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H A Dnfs4state.c3d02fa29 Mon Sep 19 14:07:41 CDT 2011 J. Bruce Fields <bfields@redhat.com> nfsd4: fix open downgrade, again

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.

Cc: stable@kernel.org
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
3d02fa29 Mon Sep 19 14:07:41 CDT 2011 J. Bruce Fields <bfields@redhat.com> nfsd4: fix open downgrade, again

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.

Cc: stable@kernel.org
Signed-off-by: J. Bruce Fields <bfields@redhat.com>