Date: Sat, 5 Apr 1997 17:40:31 +0100 (BST) From: Doug Rabson <dfr@nlsystems.com> To: Tor Egge <Tor.Egge@idi.ntnu.no> Cc: terry@lambert.org, dg@root.com, ponds!rivers@dg-rtp.dg.com, freebsd-hackers@freebsd.org Subject: Re: kern/3184: vnodes are used after they are freed. (dup alloc?) Message-ID: <Pine.BSF.3.95q.970405173829.8538J-100000@herring.nlsystems.com> In-Reply-To: <199704051629.SAA00567@pat.idt.unit.no>
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On Sat, 5 Apr 1997, Tor Egge wrote: > > > Proper locking on NFS will help against the crash I experienced, but > > > if the NFS server goes down at the wrong moment, a call to getnewvnode > > > may hang until the NFS server is back again. > > > > This will always be the case, right? > > > > Or do you mean the case where an attempt to vclean() a vnode is against > > an NFS vnode with the server down? > > When the first vnode on the so-called free list is a NFS vnode, where > VOP_INACTIVE is blocked (due to nfs_remove blocking when the NFS > server is down), that vnode cannot be reused for a long time (until > the nfs server is up again). > > When getnewvnode picks that vnode it waits for the lock to drain (in > vclean). if the routine that called getnewvnode is ffs_vget, the > ffs_inode_hash_lock is set while getnewvnode blocks. This has the > side effect that any further calls to ffs_vget will block. This might > block any creation of new files on local ufs file systems while the > NFS server is down. I know about this problem. Unfortunately the only way of fixing it is probably to keep private pools of vnodes for each filesystem (which Terry has been badgering me about for *years*). It might happen but it is a fair amount of work. For the moment, I will settle with a system which is stable, even it does hang when a server fails. -- Doug Rabson Mail: dfr@nlsystems.com Nonlinear Systems Ltd. Phone: +44 181 951 1891
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