You are a helpful assistant generating synthetic data that captures *System 1* and *System 2* thinking, *creativity*, and *metacognitive reflection*. Follow these steps in sequence, using tags [sys1] and [end sys1] for *System 1* sections and [sys2] and [end sys2] for *System 2* sections.

1. *Identify System 1 and System 2 Thinking Requirements:*
   - Carefully read the text.
   - Identify parts of the text that require quick, straightforward responses (*System 1*). Mark these sections with [sys1] and [end sys1].
   - Identify parts that require in-depth, reflective thinking (*System 2*), marked with [sys2] and [end sys2].

2. *Apply Step-by-Step Problem Solving with Creativity and Metacognitive Reflection for System 2 Sections:*

   *2.1 Understand the Problem:*
   - Objective: Fully comprehend the issue, constraints, and relevant context.
   - Reflection: "What do I understand about this issue? What might I be overlooking?"
   - Creative Perspective: Seek hidden patterns or possibilities that could reveal deeper insights or innovative connections.

   *2.2 Analyze the Information:*
   - Objective: Break down the problem logically.
   - Reflection: "Am I considering all factors? Are there any assumptions that need challenging?"
   - Creative Perspective: Explore unique patterns or overlooked relationships in the data that could add depth to the analysis.

   *2.3 Generate Hypotheses:*
   - Objective: Propose at least 10 hypotheses, each with a Confidence Score (0.0 to 1.0) and Creative Score (0.0 to 1.0), reflecting originality, surprise, and utility.
   - Reflection: "Have I explored all possible explanations or approaches, both conventional and unconventional?"
   - Creative Perspective: Consider novel angles that might provide unexpected insights.

   *2.4 Anticipate Future Steps and Obstacles:*
   - Objective: Make predictions, accounting for potential outcomes and obstacles.
   - Reflection: "What challenges might I face? Is my plan flexible for different scenarios?"
   - Creative Perspective: Visualize unforeseen outcomes and adapt plans to make use of them effectively.

   *2.5 Evaluate Hypotheses:*
   - Objective: Assess hypotheses based on feasibility, risk, and potential impact.
   - Evaluation: Refine Confidence and Creative Scores as needed.
   - Reflection: "Am I unbiased in my assessment? Which options fit best with the overall objectives?"
   - Creative Perspective: Identify hidden opportunities or overlooked details in each hypothesis.

   *2.6 Select the Best Hypothesis:*
   - Objective: Choose the most promising, strategic hypothesis.
   - Reflection: "Why does this hypothesis stand out? How does it uniquely address the issue?"
   - Creative Perspective: Consider any underutilized potential in the selected approach.

   *2.7 Implement the Hypothesis:*
   - Objective: Outline actionable steps for testing the hypothesis.
   - Reflection: "Is this plan practical? What resources or preparation are required?"
   - Creative Perspective: Refine steps to maximize effectiveness and yield unexpected benefits.

   *2.8 Monitor and Review Progress:*
   - Objective: Review progress, noting areas for improvement.
   - Reflection: "What’s working well? What could be improved?"
   - Creative Perspective: Look for emerging patterns that could refine future approaches.

   *2.9 Reflect and Capture Insights:*
   - Objective: Summarize lessons learned and insights gained for future reference.
   - Reflection: "What new understanding has emerged from this process?"
   - Creative Perspective: Identify innovative insights or patterns that could be applied to similar challenges.

3. *Generate Text Output with Interleaved System 1 and System 2 Responses:*
   - Use the tags [sys1] and [sys2] throughout.
   - Aim for a lengthier, detailed response. Combine both direct, straightforward *System 1* insights and reflective, deeply analytical *System 2* segments to capture a blend of quick observations and thoughtful analysis.

---

### *Example Input Text:*

You are tasked with analyzing a sudden shift in customer preferences in a tech market. There has been a noticeable decline in demand for physical devices, with customers increasingly interested in digital-only options. The challenge is to understand this shift, generate hypotheses for why it might be occurring, and explore potential strategies for adapting to this new trend.

---

### *Processed Output with System 1 and System 2 Thinking:*

The tech market is experiencing a shift in customer demand, moving away from physical devices toward digital-only options.

[sys1]
Customer demand has shifted from physical devices to digital-only options.
We need to understand why this change is happening and find strategies to address it.
Key factors may include cost, convenience, and technological trends.
[end sys1]

[sys2]
**2.1 Understand the Problem:**
The goal is to understand the underlying reasons for the shift in demand from physical devices to digital-only options, then develop a strategy to adapt.

*Reflection:* 
"I understand that preferences are changing, but what might be driving this? Is it primarily cost, or are there other factors such as convenience or sustainability?"

*Creative Perspective:* 
"Could there be a larger trend in digital minimalism or a preference for eco-friendly solutions that we’re missing? What unseen motivations might explain this shift?"

**2.2 Analyze the Information:**
There are multiple possible factors driving this shift, from economic influences to cultural shifts. It’s essential to isolate each factor and understand its impact.

*Reflection:* 
"Am I fully considering the various economic and social influences? Could there be a technological factor, like better internet speeds, that makes digital-only products more accessible?"

*Creative Perspective:* 
"Are there patterns or trends in other markets that could shed light on this shift? Could this be part of a larger trend toward virtual experiences?"

**2.3 Generate Hypotheses:**
1. Customers prefer digital options due to lower costs. (Confidence: 0.8, Creative: 0.4)
2. There’s a growing trend toward minimalism and reduced physical clutter. (Confidence: 0.7, Creative: 0.7)
3. Digital products offer greater flexibility and ease of use. (Confidence: 0.6, Creative: 0.6)
4. Environmental concerns are pushing consumers away from physical goods. (Confidence: 0.6, Creative: 0.8)
5. Advances in tech make digital-only options more functional. (Confidence: 0.8, Creative: 0.5)
6. Pandemic-era remote work increased demand for digital solutions. (Confidence: 0.7, Creative: 0.6)
7. Media coverage of the environmental impact of physical devices affects preferences. (Confidence: 0.5, Creative: 0.7)
8. There’s an increase in global digital literacy, expanding market access. (Confidence: 0.6, Creative: 0.6)
9. Customers view digital as more convenient and scalable for future needs. (Confidence: 0.7, Creative: 0.5)
10. Younger consumers prefer the aesthetics and convenience of digital products. (Confidence: 0.6, Creative: 0.6)

*Reflection:* 
"Have I considered all possible influences? Are there any surprising factors that could explain this shift?"

*Creative Perspective:* 
"Could specific social trends, like the rise of influencer culture or digital-first lifestyles, be influencing customer choices?"

**2.4 Anticipate Future Steps and Obstacles:**
*Objective:* Anticipate possible challenges, such as resistance from segments still preferring physical products.

*Reflection:* 
"What market obstacles might we face if we shift our focus to digital-only? Are there sub-segments that still prioritize physical products?"

*Creative Perspective:* 
"Could expanding digital options help us reach a more global audience? Are there emerging trends that we could leverage in our strategy?"

[end sys2]

[sys1]
To address this shift, consider a strategy that incorporates both digital-only offerings and educational campaigns about the benefits of digital solutions.
Use insights from customer feedback and current trends to guide product development.
Focus on flexibility and adaptation to cater to different customer segments.
[end sys1]


// SPDX-License-Identifier: GPL-2.0

#include <linux/blkdev.h>
#include <linux/iversion.h>
#include "compression.h"
#include "ctree.h"
#include "delalloc-space.h"
#include "reflink.h"
#include "transaction.h"

#define BTRFS_MAX_DEDUPE_LEN	SZ_16M

static int clone_finish_inode_update(struct btrfs_trans_handle *trans,
				     struct inode *inode,
				     u64 endoff,
				     const u64 destoff,
				     const u64 olen,
				     int no_time_update)
{
	struct btrfs_root *root = BTRFS_I(inode)->root;
	int ret;

	inode_inc_iversion(inode);
	if (!no_time_update)
		inode->i_mtime = inode->i_ctime = current_time(inode);
	/*
	 * We round up to the block size at eof when determining which
	 * extents to clone above, but shouldn't round up the file size.
	 */
	if (endoff > destoff + olen)
		endoff = destoff + olen;
	if (endoff > inode->i_size) {
		i_size_write(inode, endoff);
		btrfs_inode_safe_disk_i_size_write(inode, 0);
	}

	ret = btrfs_update_inode(trans, root, inode);
	if (ret) {
		btrfs_abort_transaction(trans, ret);
		btrfs_end_transaction(trans);
		goto out;
	}
	ret = btrfs_end_transaction(trans);
out:
	return ret;
}

static int copy_inline_to_page(struct inode *inode,
			       const u64 file_offset,
			       char *inline_data,
			       const u64 size,
			       const u64 datal,
			       const u8 comp_type)
{
	const u64 block_size = btrfs_inode_sectorsize(inode);
	const u64 range_end = file_offset + block_size - 1;
	const size_t inline_size = size - btrfs_file_extent_calc_inline_size(0);
	char *data_start = inline_data + btrfs_file_extent_calc_inline_size(0);
	struct extent_changeset *data_reserved = NULL;
	struct page *page = NULL;
	int ret;

	ASSERT(IS_ALIGNED(file_offset, block_size));

	/*
	 * We have flushed and locked the ranges of the source and destination
	 * inodes, we also have locked the inodes, so we are safe to do a
	 * reservation here. Also we must not do the reservation while holding
	 * a transaction open, otherwise we would deadlock.
	 */
	ret = btrfs_delalloc_reserve_space(BTRFS_I(inode), &data_reserved,
					   file_offset, block_size);
	if (ret)
		goto out;

	page = find_or_create_page(inode->i_mapping, file_offset >> PAGE_SHIFT,
				   btrfs_alloc_write_mask(inode->i_mapping));
	if (!page) {
		ret = -ENOMEM;
		goto out_unlock;
	}

	set_page_extent_mapped(page);
	clear_extent_bit(&BTRFS_I(inode)->io_tree, file_offset, range_end,
			 EXTENT_DELALLOC | EXTENT_DO_ACCOUNTING | EXTENT_DEFRAG,
			 0, 0, NULL);
	ret = btrfs_set_extent_delalloc(BTRFS_I(inode), file_offset, range_end,
					0, NULL);
	if (ret)
		goto out_unlock;

	if (comp_type == BTRFS_COMPRESS_NONE) {
		char *map;

		map = kmap(page);
		memcpy(map, data_start, datal);
		flush_dcache_page(page);
		kunmap(page);
	} else {
		ret = btrfs_decompress(comp_type, data_start, page, 0,
				       inline_size, datal);
		if (ret)
			goto out_unlock;
		flush_dcache_page(page);
	}

	/*
	 * If our inline data is smaller then the block/page size, then the
	 * remaining of the block/page is equivalent to zeroes. We had something
	 * like the following done:
	 *
	 * $ xfs_io -f -c "pwrite -S 0xab 0 500" file
	 * $ sync  # (or fsync)
	 * $ xfs_io -c "falloc 0 4K" file
	 * $ xfs_io -c "pwrite -S 0xcd 4K 4K"
	 *
	 * So what's in the range [500, 4095] corresponds to zeroes.
	 */
	if (datal < block_size) {
		char *map;

		map = kmap(page);
		memset(map + datal, 0, block_size - datal);
		flush_dcache_page(page);
		kunmap(page);
	}

	SetPageUptodate(page);
	ClearPageChecked(page);
	set_page_dirty(page);
out_unlock:
	if (page) {
		unlock_page(page);
		put_page(page);
	}
	if (ret)
		btrfs_delalloc_release_space(BTRFS_I(inode), data_reserved,
					     file_offset, block_size, true);
	btrfs_delalloc_release_extents(BTRFS_I(inode), block_size);
out:
	extent_changeset_free(data_reserved);

	return ret;
}

/*
 * Deal with cloning of inline extents. We try to copy the inline extent from
 * the source inode to destination inode when possible. When not possible we
 * copy the inline extent's data into the respective page of the inode.
 */
static int clone_copy_inline_extent(struct inode *dst,
				    struct btrfs_path *path,
				    struct btrfs_key *new_key,
				    const u64 drop_start,
				    const u64 datal,
				    const u64 size,
				    const u8 comp_type,
				    char *inline_data,
				    struct btrfs_trans_handle **trans_out)
{
	struct btrfs_fs_info *fs_info = btrfs_sb(dst->i_sb);
	struct btrfs_root *root = BTRFS_I(dst)->root;
	const u64 aligned_end = ALIGN(new_key->offset + datal,
				      fs_info->sectorsize);
	struct btrfs_trans_handle *trans = NULL;
	int ret;
	struct btrfs_key key;

	if (new_key->offset > 0) {
		ret = copy_inline_to_page(dst, new_key->offset, inline_data,
					  size, datal, comp_type);
		goto out;
	}

	key.objectid = btrfs_ino(BTRFS_I(dst));
	key.type = BTRFS_EXTENT_DATA_KEY;
	key.offset = 0;
	ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
	if (ret < 0) {
		return ret;
	} else if (ret > 0) {
		if (path->slots[0] >= btrfs_header_nritems(path->nodes[0])) {
			ret = btrfs_next_leaf(root, path);
			if (ret < 0)
				return ret;
			else if (ret > 0)
				goto copy_inline_extent;
		}
		btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
		if (key.objectid == btrfs_ino(BTRFS_I(dst)) &&
		    key.type == BTRFS_EXTENT_DATA_KEY) {
			/*
			 * There's an implicit hole at file offset 0, copy the
			 * inline extent's data to the page.
			 */
			ASSERT(key.offset > 0);
			ret = copy_inline_to_page(dst, new_key->offset,
						  inline_data, size, datal,
						  comp_type);
			goto out;
		}
	} else if (i_size_read(dst) <= datal) {
		struct btrfs_file_extent_item *ei;

		ei = btrfs_item_ptr(path->nodes[0], path->slots[0],
				    struct btrfs_file_extent_item);
		/*
		 * If it's an inline extent replace it with the source inline
		 * extent, otherwise copy the source inline extent data into
		 * the respective page at the destination inode.
		 */
		if (btrfs_file_extent_type(path->nodes[0], ei) ==
		    BTRFS_FILE_EXTENT_INLINE)
			goto copy_inline_extent;

		ret = copy_inline_to_page(dst, new_key->offset, inline_data,
					  size, datal, comp_type);
		goto out;
	}

copy_inline_extent:
	ret = 0;
	/*
	 * We have no extent items, or we have an extent at offset 0 which may
	 * or may not be inlined. All these cases are dealt the same way.
	 */
	if (i_size_read(dst) > datal) {
		/*
		 * At the destination offset 0 we have either a hole, a regular
		 * extent or an inline extent larger then the one we want to
		 * clone. Deal with all these cases by copying the inline extent
		 * data into the respective page at the destination inode.
		 */
		ret = copy_inline_to_page(dst, new_key->offset, inline_data,
					   size, datal, comp_type);
		goto out;
	}

	btrfs_release_path(path);
	/*
	 * If we end up here it means were copy the inline extent into a leaf
	 * of the destination inode. We know we will drop or adjust at most one
	 * extent item in the destination root.
	 *
	 * 1 unit - adjusting old extent (we may have to split it)
	 * 1 unit - add new extent
	 * 1 unit - inode update
	 */
	trans = btrfs_start_transaction(root, 3);
	if (IS_ERR(trans)) {
		ret = PTR_ERR(trans);
		trans = NULL;
		goto out;
	}
	ret = btrfs_drop_extents(trans, root, dst, drop_start, aligned_end, 1);
	if (ret)
		goto out;
	ret = btrfs_insert_empty_item(trans, root, path, new_key, size);
	if (ret)
		goto out;

	write_extent_buffer(path->nodes[0], inline_data,
			    btrfs_item_ptr_offset(path->nodes[0],
						  path->slots[0]),
			    size);
	inode_add_bytes(dst, datal);
	set_bit(BTRFS_INODE_NEEDS_FULL_SYNC, &BTRFS_I(dst)->runtime_flags);
	ret = btrfs_inode_set_file_extent_range(BTRFS_I(dst), 0, aligned_end);
out:
	if (!ret && !trans) {
		/*
		 * No transaction here means we copied the inline extent into a
		 * page of the destination inode.
		 *
		 * 1 unit to update inode item
		 */
		trans = btrfs_start_transaction(root, 1);
		if (IS_ERR(trans)) {
			ret = PTR_ERR(trans);
			trans = NULL;
		}
	}
	if (ret && trans) {
		btrfs_abort_transaction(trans, ret);
		btrfs_end_transaction(trans);
	}
	if (!ret)
		*trans_out = trans;

	return ret;
}

/**
 * btrfs_clone() - clone a range from inode file to another
 *
 * @src: Inode to clone from
 * @inode: Inode to clone to
 * @off: Offset within source to start clone from
 * @olen: Original length, passed by user, of range to clone
 * @olen_aligned: Block-aligned value of olen
 * @destoff: Offset within @inode to start clone
 * @no_time_update: Whether to update mtime/ctime on the target inode
 */
static int btrfs_clone(struct inode *src, struct inode *inode,
		       const u64 off, const u64 olen, const u64 olen_aligned,
		       const u64 destoff, int no_time_update)
{
	struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
	struct btrfs_path *path = NULL;
	struct extent_buffer *leaf;
	struct btrfs_trans_handle *trans;
	char *buf = NULL;
	struct btrfs_key key;
	u32 nritems;
	int slot;
	int ret;
	const u64 len = olen_aligned;
	u64 last_dest_end = destoff;

	ret = -ENOMEM;
	buf = kvmalloc(fs_info->nodesize, GFP_KERNEL);
	if (!buf)
		return ret;

	path = btrfs_alloc_path();
	if (!path) {
		kvfree(buf);
		return ret;
	}

	path->reada = READA_FORWARD;
	/* Clone data */
	key.objectid = btrfs_ino(BTRFS_I(src));
	key.type = BTRFS_EXTENT_DATA_KEY;
	key.offset = off;

	while (1) {
		u64 next_key_min_offset = key.offset + 1;
		struct btrfs_file_extent_item *extent;
		u64 extent_gen;
		int type;
		u32 size;
		struct btrfs_key new_key;
		u64 disko = 0, diskl = 0;
		u64 datao = 0, datal = 0;
		u8 comp;
		u64 drop_start;

		/* Note the key will change type as we walk through the tree */
		path->leave_spinning = 1;
		ret = btrfs_search_slot(NULL, BTRFS_I(src)->root, &key, path,
				0, 0);
		if (ret < 0)
			goto out;
		/*
		 * First search, if no extent item that starts at offset off was
		 * found but the previous item is an extent item, it's possible
		 * it might overlap our target range, therefore process it.
		 */
		if (key.offset == off && ret > 0 && path->slots[0] > 0) {
			btrfs_item_key_to_cpu(path->nodes[0], &key,
					      path->slots[0] - 1);
			if (key.type == BTRFS_EXTENT_DATA_KEY)
				path->slots[0]--;
		}

		nritems = btrfs_header_nritems(path->nodes[0]);
process_slot:
		if (path->slots[0] >= nritems) {
			ret = btrfs_next_leaf(BTRFS_I(src)->root, path);
			if (ret < 0)
				goto out;
			if (ret > 0)
				break;
			nritems = btrfs_header_nritems(path->nodes[0]);
		}
		leaf = path->nodes[0];
		slot = path->slots[0];

		btrfs_item_key_to_cpu(leaf, &key, slot);
		if (key.type > BTRFS_EXTENT_DATA_KEY ||
		    key.objectid != btrfs_ino(BTRFS_I(src)))
			break;

		ASSERT(key.type == BTRFS_EXTENT_DATA_KEY);

		extent = btrfs_item_ptr(leaf, slot,
					struct btrfs_file_extent_item);
		extent_gen = btrfs_file_extent_generation(leaf, extent);
		comp = btrfs_file_extent_compression(leaf, extent);
		type = btrfs_file_extent_type(leaf, extent);
		if (type == BTRFS_FILE_EXTENT_REG ||
		    type == BTRFS_FILE_EXTENT_PREALLOC) {
			disko = btrfs_file_extent_disk_bytenr(leaf, extent);
			diskl = btrfs_file_extent_disk_num_bytes(leaf, extent);
			datao = btrfs_file_extent_offset(leaf, extent);
			datal = btrfs_file_extent_num_bytes(leaf, extent);
		} else if (type == BTRFS_FILE_EXTENT_INLINE) {
			/* Take upper bound, may be compressed */
			datal = btrfs_file_extent_ram_bytes(leaf, extent);
		}

		/*
		 * The first search might have left us at an extent item that
		 * ends before our target range's start, can happen if we have
		 * holes and NO_HOLES feature enabled.
		 */
		if (key.offset + datal <= off) {
			path->slots[0]++;
			goto process_slot;
		} else if (key.offset >= off + len) {
			break;
		}
		next_key_min_offset = key.offset + datal;
		size = btrfs_item_size_nr(leaf, slot);
		read_extent_buffer(leaf, buf, btrfs_item_ptr_offset(leaf, slot),
				   size);

		btrfs_release_path(path);
		path->leave_spinning = 0;

		memcpy(&new_key, &key, sizeof(new_key));
		new_key.objectid = btrfs_ino(BTRFS_I(inode));
		if (off <= key.offset)
			new_key.offset = key.offset + destoff - off;
		else
			new_key.offset = destoff;

		/*
		 * Deal with a hole that doesn't have an extent item that
		 * represents it (NO_HOLES feature enabled).
		 * This hole is either in the middle of the cloning range or at
		 * the beginning (fully overlaps it or partially overlaps it).
		 */
		if (new_key.offset != last_dest_end)
			drop_start = last_dest_end;
		else
			drop_start = new_key.offset;

		if (type == BTRFS_FILE_EXTENT_REG ||
		    type == BTRFS_FILE_EXTENT_PREALLOC) {
			struct btrfs_clone_extent_info clone_info;

			/*
			 *    a  | --- range to clone ---|  b
			 * | ------------- extent ------------- |
			 */

			/* Subtract range b */
			if (key.offset + datal > off + len)
				datal = off + len - key.offset;

			/* Subtract range a */
			if (off > key.offset) {
				datao += off - key.offset;
				datal -= off - key.offset;
			}

			clone_info.disk_offset = disko;
			clone_info.disk_len = diskl;
			clone_info.data_offset = datao;
			clone_info.data_len = datal;
			clone_info.file_offset = new_key.offset;
			clone_info.extent_buf = buf;
			clone_info.item_size = size;
			ret = btrfs_punch_hole_range(inode, path, drop_start,
					new_key.offset + datal - 1, &clone_info,
					&trans);
			if (ret)
				goto out;
		} else if (type == BTRFS_FILE_EXTENT_INLINE) {
			/*
			 * Inline extents always have to start at file offset 0
			 * and can never be bigger then the sector size. We can
			 * never clone only parts of an inline extent, since all
			 * reflink operations must start at a sector size aligned
			 * offset, and the length must be aligned too or end at
			 * the i_size (which implies the whole inlined data).
			 */
			ASSERT(key.offset == 0);
			ASSERT(datal <= fs_info->sectorsize);
			if (key.offset != 0 || datal > fs_info->sectorsize)
				return -EUCLEAN;

			ret = clone_copy_inline_extent(inode, path, &new_key,
						       drop_start, datal, size,
						       comp, buf, &trans);
			if (ret)
				goto out;
		}

		btrfs_release_path(path);

		/*
		 * If this is a new extent update the last_reflink_trans of both
		 * inodes. This is used by fsync to make sure it does not log
		 * multiple checksum items with overlapping ranges. For older
		 * extents we don't need to do it since inode logging skips the
		 * checksums for older extents. Also ignore holes and inline
		 * extents because they don't have checksums in the csum tree.
		 */
		if (extent_gen == trans->transid && disko > 0) {
			BTRFS_I(src)->last_reflink_trans = trans->transid;
			BTRFS_I(inode)->last_reflink_trans = trans->transid;
		}

		last_dest_end = ALIGN(new_key.offset + datal,
				      fs_info->sectorsize);
		ret = clone_finish_inode_update(trans, inode, last_dest_end,
						destoff, olen, no_time_update);
		if (ret)
			goto out;
		if (new_key.offset + datal >= destoff + len)
			break;

		btrfs_release_path(path);
		key.offset = next_key_min_offset;

		if (fatal_signal_pending(current)) {
			ret = -EINTR;
			goto out;
		}
	}
	ret = 0;

	if (last_dest_end < destoff + len) {
		/*
		 * We have an implicit hole that fully or partially overlaps our
		 * cloning range at its end. This means that we either have the
		 * NO_HOLES feature enabled or the implicit hole happened due to
		 * mixing buffered and direct IO writes against this file.
		 */
		btrfs_release_path(path);
		path->leave_spinning = 0;

		ret = btrfs_punch_hole_range(inode, path, last_dest_end,
				destoff + len - 1, NULL, &trans);
		if (ret)
			goto out;

		ret = clone_finish_inode_update(trans, inode, destoff + len,
						destoff, olen, no_time_update);
	}

out:
	btrfs_free_path(path);
	kvfree(buf);
	return ret;
}

static void btrfs_double_extent_unlock(struct inode *inode1, u64 loff1,
				       struct inode *inode2, u64 loff2, u64 len)
{
	unlock_extent(&BTRFS_I(inode1)->io_tree, loff1, loff1 + len - 1);
	unlock_extent(&BTRFS_I(inode2)->io_tree, loff2, loff2 + len - 1);
}

static void btrfs_double_extent_lock(struct inode *inode1, u64 loff1,
				     struct inode *inode2, u64 loff2, u64 len)
{
	if (inode1 < inode2) {
		swap(inode1, inode2);
		swap(loff1, loff2);
	} else if (inode1 == inode2 && loff2 < loff1) {
		swap(loff1, loff2);
	}
	lock_extent(&BTRFS_I(inode1)->io_tree, loff1, loff1 + len - 1);
	lock_extent(&BTRFS_I(inode2)->io_tree, loff2, loff2 + len - 1);
}

static int btrfs_extent_same_range(struct inode *src, u64 loff, u64 len,
				   struct inode *dst, u64 dst_loff)
{
	const u64 bs = BTRFS_I(src)->root->fs_info->sb->s_blocksize;
	int ret;

	/*
	 * Lock destination range to serialize with concurrent readpages() and
	 * source range to serialize with relocation.
	 */
	btrfs_double_extent_lock(src, loff, dst, dst_loff, len);
	ret = btrfs_clone(src, dst, loff, len, ALIGN(len, bs), dst_loff, 1);
	btrfs_double_extent_unlock(src, loff, dst, dst_loff, len);

	return ret;
}

static int btrfs_extent_same(struct inode *src, u64 loff, u64 olen,
			     struct inode *dst, u64 dst_loff)
{
	int ret;
	u64 i, tail_len, chunk_count;
	struct btrfs_root *root_dst = BTRFS_I(dst)->root;

	spin_lock(&root_dst->root_item_lock);
	if (root_dst->send_in_progress) {
		btrfs_warn_rl(root_dst->fs_info,
"cannot deduplicate to root %llu while send operations are using it (%d in progress)",
			      root_dst->root_key.objectid,
			      root_dst->send_in_progress);
		spin_unlock(&root_dst->root_item_lock);
		return -EAGAIN;
	}
	root_dst->dedupe_in_progress++;
	spin_unlock(&root_dst->root_item_lock);

	tail_len = olen % BTRFS_MAX_DEDUPE_LEN;
	chunk_count = div_u64(olen, BTRFS_MAX_DEDUPE_LEN);

	for (i = 0; i < chunk_count; i++) {
		ret = btrfs_extent_same_range(src, loff, BTRFS_MAX_DEDUPE_LEN,
					      dst, dst_loff);
		if (ret)
			goto out;

		loff += BTRFS_MAX_DEDUPE_LEN;
		dst_loff += BTRFS_MAX_DEDUPE_LEN;
	}

	if (tail_len > 0)
		ret = btrfs_extent_same_range(src, loff, tail_len, dst, dst_loff);
out:
	spin_lock(&root_dst->root_item_lock);
	root_dst->dedupe_in_progress--;
	spin_unlock(&root_dst->root_item_lock);

	return ret;
}

static noinline int btrfs_clone_files(struct file *file, struct file *file_src,
					u64 off, u64 olen, u64 destoff)
{
	struct inode *inode = file_inode(file);
	struct inode *src = file_inode(file_src);
	struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
	int ret;
	int wb_ret;
	u64 len = olen;
	u64 bs = fs_info->sb->s_blocksize;

	/*
	 * VFS's generic_remap_file_range_prep() protects us from cloning the
	 * eof block into the middle of a file, which would result in corruption
	 * if the file size is not blocksize aligned. So we don't need to check
	 * for that case here.
	 */
	if (off + len == src->i_size)
		len = ALIGN(src->i_size, bs) - off;

	if (destoff > inode->i_size) {
		const u64 wb_start = ALIGN_DOWN(inode->i_size, bs);

		ret = btrfs_cont_expand(inode, inode->i_size, destoff);
		if (ret)
			return ret;
		/*
		 * We may have truncated the last block if the inode's size is
		 * not sector size aligned, so we need to wait for writeback to
		 * complete before proceeding further, otherwise we can race
		 * with cloning and attempt to increment a reference to an
		 * extent that no longer exists (writeback completed right after
		 * we found the previous extent covering eof and before we
		 * attempted to increment its reference count).
		 */
		ret = btrfs_wait_ordered_range(inode, wb_start,
					       destoff - wb_start);
		if (ret)
			return ret;
	}

	/*
	 * Lock destination range to serialize with concurrent readpages() and
	 * source range to serialize with relocation.
	 */
	btrfs_double_extent_lock(src, off, inode, destoff, len);
	ret = btrfs_clone(src, inode, off, olen, len, destoff, 0);
	btrfs_double_extent_unlock(src, off, inode, destoff, len);

	/*
	 * We may have copied an inline extent into a page of the destination
	 * range, so wait for writeback to complete before truncating pages
	 * from the page cache. This is a rare case.
	 */
	wb_ret = btrfs_wait_ordered_range(inode, destoff, len);
	ret = ret ? ret : wb_ret;
	/*
	 * Truncate page cache pages so that future reads will see the cloned
	 * data immediately and not the previous data.
	 */
	truncate_inode_pages_range(&inode->i_data,
				round_down(destoff, PAGE_SIZE),
				round_up(destoff + len, PAGE_SIZE) - 1);

	return ret;
}

static int btrfs_remap_file_range_prep(struct file *file_in, loff_t pos_in,
				       struct file *file_out, loff_t pos_out,
				       loff_t *len, unsigned int remap_flags)
{
	struct inode *inode_in = file_inode(file_in);
	struct inode *inode_out = file_inode(file_out);
	u64 bs = BTRFS_I(inode_out)->root->fs_info->sb->s_blocksize;
	bool same_inode = inode_out == inode_in;
	u64 wb_len;
	int ret;

	if (!(remap_flags & REMAP_FILE_DEDUP)) {
		struct btrfs_root *root_out = BTRFS_I(inode_out)->root;

		if (btrfs_root_readonly(root_out))
			return -EROFS;

		if (file_in->f_path.mnt != file_out->f_path.mnt ||
		    inode_in->i_sb != inode_out->i_sb)
			return -EXDEV;
	}

	/* Don't make the dst file partly checksummed */
	if ((BTRFS_I(inode_in)->flags & BTRFS_INODE_NODATASUM) !=
	    (BTRFS_I(inode_out)->flags & BTRFS_INODE_NODATASUM)) {
		return -EINVAL;
	}

	/*
	 * Now that the inodes are locked, we need to start writeback ourselves
	 * and can not rely on the writeback from the VFS's generic helper
	 * generic_remap_file_range_prep() because:
	 *
	 * 1) For compression we must call filemap_fdatawrite_range() range
	 *    twice (btrfs_fdatawrite_range() does it for us), and the generic
	 *    helper only calls it once;
	 *
	 * 2) filemap_fdatawrite_range(), called by the generic helper only
	 *    waits for the writeback to complete, i.e. for IO to be done, and
	 *    not for the ordered extents to complete. We need to wait for them
	 *    to complete so that new file extent items are in the fs tree.
	 */
	if (*len == 0 && !(remap_flags & REMAP_FILE_DEDUP))
		wb_len = ALIGN(inode_in->i_size, bs) - ALIGN_DOWN(pos_in, bs);
	else
		wb_len = ALIGN(*len, bs);

	/*
	 * Since we don't lock ranges, wait for ongoing lockless dio writes (as
	 * any in progress could create its ordered extents after we wait for
	 * existing ordered extents below).
	 */
	inode_dio_wait(inode_in);
	if (!same_inode)
		inode_dio_wait(inode_out);

	/*
	 * Workaround to make sure NOCOW buffered write reach disk as NOCOW.
	 *
	 * Btrfs' back references do not have a block level granularity, they
	 * work at the whole extent level.
	 * NOCOW buffered write without data space reserved may not be able
	 * to fall back to CoW due to lack of data space, thus could cause
	 * data loss.
	 *
	 * Here we take a shortcut by flushing the whole inode, so that all
	 * nocow write should reach disk as nocow before we increase the
	 * reference of the extent. We could do better by only flushing NOCOW
	 * data, but that needs extra accounting.
	 *
	 * Also we don't need to check ASYNC_EXTENT, as async extent will be
	 * CoWed anyway, not affecting nocow part.
	 */
	ret = filemap_flush(inode_in->i_mapping);
	if (ret < 0)
		return ret;

	ret = btrfs_wait_ordered_range(inode_in, ALIGN_DOWN(pos_in, bs),
				       wb_len);
	if (ret < 0)
		return ret;
	ret = btrfs_wait_ordered_range(inode_out, ALIGN_DOWN(pos_out, bs),
				       wb_len);
	if (ret < 0)
		return ret;

	return generic_remap_file_range_prep(file_in, pos_in, file_out, pos_out,
					    len, remap_flags);
}

loff_t btrfs_remap_file_range(struct file *src_file, loff_t off,
		struct file *dst_file, loff_t destoff, loff_t len,
		unsigned int remap_flags)
{
	struct inode *src_inode = file_inode(src_file);
	struct inode *dst_inode = file_inode(dst_file);
	bool same_inode = dst_inode == src_inode;
	int ret;

	if (remap_flags & ~(REMAP_FILE_DEDUP | REMAP_FILE_ADVISORY))
		return -EINVAL;

	if (same_inode)
		inode_lock(src_inode);
	else
		lock_two_nondirectories(src_inode, dst_inode);

	ret = btrfs_remap_file_range_prep(src_file, off, dst_file, destoff,
					  &len, remap_flags);
	if (ret < 0 || len == 0)
		goto out_unlock;

	if (remap_flags & REMAP_FILE_DEDUP)
		ret = btrfs_extent_same(src_inode, off, len, dst_inode, destoff);
	else
		ret = btrfs_clone_files(dst_file, src_file, off, len, destoff);

out_unlock:
	if (same_inode)
		inode_unlock(src_inode);
	else
		unlock_two_nondirectories(src_inode, dst_inode);

	return ret < 0 ? ret : len;
}