Date: Mon, 26 Apr 1999 12:12:05 -0400 (EDT) From: Luoqi Chen <luoqi@watermarkgroup.com> To: freebsd-hackers@FreeBSD.ORG, zzhang@cs.binghamton.edu Subject: Re: Logical block number caching Message-ID: <199904261612.MAA15096@lor.watermarkgroup.com>
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> The 4.4BSD book says the following on page 227: > > The drawback to using a *logical* address cache is that it is difficult to > detect aliases for a block belonging to a local file and the same block > accessed through the block device disk whose logical block address is the > same as the physical block address. The kernel handles these aliases by > administratively preventing them from occuring. The kernel does not allow > the block device for a partition to be opened while that partition is > mounted and vice versa. > > Is this the same situation with FreeBSD 3.1? I have tried to find where in > the source code this gets handled without luck. I hope someone will tell > me whether FreeBSD uses the same strategy and which routines handle this. > > Any help is appreciated. > > -------------------------------------------------- > Zhihui Zhang. Please visit http://www.freebsd.org > -------------------------------------------------- > I believe it still applies to FreeBSD. The code that prevents mounted block device from being opened is in miscfs/specfs/spec_vnops.c -lq To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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