On Tue, 20 Sep 2005, Jeff Moyer wrote:
> Hi, Ian, list,
>
> I have a bug filed against autofs when ghosting is enabled. The best way
> to describe the bug is to walk through the reproducer, I guess.
>
> Take the following maps, for example:
>
> auto.master
> /sbox auto.sbox
>
> auto.sbox:
> src segfault:/sbox/src/
>
> Let's say that there is a file, id3_0.12.orig.tar.gz, in segfault:/sbox/src/.
>
> To reproduce the problem, stop the nfs service on the server.
>
> On the client, do an 'ls /sbox/src/id3_012.orig.tar.gz'. This will fail,
> as well it should. However, if we look in the logs, we find this:
>
> automount[1182]: handle_packet_missing: token 1, name src
> automount[1182]: attempting to mount entry /sbox/src
> ...
> automount[1481]: mount(nfs): calling mkdir_path /sbox/src
> automount[1481]: mount(nfs): calling mount -t nfs -s-o
> tcp,intr,timeo=600,rsize=8192,wsize=8192,retrans=5 segfault:/sbox/src
> /sbox/src
> automount[1481]: >> mount: RPC: Program not registered
> automount[1481]: mount(nfs): add_bad_host: segfault:/sbox/src
> automount[1481]: mount(nfs): nfs: mount failure segfault:/sbox/src on
> /sbox/src
> automount[1481]: failed to mount /sbox/src
> ...
> automount[1182]: send_fail: token=1
> automount[1182]: handle_packet: type = 0
> automount[1182]: handle_packet_missing: token 2, name
> src/id3_0.12.orig.tar.gz
> automount[1182]: attempting to mount entry /sbox/src/id3_0.12.orig.tar.gz
>
> Noteworthy are these last two lines! Even though the mount failed, we are
> continuing the lookup. The culprit is here, in cached_lookup:
>
> if (!dentry->d_op->d_revalidate(dentry, flags) && !d_invalidate(dentry))
> {
> dput(dentry);
> dentry = NULL;
> }
>
> d_revalidate points to autofs4_revalidate, which calls try_to_fill_dentry,
> which will return a status of 0. Since ghosting is enabled,
> d_invalidate(dentry) will return -EBUSY, and so we return the dentry to
the
> caller, which then continues the lookup.
>
> Ian, I'm not really sure how we can address this issue without VFS
> changes. Any ideas?
>
I'm aware of this problem.
I'm not sure how to deal with it yet.
The case above is probably not that difficult to solve but if the last
component is a directory it's hard to work out it's a problem.
There's more information here than I've gathhered so far.
> Oh, also note that, once the nfs service is started up again on the server,
> the lookup of a specific file name will still fail! In this case, the
> daemon won't even be called.
I'll have to check this out.
It could be helpful.
>
> -Jeff
>
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