Hi btrfs folks,
I am working on btrfs filesystem on how it manages the free space. And found out btrfs maintain a ctree which manages the physical location of the chunks and stripes of the filesystem.
Btrfs-debug-tree also gives the information on the chunk tree
I created btrfs on single device and two device.I have attached the output of both on running btrfs-debug-tree.
For single device sum of all the length in the chunks will add upto the total used bytes which is expected behavior.
But for two devices sum of all lengths in the chunks does not add to the total bytes .Am I missing something .
Also I notice that for the second device the superblock location 0x10000 is not considered as used .
I would be really grateful if you folks can answer my query.
I hav run these tests on SLES11-sp2-x86
Kernel 3.0.13.0.27-default
If you want any further clarification I would be wiiling to help you guys on this.
Thanks,
Santosh Hosamani
________________________________
http://www.mindtree.com/email/disclaimer.html
root tree
leaf 29364224 items 9 free space 2349 generation 4 owner 1
fs uuid 22d1b011-b53a-423f-9f61-ca6d5f4192c7
chunk uuid e7e5467e-ef4e-4b47-ac37-198c1cc575b9
item 0 key (EXTENT_TREE ROOT_ITEM 0) itemoff 3756 itemsize 239
root data bytenr 29368320 level 0 dirid 0 refs 1 gen 4
item 1 key (DEV_TREE ROOT_ITEM 0) itemoff 3517 itemsize 239
root data bytenr 29372416 level 0 dirid 0 refs 1 gen 4
item 2 key (FS_TREE INODE_REF 6) itemoff 3500 itemsize 17
inode ref index 0 namelen 7 name: default
item 3 key (FS_TREE ROOT_ITEM 0) itemoff 3261 itemsize 239
root data bytenr 29360128 level 0 dirid 256 refs 1 gen 4
item 4 key (ROOT_TREE_DIR INODE_ITEM 0) itemoff 3101 itemsize 160
inode generation 3 size 0 block group 0 mode 40555 links 1
item 5 key (ROOT_TREE_DIR INODE_REF 6) itemoff 3089 itemsize 12
inode ref index 0 namelen 2 name: ..
item 6 key (ROOT_TREE_DIR DIR_ITEM 2378154706) itemoff 3052 itemsize 37
location key (FS_TREE ROOT_ITEM 18446744073709551615) type 2
namelen 7 datalen 0 name: default
item 7 key (CSUM_TREE ROOT_ITEM 0) itemoff 2813 itemsize 239
root data bytenr 29376512 level 0 dirid 0 refs 1 gen 4
item 8 key (DATA_RELOC_TREE ROOT_ITEM 0) itemoff 2574 itemsize 239
root data bytenr 29380608 level 0 dirid 256 refs 1 gen 4
chunk tree
leaf 20971520 items 8 free space 3023 generation 4 owner 3
fs uuid 22d1b011-b53a-423f-9f61-ca6d5f4192c7
chunk uuid e7e5467e-ef4e-4b47-ac37-198c1cc575b9
item 0 key (DEV_ITEMS DEV_ITEM 1) itemoff 3897 itemsize 98
dev item devid 1 total_bytes 3221225472 bytes used 673579008
item 1 key (DEV_ITEMS DEV_ITEM 2) itemoff 3799 itemsize 98
dev item devid 2 total_bytes 3221225472 bytes used 652607488
item 2 key (FIRST_CHUNK_TREE CHUNK_ITEM 0) itemoff 3719 itemsize 80
chunk length 4194304 owner 2 type 2 num_stripes 1
stripe 0 devid 1 offset 0
item 3 key (FIRST_CHUNK_TREE CHUNK_ITEM 4194304) itemoff 3639 itemsize 80
chunk length 8388608 owner 2 type 4 num_stripes 1
stripe 0 devid 1 offset 4194304
item 4 key (FIRST_CHUNK_TREE CHUNK_ITEM 12582912) itemoff 3559 itemsize 80
chunk length 8388608 owner 2 type 1 num_stripes 1
stripe 0 devid 1 offset 12582912
item 5 key (FIRST_CHUNK_TREE CHUNK_ITEM 20971520) itemoff 3447 itemsize 112
chunk length 8388608 owner 2 type 18 num_stripes 2
stripe 0 devid 2 offset 1048576
stripe 1 devid 1 offset 20971520
item 6 key (FIRST_CHUNK_TREE CHUNK_ITEM 29360128) itemoff 3335 itemsize 112
chunk length 322109440 owner 2 type 20 num_stripes 2
stripe 0 devid 2 offset 9437184
stripe 1 devid 1 offset 29360128
item 7 key (FIRST_CHUNK_TREE CHUNK_ITEM 351469568) itemoff 3223 itemsize 112
chunk length 644218880 owner 2 type 9 num_stripes 2
stripe 0 devid 2 offset 331546624
stripe 1 devid 1 offset 351469568
extent tree key (EXTENT_TREE ROOT_ITEM 0)
leaf 29368320 items 13 free space 3169 generation 4 owner 2
fs uuid 22d1b011-b53a-423f-9f61-ca6d5f4192c7
chunk uuid e7e5467e-ef4e-4b47-ac37-198c1cc575b9
item 0 key (0 BLOCK_GROUP_ITEM 4194304) itemoff 3971 itemsize 24
block group used 0 chunk_objectid 256 flags 2
item 1 key (4194304 BLOCK_GROUP_ITEM 8388608) itemoff 3947 itemsize 24
block group used 0 chunk_objectid 256 flags 4
item 2 key (12582912 BLOCK_GROUP_ITEM 8388608) itemoff 3923 itemsize 24
block group used 0 chunk_objectid 256 flags 1
item 3 key (20971520 EXTENT_ITEM 4096) itemoff 3872 itemsize 51
extent refs 1 gen 4 flags 2
tree block key (1 d8 1) level 0
tree block backref root 3
item 4 key (20971520 BLOCK_GROUP_ITEM 8388608) itemoff 3848 itemsize 24
block group used 4096 chunk_objectid 256 flags 18
item 5 key (29360128 EXTENT_ITEM 4096) itemoff 3797 itemsize 51
extent refs 1 gen 4 flags 2
tree block key (256 1 0) level 0
tree block backref root 5
item 6 key (29360128 BLOCK_GROUP_ITEM 322109440) itemoff 3773 itemsize 24
block group used 24576 chunk_objectid 256 flags 20
item 7 key (29364224 EXTENT_ITEM 4096) itemoff 3722 itemsize 51
extent refs 1 gen 4 flags 2
tree block key (2 84 0) level 0
tree block backref root 1
item 8 key (29368320 EXTENT_ITEM 4096) itemoff 3671 itemsize 51
extent refs 1 gen 4 flags 2
tree block key (0 c0 4194304) level 0
tree block backref root 2
item 9 key (29372416 EXTENT_ITEM 4096) itemoff 3620 itemsize 51
extent refs 1 gen 4 flags 2
tree block key (1 cc 0) level 0
tree block backref root 4
item 10 key (29376512 EXTENT_ITEM 4096) itemoff 3569 itemsize 51
extent refs 1 gen 4 flags 2
tree block key (0 0 0) level 0
tree block backref root 7
item 11 key (29380608 EXTENT_ITEM 4096) itemoff 3518 itemsize 51
extent refs 1 gen 4 flags 2
tree block key (256 1 0) level 0
tree block backref root 18446744073709551607
item 12 key (351469568 BLOCK_GROUP_ITEM 644218880) itemoff 3494 itemsize 24
block group used 0 chunk_objectid 256 flags 9
device tree key (DEV_TREE ROOT_ITEM 0)
leaf 29372416 items 9 free space 3338 generation 4 owner 4
fs uuid 22d1b011-b53a-423f-9f61-ca6d5f4192c7
chunk uuid e7e5467e-ef4e-4b47-ac37-198c1cc575b9
item 0 key (1 DEV_EXTENT 0) itemoff 3947 itemsize 48
dev extent chunk_tree 3
chunk objectid 256 chunk offset 0 length 4194304
item 1 key (1 DEV_EXTENT 4194304) itemoff 3899 itemsize 48
dev extent chunk_tree 3
chunk objectid 256 chunk offset 4194304 length 8388608
item 2 key (1 DEV_EXTENT 12582912) itemoff 3851 itemsize 48
dev extent chunk_tree 3
chunk objectid 256 chunk offset 12582912 length 8388608
item 3 key (1 DEV_EXTENT 20971520) itemoff 3803 itemsize 48
dev extent chunk_tree 3
chunk objectid 256 chunk offset 20971520 length 8388608
item 4 key (1 DEV_EXTENT 29360128) itemoff 3755 itemsize 48
dev extent chunk_tree 3
chunk objectid 256 chunk offset 29360128 length 322109440
item 5 key (1 DEV_EXTENT 351469568) itemoff 3707 itemsize 48
dev extent chunk_tree 3
chunk objectid 256 chunk offset 351469568 length 322109440
item 6 key (2 DEV_EXTENT 1048576) itemoff 3659 itemsize 48
dev extent chunk_tree 3
chunk objectid 256 chunk offset 20971520 length 8388608
item 7 key (2 DEV_EXTENT 9437184) itemoff 3611 itemsize 48
dev extent chunk_tree 3
chunk objectid 256 chunk offset 29360128 length 322109440
item 8 key (2 DEV_EXTENT 331546624) itemoff 3563 itemsize 48
dev extent chunk_tree 3
chunk objectid 256 chunk offset 351469568 length 322109440
fs tree key (FS_TREE ROOT_ITEM 0)
leaf 29360128 items 2 free space 3773 generation 4 owner 5
fs uuid 22d1b011-b53a-423f-9f61-ca6d5f4192c7
chunk uuid e7e5467e-ef4e-4b47-ac37-198c1cc575b9
item 0 key (256 INODE_ITEM 0) itemoff 3835 itemsize 160
inode generation 3 size 0 block group 0 mode 40555 links 1
item 1 key (256 INODE_REF 256) itemoff 3823 itemsize 12
inode ref index 0 namelen 2 name: ..
checksum tree key (CSUM_TREE ROOT_ITEM 0)
leaf 29376512 items 0 free space 3995 generation 4 owner 7
fs uuid 22d1b011-b53a-423f-9f61-ca6d5f4192c7
chunk uuid e7e5467e-ef4e-4b47-ac37-198c1cc575b9
data reloc tree key (DATA_RELOC_TREE ROOT_ITEM 0)
leaf 29380608 items 2 free space 3773 generation 4 owner 18446744073709551607
fs uuid 22d1b011-b53a-423f-9f61-ca6d5f4192c7
chunk uuid e7e5467e-ef4e-4b47-ac37-198c1cc575b9
item 0 key (256 INODE_ITEM 0) itemoff 3835 itemsize 160
inode generation 3 size 0 block group 0 mode 40555 links 1
item 1 key (256 INODE_REF 256) itemoff 3823 itemsize 12
inode ref index 0 namelen 2 name: ..
total bytes 6442450944
bytes used 28672
uuid 22d1b011-b53a-423f-9f61-ca6d5f4192c7
Btrfs v0.19+
root tree
leaf 29364224 items 9 free space 2349 generation 4 owner 1
fs uuid 6dcc7c2b-6b77-4c9d-bafb-201627ef82bf
chunk uuid e279f69e-7a5f-401a-b56a-755134965695
item 0 key (EXTENT_TREE ROOT_ITEM 0) itemoff 3756 itemsize 239
root data bytenr 29368320 level 0 dirid 0 refs 1 gen 4
item 1 key (DEV_TREE ROOT_ITEM 0) itemoff 3517 itemsize 239
root data bytenr 29372416 level 0 dirid 0 refs 1 gen 4
item 2 key (FS_TREE INODE_REF 6) itemoff 3500 itemsize 17
inode ref index 0 namelen 7 name: default
item 3 key (FS_TREE ROOT_ITEM 0) itemoff 3261 itemsize 239
root data bytenr 29360128 level 0 dirid 256 refs 1 gen 4
item 4 key (ROOT_TREE_DIR INODE_ITEM 0) itemoff 3101 itemsize 160
inode generation 3 size 0 block group 0 mode 40555 links 1
item 5 key (ROOT_TREE_DIR INODE_REF 6) itemoff 3089 itemsize 12
inode ref index 0 namelen 2 name: ..
item 6 key (ROOT_TREE_DIR DIR_ITEM 2378154706) itemoff 3052 itemsize 37
location key (FS_TREE ROOT_ITEM 18446744073709551615) type 2
namelen 7 datalen 0 name: default
item 7 key (CSUM_TREE ROOT_ITEM 0) itemoff 2813 itemsize 239
root data bytenr 29376512 level 0 dirid 0 refs 1 gen 4
item 8 key (DATA_RELOC_TREE ROOT_ITEM 0) itemoff 2574 itemsize 239
root data bytenr 29380608 level 0 dirid 256 refs 1 gen 4
chunk tree
leaf 20971520 items 6 free space 3283 generation 4 owner 3
fs uuid 6dcc7c2b-6b77-4c9d-bafb-201627ef82bf
chunk uuid e279f69e-7a5f-401a-b56a-755134965695
item 0 key (DEV_ITEMS DEV_ITEM 1) itemoff 3897 itemsize 98
dev item devid 1 total_bytes 3221225472 bytes used 359792640
item 1 key (FIRST_CHUNK_TREE CHUNK_ITEM 0) itemoff 3817 itemsize 80
chunk length 4194304 owner 2 type 2 num_stripes 1
stripe 0 devid 1 offset 0
item 2 key (FIRST_CHUNK_TREE CHUNK_ITEM 4194304) itemoff 3737 itemsize 80
chunk length 8388608 owner 2 type 4 num_stripes 1
stripe 0 devid 1 offset 4194304
item 3 key (FIRST_CHUNK_TREE CHUNK_ITEM 12582912) itemoff 3657 itemsize 80
chunk length 8388608 owner 2 type 1 num_stripes 1
stripe 0 devid 1 offset 12582912
item 4 key (FIRST_CHUNK_TREE CHUNK_ITEM 20971520) itemoff 3545 itemsize 112
chunk length 8388608 owner 2 type 34 num_stripes 2
stripe 0 devid 1 offset 20971520
stripe 1 devid 1 offset 29360128
item 5 key (FIRST_CHUNK_TREE CHUNK_ITEM 29360128) itemoff 3433 itemsize 112
chunk length 161021952 owner 2 type 36 num_stripes 2
stripe 0 devid 1 offset 37748736
stripe 1 devid 1 offset 198770688
extent tree key (EXTENT_TREE ROOT_ITEM 0)
leaf 29368320 items 12 free space 3218 generation 4 owner 2
fs uuid 6dcc7c2b-6b77-4c9d-bafb-201627ef82bf
chunk uuid e279f69e-7a5f-401a-b56a-755134965695
item 0 key (0 BLOCK_GROUP_ITEM 4194304) itemoff 3971 itemsize 24
block group used 0 chunk_objectid 256 flags 2
item 1 key (4194304 BLOCK_GROUP_ITEM 8388608) itemoff 3947 itemsize 24
block group used 0 chunk_objectid 256 flags 4
item 2 key (12582912 BLOCK_GROUP_ITEM 8388608) itemoff 3923 itemsize 24
block group used 0 chunk_objectid 256 flags 1
item 3 key (20971520 EXTENT_ITEM 4096) itemoff 3872 itemsize 51
extent refs 1 gen 4 flags 2
tree block key (1 d8 1) level 0
tree block backref root 3
item 4 key (20971520 BLOCK_GROUP_ITEM 8388608) itemoff 3848 itemsize 24
block group used 4096 chunk_objectid 256 flags 34
item 5 key (29360128 EXTENT_ITEM 4096) itemoff 3797 itemsize 51
extent refs 1 gen 4 flags 2
tree block key (256 1 0) level 0
tree block backref root 5
item 6 key (29360128 BLOCK_GROUP_ITEM 161021952) itemoff 3773 itemsize 24
block group used 24576 chunk_objectid 256 flags 36
item 7 key (29364224 EXTENT_ITEM 4096) itemoff 3722 itemsize 51
extent refs 1 gen 4 flags 2
tree block key (2 84 0) level 0
tree block backref root 1
item 8 key (29368320 EXTENT_ITEM 4096) itemoff 3671 itemsize 51
extent refs 1 gen 4 flags 2
tree block key (0 c0 4194304) level 0
tree block backref root 2
item 9 key (29372416 EXTENT_ITEM 4096) itemoff 3620 itemsize 51
extent refs 1 gen 4 flags 2
tree block key (1 cc 0) level 0
tree block backref root 4
item 10 key (29376512 EXTENT_ITEM 4096) itemoff 3569 itemsize 51
extent refs 1 gen 4 flags 2
tree block key (0 0 0) level 0
tree block backref root 7
item 11 key (29380608 EXTENT_ITEM 4096) itemoff 3518 itemsize 51
extent refs 1 gen 4 flags 2
tree block key (256 1 0) level 0
tree block backref root 18446744073709551607
device tree key (DEV_TREE ROOT_ITEM 0)
leaf 29372416 items 7 free space 3484 generation 4 owner 4
fs uuid 6dcc7c2b-6b77-4c9d-bafb-201627ef82bf
chunk uuid e279f69e-7a5f-401a-b56a-755134965695
item 0 key (1 DEV_EXTENT 0) itemoff 3947 itemsize 48
dev extent chunk_tree 3
chunk objectid 256 chunk offset 0 length 4194304
item 1 key (1 DEV_EXTENT 4194304) itemoff 3899 itemsize 48
dev extent chunk_tree 3
chunk objectid 256 chunk offset 4194304 length 8388608
item 2 key (1 DEV_EXTENT 12582912) itemoff 3851 itemsize 48
dev extent chunk_tree 3
chunk objectid 256 chunk offset 12582912 length 8388608
item 3 key (1 DEV_EXTENT 20971520) itemoff 3803 itemsize 48
dev extent chunk_tree 3
chunk objectid 256 chunk offset 20971520 length 8388608
item 4 key (1 DEV_EXTENT 29360128) itemoff 3755 itemsize 48
dev extent chunk_tree 3
chunk objectid 256 chunk offset 20971520 length 8388608
item 5 key (1 DEV_EXTENT 37748736) itemoff 3707 itemsize 48
dev extent chunk_tree 3
chunk objectid 256 chunk offset 29360128 length 161021952
item 6 key (1 DEV_EXTENT 198770688) itemoff 3659 itemsize 48
dev extent chunk_tree 3
chunk objectid 256 chunk offset 29360128 length 161021952
fs tree key (FS_TREE ROOT_ITEM 0)
leaf 29360128 items 2 free space 3773 generation 4 owner 5
fs uuid 6dcc7c2b-6b77-4c9d-bafb-201627ef82bf
chunk uuid e279f69e-7a5f-401a-b56a-755134965695
item 0 key (256 INODE_ITEM 0) itemoff 3835 itemsize 160
inode generation 3 size 0 block group 0 mode 40555 links 1
item 1 key (256 INODE_REF 256) itemoff 3823 itemsize 12
inode ref index 0 namelen 2 name: ..
checksum tree key (CSUM_TREE ROOT_ITEM 0)
leaf 29376512 items 0 free space 3995 generation 4 owner 7
fs uuid 6dcc7c2b-6b77-4c9d-bafb-201627ef82bf
chunk uuid e279f69e-7a5f-401a-b56a-755134965695
data reloc tree key (DATA_RELOC_TREE ROOT_ITEM 0)
leaf 29380608 items 2 free space 3773 generation 4 owner 18446744073709551607
fs uuid 6dcc7c2b-6b77-4c9d-bafb-201627ef82bf
chunk uuid e279f69e-7a5f-401a-b56a-755134965695
item 0 key (256 INODE_ITEM 0) itemoff 3835 itemsize 160
inode generation 3 size 0 block group 0 mode 40555 links 1
item 1 key (256 INODE_REF 256) itemoff 3823 itemsize 12
inode ref index 0 namelen 2 name: ..
total bytes 3221225472
bytes used 28672
uuid 6dcc7c2b-6b77-4c9d-bafb-201627ef82bf
Btrfs v0.19+
