[PATCH v8 2/5] lightnvm: Hybrid Open-Channel SSD block manager

[Matias BjÃrling]

The host implementation for Open-Channel SSDs is divided into block
management and targets. This patch implements a basic block manager
hybrid open-channel SSDs. On top of the block manager, a target can
be initialized.

Signed-off-by: Matias BjÃrling <m@xxxxxxxxxxx>
---
 drivers/lightnvm/Kconfig  |   7 +
 drivers/lightnvm/Makefile |   1 +
 drivers/lightnvm/bm_hb.c  | 372 ++++++++++++++++++++++++++++++++++++++++++++++
 drivers/lightnvm/bm_hb.h  |  46 ++++++
 4 files changed, 426 insertions(+)
 create mode 100644 drivers/lightnvm/bm_hb.c
 create mode 100644 drivers/lightnvm/bm_hb.h

diff --git a/drivers/lightnvm/Kconfig b/drivers/lightnvm/Kconfig
index d4f309f..15e507a 100644
--- a/drivers/lightnvm/Kconfig
+++ b/drivers/lightnvm/Kconfig
@@ -25,4 +25,11 @@ config NVM_DEBUG
 
 	It is required to create/remove targets without IOCTLs.
 
+config NVM_BM_HB
+	tristate "Block manager for Hybrid Open-Channel SSD"
+	---help---
+	Block manager for SSDs that offload block management off to the device,
+	while keeping data placement and garbage collection decisions on the
+	host.
+
 endif # NVM
diff --git a/drivers/lightnvm/Makefile b/drivers/lightnvm/Makefile
index 38185e9..5228f83 100644
--- a/drivers/lightnvm/Makefile
+++ b/drivers/lightnvm/Makefile
@@ -3,3 +3,4 @@
 #
 
 obj-$(CONFIG_NVM)		:= core.o
+obj-$(CONFIG_NVM_BM_HB) 	+= bm_hb.o
diff --git a/drivers/lightnvm/bm_hb.c b/drivers/lightnvm/bm_hb.c
new file mode 100644
index 0000000..22c6db7
--- /dev/null
+++ b/drivers/lightnvm/bm_hb.c
@@ -0,0 +1,372 @@
+/*
+ * Copyright (C) 2015 Matias Bjorling <m@xxxxxxxxxxx>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License version
+ * 2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; see the file COPYING.  If not, write to
+ * the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139,
+ * USA.
+ *
+ * Implementation of a block manager for hybrid open-channel SSD.
+ */
+
+#include "bm_hb.h"
+
+static void hb_blocks_free(struct nvm_dev *dev)
+{
+	struct bm_hb *bm = dev->bmp;
+	struct bm_lun *lun;
+	int i;
+
+	bm_for_each_lun(bm, lun, i) {
+		if (!lun->vlun.blocks)
+			break;
+		vfree(lun->vlun.blocks);
+	}
+}
+
+static void hb_luns_free(struct nvm_dev *dev)
+{
+	struct bm_hb *bm = dev->bmp;
+
+	kfree(bm->luns);
+}
+
+static int hb_luns_init(struct nvm_dev *dev, struct bm_hb *bm)
+{
+	struct bm_lun *lun;
+	struct nvm_id_chnl *chnl;
+	int i;
+
+	bm->luns = kcalloc(bm->nr_luns, sizeof(struct bm_lun), GFP_KERNEL);
+	if (!bm->luns)
+		return -ENOMEM;
+
+	bm_for_each_lun(bm, lun, i) {
+		chnl = &dev->identity.chnls[i];
+		pr_info("bm_hb: p %u qsize %u gr %u ge %u begin %llu end %llu\n",
+			i, chnl->queue_size, chnl->gran_read, chnl->gran_erase,
+			chnl->laddr_begin, chnl->laddr_end);
+
+		spin_lock_init(&lun->vlun.lock);
+
+		INIT_LIST_HEAD(&lun->free_list);
+		INIT_LIST_HEAD(&lun->used_list);
+		INIT_LIST_HEAD(&lun->bb_list);
+
+		lun->vlun.id = i;
+		lun->chnl = chnl;
+		lun->reserved_blocks = 2; /* for GC only */
+		lun->vlun.nr_blocks =
+				(chnl->laddr_end - chnl->laddr_begin + 1) /
+				(chnl->gran_erase / chnl->gran_read);
+		lun->vlun.nr_free_blocks = lun->vlun.nr_blocks;
+		lun->vlun.nr_pages_per_blk =
+				chnl->gran_erase / chnl->gran_write *
+					(chnl->gran_write / dev->sector_size);
+
+		if (lun->vlun.nr_pages_per_blk > dev->max_pages_per_blk)
+			dev->max_pages_per_blk = lun->vlun.nr_pages_per_blk;
+
+		dev->total_pages += lun->vlun.nr_blocks *
+						lun->vlun.nr_pages_per_blk;
+		dev->total_blocks += lun->vlun.nr_blocks;
+	}
+
+	return 0;
+}
+
+static int hb_block_bb(u32 lun_id, void *bb_bitmap, unsigned int nr_blocks,
+								void *private)
+{
+	struct bm_hb *bm = private;
+	struct bm_lun *lun = &bm->luns[lun_id];
+	struct nvm_block *block;
+	int i;
+
+	if (unlikely(bitmap_empty(bb_bitmap, nr_blocks)))
+		return 0;
+
+	i = -1;
+	while ((i = find_next_bit(bb_bitmap, nr_blocks, i + 1)) <
+			nr_blocks) {
+		block = &lun->vlun.blocks[i];
+		if (!block) {
+			pr_err("bm_hb: BB data is out of bounds!\n");
+			return -EINVAL;
+		}
+		list_move_tail(&block->list, &lun->bb_list);
+	}
+
+	return 0;
+}
+
+static int hb_block_map(u64 slba, u64 nlb, u64 *entries, void *private)
+{
+	struct nvm_dev *dev = private;
+	struct bm_hb *bm = dev->bmp;
+	sector_t max_pages = dev->total_pages * (dev->sector_size >> 9);
+	u64 elba = slba + nlb;
+	struct bm_lun *lun;
+	struct nvm_block *blk;
+	sector_t total_pgs_per_lun = /* each lun have the same configuration */
+		 bm->luns[0].vlun.nr_blocks * bm->luns[0].vlun.nr_pages_per_blk;
+	u64 i;
+	int lun_id;
+
+	if (unlikely(elba > dev->total_pages)) {
+		pr_err("bm_hb: L2P data from device is out of bounds!\n");
+		return -EINVAL;
+	}
+
+	for (i = 0; i < nlb; i++) {
+		u64 pba = le64_to_cpu(entries[i]);
+
+		if (unlikely(pba >= max_pages && pba != U64_MAX)) {
+			pr_err("bm_hb: L2P data entry is out of bounds!\n");
+			return -EINVAL;
+		}
+
+		/* Address zero is a special one. The first page on a disk is
+		 * protected. As it often holds internal device boot
+		 * information. */
+		if (!pba)
+			continue;
+
+		/* resolve block from physical address */
+		lun_id = pba / total_pgs_per_lun;
+		lun = &bm->luns[lun_id];
+
+		/* Calculate block offset into lun */
+		pba = pba - (total_pgs_per_lun * lun_id);
+		blk = &lun->vlun.blocks[pba / lun->vlun.nr_pages_per_blk];
+
+		if (!blk->type) {
+			/* at this point, we don't know anything about the
+			 * block. It's up to the FTL on top to re-etablish the
+			 * block state */
+			list_move_tail(&blk->list, &lun->used_list);
+			blk->type = 1;
+			lun->vlun.nr_free_blocks--;
+		}
+	}
+
+	return 0;
+}
+
+static int hb_blocks_init(struct nvm_dev *dev, struct bm_hb *bm)
+{
+	struct bm_lun *lun;
+	struct nvm_block *block;
+	sector_t lun_iter, blk_iter, cur_block_id = 0;
+	int ret;
+
+	bm_for_each_lun(bm, lun, lun_iter) {
+		lun->vlun.blocks = vzalloc(sizeof(struct nvm_block) *
+						lun->vlun.nr_blocks);
+		if (!lun->vlun.blocks)
+			return -ENOMEM;
+
+		for (blk_iter = 0; blk_iter < lun->vlun.nr_blocks; blk_iter++) {
+			block = &lun->vlun.blocks[blk_iter];
+
+			INIT_LIST_HEAD(&block->list);
+
+			block->lun = &lun->vlun;
+			block->id = cur_block_id++;
+
+			/* First block is reserved for device */
+			if (unlikely(lun_iter == 0 && blk_iter == 0))
+				continue;
+
+			list_add_tail(&block->list, &lun->free_list);
+		}
+
+		if (dev->ops->get_bb_tbl) {
+			ret = dev->ops->get_bb_tbl(dev->q, lun->vlun.id,
+			lun->vlun.nr_blocks, hb_block_bb, bm);
+			if (ret)
+				pr_err("bm_hb: could not read BB table\n");
+		}
+	}
+
+	if (dev->ops->get_l2p_tbl) {
+		ret = dev->ops->get_l2p_tbl(dev->q, 0, dev->total_pages,
+							hb_block_map, dev);
+		if (ret) {
+			pr_err("bm_hb: could not read L2P table.\n");
+			pr_warn("bm_hb: default block initialization");
+		}
+	}
+
+	return 0;
+}
+
+static int hb_register(struct nvm_dev *dev)
+{
+	struct bm_hb *bm;
+	int ret;
+
+	if (!(dev->features.rsp & NVM_RSP_L2P))
+		return 0;
+
+	bm = kzalloc(sizeof(struct bm_hb), GFP_KERNEL);
+	if (!bm)
+		return -ENOMEM;
+
+	bm->nr_luns = dev->nr_luns;
+	dev->bmp = bm;
+
+	ret = hb_luns_init(dev, bm);
+	if (ret) {
+		pr_err("bm_hb: could not initialize luns\n");
+		goto err;
+	}
+
+	ret = hb_blocks_init(dev, bm);
+	if (ret) {
+		pr_err("bm_hb: could not initialize blocks\n");
+		goto err;
+	}
+
+	return 1;
+err:
+	kfree(bm);
+	return ret;
+}
+
+static void hb_unregister(struct nvm_dev *dev)
+{
+	hb_blocks_free(dev);
+	hb_luns_free(dev);
+	kfree(dev->bmp);
+	dev->bmp = NULL;
+}
+
+static struct nvm_block *hb_get_blk(struct nvm_dev *dev, struct nvm_lun *vlun,
+							unsigned long flags)
+{
+	struct bm_lun *lun = container_of(vlun, struct bm_lun, vlun);
+	struct nvm_block *blk = NULL;
+	int is_gc = flags & NVM_IOTYPE_GC;
+
+	BUG_ON(!lun);
+
+	spin_lock(&vlun->lock);
+
+	if (list_empty(&lun->free_list)) {
+		pr_err_ratelimited("bm_hb: lun %u have no free pages available",
+								lun->vlun.id);
+		spin_unlock(&vlun->lock);
+		goto out;
+	}
+
+	while (!is_gc && lun->vlun.nr_free_blocks < lun->reserved_blocks) {
+		spin_unlock(&vlun->lock);
+		goto out;
+	}
+
+	blk = list_first_entry(&lun->free_list, struct nvm_block, list);
+	list_move_tail(&blk->list, &lun->used_list);
+
+	lun->vlun.nr_free_blocks--;
+
+	spin_unlock(&vlun->lock);
+out:
+	return blk;
+}
+
+static void hb_put_blk(struct nvm_dev *dev, struct nvm_block *blk)
+{
+	struct nvm_lun *vlun = blk->lun;
+	struct bm_lun *lun = container_of(vlun, struct bm_lun, vlun);
+
+	spin_lock(&vlun->lock);
+
+	list_move_tail(&blk->list, &lun->free_list);
+	lun->vlun.nr_free_blocks++;
+
+	spin_unlock(&vlun->lock);
+}
+
+static int hb_submit_io(struct nvm_dev *dev, struct nvm_rq *rqd)
+{
+	if (!dev->ops->submit_io)
+		return 0;
+
+	return dev->ops->submit_io(dev->q, rqd);
+}
+
+static void hb_end_io(struct nvm_rq *rqd, int error)
+{
+	struct nvm_tgt_instance *ins = rqd->ins;
+
+	ins->tt->end_io(rqd, error);
+}
+
+static int hb_erase_blk(struct nvm_dev *dev, struct nvm_block *blk)
+{
+	if (!dev->ops->erase_block)
+		return 0;
+
+	return dev->ops->erase_block(dev->q, blk->id);
+}
+
+static struct nvm_lun *hb_get_luns(struct nvm_dev *dev, int begin, int end)
+{
+	struct bm_hb *bm = dev->bmp;
+
+	return &bm->luns[begin].vlun;
+}
+
+static void hb_free_blocks_print(struct nvm_dev *dev)
+{
+	struct bm_hb *bm = dev->bmp;
+	struct bm_lun *lun;
+	unsigned int i;
+
+	bm_for_each_lun(bm, lun, i)
+		pr_info("%s: lun%8u\t%u\n",
+					dev->name, i, lun->vlun.nr_free_blocks);
+}
+
+static struct nvm_bm_type bm_hb = {
+	.name		= "hb",
+	.version	= {0, 1, 0},
+
+	.register_bm	= hb_register,
+	.unregister_bm	= hb_unregister,
+
+	.get_blk	= hb_get_blk,
+	.put_blk	= hb_put_blk,
+
+	.submit_io	= hb_submit_io,
+	.end_io		= hb_end_io,
+	.erase_blk	= hb_erase_blk,
+
+	.get_luns	= hb_get_luns,
+	.free_blocks_print = hb_free_blocks_print,
+};
+
+static int __init hb_module_init(void)
+{
+	return nvm_register_bm(&bm_hb);
+}
+
+static void hb_module_exit(void)
+{
+	nvm_unregister_bm(&bm_hb);
+}
+
+module_init(hb_module_init);
+module_exit(hb_module_exit);
+MODULE_LICENSE("GPL v2");
+MODULE_DESCRIPTION("Block manager for Hybrid Open-Channel SSDs");
diff --git a/drivers/lightnvm/bm_hb.h b/drivers/lightnvm/bm_hb.h
new file mode 100644
index 0000000..b856a70
--- /dev/null
+++ b/drivers/lightnvm/bm_hb.h
@@ -0,0 +1,46 @@
+/*
+ * Copyright: Matias Bjorling <mb@xxxxxxxxxxx>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License version
+ * 2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ */
+
+#ifndef BM_HB_H_
+#define BM_HB_H_
+
+#include <linux/module.h>
+#include <linux/vmalloc.h>
+
+#include <linux/lightnvm.h>
+
+struct bm_lun {
+	struct nvm_lun vlun;
+
+	int reserved_blocks;
+	/* lun block lists */
+	struct list_head used_list;	/* In-use blocks */
+	struct list_head free_list;	/* Not used blocks i.e. released
+					 * and ready for use */
+	struct list_head bb_list;	/* Bad blocks. Mutually exclusive with
+					   free_list and used_list */
+
+	struct nvm_id_chnl *chnl;
+};
+
+struct bm_hb {
+	int nr_luns;
+	struct bm_lun *luns;
+};
+
+#define bm_for_each_lun(bm, lun, i) \
+		for ((i) = 0, lun = &(bm)->luns[0]; \
+			(i) < (bm)->nr_luns; (i)++, lun = &(bm)->luns[(i)])
+
+#endif /* BM_HB_H_ */
-- 
2.1.4

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