Re: [RFC][take 4] e2fsprogs: Add ext4migrate

[Andreas Dilger <adilger@clusterfs.com>]

On May 07, 2007  19:16 +0530, Aneesh Kumar K.V wrote:
> Theodore Tso wrote:
> >Actually, changing the inode size is actually going to be more useful
> >to a larger number of people, since they can use it today to support
> >in-inode EA's.  In addition, changing the inode size must be done
> >off-line, whereas it's not so clear that off-line conversion to
> >extents is the best way to go (more on that below).
> 
> That way we don't need to add kernel code that convert ext3 inode to 
> ext4 inode while defragmentation. Last time i looked at the online 
> defrag code, i was not able to figure out a easy way to take indirect 
> map inode as input, then defrag the same and write the result in extent 
> map.

I think the online defrag code _should_ be fairly easily made to handle
defrag of block-mapped files, so long as it is always creating extent-
mapped files in the end.  All that should be necessary is to have the
kernel read data from the block-mapped file and write it into the newly
mapped blocks.  That functionality needs to exist for a long time anyways
to support upgrading the filesystem so it shouldn't be a huge burden.

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