Date: Wed, 25 May 2005 13:55:41 -0400 From: David Andersen <dga+@cs.cmu.edu> To: David Andersen <dga+@cs.cmu.edu> Cc: freebsd-hackers@freebsd.org Subject: Re: Opening raw disk while mounted in 5.x? Message-ID: <dbc4f09fbd976f0fb0e10c324704c164@cs.cmu.edu> In-Reply-To: <f7355c61ebfc40d096adb2c862cacf3b@cs.cmu.edu> References: <f7355c61ebfc40d096adb2c862cacf3b@cs.cmu.edu>
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To answer my own question - this appears to be done in the geom subsystem now. It can be avoided by enabling the magic foot-shooting debug flag: sysctl -w kern.geom.debugflags=16 if you're inclined to shoot yourself in the foot. -Dave On May 25, 2005, at 1:10 PM, David Andersen wrote: > Hoping someone knows the quick answer to this - in 4.x, it was > possible to open /dev/ad0 while a filesystem one one of its slices was > mounted. This no longer appears possible under 5.x. Could someone > point me to the spot in the code where I'd need to disable a > permissions check (or a sysctl, or anything) to permit this behavior > again? > > (The context: mounting slice 2 of a disk and using it to store a > compressed filesystem image. Then opening the primary disk device to > directly write the filesystem image onto slice 1. The kernel seems to > muck with the write calls if we try to do the write onto slice 1 > instead of the raw disk). This is using the very cool > imagezip/imageunzip utilities from the Utah Emulab project. > > Thanks! > > -Dave >
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