ovl: fix dentry reference leak
In ovl_copy_up_locked(), newdentry is leaked if the function exits through out_cleanup as this just to out after calling ovl_cleanup() - which doesn't actually release the ref on newdentry. The out_cleanup segment should instead exit through out2 as certainly newdentry leaks - and possibly upper does also, though this isn't caught given the catch of newdentry. Without this fix, something like the following is seen: BUG: Dentry ffff880023e9eb20{i=f861,n=#ffff880023e82d90} still in use (1) [unmount of tmpfs tmpfs] BUG: Dentry ffff880023ece640{i=0,n=bigfile} still in use (1) [unmount of tmpfs tmpfs] when unmounting the upper layer after an error occurred in copyup. An error can be induced by creating a big file in a lower layer with something like: dd if=/dev/zero of=/lower/a/bigfile bs=65536 count=1 seek=$((0xf000)) to create a large file (4.1G). Overlay an upper layer that is too small (on tmpfs might do) and then induce a copy up by opening it writably. Reported-by: Ulrich Obergfell <uobergfe@redhat.com> Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Miklos Szeredi <miklos@szeredi.hu> Cc: <stable@vger.kernel.org> # v3.18+
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