From owner-freebsd-hackers@freebsd.org  Fri Mar  3 06:13:55 2017
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From: "Rodney W. Grimes" <freebsd-rwg@pdx.rh.CN85.dnsmgr.net>
Message-Id: <201703030613.v236DqUN067774@pdx.rh.CN85.dnsmgr.net>
Subject: Re: effect of strip(1) on du(1)
In-Reply-To: <CAGHfRMCVQdD4uULOPZsNxrrEZ+NAtJ6f1qMdSc8xtCHmwEfYMg@mail.gmail.com>
To: Ngie Cooper <yaneurabeya@gmail.com>
Date: Thu, 2 Mar 2017 22:13:52 -0800 (PST)
CC: Subbsd <subbsd@gmail.com>, Peter Jeremy <peter@rulingia.com>,
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[ Charset UTF-8 unsupported, converting... ]
> On Thu, Mar 2, 2017 at 4:31 PM, Rodney W. Grimes
> <freebsd-rwg@pdx.rh.cn85.dnsmgr.net> wrote:
> ...
> > Even if that is the case file system cache effects should NOT be
> > visible to a userland process.   This is NOT as if your running
> > 2 different processing beating on a file.  Your test cases are
> > serialially syncronous shell invoked commands seperated with
> > && the results should be exact and predictable.
> >
> > When strip returns the operation from the userland perspecive
> > is completed and any and all processeses started after that
> > should have the view of the completed strip command.
> >
> > This IS a bug.
> 
> Would the same statement necessarily apply if the filesystem was
> writing things asynchronously to the backing storage?

Caching should^h^h^h^hshall be transparent to a userland process.
Are you actually advocating that a userland process should
be able to see that zfs is write caching meta data?

The strip(1) command has completed and exited, pola dictates
that anything I asked strip(1) to do be reflected in all commands
or system calls executed after it.

Anything else would be a bug.

> Thanks,
> -Ngie

-- 
Rod Grimes                                                 rgrimes@freebsd.org