NFSD: Fix handling of oversized NFSv4 COMPOUND requests

NFSD: Fix handling of oversized NFSv4 COMPOUND requests

[ Upstream commit 7518a3dc5ea249d4112156ce71b8b184eb786151 ]

If an NFS server returns NFS4ERR_RESOURCE on the first operation in
an NFSv4 COMPOUND, there's no way for a client to know where the
problem is and then simplify the compound to make forward progress.

So instead, make NFSD process as many operations in an oversized
COMPOUND as it can and then return NFS4ERR_RESOURCE on the first
operation it did not process.

pynfs NFSv4.0 COMP6 exercises this case, but checks only for the
COMPOUND status code, not whether the server has processed any
of the operations.

pynfs NFSv4.1 SEQ6 and SEQ7 exercise the NFSv4.1 case, which detects
too many operations per COMPOUND by checking against the limits
negotiated when the session was created.

Suggested-by: Bruce Fields <bfields@fieldses.org>
Fixes: 0078117c6d91 ("nfsd: return RESOURCE not GARBAGE_ARGS on too many ops")
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>