Messages in this thread | | | Date | Wed, 23 Apr 1997 16:59:01 -0500 (EST) | From | James Mastros <> | Subject | Re: Volume management on Linux with the ext2fs. |
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On 23 Apr 1997, Stefan Monnier wrote: > > Agreed. Actually it recently occured to me that the CacheFS that I'd like Linux > to support could be (to some point) implemented as an extension of e2fs: > create a new type of link (let's call it a copylink). When it is accessed, it > gets replaced by what it points to (and if it was a directory, the directory is > not copied recursively but filled up with copylinks, of course). The thing > could later be improved so as to support copying the inode of a remote file > without the file itself, or even allow to have only some blocks of a remote > file be copied locally. Also some way to "flush the cache" would be needed > (or at least some way to rollback copies of files into copylinks so as to > recover disk space when needed or so as to update remote files that have > changed) > > > Stefan >
Implementing copy-on-write for FSes like for memory, basicaly. I thought of somthing like that when I first heard of copy-on-write; but I wasn't good enough of a kernel hacker to mention it. I'm still not good enough of a kernel hacker to even think about doing it, but atleast I'm confident enough to mention it.
The easyest way to implement it would likely be as a hard link (because it would act like one on read), but with a flag to be checked during writes. Fortinataly, it looks like there is plenty of free space in the umode feild, so we should be able to implement this at a VFS level.
Quite likely wrong, -=- James Mastros
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