[PATCH 0/7 RFC] fixes for vfs_lookup_open, and integration with nfsd

[NeilBrown <neilb@ownmail.net>]

I've been looking at the problems Chuck and Jeff found with my
vfs_lookup_open() work for opening files in nfsd and think the following
patches address the issues.

I have labeled this an RFC because:
1/ Patch 2/7 changes user-visible behaviour - in a good way I think.
   Currently O_NONBLOCK avoids waiting for a leases but doesn't
   avoid waiting for a directory delegation.  I think it should do both. 
2/ vfs_lookup_open() is changed to update the 'dentry' in the path arg
   to report what was found.  On success this is identical to the
   returned file->f_path.dentry. On -EFTYPE failure it is useful
   to report the actual type to the NFS client as required.

As an aside - what would people think of changing ->atomic_open
functions to *not* return -EFTYPE.  If they find a non-regular file they
should use finish_no_open() and let the caller decide if a non-regular
is an error.  ->atomic_open can still honour O_DIRECTORY if a network
filesystem does that some special way, but if it find a non-regular when
O_DIRECTORY wasn't requested, it is best to report what it found and let
others deal with it.  As it is we need an extra d_lookup() in
vfs_lookup_open() to find the dentry that ->atomic_open refused to
return.

Or maybe we shouldn't pass __O_REGULAR because that only affects "open",
and lookup_open() doesn't even try to open non-regular files.

I'm keen to read your thoughts on the above.

Thanks,
NeilBrown


 [PATCH 1/7] vfs: add some allowed open flags to vfs_lookup_open()
 [PATCH 2/7] vfs: O_NONBLOCK|O_CREAT open shouldn't wait for directory
 [PATCH 3/7] vfs: vfs_lookup_open() should only return -EFTYPE for
 [PATCH 4/7] vfs: change vfs_lookup_open() to return found dentry in
 [PATCH 5/7] nfsd: switch NFS4 OPEN to use vfs_lookup_open()
 [PATCH 6/7] nfsd: nfsd_check_obj_isreg() to use nfs error codes.
 [PATCH 7/7] nfsd: use vfs_lookup_open() for non-creating open