Btrfs: Add support for multiple devices per filesystem

Signed-off-by: Chris Mason <chris.mason@oracle.com>

fs/btrfs/Makefile

@@ -6,7 +6,7 @@ btrfs-y := super.o ctree.o extent-tree.o print-tree.o root-tree.o dir-item.o \
 	   hash.o file-item.o inode-item.o inode-map.o disk-io.o \
 	   transaction.o bit-radix.o inode.o file.o tree-defrag.o \
 	   extent_map.o sysfs.o struct-funcs.o xattr.o ordered-data.o \
-	   extent_io.o
+	   extent_io.o volumes.o
 
 ifeq ($(CONFIG_FS_POSIX_ACL),y)
 btrfs-y += acl.o

fs/btrfs/ctree.c

@@ -70,6 +70,14 @@ void btrfs_release_path(struct btrfs_root *root, struct btrfs_path *p)
 	memset(p, 0, sizeof(*p));
 }
 
+static void add_root_to_dirty_list(struct btrfs_root *root)
+{
+	if (root->track_dirty && list_empty(&root->dirty_list)) {
+		list_add(&root->dirty_list,
+			 &root->fs_info->dirty_cowonly_roots);
+	}
+}
+
 int btrfs_copy_root(struct btrfs_trans_handle *trans,
 		      struct btrfs_root *root,
 		      struct extent_buffer *buf,
@@ -196,6 +204,7 @@ int __btrfs_cow_block(struct btrfs_trans_handle *trans,
 					  root_gen, 0, 0, 1);
 		}
 		free_extent_buffer(buf);
+		add_root_to_dirty_list(root);
 	} else {
 		root_gen = btrfs_header_generation(parent);
 		btrfs_set_node_blockptr(parent, parent_slot,
@@ -241,7 +250,7 @@ int btrfs_cow_block(struct btrfs_trans_handle *trans,
 		return 0;
 	}
 
-	search_start = buf->start & ~((u64)BTRFS_BLOCK_GROUP_SIZE - 1);
+	search_start = buf->start & ~((u64)(1024 * 1024 * 1024) - 1);
 	ret = __btrfs_cow_block(trans, root, buf, parent,
 				 parent_slot, cow_ret, search_start, 0);
 	return ret;
@@ -724,6 +733,7 @@ static int balance_level(struct btrfs_trans_handle *trans,
 		BUG_ON(ret);
 
 		root->node = child;
+		add_root_to_dirty_list(root);
 		path->nodes[level] = NULL;
 		clean_tree_block(trans, root, mid);
 		wait_on_tree_block_writeback(root, mid);
@@ -1369,6 +1379,7 @@ static int noinline insert_new_root(struct btrfs_trans_handle *trans,
 	/* the super has an extra ref to root->node */
 	free_extent_buffer(root->node);
 	root->node = c;
+	add_root_to_dirty_list(root);
 	extent_buffer_get(c);
 	path->nodes[level] = c;
 	path->slots[level] = 0;
@@ -2777,3 +2788,28 @@ int btrfs_next_leaf(struct btrfs_root *root, struct btrfs_path *path)
 	}
 	return 0;
 }
+
+int btrfs_previous_item(struct btrfs_root *root,
+			struct btrfs_path *path, u64 min_objectid,
+			int type)
+{
+	struct btrfs_key found_key;
+	struct extent_buffer *leaf;
+	int ret;
+
+	while(1) {
+		if (path->slots[0] == 0) {
+			ret = btrfs_prev_leaf(root, path);
+			if (ret != 0)
+				return ret;
+		} else {
+			path->slots[0]--;
+		}
+		leaf = path->nodes[0];
+		btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
+		if (found_key.type == type)
+			return 0;
+	}
+	return 1;
+}
+

fs/btrfs/disk-io.c

@@ -28,6 +28,7 @@
 #include "disk-io.h"
 #include "transaction.h"
 #include "btrfs_inode.h"
+#include "volumes.h"
 #include "print-tree.h"
 
 #if 0
@@ -234,6 +235,19 @@ static int btree_writepage_io_hook(struct page *page, u64 start, u64 end)
 	return 0;
 }
 
+static int btree_submit_bio_hook(struct inode *inode, int rw, struct bio *bio)
+{
+	struct btrfs_root *root = BTRFS_I(inode)->root;
+	u64 offset;
+	offset = bio->bi_sector << 9;
+	if (offset == BTRFS_SUPER_INFO_OFFSET) {
+		bio->bi_bdev = root->fs_info->sb->s_bdev;
+		submit_bio(rw, bio);
+		return 0;
+	}
+	return btrfs_map_bio(BTRFS_I(inode)->root, rw, bio);
+}
+
 static int btree_writepage(struct page *page, struct writeback_control *wbc)
 {
 	struct extent_io_tree *tree;
@@ -345,6 +359,23 @@ int readahead_tree_block(struct btrfs_root *root, u64 bytenr, u32 blocksize)
 	return ret;
 }
 
+static int close_all_devices(struct btrfs_fs_info *fs_info)
+{
+	struct list_head *list;
+	struct list_head *next;
+	struct btrfs_device *device;
+
+	list = &fs_info->devices;
+	while(!list_empty(list)) {
+		next = list->next;
+		list_del(next);
+		device = list_entry(next, struct btrfs_device, dev_list);
+		kfree(device->name);
+		kfree(device);
+	}
+	return 0;
+}
+
 struct extent_buffer *read_tree_block(struct btrfs_root *root, u64 bytenr,
 				      u32 blocksize)
 {
@@ -420,6 +451,8 @@ static int __setup_root(u32 nodesize, u32 leafsize, u32 sectorsize,
 	root->leafsize = leafsize;
 	root->stripesize = stripesize;
 	root->ref_cows = 0;
+	root->track_dirty = 0;
+
 	root->fs_info = fs_info;
 	root->objectid = objectid;
 	root->last_trans = 0;
@@ -427,6 +460,8 @@ static int __setup_root(u32 nodesize, u32 leafsize, u32 sectorsize,
 	root->last_inode_alloc = 0;
 	root->name = NULL;
 	root->in_sysfs = 0;
+
+	INIT_LIST_HEAD(&root->dirty_list);
 	memset(&root->root_key, 0, sizeof(root->root_key));
 	memset(&root->root_item, 0, sizeof(root->root_item));
 	memset(&root->defrag_progress, 0, sizeof(root->defrag_progress));
@@ -634,6 +669,10 @@ struct btrfs_root *open_ctree(struct super_block *sb)
 					       GFP_NOFS);
 	struct btrfs_fs_info *fs_info = kmalloc(sizeof(*fs_info),
 						GFP_NOFS);
+	struct btrfs_root *chunk_root = kmalloc(sizeof(struct btrfs_root),
+						GFP_NOFS);
+	struct btrfs_root *dev_root = kmalloc(sizeof(struct btrfs_root),
+					      GFP_NOFS);
 	int ret;
 	int err = -EIO;
 	struct btrfs_super_block *disk_super;
@@ -657,6 +696,12 @@ struct btrfs_root *open_ctree(struct super_block *sb)
 	fs_info->last_trans_committed = 0;
 	fs_info->tree_root = tree_root;
 	fs_info->extent_root = extent_root;
+	fs_info->chunk_root = chunk_root;
+	fs_info->dev_root = dev_root;
+	INIT_LIST_HEAD(&fs_info->dirty_cowonly_roots);
+	INIT_LIST_HEAD(&fs_info->devices);
+	btrfs_mapping_init(&fs_info->mapping_tree);
+	fs_info->last_device = &fs_info->devices;
 	fs_info->sb = sb;
 	fs_info->throttles = 0;
 	fs_info->mount_opt = 0;
@@ -714,12 +759,12 @@ struct btrfs_root *open_ctree(struct super_block *sb)
 		goto fail_iput;
 	}
 #endif
-	__setup_root(512, 512, 512, 512, tree_root,
+	__setup_root(4096, 4096, 4096, 4096, tree_root,
 		     fs_info, BTRFS_ROOT_TREE_OBJECTID);
 
 	fs_info->sb_buffer = read_tree_block(tree_root,
 					     BTRFS_SUPER_INFO_OFFSET,
-					     512);
+					     4096);
 
 	if (!fs_info->sb_buffer)
 		goto fail_iput;
@@ -730,6 +775,7 @@ struct btrfs_root *open_ctree(struct super_block *sb)
 	read_extent_buffer(fs_info->sb_buffer, fs_info->fsid,
 			   (unsigned long)btrfs_super_fsid(fs_info->sb_buffer),
 			   BTRFS_FSID_SIZE);
+
 	disk_super = &fs_info->super_copy;
 	if (!btrfs_super_root(disk_super))
 		goto fail_sb_buffer;
@@ -753,23 +799,47 @@ struct btrfs_root *open_ctree(struct super_block *sb)
 		goto fail_sb_buffer;
 	}
 
+	mutex_lock(&fs_info->fs_mutex);
+	ret = btrfs_read_sys_array(tree_root);
+	BUG_ON(ret);
+
+	blocksize = btrfs_level_size(tree_root,
+				     btrfs_super_chunk_root_level(disk_super));
+
+	__setup_root(nodesize, leafsize, sectorsize, stripesize,
+		     chunk_root, fs_info, BTRFS_CHUNK_TREE_OBJECTID);
+
+	chunk_root->node = read_tree_block(chunk_root,
+					   btrfs_super_chunk_root(disk_super),
+					   blocksize);
+	BUG_ON(!chunk_root->node);
+
+	ret = btrfs_read_chunk_tree(chunk_root);
+	BUG_ON(ret);
+
 	blocksize = btrfs_level_size(tree_root,
 				     btrfs_super_root_level(disk_super));
 
+
 	tree_root->node = read_tree_block(tree_root,
 					  btrfs_super_root(disk_super),
 					  blocksize);
 	if (!tree_root->node)
 		goto fail_sb_buffer;
 
-	mutex_lock(&fs_info->fs_mutex);
 
 	ret = find_and_setup_root(tree_root, fs_info,
 				  BTRFS_EXTENT_TREE_OBJECTID, extent_root);
-	if (ret) {
-		mutex_unlock(&fs_info->fs_mutex);
+	if (ret)
 		goto fail_tree_root;
-	}
+	extent_root->track_dirty = 1;
+
+	ret = find_and_setup_root(tree_root, fs_info,
+				  BTRFS_DEV_TREE_OBJECTID, dev_root);
+	dev_root->track_dirty = 1;
+
+	if (ret)
+		goto fail_extent_root;
 
 	btrfs_read_block_groups(extent_root);
 
@@ -777,7 +847,10 @@ struct btrfs_root *open_ctree(struct super_block *sb)
 	mutex_unlock(&fs_info->fs_mutex);
 	return tree_root;
 
+fail_extent_root:
+	free_extent_buffer(extent_root->node);
 fail_tree_root:
+	mutex_unlock(&fs_info->fs_mutex);
 	free_extent_buffer(tree_root->node);
 fail_sb_buffer:
 	free_extent_buffer(fs_info->sb_buffer);
@@ -874,6 +947,12 @@ int close_ctree(struct btrfs_root *root)
 	if (fs_info->tree_root->node)
 		free_extent_buffer(fs_info->tree_root->node);
 
+	if (root->fs_info->chunk_root->node);
+		free_extent_buffer(root->fs_info->chunk_root->node);
+
+	if (root->fs_info->dev_root->node);
+		free_extent_buffer(root->fs_info->dev_root->node);
+
 	free_extent_buffer(fs_info->sb_buffer);
 
 	btrfs_free_block_groups(root->fs_info);
@@ -901,8 +980,13 @@ int close_ctree(struct btrfs_root *root)
 		kfree(hasher);
 	}
 #endif
+	close_all_devices(fs_info);
+	btrfs_mapping_tree_free(&fs_info->mapping_tree);
+
 	kfree(fs_info->extent_root);
 	kfree(fs_info->tree_root);
+	kfree(fs_info->chunk_root);
+	kfree(fs_info->dev_root);
 	return 0;
 }
 
@@ -1016,4 +1100,5 @@ int btrfs_read_buffer(struct extent_buffer *buf)
 
 static struct extent_io_ops btree_extent_io_ops = {
 	.writepage_io_hook = btree_writepage_io_hook,
+	.submit_bio_hook = btree_submit_bio_hook,
 };

fs/btrfs/disk-io.h

@@ -20,6 +20,7 @@
 #define __DISKIO__
 
 #define BTRFS_SUPER_INFO_OFFSET (16 * 1024)
+struct btrfs_device;
 
 struct extent_buffer *read_tree_block(struct btrfs_root *root, u64 bytenr,
 				      u32 blocksize);
@@ -65,4 +66,5 @@ int btrfs_read_buffer(struct extent_buffer *buf);
 u32 btrfs_csum_data(struct btrfs_root *root, char *data, u32 seed, size_t len);
 void btrfs_csum_final(u32 crc, char *result);
 void btrfs_throttle(struct btrfs_root *root);
+int btrfs_open_device(struct btrfs_device *dev);
 #endif

fs/btrfs/extent_io.c

@@ -1706,8 +1706,8 @@ static int submit_one_bio(int rw, struct bio *bio)
 		WARN_ON(1);
 	}
 	if (tree->ops && tree->ops->submit_bio_hook)
-		tree->ops->submit_bio_hook(rw, bio);
-
+		tree->ops->submit_bio_hook(page->mapping->host, rw, bio);
+	else
 		submit_bio(rw, bio);
 	if (bio_flagged(bio, BIO_EOPNOTSUPP))
 		ret = -EOPNOTSUPP;

fs/btrfs/extent_io.h

@@ -28,7 +28,7 @@ struct extent_state;
 struct extent_io_ops {
 	int (*fill_delalloc)(struct inode *inode, u64 start, u64 end);
 	int (*writepage_io_hook)(struct page *page, u64 start, u64 end);
-	int (*submit_bio_hook)(int rw, struct bio *bio);
+	int (*submit_bio_hook)(struct inode *inode, int rw, struct bio *bio);
 	int (*readpage_io_hook)(struct page *page, u64 start, u64 end);
 	int (*readpage_end_io_hook)(struct page *page, u64 start, u64 end,
 				    struct extent_state *state);

fs/btrfs/inode.c

@@ -40,6 +40,7 @@
 #include "btrfs_inode.h"
 #include "ioctl.h"
 #include "print-tree.h"
+#include "volumes.h"
 
 struct btrfs_iget_args {
 	u64 ino;
@@ -295,20 +296,20 @@ int btrfs_clear_bit_hook(struct inode *inode, u64 start, u64 end,
 	return 0;
 }
 
-int btrfs_submit_bio_hook(int rw, struct bio *bio)
+int btrfs_submit_bio_hook(struct inode *inode, int rw, struct bio *bio)
 {
-	struct bio_vec *bvec = bio->bi_io_vec;
-	struct inode *inode = bvec->bv_page->mapping->host;
 	struct btrfs_root *root = BTRFS_I(inode)->root;
 	struct btrfs_trans_handle *trans;
 	int ret = 0;
 
-	if (rw != WRITE)
-		return 0;
+	if (rw != WRITE) {
+		goto mapit;
+	}
 
 	if (btrfs_test_opt(root, NODATASUM) ||
-	    btrfs_test_flag(inode, NODATASUM))
-		return 0;
+	    btrfs_test_flag(inode, NODATASUM)) {
+		goto mapit;
+	}
 
 	mutex_lock(&root->fs_info->fs_mutex);
 	trans = btrfs_start_transaction(root, 1);
@@ -317,7 +318,8 @@ int btrfs_submit_bio_hook(int rw, struct bio *bio)
 	ret = btrfs_end_transaction(trans, root);
 	BUG_ON(ret);
 	mutex_unlock(&root->fs_info->fs_mutex);
-	return ret;
+mapit:
+	return btrfs_map_bio(root, rw, bio);
 }
 
 int btrfs_readpage_io_hook(struct page *page, u64 start, u64 end)
@@ -406,7 +408,7 @@ void btrfs_read_locked_inode(struct inode *inode)
 	struct btrfs_path *path;
 	struct extent_buffer *leaf;
 	struct btrfs_inode_item *inode_item;
-	struct btrfs_inode_timespec *tspec;
+	struct btrfs_timespec *tspec;
 	struct btrfs_root *root = BTRFS_I(inode)->root;
 	struct btrfs_key location;
 	u64 alloc_group_block;
@@ -455,7 +457,8 @@ void btrfs_read_locked_inode(struct inode *inode)
 	BTRFS_I(inode)->flags = btrfs_inode_flags(leaf, inode_item);
 	if (!BTRFS_I(inode)->block_group) {
 		BTRFS_I(inode)->block_group = btrfs_find_block_group(root,
-						         NULL, 0, 0, 0);
+						 NULL, 0,
+						 BTRFS_BLOCK_GROUP_METADATA, 0);
 	}
 	btrfs_free_path(path);
 	inode_item = NULL;
@@ -1550,7 +1553,8 @@ static struct inode *btrfs_new_inode(struct btrfs_trans_handle *trans,
 		owner = 0;
 	else
 		owner = 1;
-	group = btrfs_find_block_group(root, group, 0, 0, owner);
+	group = btrfs_find_block_group(root, group, 0,
+				       BTRFS_BLOCK_GROUP_METADATA, owner);
 	BTRFS_I(inode)->block_group = group;
 	BTRFS_I(inode)->flags = 0;
 

fs/btrfs/print-tree.c

@@ -20,6 +20,40 @@
 #include "disk-io.h"
 #include "print-tree.h"
 
+static void print_chunk(struct extent_buffer *eb, struct btrfs_chunk *chunk)
+{
+	int num_stripes = btrfs_chunk_num_stripes(eb, chunk);
+	int i;
+	printk("\t\tchunk owner %llu type %llu num_stripes %d\n",
+	       (unsigned long long)btrfs_chunk_owner(eb, chunk),
+	       (unsigned long long)btrfs_chunk_type(eb, chunk),
+	       num_stripes);
+	for (i = 0 ; i < num_stripes ; i++) {
+		printk("\t\t\tstripe %d devid %llu offset %llu\n", i,
+		      (unsigned long long)btrfs_stripe_devid_nr(eb, chunk, i),
+		      (unsigned long long)btrfs_stripe_offset_nr(eb, chunk, i));
+	}
+}
+static void print_dev_item(struct extent_buffer *eb,
+			   struct btrfs_dev_item *dev_item)
+{
+	char *name;
+	int name_len;
+
+	name_len = btrfs_device_name_len(eb, dev_item);
+	name = kmalloc(name_len, GFP_NOFS);
+	if (name) {
+		read_extent_buffer(eb, name,
+				   (unsigned long)btrfs_device_name(dev_item),
+				   name_len);
+	}
+	printk("\t\tdev item name %.*s devid %llu "
+	       "total_bytes %llu bytes used %Lu\n", name_len, name,
+	       (unsigned long long)btrfs_device_id(eb, dev_item),
+	       (unsigned long long)btrfs_device_total_bytes(eb, dev_item),
+	       (unsigned long long)btrfs_device_bytes_used(eb, dev_item));
+	kfree(name);
+}
 void btrfs_print_leaf(struct btrfs_root *root, struct extent_buffer *l)
 {
 	int i;
@@ -34,6 +68,7 @@ void btrfs_print_leaf(struct btrfs_root *root, struct extent_buffer *l)
 	struct btrfs_key key;
 	struct btrfs_key found_key;
 	struct btrfs_extent_ref *ref;
+	struct btrfs_dev_extent *dev_extent;
 	u32 type;
 
 	printk("leaf %llu total ptrs %d free space %d\n",
@@ -106,6 +141,19 @@ void btrfs_print_leaf(struct btrfs_root *root, struct extent_buffer *l)
 			printk("\t\tblock group used %llu\n",
 			       (unsigned long long)btrfs_disk_block_group_used(l, bi));
 			break;
+		case BTRFS_CHUNK_ITEM_KEY:
+			print_chunk(l, btrfs_item_ptr(l, i, struct btrfs_chunk));
+			break;
+		case BTRFS_DEV_ITEM_KEY:
+			print_dev_item(l, btrfs_item_ptr(l, i,
+					struct btrfs_dev_item));
+			break;
+		case BTRFS_DEV_EXTENT_KEY:
+			dev_extent = btrfs_item_ptr(l, i,
+						    struct btrfs_dev_extent);
+			printk("\t\tdev extent owner %llu length %llu\n",
+			       (unsigned long long)btrfs_dev_extent_owner(l, dev_extent),
+			       (unsigned long long)btrfs_dev_extent_length(l, dev_extent));
 		};
 	}
 }

fs/btrfs/transaction.c

@@ -198,29 +198,42 @@ int btrfs_write_and_wait_transaction(struct btrfs_trans_handle *trans,
 	return werr;
 }
 
-int btrfs_commit_tree_roots(struct btrfs_trans_handle *trans,
+static int update_cowonly_root(struct btrfs_trans_handle *trans,
 			       struct btrfs_root *root)
 {
 	int ret;
-	u64 old_extent_block;
-	struct btrfs_fs_info *fs_info = root->fs_info;
-	struct btrfs_root *tree_root = fs_info->tree_root;
-	struct btrfs_root *extent_root = fs_info->extent_root;
+	u64 old_root_bytenr;
+	struct btrfs_root *tree_root = root->fs_info->tree_root;
 
-	btrfs_write_dirty_block_groups(trans, extent_root);
+	btrfs_write_dirty_block_groups(trans, root);
 	while(1) {
-		old_extent_block = btrfs_root_bytenr(&extent_root->root_item);
-		if (old_extent_block == extent_root->node->start)
+		old_root_bytenr = btrfs_root_bytenr(&root->root_item);
+		if (old_root_bytenr == root->node->start)
 			break;
-		btrfs_set_root_bytenr(&extent_root->root_item,
-				      extent_root->node->start);
-		btrfs_set_root_level(&extent_root->root_item,
-				     btrfs_header_level(extent_root->node));
+		btrfs_set_root_bytenr(&root->root_item,
+				       root->node->start);
+		btrfs_set_root_level(&root->root_item,
+				     btrfs_header_level(root->node));
 		ret = btrfs_update_root(trans, tree_root,
-					&extent_root->root_key,
-					&extent_root->root_item);
+					&root->root_key,
+					&root->root_item);
 		BUG_ON(ret);
-		btrfs_write_dirty_block_groups(trans, extent_root);
+		btrfs_write_dirty_block_groups(trans, root);
+	}
+	return 0;
+}
+
+int btrfs_commit_tree_roots(struct btrfs_trans_handle *trans,
+			    struct btrfs_root *root)
+{
+	struct btrfs_fs_info *fs_info = root->fs_info;
+	struct list_head *next;
+
+	while(!list_empty(&fs_info->dirty_cowonly_roots)) {
+		next = fs_info->dirty_cowonly_roots.next;
+		list_del_init(next);
+		root = list_entry(next, struct btrfs_root, dirty_list);
+		update_cowonly_root(trans, root);
 	}
 	return 0;
 }
@@ -616,6 +629,7 @@ int btrfs_commit_transaction(struct btrfs_trans_handle *trans,
 	unsigned long timeout = 1;
 	struct btrfs_transaction *cur_trans;
 	struct btrfs_transaction *prev_trans = NULL;
+	struct btrfs_root *chunk_root = root->fs_info->chunk_root;
 	struct list_head dirty_fs_roots;
 	struct extent_io_tree *pinned_copy;
 	DEFINE_WAIT(wait);
@@ -714,6 +728,10 @@ int btrfs_commit_transaction(struct btrfs_trans_handle *trans,
 	btrfs_set_super_root_level(&root->fs_info->super_copy,
 			   btrfs_header_level(root->fs_info->tree_root->node));
 
+	btrfs_set_super_chunk_root(&root->fs_info->super_copy,
+				   chunk_root->node->start);
+	btrfs_set_super_chunk_root_level(&root->fs_info->super_copy,
+					 btrfs_header_level(chunk_root->node));
 	write_extent_buffer(root->fs_info->sb_buffer,
 			    &root->fs_info->super_copy, 0,
 			    sizeof(root->fs_info->super_copy));

fs/btrfs/volumes.h

+/*
+ * Copyright (C) 2007 Oracle.  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_VOLUMES_
+#define __BTRFS_VOLUMES_
+struct btrfs_device {
+	struct list_head dev_list;
+	struct btrfs_root *dev_root;
+	struct btrfs_key dev_key;
+
+	struct block_device *bdev;
+
+	/* the internal btrfs device id */
+	u64 devid;
+
+	/* size of the device */
+	u64 total_bytes;
+
+	/* bytes used */
+	u64 bytes_used;
+
+	/* optimal io alignment for this device */
+	u32 io_align;
+
+	/* optimal io width for this device */
+	u32 io_width;
+
+	/* minimal io size for this device */
+	u32 sector_size;
+
+	/* the kernel device number */
+	u64 rdev;
+
+	/* type and info about this device */
+	u64 type;
+
+	/* partition number, 0 for whole dev */
+	int partition;
+
+	/* length of the name data at the end of the item */
+	int name_len;
+
+	/* physical drive uuid (or lvm uuid) */
+	u8 uuid[BTRFS_DEV_UUID_SIZE];
+
+	char *name;
+};
+
+int btrfs_alloc_dev_extent(struct btrfs_trans_handle *trans,
+			   struct btrfs_device *device,
+			   u64 owner, u64 num_bytes, u64 *start);
+int btrfs_map_block(struct btrfs_mapping_tree *map_tree,
+		    u64 logical, u64 *phys, u64 *length,
+		    struct btrfs_device **dev);
+int btrfs_read_sys_array(struct btrfs_root *root);
+int btrfs_read_chunk_tree(struct btrfs_root *root);
+int btrfs_alloc_chunk(struct btrfs_trans_handle *trans,
+		      struct btrfs_root *extent_root, u64 *start,
+		      u64 *num_bytes, u32 type);
+void btrfs_mapping_init(struct btrfs_mapping_tree *tree);
+void btrfs_mapping_tree_free(struct btrfs_mapping_tree *tree);
+int btrfs_map_bio(struct btrfs_root *root, int rw, struct bio *bio);
+#endif