[bch-nvm-pages v9 2/6] bcache: initialize the nvm pages allocator

[Qiaowei Ren <qiaowei.ren@intel.com>]

From: Jianpeng Ma <jianpeng.ma@intel.com>

This patch define the prototype data structures in memory and initializes
the nvm pages allocator.

The nvm address space which is managed by this allocatior can consist of
many nvm namespaces, and some namespaces can compose into one nvm set,
like cache set. For this initial implementation, only one set can be
supported.

The users of this nvm pages allocator need to call regiseter_namespace()
to register the nvdimm device (like /dev/pmemX) into this allocator as
the instance of struct nvm_namespace.

v9:
  -Fix Kconfig dependance error(Reported-by Randy)
  -Fix an uninitialized return value(Colin)

Reported-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Jianpeng Ma <jianpeng.ma@intel.com>
Co-developed-by: Qiaowei Ren <qiaowei.ren@intel.com>
Signed-off-by: Qiaowei Ren <qiaowei.ren@intel.com>
Signed-off-by: Coly Li <colyli@suse.de>
Signed-off-by: Colin Ian King <colin.king@canonical.com>
---
 drivers/md/bcache/Kconfig     |   8 +
 drivers/md/bcache/Makefile    |   2 +-
 drivers/md/bcache/nvm-pages.c | 285 ++++++++++++++++++++++++++++++++++
 drivers/md/bcache/nvm-pages.h |  74 +++++++++
 drivers/md/bcache/super.c     |   3 +
 5 files changed, 371 insertions(+), 1 deletion(-)
 create mode 100644 drivers/md/bcache/nvm-pages.c
 create mode 100644 drivers/md/bcache/nvm-pages.h

diff --git a/drivers/md/bcache/Kconfig b/drivers/md/bcache/Kconfig
index d1ca4d059c20..3057da4cf8ff 100644
--- a/drivers/md/bcache/Kconfig
+++ b/drivers/md/bcache/Kconfig
@@ -35,3 +35,11 @@ config BCACHE_ASYNC_REGISTRATION
 	device path into this file will returns immediately and the real
 	registration work is handled in kernel work queue in asynchronous
 	way.
+
+config BCACHE_NVM_PAGES
+	bool "NVDIMM support for bcache (EXPERIMENTAL)"
+	depends on BCACHE
+	depends on LIBNVDIMM
+	depends on DAX
+	help
+	nvm pages allocator for bcache.
diff --git a/drivers/md/bcache/Makefile b/drivers/md/bcache/Makefile
index 5b87e59676b8..948e5ed2ca66 100644
--- a/drivers/md/bcache/Makefile
+++ b/drivers/md/bcache/Makefile
@@ -4,4 +4,4 @@ obj-$(CONFIG_BCACHE)	+= bcache.o
 
 bcache-y		:= alloc.o bset.o btree.o closure.o debug.o extents.o\
 	io.o journal.o movinggc.o request.o stats.o super.o sysfs.o trace.o\
-	util.o writeback.o features.o
+	util.o writeback.o features.o nvm-pages.o
diff --git a/drivers/md/bcache/nvm-pages.c b/drivers/md/bcache/nvm-pages.c
new file mode 100644
index 000000000000..976ab9002c17
--- /dev/null
+++ b/drivers/md/bcache/nvm-pages.c
@@ -0,0 +1,285 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Nvdimm page-buddy allocator
+ *
+ * Copyright (c) 2021, Intel Corporation.
+ * Copyright (c) 2021, Qiaowei Ren <qiaowei.ren@intel.com>.
+ * Copyright (c) 2021, Jianpeng Ma <jianpeng.ma@intel.com>.
+ */
+
+#ifdef CONFIG_BCACHE_NVM_PAGES
+
+#include "bcache.h"
+#include "nvm-pages.h"
+
+#include <linux/slab.h>
+#include <linux/list.h>
+#include <linux/mutex.h>
+#include <linux/dax.h>
+#include <linux/pfn_t.h>
+#include <linux/libnvdimm.h>
+#include <linux/mm_types.h>
+#include <linux/err.h>
+#include <linux/pagemap.h>
+#include <linux/bitmap.h>
+#include <linux/blkdev.h>
+
+struct bch_nvm_set *only_set;
+
+static void release_nvm_namespaces(struct bch_nvm_set *nvm_set)
+{
+	int i;
+	struct bch_nvm_namespace *ns;
+
+	for (i = 0; i < nvm_set->total_namespaces_nr; i++) {
+		ns = nvm_set->nss[i];
+		if (ns) {
+			blkdev_put(ns->bdev, FMODE_READ|FMODE_WRITE|FMODE_EXEC);
+			kfree(ns);
+		}
+	}
+
+	kfree(nvm_set->nss);
+}
+
+static void release_nvm_set(struct bch_nvm_set *nvm_set)
+{
+	release_nvm_namespaces(nvm_set);
+	kfree(nvm_set);
+}
+
+static int init_owner_info(struct bch_nvm_namespace *ns)
+{
+	struct bch_owner_list_head *owner_list_head = ns->sb->owner_list_head;
+
+	mutex_lock(&only_set->lock);
+	only_set->owner_list_head = owner_list_head;
+	only_set->owner_list_size = owner_list_head->size;
+	only_set->owner_list_used = owner_list_head->used;
+	mutex_unlock(&only_set->lock);
+
+	return 0;
+}
+
+static bool attach_nvm_set(struct bch_nvm_namespace *ns)
+{
+	bool rc = true;
+
+	mutex_lock(&only_set->lock);
+	if (only_set->nss) {
+		if (memcmp(ns->sb->set_uuid, only_set->set_uuid, 16)) {
+			pr_info("namespace id doesn't match nvm set\n");
+			rc = false;
+			goto unlock;
+		}
+
+		if (only_set->nss[ns->sb->this_namespace_nr]) {
+			pr_info("already has the same position(%d) nvm\n",
+					ns->sb->this_namespace_nr);
+			rc = false;
+			goto unlock;
+		}
+	} else {
+		memcpy(only_set->set_uuid, ns->sb->set_uuid, 16);
+		only_set->total_namespaces_nr = ns->sb->total_namespaces_nr;
+		only_set->nss = kcalloc(only_set->total_namespaces_nr,
+				sizeof(struct bch_nvm_namespace *), GFP_KERNEL);
+		if (!only_set->nss) {
+			rc = false;
+			goto unlock;
+		}
+	}
+
+	only_set->nss[ns->sb->this_namespace_nr] = ns;
+
+unlock:
+	mutex_unlock(&only_set->lock);
+	return rc;
+}
+
+static int read_nvdimm_meta_super(struct block_device *bdev,
+			      struct bch_nvm_namespace *ns)
+{
+	struct page *page;
+	struct bch_nvm_pages_sb *sb;
+
+	page = read_cache_page_gfp(bdev->bd_inode->i_mapping,
+			BCH_NVM_PAGES_SB_OFFSET >> PAGE_SHIFT, GFP_KERNEL);
+
+	if (IS_ERR(page))
+		return -EIO;
+
+	sb = page_address(page) + offset_in_page(BCH_NVM_PAGES_SB_OFFSET);
+
+	/* temporary use for DAX API */
+	ns->page_size = sb->page_size;
+	ns->pages_total = sb->pages_total;
+
+	put_page(page);
+
+	return 0;
+}
+
+struct bch_nvm_namespace *bch_register_namespace(const char *dev_path)
+{
+	struct bch_nvm_namespace *ns;
+	int err;
+	pgoff_t pgoff;
+	char buf[BDEVNAME_SIZE];
+	struct block_device *bdev;
+	uint64_t expected_csum;
+	int id;
+	char *path = NULL;
+
+	path = kstrndup(dev_path, 512, GFP_KERNEL);
+	if (!path) {
+		pr_err("kstrndup failed\n");
+		return ERR_PTR(-ENOMEM);
+	}
+
+	bdev = blkdev_get_by_path(strim(path),
+				  FMODE_READ|FMODE_WRITE|FMODE_EXEC,
+				  only_set);
+	if (IS_ERR(bdev)) {
+		pr_info("get %s error: %ld\n", dev_path, PTR_ERR(bdev));
+		kfree(path);
+		return ERR_PTR(PTR_ERR(bdev));
+	}
+
+	err = -ENOMEM;
+	ns = kzalloc(sizeof(struct bch_nvm_namespace), GFP_KERNEL);
+	if (!ns)
+		goto bdput;
+
+	err = -EIO;
+	if (read_nvdimm_meta_super(bdev, ns)) {
+		pr_info("%s read nvdimm meta super block failed.\n",
+			bdevname(bdev, buf));
+		goto free_ns;
+	}
+
+	err = -EOPNOTSUPP;
+	if (!bdev_dax_supported(bdev, ns->page_size)) {
+		pr_info("%s don't support DAX\n", bdevname(bdev, buf));
+		goto free_ns;
+	}
+
+	err = -EINVAL;
+	if (bdev_dax_pgoff(bdev, 0, ns->page_size, &pgoff)) {
+		pr_info("invalid offset of %s\n", bdevname(bdev, buf));
+		goto free_ns;
+	}
+
+	err = -ENOMEM;
+	ns->dax_dev = fs_dax_get_by_bdev(bdev);
+	if (!ns->dax_dev) {
+		pr_info("can't by dax device by %s\n", bdevname(bdev, buf));
+		goto free_ns;
+	}
+
+	err = -EINVAL;
+	id = dax_read_lock();
+	if (dax_direct_access(ns->dax_dev, pgoff, ns->pages_total,
+			      &ns->kaddr, &ns->start_pfn) <= 0) {
+		pr_info("dax_direct_access error\n");
+		dax_read_unlock(id);
+		goto free_ns;
+	}
+	dax_read_unlock(id);
+
+	ns->sb = ns->kaddr + BCH_NVM_PAGES_SB_OFFSET;
+
+	if (memcmp(ns->sb->magic, bch_nvm_pages_magic, 16)) {
+		pr_info("invalid bch_nvm_pages_magic\n");
+		goto free_ns;
+	}
+
+	if (ns->sb->sb_offset != BCH_NVM_PAGES_SB_OFFSET) {
+		pr_info("invalid superblock offset\n");
+		goto free_ns;
+	}
+
+	if (ns->sb->total_namespaces_nr != 1) {
+		pr_info("only one nvm device\n");
+		goto free_ns;
+	}
+
+	expected_csum = csum_set(ns->sb);
+	if (expected_csum != ns->sb->csum) {
+		pr_info("csum is not match with expected one\n");
+		goto free_ns;
+	}
+
+	err = -EEXIST;
+	if (!attach_nvm_set(ns))
+		goto free_ns;
+
+	/* Firstly attach */
+	if ((unsigned long)ns->sb->owner_list_head == BCH_NVM_PAGES_OWNER_LIST_HEAD_OFFSET) {
+		struct bch_nvm_pages_owner_head *sys_owner_head;
+		struct bch_nvm_pgalloc_recs *sys_pgalloc_recs;
+
+		ns->sb->owner_list_head = ns->kaddr + BCH_NVM_PAGES_OWNER_LIST_HEAD_OFFSET;
+		sys_pgalloc_recs = ns->kaddr + BCH_NVM_PAGES_SYS_RECS_HEAD_OFFSET;
+
+		sys_owner_head = &(ns->sb->owner_list_head->heads[0]);
+		sys_owner_head->recs[0] = sys_pgalloc_recs;
+		ns->sb->csum = csum_set(ns->sb);
+
+		sys_pgalloc_recs->owner = sys_owner_head;
+	} else
+		BUG_ON(ns->sb->owner_list_head !=
+			(ns->kaddr + BCH_NVM_PAGES_OWNER_LIST_HEAD_OFFSET));
+
+	ns->page_size = ns->sb->page_size;
+	ns->pages_offset = ns->sb->pages_offset;
+	ns->pages_total = ns->sb->pages_total;
+	ns->free = 0;
+	ns->bdev = bdev;
+	ns->nvm_set = only_set;
+	mutex_init(&ns->lock);
+
+	if (ns->sb->this_namespace_nr == 0) {
+		pr_info("only first namespace contain owner info\n");
+		err = init_owner_info(ns);
+		if (err < 0) {
+			pr_info("init_owner_info met error %d\n", err);
+			only_set->nss[ns->sb->this_namespace_nr] = NULL;
+			goto free_ns;
+		}
+	}
+
+	kfree(path);
+	return ns;
+free_ns:
+	kfree(ns);
+bdput:
+	blkdev_put(bdev, FMODE_READ|FMODE_WRITE|FMODE_EXEC);
+	kfree(path);
+	return ERR_PTR(err);
+}
+EXPORT_SYMBOL_GPL(bch_register_namespace);
+
+int __init bch_nvm_init(void)
+{
+	only_set = kzalloc(sizeof(*only_set), GFP_KERNEL);
+	if (!only_set)
+		return -ENOMEM;
+
+	only_set->total_namespaces_nr = 0;
+	only_set->owner_list_head = NULL;
+	only_set->nss = NULL;
+
+	mutex_init(&only_set->lock);
+
+	pr_info("bcache nvm init\n");
+	return 0;
+}
+
+void bch_nvm_exit(void)
+{
+	release_nvm_set(only_set);
+	pr_info("bcache nvm exit\n");
+}
+
+#endif /* CONFIG_BCACHE_NVM_PAGES */
diff --git a/drivers/md/bcache/nvm-pages.h b/drivers/md/bcache/nvm-pages.h
new file mode 100644
index 000000000000..87a0d2c46788
--- /dev/null
+++ b/drivers/md/bcache/nvm-pages.h
@@ -0,0 +1,74 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#ifndef _BCACHE_NVM_PAGES_H
+#define _BCACHE_NVM_PAGES_H
+
+#ifdef CONFIG_BCACHE_NVM_PAGES
+#include <linux/bcache-nvm.h>
+#endif /* CONFIG_BCACHE_NVM_PAGES */
+
+/*
+ * Bcache NVDIMM in memory data structures
+ */
+
+/*
+ * The following three structures in memory records which page(s) allocated
+ * to which owner. After reboot from power failure, they will be initialized
+ * based on nvm pages superblock in NVDIMM device.
+ */
+struct bch_nvm_namespace {
+	struct bch_nvm_pages_sb *sb;
+	void *kaddr;
+
+	u8 uuid[16];
+	u64 free;
+	u32 page_size;
+	u64 pages_offset;
+	u64 pages_total;
+	pfn_t start_pfn;
+
+	struct dax_device *dax_dev;
+	struct block_device *bdev;
+	struct bch_nvm_set *nvm_set;
+
+	struct mutex lock;
+};
+
+/*
+ * A set of namespaces. Currently only one set can be supported.
+ */
+struct bch_nvm_set {
+	u8 set_uuid[16];
+	u32 total_namespaces_nr;
+
+	u32 owner_list_size;
+	u32 owner_list_used;
+	struct bch_owner_list_head *owner_list_head;
+
+	struct bch_nvm_namespace **nss;
+
+	struct mutex lock;
+};
+extern struct bch_nvm_set *only_set;
+
+#ifdef CONFIG_BCACHE_NVM_PAGES
+
+struct bch_nvm_namespace *bch_register_namespace(const char *dev_path);
+int bch_nvm_init(void);
+void bch_nvm_exit(void);
+
+#else
+
+static inline struct bch_nvm_namespace *bch_register_namespace(const char *dev_path)
+{
+	return NULL;
+}
+static inline int bch_nvm_init(void)
+{
+	return 0;
+}
+static inline void bch_nvm_exit(void) { }
+
+#endif /* CONFIG_BCACHE_NVM_PAGES */
+
+#endif /* _BCACHE_NVM_PAGES_H */
diff --git a/drivers/md/bcache/super.c b/drivers/md/bcache/super.c
index 03e1fe4de53d..0674a76d9454 100644
--- a/drivers/md/bcache/super.c
+++ b/drivers/md/bcache/super.c
@@ -14,6 +14,7 @@
 #include "request.h"
 #include "writeback.h"
 #include "features.h"
+#include "nvm-pages.h"
 
 #include <linux/blkdev.h>
 #include <linux/debugfs.h>
@@ -2816,6 +2817,7 @@ static void bcache_exit(void)
 {
 	bch_debug_exit();
 	bch_request_exit();
+	bch_nvm_exit();
 	if (bcache_kobj)
 		kobject_put(bcache_kobj);
 	if (bcache_wq)
@@ -2914,6 +2916,7 @@ static int __init bcache_init(void)
 
 	bch_debug_init();
 	closure_debug_init();
+	bch_nvm_init();
 
 	bcache_is_reboot = false;
 
-- 
2.25.1