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    SubjectRe: autofs4 looks up wrong path element when ghosting is enabled
    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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