[PATCH 3.14 19/53] NFS: Fix another OPEN_DOWNGRADE bug

Greg Kroah-Hartman
2016-07-25T22:46:43Z

From: Trond Myklebust <trond.myklebust@primarydata.com>

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
fs/nfs/nfs4proc.c | 5 ++---
1 file changed, 2 insertions(+), 3 deletions(-)

--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -2583,12 +2583,11 @@ static void nfs4_close_prepare(struct rp
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;
-
if (!nfs4_valid_open_stateid(state))
call_close = 0;
spin_unlock(&state->owner->so_lock);