lightnvm: pblk: remove spinlock when freeing line metadata

Lockdep complains about being in atomic context while freeing line
metadata - and rightly so as we take a spinlock and end up calling
vfree that might sleep(in pblk_mfree).

There is no need for holding the line manager free_lock while
freeing line metadata as the pipeline as stopped, so remove the lock.

Fixes: 588726d3 ("lightnvm: pblk: fail gracefully on irrec. error")
Signed-off-by: Hans Holmberg <hans.holmberg@cnexlabs.com>
Signed-off-by: Matias Bjørling <m@bjorling.me>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

drivers/lightnvm/pblk-init.c

@@ -393,13 +393,11 @@ static void pblk_line_meta_free(struct pblk *pblk)
 	kfree(l_mg->bb_aux);
 	kfree(l_mg->vsc_list);
 
-	spin_lock(&l_mg->free_lock);
 	for (i = 0; i < PBLK_DATA_LINES; i++) {
 		kfree(l_mg->sline_meta[i]);
 		pblk_mfree(l_mg->eline_meta[i]->buf, l_mg->emeta_alloc_type);
 		kfree(l_mg->eline_meta[i]);
 	}
-	spin_unlock(&l_mg->free_lock);
 
 	kfree(pblk->lines);
 }