[PATCH v8 01/27] btrfs: dedupe: Introduce dedupe framework and its header

[Qu Wenruo <quwenruo@cn.fujitsu.com>]

From: Wang Xiaoguang <wangxg.fnst@cn.fujitsu.com>

Introduce the header for btrfs online(write time) de-duplication
framework and needed header.

The new de-duplication framework is going to support 2 different dedupe
methods and 1 dedupe hash.

Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
Signed-off-by: Wang Xiaoguang <wangxg.fnst@cn.fujitsu.com>
---
 fs/btrfs/ctree.h   |   5 ++
 fs/btrfs/dedupe.h  | 132 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 fs/btrfs/disk-io.c |   1 +
 3 files changed, 138 insertions(+)
 create mode 100644 fs/btrfs/dedupe.h

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 84a6a5b..022ab61 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -1860,6 +1860,11 @@ struct btrfs_fs_info {
 	struct list_head pinned_chunks;
 
 	int creating_free_space_tree;
+
+	/* Inband de-duplication related structures*/
+	unsigned int dedupe_enabled:1;
+	struct btrfs_dedupe_info *dedupe_info;
+	struct mutex dedupe_ioctl_lock;
 };
 
 struct btrfs_subvolume_writers {
diff --git a/fs/btrfs/dedupe.h b/fs/btrfs/dedupe.h
new file mode 100644
index 0000000..916039c
--- /dev/null
+++ b/fs/btrfs/dedupe.h
@@ -0,0 +1,132 @@
+/*
+ * Copyright (C) 2015 Fujitsu.  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.
+ */
+
+#ifndef __BTRFS_DEDUPE__
+#define __BTRFS_DEDUPE__
+
+#include <linux/btrfs.h>
+#include <linux/wait.h>
+#include <crypto/hash.h>
+
+/*
+ * Dedup storage backend
+ * On disk is persist storage but overhead is large
+ * In memory is fast but will lose all its hash on umount
+ */
+#define BTRFS_DEDUPE_BACKEND_INMEMORY		0
+#define BTRFS_DEDUPE_BACKEND_ONDISK		1
+#define BTRFS_DEDUPE_BACKEND_COUNT		2
+
+/* Dedup block size limit and default value */
+#define BTRFS_DEDUPE_BLOCKSIZE_MAX	(8 * 1024 * 1024)
+#define BTRFS_DEDUPE_BLOCKSIZE_MIN	(16 * 1024)
+#define BTRFS_DEDUPE_BLOCKSIZE_DEFAULT	(128 * 1024)
+
+/* Hash algorithm, only support SHA256 yet */
+#define BTRFS_DEDUPE_HASH_SHA256		0
+
+static int btrfs_dedupe_sizes[] = { 32 };
+
+/*
+ * For caller outside of dedup.c
+ *
+ * Different dedupe backends should have their own hash structure
+ */
+struct btrfs_dedupe_hash {
+	u64 bytenr;
+	u32 num_bytes;
+
+	/* last field is a variable length array of dedupe hash */
+	u8 hash[];
+};
+
+struct btrfs_dedupe_info {
+	/* dedupe blocksize */
+	u64 blocksize;
+	u16 backend;
+	u16 hash_type;
+
+	struct crypto_shash *dedupe_driver;
+	struct mutex lock;
+
+	/* following members are only used in in-memory dedupe mode */
+	struct rb_root hash_root;
+	struct rb_root bytenr_root;
+	struct list_head lru_list;
+	u64 limit_nr;
+	u64 current_nr;
+};
+
+struct btrfs_trans_handle;
+
+static inline int btrfs_dedupe_hash_hit(struct btrfs_dedupe_hash *hash)
+{
+	return (hash && hash->bytenr);
+}
+
+int btrfs_dedupe_hash_size(u16 type);
+struct btrfs_dedupe_hash *btrfs_dedupe_alloc_hash(u16 type);
+
+/*
+ * Initial inband dedupe info
+ * Called at dedupe enable time.
+ */
+int btrfs_dedupe_enable(struct btrfs_fs_info *fs_info, u16 type, u16 backend,
+			u64 blocksize, u64 limit_nr);
+
+/*
+ * Disable dedupe and invalidate all its dedupe data.
+ * Called at dedupe disable time.
+ */
+int btrfs_dedupe_disable(struct btrfs_fs_info *fs_info);
+
+/*
+ * Calculate hash for dedup.
+ * Caller must ensure [start, start + dedupe_bs) has valid data.
+ */
+int btrfs_dedupe_calc_hash(struct btrfs_fs_info *fs_info,
+			   struct inode *inode, u64 start,
+			   struct btrfs_dedupe_hash *hash);
+
+/*
+ * Search for duplicated extents by calculated hash
+ * Caller must call btrfs_dedupe_calc_hash() first to get the hash.
+ *
+ * @inode: the inode for we are writing
+ * @file_pos: offset inside the inode
+ * As we will increase extent ref immediately after a hash match,
+ * we need @file_pos and @inode in this case.
+ *
+ * Return > 0 for a hash match, and the extent ref will be
+ * *INCREASED*, and hash->bytenr/num_bytes will record the existing
+ * extent data.
+ * Return 0 for a hash miss. Nothing is done
+ */
+int btrfs_dedupe_search(struct btrfs_fs_info *fs_info,
+			struct inode *inode, u64 file_pos,
+			struct btrfs_dedupe_hash *hash);
+
+/* Add a dedupe hash into dedupe info */
+int btrfs_dedupe_add(struct btrfs_trans_handle *trans,
+		     struct btrfs_fs_info *fs_info,
+		     struct btrfs_dedupe_hash *hash);
+
+/* Remove a dedupe hash from dedupe info */
+int btrfs_dedupe_del(struct btrfs_trans_handle *trans,
+		     struct btrfs_fs_info *fs_info, u64 bytenr);
+#endif
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index c95e3ce..3cf4c11 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -2584,6 +2584,7 @@ int open_ctree(struct super_block *sb,
 	mutex_init(&fs_info->reloc_mutex);
 	mutex_init(&fs_info->delalloc_root_mutex);
 	mutex_init(&fs_info->cleaner_delayed_iput_mutex);
+	mutex_init(&fs_info->dedupe_ioctl_lock);
 	seqlock_init(&fs_info->profiles_lock);
 
 	INIT_LIST_HEAD(&fs_info->dirty_cowonly_roots);
-- 
2.7.3