[lkml]   [2009]   [Feb]   [23]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRe: [RFC 2/8] Aufs2: structure
> The struct of a xino file is simple, just a sequence of aufs inode
> numbers which is indexed by the lower inode number.
> In the above sample, assume the inode number of /ro/fileA is i111 and
> aufs assigns the inode number i999 for fileA. Then aufs writes 999 as
> 4(8) bytes at 111 * 4(8) bytes offset in the xino file.

I think it is worth mentioning that the xino file, if I understand it correctly, is a 'sparse file', that means it is full of 'holes' and doesn't consume as much disk space as it might appear.

In my opinion, the current xino-file approach is not much usable on filesystems which do not support sparse files (for example, if you wish to union two vfats), since some 'seeks' would probably write a lot of nulls. But I am not any kernel developer so I don't even know if there exists any filesystem which would be unable to support sparse files (except the mentioned VFAT, of course).

Tomas M

 \ /
  Last update: 2009-02-23 10:33    [W:0.117 / U:19.172 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site