ext2/3 fragments support

ext2/3 fragments support

[Lorenzo Allegrucci]

Fragments support on ext2/3 filesystems seems disabled
or non fully functional.
Are there any plans to implement fragments?

Bye

Re: ext2/3 fragments support

[Andreas Dilger]

On Apr 10, 2003  21:35 +0000, Lorenzo Allegrucci wrote:
> Fragments support on ext2/3 filesystems seems disabled
> or non fully functional.
> Are there any plans to implement fragments?

They have never been enabled.  The "goal" is to imlement fragments as a
type of extended attribute, so that they can be packed into a single block
or inline in a larger inode (along with other EA data) instead of being
fixed-size hunks.

The first thing that needs doing is fixing the current ext2/3 EA sharing
scheme, which currently only shares blocks if they are identical and is
therefore only really useful for ACLs.

The best proposal so far for EA sharing is to put them into a directory-like
structure (maybe one dir per block group or something) and have the EA type
and data be packed inline into the directory (like the inode number and
filename are done with regular directories).  Each inode would also have a
"catalog" of the EAs that it has (itself an EA, either inline in a larger
inode or in the directory pointed to by, say, i_faddr).  Shared entries would
be like hard links pointed to by mutliple catalogs, with a refcount.

This was discussed on ext2-devel about a year ago, but no takers on the
implementation yet (I might eventually need to implement it this year if
nobody beats me to it, because we need better EAs than one per 4kB of disk).

Cheers, Andreas
--
Andreas Dilger
http://sourceforge.net/projects/ext2resize/
http://www-mddsp.enel.ucalgary.ca/People/adilger/

Re: ext2/3 fragments support

[Maciej Soltysiak]

> Are there any plans to implement fragments?
What are fragments?

Regards,
Maciej