lightnvm: eliminate nvm_lun abstraction in mm

In order to naturally support multi-target instances on an Open-Channel
SSD, targets should own the LUNs they get blocks from and manage
provisioning internally. This is done in several steps.

Since targets own the LUNs the are instantiated on top of and manage the
free block list internally, there is no need for a LUN abstraction in
the media manager. LUNs are intrinsically managed as in the physical
layout (ch:0,lun:0, ..., ch:0,lun:n, ch:1,lun:0, ch:1,lun:n, ...,
ch:m,lun:0, ch:m,lun:n) and given to the targets based on the target
creation ioctl. This simplifies LUN management and clears the path for a
partition manager to sit directly underneath LightNVM targets.

Signed-off-by: Javier González <javier@cnexlabs.com>
Signed-off-by: Matias Bjørling <m@bjorling.me>
Signed-off-by: Jens Axboe <axboe@fb.com>

drivers/lightnvm/core.c

@@ -203,15 +203,19 @@ int nvm_set_bb_tbl(struct nvm_dev *dev, struct ppa_addr *ppas, int nr_ppas,
 }
 EXPORT_SYMBOL(nvm_set_bb_tbl);
 
-int nvm_submit_io(struct nvm_dev *dev, struct nvm_rq *rqd)
+int nvm_submit_io(struct nvm_tgt_dev *tgt_dev, struct nvm_rq *rqd)
 {
-	return dev->mt->submit_io(dev, rqd);
+	struct nvm_dev *dev = tgt_dev->parent;
+
+	return dev->mt->submit_io(tgt_dev, rqd);
 }
 EXPORT_SYMBOL(nvm_submit_io);
 
-int nvm_erase_blk(struct nvm_dev *dev, struct ppa_addr *p, int flags)
+int nvm_erase_blk(struct nvm_tgt_dev *tgt_dev, struct ppa_addr *p, int flags)
 {
-	return dev->mt->erase_blk(dev, p, flags);
+	struct nvm_dev *dev = tgt_dev->parent;
+
+	return dev->mt->erase_blk(tgt_dev, p, flags);
 }
 EXPORT_SYMBOL(nvm_erase_blk);
 
@@ -350,7 +354,7 @@ static int __nvm_submit_ppa(struct nvm_dev *dev, struct nvm_rq *rqd, int opcode,
 
 	nvm_generic_to_addr_mode(dev, rqd);
 
-	rqd->dev = dev;
+	rqd->dev = NULL;
 	rqd->opcode = opcode;
 	rqd->flags = flags;
 	rqd->bio = bio;