Date: Sun, 15 Mar 1998 17:06:14 -0600 From: Karl Denninger <karl@mcs.net> To: Terry Lambert <tlambert@primenet.com> Cc: hackers@FreeBSD.ORG Subject: Re: Odd problem we're seeing here Message-ID: <19980315170614.50631@mcs.net> In-Reply-To: <199803152212.PAA14399@usr06.primenet.com>; from Terry Lambert on Sun, Mar 15, 1998 at 10:12:59PM %2B0000 References: <199803152155.OAA13550@usr06.primenet.com> <199803152212.PAA14399@usr06.primenet.com>
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All I got out of turning on the NQNFS mode was a near-immediate hard system hang - no I/O, no nothing. Needless to say, that's no good :-) I don't know if my earlier mail got out or not, but wouldn't an effective workaround for the cache coherency problem be to flush the attribute cache on any flock(..., LOCK_UN) operation (either explicit or implied on file close)? -- -- Karl Denninger (karl@MCS.Net)| MCSNet - Serving Chicagoland and Wisconsin http://www.mcs.net/ | T1's from $600 monthly / All Lines K56Flex/DOV | NEW! Corporate ISDN Prices dropped by up to 50%! Voice: [+1 312 803-MCS1 x219]| EXCLUSIVE NEW FEATURE ON ALL PERSONAL ACCOUNTS Fax: [+1 312 803-4929] | *SPAMBLOCK* Technology now included at no cost On Sun, Mar 15, 1998 at 10:12:59PM +0000, Terry Lambert wrote: > > If you look at the code around the vn_read and vn_write, vs. the > > code around vn_rdwr, you will see a pattern begin to emerge. > > > > In all cases, when vn_read or vn_write is called, the vp is locked. > > I meant "unlocked". > > Right now, I am unsure of the lease code. When I say that I think > the vp should be locked, that's because all vp's should be locked > before they are dereferenced to make VOP calls. This is also why > vp locking should be done with a vn_lock() function which locks > the vp before it makes the VOP_LOCK call by dereferencing the vp > to get the FS specific function. This is also why the underlying > VOP_LOCK should be veto-based. > > Basically, if a vp is in the VOF layer (not necessarily just below > the VFS layer, at least until Michael Hancock's VOP_VRELE), the vp > should be locked. > > Period. > > This drastically simplifies a VFS consumer's view of the world. > > I do not think the lease code would actually survive being called > with a locked vp at this point because of nqnfs_lease_updatetime, > which traverses the mountlist. > > This is not something trivially fixable without a lot of controversial > code. > > Hence the punt. > > Is that enough information? > > Terry Lambert > terry@lambert.org > --- > Any opinions in this posting are my own and not those of my present > or previous employers. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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