Date: Sun, 21 Mar 2004 02:31:08 -0800
From: Frank Cusack <fcusack@fcusack.com>
To: lkml <linux-kernel@vger.kernel.org>
Subject: Does Linux sync(2) wait?
Message-ID: <20040321023107.A31553@google.com>
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Looking at 2.4 and 2.6 sources, Linux does appear to wait before returning.
I'm especially interested if NFS data is sent to the server.  (I want to
be able to take a stable snapshot of a netapp volume.)

But on my RHL 9 system, I have 3 different man pages and an info page,
all of which say something different.

sync(2) says:

       According  to the standard specification (e.g., SVID), sync() schedules
       the writes, but may return before the actual writing is done.  However,
       since  version  1.3.20  Linux does actually wait. 

sync(8) says:

       On Linux, sync is only guaranteed to  schedule  the  dirty  blocks  for
       writing;  it  can  actually take a short time before all the blocks are
       finally written.  

sync(1) is in the middle and doesn't really say anything, it refers to
the info page which also isn't specific.

/fc
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