Re: ext4 features

Bill Davidsen
2006-07-10T22:28:23Z

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@tmr.com>
CTO TMR Associates, Inc
Doing interesting things with small computers since 1979