Hello,
I'm late with this issue, and I hope that the forum is not completely
wrong:
I had a desaster with one of my Linux partitions (Windows/98 shreddered
it), so I had to make the filesystem anew. I used mke2fs 1.26 from SuSE
8.0.
Being curious, I dumped the metadata after creation and found some odd
thing: For several allocation groups there was a gap in the free
blocks. First I thought it is intentional; maybe to put administrative
data in the moddle of the allocation group, but then I found that other
groups had no such gap. I'll attach the dump at the end.
If it's intentional, maybe add some documentation about the layout to
the manual pages; if it's a bug, it would be nice to see it fixed.
Regards,
Ulrich
mke2fs -v -L home -i 32768 /dev/sda6
Filesystem volume name: home
Last mounted on: <not available>
Filesystem UUID: 7a6cede5-d4df-42a6-9392-6421f5f2ee41
Filesystem magic number: 0xEF53
Filesystem revision #: 1 (dynamic)
Filesystem features: filetype sparse_super
Filesystem state: clean
Errors behavior: Continue
Filesystem OS type: Linux
Inode count: 129024
Block count: 1024135
Reserved block count: 51206
Free blocks: 1020018
Free inodes: 129013
First block: 0
Block size: 4096
Fragment size: 4096
Blocks per group: 32768
Fragments per group: 32768
Inodes per group: 4032
Inode blocks per group: 126
Last mount time: Thu Jan 1 01:00:00 1970
Last write time: Sun Jul 7 17:52:08 2002
Mount count: 0
Maximum mount count: 39
Last checked: Sun Jul 7 17:52:08 2002
Check interval: 15552000 (6 months)
Next check after: Fri Jan 3 16:52:08 2003
Reserved blocks uid: 0 (user root)
Reserved blocks gid: 0 (group root)
First inode: 11
Inode size: 128
Group 0: (Blocks 0-32767)
Primary Superblock at 0, Group Descriptors at 1-1
Block bitmap at 2 (+2), Inode bitmap at 3 (+3)
Inode table at 4-129 (+4)
32633 free blocks, 4021 free inodes, 2 directories
Free blocks: 135-32767
Free inodes: 12-4032
Group 1: (Blocks 32768-65535)
Backup Superblock at 32768, Group Descriptors at 32769-32769
Block bitmap at 32770 (+2), Inode bitmap at 32771 (+3)
Inode table at 32772-32897 (+4)
32638 free blocks, 4032 free inodes, 0 directories
Free blocks: 32898-65535
Free inodes: 4033-8064
Group 2: (Blocks 65536-98303)
Block bitmap at 65536 (+0), Inode bitmap at 65537 (+1)
Inode table at 65540-65665 (+4)
32640 free blocks, 4032 free inodes, 0 directories
Free blocks: 65538-65539, 65666-98303
Free inodes: 8065-12096
Group 3: (Blocks 98304-131071)
Backup Superblock at 98304, Group Descriptors at 98305-98305
Block bitmap at 98306 (+2), Inode bitmap at 98307 (+3)
Inode table at 98308-98433 (+4)
32638 free blocks, 4032 free inodes, 0 directories
Free blocks: 98434-131071
Free inodes: 12097-16128
Group 4: (Blocks 131072-163839)
Block bitmap at 131072 (+0), Inode bitmap at 131073 (+1)
Inode table at 131076-131201 (+4)
32640 free blocks, 4032 free inodes, 0 directories
Free blocks: 131074-131075, 131202-163839
Free inodes: 16129-20160
Group 5: (Blocks 163840-196607)
Backup Superblock at 163840, Group Descriptors at 163841-163841
Block bitmap at 163842 (+2), Inode bitmap at 163843 (+3)
Inode table at 163844-163969 (+4)
32638 free blocks, 4032 free inodes, 0 directories
Free blocks: 163970-196607
Free inodes: 20161-24192
Group 6: (Blocks 196608-229375)
Block bitmap at 196608 (+0), Inode bitmap at 196609 (+1)
Inode table at 196612-196737 (+4)
32640 free blocks, 4032 free inodes, 0 directories
Free blocks: 196610-196611, 196738-229375
Free inodes: 24193-28224
Group 7: (Blocks 229376-262143)
Backup Superblock at 229376, Group Descriptors at 229377-229377
Block bitmap at 229378 (+2), Inode bitmap at 229379 (+3)
Inode table at 229380-229505 (+4)
32638 free blocks, 4032 free inodes, 0 directories
Free blocks: 229506-262143
Free inodes: 28225-32256
Group 8: (Blocks 262144-294911)
Block bitmap at 262144 (+0), Inode bitmap at 262145 (+1)
Inode table at 262148-262273 (+4)
32640 free blocks, 4032 free inodes, 0 directories
Free blocks: 262146-262147, 262274-294911
Free inodes: 32257-36288
Group 9: (Blocks 294912-327679)
Backup Superblock at 294912, Group Descriptors at 294913-294913
Block bitmap at 294914 (+2), Inode bitmap at 294915 (+3)
Inode table at 294916-295041 (+4)
32638 free blocks, 4032 free inodes, 0 directories
Free blocks: 295042-327679
Free inodes: 36289-40320
Group 10: (Blocks 327680-360447)
Block bitmap at 327680 (+0), Inode bitmap at 327681 (+1)
Inode table at 327684-327809 (+4)
32640 free blocks, 4032 free inodes, 0 directories
Free blocks: 327682-327683, 327810-360447
Free inodes: 40321-44352
Group 11: (Blocks 360448-393215)
Block bitmap at 360448 (+0), Inode bitmap at 360449 (+1)
Inode table at 360452-360577 (+4)
32640 free blocks, 4032 free inodes, 0 directories
Free blocks: 360450-360451, 360578-393215
Free inodes: 44353-48384
Group 12: (Blocks 393216-425983)
Block bitmap at 393216 (+0), Inode bitmap at 393217 (+1)
Inode table at 393220-393345 (+4)
32640 free blocks, 4032 free inodes, 0 directories
Free blocks: 393218-393219, 393346-425983
Free inodes: 48385-52416
Group 13: (Blocks 425984-458751)
Block bitmap at 425984 (+0), Inode bitmap at 425985 (+1)
Inode table at 425988-426113 (+4)
32640 free blocks, 4032 free inodes, 0 directories
Free blocks: 425986-425987, 426114-458751
Free inodes: 52417-56448
Group 14: (Blocks 458752-491519)
Block bitmap at 458752 (+0), Inode bitmap at 458753 (+1)
Inode table at 458756-458881 (+4)
32640 free blocks, 4032 free inodes, 0 directories
Free blocks: 458754-458755, 458882-491519
Free inodes: 56449-60480
Group 15: (Blocks 491520-524287)
Block bitmap at 491520 (+0), Inode bitmap at 491521 (+1)
Inode table at 491524-491649 (+4)
32640 free blocks, 4032 free inodes, 0 directories
Free blocks: 491522-491523, 491650-524287
Free inodes: 60481-64512
Group 16: (Blocks 524288-557055)
Block bitmap at 524288 (+0), Inode bitmap at 524289 (+1)
Inode table at 524292-524417 (+4)
32640 free blocks, 4032 free inodes, 0 directories
Free blocks: 524290-524291, 524418-557055
Free inodes: 64513-68544
Group 17: (Blocks 557056-589823)
Block bitmap at 557056 (+0), Inode bitmap at 557057 (+1)
Inode table at 557060-557185 (+4)
32640 free blocks, 4032 free inodes, 0 directories
Free blocks: 557058-557059, 557186-589823
Free inodes: 68545-72576
Group 18: (Blocks 589824-622591)
Block bitmap at 589824 (+0), Inode bitmap at 589825 (+1)
Inode table at 589828-589953 (+4)
32640 free blocks, 4032 free inodes, 0 directories
Free blocks: 589826-589827, 589954-622591
Free inodes: 72577-76608
Group 19: (Blocks 622592-655359)
Block bitmap at 622592 (+0), Inode bitmap at 622593 (+1)
Inode table at 622596-622721 (+4)
32640 free blocks, 4032 free inodes, 0 directories
Free blocks: 622594-622595, 622722-655359
Free inodes: 76609-80640
Group 20: (Blocks 655360-688127)
Block bitmap at 655360 (+0), Inode bitmap at 655361 (+1)
Inode table at 655364-655489 (+4)
32640 free blocks, 4032 free inodes, 0 directories
Free blocks: 655362-655363, 655490-688127
Free inodes: 80641-84672
Group 21: (Blocks 688128-720895)
Block bitmap at 688128 (+0), Inode bitmap at 688129 (+1)
Inode table at 688132-688257 (+4)
32640 free blocks, 4032 free inodes, 0 directories
Free blocks: 688130-688131, 688258-720895
Free inodes: 84673-88704
Group 22: (Blocks 720896-753663)
Block bitmap at 720896 (+0), Inode bitmap at 720897 (+1)
Inode table at 720900-721025 (+4)
32640 free blocks, 4032 free inodes, 0 directories
Free blocks: 720898-720899, 721026-753663
Free inodes: 88705-92736
Group 23: (Blocks 753664-786431)
Block bitmap at 753664 (+0), Inode bitmap at 753665 (+1)
Inode table at 753668-753793 (+4)
32640 free blocks, 4032 free inodes, 0 directories
Free blocks: 753666-753667, 753794-786431
Free inodes: 92737-96768
Group 24: (Blocks 786432-819199)
Block bitmap at 786432 (+0), Inode bitmap at 786433 (+1)
Inode table at 786436-786561 (+4)
32640 free blocks, 4032 free inodes, 0 directories
Free blocks: 786434-786435, 786562-819199
Free inodes: 96769-100800
Group 25: (Blocks 819200-851967)
Backup Superblock at 819200, Group Descriptors at 819201-819201
Block bitmap at 819202 (+2), Inode bitmap at 819203 (+3)
Inode table at 819204-819329 (+4)
32638 free blocks, 4032 free inodes, 0 directories
Free blocks: 819330-851967
Free inodes: 100801-104832
Group 26: (Blocks 851968-884735)
Block bitmap at 851968 (+0), Inode bitmap at 851969 (+1)
Inode table at 851972-852097 (+4)
32640 free blocks, 4032 free inodes, 0 directories
Free blocks: 851970-851971, 852098-884735
Free inodes: 104833-108864
Group 27: (Blocks 884736-917503)
Backup Superblock at 884736, Group Descriptors at 884737-884737
Block bitmap at 884738 (+2), Inode bitmap at 884739 (+3)
Inode table at 884740-884865 (+4)
32638 free blocks, 4032 free inodes, 0 directories
Free blocks: 884866-917503
Free inodes: 108865-112896
Group 28: (Blocks 917504-950271)
Block bitmap at 917504 (+0), Inode bitmap at 917505 (+1)
Inode table at 917508-917633 (+4)
32640 free blocks, 4032 free inodes, 0 directories
Free blocks: 917506-917507, 917634-950271
Free inodes: 112897-116928
Group 29: (Blocks 950272-983039)
Block bitmap at 950272 (+0), Inode bitmap at 950273 (+1)
Inode table at 950276-950401 (+4)
32640 free blocks, 4032 free inodes, 0 directories
Free blocks: 950274-950275, 950402-983039
Free inodes: 116929-120960
Group 30: (Blocks 983040-1015807)
Block bitmap at 983040 (+0), Inode bitmap at 983041 (+1)
Inode table at 983044-983169 (+4)
32640 free blocks, 4032 free inodes, 0 directories
Free blocks: 983042-983043, 983170-1015807
Free inodes: 120961-124992
Group 31: (Blocks 1015808-1024134)
Block bitmap at 1015808 (+0), Inode bitmap at 1015809 (+1)
Inode table at 1015812-1015937 (+4)
8199 free blocks, 4032 free inodes, 0 directories
Free blocks: 1015810-1015811, 1015938-1024134
Free inodes: 124993-129024
On Sep 03, 2002 08:22 +0200, Ulrich Windl wrote:
> Being curious, I dumped the metadata after creation and found some odd
> thing: For several allocation groups there was a gap in the free
> blocks. First I thought it is intentional; maybe to put administrative
> data in the moddle of the allocation group, but then I found that other
> groups had no such gap. I'll attach the dump at the end.
>
> If it's intentional, maybe add some documentation about the layout to
> the manual pages; if it's a bug, it would be nice to see it fixed.
It _is_ intentional. The groups which have a gap do not have a backup
superblock or group descriptor table.
Cheers, Andreas
--
Andreas Dilger
http://www-mddsp.enel.ucalgary.ca/People/adilger/
http://sourceforge.net/projects/ext2resize/