[PATCH v14.4 12/15] btrfs: dedupe: Inband in-memory only de-duplication implement

[Lu Fengqi <lufq.fnst@cn.fujitsu.com>]

From: Qu Wenruo <quwenruo@cn.fujitsu.com>

Core implement for inband de-duplication.
It reuse the async_cow_start() facility to do the calculate dedupe hash.
And use dedupe hash to do inband de-duplication at extent level.

The work flow is as below:
1) Run delalloc range for an inode
2) Calculate hash for the delalloc range at the unit of dedupe_bs
3) For hash match(duplicated) case, just increase source extent ref
   and insert file extent.
   For hash mismatch case, go through the normal cow_file_range()
   fallback, and add hash into dedupe_tree.
   Compress for hash miss case is not supported yet.

Current implement restore all dedupe hash in memory rb-tree, with LRU
behavior to control the limit.

Signed-off-by: Wang Xiaoguang <wangxg.fnst@cn.fujitsu.com>
Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
Signed-off-by: Lu Fengqi <lufq.fnst@cn.fujitsu.com>
---
 fs/btrfs/ctree.h       |   4 +-
 fs/btrfs/dedupe.h      |  18 +++
 fs/btrfs/extent-tree.c |  33 ++++-
 fs/btrfs/extent_io.c   |  10 +-
 fs/btrfs/extent_io.h   |   1 +
 fs/btrfs/file.c        |   3 +
 fs/btrfs/inode.c       | 329 ++++++++++++++++++++++++++++++++++++++++---------
 fs/btrfs/ioctl.c       |   1 +
 fs/btrfs/relocation.c  |  17 +++
 9 files changed, 350 insertions(+), 66 deletions(-)

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 965c6615d882..337d9b7cc4a3 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -116,9 +116,11 @@ static inline u32 count_max_extents(u64 size, u64 max_extent_size)
 enum btrfs_metadata_reserve_type {
 	BTRFS_RESERVE_NORMAL,
 	BTRFS_RESERVE_COMPRESS,
+	BTRFS_RESERVE_DEDUPE,
 };
 
-u64 btrfs_max_extent_size(enum btrfs_metadata_reserve_type reserve_type);
+u64 btrfs_max_extent_size(struct btrfs_inode *inode,
+			  enum btrfs_metadata_reserve_type reserve_type);
 int inode_need_compress(struct inode *inode);
 
 struct btrfs_mapping_tree {
diff --git a/fs/btrfs/dedupe.h b/fs/btrfs/dedupe.h
index 8311ee13ca83..3a15fc2069b9 100644
--- a/fs/btrfs/dedupe.h
+++ b/fs/btrfs/dedupe.h
@@ -22,6 +22,7 @@
 #include <linux/btrfs.h>
 #include <linux/wait.h>
 #include <crypto/hash.h>
+#include "btrfs_inode.h"
 
 static const int btrfs_hash_sizes[] = { 32 };
 
@@ -63,6 +64,23 @@ struct btrfs_dedupe_info {
 
 struct btrfs_trans_handle;
 
+static inline u64 btrfs_dedupe_blocksize(struct btrfs_inode *inode)
+{
+	struct btrfs_fs_info *fs_info = inode->root->fs_info;
+
+	return fs_info->dedupe_info->blocksize;
+}
+
+static inline int inode_need_dedupe(struct inode *inode)
+{
+	struct btrfs_fs_info *fs_info = BTRFS_I(inode)->root->fs_info;
+
+	if (!fs_info->dedupe_enabled)
+		return 0;
+
+	return 1;
+}
+
 static inline int btrfs_dedupe_hash_hit(struct btrfs_dedupe_hash *hash)
 {
 	return (hash && hash->bytenr);
diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 892a47b13deb..05acf9bc11df 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -38,6 +38,7 @@
 #include "math.h"
 #include "sysfs.h"
 #include "qgroup.h"
+#include "dedupe.h"
 
 #undef SCRAMBLE_DELAYED_REFS
 
@@ -2429,6 +2430,7 @@ static int run_one_delayed_ref(struct btrfs_trans_handle *trans,
 
 	if (btrfs_delayed_ref_is_head(node)) {
 		struct btrfs_delayed_ref_head *head;
+
 		/*
 		 * we've hit the end of the chain and we were supposed
 		 * to insert this extent into the tree.  But, it got
@@ -2453,6 +2455,18 @@ static int run_one_delayed_ref(struct btrfs_trans_handle *trans,
 			btrfs_pin_extent(fs_info, node->bytenr,
 					 node->num_bytes, 1);
 			if (head->is_data) {
+				/*
+				 * If insert_reserved is given, it means
+				 * a new extent is revered, then deleted
+				 * in one tran, and inc/dec get merged to 0.
+				 *
+				 * In this case, we need to remove its dedupe
+				 * hash.
+				 */
+				ret = btrfs_dedupe_del(trans, fs_info,
+						       node->bytenr);
+				if (ret < 0)
+					return ret;
 				ret = btrfs_del_csums(trans, fs_info,
 						      node->bytenr,
 						      node->num_bytes);
@@ -5916,7 +5930,7 @@ static unsigned drop_outstanding_extent(struct btrfs_inode *inode,
 	unsigned drop_inode_space = 0;
 	unsigned dropped_extents = 0;
 	unsigned num_extents;
-	u64 max_extent_size = btrfs_max_extent_size(reserve_type);
+	u64 max_extent_size = btrfs_max_extent_size(inode, reserve_type);
 
 	num_extents = count_max_extents(num_bytes, max_extent_size);
 	ASSERT(num_extents);
@@ -5985,15 +5999,17 @@ static u64 calc_csum_metadata_size(struct btrfs_inode *inode, u64 num_bytes,
 	return btrfs_calc_trans_metadata_size(fs_info, old_csums - num_csums);
 }
 
-u64 btrfs_max_extent_size(enum btrfs_metadata_reserve_type reserve_type)
+u64 btrfs_max_extent_size(struct btrfs_inode *inode,
+			  enum btrfs_metadata_reserve_type reserve_type)
 {
 	if (reserve_type == BTRFS_RESERVE_NORMAL)
 		return BTRFS_MAX_EXTENT_SIZE;
 	else if (reserve_type == BTRFS_RESERVE_COMPRESS)
 		return SZ_128K;
-
-	ASSERT(0);
-	return BTRFS_MAX_EXTENT_SIZE;
+	else if (reserve_type == BTRFS_RESERVE_DEDUPE)
+		return btrfs_dedupe_blocksize(inode);
+	else
+		return BTRFS_MAX_EXTENT_SIZE;
 }
 
 int btrfs_delalloc_reserve_metadata(struct btrfs_inode *inode, u64 num_bytes,
@@ -6009,7 +6025,7 @@ int btrfs_delalloc_reserve_metadata(struct btrfs_inode *inode, u64 num_bytes,
 	int ret = 0;
 	bool delalloc_lock = true;
 	u64 to_free = 0;
-	u64 max_extent_size = btrfs_max_extent_size(reserve_type);
+	u64 max_extent_size = btrfs_max_extent_size(inode, reserve_type);
 	unsigned dropped;
 	bool release_extra = false;
 
@@ -7122,6 +7138,11 @@ static int __btrfs_free_extent(struct btrfs_trans_handle *trans,
 		btrfs_release_path(path);
 
 		if (is_data) {
+			ret = btrfs_dedupe_del(trans, info, bytenr);
+			if (ret < 0) {
+				btrfs_abort_transaction(trans, ret);
+				goto out;
+			}
 			ret = btrfs_del_csums(trans, info, bytenr, num_bytes);
 			if (ret) {
 				btrfs_abort_transaction(trans, ret);
diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index c3601069e5b3..be97d679aaac 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -597,7 +597,7 @@ static int __clear_extent_bit(struct extent_io_tree *tree, u64 start, u64 end,
 	btrfs_debug_check_extent_io_range(tree, start, end);
 
 	if (bits & EXTENT_DELALLOC)
-		bits |= EXTENT_NORESERVE | EXTENT_COMPRESS;
+		bits |= EXTENT_NORESERVE | EXTENT_COMPRESS | EXTENT_DEDUPE;
 
 	if (delete)
 		bits |= ~EXTENT_CTLBITS;
@@ -740,7 +740,8 @@ static void adjust_one_outstanding_extent(struct inode *inode, u64 len,
 				enum btrfs_metadata_reserve_type reserve_type)
 {
 	unsigned int old_extents, new_extents;
-	u64 max_extent_size = btrfs_max_extent_size(reserve_type);
+	u64 max_extent_size = btrfs_max_extent_size(BTRFS_I(inode),
+						    reserve_type);
 
 	old_extents = div64_u64(len + max_extent_size - 1, max_extent_size);
 	new_extents = div64_u64(len + BTRFS_MAX_EXTENT_SIZE - 1,
@@ -779,7 +780,7 @@ void adjust_outstanding_extents(struct inode *inode, u64 start, u64 end,
 		 * The whole range is locked, so we can safely clear
 		 * EXTENT_COMPRESS flag.
 		 */
-		state->state &= ~EXTENT_COMPRESS;
+		state->state &= ~(EXTENT_COMPRESS | EXTENT_DEDUPE);
 		adjust_one_outstanding_extent(inode,
 				state->end - state->start + 1, reserve_type);
 		node = rb_next(node);
@@ -1561,7 +1562,8 @@ static noinline u64 find_delalloc_range(struct extent_io_tree *tree,
 		state = rb_entry(node, struct extent_state, rb_node);
 		if (found && (state->start != cur_start ||
 			      (state->state & EXTENT_BOUNDARY) ||
-			      (state->state ^ pre_state) & EXTENT_COMPRESS)) {
+			      (state->state ^ pre_state) & (EXTENT_COMPRESS |
+			       EXTENT_DEDUPE))) {
 			goto out;
 		}
 		if (!(state->state & EXTENT_DELALLOC)) {
diff --git a/fs/btrfs/extent_io.h b/fs/btrfs/extent_io.h
index 397d8958fcbc..808c90db090c 100644
--- a/fs/btrfs/extent_io.h
+++ b/fs/btrfs/extent_io.h
@@ -24,6 +24,7 @@
 #define EXTENT_CLEAR_DATA_RESV	(1U << 17)
 #define EXTENT_DELALLOC_NEW	(1U << 18)
 #define EXTENT_COMPRESS		(1U << 19)
+#define EXTENT_DEDUPE		(1U << 20)
 #define EXTENT_IOBITS		(EXTENT_LOCKED | EXTENT_WRITEBACK)
 #define EXTENT_DO_ACCOUNTING    (EXTENT_CLEAR_META_RESV | \
 				 EXTENT_CLEAR_DATA_RESV)
diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
index ea5dd2d12bb0..9ab6910af6df 100644
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -41,6 +41,7 @@
 #include "volumes.h"
 #include "qgroup.h"
 #include "compression.h"
+#include "dedupe.h"
 
 static struct kmem_cache *btrfs_inode_defrag_cachep;
 /*
@@ -1604,6 +1605,8 @@ static noinline ssize_t __btrfs_buffered_write(struct file *file,
 
 	if (inode_need_compress(inode))
 		reserve_type = BTRFS_RESERVE_COMPRESS;
+	else if (inode_need_dedupe(inode))
+		reserve_type = BTRFS_RESERVE_DEDUPE;
 
 	while (iov_iter_count(i) > 0) {
 		size_t offset = pos & (PAGE_SIZE - 1);
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 3df13530cf3f..74f6dd598a88 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -359,6 +359,8 @@ struct async_extent {
 	struct page **pages;
 	unsigned long nr_pages;
 	int compress_type;
+	int dedupe;
+	struct btrfs_dedupe_hash *hash;
 	struct list_head list;
 };
 
@@ -370,6 +372,7 @@ struct async_cow {
 	u64 end;
 	struct list_head extents;
 	struct btrfs_work work;
+	enum btrfs_metadata_reserve_type reserve_type;
 };
 
 static noinline int add_async_extent(struct async_cow *cow,
@@ -377,7 +380,8 @@ static noinline int add_async_extent(struct async_cow *cow,
 				     u64 compressed_size,
 				     struct page **pages,
 				     unsigned long nr_pages,
-				     int compress_type)
+				     int compress_type, int dedupe,
+				     struct btrfs_dedupe_hash *hash)
 {
 	struct async_extent *async_extent;
 
@@ -389,6 +393,8 @@ static noinline int add_async_extent(struct async_cow *cow,
 	async_extent->pages = pages;
 	async_extent->nr_pages = nr_pages;
 	async_extent->compress_type = compress_type;
+	async_extent->dedupe = dedupe;
+	async_extent->hash = hash;
 	list_add_tail(&async_extent->list, &cow->extents);
 	return 0;
 }
@@ -619,7 +625,7 @@ static noinline void compress_file_range(struct inode *inode,
 			 */
 			add_async_extent(async_cow, start, num_bytes,
 					total_compressed, pages, nr_pages,
-					compress_type);
+					compress_type, 0, NULL);
 
 			if (start + num_bytes < end) {
 				start += num_bytes;
@@ -665,7 +671,7 @@ static noinline void compress_file_range(struct inode *inode,
 	if (redirty)
 		extent_range_redirty_for_io(inode, start, end);
 	add_async_extent(async_cow, start, end - start + 1, 0, NULL, 0,
-			 BTRFS_COMPRESS_NONE);
+			 BTRFS_COMPRESS_NONE, 0, NULL);
 	*num_added += 1;
 
 	return;
@@ -694,6 +700,38 @@ static void free_async_extent_pages(struct async_extent *async_extent)
 	async_extent->pages = NULL;
 }
 
+static void end_dedupe_extent(struct inode *inode, u64 start,
+			      u32 len, unsigned long page_ops)
+{
+	int i;
+	unsigned int nr_pages = len / PAGE_SIZE;
+	struct page *page;
+
+	for (i = 0; i < nr_pages; i++) {
+		page = find_get_page(inode->i_mapping,
+				     start >> PAGE_SHIFT);
+		/* page should be already locked by caller */
+		if (WARN_ON(!page))
+			continue;
+
+		/* We need to do this by ourselves as we skipped IO */
+		if (page_ops & PAGE_CLEAR_DIRTY)
+			clear_page_dirty_for_io(page);
+		if (page_ops & PAGE_SET_WRITEBACK)
+			set_page_writeback(page);
+
+		end_extent_writepage(page, 0, start,
+				     start + PAGE_SIZE - 1);
+		if (page_ops & PAGE_END_WRITEBACK)
+			end_page_writeback(page);
+		if (page_ops & PAGE_UNLOCK)
+			unlock_page(page);
+
+		start += PAGE_SIZE;
+		put_page(page);
+	}
+}
+
 /*
  * phase two of compressed writeback.  This is the ordered portion
  * of the code, which only gets called in the order the work was
@@ -710,6 +748,7 @@ static noinline void submit_compressed_extents(struct inode *inode,
 	struct extent_map *em;
 	struct btrfs_root *root = BTRFS_I(inode)->root;
 	struct extent_io_tree *io_tree;
+	struct btrfs_dedupe_hash *hash;
 	int ret = 0;
 
 again:
@@ -719,6 +758,7 @@ static noinline void submit_compressed_extents(struct inode *inode,
 		list_del(&async_extent->list);
 
 		io_tree = &BTRFS_I(inode)->io_tree;
+		hash = async_extent->hash;
 
 retry:
 		/* did the compression code fall back to uncompressed IO? */
@@ -737,10 +777,12 @@ static noinline void submit_compressed_extents(struct inode *inode,
 			 * 128MB as max extent size to re-calculate number of
 			 * outstanding extents for this extent.
 			 */
-			adjust_outstanding_extents(inode, async_extent->start,
-						   async_extent->start +
-						   async_extent->ram_size - 1,
-						   BTRFS_RESERVE_COMPRESS);
+			if (!async_extent->dedupe)
+				adjust_outstanding_extents(inode,
+					async_extent->start,
+					async_extent->start +
+					async_extent->ram_size - 1,
+					BTRFS_RESERVE_COMPRESS);
 			/* allocate blocks */
 			ret = cow_file_range(inode, async_cow->locked_page,
 					     async_extent->start,
@@ -749,7 +791,7 @@ static noinline void submit_compressed_extents(struct inode *inode,
 					     async_extent->start +
 					     async_extent->ram_size - 1,
 					     &page_started, &nr_written, 0,
-					     NULL);
+					     hash);
 
 			/* JDM XXX */
 
@@ -759,15 +801,26 @@ static noinline void submit_compressed_extents(struct inode *inode,
 			 * and IO for us.  Otherwise, we need to submit
 			 * all those pages down to the drive.
 			 */
-			if (!page_started && !ret)
-				extent_write_locked_range(io_tree,
-						  inode, async_extent->start,
-						  async_extent->start +
-						  async_extent->ram_size - 1,
-						  btrfs_get_extent,
-						  WB_SYNC_ALL);
-			else if (ret)
+			if (!page_started && !ret) {
+				/* Skip IO for dedupe async_extent */
+				if (btrfs_dedupe_hash_hit(hash))
+					end_dedupe_extent(inode,
+						async_extent->start,
+						async_extent->ram_size,
+						PAGE_CLEAR_DIRTY |
+						PAGE_SET_WRITEBACK |
+						PAGE_END_WRITEBACK |
+						PAGE_UNLOCK);
+				else
+					extent_write_locked_range(io_tree,
+						inode, async_extent->start,
+						async_extent->start +
+						async_extent->ram_size - 1,
+						btrfs_get_extent,
+						WB_SYNC_ALL);
+			} else if (ret)
 				unlock_page(async_cow->locked_page);
+			kfree(hash);
 			kfree(async_extent);
 			cond_resched();
 			continue;
@@ -871,6 +924,7 @@ static noinline void submit_compressed_extents(struct inode *inode,
 			free_async_extent_pages(async_extent);
 		}
 		alloc_hint = ins.objectid + ins.offset;
+		kfree(hash);
 		kfree(async_extent);
 		cond_resched();
 	}
@@ -891,6 +945,7 @@ static noinline void submit_compressed_extents(struct inode *inode,
 				     PAGE_SET_WRITEBACK | PAGE_END_WRITEBACK |
 				     PAGE_SET_ERROR);
 	free_async_extent_pages(async_extent);
+	kfree(hash);
 	kfree(async_extent);
 	goto again;
 }
@@ -1005,13 +1060,19 @@ static noinline int cow_file_range(struct inode *inode,
 
 	while (disk_num_bytes > 0) {
 		cur_alloc_size = disk_num_bytes;
-		ret = btrfs_reserve_extent(root, cur_alloc_size, cur_alloc_size,
+		if (btrfs_dedupe_hash_hit(hash)) {
+			ins.objectid = hash->bytenr;
+			ins.offset = hash->num_bytes;
+		} else {
+			ret = btrfs_reserve_extent(root, cur_alloc_size,
+					   cur_alloc_size,
 					   fs_info->sectorsize, 0, alloc_hint,
 					   &ins, 1, 1);
-		if (ret < 0)
-			goto out_unlock;
+			if (ret < 0)
+				goto out_unlock;
+			extent_reserved = true;
+		}
 		cur_alloc_size = ins.offset;
-		extent_reserved = true;
 
 		ram_size = ins.offset;
 		em = create_io_em(inode, start, ins.offset, /* len */
@@ -1026,8 +1087,9 @@ static noinline int cow_file_range(struct inode *inode,
 			goto out_reserve;
 		free_extent_map(em);
 
-		ret = btrfs_add_ordered_extent(inode, start, ins.objectid,
-					       ram_size, cur_alloc_size, 0);
+		ret = btrfs_add_ordered_extent_dedupe(inode, start,
+				ins.objectid, cur_alloc_size, ins.offset,
+				0, hash);
 		if (ret)
 			goto out_drop_extent_cache;
 
@@ -1051,7 +1113,14 @@ static noinline int cow_file_range(struct inode *inode,
 						start + ram_size - 1, 0);
 		}
 
-		btrfs_dec_block_group_reservations(fs_info, ins.objectid);
+		/*
+		 * Hash hit didn't allocate extent, no need to dec bg
+		 * reservation.
+		 * Or we will underflow reservations and block balance.
+		 */
+		if (!btrfs_dedupe_hash_hit(hash))
+			btrfs_dec_block_group_reservations(fs_info,
+							   ins.objectid);
 
 		/* we're not doing compressed IO, don't unlock the first
 		 * page (which the caller expects to stay locked), don't
@@ -1126,6 +1195,79 @@ static noinline int cow_file_range(struct inode *inode,
 	goto out;
 }
 
+static int hash_file_ranges(struct inode *inode, u64 start, u64 end,
+			    struct async_cow *async_cow, int *num_added)
+{
+	struct btrfs_root *root = BTRFS_I(inode)->root;
+	struct btrfs_fs_info *fs_info = root->fs_info;
+	struct btrfs_dedupe_info *dedupe_info = fs_info->dedupe_info;
+	struct page *locked_page = async_cow->locked_page;
+	u16 hash_algo;
+	u64 dedupe_bs;
+	u64 cur_offset = start;
+	int ret = 0;
+
+	/* If dedupe is not enabled, don't split extent into dedupe_bs */
+	if (fs_info->dedupe_enabled && dedupe_info) {
+		dedupe_bs = dedupe_info->blocksize;
+		hash_algo = dedupe_info->hash_algo;
+	} else {
+		dedupe_bs = SZ_128M;
+		/* Just dummy, to avoid access NULL pointer */
+		hash_algo = BTRFS_DEDUPE_HASH_SHA256;
+	}
+
+	while (cur_offset < end) {
+		struct btrfs_dedupe_hash *hash = NULL;
+		u64 len;
+
+		len = min(end + 1 - cur_offset, dedupe_bs);
+		if (len < dedupe_bs)
+			goto next;
+
+		hash = btrfs_dedupe_alloc_hash(hash_algo);
+		if (!hash) {
+			ret = -ENOMEM;
+			goto out;
+		}
+		ret = btrfs_dedupe_calc_hash(fs_info, inode, cur_offset, hash);
+		if (ret < 0) {
+			kfree(hash);
+			goto out;
+		}
+
+		ret = btrfs_dedupe_search(fs_info, inode, cur_offset, hash);
+		if (ret < 0) {
+			kfree(hash);
+			goto out;
+		}
+		ret = 0;
+
+next:
+		/* Redirty the locked page if it corresponds to our extent */
+		if (page_offset(locked_page) >= start &&
+		    page_offset(locked_page) <= end)
+			__set_page_dirty_nobuffers(locked_page);
+
+		add_async_extent(async_cow, cur_offset, len, 0, NULL, 0,
+				 BTRFS_COMPRESS_NONE, 1, hash);
+		cur_offset += len;
+		(*num_added)++;
+	}
+out:
+	/*
+	 * Caller won't unlock pages, so if error happens, we must unlock
+	 * pages by ourselves.
+	 */
+	if (ret)
+		extent_clear_unlock_delalloc(inode, cur_offset,
+			end, end, NULL, EXTENT_LOCKED | EXTENT_DO_ACCOUNTING |
+			EXTENT_DELALLOC | EXTENT_DEFRAG, PAGE_UNLOCK |
+			PAGE_CLEAR_DIRTY | PAGE_SET_WRITEBACK |
+			PAGE_END_WRITEBACK | PAGE_SET_ERROR);
+	return ret;
+}
+
 /*
  * work queue call back to started compression on a file and pages
  */
@@ -1133,11 +1275,17 @@ static noinline void async_cow_start(struct btrfs_work *work)
 {
 	struct async_cow *async_cow;
 	int num_added = 0;
+	int ret = 0;
 	async_cow = container_of(work, struct async_cow, work);
 
-	compress_file_range(async_cow->inode, async_cow->locked_page,
-			    async_cow->start, async_cow->end, async_cow,
-			    &num_added);
+	if (async_cow->reserve_type == BTRFS_RESERVE_COMPRESS)
+		compress_file_range(async_cow->inode, async_cow->locked_page,
+				    async_cow->start, async_cow->end, async_cow,
+				    &num_added);
+	else
+		ret = hash_file_ranges(async_cow->inode, async_cow->start,
+				       async_cow->end, async_cow, &num_added);
+
 	if (num_added == 0) {
 		btrfs_add_delayed_iput(async_cow->inode);
 		async_cow->inode = NULL;
@@ -1190,6 +1338,7 @@ static int cow_file_range_async(struct inode *inode, struct page *locked_page,
 	struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
 	struct async_cow *async_cow;
 	struct btrfs_root *root = BTRFS_I(inode)->root;
+	struct btrfs_dedupe_info *dedupe_info = fs_info->dedupe_info;
 	unsigned long nr_pages;
 	u64 cur_end;
 
@@ -1202,10 +1351,17 @@ static int cow_file_range_async(struct inode *inode, struct page *locked_page,
 		async_cow->root = root;
 		async_cow->locked_page = locked_page;
 		async_cow->start = start;
+		async_cow->reserve_type = reserve_type;
 
 		cur_end = end;
 		if (reserve_type == BTRFS_RESERVE_COMPRESS)
 			cur_end = min(end, start + SZ_512K - 1);
+		else if (reserve_type == BTRFS_RESERVE_DEDUPE) {
+			u64 len = max_t(u64, SZ_512K, dedupe_info->blocksize);
+
+			cur_end = min(end, start + len - 1);
+		} else
+			ASSERT(0);
 
 		async_cow->end = cur_end;
 		INIT_LIST_HEAD(&async_cow->extents);
@@ -1582,29 +1738,33 @@ static int run_delalloc_range(void *private_data, struct page *locked_page,
 	int ret;
 	int force_cow = need_force_cow(inode, start, end);
 	struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree;
-	int need_compress;
 	enum btrfs_metadata_reserve_type reserve_type = BTRFS_RESERVE_NORMAL;
+	int need_compress, need_dedupe;
 
 	need_compress = test_range_bit(io_tree, start, end,
 				       EXTENT_COMPRESS, 1, NULL);
+	need_dedupe = test_range_bit(io_tree, start, end,
+				     EXTENT_DEDUPE, 1, NULL);
 	if (need_compress)
 		reserve_type = BTRFS_RESERVE_COMPRESS;
+	else if (need_dedupe)
+		reserve_type = BTRFS_RESERVE_DEDUPE;
 
 	if (BTRFS_I(inode)->flags & BTRFS_INODE_NODATACOW && !force_cow) {
-		if (need_compress)
+		if (need_compress || need_dedupe)
 			adjust_outstanding_extents(inode, start, end,
 						   reserve_type);
 
 		ret = run_delalloc_nocow(inode, locked_page, start, end,
 					 page_started, 1, nr_written);
 	} else if (BTRFS_I(inode)->flags & BTRFS_INODE_PREALLOC && !force_cow) {
-		if (need_compress)
+		if (need_compress || need_dedupe)
 			adjust_outstanding_extents(inode, start, end,
 						   reserve_type);
 
 		ret = run_delalloc_nocow(inode, locked_page, start, end,
 					 page_started, 0, nr_written);
-	} else if (!need_compress) {
+	} else if (!need_compress && !need_dedupe) {
 		ret = cow_file_range(inode, locked_page, start, end, end,
 				      page_started, nr_written, 1, NULL);
 	} else {
@@ -1635,7 +1795,9 @@ static void btrfs_split_extent_hook(void *private_data,
 
 	if (orig->state & EXTENT_COMPRESS)
 		reserve_type = BTRFS_RESERVE_COMPRESS;
-	max_extent_size = btrfs_max_extent_size(reserve_type);
+	else if (orig->state & EXTENT_DEDUPE)
+		reserve_type = BTRFS_RESERVE_DEDUPE;
+	max_extent_size = btrfs_max_extent_size(BTRFS_I(inode), reserve_type);
 
 	size = orig->end - orig->start + 1;
 	if (size > max_extent_size) {
@@ -1684,7 +1846,9 @@ static void btrfs_merge_extent_hook(void *private_data,
 
 	if (other->state & EXTENT_COMPRESS)
 		reserve_type = BTRFS_RESERVE_COMPRESS;
-	max_extent_size = btrfs_max_extent_size(reserve_type);
+	else if (other->state & EXTENT_DEDUPE)
+		reserve_type = BTRFS_RESERVE_DEDUPE;
+	max_extent_size = btrfs_max_extent_size(BTRFS_I(inode), reserve_type);
 
 	if (new->start > other->start)
 		new_size = new->end - other->start + 1;
@@ -1802,7 +1966,10 @@ static void btrfs_set_bit_hook(void *private_data,
 
 		if (*bits & EXTENT_COMPRESS)
 			reserve_type = BTRFS_RESERVE_COMPRESS;
-		max_extent_size = btrfs_max_extent_size(reserve_type);
+		else if (*bits & EXTENT_DEDUPE)
+			reserve_type = BTRFS_RESERVE_DEDUPE;
+		max_extent_size = btrfs_max_extent_size(BTRFS_I(inode),
+							reserve_type);
 		num_extents = count_max_extents(len, max_extent_size);
 
 		if (*bits & EXTENT_FIRST_DELALLOC)
@@ -1869,7 +2036,9 @@ static void btrfs_clear_bit_hook(void *private_data,
 
 		if (state->state & EXTENT_COMPRESS)
 			reserve_type = BTRFS_RESERVE_COMPRESS;
-		max_extent_size = btrfs_max_extent_size(reserve_type);
+		else if (state->state & EXTENT_DEDUPE)
+			reserve_type = BTRFS_RESERVE_DEDUPE;
+		max_extent_size = btrfs_max_extent_size(inode, reserve_type);
 		num_extents = count_max_extents(len, max_extent_size);
 
 		if (*bits & EXTENT_FIRST_DELALLOC) {
@@ -2091,13 +2260,16 @@ int btrfs_set_extent_delalloc(struct inode *inode, u64 start, u64 end,
 {
 	int ret;
 	unsigned int bits;
-	u64 max_extent_size = btrfs_max_extent_size(reserve_type);
+	u64 max_extent_size = btrfs_max_extent_size(BTRFS_I(inode),
+						    reserve_type);
 	u64 num_extents = div64_u64(end - start + max_extent_size,
 				    max_extent_size);
 
 	/* compression path */
 	if (reserve_type == BTRFS_RESERVE_COMPRESS)
 		bits = EXTENT_DELALLOC | EXTENT_COMPRESS | EXTENT_UPTODATE;
+	else if (reserve_type == BTRFS_RESERVE_DEDUPE)
+		bits = EXTENT_DELALLOC | EXTENT_DEDUPE | EXTENT_UPTODATE;
 	else
 		bits = EXTENT_DELALLOC | EXTENT_UPTODATE;
 
@@ -2131,7 +2303,8 @@ int btrfs_set_extent_defrag(struct inode *inode, u64 start, u64 end,
 {
 	int ret;
 	unsigned int bits;
-	u64 max_extent_size = btrfs_max_extent_size(reserve_type);
+	u64 max_extent_size = btrfs_max_extent_size(BTRFS_I(inode),
+						    reserve_type);
 	u64 num_extents = div64_u64(end - start + max_extent_size,
 				    max_extent_size);
 
@@ -2205,6 +2378,9 @@ static void btrfs_writepage_fixup_worker(struct btrfs_work *work)
 
 	if (inode_need_compress(inode))
 		reserve_type = BTRFS_RESERVE_COMPRESS;
+	else if (inode_need_dedupe(inode))
+		reserve_type = BTRFS_RESERVE_DEDUPE;
+
 	ret = btrfs_delalloc_reserve_space(inode, &data_reserved, page_start,
 					   PAGE_SIZE, reserve_type);
 	if (ret) {
@@ -2270,7 +2446,8 @@ static int insert_reserved_file_extent(struct btrfs_trans_handle *trans,
 				       u64 disk_bytenr, u64 disk_num_bytes,
 				       u64 num_bytes, u64 ram_bytes,
 				       u8 compression, u8 encryption,
-				       u16 other_encoding, int extent_type)
+				       u16 other_encoding, int extent_type,
+				       struct btrfs_dedupe_hash *hash)
 {
 	struct btrfs_root *root = BTRFS_I(inode)->root;
 	struct btrfs_file_extent_item *fi;
@@ -2334,16 +2511,44 @@ static int insert_reserved_file_extent(struct btrfs_trans_handle *trans,
 	ins.offset = disk_num_bytes;
 	ins.type = BTRFS_EXTENT_ITEM_KEY;
 
-	/*
-	 * Release the reserved range from inode dirty range map, as it is
-	 * already moved into delayed_ref_head
-	 */
-	ret = btrfs_qgroup_release_data(inode, file_pos, ram_bytes);
-	if (ret < 0)
-		goto out;
-	qg_released = ret;
-	ret = btrfs_alloc_reserved_file_extent(trans, root->root_key.objectid,
-			btrfs_ino(BTRFS_I(inode)), file_pos, qg_released, &ins);
+	if (btrfs_dedupe_hash_hit(hash)) {
+		/*
+		 * Hash hit won't create a new data extent, so its reserved
+		 * space won't be freed by new delayed_ref_head.
+		 * Manually free it.
+		 */
+		btrfs_free_reserved_data_space(inode, NULL, file_pos,
+					       ram_bytes);
+	} else {
+		/*
+		 * Hash miss or none-dedupe write, will create a new data
+		 * extent, we need to release the qgroup reserved data space.
+		 */
+		ret = btrfs_qgroup_release_data(inode, file_pos, ram_bytes);
+		if (ret < 0)
+			goto out;
+		qg_released = ret;
+		ret = btrfs_alloc_reserved_file_extent(trans,
+				root->root_key.objectid,
+				btrfs_ino(BTRFS_I(inode)), file_pos,
+				qg_released, &ins);
+		if (ret < 0)
+			goto out;
+	}
+
+	/* Add missed hash into dedupe tree */
+	if (hash && hash->bytenr == 0) {
+		hash->bytenr = ins.objectid;
+		hash->num_bytes = ins.offset;
+
+		/*
+		 * Here we ignore dedupe_add error, as even it failed,
+		 * it won't corrupt the filesystem. It will only only slightly
+		 * reduce dedup rate
+		 */
+		btrfs_dedupe_add(trans, root->fs_info, hash);
+	}
+
 out:
 	btrfs_free_path(path);
 
@@ -3032,6 +3237,7 @@ static int btrfs_finish_ordered_io(struct btrfs_ordered_extent *ordered_extent)
 	bool range_locked = false;
 	bool clear_new_delalloc_bytes = false;
 	enum btrfs_metadata_reserve_type reserve_type = BTRFS_RESERVE_NORMAL;
+	int hash_hit = btrfs_dedupe_hash_hit(ordered_extent->hash);
 
 	if (!test_bit(BTRFS_ORDERED_NOCOW, &ordered_extent->flags) &&
 	    !test_bit(BTRFS_ORDERED_PREALLOC, &ordered_extent->flags) &&
@@ -3119,7 +3325,8 @@ static int btrfs_finish_ordered_io(struct btrfs_ordered_extent *ordered_extent)
 	if (test_bit(BTRFS_ORDERED_COMPRESSED, &ordered_extent->flags)) {
 		compress_type = ordered_extent->compress_type;
 		reserve_type = BTRFS_RESERVE_COMPRESS;
-	}
+	} else if (ordered_extent->hash)
+		reserve_type = BTRFS_RESERVE_DEDUPE;
 
 	if (test_bit(BTRFS_ORDERED_PREALLOC, &ordered_extent->flags)) {
 		BUG_ON(compress_type);
@@ -3135,8 +3342,10 @@ static int btrfs_finish_ordered_io(struct btrfs_ordered_extent *ordered_extent)
 						ordered_extent->disk_len,
 						logical_len, logical_len,
 						compress_type, 0, 0,
-						BTRFS_FILE_EXTENT_REG);
-		if (!ret)
+						BTRFS_FILE_EXTENT_REG,
+						ordered_extent->hash);
+		/* Hash hit case doesn't reserve delalloc bytes */
+		if (!ret && !hash_hit)
 			btrfs_release_delalloc_bytes(fs_info,
 						     ordered_extent->start,
 						     ordered_extent->disk_len);
@@ -3199,8 +3408,11 @@ static int btrfs_finish_ordered_io(struct btrfs_ordered_extent *ordered_extent)
 		 * wrong we need to return the space for this ordered extent
 		 * back to the allocator.  We only free the extent in the
 		 * truncated case if we didn't write out the extent at all.
+		 *
+		 * For hash hit case, never free that extent, as it's being used
+		 * by others.
 		 */
-		if ((ret || !logical_len) &&
+		if ((ret || !logical_len) && !hash_hit &&
 		    !test_bit(BTRFS_ORDERED_NOCOW, &ordered_extent->flags) &&
 		    !test_bit(BTRFS_ORDERED_PREALLOC, &ordered_extent->flags))
 			btrfs_free_reserved_extent(fs_info,
@@ -3208,7 +3420,6 @@ static int btrfs_finish_ordered_io(struct btrfs_ordered_extent *ordered_extent)
 						   ordered_extent->disk_len, 1);
 	}
 
-
 	/*
 	 * This needs to be done to make sure anybody waiting knows we are done
 	 * updating everything for this ordered extent.
@@ -4919,6 +5130,8 @@ int btrfs_truncate_block(struct inode *inode, loff_t from, loff_t len,
 
 	if (inode_need_compress(inode))
 		reserve_type = BTRFS_RESERVE_COMPRESS;
+	else if (inode_need_dedupe(inode))
+		reserve_type = BTRFS_RESERVE_DEDUPE;
 
 	if ((offset & (blocksize - 1)) == 0 &&
 	    (!len || ((len & (blocksize - 1)) == 0)))
@@ -7838,7 +8051,8 @@ static void adjust_dio_outstanding_extents(struct inode *inode,
 					   struct btrfs_dio_data *dio_data,
 					   const u64 len)
 {
-	u64 max_extent_size = btrfs_max_extent_size(BTRFS_RESERVE_NORMAL);
+	u64 max_extent_size = btrfs_max_extent_size(BTRFS_I(inode),
+						    BTRFS_RESERVE_NORMAL);
 	unsigned int num_extents = count_max_extents(len, max_extent_size);
 
 	/*
@@ -8868,7 +9082,8 @@ static ssize_t btrfs_direct_IO(struct kiocb *iocb, struct iov_iter *iter)
 	bool wakeup = true;
 	bool relock = false;
 	ssize_t ret;
-	u64 max_extent_size = btrfs_max_extent_size(BTRFS_RESERVE_NORMAL);
+	u64 max_extent_size = btrfs_max_extent_size(BTRFS_I(inode),
+						    BTRFS_RESERVE_NORMAL);
 
 	if (check_direct_IO(fs_info, iocb, iter, offset))
 		return 0;
@@ -9216,6 +9431,9 @@ int btrfs_page_mkwrite(struct vm_fault *vmf)
 
 	if (inode_need_compress(inode))
 		reserve_type = BTRFS_RESERVE_COMPRESS;
+	else if (inode_need_dedupe(inode))
+		reserve_type = BTRFS_RESERVE_DEDUPE;
+
 	/*
 	 * Reserving delalloc space after obtaining the page lock can lead to
 	 * deadlock. For example, if a dirty page is locked by this function
@@ -10633,7 +10851,8 @@ static int __btrfs_prealloc_file_range(struct inode *inode, int mode,
 						  cur_offset, ins.objectid,
 						  ins.offset, ins.offset,
 						  ins.offset, 0, 0, 0,
-						  BTRFS_FILE_EXTENT_PREALLOC);
+						  BTRFS_FILE_EXTENT_PREALLOC,
+						  NULL);
 		if (ret) {
 			btrfs_free_reserved_extent(fs_info, ins.objectid,
 						   ins.offset, 0);
diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index e0c3f8829e52..e745052eae04 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -60,6 +60,7 @@
 #include "qgroup.h"
 #include "tree-log.h"
 #include "compression.h"
+#include "dedupe.h"
 
 #ifdef CONFIG_64BIT
 /* If we have a 32-bit userspace and 64-bit kernel, then the UAPI
diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c
index 366de2c2f86c..02a4b989a577 100644
--- a/fs/btrfs/relocation.c
+++ b/fs/btrfs/relocation.c
@@ -32,6 +32,7 @@
 #include "free-space-cache.h"
 #include "inode-map.h"
 #include "qgroup.h"
+#include "dedupe.h"
 
 /*
  * backref_node, mapping_node and tree_block start with this
@@ -3190,6 +3191,8 @@ static int relocate_file_extent_cluster(struct inode *inode,
 
 	if (inode_need_compress(inode))
 		reserve_type = BTRFS_RESERVE_COMPRESS;
+	else if (inode_need_dedupe(inode))
+		reserve_type = BTRFS_RESERVE_DEDUPE;
 
 	ra = kzalloc(sizeof(*ra), GFP_NOFS);
 	if (!ra)
@@ -4118,6 +4121,20 @@ static noinline_for_stack int relocate_block_group(struct reloc_control *rc)
 				rc->search_start = key.objectid;
 			}
 		}
+		/*
+		 * This data extent will be replaced, but normal dedupe_del()
+		 * will only happen at run_delayed_ref() time, which is too
+		 * late, so delete dedupe_hash early to prevent its ref get
+		 * increased during relocation
+		 */
+		if (rc->stage == MOVE_DATA_EXTENTS &&
+		    (flags & BTRFS_EXTENT_FLAG_DATA)) {
+			ret = btrfs_dedupe_del(trans, fs_info, key.objectid);
+			if (ret < 0) {
+				err = ret;
+				break;
+			}
+		}
 
 		btrfs_end_transaction_throttle(trans);
 		btrfs_btree_balance_dirty(fs_info);
-- 
2.13.2