Re: ext4 features

[Bill Davidsen]

Trond Myklebust wrote:

> On Sat, 2006-07-08 at 17:04 -0400, Bill Davidsen wrote:
>  
>
> > No, I didn't quite mean a manual touch, but a system call to "close and 
> > set time to high resolution" for files where time uniformity is 
> > important. Consider that in most cases the inodes times are set by the 
> > host machine clock, which I close the change reflects the fileserving 
> > host idea of time. If there were a call to close a file and set the 
> > times like touch, then that could be used, for both local and network files.
> >    
>
> Close should never update the time since that would be a violation of
> POSIX rules. Normally, an NFS client will never need to update the time:
> RPC calls like WRITE, READ and SETATTR will automatically do it for us
> whenever necessary.
>  

Let me restate this a third time in another way. What I suggest is a 
system call, NOT NAMED CLOSE, which does a close and touch. This was all 
blue sky discussion, new system calls are as valid as nanosecond 
resolution and syncronization between servers. Since this is a new call 
it is not specified by POSIX.

And Linus has already suggested that he would accept something similar, 
when I proposed something like "noatime" mounts, which only updated 
atime and mtime on open and close, to keep metadata relevant but not 
have the overhead of constant updates.

Actually, now that I have more free time I may revisit that idea.

--
bill davidsen <davidsen@xxxxxxx>
 CTO TMR Associates, Inc
 Doing interesting things with small computers since 1979

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