NFSv4: Fix another bug in the close/open_downgrade code

commit cd9288ffaea4359d5cfe2b8d264911506aed26a4 upstream.

James Drew reports another bug whereby the NFS client is now sending
an OPEN_DOWNGRADE in a situation where it should really have sent a
CLOSE: the client is opening the file for O_RDWR, but then trying to
do a downgrade to O_RDONLY, which is not allowed by the NFSv4 spec.

Reported-by: James Drews <drews@engr.wisc.edu>
Link: http://lkml.kernel.org/r/541AD7E5.8020409@engr.wisc.edu
Fixes: aee7af356e15 (NFSv4: Fix problems with close in the presence...)
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.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 c4a2a684a429de2c69d0835ccfb38fbcdb9b2f57..61a1303652dc86b92a5dd27f49a79f111db220c0 100644 (file)
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -2015,23 +2015,23 @@ static void nfs4_close_prepare(struct rpc_task *task, void *data)
        is_rdwr = test_bit(NFS_O_RDWR_STATE, &state->flags);
        is_rdonly = test_bit(NFS_O_RDONLY_STATE, &state->flags);
        is_wronly = test_bit(NFS_O_WRONLY_STATE, &state->flags);
-       /* Calculate the current open share mode */
-       calldata->arg.fmode = 0;
-       if (is_rdonly || is_rdwr)
-               calldata->arg.fmode |= FMODE_READ;
-       if (is_wronly || is_rdwr)
-               calldata->arg.fmode |= FMODE_WRITE;
        /* Calculate the change in open mode */
+       calldata->arg.fmode = 0;
        if (state->n_rdwr == 0) {
-               if (state->n_rdonly == 0) {
-                       call_close |= is_rdonly || is_rdwr;
-                       calldata->arg.fmode &= ~FMODE_READ;
-               }
-               if (state->n_wronly == 0) {
-                       call_close |= is_wronly || is_rdwr;
-                       calldata->arg.fmode &= ~FMODE_WRITE;
-               }
-       }
+               if (state->n_rdonly == 0)
+                       call_close |= is_rdonly;
+               else if (is_rdonly)
+                       calldata->arg.fmode |= FMODE_READ;
+               if (state->n_wronly == 0)
+                       call_close |= is_wronly;
+               else if (is_wronly)
+                       calldata->arg.fmode |= FMODE_WRITE;
+       } 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) {