From: Avantika Mathur <mathur@us.ibm.com>
Subject: Ext4 devel interlock meeting minutes (Nov. 22 2006)
Date: Wed, 22 Nov 2006 13:53:48 -0800
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Ext4 Developer Interlock Call: 11/22/06 minutes

Attendees: Mingming Cao, Eric Sandeen, Suparna Bhattacharya, Takashi Sa=
to, Jean-Pierre Dion, Val=C3=A9rie Cl=C3=A9ment, Avantika Mathur

- Online Defrag:
 -- Last week we determined that ioctl was the preferred=20
interface for the online defrag.
 -- Eric will send out an ovreview of the steps completed by XFS for fi=
le defragmentation.
 -- Last week Eric said that in XFS defrag implementation, you can't de=
frag a file that is open/being written to.  This was an incorrect assum=
ption. There will be more explanation in his mail.

- Preallocation:
 -- We need to decide which interface to use in the implementation
   * ioctl: simple solution preferred method for defrag and user in res=
ervation
   * posix_fallocate: writes zero to the first byte of every block; pro=
bably preferred solution
   * ftruncate: consistency across platforms may be an issue
 -- Possible parameters that would be used for preallocation would be f=
ile descriptor, number of blocks, and offset within file where blocks w=
ill be preallocated (if defrag and preallocation are implemented togeth=
er
 -- Suparna will send an email detailing all of the options, and some t=
houghts on implementation details to the list.
 -- Eric will send details on XFS's preallocation implementation to the=
 list
 -- Multiple block allocation patches will be used in preallocation imp=
lementation

- Features we'd like to see in Ext4 before code freeze:
 -- online defragmentation
 -- multiple block allocation
 -- big block group: Valerie has ported this to 2.6.19-rc6 and will sen=
d patches to the list tomorrow, and put updated e2fsprogs patches on Bu=
ll web site.
 -- large inode default for ext4
 -- large file support: Current max file size is 2 TB. Increase limit t=
o 16 TB by changing i_block ( patches have been sent by Takashi), then =
increase to more than 16 TB.  Changing the i_block to break 2TB limit m=
ay cause some application to break.

- We would like to document all features for Ext4 and sort dependencies=
 and priorities on the mailing list.