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    SubjectRe: [PATCH 05/16] nfs: don't open in ->d_revalidate
    On Wed, 2012-03-28 at 22:24 +0200, Miklos Szeredi wrote:
    > From: Miklos Szeredi <>
    > NFSv4 can't do reliable opens in d_revalidate, since it cannot know whether a
    > mount needs to be followed or not. It does check d_mountpoint() on the dentry,
    > which can result in a weird error if the VFS found that the mount does not in
    > fact need to be followed, e.g.:
    > # mount --bind /mnt/nfs /mnt/nfs-clone
    > # echo something > /mnt/nfs/tmp/bar
    > # echo x > /tmp/file
    > # mount --bind /tmp/file /mnt/nfs-clone/tmp/bar
    > # cat /mnt/nfs/tmp/bar
    > cat: /mnt/nfs/tmp/bar: Not a directory
    > Which should, by any sane filesystem, result in "something" being printed.
    > So instead do the open in f_op->open() and in the unlikely case that the cached
    > dentry turned out to be invalid, drop the dentry and return ESTALE to let the
    > VFS retry.

    Just one comment. Would it now make sense for NFSv4 to just skip
    ->d_revalidate() if LOOKUP_OPEN is set, and LOOKUP_EXCL is not set? We
    will in any case be doing a revalidation in nfs4_file_open.

    Otherwise, the rest all looks good to me.

    Trond Myklebust
    Linux NFS client maintainer


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