2005-12-07 20:39:34

by Kenny Simpson

Subject: An nfs question ftruncate vs. pwrite

When a file that is opened with normal flags (O_RDWR|O_CREAT|O_TRUNC|O_LARGEFILE) is on NFS, and
it is exteded via ftruncate, the new expty pages get read back from the server before the system
call returns:
(from strace -T):
ftruncate64(3, 41943040) = 0 <0.063866>


-Kenny




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2005-12-07 21:12:27

by Peter Staubach

Subject: Re: An nfs question ftruncate vs. pwrite

Kenny Simpson wrote:

>When a file that is opened with normal flags (O_RDWR|O_CREAT|O_TRUNC|O_LARGEFILE) is on NFS, and
>it is exteded via ftruncate, the new expty pages get read back from the server before the system
>call returns:
> (from strace -T):
>ftruncate64(3, 41943040) = 0 <0.063866>
>

Is there a question in there?

If the question is whether the new empty pages get read in from the
server before the ftruncate system call returns, then no, they do not.
They get read in from the server as required in the normal course of
future operations.

Thanx...

ps