nfsd4: fix open downgrade, again
authorJ. Bruce Fields <bfields@redhat.com>
Mon, 19 Sep 2011 19:07:41 +0000 (15:07 -0400)
committerGreg Kroah-Hartman <gregkh@suse.de>
Fri, 11 Nov 2011 17:43:16 +0000 (09:43 -0800)
commit68251a1702ee17bd375a5b7907ce8794d7dadf6d
tree9e7ee1937016aa1d4eaf9be5991c06751671a22e
parentfdbc365c5c59f7b8ce619299097225e556e4f0f7
nfsd4: fix open downgrade, again

commit 3d02fa29dec920c597dd7b7db608a4bc71f088ce upstream.

Yet another open-management regression:

- nfs4_file_downgrade() doesn't remove the BOTH access bit on
  downgrade, so the server's idea of the stateid's access gets
  out of sync with the client's.  If we want to keep an O_RDWR
  open in this case, we should do that in the file_put_access
  logic rather than here.
- We forgot to convert v4 access to an open mode here.

This logic has proven too hard to get right.  In the future we may
consider:
- reexamining the lock/openowner relationship (locks probably
  don't really need to take their own references here).
- adding open upgrade/downgrade support to the vfs.
- removing the atomic operations.  They're redundant as long as
  this is all under some other lock.

Also, maybe some kind of additional static checking would help catch
O_/NFS4_SHARE_ACCESS confusion.

Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
fs/nfsd/nfs4state.c