the compressed file attribute

the compressed file attribute

[Pat LaVarre]

Does one of the Linux fs, other than ntfs, already let me distinguish
one file from another by a compressed attribute?  What I'm hoping to
find is:

Uncompressed files work same as always.

Compressed files appear to work same as always, but under the covers the
data of the file occupies more or less space according to how
compressible it is.  Random access within the file either sequentially
rewrites all the file or else garbage collects and defragments.

I ask here because I think Google mostly points me to file systems that
compress all files e.g. fs/cramfs/README Future Development doesn't
mention this twist, e.g. `ls fs | egrep -i nw5` is empty, ...

Compressing all files is not the same thing.  I don't want the file
system deciding for me which files to compress.

Pat LaVarre

Re: the compressed file attribute

[Phillip Lougher]

Pat LaVarre wrote:
> Does one of the Linux fs, other than ntfs, already let me distinguish
> one file from another by a compressed attribute?  What I'm hoping to
> find is:

> Compressing all files is not the same thing.  I don't want the file
> system deciding for me which files to compress.
> 

AFAIK e2compr is the only filesystem that does this 
(http://e2compr.sourceforge.net).  It seems to be intermittently 
maintained and the latest patch appears to be for 2.4.17.

CRAMFS, Squashfs, zisofs are read-only filesystems (you imply you want a 
rw filesystem), and compress all files.  JFFS2 is a compressed 
read-write filesystem for flash, but again it compresses all files.

FiST was mentioned a while back on this email group, they have a gzipfs 
(http://www.filesystems.org), but it is unclear from the documentation 
whether all files are compressed.


Phillip

Re: the compressed file attribute

[Erez Zadok]

In message <40199070.9040201@lougher.demon.co.uk>, Phillip Lougher writes:
> Pat LaVarre wrote:
[...]
> FiST was mentioned a while back on this email group, they have a gzipfs 
> (http://www.filesystems.org), but it is unclear from the documentation 
> whether all files are compressed.

Yes, fist's Gzipfs does compress all files.  However, it probably won't be
too difficult to make it look at the f/s below, and if it's ext2/3, check if
the compress flag is on or not, then selectively [de]compress files.

It would take a bit more effort to add chattr support to Gzipfs, so that you
can make files compressed or not on the fly: you'd have to trap the ext2/3
ioctl, then de/compress the entire file as needed, then pass the ioctl down
to ext2/3.

If there's enough interest in per-file compression, I'll consider it and try
to find resources to work on it.

Erez.

Re: the compressed file attribute

[H. Peter Anvin]

Followup to:  <40199070.9040201@lougher.demon.co.uk>
By author:    Phillip Lougher <phillip@lougher.demon.co.uk>
In newsgroup: linux.dev.fs.devel
> 
> CRAMFS, Squashfs, zisofs are read-only filesystems (you imply you want a 
> rw filesystem), and compress all files.
> 

zisofs only compresses files with the ZF RockRidge attribute.  A
zisofs filesystem can have an arbitrary mix of compressed and
uncompressed files; in fact, the default toolchain will not compress
files if they end up larger than the uncompressed version.

	-hpa

-- 
PGP public key available - finger hpa@zytor.com
Key fingerprint: 2047/2A960705 BA 03 D3 2C 14 A8 A8 BD  1E DF FE 69 EE 35 BD 74
"The earth is but one country, and mankind its citizens."  --  Bahá'u'lláh
Just Say No to Morden * The Shadows were defeated -- Babylon 5 is renewed!!
-
To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html

Re: the compressed file attribute

[Andreas Dilger]

On Jan 29, 2004  15:35 -0700, Pat LaVarre wrote:
> Does one of the Linux fs, other than ntfs, already let me distinguish
> one file from another by a compressed attribute?

Look for e2compr, which does this for ext2 and maybe ext3 (not sure).

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

Re: the compressed file attribute

[Yury V. Umanets]

On Fri, 2004-01-30 at 00:35, Pat LaVarre wrote:
> Does one of the Linux fs, other than ntfs, already let me distinguish
> one file from another by a compressed attribute?  What I'm hoping to
> find is:
> 
> Uncompressed files work same as always.
> 
> Compressed files appear to work same as always, but under the covers the
> data of the file occupies more or less space according to how
> compressible it is.  Random access within the file either sequentially
> rewrites all the file or else garbage collects and defragments.
> 
> I ask here because I think Google mostly points me to file systems that
> compress all files e.g. fs/cramfs/README Future Development doesn't
> mention this twist, e.g. `ls fs | egrep -i nw5` is empty, ...
> 
> Compressing all files is not the same thing.  I don't want the file
> system deciding for me which files to compress.
> 
> Pat LaVarre
Take a look onto reiser4. It has plugin based architecture and has so
called crypto-compress unix file plugin. 

Probably it is what you are looking for, though it is not stable yet...

> 
> 
> -
> To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
-- 
umka