VFS: Make clone_mnt()/copy_tree()/collect_mounts() return errors

copy_tree() can theoretically fail in a case other than ENOMEM, but always
returns NULL which is interpreted by callers as -ENOMEM.  Change it to return
an explicit error.

Also change clone_mnt() for consistency and because union mounts will add new
error cases.

Thanks to Andreas Gruenbacher <agruen@suse.de> for a bug fix.
[AV: folded braino fix by Dan Carpenter]

Original-author: Valerie Aurora <vaurora@redhat.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Cc: Valerie Aurora <valerie.aurora@gmail.com>
Cc: Andreas Gruenbacher <agruen@suse.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 3 insertions, 2 deletions

diff --git a/fs/pnode.c b/fs/pnode.c
index bed378db0758..3e000a51ac0d 100644
--- a/fs/pnode.c
+++ b/fs/pnode.c
@@ -237,8 +237,9 @@ int propagate_mnt(struct mount *dest_mnt, struct dentry *dest_dentry,
 
                 source =  get_source(m, prev_dest_mnt, prev_src_mnt, &type);
 
-                if (!(child = copy_tree(source, source->mnt.mnt_root, type))) {
-                        ret = -ENOMEM;
+                child = copy_tree(source, source->mnt.mnt_root, type);
+                if (IS_ERR(child)) {
+                        ret = PTR_ERR(child);
                         list_splice(tree_list, tmp_list.prev);
                         goto out;
                 }