NFSv4: Fix open(O_TRUNC) and ftruncate() error handling

If the file wasn't opened for writing, then truncate and ftruncate
need to report the appropriate errors.

Reported-by: Miklos Szeredi <miklos@szeredi.hu>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Cc: stable@vger.kernel.org

2 files changed, 14 insertions, 5 deletions

diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c
index 4aaf0316d76a..8789210c6905 100644
--- a/fs/nfs/dir.c
+++ b/fs/nfs/dir.c
@@ -1429,7 +1429,7 @@ static struct dentry *nfs_atomic_lookup(struct inode *dir, struct dentry *dentry
         }
 
         open_flags = nd->intent.open.flags;
-        attr.ia_valid = 0;
+        attr.ia_valid = ATTR_OPEN;
 
         ctx = create_nfs_open_context(dentry, open_flags);
         res = ERR_CAST(ctx);
@@ -1536,7 +1536,7 @@ static int nfs_open_revalidate(struct dentry *dentry, struct nameidata *nd)
         if (IS_ERR(ctx))
                 goto out;
 
-        attr.ia_valid = 0;
+        attr.ia_valid = ATTR_OPEN;
         if (openflags & O_TRUNC) {
                 attr.ia_valid |= ATTR_SIZE;
                 attr.ia_size = 0;
diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index ba837d977a1a..f875cf305237 100644
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -1954,10 +1954,19 @@ static int nfs4_do_setattr(struct inode *inode, struct rpc_cred *cred,
         };
         int err;
         do {
-                err = nfs4_handle_exception(server,
-                                _nfs4_do_setattr(inode, cred, fattr, sattr, state),
-                                &exception);
+                err = _nfs4_do_setattr(inode, cred, fattr, sattr, state);
+                switch (err) {
+                case -NFS4ERR_OPENMODE:
+                        if (state && !(state->state & FMODE_WRITE)) {
+                                err = -EBADF;
+                                if (sattr->ia_valid & ATTR_OPEN)
+                                        err = -EACCES;
+                                goto out;
+                        }
+                }
+                err = nfs4_handle_exception(server, err, &exception);
         } while (exception.retry);
+out:
         return err;
 }