raid1: fix nr_pending leak in REQ_ATOMIC bad-block error path

In the Linux kernel, the following vulnerability has been resolved: raid1: fix nr_pending leak in REQ_ATOMIC bad-block error path In raid1_write_request(), each per-mirror loop iteration begins by incrementing rdev->nr_pending. If a REQ_ATOMIC write encounters a badblock within the requested range, the code jumps to err_handle without dropping the reference taken for the current mirror. err_handle's cleanup loop will only decrements for k < i and r1_bio->bios[k] is non-NULL. The current slot is therefore skipped, leaving its nr_pending reference leaked permanently. The reference prevents the rdev from ever being removed, since raid1_remove_conf() refuses to remove an rdev with nr_pending > 0. Fix this by calling rdev_dec_pending() before jumping to err_handle.