[PATCH 3.2 055/102] NFSv4: Fix another bug in the close/open_downgrade code

[Ben Hutchings]

3.2.64-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx>

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@xxxxxxxxxxxxx>
Link: http://lkml.kernel.org/r/541AD7E5.8020409@xxxxxxxxxxxxx
Fixes: aee7af356e15 (NFSv4: Fix problems with close in the presence...)
Signed-off-by: Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx>
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
 fs/nfs/nfs4proc.c | 30 +++++++++++++++---------------
 1 file changed, 15 insertions(+), 15 deletions(-)

--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -2015,23 +2015,23 @@ static void nfs4_close_prepare(struct rp
 	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) {

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