lightnvm: pblk: move ring buffer alloc/free rb init

pblk's read/write buffer currently takes a buffer and its size and uses
it to create the metadata around it to use it as a ring buffer. This
puts the responsibility of allocating/freeing ring buffer memory on the
ring buffer user. Instead, move it inside of the ring buffer helpers
(pblk-rb.c). This simplifies creation/destruction routines.

Signed-off-by: Javier González <javier@cnexlabs.com>
Signed-off-by: Matias Bjørling <mb@lightnvm.io>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/drivers/lightnvm/pblk.h b/drivers/lightnvm/pblk.h
index 7660811..0f98ea2 100644
--- a/drivers/lightnvm/pblk.h
+++ b/drivers/lightnvm/pblk.h
@@ -734,10 +734,7 @@ struct pblk_line_ws {
 /*
  * pblk ring buffer operations
  */
-int pblk_rb_init(struct pblk_rb *rb, struct pblk_rb_entry *rb_entry_base,
-		 unsigned int power_size, unsigned int power_seg_sz);
-unsigned int pblk_rb_calculate_size(unsigned int nr_entries);
-void *pblk_rb_entries_ref(struct pblk_rb *rb);
+int pblk_rb_init(struct pblk_rb *rb, unsigned int size, unsigned int seg_sz);
 int pblk_rb_may_write_user(struct pblk_rb *rb, struct bio *bio,
 			   unsigned int nr_entries, unsigned int *pos);
 int pblk_rb_may_write_gc(struct pblk_rb *rb, unsigned int nr_entries,
@@ -771,7 +768,7 @@ unsigned int pblk_rb_wrap_pos(struct pblk_rb *rb, unsigned int pos);
 
 int pblk_rb_tear_down_check(struct pblk_rb *rb);
 int pblk_rb_pos_oob(struct pblk_rb *rb, u64 pos);
-void pblk_rb_data_free(struct pblk_rb *rb);
+void pblk_rb_free(struct pblk_rb *rb);
 ssize_t pblk_rb_sysfs(struct pblk_rb *rb, char *buf);
 
 /*