2007-07-11 14:00:38

by Suzuki

[permalink] [raw]
Subject: Ext3 onlie resize failure due to small journal size

Hi Andreas,

Trying to resize a mounted ext3 filesystem fails due to small journal size.

Background :

The filesystem was created with default values, except blocksize = 4K on
a LV partition. Later we tried extended the partition to +16M and tried
to resize the fs using resize2fs, while it was mounted.

[[email protected] ~]# resize2fs /dev/mapper/testvg-tmp
resize2fs 1.39 (29-May-2006)
Filesystem at /dev/mapper/testvg-tmp is mounted on /tmp; on-line
resizing required
Performing an on-line resize of /dev/mapper/testvg-tmp to 186368 (4k)
blocks.
resize2fs: No space left on device While trying to add group #4

Analysis :

While adding the new blockgroup, inside setup_new_group_blocks() we hit
the limit because we are requesting for a a credit value of 2 +
sbi->s_itb_per_group which in the case of the file system below is 1026
while the max_transaction credits possible is 1024 for the fs.

journal->j_maxlen = inode->i_size / blocksize = 16M/4K = 4K

journal->j_max_transaction_buffers = journal->j_maxlen / 4 = 1K

journal->j_max_transaction_buffers = 1024.




# dumpe2fs /dev/mapper/testvg-tmp
dumpe2fs 1.39 (29-May-2006)
Filesystem volume name: <none>
Last mounted on: <not available>
Filesystem UUID: 7d82f07b-cb22-4c7d-b290-a35749121bbb
Filesystem magic number: 0xEF53
Filesystem revision #: 1 (dynamic)
Filesystem features: has_journal resize_inode dir_index filetype
needs_recovery sparse_super large_file
Default mount options: (none)
Filesystem state: clean
Errors behavior: Continue
Filesystem OS type: Linux
Inode count: 131072
Block count: 131072
Reserved block count: 6553
Free blocks: 122753
Free inodes: 131056
First block: 0
Block size: 4096
Fragment size: 4096
Reserved GDT blocks: 31
Blocks per group: 32768
Fragments per group: 32768
Inodes per group: 32768
Inode blocks per group: 1024
Filesystem created: Mon Jul 9 00:09:23 2007
Last mount time: Tue Jul 10 02:44:44 2007
Last write time: Tue Jul 10 02:44:44 2007
Mount count: 7
Maximum mount count: 33
Last checked: Mon Jul 9 00:09:23 2007
Check interval: 15552000 (6 months)
Next check after: Sat Jan 5 00:09:23 2008
Reserved blocks uid: 0 (user root)
Reserved blocks gid: 0 (group root)
First inode: 11
Inode size: 128
Journal inode: 8
Default directory hash: tea
Directory Hash Seed: 0a57077d-9778-4f3a-8605-7f0c86f18d8a
Journal backup: inode blocks
Journal size: 16M


Group 0: (Blocks 0-32767)
Primary superblock at 0, Group descriptors at 1-1
Reserved GDT blocks at 2-32
Block bitmap at 33 (+33), Inode bitmap at 34 (+34)
Inode table at 35-1058 (+35)
27600 free blocks, 32755 free inodes, 2 directories
Free blocks: 5168-32767
Free inodes: 14-32768
Group 1: (Blocks 32768-65535)
Backup superblock at 32768, Group descriptors at 32769-32769
Reserved GDT blocks at 32770-32800
Block bitmap at 32801 (+33), Inode bitmap at 32802 (+34)
Inode table at 32803-33826 (+35)
31708 free blocks, 32767 free inodes, 1 directories
Free blocks: 33828-65535
Free inodes: 32770-65536
Group 2: (Blocks 65536-98303)
Block bitmap at 65536 (+0), Inode bitmap at 65537 (+1)
Inode table at 65538-66561 (+2)
31740 free blocks, 32764 free inodes, 2 directories
Free blocks: 66562-83967, 83969-94207, 94209-98303
Free inodes: 65541-98304
Group 3: (Blocks 98304-131071)
Backup superblock at 98304, Group descriptors at 98305-98305
Reserved GDT blocks at 98306-98336
Block bitmap at 98337 (+33), Inode bitmap at 98338 (+34)
Inode table at 98339-99362 (+35)
31704 free blocks, 32766 free inodes, 1 directories
Free blocks: 99363-126976, 126982-131071
Free inodes: 98305, 98308-131072



Is this a supported operation ? If yes, what could be the best way to
fix it ?

Resizing the journal is not supported at the moment :(.

Thoughts ?

Thanks

Suzuki
IBM Linux Technology Centre


2007-07-11 19:47:23

by Kalpak Shah

[permalink] [raw]
Subject: Re: Ext3 onlie resize failure due to small journal size

On Wed, 2007-07-11 at 19:30 +0530, Suzuki wrote:
> Hi Andreas,
>
> Trying to resize a mounted ext3 filesystem fails due to small journal size.

A similar problem was discussed in an earlier thread "JBD: ext2online
wants too many credits (744 > 256)". The problem here is that the
maximum allowed transaction size is 4MB while a bigger transaction is
required to resize the filesystem.

In your case, you can delete the journal using "tune2fs -O ^has_journal
<dev>" and add a bigger journal "tune2fs -J size=16M <dev>". I think
this will solve your problem.

Thanks,
Kalpak.

>
> Background :
>
> The filesystem was created with default values, except blocksize = 4K on
> a LV partition. Later we tried extended the partition to +16M and tried
> to resize the fs using resize2fs, while it was mounted.
>
> [[email protected] ~]# resize2fs /dev/mapper/testvg-tmp
> resize2fs 1.39 (29-May-2006)
> Filesystem at /dev/mapper/testvg-tmp is mounted on /tmp; on-line
> resizing required
> Performing an on-line resize of /dev/mapper/testvg-tmp to 186368 (4k)
> blocks.
> resize2fs: No space left on device While trying to add group #4
>
> Analysis :
>
> While adding the new blockgroup, inside setup_new_group_blocks() we hit
> the limit because we are requesting for a a credit value of 2 +
> sbi->s_itb_per_group which in the case of the file system below is 1026
> while the max_transaction credits possible is 1024 for the fs.
>
> journal->j_maxlen = inode->i_size / blocksize = 16M/4K = 4K
>
> journal->j_max_transaction_buffers = journal->j_maxlen / 4 = 1K
>
> journal->j_max_transaction_buffers = 1024.
>
>
>
>
> # dumpe2fs /dev/mapper/testvg-tmp
> dumpe2fs 1.39 (29-May-2006)
> Filesystem volume name: <none>
> Last mounted on: <not available>
> Filesystem UUID: 7d82f07b-cb22-4c7d-b290-a35749121bbb
> Filesystem magic number: 0xEF53
> Filesystem revision #: 1 (dynamic)
> Filesystem features: has_journal resize_inode dir_index filetype
> needs_recovery sparse_super large_file
> Default mount options: (none)
> Filesystem state: clean
> Errors behavior: Continue
> Filesystem OS type: Linux
> Inode count: 131072
> Block count: 131072
> Reserved block count: 6553
> Free blocks: 122753
> Free inodes: 131056
> First block: 0
> Block size: 4096
> Fragment size: 4096
> Reserved GDT blocks: 31
> Blocks per group: 32768
> Fragments per group: 32768
> Inodes per group: 32768
> Inode blocks per group: 1024
> Filesystem created: Mon Jul 9 00:09:23 2007
> Last mount time: Tue Jul 10 02:44:44 2007
> Last write time: Tue Jul 10 02:44:44 2007
> Mount count: 7
> Maximum mount count: 33
> Last checked: Mon Jul 9 00:09:23 2007
> Check interval: 15552000 (6 months)
> Next check after: Sat Jan 5 00:09:23 2008
> Reserved blocks uid: 0 (user root)
> Reserved blocks gid: 0 (group root)
> First inode: 11
> Inode size: 128
> Journal inode: 8
> Default directory hash: tea
> Directory Hash Seed: 0a57077d-9778-4f3a-8605-7f0c86f18d8a
> Journal backup: inode blocks
> Journal size: 16M
>
>
> Group 0: (Blocks 0-32767)
> Primary superblock at 0, Group descriptors at 1-1
> Reserved GDT blocks at 2-32
> Block bitmap at 33 (+33), Inode bitmap at 34 (+34)
> Inode table at 35-1058 (+35)
> 27600 free blocks, 32755 free inodes, 2 directories
> Free blocks: 5168-32767
> Free inodes: 14-32768
> Group 1: (Blocks 32768-65535)
> Backup superblock at 32768, Group descriptors at 32769-32769
> Reserved GDT blocks at 32770-32800
> Block bitmap at 32801 (+33), Inode bitmap at 32802 (+34)
> Inode table at 32803-33826 (+35)
> 31708 free blocks, 32767 free inodes, 1 directories
> Free blocks: 33828-65535
> Free inodes: 32770-65536
> Group 2: (Blocks 65536-98303)
> Block bitmap at 65536 (+0), Inode bitmap at 65537 (+1)
> Inode table at 65538-66561 (+2)
> 31740 free blocks, 32764 free inodes, 2 directories
> Free blocks: 66562-83967, 83969-94207, 94209-98303
> Free inodes: 65541-98304
> Group 3: (Blocks 98304-131071)
> Backup superblock at 98304, Group descriptors at 98305-98305
> Reserved GDT blocks at 98306-98336
> Block bitmap at 98337 (+33), Inode bitmap at 98338 (+34)
> Inode table at 98339-99362 (+35)
> 31704 free blocks, 32766 free inodes, 1 directories
> Free blocks: 99363-126976, 126982-131071
> Free inodes: 98305, 98308-131072
>
>
>
> Is this a supported operation ? If yes, what could be the best way to
> fix it ?
>
> Resizing the journal is not supported at the moment :(.
>
> Thoughts ?
>
> Thanks
>
> Suzuki
> IBM Linux Technology Centre
>
>
> -
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2007-07-12 05:07:44

by Andreas Dilger

[permalink] [raw]
Subject: Re: Ext3 onlie resize failure due to small journal size

On Jul 11, 2007 19:30 +0530, Suzuki wrote:
> Trying to resize a mounted ext3 filesystem fails due to small journal size.
>
> Background :
>
> The filesystem was created with default values, except blocksize = 4K on
> a LV partition. Later we tried extended the partition to +16M and tried
> to resize the fs using resize2fs, while it was mounted.
>
> While adding the new blockgroup, inside setup_new_group_blocks() we hit
> the limit because we are requesting for a a credit value of 2 +
> sbi->s_itb_per_group which in the case of the file system below is 1026
> while the max_transaction credits possible is 1024 for the fs.
>
> journal->j_maxlen = inode->i_size / blocksize = 16M/4K = 4K
>
> journal->j_max_transaction_buffers = journal->j_maxlen / 4 = 1K
>
> journal->j_max_transaction_buffers = 1024.
>
> Is this a supported operation ? If yes, what could be the best way to
> fix it ?
>
> Resizing the journal is not supported at the moment :(.

You can't do a journal resize online, but you can wait until your next
outage and resize the journal at that time. Even a few extra blocks
would be enough. I guess this is a corner case that hasn't been hit
before. It might make sense to have the ext2fs_figure_journal_size()
take this into account when making the filesystem?

Cheers, Andreas
--
Andreas Dilger
Principal Software Engineer
Cluster File Systems, Inc.

2007-07-12 05:10:33

by Aneesh Kumar K.V

[permalink] [raw]
Subject: Re: Ext3 onlie resize failure due to small journal size



Andreas Dilger wrote:
> On Jul 11, 2007 19:30 +0530, Suzuki wrote:
>> Trying to resize a mounted ext3 filesystem fails due to small journal size.
>>
>> Background :
>>
>> The filesystem was created with default values, except blocksize = 4K on
>> a LV partition. Later we tried extended the partition to +16M and tried
>> to resize the fs using resize2fs, while it was mounted.
>>
>> While adding the new blockgroup, inside setup_new_group_blocks() we hit
>> the limit because we are requesting for a a credit value of 2 +
>> sbi->s_itb_per_group which in the case of the file system below is 1026
>> while the max_transaction credits possible is 1024 for the fs.
>>
>> journal->j_maxlen = inode->i_size / blocksize = 16M/4K = 4K
>>
>> journal->j_max_transaction_buffers = journal->j_maxlen / 4 = 1K
>>
>> journal->j_max_transaction_buffers = 1024.
>>
>> Is this a supported operation ? If yes, what could be the best way to
>> fix it ?
>>
>> Resizing the journal is not supported at the moment :(.
>
> You can't do a journal resize online, but you can wait until your next
> outage and resize the journal at that time. Even a few extra blocks
> would be enough. I guess this is a corner case that hasn't been hit
> before. It might make sense to have the ext2fs_figure_journal_size()
> take this into account when making the filesystem?
>
>

That't true. I was looking at it. I guess we should make sure we can
ask for a credit same as inode tables block per group + some extra.

Will try to see i can cook a patch.

-aneesh