Date: Mon, 22 Nov 2010 21:01:05 -0500 (EST) From: Rick Macklem <rmacklem@uoguelph.ca> To: John Baldwin <jhb@freebsd.org> Cc: freebsd-fs@freebsd.org, Ivan Voras <ivoras@freebsd.org> Subject: Re: preferred kernel upcall method to master nfsd Message-ID: <1793929802.495869.1290477665351.JavaMail.root@erie.cs.uoguelph.ca> In-Reply-To: <201011221629.27166.jhb@freebsd.org>
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> > nfsd is a user process. I suspect that when it receives a signal it > falls out of > nfssvc() with EINTR and handles saving the restart file in userland. > Is that close > to the process Rick or does you need to send a signal between threads > that are > exclusively within the kernel? > Yep, the kernel nfsd thread needs to tell the userland master nfsd to make a backup copy of the stable restart file now. Doing it with signals, the kernel code would post a signal (SIGUSR2 ?) to the master nfsd (which is normally in userland). The master nfsd would simply have a signal handler for SIGUSR2 that would copy the file (it's pretty small) to a backup copy. At least that's how I would think I could code it. I haven't actually tried it? My question was mostly if there was a preferred/better way for the kernel code to tell the userland master nfsd to copy the file? rick
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