tree 020ae5b00a03fbf69b1624ca2cbcb2d95f31b4f7
parent 74918f937d9896aa2910cfe81f06499abd1dba59
author Trond Myklebust <trond.myklebust@primarydata.com> 1438877190 -0400
committer Trond Myklebust <trond.myklebust@primarydata.com> 1439836641 -0500

NFS: Don't let the ctime override attribute barriers.

Chuck reports seeing cases where a GETATTR that happens to race
with an asynchronous WRITE is overriding the file size, despite
the attribute barrier being set by the writeback code.

The culprit turns out to be the check in nfs_ctime_need_update(),
which sees that the ctime is newer than the cached ctime, and
assumes that it is safe to override the attribute barrier.
This patch removes that override, and ensures that attribute
barriers are always respected.

Reported-by: Chuck Lever <chuck.lever@oracle.com>
Fixes: a08a8cd375db9 ("NFS: Add attribute update barriers to NFS writebacks")
Cc: stable@vger.kernel.org # v4.0+
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>