|From:||Andrew Morton <akpm-AT-linux-foundation.org>|
|To:||Trond Myklebust <trond.myklebust-AT-fys.uio.no>|
|Subject:||Re: recent nfs change causes autofs regression|
|Date:||Thu, 30 Aug 2007 18:24:35 -0700|
|Cc:||Hua Zhong <hzhong-AT-gmail.com>, "'Linux Kernel Mailing List'" <linux-kernel-AT-vger.kernel.org>, "'Linus Torvalds'" <torvalds-AT-linux-foundation.org>|
On Thu, 30 Aug 2007 18:37:13 -0400 Trond Myklebust <email@example.com> wrote: > On Thu, 2007-08-30 at 14:07 -0700, Hua Zhong wrote: > > I am re-sending this after help from Ian and git-bisect. To me it's a > > show-stopper: I cannot find an acceptable workaround that I can implement. > > > > The problem: upgrading to 2.6.23-rc4 from 2.6.22 causes several autofs > > mounts to fail silently - they just not appear when they should. > > > > I believe it's caused by the NFS change that forces multiple mounts from > > different directories under the same server side filesystem to have the same > > mount options by default, otherwise it returns EBUSY. > > > > For example, if server has a filesystem /a, and it exports /a/x and /a/y > > (maybe with rw or ro), and a client must mount /a/x and /a/y with the same > > mount options now. > > Which is better than having it fail silently, or giving you a mount with > the wrong mount options. > > If you need to mount the same filesystem with incompatible mount options > on the same client, then there is a new mount option "nosharecache", > which enables it. > The new option is there in order to make it damned clear to sysadmins > that this is a dangerous thing to do: mounts which don't share the same > superblock also don't share the same data and attribute caches. Any file > or directory which appears in both mounts had better only be used by one > application at a time or be using an appropriate locking scheme. > If we're going to send a message to sysadmins, we shouldn't force them to go through a git bisection search and a lkml discussion to receive it! Is there at least some way in which the kernel can detect this situation and emit a friendly printk which guides people to a friendly document?
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