Patchwork [U-Boot,v3] Introduced btrfs file-system with btrload command

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Submitter Adnan Ali
Date Feb. 15, 2013, 12:10 p.m.
Message ID <1360930249-11952-2-git-send-email-adnan.ali@codethink.co.uk>
Download mbox | patch
Permalink /patch/220723/
State Superseded
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Comments

Adnan Ali - Feb. 15, 2013, 12:10 p.m.
Introduces btrfs file-system to read file
from volume/sub-volumes with btrload command. This
implementation has read-only support.
This btrfs implementation is based on syslinux btrfs
code, commit 269ebc845ebc8b46ef4b0be7fa0005c7fdb95b8d.

Signed-off-by: Adnan Ali <adnan.ali@codethink.co.uk>
---
 Makefile                   |    1 +
 common/Makefile            |    1 +
 common/cmd_btr.c           |   53 +++
 fs/btrfs/Makefile          |   51 ++
 fs/btrfs/btrfs.c           | 1131 ++++++++++++++++++++++++++++++++++++++++++++
 fs/fs.c                    |   86 +++-
 include/btrfs.h            |  398 ++++++++++++++++
 include/config_fallbacks.h |    4 +
 include/crc32c.h           |   48 ++
 include/fs.h               |    1 +
 10 files changed, 1769 insertions(+), 5 deletions(-)
 create mode 100644 common/cmd_btr.c
 create mode 100644 fs/btrfs/Makefile
 create mode 100644 fs/btrfs/btrfs.c
 create mode 100644 include/btrfs.h
 create mode 100644 include/crc32c.h

Patch

diff --git a/Makefile b/Makefile
index 3305e8c..cc35e7b 100644
--- a/Makefile
+++ b/Makefile
@@ -261,6 +261,7 @@  endif
 LIBS-$(CONFIG_OF_EMBED) += dts/libdts.o
 LIBS-y += arch/$(ARCH)/lib/lib$(ARCH).o
 LIBS-y += fs/libfs.o \
+        fs/btrfs/libbtrfs.o \
 	fs/cbfs/libcbfs.o \
 	fs/cramfs/libcramfs.o \
 	fs/ext4/libext4fs.o \
diff --git a/common/Makefile b/common/Makefile
index 54fcc81..093dd35 100644
--- a/common/Makefile
+++ b/common/Makefile
@@ -73,6 +73,7 @@  COBJS-$(CONFIG_CMD_BEDBUG) += bedbug.o cmd_bedbug.o
 COBJS-$(CONFIG_CMD_BMP) += cmd_bmp.o
 COBJS-$(CONFIG_CMD_BOOTLDR) += cmd_bootldr.o
 COBJS-$(CONFIG_CMD_BOOTSTAGE) += cmd_bootstage.o
+COBJS-$(CONFIG_CMD_BTR) += cmd_btr.o
 COBJS-$(CONFIG_CMD_CACHE) += cmd_cache.o
 COBJS-$(CONFIG_CMD_CBFS) += cmd_cbfs.o
 COBJS-$(CONFIG_CMD_CONSOLE) += cmd_console.o
diff --git a/common/cmd_btr.c b/common/cmd_btr.c
new file mode 100644
index 0000000..faea625
--- /dev/null
+++ b/common/cmd_btr.c
@@ -0,0 +1,53 @@ 
+/*
+ * (C) Copyright 2013 Codethink Limited
+ * Btrfs port to Uboot by
+ * Adnan Ali <adnan.ali@codethink.co.uk>
+ * See file CREDITS for list of people who contributed to this
+ * project.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of
+ * the License, or (at your option) any later version.
+ *
+ * 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 02111-1307 USA
+ */
+
+/*
+ * Boot support
+ */
+#include <fs.h>
+#include <btrfs.h>
+
+char subvolname[MAX_SUBVOL_NAME];
+
+int do_btr_fsload(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
+{
+	if (argc > 5)
+		strcpy(subvolname, argv[5]);
+	else
+		strcpy(subvolname, "");
+
+	return do_load(cmdtp, flag, argc, argv, FS_TYPE_BTR, 16);
+}
+
+
+U_BOOT_CMD(
+	btrload,        7,      0,      do_btr_fsload,
+	"load binary file from a btr filesystem",
+	"<interface> [<dev[:part]>]  <addr> <filename> [subvol_name]\n"
+	"    - Load binary file 'filename' from 'dev' on 'interface'\n"
+	"      to address 'addr' from better filesystem.\n"
+	"      the load stops on end of file.\n"
+	"      subvol_name is used read that file from this subvolume.\n"
+	"      All numeric parameters are assumed to be hex."
+);
+
diff --git a/fs/btrfs/Makefile b/fs/btrfs/Makefile
new file mode 100644
index 0000000..a9e2021
--- /dev/null
+++ b/fs/btrfs/Makefile
@@ -0,0 +1,51 @@ 
+#
+# (C) Copyright 2006
+# Wolfgang Denk, DENX Software Engineering, wd@denx.de.
+#
+# (C) Copyright 2003
+# Pavel Bartusek, Sysgo Real-Time Solutions AG, pba@sysgo.de
+#
+#
+# See file CREDITS for list of people who contributed to this
+# project.
+#
+# This program is free software; you can redistribute it and/or
+# modify it under the terms of the GNU General Public License as
+# published by the Free Software Foundation; either version 2 of
+# the License, or (at your option) any later version.
+#
+# 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 02111-1307 USA
+#
+
+include $(TOPDIR)/config.mk
+
+LIB	= $(obj)libbtrfs.o
+
+AOBJS	=
+COBJS-$(CONFIG_FS_BTR) := btrfs.o
+
+SRCS	:= $(AOBJS:.o=.S) $(COBJS-y:.o=.c)
+OBJS	:= $(addprefix $(obj),$(AOBJS) $(COBJS-y))
+
+
+all:	$(LIB) $(AOBJS)
+
+$(LIB):	$(obj).depend $(OBJS)
+	$(call cmd_link_o_target, $(OBJS))
+
+#########################################################################
+
+# defines $(obj).depend target
+include $(SRCTREE)/rules.mk
+
+sinclude $(obj).depend
+
+#########################################################################
diff --git a/fs/btrfs/btrfs.c b/fs/btrfs/btrfs.c
new file mode 100644
index 0000000..9568042
--- /dev/null
+++ b/fs/btrfs/btrfs.c
@@ -0,0 +1,1131 @@ 
+/*
+ * (C) Copyright 2013 Codethink Limited
+ * Btrfs port to Uboot by
+ * Adnan Ali <adnan.ali@codethink.co.uk>
+
+ * btrfs.c -- readonly btrfs support for syslinux
+ * Some data structures are derivated from btrfs-tools-0.19 ctree.h
+ * Copyright 2009 Intel Corporation; author: alek.du@intel.com
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, Inc., 53 Temple Place Ste 330,
+ * Boston MA 02111-1307, USA; either version 2 of the License, or
+ * (at your option) any later version; incorporated herein by reference.
+ *
+ */
+
+#include <linux/stat.h>
+#include <command.h>
+#include <asm/byteorder.h>
+#include <linux/compiler.h>
+#include <common.h>
+#include <config.h>
+#include <fs.h>
+#include <btrfs.h>
+
+unsigned long btr_part_offset;
+/* Actual file structures (we don't have malloc yet...) */
+struct file files[MAX_OPEN];
+static u32 btrfs_crc32_table[256]; 
+static block_dev_desc_t *btrfs_block_dev_desc;
+static disk_partition_t *part_info;
+struct inode parent_inode;
+extern char subvolname[MAX_SUBVOL_NAME];
+
+static void btrfs_init_crc32c(void)
+{
+    /* Bit-reflected CRC32C polynomial */
+    crc32c_init(btrfs_crc32_table, 0x82F63B78);
+}
+
+static inline u32 crc32c_le(u32 crc, const char *data, size_t length)
+{
+    return crc32c_cal(crc, data, length, btrfs_crc32_table);
+} 
+
+void btrfs_set_blk_dev(block_dev_desc_t *rbdd, disk_partition_t *info)
+{
+        btrfs_block_dev_desc = rbdd;
+        part_info = info;
+        btr_part_offset = info->start;
+}
+
+
+/* compare function used for bin_search */
+typedef int (*cmp_func)(void *ptr1, void *ptr2);
+
+static int bin_search(void *ptr, int item_size, void *cmp_item, cmp_func func,
+			      int min, int max, int *slot)
+{
+	int low = min;
+	int high = max;
+	int mid;
+	int ret;
+	unsigned long offset;
+	void *item;
+
+	while (low < high) {
+		mid = (low + high) / 2;
+		offset = mid * item_size;
+
+		item = ptr + offset;
+		ret = func(item, cmp_item);
+
+		if (ret < 0)
+			low = mid + 1;
+		else if (ret > 0)
+			high = mid;
+		else {
+			*slot = mid;
+			return 0;
+		}
+	}
+	*slot = low;
+	return 1;
+}
+
+/* XXX: these should go into the filesystem instance structure */
+static struct btrfs_chunk_map chunk_map;
+static struct btrfs_super_block sb;
+static u64 fs_tree;
+
+static int btrfs_comp_chunk_map(struct btrfs_chunk_map_item *m1,
+				struct btrfs_chunk_map_item *m2)
+{
+	if (__le64_to_cpu(m1->logical) > __le64_to_cpu(m2->logical))
+		return 1;
+	if (__le64_to_cpu(m1->logical) < __le64_to_cpu(m2->logical))
+		return -1;
+	return 0;
+}
+
+/* insert a new chunk mapping item */
+static void insert_map(struct btrfs_chunk_map_item *item)
+{
+	int ret;
+	int slot;
+	int i;
+
+	if (chunk_map.map == NULL) { /* first item */
+		chunk_map.map_length = BTRFS_MAX_CHUNK_ENTRIES;
+		chunk_map.map = (struct btrfs_chunk_map_item *)
+			malloc(chunk_map.map_length * sizeof(*chunk_map.map));
+		chunk_map.map[0] = *item;
+		chunk_map.cur_length = 1;
+		return;
+	}
+	ret = bin_search(chunk_map.map, sizeof(*item), item,
+			(cmp_func)btrfs_comp_chunk_map, 0,
+			chunk_map.cur_length, &slot);
+	if (ret == 0)/* already in map */
+		return;
+	if (chunk_map.cur_length == BTRFS_MAX_CHUNK_ENTRIES) {
+		/* should be impossible */
+		printf("too many chunk items\n");
+		return;
+	}
+	for (i = chunk_map.cur_length; i > slot; i--)
+		chunk_map.map[i] = chunk_map.map[i-1];
+	chunk_map.map[slot] = *item;
+	chunk_map.cur_length++;
+}
+
+/*
+ * from sys_chunk_array or chunk_tree, we can convert a logical address to
+ * a physical address we can not support multi device case yet
+ */
+static u64 logical_physical(u64 logical)
+{
+	struct btrfs_chunk_map_item item;
+	int slot, ret;
+
+	item.logical = logical;
+	ret = bin_search(chunk_map.map, sizeof(*chunk_map.map), &item,
+			(cmp_func)btrfs_comp_chunk_map, 0,
+			chunk_map.cur_length, &slot);
+	if (ret == 0)
+		slot++;
+	else if (slot == 0)
+		return -1;
+	if (logical >=
+		chunk_map.map[slot-1].logical + chunk_map.map[slot-1].length)
+		return -1;
+	return chunk_map.map[slot-1].physical + logical -
+			chunk_map.map[slot-1].logical;
+}
+
+int btrfs_devread(int sector, int byte_offset, int byte_len, char* buf)
+{
+    ALLOC_CACHE_ALIGN_BUFFER(char, sec_buf, SECTOR_SIZE);
+    unsigned block_len;
+   
+    /* Get the read to the beginning of a partition */
+    sector += byte_offset >> SECTOR_BITS;
+    byte_offset &= SECTOR_SIZE - 1;
+        
+    if (btrfs_block_dev_desc == NULL) {
+                printf("** Invalid Block Device Descriptor (NULL)\n");
+                return 0;
+    }
+    if (byte_offset != 0) {
+                /* read first part which isn't aligned with start of sector */
+                if (btrfs_block_dev_desc->
+                    block_read(btrfs_block_dev_desc->dev,
+                                part_info->start + sector, 1,
+                                (unsigned long *) sec_buf) != 1) {
+                        printf(" ** btrfs_devread() read error **\n");
+                        return 0;
+                }
+                memcpy(buf, sec_buf + byte_offset,
+                        min(SECTOR_SIZE - byte_offset, byte_len));
+                buf += min(SECTOR_SIZE - byte_offset, byte_len);
+                byte_len -= min(SECTOR_SIZE - byte_offset, byte_len);
+                sector++;
+     }
+       /* read sector aligned part */
+
+	block_len = byte_len & ~(SECTOR_SIZE - 1);
+
+        if (block_len == 0) {
+                ALLOC_CACHE_ALIGN_BUFFER(u8, p, SECTOR_SIZE);
+
+                block_len = SECTOR_SIZE;
+                btrfs_block_dev_desc->block_read(btrfs_block_dev_desc->dev,
+                                                  part_info->start + sector,
+                                                  1, (unsigned long *)p);
+                memcpy(buf, p, byte_len);
+                return 1;
+        }
+         ALLOC_CACHE_ALIGN_BUFFER(u8, t, block_len);
+         if (btrfs_block_dev_desc->block_read(btrfs_block_dev_desc->dev,
+                                               part_info->start + sector,
+                                               block_len / SECTOR_SIZE,
+                                               (unsigned long *) t) !=
+                                               block_len / SECTOR_SIZE) {
+                printf(" ** %s read error - block\n", __func__);
+                return 0;
+        }
+  
+        memcpy(buf, t, block_len);
+        block_len = byte_len & ~(SECTOR_SIZE - 1);
+        buf += block_len;
+        byte_len -= block_len;
+        sector += block_len / SECTOR_SIZE;
+        if (byte_len != 0) {
+                /* read rest of data which are not in whole sector */
+                if (btrfs_block_dev_desc->
+                    block_read(btrfs_block_dev_desc->dev,
+                                part_info->start + sector, 1,
+                                (unsigned long *) sec_buf) != 1) {
+                        printf("* %s read error - last part\n", __func__);
+                        return 0;
+                }
+                memcpy(buf, sec_buf, byte_len);
+        }
+
+     
+    return 1;  
+}
+/* btrfs has several super block mirrors, need to calculate their location */
+static inline u64 btrfs_sb_offset(int mirror)
+{
+	u64 start = 16 * 1024;
+	if (mirror)
+		return start << (BTRFS_SUPER_MIRROR_SHIFT * mirror);
+	return BTRFS_SUPER_INFO_OFFSET;
+}
+
+/* find the most recent super block */
+static int btrfs_read_super_block(struct fs_info *fs)
+{
+	int i;
+	int ret;
+	u8 fsid[BTRFS_FSID_SIZE];
+        u8 boots[512];
+	u64 offset;
+	u64 transid = 0;
+	struct btrfs_super_block buf;
+
+	sb.total_bytes = ~0;	/* Unknown as of yet */
+	
+	/*Only first header is checked for filesystem verification
+          mirror of this header can be used if required*/
+	offset = btrfs_sb_offset(0);
+
+	if ( btrfs_devread(128, 0, sizeof(struct btrfs_super_block), (char*)&buf)!=1)
+		return -1;
+
+                
+	if (buf.bytenr != offset ||
+	   strncmp((char *)(&buf.magic), BTRFS_MAGIC, sizeof(buf.magic)))
+        {
+	    return -1;
+        }
+                     
+	if (i == 0)
+		memcpy(fsid, buf.fsid, sizeof(fsid));
+	else if (memcmp(fsid, buf.fsid, sizeof(fsid)))
+		return -1;
+ 
+	if (buf.generation > transid) {
+		memcpy(&sb, &buf, sizeof(sb));
+		transid = buf.generation;
+	}
+	return 0;
+}
+
+static inline unsigned long btrfs_chunk_item_size(int num_stripes)
+{
+	return sizeof(struct btrfs_chunk) +
+		sizeof(struct btrfs_stripe) * (num_stripes - 1);
+}
+
+static void clear_path(struct btrfs_path *path)
+{
+	memset(path, 0, sizeof(*path));
+}
+
+static int btrfs_comp_keys(struct btrfs_disk_key *k1, struct btrfs_disk_key *k2)
+{
+	if (k1->objectid > k2->objectid)
+		return 1;
+	if (k1->objectid < k2->objectid)
+		return -1;
+	if (k1->type > k2->type)
+		return 1;
+	if (k1->type < k2->type)
+		return -1;
+	if (k1->offset > k2->offset)
+		return 1;
+	if (k1->offset < k2->offset)
+		return -1;
+	return 0;
+}
+
+/* compare keys but ignore offset, is useful to enumerate all same kind keys */
+static int btrfs_comp_keys_type(struct btrfs_disk_key *k1,
+					struct btrfs_disk_key *k2)
+{
+	if (k1->objectid > k2->objectid)
+		return 1;
+	if (k1->objectid < k2->objectid)
+		return -1;
+	if (k1->type > k2->type)
+		return 1;
+	if (k1->type < k2->type)
+		return -1;
+	return 0;
+}
+
+/* seach tree directly on disk ... */
+static int search_tree(struct fs_info *fs, u64 loffset,
+		struct btrfs_disk_key *key, struct btrfs_path *path)
+{
+	u8 buf[BTRFS_MAX_LEAF_SIZE];
+	struct btrfs_header *header = (struct btrfs_header *)buf;
+	struct btrfs_node *node = (struct btrfs_node *)buf;
+	struct btrfs_leaf *leaf = (struct btrfs_leaf *)buf;
+	int slot, ret;
+	u64 offset;
+
+	offset = logical_physical(loffset);
+         btrfs_devread(offset/SECTOR_SIZE, (offset%SECTOR_SIZE), sizeof(*header), (char*)header); 
+         if (header->level) {/*node*/
+                 btrfs_devread(((offset+sizeof(*header))/SECTOR_SIZE),((offset+sizeof(*header))%SECTOR_SIZE) , 	
+			__le32_to_cpu(sb.nodesize) - sizeof(*header),  (char *)&node->ptrs[0]); 
+		path->itemsnr[header->level] = header->nritems;
+		path->offsets[header->level] = loffset;
+		ret = bin_search(&node->ptrs[0], sizeof(struct btrfs_key_ptr),
+			key, (cmp_func)btrfs_comp_keys,
+			path->slots[header->level], header->nritems, &slot);
+		if (ret && slot > path->slots[header->level])
+			slot--;
+		path->slots[header->level] = slot;
+		ret = search_tree(fs, node->ptrs[slot].blockptr, key, path);
+	} else {/*leaf*/
+          
+                btrfs_devread(((offset+sizeof(*header))/SECTOR_SIZE), ((offset+sizeof(*header))%SECTOR_SIZE),
+			 (sb.leafsize) - sizeof(*header), (char *)&leaf->items);
+		path->itemsnr[header->level] = header->nritems;
+		path->offsets[0] = loffset;
+		ret = bin_search(&leaf->items[0], sizeof(struct btrfs_item),
+			key, (cmp_func)btrfs_comp_keys, path->slots[0],
+			header->nritems, &slot);
+		if (ret && slot > path->slots[header->level])
+			slot--;
+		path->slots[0] = slot;
+		path->item = leaf->items[slot];
+                btrfs_devread(((offset + sizeof(*header) + leaf->items[slot].offset)/SECTOR_SIZE), 
+                             ((offset + sizeof(*header) + leaf->items[slot].offset)%SECTOR_SIZE),
+                             leaf->items[slot].size, (char*)&path->data);
+	}
+	return ret;
+}
+
+/* return 0 if leaf found */
+static int next_leaf(struct fs_info *fs, struct btrfs_disk_key *key, struct btrfs_path *path)
+{
+	int slot;
+	int level = 1;
+
+	while (level < BTRFS_MAX_LEVEL) {
+		if (!path->itemsnr[level]) /* no more nodes */
+			return 1;
+		slot = path->slots[level] + 1;
+		if (slot >= path->itemsnr[level]) {
+			level++;
+			continue;;
+		}
+		path->slots[level] = slot;
+		path->slots[level-1] = 0; /* reset low level slots info */
+		search_tree(fs, path->offsets[level], key, path);
+		break;
+	}
+	if (level == BTRFS_MAX_LEVEL)
+		return 1;
+	return 0;
+}
+
+/* return 0 if slot found */
+static int next_slot(struct fs_info *fs, struct btrfs_disk_key *key, struct btrfs_path *path)
+{
+	int slot;
+
+	if (!path->itemsnr[0])
+		return 1;
+	slot = path->slots[0] + 1;
+	if (slot >= path->itemsnr[0])
+		return 1;
+	path->slots[0] = slot;
+	search_tree(fs, path->offsets[0], key, path);
+	return 0;
+}
+
+/*
+ * read chunk_array in super block
+ */
+static void btrfs_read_sys_chunk_array(void)
+{
+	struct btrfs_chunk_map_item item;
+	struct btrfs_disk_key *key;
+	struct btrfs_chunk *chunk;
+	int cur;
+
+	/* read chunk array in superblock */
+	cur = 0;
+        
+	while (cur < __le32_to_cpu(sb.sys_chunk_array_size)) {
+		key = (struct btrfs_disk_key *)(sb.sys_chunk_array + cur);
+		cur += sizeof(*key);
+		chunk = (struct btrfs_chunk *)(sb.sys_chunk_array + cur);
+		cur += btrfs_chunk_item_size(chunk->num_stripes);
+		/* insert to mapping table, ignore multi stripes */
+		item.logical = key->offset;
+		item.length = chunk->length;
+		item.devid = chunk->stripe.devid;
+		item.physical = chunk->stripe.offset;/*ignore other stripes */
+                          
+                  
+		insert_map(&item);
+	}
+}
+
+/* read chunk items from chunk_tree and insert them to chunk map */
+static void btrfs_read_chunk_tree(struct fs_info *fs)
+{
+	struct btrfs_disk_key search_key;
+	struct btrfs_chunk *chunk;
+	struct btrfs_chunk_map_item item;
+	struct btrfs_path path;
+        int status;
+
+	if (!(__le64_to_cpu(sb.flags) & BTRFS_SUPER_FLAG_METADUMP)) {
+		if (__le64_to_cpu(sb.num_devices) > 1)
+                {
+			printf("warning: only support one btrfs device %d\n",
+ 				__le64_to_cpu(sb.num_devices));
+ 			return;
+                }
+		/* read chunk from chunk_tree */
+		search_key.objectid = BTRFS_FIRST_CHUNK_TREE_OBJECTID;
+		search_key.type = BTRFS_CHUNK_ITEM_KEY;
+		search_key.offset = 0;
+		clear_path(&path);
+		search_tree(fs, (sb.chunk_root), &search_key, &path);
+		do {
+			do {
+                                 
+				if (status=btrfs_comp_keys_type(&search_key,
+							&path.item.key))
+					break;
+				chunk = (struct btrfs_chunk *)(path.data);
+				/* insert to mapping table, ignore stripes */
+				item.logical = path.item.key.offset;
+				item.length = chunk->length;
+				item.devid = chunk->stripe.devid;
+				item.physical = chunk->stripe.offset;
+				insert_map(&item);
+			} while (!next_slot(fs, &search_key, &path));
+			if (btrfs_comp_keys_type(&search_key, &path.item.key))
+				break;
+		} while (!next_leaf(fs, &search_key, &path));
+	}
+}
+
+static inline u64 btrfs_name_hash(const char *name, int len)
+{
+	return btrfs_crc32c((u32)~1, name, len);
+}
+
+static struct inode *btrfs_iget_by_inr(struct fs_info *fs, u64 inr)
+{
+	struct inode *inode;
+	struct btrfs_inode_item inode_item;
+	struct btrfs_disk_key search_key;
+	struct btrfs_path path;
+	int ret;
+
+	/* FIXME: some BTRFS inode member are u64, while our logical inode
+           is u32, we may need change them to u64 later */
+	search_key.objectid = inr;
+	search_key.type = BTRFS_INODE_ITEM_KEY;
+	search_key.offset = 0;
+	clear_path(&path);
+	ret = search_tree(fs, fs_tree, &search_key, &path);
+	if (ret)
+        {
+	    printf("%s search_tree failed\n", __func__);     
+            return NULL;
+        }
+
+	inode_item = *(struct btrfs_inode_item *)path.data;
+	if (!(inode = alloc_inode(fs, inr, sizeof(struct btrfs_pvt_inode))))
+        {
+		printf("%s alloc_inode failed\n", __func__);
+        	return NULL;
+	}
+	inode->ino = inr;
+	inode->size = inode_item.size;
+	inode->mode = IFTODT(inode_item.mode);
+	if (inode->mode == DT_REG || inode->mode == DT_LNK) {
+		struct btrfs_file_extent_item extent_item;
+		u64 offset;
+
+		/* get file_extent_item */
+		search_key.type = BTRFS_EXTENT_DATA_KEY;
+		search_key.offset = 0;
+		clear_path(&path);
+		ret = search_tree(fs, fs_tree, &search_key, &path);
+		if (ret)
+			return NULL; /* impossible */
+		extent_item = *(struct btrfs_file_extent_item *)path.data;
+		if (extent_item.type == BTRFS_FILE_EXTENT_INLINE)/* inline file */
+			offset = path.offsets[0] + sizeof(struct btrfs_header)
+				+ path.item.offset
+				+ offsetof(struct btrfs_file_extent_item, disk_bytenr);
+		else
+			offset = extent_item.disk_bytenr;
+		PVT(inode)->offset = offset;
+	}
+	return inode;
+}
+
+static struct inode *btrfs_iget_root(struct fs_info *fs)
+{
+	/* BTRFS_FIRST_CHUNK_TREE_OBJECTID(256) actually is first OBJECTID for FS_TREE */
+	return btrfs_iget_by_inr(fs, BTRFS_FIRST_CHUNK_TREE_OBJECTID);
+}
+
+static struct inode *btrfs_iget(const char *name, struct inode *parent)
+{
+	struct fs_info *fs = parent->fs;
+	struct btrfs_disk_key search_key;
+	struct btrfs_path path;
+	struct btrfs_dir_item dir_item;
+	int ret;
+
+	search_key.objectid = parent->ino;
+	search_key.type = BTRFS_DIR_ITEM_KEY;
+	search_key.offset = btrfs_name_hash(name, strlen(name));
+	clear_path(&path);
+	ret = search_tree(fs, fs_tree, &search_key, &path);
+	if (ret)
+		return NULL;
+	dir_item = *(struct btrfs_dir_item *)path.data;
+
+	return btrfs_iget_by_inr(fs, dir_item.location.objectid);
+}
+
+static int btrfs_readlink(struct inode *inode, char *buf)
+{
+         btrfs_devread((logical_physical(PVT(inode)->offset)/SECTOR_SIZE), 
+            (logical_physical(PVT(inode)->offset)%SECTOR_SIZE), inode->size, (char*)buf);
+	    buf[inode->size] = '\0';
+	return inode->size;
+}
+
+static int btrfs_readdir(struct file *file, struct dirent *dirent)
+{
+	struct fs_info *fs = file->fs;
+	struct inode *inode = file->inode;
+	struct btrfs_disk_key search_key;
+	struct btrfs_path path;
+	struct btrfs_dir_item *dir_item;
+	int ret;
+
+	/*
+	 * we use file->offset to store last search key.offset, will will search
+	 * key that lower that offset, 0 means first search and we will search
+         * -1UL, which is the biggest possible key
+         */
+	search_key.objectid = inode->ino;
+	search_key.type = BTRFS_DIR_ITEM_KEY;
+	search_key.offset = file->offset - 1;
+	clear_path(&path);
+	ret = search_tree(fs, fs_tree, &search_key, &path);
+
+	if (ret) {
+		if (btrfs_comp_keys_type(&search_key, &path.item.key))
+			return -1;
+	}
+
+	dir_item = (struct btrfs_dir_item *)path.data;
+	file->offset = path.item.key.offset;
+	dirent->d_ino = dir_item->location.objectid;
+	dirent->d_off = file->offset;
+	dirent->d_reclen = offsetof(struct dirent, d_name)
+		+ dir_item->name_len + 1;
+	dirent->d_type = IFTODT(dir_item->type);
+	memcpy(dirent->d_name, dir_item + 1, dir_item->name_len);
+	dirent->d_name[dir_item->name_len] = '\0';
+
+	return 0;
+}
+
+static int btrfs_next_extent(struct inode *inode, uint32_t lstart)
+{
+	struct btrfs_disk_key search_key;
+	struct btrfs_file_extent_item extent_item;
+	struct btrfs_path path;
+	int ret;
+	u64 offset;
+	struct fs_info *fs = inode->fs;
+	u32 sec_shift = SECTOR_BITS;
+	u32 sec_size = SECTOR_SIZE;
+
+	search_key.objectid = inode->ino;
+	search_key.type = BTRFS_EXTENT_DATA_KEY;
+	search_key.offset = lstart << sec_shift;
+	clear_path(&path);
+	ret = search_tree(fs, fs_tree, &search_key, &path);
+	if (ret) { /* impossible */
+		printf("btrfs: search extent data error\n");
+		return -1;
+	}
+	extent_item = *(struct btrfs_file_extent_item *)path.data;
+
+	if (extent_item.encryption) {
+	    printf("btrfs: found encrypted data, cannot continue\n");
+	    return -1;
+	}
+	if (extent_item.compression) {
+	    printf("btrfs: found compressed data, cannot continue\n");
+	    return -1;
+	}
+
+	if (extent_item.type == BTRFS_FILE_EXTENT_INLINE) {/* inline file */
+		/* we fake a extent here, and PVT of inode will tell us */
+		offset = path.offsets[0] + sizeof(struct btrfs_header)
+			+ path.item.offset
+			+ offsetof(struct btrfs_file_extent_item, disk_bytenr);
+		inode->next_extent.len =
+			(inode->size + sec_size -1) >> sec_shift;
+	} else {
+		offset = extent_item.disk_bytenr + extent_item.offset;
+		inode->next_extent.len =
+			(extent_item.num_bytes + sec_size - 1) >> sec_shift;
+	}
+	inode->next_extent.pstart =
+		logical_physical(offset) >> sec_shift;
+	PVT(inode)->offset = offset;
+	return 0;
+}
+
+static uint32_t btrfs_getfssec(struct file *file, char *buf, int sectors,
+					char *have_more)
+{
+	u32 ret;
+	struct fs_info *fs = file->fs;
+	u32 off = PVT(file->inode)->offset % SECTOR_SIZE;
+	char handle_inline = 0;
+
+	if (off && !file->offset) {/* inline file first read patch */
+		file->inode->size += off;
+		handle_inline = 1;
+	}
+	ret = generic_getfssec(file, buf, sectors, have_more);
+	if (!ret)
+		return ret;
+	off = PVT(file->inode)->offset % SECTOR_SIZE;
+	if (handle_inline) {/* inline file patch */
+		ret -= off;
+		memcpy(buf, buf + off, ret);
+	}
+	return ret;
+}
+
+static void btrfs_get_fs_tree(struct fs_info *fs)
+{
+	struct btrfs_disk_key search_key;
+	struct btrfs_path path;
+	struct btrfs_root_item *tree;
+	char subvol_ok = 0;
+
+	/* check if subvol is filled by installer */
+        if (*subvolname) {
+		search_key.objectid = BTRFS_FS_TREE_OBJECTID;
+		search_key.type = BTRFS_ROOT_REF_KEY;
+		search_key.offset = 0;
+		clear_path(&path);
+		if (search_tree(fs, __le64_to_cpu(sb.root), &search_key, &path))
+			next_slot(fs, &search_key, &path);
+		do {
+			do {
+				struct btrfs_root_ref *ref;
+				int pathlen, status;
+
+				if (status=btrfs_comp_keys_type(&search_key,
+							&path.item.key))
+					break;
+				ref = (struct btrfs_root_ref *)path.data;
+				pathlen = path.item.size - sizeof(struct btrfs_root_ref);
+                                printf("sub_vol found %s\n", (char*)(ref+1));
+				if (!strncmp((char*)(ref + 1), subvolname, pathlen)) {
+					subvol_ok = 1;
+					break;
+				}
+			} while (!next_slot(fs, &search_key, &path));
+			if (subvol_ok)
+				break;
+			if (btrfs_comp_keys_type(&search_key, &path.item.key))
+				break;
+		} while (!next_leaf(fs, &search_key, &path));
+		if (!subvol_ok) /* should be impossible */
+			printf("no subvol found\n");
+	}
+	/* find fs_tree from tree_root */
+	if (subvol_ok)
+		search_key.objectid = path.item.key.offset;
+	else /* "default" volume */
+		search_key.objectid = BTRFS_FS_TREE_OBJECTID;
+	search_key.type = BTRFS_ROOT_ITEM_KEY;
+	search_key.offset =-1;
+	clear_path(&path);
+	search_tree(fs, (sb.root), &search_key, &path);
+	tree = (struct btrfs_root_item *)path.data;
+	fs_tree = tree->bytenr;
+}
+
+/* init. the fs meta data, return the block size shift bits. */
+int btrfs_fs_init(struct fs_info *fs)
+{
+    
+	btrfs_init_crc32c();
+	btrfs_read_super_block(fs);
+	if (strncmp((char *)(&sb.magic), BTRFS_MAGIC, sizeof(sb.magic)))
+		return -1;
+
+	btrfs_read_sys_chunk_array();
+	btrfs_read_chunk_tree(fs);
+	btrfs_get_fs_tree(fs);
+        fs->root = btrfs_iget_root(fs);
+        parent_inode=*(fs->root);
+
+	return 1;
+}
+static inline uint16_t file_to_handle(struct file *file)
+{
+    return file ? (file - files)+1 : 0;
+}
+
+static inline struct file *handle_to_file(uint16_t handle)
+{
+    return handle ? &files[handle-1] : NULL;
+}
+
+/*
+ * Free a refcounted inode
+ */
+void put_inode(struct inode *inode)
+{
+    while (inode && --inode->refcnt == 0) {
+        struct inode *dead = inode;
+        inode = inode->parent;
+        if (dead->name)
+            free((char *)dead->name);
+        free(dead);
+    }
+}
+
+/*
+ * Get a new inode structure
+ */
+struct inode *alloc_inode(struct fs_info *fs, uint32_t ino, size_t data)
+{
+    struct inode *inode = malloc(sizeof(struct inode) + data);
+    if (inode) {
+        inode->fs = fs;
+        inode->ino = ino;
+        inode->refcnt = 1;
+    }
+    return inode;
+}
+
+/*
+ * Get an empty file structure
+ */
+static struct file *alloc_file(void)
+{
+    int i;
+    struct file *file = files;
+
+    for (i = 0; i < MAX_OPEN; i++) {
+        if (!file->fs)
+            return file;
+        file++;
+    }
+
+    return NULL;
+}
+
+/*
+ * Close and free a file structure
+ */
+static inline void free_file(struct file *file)
+{
+    memset(file, 0, sizeof *file);
+}
+
+void generic_close_file(struct file *file)
+{
+    if (file->inode) {
+        file->offset = 0;
+        put_inode(file->inode);
+    }
+}
+
+void _close_file(struct file *file)
+{
+    if (file->fs)
+        generic_close_file(file);
+    free_file(file);
+}
+
+void btrfs_mangle_name(char *dst, const char *src)
+{
+    char *p = dst;
+    int i = FILENAME_MAX-1;
+
+    while (not_whitespace(*src)) {
+        if (*src == '/') {
+            if (src[1] == '/') {
+                src++;
+                i--;
+                continue;
+            }
+        }
+        i--;
+        *dst++ = *src++;
+    }
+    while (1) {
+        if (dst == p)
+            break;
+        if (dst[-1] != '/')
+            break;
+        if ((dst[-1] == '/') && ((dst - 1) == p))
+            break;
+
+        dst--;
+        i++;
+    }
+
+    i++;
+    for (; i > 0; i --)
+        *dst++ = '\0';
+
+}
+int btrfs_open_file(const char *name, struct com32_filedata *filedata)
+{
+    int rv;
+    struct file *file;
+    char mangled_name[FILENAME_MAX];
+
+    btrfs_mangle_name(mangled_name, name);
+    rv = searchdir(mangled_name);
+    if (rv < 0)
+        return rv;
+
+    file = handle_to_file(rv);
+    filedata->size      = file->inode->size;
+    filedata->handle    = rv;
+    return rv;
+}
+
+int searchdir(const char *name)
+{
+    struct inode *inode = NULL;
+    struct inode *parent = &parent_inode;
+    struct file *file;
+    char *pathbuf = NULL;
+    char *part, *p, echar;
+    int symlink_count = MAX_SYMLINK_CNT;
+    
+    if (!(file = alloc_file()))
+        goto err_no_close;
+
+    p = pathbuf = strdup(name);
+    if (!pathbuf)
+        goto err;
+
+    do {
+    got_link:
+        if (*p == '/') {
+            put_inode(parent);
+            parent =  &parent_inode;// get_inode(this_fs->root);
+        }
+
+        do {
+            inode = get_inode(parent);
+
+            while (*p == '/')
+                p++;
+
+            if (!*p)
+                break;
+
+            part = p;
+            while ((echar = *p) && echar != '/')
+                p++;
+            *p++ = '\0';
+            if (part[0] == '.' && part[1] == '.' && part[2] == '\0') {
+	       if (inode->parent) {
+                    put_inode(parent);
+                    parent = get_inode(inode->parent);
+                    put_inode(inode);
+                    inode = NULL;
+                    if (!echar) {
+                        /* Terminal double dots */
+                        inode = parent;
+                        parent = inode->parent ?
+                            get_inode(inode->parent) : NULL;
+                    }
+                }
+            } else if (part[0] != '.' || part[1] != '\0') {
+                inode = btrfs_iget(part, parent);
+                if (!inode)
+                    goto err;
+                if (inode->mode == DT_LNK) {
+                    char *linkbuf, *q;
+                    int name_len = echar ? strlen(p) : 0;
+                    int total_len = inode->size + name_len + 2;
+                    int link_len;
+		    
+                    if (/*!this_fs->fs_ops->readlink ||*/
+                        --symlink_count == 0       ||      /* limit check */
+                        total_len > MAX_SYMLINK_BUF)
+                        goto err;
+
+                    linkbuf = malloc(total_len);
+                    if (!linkbuf)
+                        goto err;
+
+                    link_len = btrfs_readlink(inode, linkbuf);
+                    if (link_len <= 0) {
+                        free(linkbuf);
+                        goto err;
+                    }
+
+                    q = linkbuf + link_len;
+
+                    if (echar) {
+                        if (link_len > 0 && q[-1] != '/')
+                            *q++ = '/';
+
+                        memcpy(q, p, name_len+1);
+                    } else {
+                        *q = '\0';
+                    }
+
+                    free(pathbuf);
+                    p = pathbuf = linkbuf;
+                    put_inode(inode);
+                    inode = NULL;
+                    goto got_link;
+                }
+
+                inode->name = strdup(part);
+
+                inode->parent = parent;
+                parent = NULL;
+
+                if (!echar)
+                    break;
+
+                if (inode->mode != DT_DIR)
+                    goto err;
+
+                parent = inode;
+                inode = NULL;
+            }
+        } while (echar);
+    } while (0);
+
+    free(pathbuf);
+    pathbuf = NULL;
+    put_inode(parent);
+    parent = NULL;
+
+    if (!inode)
+        goto err;
+
+    file->inode  = inode;
+    file->offset = 0;
+    return file_to_handle(file);
+
+err:
+    put_inode(inode);
+    put_inode(parent);
+    if (pathbuf)
+        free(pathbuf);
+    _close_file(file);
+err_no_close:
+    return -1;
+}
+
+static void get_next_extent(struct inode *inode)
+{
+    /* The logical start address that we care about... */
+    uint32_t lstart = inode->this_extent.lstart + inode->this_extent.len;
+
+    if (btrfs_next_extent(inode, lstart))
+        inode->next_extent.len = 0; /* ERROR */
+    inode->next_extent.lstart = lstart;
+}
+
+int getfssec(struct com32_filedata *filedata, char * buf)
+{
+    int sectors;
+    char have_more;
+    uint32_t bytes_read;
+    struct file *file;
+    uint16_t handle;
+    if(filedata->size>=512)
+    {
+       sectors = filedata->size/SECTOR_SIZE;
+       sectors += (filedata->size%SECTOR_SIZE)?1:0;
+    }
+    else sectors=2;
+
+    file = handle_to_file(filedata->handle);
+
+    bytes_read = btrfs_getfssec(file, buf, sectors, &have_more);
+    if (!have_more) {
+    }
+    return bytes_read;
+}
+
+uint32_t generic_getfssec(struct file *file, char *buf,
+                          int sectors, char *have_more)
+{
+    struct inode *inode = file->inode;
+    struct fs_info *fs = file->fs;
+    uint32_t bytes_read = 0;
+    uint32_t bytes_left = inode->size - file->offset;
+    uint32_t sectors_left =
+        (bytes_left + SECTOR_SIZE - 1) >> 9;
+    uint32_t lsector;
+
+    if (sectors > sectors_left)
+        sectors = sectors_left;
+
+    if (!sectors)
+        return 0;
+
+    lsector = file->offset >> 9;
+
+    if (lsector < inode->this_extent.lstart ||
+        lsector >= inode->this_extent.lstart + inode->this_extent.len) {
+        /* inode->this_extent unusable, maybe next_extent is... */
+        inode->this_extent = inode->next_extent;
+    }
+
+    if (lsector < inode->this_extent.lstart ||
+        lsector >= inode->this_extent.lstart + inode->this_extent.len) {
+        /* Still nothing useful... */
+        inode->this_extent.lstart = lsector;
+        inode->this_extent.len = 0;
+    } else {
+        /* We have some usable information */
+        uint32_t delta = lsector - inode->this_extent.lstart;
+        inode->this_extent.lstart = lsector;
+        inode->this_extent.len -= delta;
+    inode->this_extent.pstart
+            = next_psector(inode->this_extent.pstart, delta);
+    }
+
+
+    while (sectors) {
+        uint32_t chunk;
+        size_t len;
+
+        while (sectors > inode->this_extent.len) {
+            if (!inode->next_extent.len ||
+                inode->next_extent.lstart !=
+                inode->this_extent.lstart + inode->this_extent.len)
+                get_next_extent(inode);
+               if (!inode->this_extent.len) {
+                /* Doesn't matter if it's contiguous... */
+                inode->this_extent = inode->next_extent;
+                if (!inode->next_extent.len) {
+                    sectors = 0; /* Failed to get anything... we're dead */
+                    break;
+                }
+            } else if (inode->next_extent.len &&
+                inode->next_extent.pstart == next_pstart(&inode->this_extent)) {
+                /* Coalesce extents and loop */
+                inode->this_extent.len += inode->next_extent.len;
+            } else {
+                /* Discontiguous extents */
+                break;
+            }
+        }
+        
+
+        chunk = min(sectors, inode->this_extent.len);
+        len = chunk << 9;//SECTOR_SHIFT(fs);
+
+
+        if (inode->this_extent.pstart == EXTENT_ZERO) {
+            memset(buf, 0, len);
+        } else {
+            btrfs_block_dev_desc->block_read( btrfs_block_dev_desc->dev,
+             part_info->start+(inode->this_extent.pstart), chunk, buf);
+            inode->this_extent.pstart += chunk;
+        }
+        
+         buf += len;
+        sectors -= chunk;
+        bytes_read += len;
+        inode->this_extent.lstart += chunk;
+        inode->this_extent.len -= chunk;
+    }
+
+    bytes_read = min(bytes_read, bytes_left);
+    file->offset += bytes_read;
+
+    if (have_more)
+        *have_more = bytes_read < bytes_left;
+
+    return bytes_read;
+}
diff --git a/fs/fs.c b/fs/fs.c
index 023e7ef..b662a25 100644
--- a/fs/fs.c
+++ b/fs/fs.c
@@ -20,9 +20,8 @@ 
 #include <ext4fs.h>
 #include <fat.h>
 #include <fs.h>
-
+#include <btrfs.h>
 DECLARE_GLOBAL_DATA_PTR;
-
 static block_dev_desc_t *fs_dev_desc;
 static disk_partition_t fs_partition;
 static int fs_type = FS_TYPE_ANY;
@@ -79,6 +78,73 @@  static inline void fs_close_fat(void)
 #define fs_read_fat fs_read_unsupported
 #endif
 
+
+#ifdef CONFIG_FS_BTR
+struct fs_info fs;
+static int fs_probe_btr(void)
+{
+       
+        btrfs_set_blk_dev(fs_dev_desc, &fs_partition);
+
+        if (btrfs_fs_init(&fs)==-1) {
+                printf("btrfs probe failed\n");
+                return -1;
+        }
+
+        return 0;
+}
+
+static void fs_close_btr(void)
+{
+}
+
+#define fs_ls_btr btrfs_ls
+static int fs_read_btr(const char *filename, ulong addr, int offset, int len)
+{
+        int file_len=0;
+        int len_read;
+        struct com32_filedata filedata;
+        int handle;
+        if (offset != 0) {
+                printf("** Cannot support non-zero offset **\n");
+                return -1;
+        }
+
+        handle=btrfs_open_file(filename, &filedata);
+        if (handle < 0) {
+                printf("** File not found %s Invalid handle**\n", filename);
+                return -1;
+        }
+        //file handle is valid get the size of the file
+        len=filedata.size;
+        if (len == 0)
+                len = file_len;
+
+        len_read = getfssec(&filedata, (char *)addr);
+        if (len_read != len) {
+                printf("** Unable to read file %s **\n", filename);
+                return -1;
+        }
+
+        return len_read;
+}
+
+#else
+static inline int fs_probe_btr(void)
+{
+        return -1;
+}
+
+static inline void fs_close_btr(void)
+{
+}
+
+#define fs_ls_btr fs_ls_unsupported
+#define fs_read_btr fs_read_unsupported
+#endif
+
+
+
 #ifdef CONFIG_FS_EXT4
 static int fs_probe_ext(void)
 {
@@ -155,6 +221,10 @@  static struct {
 		.fstype = FS_TYPE_EXT,
 		.probe = fs_probe_ext,
 	},
+        {
+		.fstype = FS_TYPE_BTR,
+		.probe = fs_probe_btr,
+        },
 };
 
 int fs_set_blk_dev(const char *ifname, const char *dev_part_str, int fstype)
@@ -178,7 +248,6 @@  int fs_set_blk_dev(const char *ifname, const char *dev_part_str, int fstype)
 	for (i = 0; i < ARRAY_SIZE(fstypes); i++) {
 		if ((fstype != FS_TYPE_ANY) && (fstype != fstypes[i].fstype))
 			continue;
-
 		if (!fstypes[i].probe()) {
 			fs_type = fstypes[i].fstype;
 			return 0;
@@ -198,6 +267,9 @@  static void fs_close(void)
 	case FS_TYPE_EXT:
 		fs_close_ext();
 		break;
+        case FS_TYPE_BTR:
+		fs_close_btr();
+		break;
 	default:
 		break;
 	}
@@ -208,7 +280,6 @@  static void fs_close(void)
 int fs_ls(const char *dirname)
 {
 	int ret;
-
 	switch (fs_type) {
 	case FS_TYPE_FAT:
 		ret = fs_ls_fat(dirname);
@@ -216,6 +287,9 @@  int fs_ls(const char *dirname)
 	case FS_TYPE_EXT:
 		ret = fs_ls_ext(dirname);
 		break;
+        case FS_TYPE_BTR:
+		ret = fs_ls_unsupported(dirname);
+		break;
 	default:
 		ret = fs_ls_unsupported(dirname);
 		break;
@@ -237,11 +311,13 @@  int fs_read(const char *filename, ulong addr, int offset, int len)
 	case FS_TYPE_EXT:
 		ret = fs_read_ext(filename, addr, offset, len);
 		break;
+        case FS_TYPE_BTR:
+		ret = fs_read_btr(filename, addr, offset, len);
+		break; 
 	default:
 		ret = fs_read_unsupported(filename, addr, offset, len);
 		break;
 	}
-
 	fs_close();
 
 	return ret;
diff --git a/include/btrfs.h b/include/btrfs.h
new file mode 100644
index 0000000..4124ca6
--- /dev/null
+++ b/include/btrfs.h
@@ -0,0 +1,398 @@ 
+#ifndef _BTRFS_H_
+#define _BTRFS_H_
+
+#include <asm/byteorder.h>
+/* type that store on disk, but it is same as cpu type for i386 arch */
+
+#define CURRENTDIR_MAX 15
+#define MAX_OPEN 5
+#define FILENAME_MAX  20
+#define MAX_SYMLINK_CNT    20
+#define MAX_SYMLINK_BUF 4096
+#define SECTOR_SHIFT(fs) ((fs)->sector_shift)
+#define IFTODT(mode) (((mode) & 0170000) >> 12)
+#define SECTOR_SIZE                0x200
+#define SECTOR_BITS             9
+#define EXTENT_ZERO     ((__le32)-1) /* All-zero extent */
+#define EXTENT_VOID     ((__le32)-2) /* Invalid information */
+#define DT_LNK			10
+#define DT_REG			8
+#define DT_DIR			4
+
+
+#define EXTENT_SPECIAL(x)       ((x) >= EXTENT_VOID)
+#define MAX_SUBVOL_NAME         50
+struct com32_filedata {
+    size_t size;                /* File size */
+    int blocklg2;               /* log2(block size) */
+    uint16_t handle;            /* File handle */
+};
+
+struct fs_info {
+    const struct fs_ops *fs_ops;
+    struct device *fs_dev;
+    void *fs_info;             /* The fs-specific information */
+    int sector_shift, sector_size;
+    int block_shift, block_size;
+    struct inode *root, *cwd;           /* Root and current directories */
+    char cwd_name[CURRENTDIR_MAX];      /* Current directory by name */
+};
+/*
+ * Extent structure: contains the mapping of some chunk of a file
+ * that is contiguous on disk.
+ */
+struct extent {
+    //sector_t    pstart;         /* Physical start sector */
+    __le64   pstart;
+    __le32    lstart;         /* Logical start sector */
+    __le32    len;            /* Number of contiguous sectors */
+}__attribute__ ((__packed__));
+
+
+struct inode {
+    struct fs_info *fs;  /* The filesystem this inode is associated with */
+    struct inode *parent;       /* Parent directory, if any */
+    const u8 *name;           /* Name, valid for generic path search only */
+    __le32          refcnt;
+    __le32       mode;   /* FILE , DIR or SYMLINK */
+    __le32     size;
+    __le32     blocks; /* How many blocks the file take */
+    __le32     ino;    /* Inode number */
+    __le32     atime;  /* Access time */
+    __le32     mtime;  /* Modify time */
+    __le32     ctime;  /* Create time */
+    __le32     dtime;  /* Delete time */
+    __le32     flags;
+    __le32     file_acl;
+    struct extent this_extent, next_extent;
+    u8         pvt[0]; /* Private filesystem data */
+}__attribute__ ((__packed__));
+struct file {
+    struct fs_info *fs;
+    __le64 offset;            /* for next read */
+    struct inode *inode;        /* The file-specific information */
+}__attribute__ ((__packed__));
+
+#define NAME_MAX 20
+struct dirent {
+    uint32_t d_ino;
+    uint32_t d_off;
+    uint16_t d_reclen;
+    uint16_t d_type;
+    char d_name[NAME_MAX + 1];
+};
+  
+
+#include "crc32c.h"
+#define btrfs_crc32c crc32c_le
+
+#define BTRFS_SUPER_INFO_OFFSET (64 * 1024)
+#define BTRFS_SUPER_INFO_SIZE 4096
+#define BTRFS_MAX_LEAF_SIZE 4096
+#define BTRFS_BLOCK_SHIFT 12
+
+#define BTRFS_SUPER_MIRROR_MAX   3
+#define BTRFS_SUPER_MIRROR_SHIFT 12
+#define BTRFS_CSUM_SIZE 32
+#define BTRFS_FSID_SIZE 16
+#define BTRFS_LABEL_SIZE 256
+#define BTRFS_SYSTEM_CHUNK_ARRAY_SIZE 2048
+#define BTRFS_UUID_SIZE 16
+
+#define BTRFS_MAGIC "_BHRfS_M"
+
+#define BTRFS_SUPER_FLAG_METADUMP	(1ULL << 33)
+
+#define BTRFS_DEV_ITEM_KEY	216
+#define BTRFS_CHUNK_ITEM_KEY	228
+#define BTRFS_ROOT_REF_KEY	156
+#define BTRFS_ROOT_ITEM_KEY	132
+#define BTRFS_EXTENT_DATA_KEY	108
+#define BTRFS_DIR_ITEM_KEY	84
+#define BTRFS_INODE_ITEM_KEY	1
+
+#define BTRFS_EXTENT_TREE_OBJECTID 2ULL
+#define BTRFS_FS_TREE_OBJECTID 5ULL
+
+#define BTRFS_FIRST_CHUNK_TREE_OBJECTID 256ULL
+
+#define BTRFS_FILE_EXTENT_INLINE 0
+#define BTRFS_FILE_EXTENT_REG 1
+#define BTRFS_FILE_EXTENT_PREALLOC 2
+
+#define BTRFS_MAX_LEVEL 8
+#define BTRFS_MAX_CHUNK_ENTRIES 256
+
+#define BTRFS_FT_REG_FILE	1
+#define BTRFS_FT_DIR		2
+#define BTRFS_FT_SYMLINK	7
+
+#define ROOT_DIR_WORD 0x002f
+
+struct btrfs_dev_item {
+	__le64 devid;
+	__le64 total_bytes;
+	__le64 bytes_used;
+	__le32 io_align;
+	__le32 io_width;
+	__le32 sector_size;
+	__le64 type;
+	__le64 generation;
+	__le64 start_offset;
+	__le32 dev_group;
+	u8 seek_speed;
+	u8 bandwidth;
+	u8 uuid[BTRFS_UUID_SIZE];
+	u8 fsid[BTRFS_UUID_SIZE];
+} __attribute__ ((__packed__));
+
+struct btrfs_super_block {
+        u8 csum[BTRFS_CSUM_SIZE];
+        /* the first 4 fields must match struct btrfs_header */
+        u8 fsid[BTRFS_FSID_SIZE];    /* FS specific uuid */
+        __le64 bytenr; /* this block number */
+        __le64 flags;
+
+        /* allowed to be different from the btrfs_header from here own down */
+        __le64 magic;
+        __le64 generation;
+        __le64 root;
+        __le64 chunk_root;
+        __le64 log_root;
+
+        /* this will help find the new super based on the log root */
+        __le64 log_root_transid;
+        __le64 total_bytes;
+        __le64 bytes_used;
+        __le64 root_dir_objectid;
+        __le64 num_devices;
+        __le32 sectorsize;
+        __le32 nodesize;
+        __le32 leafsize;
+        __le32 stripesize;
+        __le32 sys_chunk_array_size;
+        __le64 chunk_root_generation;
+        __le64 compat_flags;
+        __le64 compat_ro_flags;
+        __le64 incompat_flags;
+        __le16 csum_type;
+        u8 root_level;
+        u8 chunk_root_level;
+        u8 log_root_level;
+        struct btrfs_dev_item dev_item;
+
+        char label[BTRFS_LABEL_SIZE];
+
+        __le64 cache_generation;
+
+        /* future expansion */
+        __le64 reserved[31];
+        u8 sys_chunk_array[BTRFS_SYSTEM_CHUNK_ARRAY_SIZE];
+} __attribute__ ((__packed__));
+struct btrfs_disk_key {
+	__le64 objectid;
+	u8 type;
+	__le64 offset;
+} __attribute__ ((__packed__));
+
+struct btrfs_stripe {
+	__le64 devid;
+	__le64 offset;
+	u8 dev_uuid[BTRFS_UUID_SIZE];
+} __attribute__ ((__packed__));
+
+struct btrfs_chunk {
+	__le64 length;
+	__le64 owner;
+	__le64 stripe_len;
+	__le64 type;
+	__le32 io_align;
+	__le32 io_width;
+	__le32 sector_size;
+	__le16 num_stripes;
+	__le16 sub_stripes;
+	struct btrfs_stripe stripe;
+} __attribute__ ((__packed__));
+
+struct btrfs_header {
+	/* these first four must match the super block */
+	u8 csum[BTRFS_CSUM_SIZE];
+	u8 fsid[BTRFS_FSID_SIZE]; /* FS specific uuid */
+	__le64 bytenr; /* which block this node is supposed to live in */
+	__le64 flags;
+
+	/* allowed to be different from the super from here on down */
+	u8 chunk_tree_uuid[BTRFS_UUID_SIZE];
+	__le64 generation;
+	__le64 owner;
+	__le32 nritems;
+	u8 level;
+} __attribute__ ((__packed__));
+
+struct btrfs_item {
+	struct btrfs_disk_key key;
+	__le32 offset;
+	__le32 size;
+} __attribute__ ((__packed__));
+
+struct btrfs_leaf {
+	struct btrfs_header header;
+	struct btrfs_item items[];
+} __attribute__ ((__packed__));
+
+struct btrfs_key_ptr {
+	struct btrfs_disk_key key;
+	__le64 blockptr;
+	__le64 generation;
+} __attribute__ ((__packed__));
+
+struct btrfs_node {
+	struct btrfs_header header;
+	struct btrfs_key_ptr ptrs[];
+} __attribute__ ((__packed__));
+
+/* remember how we get to a node/leaf */
+struct btrfs_path {
+	__le64 offsets[BTRFS_MAX_LEVEL];
+	__le32 itemsnr[BTRFS_MAX_LEVEL];
+	__le32 slots[BTRFS_MAX_LEVEL];
+	/* remember last slot's item and data */
+	struct btrfs_item item;
+	u8 data[BTRFS_MAX_LEAF_SIZE];
+}__attribute__ ((__packed__));
+
+/* store logical offset to physical offset mapping */
+struct btrfs_chunk_map_item {
+	__le64 logical;
+	__le64 length;
+	__le64 devid;
+	__le64 physical;
+} __attribute__ ((__packed__));
+
+struct btrfs_chunk_map {
+	struct btrfs_chunk_map_item *map;
+	__le32 map_length;
+	__le32 cur_length;
+} __attribute__ ((__packed__));;
+
+struct btrfs_timespec {
+	__le64 sec;
+	__le32 nsec;
+} __attribute__ ((__packed__));
+
+struct btrfs_inode_item {
+	/* nfs style generation number */
+	__le64 generation;
+	/* transid that last touched this inode */
+	__le64 transid;
+	__le64 size;
+	__le64 nbytes;
+	__le64 block_group;
+	__le32 nlink;
+	__le32 uid;
+	__le32 gid;
+	__le32 mode;
+	__le64 rdev;
+	__le64 flags;
+
+	/* modification sequence number for NFS */
+	__le64 sequence;
+
+	/*
+	 * a little future expansion, for more than this we can
+	 * just grow the inode item and version it
+	 */
+	__le64 reserved[4];
+	struct btrfs_timespec atime;
+	struct btrfs_timespec ctime;
+	struct btrfs_timespec mtime;
+	struct btrfs_timespec otime;
+} __attribute__ ((__packed__));
+
+struct btrfs_root_item {
+	struct btrfs_inode_item inode;
+	__le64 generation;
+	__le64 root_dirid;
+	__le64 bytenr;
+	__le64 byte_limit;
+	__le64 bytes_used;
+	__le64 last_snapshot;
+	__le64 flags;
+	__le32 refs;
+	struct btrfs_disk_key drop_progress;
+	u8 drop_level;
+	u8 level;
+} __attribute__ ((__packed__));
+
+struct btrfs_dir_item {
+	struct btrfs_disk_key location;
+	__le64 transid;
+	__le16 data_len;
+	__le16 name_len;
+	u8 type;
+} __attribute__ ((__packed__));
+
+struct btrfs_file_extent_item {
+	__le64 generation;
+	__le64 ram_bytes;
+	u8 compression;
+	u8 encryption;
+	__le16 other_encoding; /* spare for later use */
+	u8 type;
+	__le64 disk_bytenr;
+	__le64 disk_num_bytes;
+	__le64 offset;
+	__le64 num_bytes;
+} __attribute__ ((__packed__));
+
+struct btrfs_root_ref {
+	__le64 dirid;
+	__le64 sequence;
+	__le16 name_len;
+} __attribute__ ((__packed__));
+
+/*
+ * btrfs private inode information
+ */
+struct btrfs_pvt_inode {
+    __le64 offset;
+}__attribute__ ((__packed__));
+
+void btrfs_set_blk_dev(block_dev_desc_t* rbdd , disk_partition_t *info);
+int btrfs_fs_init(struct fs_info *fs);
+void put_inode(struct inode *inode);
+struct inode *alloc_inode(struct fs_info *fs, uint32_t ino, size_t data);
+int btrfs_open_file(const char *name, struct com32_filedata *filedata);
+int getfssec(struct com32_filedata *filedata, char * buf);
+uint32_t generic_getfssec(struct file *file, char *buf,
+                          int sectors, char *have_more);
+#define PVT(i) ((struct btrfs_pvt_inode *)((i)->pvt))
+static inline __le32 next_psector(__le32 psector, uint32_t skip)
+{
+    if (EXTENT_SPECIAL(psector))
+        return psector;
+    else
+        return psector + skip;
+}
+
+static inline __le32 next_pstart(const struct extent *e)
+{
+    return next_psector(e->pstart, e->len);
+}
+
+/*
+ * Our definition of "not whitespace"
+ */
+static inline char not_whitespace(char c)
+{
+  return (unsigned char)c > ' ';
+}
+
+static inline struct inode *get_inode(struct inode *inode)
+{
+    inode->refcnt++;
+    return inode;
+}
+
+
+#endif
diff --git a/include/config_fallbacks.h b/include/config_fallbacks.h
index bfb9680..28a0a66 100644
--- a/include/config_fallbacks.h
+++ b/include/config_fallbacks.h
@@ -26,4 +26,8 @@ 
 #define CONFIG_EXT4_WRITE
 #endif
 
+#if defined(CONFIG_CMD_BTR) && !defined(CONFIG_FS_BTR)
+#define CONFIG_FS_BTR
+#endif
+
 #endif	/* __CONFIG_FALLBACKS_H */
diff --git a/include/crc32c.h b/include/crc32c.h
new file mode 100644
index 0000000..d04916e
--- /dev/null
+++ b/include/crc32c.h
@@ -0,0 +1,48 @@ 
+/*
+ * Copied from Linux kernel crypto/crc32c.c
+ * Copyright (c) 2004 Cisco Systems, Inc.
+ * Copyright (c) 2008 Herbert Xu <herbert@gondor.apana.org.au>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the Free
+ * Software Foundation; either version 2 of the License, or (at your option)
+ * any later version.
+ *
+ */
+
+/*
+ * This is the CRC-32C table
+ * Generated with:
+ * width = 32 bits
+ * poly = 0x1EDC6F41
+ * reflect input bytes = true
+ * reflect output bytes = true
+ */
+
+/*
+ * Steps through buffer one byte at at time, calculates reflected
+ * crc using table.
+ */
+
+static inline u32 crc32c_cal(u32 crc, const char *data, size_t length, u32 *crc32c_table)
+{
+	while (length--)
+		crc = crc32c_table[(u8)(crc ^ *data++)] ^ (crc >> 8);
+
+	return crc;
+}
+
+static inline void crc32c_init(u32 *crc32c_table, u32 pol)
+{
+	int i, j;
+	u32 v;
+	const u32 poly = pol; /* Bit-reflected CRC32C polynomial */
+
+	for (i = 0; i < 256; i++) {
+		v = i;
+		for (j = 0; j < 8; j++) {
+			v = (v >> 1) ^ ((v & 1) ? poly : 0);
+		}
+		crc32c_table[i] = v;
+	}
+}
diff --git a/include/fs.h b/include/fs.h
index 4f30a38..3a0e7d4 100644
--- a/include/fs.h
+++ b/include/fs.h
@@ -21,6 +21,7 @@ 
 #define FS_TYPE_ANY	0
 #define FS_TYPE_FAT	1
 #define FS_TYPE_EXT	2
+#define FS_TYPE_BTR	3
 
 /*
  * Tell the fs layer which block device an partition to use for future