NFS: Fix another OPEN_DOWNGRADE bug

commit e547f2628327fec6afd2e03b46f113f614cca05b upstream.

Olga Kornievskaia reports that the following test fails to trigger
an OPEN_DOWNGRADE on the wire, and only triggers the final CLOSE.

	fd0 = open(foo, RDRW)   -- should be open on the wire for "both"
	fd1 = open(foo, RDONLY)  -- should be open on the wire for "read"
	close(fd0) -- should trigger an open_downgrade
	read(fd1)
	close(fd1)

The issue is that we're missing a check for whether or not the current
state transitioned from an O_RDWR state as opposed to having transitioned
from a combination of O_RDONLY and O_WRONLY.

Reported-by: Olga Kornievskaia <aglo@umich.edu>
Fixes: cd9288ffaea4 ("NFSv4: Fix another bug in the close/open_downgrade code")
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index 609a951..9fc7998 100644 (file)
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -2025,12 +2025,11 @@ static void nfs4_close_prepare(struct rpc_task *task, void *data)
                        call_close |= is_wronly;
                else if (is_wronly)
                        calldata->arg.fmode |= FMODE_WRITE;
+               if (calldata->arg.fmode != (FMODE_READ|FMODE_WRITE))
+                       call_close |= is_rdwr;
        } else if (is_rdwr)
                calldata->arg.fmode |= FMODE_READ|FMODE_WRITE;
 
-       if (calldata->arg.fmode == 0)
-               call_close |= is_rdwr;
-
        spin_unlock(&state->owner->so_lock);
 
        if (!call_close) {