NFS: Revert "NFS: Move the flock open mode check into nfs_flock()"

Commit e12937279c8b "NFS: Move the flock open mode check into nfs_flock()"
changed NFSv3 behavior for flock() such that the open mode must match the
lock type, however that requirement shouldn't be enforced for flock().

Signed-off-by: Benjamin Coddington <bcodding@redhat.com>
Cc: stable@vger.kernel.org # v4.12
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>

2 files changed, 16 insertions, 16 deletions

diff --git a/fs/nfs/file.c b/fs/nfs/file.c
index 0214dd1e1060..81cca49a8375 100644
--- a/fs/nfs/file.c
+++ b/fs/nfs/file.c
@@ -829,23 +829,9 @@ int nfs_flock(struct file *filp, int cmd, struct file_lock *fl)
         if (NFS_SERVER(inode)->flags & NFS_MOUNT_LOCAL_FLOCK)
                 is_local = 1;
 
-        /*
-         * VFS doesn't require the open mode to match a flock() lock's type.
-         * NFS, however, may simulate flock() locking with posix locking which
-         * requires the open mode to match the lock type.
-         */
-        switch (fl->fl_type) {
-        case F_UNLCK:
+        /* We're simulating flock() locks using posix locks on the server */
+        if (fl->fl_type == F_UNLCK)
                 return do_unlk(filp, cmd, fl, is_local);
-        case F_RDLCK:
-                if (!(filp->f_mode & FMODE_READ))
-                        return -EBADF;
-                break;
-        case F_WRLCK:
-                if (!(filp->f_mode & FMODE_WRITE))
-                        return -EBADF;
-        }
-
         return do_setlk(filp, cmd, fl, is_local);
 }
 EXPORT_SYMBOL_GPL(nfs_flock);
diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index 6b23a032ee1e..56fa5a16e097 100644
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -6709,6 +6709,20 @@ nfs4_proc_lock(struct file *filp, int cmd, struct file_lock *request)
             !test_bit(NFS_STATE_POSIX_LOCKS, &state->flags))
                 return -ENOLCK;
 
+        /*
+         * Don't rely on the VFS having checked the file open mode,
+         * since it won't do this for flock() locks.
+         */
+        switch (request->fl_type) {
+        case F_RDLCK:
+                if (!(filp->f_mode & FMODE_READ))
+                        return -EBADF;
+                break;
+        case F_WRLCK:
+                if (!(filp->f_mode & FMODE_WRITE))
+                        return -EBADF;
+        }
+
         status = nfs4_set_lock_state(state, request);
         if (status != 0)
                 return status;