64 right_gen = 0;
  
  	sctx->cur_ino = key->objectid;
  	sctx->cur_inode_new_gen = 0;
  	sctx->cur_inode_last_extent = (u64)-1;
  
  	/*
  	 * Set send_progress to current inode. This will tell all get_cur_xxx
  	 * functions that the current inode's refs are not updated yet. Later,
  	 * when process_recorded_refs is finished, it is set to cur_ino + 1.
  	 */
  	sctx->send_progress = sctx->cur_ino;
  
  	if (result == BTRFS_COMPARE_TREE_NEW ||
  	    result == BTRFS_COMPARE_TREE_CHANGED) {
  		left_ii = btrfs_item_ptr(sctx->left_path->nodes[0],
  				sctx->left_path->slots[0],
  				struct btrfs_inode_item);
  		left_gen = btrfs_inode_generation(sctx->left_path->nodes[0],
  				left_ii);
  	} else {
  		right_ii = btrfs_item_ptr(sctx->right_path->nodes[0],
  				sctx->right_path->slots[0],
  				struct btrfs_inode_item);
  		right_gen = btrfs_inode_generation(sctx->right_path->nodes[0],
  				right_ii);
  	}
  	if (result == BTRFS_COMPARE_TREE_CHANGED) {
  		right_ii = btrfs_item_ptr(sctx->right_path->nodes[0],
  				sctx->right_path->slots[0],
  				struct btrfs_inode_item);
  
  		right_gen = btrfs_inode_generation(sctx->right_path->nodes[0],
  				right_ii);
  
  		/*
  		 * The cur_ino = root dir case is special here. We can't treat
  		 * the inode as deleted+reused because it would generate a
  		 * stream that tries to delete/mkdir the root dir.
  		 */
  		if (left_gen != right_gen &&
  		    sctx->cur_ino != BTRFS_FIRST_FREE_OBJECTID)
  			sctx->cur_inode_new_gen = 1;
  	}
  
  	if (result == BTRFS_COMPARE_TREE_NEW) {
  		sctx->cur_inode_gen = left_gen;
  		sctx->cur_inode_new = 1;
  		sctx->cur_inode_deleted = 0;
  		sctx->cur_inode_size = btrfs_inode_size(
  				sctx->left_path->nodes[0], left_ii);
  		sctx->cur_inode_mode = btrfs_inode_mode(
  				sctx->left_path->nodes[0], left_ii);
  		sctx->cur_inode_rdev = btrfs_inode_rdev(
  				sctx->left_path->nodes[0], left_ii);
  		if (sctx->cur_ino != BTRFS_FIRST_FREE_OBJECTID)
  			ret = send_create_inode_if_needed(sctx);
  	} else if (result == BTRFS_COMPARE_TREE_DELETED) {
  		sctx->cur_inode_gen = right_gen;
  		sctx->cur_inode_new = 0;
  		sctx->cur_inode_deleted = 1;
  		sctx->cur_inode_size = btrfs_inode_size(
  				sctx->right_path->nodes[0], right_ii);
  		sctx->cur_inode_mode = btrfs_inode_mode(
  				sctx->right_path->nodes[0], right_ii);
  	} else if (result == BTRFS_COMPARE_TREE_CHANGED) {
  		/*
  		 * We need to do some special handling in case the inode was
  		 * reported as changed with a changed generation number. This
  		 * means that the original inode was deleted and new inode
  		 * reused the same inum. So we have to treat the old inode as
  		 * deleted and the new one as new.
  		 */
  		if (sctx->cur_inode_new_gen) {
  			/*
  			 * First, process the inode as if it was deleted.
  			 */
  			sctx->cur_inode_gen = right_gen;
  			sctx->cur_inode_new = 0;
  			sctx->cur_inode_deleted = 1;
  			sctx->cur_inode_size = btrfs_inode_size(
  					sctx->right_path->nodes[0], right_ii);
  			sctx->cur_inode_mode = btrfs_inode_mode(
  					sctx->right_path->nodes[0], right_ii);
  			ret = process_all_refs(sctx,
  					BTRFS_COMPARE_TREE_DELETED);
  			if (ret < 0)
  				goto out;
  
  			/*
  			 * Now process the inode as if it was new.
  			 */
  			sctx->cur_inode_gen = left_gen;
  			sctx->cur_inode_new = 1;
  			sctx->cur_inode_deleted = 0;
  			sctx->cur_inode_size = btrfs_inode_size(
  					sctx->left_path->nodes[0], left_ii);
  			sctx->cur_inode_mode = btrfs_inode_mode(
  					sctx->left_path->nodes[0], left_ii);
  			sctx->cur_inode_rdev = btrfs_inode_rdev(
  					sctx->left_path->nodes[0], left_ii);
  			ret = send_create_inode_if_needed(sctx);
  			if (ret < 0)
  				goto out;
  
  			ret = process_all_refs(sctx, BTRFS_COMPARE_TREE_NEW);
  			if (ret < 0)
  				goto out;
  			/*
  			 * Advance send_progress now as we did not get into
  			 * process_recorded_refs_if_needed in the new_gen case.
  			 */
  			sctx->send_progress = sctx->cur_ino + 1;
  
  			/*
  			 * Now process all extents and xattrs of the inode as if
  			 * they were all new.
  			 */
  			ret = process_all_extents(sctx);
  			if (ret < 0)
  				goto out;
  			ret = process_all_new_xattrs(sctx);
  			if (ret < 0)
  				goto out;
  		} else {
  			sctx->cur_inode_gen = left_gen;
  			sctx->cur_inode_new = 0;
  			sctx->cur_inode_new_gen = 0;
  			sctx->cur_inode_deleted = 0;
  			sctx->cur_inode_size = btrfs_inode_size(
  					sctx->left_path->nodes[0], left_ii);
  			sctx->cur_inode_mode = btrfs_inode_mode(
  					sctx->left_path->nodes[0], left_ii);
  		}
  	}
  
  out:
  	return ret;
  }
  
  /*
   * We have to process new refs before deleted refs, but compare_trees gives us
   * the new and deleted refs mixed. To fix this, we record the new/deleted refs
   * first and later process them in process_recorded_refs.
   * For the cur_inode_new_gen case, we skip recording completely because
   * changed_inode did already initiate processing of refs. The reason for this is
   * that in this case, compare_tree actually compares the refs of 2 different
   * inodes. To fix this, process_all_refs is used in changed_inode to handle all
   * refs of the right tree as deleted and all refs of the left tree as new.
   */
  static int changed_ref(struct send_ctx *sctx,
  		       enum btrfs_compare_tree_result result)
  {
  	int ret = 0;
  
  	BUG_ON(sctx->cur_ino != sctx->cmp_key->objectid);
  
  	if (!sctx->cur_inode_new_gen &&
  	    sctx->cur_ino != BTRFS_FIRST_FREE_OBJECTID) {
  		if (result == BTRFS_COMPARE_TREE_NEW)
  			ret = record_new_ref(sctx);
  		else if (result == BTRFS_COMPARE_TREE_DELETED)
  			ret = record_deleted_ref(sctx);
  		else if (result == BTRFS_COMPARE_TREE_CHANGED)
  			ret = record_changed_ref(sctx);
  	}
  
  	return ret;
  }
  
  /*
   * Process new/deleted/changed xattrs. We skip processing in the
   * cur_inode_new_gen case because changed_inode did already initiate processing
   * of xattrs. The reason is the same as in changed_ref
   */
  static int changed_xattr(struct send_ctx *sctx,
  			 enum btrfs_compare_tree_result result)
  {
  	int ret = 0;
  
  	BUG_ON(sctx->cur_ino != sctx->cmp_key->objectid);
  
  	if (!sctx->cur_inode_new_gen && !sctx->cur_inode_deleted) {
  		if (result == BTRFS_COMPARE_TREE_NEW)
  			ret = process_new_xattr(sctx);
  		else if (result == BTRFS_COMPARE_TREE_DELETED)
  			ret = process_deleted_xattr(sctx);
  		else if (result == BTRFS_COMPARE_TREE_CHANGED)
  			ret = process_changed_xattr(sctx);
  	}
  
  	return ret;
  }
  
  /*
   * Process new/deleted/changed extents. We skip processing in the
   * cur_inode_new_gen case because changed_inode did already initiate processing
   * of extents. The reason is the same as in changed_ref
   */
  static int changed_extent(struct send_ctx *sctx,
  			  enum btrfs_compare_tree_result result)
  {
  	int ret = 0;
  
  	BUG_ON(sctx->cur_ino != sctx->cmp_key->objectid);
  
  	if (!sctx->cur_inode_new_gen && !sctx->cur_inode_deleted) {
  		if (result != BTRFS_COMPARE_TREE_DELETED)
  			ret = process_extent(sctx, sctx->left_path,
  					sctx->cmp_key);
  	}
  
  	return ret;
  }
  
  static int dir_changed(struct send_ctx *sctx, u64 dir)
  {
  	u64 orig_gen, new_gen;
  	int ret;
  
  	ret = get_inode_info(sctx->send_root, dir, NULL, &new_gen, NULL, NULL,
  			     NULL, NULL);
  	if (ret)
  		return ret;
  
  	ret = get_inode_info(sctx->parent_root, dir, NULL, &orig_gen, NULL,
  			     NULL, NULL, NULL);
  	if (ret)
  		return ret;
  
  	return (orig_gen != new_gen) ? 1 : 0;
  }
  
  static int compare_refs(struct send_ctx *sctx, struct btrfs_path *path,
  			struct btrfs_key *key)
  {
  	struct btrfs_inode_extref *extref;
  	struct extent_buffer *leaf;
  	u64 dirid = 0, last_dirid = 0;
  	unsigned long ptr;
  	u32 item_size;
  	u32 cur_offset = 0;
  	int ref_name_len;
  	int ret = 0;
  
  	/* Easy case, just check this one dirid */
  	if (key->type == BTRFS_INODE_REF_KEY) {
  		dirid = key->offset;
  
  		ret = dir_changed(sctx, dirid);
  		goto out;
  	}
  
  	leaf = path->nodes[0];
  	item_size = btrfs_item_size_nr(leaf, path->slots[0]);
  	ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);
  	while (cur_offset < item_size) {
  		extref = (struct btrfs_inode_extref *)(ptr +
  						       cur_offset);
  		dirid = btrfs_inode_extref_parent(leaf, extref);
  		ref_name_len = btrfs_inode_extref_name_len(leaf, extref);
  		cur_offset += ref_name_len + sizeof(*extref);
  		if (dirid == last_dirid)
  			continue;
  		ret = dir_changed(sctx, dirid);
  		if (ret)
  			break;
  		last_dirid = dirid;
  	}
  out:
  	return ret;
  }
  
  /*
   * Updates compare related fields in sctx and simply forwards to the actual
   * changed_xxx functions.
   */
  static int changed_cb(struct btrfs_root *left_root,
  		      struct btrfs_root *right_root,
  		      struct btrfs_path *left_path,
  		      struct btrfs_path *right_path,
  		      struct btrfs_key *key,
  		      enum btrfs_compare_tree_result result,
  		      void *ctx)
  {
  	int ret = 0;
  	struct send_ctx *sctx = ctx;
  
  	if (result == BTRFS_COMPARE_TREE_SAME) {
  		if (key->type == BTRFS_INODE_REF_KEY ||
  		    key->type == BTRFS_INODE_EXTREF_KEY) {
  			ret = compare_refs(sctx, left_path, key);
  			if (!ret)
  				return 0;
  			if (ret < 0)
  				return ret;
  		} else if (key->type == BTRFS_EXTENT_DATA_KEY) {
  			return maybe_send_hole(sctx, left_path, key);
  		} else {
  			return 0;
  		}
  		result = BTRFS_COMPARE_TREE_CHANGED;
  		ret = 0;
  	}
  
  	sctx->left_path = left_path;
  	sctx->right_path = right_path;
  	sctx->cmp_key = key;
  
  	ret = finish_inode_if_needed(sctx, 0);
  	if (ret < 0)
  		goto out;
  
  	/* Ignore non-FS objects */
  	if (key->objectid == BTRFS_FREE_INO_OBJECTID ||
  	    key->objectid == BTRFS_FREE_SPACE_OBJECTID)
  		goto out;
  
  	if (key->type == BTRFS_INODE_ITEM_KEY)
  		ret = changed_inode(sctx, result);
  	else if (key->type == BTRFS_INODE_REF_KEY ||
  		 key->type == BTRFS_INODE_EXTREF_KEY)
  		ret = changed_ref(sctx, result);
  	else if (key->type == BTRFS_XATTR_ITEM_KEY)
  		ret = changed_xattr(sctx, result);
  	else if (key->type == BTRFS_EXTENT_DATA_KEY)
  		ret = changed_extent(sctx, result);
  
  out:
  	return ret;
  }
  
  static int full_send_tree(struct send_ctx *sctx)
  {
  	int ret;
  	struct btrfs_root *send_root = sctx->send_root;
  	struct btrfs_key key;
  	struct btrfs_key found_key;
  	struct btrfs_path *path;
  	struct extent_buffer *eb;
  	int slot;
  
  	path = alloc_path_for_send();
  	if (!path)
  		return -ENOMEM;
  
  	key.objectid = BTRFS_FIRST_FREE_OBJECTID;
  	key.type = BTRFS_INODE_ITEM_KEY;
  	key.offset = 0;
  
  	ret = btrfs_search_slot_for_read(send_root, &key, path, 1, 0);
  	if (ret < 0)
  		goto out;
  	if (ret)
  		goto out_finish;
  
  	while (1) {
  		eb = path->nodes[0];
  		slot = path->slots[0];
  		btrfs_item_key_to_cpu(eb, &found_key, slot);
  
  		ret = changed_cb(send_root, NULL, path, NULL,
  				&found_key, BTRFS_COMPARE_TREE_NEW, sctx);
  		if (ret < 0)
  			goto out;
  
  		key.objectid = found_key.objectid;
  		key.type = found_key.type;
  		key.offset = found_key.offset + 1;
  
  		ret = btrfs_next_item(send_root, path);
  		if (ret < 0)
  			goto out;
  		if (ret) {
  			ret  = 0;
  			break;
  		}
  	}
  
  out_finish:
  	ret = finish_inode_if_needed(sctx, 1);
  
  out:
  	btrfs_free_path(path);
  	return ret;
  }
  
  static int send_subvol(struct send_ctx *sctx)
  {
  	int ret;
  
  	if (!(sctx->flags & BTRFS_SEND_FLAG_OMIT_STREAM_HEADER)) {
  		ret = send_header(sctx);
  		if (ret < 0)
  			goto out;
  	}
  
  	ret = send_subvol_begin(sctx);
  	if (ret < 0)
  		goto out;
  
  	if (sctx->parent_root) {
  		ret = btrfs_compare_trees(sctx->send_root, sctx->parent_root,
  				changed_cb, sctx);
  		if (ret < 0)
  			goto out;
  		ret = finish_inode_if_needed(sctx, 1);
  		if (ret < 0)
  			goto out;
  	} else {
  		ret = full_send_tree(sctx);
  		if (ret < 0)
  			goto out;
  	}
  
  out:
  	free_recorded_refs(sctx);
  	return ret;
  }
  
  /*
   * If orphan cleanup did remove any orphans from a root, it means the tree
   * was modified and therefore the commit root is not the same as the current
   * root anymore. This is a problem, because send uses the commit root and
   * therefore can see inode items that don't exist in the current root anymore,
   * and for example make calls to btrfs_iget, which will do tree lookups based
   * on the current root and not on the commit root. Those lookups will fail,
   * returning a -ESTALE error, and making send fail with that error. So make
   * sure a send does not see any orphans we have just removed, and that it will
   * see the same inodes regardless of whether a transaction commit happened
   * before it started (meaning that the commit root will be the same as the
   * current root) or not.
   */
  static int ensure_commit_roots_uptodate(struct send_ctx *sctx)
  {
  	int i;
  	struct btrfs_trans_handle *trans = NULL;
  
  again:
  	if (sctx->parent_root &&
  	    sctx->parent_root->node != sctx->parent_root->commit_root)
  		goto commit_trans;
  
  	for (i = 0; i < sctx->clone_roots_cnt; i++)
  		if (sctx->clone_roots[i].root->node !=
  		    sctx->clone_roots[i].root->commit_root)
  			goto commit_trans;
  
  	if (trans)
  		return btrfs_end_transaction(trans, sctx->send_root);
  
  	return 0;
  
  commit_trans:
  	/* Use any root, all fs roots will get their commit roots updated. */
  	if (!trans) {
  		trans = btrfs_join_transaction(sctx->send_root);
  		if (IS_ERR(trans))
  			return PTR_ERR(trans);
  		goto again;
  	}
  
  	return btrfs_commit_transaction(trans, sctx->send_root);
  }
  
  static void btrfs_root_dec_send_in_progress(struct btrfs_root* root)
  {
  	spin_lock(&root->root_item_lock);
  	root->send_in_progress--;
  	/*
  	 * Not much left to do, we don't know why it's unbalanced and
  	 * can't blindly reset it to 0.
  	 */
  	if (root->send_in_progress < 0)
  		btrfs_err(root->fs_info,
  			"send_in_progres unbalanced %d root %llu",
  			root->send_in_progress, root->root_key.objectid);
  	spin_unlock(&root->root_item_lock);
  }
  
  long btrfs_ioctl_send(struct file *mnt_file, void __user *arg_)
  {
  	int ret = 0;
  	struct btrfs_root *send_root;
  	struct btrfs_root *clone_root;
  	struct btrfs_fs_info *fs_info;
  	struct btrfs_ioctl_send_args *arg = NULL;
  	struct btrfs_key key;
  	struct send_ctx *sctx = NULL;
  	u32 i;
  	u64 *clone_sources_tmp = NULL;
  	int clone_sources_to_rollback = 0;
  	int sort_clone_roots = 0;
  	int index;
  
  	if (!capable(CAP_SYS_ADMIN))
  		return -EPERM;
  
  	send_root = BTRFS_I(file_inode(mnt_file))->root;
  	fs_info = send_root->fs_info;
  
  	/*
  	 * The subvolume must remain read-only during send, protect against
  	 * making it RW. This also protects against deletion.
  	 */
  	spin_lock(&send_root->root_item_lock);
  	send_root->send_in_progress++;
  	spin_unlock(&send_root->root_item_lock);
  
  	/*
  	 * This is done when we lookup the root, it should already be complete
  	 * by the time we get here.
  	 */
  	WARN_ON(send_root->orphan_cleanup_state != ORPHAN_CLEANUP_DONE);
  
  	/*
  	 * Userspace tools do the checks and warn the user if it's
  	 * not RO.
  	 */
  	if (!btrfs_root_readonly(send_root)) {
  		ret = -EPERM;
  		goto out;
  	}
  
  	arg = memdup_user(arg_, sizeof(*arg));
  	if (IS_ERR(arg)) {
  		ret = PTR_ERR(arg);
  		arg = NULL;
  		goto out;
  	}
  
  	if (!access_ok(VERIFY_READ, arg->clone_sources,
  			sizeof(*arg->clone_sources) *
  			arg->clone_sources_count)) {
  		ret = -EFAULT;
  		goto out;
  	}
  
  	if (arg->flags & ~BTRFS_SEND_FLAG_MASK) {
  		ret = -EINVAL;
  		goto out;
  	}
  
  	sctx = kzalloc(sizeof(struct send_ctx), GFP_NOFS);
  	if (!sctx) {
  		ret = -ENOMEM;
  		goto out;
  	}
  
  	INIT_LIST_HEAD(&sctx->new_refs);
  	INIT_LIST_HEAD(&sctx->deleted_refs);
  	INIT_RADIX_TREE(&sctx->name_cache, GFP_NOFS);
  	INIT_LIST_HEAD(&sctx->name_cache_list);
  
  	sctx->flags = arg->flags;
  
  	sctx->send_filp = fget(arg->send_fd);
  	if (!sctx->send_filp) {
  		ret = -EBADF;
  		goto out;
  	}
  
  	sctx->send_root = send_root;
  	/*
  	 * Unlikely but possible, if the subvolume is marked for deletion but
  	 * is slow to remove the directory entry, send can still be started
  	 */
  	if (btrfs_root_dead(sctx->send_root)) {
  		ret = -EPERM;
  		goto out;
  	}
  
  	sctx->clone_roots_cnt = arg->clone_sources_count;
  
  	sctx->send_max_size = BTRFS_SEND_BUF_SIZE;
  	sctx->send_buf = vmalloc(sctx->send_max_size);
  	if (!sctx->send_buf) {
  		ret = -ENOMEM;
  		goto out;
  	}
  
  	sctx->read_buf = vmalloc(BTRFS_SEND_READ_SIZE);
  	if (!sctx->read_buf) {
  		ret = -ENOMEM;
  		goto out;
  	}
  
  	sctx->pending_dir_moves = RB_ROOT;
  	sctx->waiting_dir_moves = RB_ROOT;
  	sctx->orphan_dirs = RB_ROOT;
  
  	sctx->clone_roots = vzalloc(sizeof(struct clone_root) *
  			(arg->clone_sources_count + 1));
  	if (!sctx->clone_roots) {
  		ret = -ENOMEM;
  		goto out;
  	}
  
  	if (arg->clone_sources_count) {
  		clone_sources_tmp = vmalloc(arg->clone_sources_count *
  				sizeof(*arg->clone_sources));
  		if (!clone_sources_tmp) {
  			ret = -ENOMEM;
  			goto out;
  		}
  
  		ret = copy_from_user(clone_sources_tmp, arg->clone_sources,
  				arg->clone_sources_count *
  				sizeof(*arg->clone_sources));
  		if (ret) {
  			ret = -EFAULT;
  			goto out;
  		}
  
  		for (i = 0; i < arg->clone_sources_count; i++) {
  			key.objectid = clone_sources_tmp[i];
  			key.type = BTRFS_ROOT_ITEM_KEY;
  			key.offset = (u64)-1;
  
  			index = srcu_read_lock(&fs_info->subvol_srcu);
  
  			clone_root = btrfs_read_fs_root_no_name(fs_info, &key);
  			if (IS_ERR(clone_root)) {
  				srcu_read_unlock(&fs_info->subvol_srcu, index);
  				ret = PTR_ERR(clone_root);
  				goto out;
  			}
  			spin_lock(&clone_root->root_item_lock);
  			if (!btrfs_root_readonly(clone_root) ||
  			    btrfs_root_dead(clone_root)) {
  				spin_unlock(&clone_root->root_item_lock);
  				srcu_read_unlock(&fs_info->subvol_srcu, index);
  				ret = -EPERM;
  				goto out;
  			}
  			clone_root->send_in_progress++;
  			spin_unlock(&clone_root->root_item_lock);
  			srcu_read_unlock(&fs_info->subvol_srcu, index);
  
  			sctx->clone_roots[i].root = clone_root;
  			clone_sources_to_rollback = i + 1;
  		}
  		vfree(clone_sources_tmp);
  		clone_sources_tmp = NULL;
  	}
  
  	if (arg->parent_root) {
  		key.objectid = arg->parent_root;
  		key.type = BTRFS_ROOT_ITEM_KEY;
  		key.offset = (u64)-1;
  
  		index = srcu_read_lock(&fs_info->subvol_srcu);
  
  		sctx->parent_root = btrfs_read_fs_root_no_name(fs_info, &key);
  		if (IS_ERR(sctx->parent_root)) {
  			srcu_read_unlock(&fs_info->subvol_srcu, index);
  			ret = PTR_ERR(sctx->parent_root);
  			goto out;
  		}
  
  		spin_lock(&sctx->parent_root->root_item_lock);
  		sctx->parent_root->send_in_progress++;
  		if (!btrfs_root_readonly(sctx->parent_root) ||
  				btrfs_root_dead(sctx->parent_root)) {
  			spin_unlock(&sctx->parent_root->root_item_lock);
  			srcu_read_unlock(&fs_info->subvol_srcu, index);
  			ret = -EPERM;
  			goto out;
  		}
  		spin_unlock(&sctx->parent_root->root_item_lock);
  
  		srcu_read_unlock(&fs_info->subvol_srcu, index);
  	}
  
  	/*
  	 * Clones from send_root are allowed, but only if the clone source
  	 * is behind the current send position. This is checked while searching
  	 * for possible clone sources.
  	 */
  	sctx->clone_roots[sctx->clone_roots_cnt++].root = sctx->send_root;
  
  	/* We do a bsearch later */
  	sort(sctx->clone_roots, sctx->clone_roots_cnt,
  			sizeof(*sctx->clone_roots), __clone_root_cmp_sort,
  			NULL);
  	sort_clone_roots = 1;
  
  	ret = ensure_commit_roots_uptodate(sctx);
  	if (ret)
  		goto out;
  
  	current->journal_info = BTRFS_SEND_TRANS_STUB;
  	ret = send_subvol(sctx);
  	current->journal_info = NULL;
  	if (ret < 0)
  		goto out;
  
  	if (!(sctx->flags & BTRFS_SEND_FLAG_OMIT_END_CMD)) {
  		ret = begin_cmd(sctx, BTRFS_SEND_C_END);
  		if (ret < 0)
  			goto out;
  		ret = send_cmd(sctx);
  		if (ret < 0)
  			goto out;
  	}
  
  out:
  	WARN_ON(sctx && !ret && !RB_EMPTY_ROOT(&sctx->pending_dir_moves));
  	while (sctx && !RB_EMPTY_ROOT(&sctx->pending_dir_moves)) {
  		struct rb_node *n;
  		struct pending_dir_move *pm;
  
  		n = rb_first(&sctx->pending_dir_moves);
  		pm = rb_entry(n, struct pending_dir_move, node);
  		while (!list_empty(&pm->list)) {
  			struct pending_dir_move *pm2;
  
  			pm2 = list_first_entry(&pm->list,
  					       struct pending_dir_move, list);
  			free_pending_move(sctx, pm2);
  		}
  		free_pending_move(sctx, pm);
  	}
  
  	WARN_ON(sctx && !ret && !RB_EMPTY_ROOT(&sctx->waiting_dir_moves));
  	while (sctx && !RB_EMPTY_ROOT(&sctx->waiting_dir_moves)) {
  		struct rb_node *n;
  		struct waiting_dir_move *dm;
  
  		n = rb_first(&sctx->waiting_dir_moves);
  		dm = rb_entry(n, struct waiting_dir_move, node);
  		rb_erase(&dm->node, &sctx->waiting_dir_moves);
  		kfree(dm);
  	}
  
  	WARN_ON(sctx && !ret && !RB_EMPTY_ROOT(&sctx->orphan_dirs));
  	while (sctx && !RB_EMPTY_ROOT(&sctx->orphan_dirs)) {
  		struct rb_node *n;
  		struct orphan_dir_info *odi;
  
  		n = rb_first(&sctx->orphan_dirs);
  		odi = rb_entry(n, struct orphan_dir_info, node);
  		free_orphan_dir_info(sctx, odi);
  	}
  
  	if (sort_clone_roots) {
  		for (i = 0; i < sctx->clone_roots_cnt; i++)
  			btrfs_root_dec_send_in_progress(
  					sctx->clone_roots[i].root);
  	} else {
  		for (i = 0; sctx && i < clone_sources_to_rollback; i++)
  			btrfs_root_dec_send_in_progress(
  					sctx->clone_roots[i].root);
  
  		btrfs_root_dec_send_in_progress(send_root);
  	}
  	if (sctx && !IS_ERR_OR_NULL(sctx->parent_root))
  		btrfs_root_dec_send_in_progress(sctx->parent_root);
  
  	kfree(arg);
  	vfree(clone_sources_tmp);
  
  	if (sctx) {
  		if (sctx->send_filp)
  			fput(sctx->send_filp);
  
  		vfree(sctx->clone_roots);
  		vfree(sctx->send_buf);
  		vfree(sctx->read_buf);
  
  		name_cache_free(sctx);
  
  		kfree(sctx);
  	}
  
  	return ret;
  }
  