Re: [prepatch] address_space-based writeback

Anton Altaparmakov
2002-04-28T03:04:01Z

At 16:53 27/04/02, Jan Harkes wrote:
>On Fri, Apr 12, 2002 at 08:57:17AM +0100, Anton Altaparmakov wrote:
> > Yet, this really begs the question of defining the concept of a file. I am
> > quite happy with files being the io entity in ntfs. It is just that each
> > file in ntfs can contain loads of different data holding attributes which
> > are all worth placing in address spaces. Granted, a dummy inode could be
> > setup for each of those which just means a lot of wasted ram but ntfs is
> > not that important so I have to take the penalty there. But if I also need
> > unique inode numbers in those dummy inodes then the overhead is becoming
> > very, very high...
>
>You could have all additional IO streams use the same inode number and
>use iget4. Several inodes can have the same i_ino and the additional
>argument would be a stream identifier that selects the correct 'IO
>identity'.

Great idea! I quickly looked into the implementation details and using
iget4/read_inode2 perfectly reconciles my ideas of using an address space
mapping for each ntfs attribute with the kernels requirement of using
inodes as the i/o entity by allowing a clean and unique mapping between
multiple inodes with the same inode numbers and their attributes and
address spaces.

I need to work out exactly how to do it but I will definitely go that way.
That will make everything nice and clean and get rid of the existing
kludges of passing around other types of objects instead of struct file *
to my various readpage functions. Also I will be able to have fewer
readpage functions... (-:

Thanks for the suggestion!

Best regards,

Anton

--
"I've not lost my mind. It's backed up on tape somewhere." - Unknown
--
Anton Altaparmakov <aia21 at cantab.net> (replace at with @)
Linux NTFS Maintainer / IRC: #ntfs on irc.openprojects.net
WWW: http://linux-ntfs.sf.net/ & http://www-stu.christs.cam.ac.uk/~aia21/