Messages in this thread | | | From | "Myklebust, Trond" <> | Subject | Re: [PATCH 05/16] nfs: don't open in ->d_revalidate | Date | Wed, 28 Mar 2012 21:45:18 +0000 |
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On Wed, 2012-03-28 at 22:24 +0200, Miklos Szeredi wrote: > From: Miklos Szeredi <mszeredi@suse.cz> > > 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
NetApp Trond.Myklebust@netapp.com www.netapp.com
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